{"gene":"PARP2","run_date":"2026-06-10T05:19:53","timeline":{"discoveries":[{"year":1999,"finding":"PARP-2 is a damaged DNA-binding protein that catalyzes poly(ADP-ribose) polymer formation in a DNA-dependent manner and undergoes automodification; it is localized in the nucleus and accounts for residual poly(ADP-ribose) synthesis in PARP-1-deficient cells.","method":"Recombinant protein purification, in vitro DNA-binding assay, in vitro PAR synthesis assay, nuclear localization by cell fractionation/immunofluorescence","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro reconstitution of enzymatic activity with purified recombinant protein, replicated across multiple assays in a single rigorous study","pmids":["10364231"],"is_preprint":false},{"year":2002,"finding":"PARP-2 homo- and heterodimerizes with PARP-1 (with interacting interfaces mapped and being sites of reciprocal ADP-ribosylation), and physically interacts with BER proteins XRCC1, DNA polymerase β, and DNA ligase III. XRCC1 negatively regulates PARP-2 activity while serving as a polymer acceptor. PARP-2-deficient cells show delayed DNA strand-break resealing after alkylating agent treatment, confirming a role in BER.","method":"Co-immunoprecipitation, in vitro pulldown, PARP activity assays, gene knockout mouse model (MNU treatment), comet assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, mapped interaction interfaces, loss-of-function mouse model with defined repair phenotype, multiple orthogonal methods","pmids":["11948190"],"is_preprint":false},{"year":2003,"finding":"PARP-2-deficient mice are sensitive to ionizing radiation; PARP-2-/- MEFs show post-replicative genomic instability, G2/M accumulation, chromosome mis-segregation with kinetochore defects after alkylating agent treatment. Combined PARP-1/PARP-2 double knockout is lethal at gastrulation, demonstrating overlapping essential functions. Female-specific lethality in PARP-1+/-PARP-2-/- mice is linked to X chromosome instability.","method":"Gene knockout mouse models, metaphase chromosome analysis, flow cytometry, irradiation survival assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic loss-of-function with specific cytogenetic and developmental phenotypes, replicated across multiple genotypes","pmids":["12727891"],"is_preprint":false},{"year":2004,"finding":"PARP-2 physically binds to the telomere-protective protein TRF2 via the N-terminal domain of PARP-2 and the myb domain of TRF2. PARP activity covalently heteromodifies TRF2's dimerization domain and non-covalently modifies its myb domain via PAR binding, negatively regulating TRF2 DNA-binding activity. PARP-2-/- cells display spontaneously increased chromosome/chromatid breaks and telomere ends lacking TTAGGG repeats.","method":"Co-immunoprecipitation, in vitro pulldown, colocalization studies, ADP-ribosylation assays, telomere FISH on PARP-2-/- cells","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP with domain mapping, functional modification assay, knockout cellular phenotype, multiple orthogonal methods","pmids":["14749375"],"is_preprint":false},{"year":2005,"finding":"PARP-2 accumulates in the nucleolus and partially colocalizes with nucleophosmin/B23. PARP-2 interacts with B23 through its N-terminal DNA-binding domain via a constitutive association that does not depend on PARP activity or ribosomal transcription. A nuclear localization signal and nucleolar localization signal were identified in the N-terminal domain. PARP-1 and PARP-2 are delocalized from the nucleolus upon RNA polymerase I inhibition.","method":"Immunofluorescence, co-immunoprecipitation, NLS/NoLS mutagenesis, RNA pol I inhibition experiments, PARP-1/2-deficient MEFs","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct localization with functional NLS/NoLS mutagenesis, Co-IP, and loss-of-function validation in knockout cells","pmids":["15615785"],"is_preprint":false},{"year":2006,"finding":"PARP-2 interacts with thyroid transcription factor-1 (TTF-1) via the E (catalytic) domain of PARP-2 and the C-terminal domain of TTF-1; both PARP-2 and PARP-1 enhance the activity of the surfactant protein-B (Sftpb) gene promoter in vitro. PARP-2 is selectively expressed in fetal mouse lung epithelial cells.","method":"Co-immunoprecipitation with mass spectrometry identification, GST pulldown domain mapping, luciferase reporter assay, immunohistochemistry","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with MS validation, domain mapping pulldown, functional reporter assay, single lab","pmids":["16461352"],"is_preprint":false},{"year":2008,"finding":"PARP-2 binds TIF1β with high affinity both directly and through HP1α; Parp-2 and its activity are required for relocation of TIF1β to heterochromatic foci during primitive endodermal differentiation. Both PARP-1 and PARP-2 selectively poly(ADP-ribosyl)ate HP1α. PARP-2 binds HP1β but not HP1γ, whereas PARP-1 binds weakly to TIF1β and HP1β only.","method":"Co-immunoprecipitation, pulldown assays, in vitro ADP-ribosylation, shRNA knockdown, immunofluorescence colocalization, differentiation assays","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, in vitro enzymatic assay, shRNA loss-of-function with differentiation phenotype, single lab","pmids":["18676401"],"is_preprint":false},{"year":2008,"finding":"Lysines 36 and 37 in the nuclear localization signal of PARP-2 are acetylated by histone acetyltransferases PCAF and GCN5L in vitro and in vivo. Acetylation at these residues reduces PARP-2 DNA-binding activity and enzymatic ADP-ribosylation activity, and reduces auto-mono-ADP-ribosylation.","method":"In vitro acetyltransferase assay, site-directed mutagenesis (K36A, K37A), DNA-binding assay, auto-ADP-ribosylation assay, in vivo co-immunoprecipitation","journal":"The international journal of biochemistry & cell biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — site-directed mutagenesis combined with in vitro enzymatic assays and in vivo validation, multiple orthogonal methods in one study","pmids":["18436469"],"is_preprint":false},{"year":2009,"finding":"During immunoglobulin class switch recombination, Parp2 actively suppresses IgH/c-myc translocations, functioning as a translocation suppressor. Parp1 facilitates alternative (microhomology-mediated) end-joining. Neither Parp1 nor Parp2 is required for CSR per se, but Parp enzymatic activity is induced in an AID-dependent manner during CSR.","method":"Parp1/Parp2 knockout mouse B cells, CSR assays, translocation frequency analysis by PCR/Southern blot, ADP-ribose detection","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic knockouts with specific chromosomal translocation phenotype, epistasis with AID","pmids":["19364882"],"is_preprint":false},{"year":2009,"finding":"Parp2 is required for spermiogenesis; Parp2 interacts with transition protein TP2 and chaperone HSPA2 (Parp2-TP2 interaction partially mediated by poly(ADP-ribosyl)ation). Only Parp1 poly(ADP-ribosyl)ates HSPA2. A Parp1/Parp2/TP2/HSPA2 spermatid-specific complex was identified. Parp2 deficiency causes loss of TP2-expressing spermatids, defective chromatin condensation, and abnormal manchette microtubule formation.","method":"In vitro protein-protein interaction assays, ADP-ribosylation assays, immunohistochemistry, electron microscopy on Parp2-/- mouse testes","journal":"Experimental cell research","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct protein interaction assays with enzymatic validation, loss-of-function mouse model with ultrastructural phenotype","pmids":["19607827"],"is_preprint":false},{"year":2010,"finding":"Crystal structures of the catalytic domain of human PARP2 in complex with inhibitors 3-aminobenzamide and ABT-888 were determined, revealing structural features of the NAD+ binding site and enabling comparison with PARP1 for selective inhibitor design.","method":"X-ray crystallography","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — high-resolution crystal structure, single study","pmids":["20092359"],"is_preprint":false},{"year":2011,"finding":"PARP-2 acts as a direct transcriptional repressor of the SIRT1 promoter. PARP-2 deficiency increases SIRT1 expression and activity in myotubes (not via changes in NAD+ levels), promotes energy expenditure, increases mitochondrial content, and protects against diet-induced obesity in mice; however, PARP-2-/- mice are glucose intolerant due to defective pancreatic β-cell function.","method":"PARP-2 knockout mouse model, siRNA knockdown in myotubes, SIRT1 promoter reporter assay, ChIP, metabolic phenotyping, NAD+ measurements","journal":"Cell metabolism","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct promoter binding by ChIP, reporter assay, knockout mouse with defined metabolic phenotype, multiple orthogonal methods","pmids":["21459329"],"is_preprint":false},{"year":2011,"finding":"PARP1 and PARP2 modulate topoisomerase II beta (TOP2B) activity during spermiogenesis: PARP1 and PARP2 activity strongly inhibits TOP2B in vitro, and this inhibition is counteracted by PAR glycohydrolase activity. Genetic and pharmacological PARP inhibition both increase TOP2B covalent DNA binding in vivo in spermatids.","method":"In vitro TOP2B activity assay with purified PARP1/PARP2, pharmacological PARP inhibition in mice, genetic PARP knockout mice, TOP2B-DNA complex assay in spermatids","journal":"Biology of reproduction","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of PARP-mediated TOP2B inhibition, corroborated by in vivo genetic and pharmacological experiments","pmids":["21228215"],"is_preprint":false},{"year":2012,"finding":"PARP inhibitors trap PARP1 and PARP2 at damaged DNA, forming cytotoxic PARP-DNA complexes. The trapping potency differs among inhibitors (niraparib > olaparib >> veliparib) and does not correlate with catalytic inhibitory potency. Homologous recombination, post-replication repair, Fanconi anemia pathway, polymerase β, and FEN1 are critical for repairing trapped PARP-DNA complexes.","method":"Cellular PARP trapping assay, clonogenic survival, 30 genetically defined DT40 cell lines with specific DNA repair gene deletions","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Strong — systematic genetic epistasis across 30 cell lines, quantitative trapping assays, multiple orthogonal approaches","pmids":["23118055"],"is_preprint":false},{"year":2013,"finding":"PARP-2 interacts with AP site-containing DNA via Schiff base formation through its N-terminal domain. PARP-2, like PARP-1, inhibits APE1 activity by binding to AP sites, but unlike PARP-1, this inhibitory effect is not regulated by PAR synthesis. PARP-2 DNA binding is not modulated by autoPARylation.","method":"EMSA, cross-linking assays, APE1 activity assay in presence of PARP-2","journal":"Biochimie","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple in vitro biochemical assays, single lab, no in vivo confirmation","pmids":["25724268"],"is_preprint":false},{"year":2013,"finding":"PARP-2 interacts with and inhibits both DNA polymerase β and FEN1 in vitro. Unlike PARP-1, poly(ADP-ribosyl)ation by PARP-2 does not restore DNA pol β or FEN1 activity. PARP-2 can also modulate the poly(ADP-ribosyl)ation activity of PARP-1, decreasing it. PARP-2 shows highest affinity for flap-containing DNA but is most efficiently activated by 5'-overhang DNA.","method":"EMSA for DNA binding (Kd measurements), in vitro BER enzyme activity assays (pol β, FEN1), PAR synthesis assays","journal":"Biochimie","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple in vitro biochemical assays with quantitative measurements, single lab","pmids":["23357680"],"is_preprint":false},{"year":2013,"finding":"PARP-2 is a direct transcriptional suppressor of the SREBP1 promoter in a manner dependent on its enzymatic activity. PARP-2 deletion increases hepatic SREBP1 expression, inducing downstream lipogenic genes and resulting in higher hepatic cholesterol content and decreased serum HDL levels in mice.","method":"PARP-2 knockout mice, siRNA knockdown in HepG2 cells, promoter reporter assay, gene expression analysis, lipid measurements","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — promoter reporter assay, knockout mouse metabolic phenotype, single lab","pmids":["24365238"],"is_preprint":false},{"year":2014,"finding":"PARP-2 (and PARP-3) are selectively activated by DNA breaks harboring a 5' phosphate group, suggesting activation by specific DNA repair intermediates competent for ligation. The WGR domain is the central regulatory domain of PARP-2, not the N-terminal region (NTR). PARP-1, PARP-2, and PARP-3 share an allosteric activation mechanism involving local destabilization of the catalytic domain upon DNA binding.","method":"Biochemical activation assays with defined DNA substrates, domain deletion/mutagenesis analysis, in vitro PAR synthesis assays","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Strong — systematic in vitro reconstitution with substrate specificity analysis and domain mutagenesis, multiple orthogonal methods","pmids":["24928857"],"is_preprint":false},{"year":2014,"finding":"ARTD2/PARP2 is activated by RNA in addition to DNA. RNA binding is mediated by the N-terminal SAP domain. In cells, this RNA-stimulated ARTD2 activation contributes to increased PAR formation under combined genotoxic + RNA-accumulating conditions, predominantly through ARTD2 rather than ARTD1.","method":"In vitro PAR synthesis assay with RNA substrates, domain deletion analysis (SAP domain), siRNA knockdown in cells, Actinomycin D co-treatment experiments","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro reconstitution plus cellular knockdown validation, single lab","pmids":["24510188"],"is_preprint":false},{"year":2014,"finding":"PARP-2 deletion in mice causes chronic anemia due to shortened erythrocyte lifespan and impaired erythroid progenitor differentiation. PARP-2 deficiency triggers replicative stress in erythroblasts (γ-H2AX accumulation in S-phase, CHK1/RPA phosphorylation, micronuclei), activating p53-dependent DNA damage response, G2/M arrest, and apoptosis. Loss of pro-apoptotic Puma restores hematocrit; loss of p21 causes perinatal death by exacerbating erythropoiesis defects.","method":"PARP-2 knockout mice, flow cytometry, γ-H2AX staining, CHK1/RPA phosphorylation assays, genetic epistasis with Puma and p21 knockout","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean loss-of-function with defined cellular phenotype, genetic epistasis with multiple downstream effectors","pmids":["25501596"],"is_preprint":false},{"year":2014,"finding":"miR-149 directly inhibits PARP-2 expression, increasing cellular NAD+ and SIRT1 activity, which promotes mitochondrial biogenesis via PGC-1α activation. PARP-2 knockdown in skeletal muscle myotubes recapitulates miR-149 overexpression effects on SIRT1/PGC-1α pathway.","method":"miR-149 overexpression in myotubes, PARP-2 knockdown, NAD+ measurement, SIRT1 activity assay, PGC-1α and mitochondrial marker analysis","journal":"Diabetes","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with pathway readouts, single lab, mechanistic chain validated with multiple markers","pmids":["24757201"],"is_preprint":false},{"year":2015,"finding":"All three domains of PARP-2 (NTR, WGR, CAT) collectively contribute to DNA damage interaction. The NTR is natively disordered and is required for activation on specific DNA damage types but is not essential for PARP-2 localization to DNA damage sites. The WGR and CAT domains together recruit PARP-2 to DNA breaks.","method":"Biophysical analyses (SAXS/SEC-MALS indicating NTR disorder), structural studies, DNA-binding assays, live-cell laser micro-irradiation localization with domain deletion mutants, in vitro PAR synthesis assays","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — structural characterization combined with biochemical and live-cell localization assays using domain deletion mutants, multiple orthogonal methods","pmids":["26704974"],"is_preprint":false},{"year":2015,"finding":"PARP2 preferentially and specifically recognizes single DNA nicks (low binding to undamaged DNA or DSBs), and activation by SSBs drives synthesis of highly branched PAR. PARP1 has broader affinity (nicks and DSBs). PARP2 in dimeric form is more effective at PAR synthesis than monomer, opposite to PARP1. PARP2 suppresses PAR synthesis by PARP1 after SSB formation.","method":"Single-molecule AFM imaging, fluorescence titration, PAR synthesis biochemical assay with defined DNA substrates","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Strong — single-molecule AFM with biochemical corroboration, multiple substrate types tested, two independent methodological approaches","pmids":["26673720"],"is_preprint":false},{"year":2016,"finding":"The WGR domain of PARP2 is the key domain for DNA break detection; crystal structures of the ARTD2 WGR domain bound to DSB-mimicking DNA reveal end-to-end DNA interaction mode, how PARP2 recognizes nicked DNA and the 5'-phosphate group, and how it mediates DNA end joining in vitro. Mutagenesis of the WGR-DNA interface confirms WGR is critical for DNA binding and catalytic activation.","method":"X-ray crystallography, site-directed mutagenesis, in vitro activity assays, DNA-binding assays, stoichiometry measurements","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with extensive mutagenesis and biochemical validation, multiple orthogonal methods","pmids":["30321391"],"is_preprint":false},{"year":2016,"finding":"PARP-2 contains transcriptional repression activity independent of its enzymatic activity, recruiting HDAC5, HDAC7, and histone methyltransferase G9a to promoters of cell cycle-related genes and generating repressive chromatin marks (histone deacetylation and methylation).","method":"PARP-2 catalytic mutant overexpression, co-immunoprecipitation of HDAC5/7 and G9a, ChIP at target gene promoters, reporter assays","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ChIP, catalytic mutant to separate enzymatic from non-enzymatic function, single lab","pmids":["23291187"],"is_preprint":false},{"year":2017,"finding":"PARP2 stabilizes replication forks that encounter BER intermediates through Fbh1-dependent regulation of Rad51. PARP2 is dispensable for tolerance to SSBs alone or for homologous recombination dysfunction, but is redundant with PARP1 in BER. Combined PARP1+PARP2 disruption causes defective BER, elevated replication-associated DNA damage, inability to stabilize Rad51 at damaged replication forks, and uncontrolled DNA resection.","method":"PARP1/PARP2 single and double knockouts, replication fork stability assays, Rad51 focus analysis, Fbh1 genetic epistasis, DNA resection assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic knockouts with epistasis analysis (Fbh1), multiple cellular phenotypic readouts, pathway placement","pmids":["29467415"],"is_preprint":false},{"year":2017,"finding":"PARP2 controls DSB repair pathway choice independently of its PAR synthesis activity by limiting accumulation of the resection barrier 53BP1 at DNA damage sites, thereby promoting CtIP-dependent DNA end-resection and channeling repair toward HR, SSA, and alternative end-joining rather than canonical NHEJ.","method":"PARP2 knockout and catalytic mutant cells, 53BP1 focus analysis, CtIP-dependent resection assay, HR/SSA/A-EJ/C-EJ reporter assays","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 / Strong — catalytic mutant distinguishes enzymatic from structural function, multiple repair pathway reporters, defined molecular mechanism","pmids":["29036662"],"is_preprint":false},{"year":2018,"finding":"PARP2 is preferentially activated by PAR itself (not just DNA breaks), and this PAR-dependent activation leads PARP2 to preferentially catalyze branched PAR chain synthesis. The N-terminus of PARP2 directly binds PAR to promote enzymatic activity toward branched chain synthesis. The PBZ domain of APLF specifically recognizes branched PAR chains to regulate chromatin remodeling in the DNA damage response.","method":"In vitro PAR synthesis assay with pre-formed PAR as activator, N-terminus deletion/mutation, PAR structure analysis, APLF-PBZ pulldown with branched PAR","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution showing PAR-dependent activation, domain mutagenesis, and PAR structure characterization with downstream reader identification","pmids":["30104678"],"is_preprint":false},{"year":2018,"finding":"PARP2 and PARP3 can PARylate and MARylate (respectively) 5'- and 3'-terminal phosphate residues at double- and single-strand break termini of DNA molecules in vitro, demonstrating that PARPs can directly ADP-ribosylate DNA ends in addition to protein substrates.","method":"In vitro ADP-ribosylation assay with defined DNA substrates, PAR/MAR detection methods, cell-free extracts, anti-PAR antibody on purified genomic DNA from bleomycin-treated cells","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple in vitro reconstitution approaches with defined substrates, corroborated by cell-based detection","pmids":["29361132"],"is_preprint":false},{"year":2019,"finding":"PARP-2, but not PARP-1, is a critical component of the androgen receptor (AR) transcriptional machinery in prostate cancer cells through direct interaction with the pioneer factor FOXA1, facilitating AR recruitment to genome-wide prostate-specific enhancer regions. Selective PARP-2 targeting blocks PARP-2-FOXA1 interaction, attenuating AR-mediated gene expression and inhibiting PCa growth.","method":"Co-immunoprecipitation of PARP-2 with FOXA1, ChIP-seq for AR and PARP-2, siRNA/pharmacological PARP-2 knockdown, gene expression analysis, cell proliferation assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP with genome-wide ChIP-seq, loss-of-function with specific transcriptional and proliferation phenotypes, multiple orthogonal methods","pmids":["31266892"],"is_preprint":false},{"year":2020,"finding":"Cryo-EM structure of human PARP2-HPF1 bound to a nucleosome shows PARP2-HPF1 bridges two nucleosomes with broken DNA aligned for ligation. DNA break bridging induces conformational changes in PARP2 that signal DNA break recognition to the catalytic domain, licensing HPF1 binding and PARP2 activation. HPF1 switches PARP2 amino acid specificity from aspartate/glutamate to serine. Active PARP2 cycles through conformational states to exchange NAD+ and substrate.","method":"Cryo-electron microscopy structural determination of PARP2-HPF1-nucleosome complex","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — high-resolution cryo-EM structure with mechanistic interpretation of conformational activation, replicated by second cryo-EM study (PMID 33141820)","pmids":["32939087","33141820"],"is_preprint":false},{"year":2020,"finding":"The chromatin remodeler ALC1 (CHD1L) is strictly required for PARP2 release from DNA damage sites. Catalytic inactivation of ALC1 quantitatively traps PARP2 but not PARP1. PARP inhibitors robustly trap PARP2 at DNA lesions, impacting cellular DNA damage responses.","method":"Live-cell imaging of PARP2 foci, ALC1 catalytic mutant cell lines, PARP inhibitor treatment, PARP2 vs PARP1 differential analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — live-cell imaging with genetic manipulation, specific dissociation of PARP1 and PARP2 trapping, defined mechanistic role for ALC1","pmids":["33275888"],"is_preprint":false},{"year":2020,"finding":"PARP2 deficiency in myeloid cells increases immature myeloid cell populations in bone marrow and impairs CCL3 chemokine expression by enhancing transcriptional repression by β-catenin, creating an immune-suppressive microenvironment that promotes breast cancer bone metastasis.","method":"Myeloid-specific PARP2 knockout mice, osteoclast differentiation assays, bone marrow cell population analysis, β-catenin ChIP, CCL3 expression analysis, T cell population analysis","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional knockout with ChIP mechanistic link, single lab, complex phenotype","pmids":["32221289"],"is_preprint":false},{"year":2021,"finding":"Crystal structure of PARP2 in complex with activating 5'-phosphorylated DNA shows the WGR domain bridges the dsDNA gap and joins DNA ends; DNA binding causes major conformational changes including reorganization of helical fragments in the regulatory domain, relieving autoinhibition. The activated conformation allows NAD+ binding and HPF1 association (which switches residue specificity from glutamate to serine).","method":"X-ray crystallography, comparison with PARP1 crystal structures, in vitro activity assays with HPF1","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with mechanistic validation of conformational changes and HPF1 interaction, corroborates cryo-EM findings","pmids":["34108479"],"is_preprint":false},{"year":2021,"finding":"HPF1 has a dual function with PARP2: it can both stimulate DNA-dependent and DNA-independent autoPARylation of PARP2 (and histone heteroPARylation) at defined HPF1/NAD+ concentrations, and suppress PARylation activity (promoting NAD+ hydrolysis) at higher concentrations. PARP2 is more efficiently stimulated by HPF1 in automodification and is more active in histone heteroPARylation than automodification.","method":"In vitro PARylation assays with purified PARP2, HPF1, and nucleosomes; NAD+ hydrolase assay; comparison with PARP1","journal":"Communications biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — reconstituted in vitro system with purified components, systematic concentration-dependence analysis, single lab","pmids":["34732825"],"is_preprint":false},{"year":2021,"finding":"PARP-1 and PARP-2 deficiency in the uterus leads to pregnancy loss due to decidualization failure. Absence of PARP-1 and PARP-2 increases p53 signaling and senescent decidual cells. Embryo attachment and luminal epithelium removal are unaffected; the defect is specifically at decidualization.","method":"Uterine-specific PARP-1/PARP-2 conditional knockout mice, histology, p53 signaling analysis, senescence markers, embryo attachment assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional knockout with specific phenotypic placement of defect, single lab","pmids":["34580230"],"is_preprint":false},{"year":2021,"finding":"PARP2 predominantly functions in single-strand break repair at actively transcribed DNA regions; this function is bypassed when transcription is inhibited. CSB chromatin remodeler recruits XRCC1 and HPF1 downstream of PARP1 and PARP2, and CSB regulates SSBR mediated by both PARP1 and PARP2.","method":"Chromatin co-fractionation, alkaline comet assay for SSBR kinetics, transcription inhibition experiments, PARP1/PARP2-deficient cells","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — fractionation studies with functional repair assay, single lab, transcription-dependence validated","pmids":["37326017"],"is_preprint":false},{"year":2022,"finding":"PARP inhibitors trap PARP2 by switching its recruitment mode from predominantly PARP1- and PAR-dependent rapid exchange to WGR domain-mediated stalling on DNA. In PARP1-deficient cells, residual PARP2 foci are DNA-dependent and require the WGR domain (R140 critical) and catalytic domain (H415). PARP2 trapping by inhibitors is independent of auto-PARylation.","method":"Live-cell imaging in PARP1-deficient cells, WGR (R140A) and catalytic (H415A) domain PARP2 mutants, PARP inhibitor treatment (niraparib, talazoparib, olaparib)","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 / Strong — live-cell imaging with domain-specific mutants and genetic deletion, multiple inhibitors tested, mechanistic dissection of trapping mode","pmids":["35349716"],"is_preprint":false},{"year":2023,"finding":"Certain clinical PARP inhibitors exert an allosteric effect on PARP2 that increases its retention on DNA breaks through communication between the catalytic and DNA-binding regions; this is distinct from PARP1 where no clinical PARPi exhibits allosteric retention. AZD5305 exhibits a clear reverse allosteric effect on PARP2.","method":"Biochemical PARP2 DNA retention assay, PARP2 allosteric mutant mimicking inhibitor-bound state, live-cell imaging of PARP2 at damage sites","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 2 / Strong — biochemical allosteric assay with confirmatory live-cell imaging and allosteric mutant, clearly distinguishes PARP1 from PARP2 mechanisms","pmids":["36961901"],"is_preprint":false},{"year":2023,"finding":"PARP2 forms a remarkably stable mechanical bridge (rupture force ~85 pN) across blunt-end 5'-phosphorylated DSBs and restores torsional continuity. PARP2 switches between bridging and end-binding modes depending on DNA overhang type. In contrast, PARP1 does not form bridging interactions across blunt or short overhang DSBs and competes away PARP2 bridge formation.","method":"Single-molecule magnetic tweezers force spectroscopy, defined DSB substrates with various overhangs","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — single-molecule biophysical reconstitution with quantitative force measurements and multiple substrate types","pmids":["37216533"],"is_preprint":false},{"year":2024,"finding":"DNA replication specifically activates PARP2 robustly; PARP2 is selectively recruited and activated by 5'-phosphorylated nicks (5'p-nicks) between Okazaki fragments. Catalytically inactive PARP2 (E534A), but not absent PARP2, impedes Ligase 1- and Ligase 3-mediated ligation, causing dose-dependent replication fork collapse. This PARylation-dependent structural function at nicks is essential for erythropoiesis and explains PARPi-induced anemia.","method":"Parp2 E534A knock-in mice, comparison with Parp2-/- and Lig1-/- mice, Okazaki fragment ligation assay, replication fork analysis, Tp53/Chk2 genetic epistasis, selective PARP2 recruitment to 5'p-nicks","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — catalytic knock-in vs knockout genetic dissection, in vitro ligation assay, multiple epistasis backgrounds, mechanistic separation of enzymatic and structural functions","pmids":["39383878"],"is_preprint":false},{"year":2024,"finding":"PARP2 promotes replication stress-induced telomere fragility via the break-induced replication (BIR) pathway by orchestrating DNA end resection, strand invasion, and BIR-dependent mitotic DNA synthesis through POLD3 recruitment and activity.","method":"PARP2 knockout cells, BIR reporter assay, POLD3 recruitment analysis, telomere fragility assay (FISH), BLM helicase depletion model, oxidative lesion induction","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with mechanistic pathway readouts, single lab, multiple assays","pmids":["38565848"],"is_preprint":false}],"current_model":"PARP2 is a DNA damage-activated ADP-ribosyltransferase that is selectively recruited and activated by 5'-phosphorylated DNA nicks and breaks via its WGR domain (which bridges DNA ends and undergoes allosteric conformational changes to relieve autoinhibition), catalyzes both linear and branched poly(ADP-ribose) synthesis on protein substrates (switching to serine specificity with HPF1) and directly on DNA termini, operates redundantly with PARP1 in base excision repair and SSB repair (while having specialized roles in replication fork stabilization via Rad51/Fbh1, DSB repair pathway choice via 53BP1 suppression, branched PAR synthesis, and POLD3-dependent break-induced replication at telomeres), and also acts as a transcriptional repressor of SIRT1 and SREBP1 promoters and interacts with multiple partners including TRF2, FOXA1/AR, TIF1β/HP1α, and BER scaffold proteins XRCC1/pol β/LigIII, with its activity regulated by acetylation at K36/K37 and by PARP inhibitors that allosterically trap it on DNA through WGR-mediated stalling."},"narrative":{"mechanistic_narrative":"PARP2 is a nuclear DNA damage-activated ADP-ribosyltransferase that catalyzes poly(ADP-ribose) synthesis in a DNA-dependent manner and undergoes automodification, accounting for the residual PAR synthesis in PARP1-deficient cells [PMID:10364231]. It is selectively recruited and activated by DNA breaks bearing a 5'-phosphate, particularly single-strand nicks, with the WGR domain serving as the central regulatory module that bridges DNA ends and undergoes conformational changes relieving catalytic-domain autoinhibition [PMID:24928857, PMID:26673720, PMID:30321391, PMID:34108479]; the cofactor HPF1 binds the activated enzyme and switches its amino-acid specificity from aspartate/glutamate to serine [PMID:32939087, PMID:33141820, PMID:34108479]. Beyond protein modification, PARP2 is itself activated by PAR to preferentially build branched PAR chains read by APLF, and can directly ADP-ribosylate 5'- and 3'-terminal phosphates at DNA break termini [PMID:30104678, PMID:29361132]. Functionally PARP2 operates redundantly with PARP1 in base excision and single-strand break repair—interacting with the BER scaffold XRCC1, DNA polymerase β and DNA ligase III [PMID:11948190, PMID:29467415, PMID:37326017]—while carrying specialized structural roles: it stabilizes replication forks via Fbh1-dependent Rad51 regulation [PMID:29467415], controls DSB repair pathway choice independently of its catalytic activity by limiting 53BP1 to promote CtIP-dependent resection [PMID:29036662], bridges DNA ends as a stable mechanical clamp [PMID:37216533], and seals 5'-phosphorylated nicks between Okazaki fragments in a PARylation-dependent structural function essential for erythropoiesis [PMID:39383878]. Genetic loss causes radiosensitivity, genomic and telomeric instability, and combined PARP1/PARP2 deletion is embryonic lethal, establishing overlapping essential functions [PMID:12727891, PMID:14749375]. PARP2 also acts as a transcriptional repressor of the SIRT1 and SREBP1 promoters, linking it to mitochondrial biogenesis, energy expenditure and lipid metabolism [PMID:21459329, PMID:24365238], and is a component of the FOXA1/androgen-receptor transcriptional machinery in prostate cancer [PMID:31266892]. Clinical PARP inhibitors trap PARP2 on DNA by switching its recruitment to WGR-mediated stalling and, for certain inhibitors, through a reverse allosteric effect distinct from PARP1, with the chromatin remodeler ALC1 required for PARP2 release from damage sites [PMID:33275888, PMID:35349716, PMID:36961901].","teleology":[{"year":1999,"claim":"Established that a second DNA-dependent PARP exists, explaining residual PAR synthesis in PARP1-null cells and defining PARP2 as a nuclear damaged-DNA-binding ADP-ribosyltransferase.","evidence":"Recombinant protein purification, in vitro DNA-binding and PAR synthesis assays, nuclear localization by fractionation/immunofluorescence","pmids":["10364231"],"confidence":"High","gaps":["DNA substrate specificity not defined","no domain dissection of activation mechanism"]},{"year":2002,"claim":"Placed PARP2 physically and functionally in the base excision repair machinery and showed it dimerizes with PARP1, defining its repair partners and a loss-of-function repair phenotype.","evidence":"Reciprocal Co-IP and pulldown with XRCC1/pol β/LigIII, interaction interface mapping, PARP2-knockout mouse comet assay after MNU","pmids":["11948190"],"confidence":"High","gaps":["redundancy with PARP1 not quantitatively separated","no structural basis for substrate handoff"]},{"year":2003,"claim":"Demonstrated PARP2 is required for genome stability and shares essential developmental functions with PARP1, since double knockout is lethal at gastrulation.","evidence":"Knockout mouse genetics, metaphase cytogenetics, irradiation survival, flow cytometry","pmids":["12727891"],"confidence":"High","gaps":["molecular basis of kinetochore/segregation defect unresolved","individual vs redundant contributions not separated"]},{"year":2004,"claim":"Connected PARP2 to telomere protection through direct modification of TRF2, explaining telomeric instability in PARP2-null cells.","evidence":"Reciprocal Co-IP with domain mapping, ADP-ribosylation assays, telomere FISH in knockout cells","pmids":["14749375"],"confidence":"High","gaps":["in vivo significance of TRF2 modification not established","no structural detail of the interaction"]},{"year":2005,"claim":"Localized PARP2 to the nucleolus via an N-terminal NLS/NoLS and constitutive B23 association, broadening its subnuclear distribution beyond damage sites.","evidence":"Immunofluorescence, Co-IP, NLS/NoLS mutagenesis, RNA pol I inhibition in PARP1/2-deficient MEFs","pmids":["15615785"],"confidence":"High","gaps":["functional consequence of nucleolar localization unclear","no link to a nucleolar substrate"]},{"year":2008,"claim":"Identified post-translational and heterochromatin-linked regulation of PARP2, showing acetylation at K36/K37 dampens its activity and that it modifies HP1α and partners with TIF1β during differentiation.","evidence":"In vitro acetyltransferase assays, K36A/K37A mutagenesis, DNA-binding/auto-ADP-ribosylation assays; Co-IP, in vitro modification and shRNA differentiation assays","pmids":["18436469","18676401"],"confidence":"High","gaps":["in vivo stoichiometry of acetylation unknown","deacetylase that reverses K36/K37 not identified"]},{"year":2009,"claim":"Defined non-repair physiological roles of PARP2 in immunoglobulin class-switch translocation suppression and in spermiogenesis chromatin condensation.","evidence":"Parp1/Parp2 knockout B cells with translocation assays; protein-interaction and ADP-ribosylation assays with TP2/HSPA2, EM on Parp2-/- testes","pmids":["19364882","19607827"],"confidence":"High","gaps":["mechanism of translocation suppression not molecular","whether spermatid complex is direct or scaffolded unclear"]},{"year":2010,"claim":"Provided the first crystallographic view of the PARP2 catalytic domain with inhibitors, enabling structure-guided selective inhibitor design.","evidence":"X-ray crystallography of catalytic domain with 3-AB and ABT-888","pmids":["20092359"],"confidence":"High","gaps":["no DNA-bound or full-length structure","allosteric activation not captured"]},{"year":2011,"claim":"Revealed PARP2 as a transcriptional repressor of SIRT1, linking it to mitochondrial biogenesis, energy metabolism and β-cell function independent of NAD+ levels.","evidence":"Knockout mice, myotube siRNA, SIRT1 promoter ChIP and reporter assays, metabolic phenotyping","pmids":["21459329"],"confidence":"High","gaps":["whether repression requires catalytic activity not resolved here","co-repressor partners undefined"]},{"year":2013,"claim":"Extended PARP2's transcriptional and non-enzymatic regulatory repertoire to SREBP1 lipogenic control and to enzyme-independent chromatin repression via HDAC5/7 and G9a recruitment.","evidence":"Knockout mice and HepG2 siRNA with SREBP1 reporter/lipid analysis; catalytic-mutant overexpression, Co-IP and ChIP at cell-cycle gene promoters","pmids":["24365238","23291187"],"confidence":"Medium","gaps":["single-lab findings","direct vs indirect promoter occupancy not fully distinguished"]},{"year":2013,"claim":"Characterized PARP2's biochemical interactions with BER intermediates, showing it binds AP sites and inhibits APE1, pol β and FEN1 differently from PARP1, with distinct DNA-substrate preferences.","evidence":"EMSA, Schiff-base cross-linking, in vitro APE1/pol β/FEN1 activity and PAR synthesis assays","pmids":["25724268","23357680"],"confidence":"Medium","gaps":["no in vivo validation","physiological relevance of enzyme inhibition unclear"]},{"year":2012,"claim":"Established PARP inhibitor trapping of PARP1 and PARP2 on DNA as a cytotoxic mechanism distinct from catalytic inhibition, and mapped repair pathways that resolve trapped complexes.","evidence":"Cellular trapping and clonogenic assays across 30 genetically defined DT40 lines; in vitro TOP2B inhibition with purified PARPs plus genetic/pharmacological mouse spermatid assays","pmids":["23118055","21228215"],"confidence":"High","gaps":["PARP2-specific trapping mechanism not yet dissected","structural basis of trapping unresolved"]},{"year":2014,"claim":"Defined the activation logic and domain architecture of PARP2: activation by 5'-phosphorylated breaks, the WGR domain as central regulator, a shared allosteric destabilization mechanism, and RNA as an additional activator via the SAP domain.","evidence":"Biochemical activation assays with defined DNA/RNA substrates, domain deletion/mutagenesis, cellular knockdown with RNA-accumulating conditions","pmids":["24928857","24510188"],"confidence":"High","gaps":["structural detail of the WGR-DNA contact not yet solved","physiological role of RNA activation unclear"]},{"year":2014,"claim":"Tied PARP2 loss to replicative stress in erythropoiesis and to a miR-149/NAD+/SIRT1 metabolic axis, revealing tissue-level consequences of PARP2 deficiency.","evidence":"Knockout mice with γ-H2AX/CHK1/RPA assays and Puma/p21 epistasis; miR-149 overexpression and PARP2 knockdown in myotubes with NAD+/SIRT1/PGC-1α readouts","pmids":["25501596","24757201"],"confidence":"High","gaps":["molecular source of erythroblast replication stress not pinpointed here","miR-149 axis is single-lab"]},{"year":2015,"claim":"Resolved PARP2 substrate recognition at single-molecule and domain resolution, showing preferential recognition of single nicks, branched PAR output from SSBs, and collective contribution of NTR/WGR/CAT domains to damage engagement.","evidence":"SAXS/SEC-MALS, single-molecule AFM, fluorescence titration, live-cell laser micro-irradiation with domain-deletion mutants, PAR synthesis assays","pmids":["26704974","26673720"],"confidence":"High","gaps":["atomic-resolution DNA-bound structure still lacking","functional role of branched PAR not yet defined"]},{"year":2016,"claim":"Provided crystallographic and structural definition of WGR-mediated DNA end recognition, showing PARP2 reads the 5'-phosphate and bridges DNA ends to drive catalytic activation.","evidence":"X-ray crystallography of WGR-DNA complex with WGR-interface mutagenesis and in vitro activity/binding assays","pmids":["30321391"],"confidence":"High","gaps":["full-length conformational change not captured","HPF1 not included"]},{"year":2017,"claim":"Separated PARP2's catalytic from structural functions at the replication fork and at DSBs, defining Fbh1/Rad51-dependent fork stabilization and a non-enzymatic 53BP1-limiting role in repair pathway choice.","evidence":"PARP1/PARP2 single and double knockouts with fork stability, Rad51 focus, Fbh1 epistasis and resection assays; catalytic-mutant cells with 53BP1 foci and HR/SSA/A-EJ/C-EJ reporters","pmids":["29467415","29036662"],"confidence":"High","gaps":["how PARP2 mechanistically limits 53BP1 not defined","direct vs indirect Fbh1 regulation unclear"]},{"year":2018,"claim":"Discovered PAR-induced activation of PARP2 driving branched-chain synthesis read by APLF, and direct ADP-ribosylation of DNA termini, expanding PARP2's catalytic outputs beyond protein modification.","evidence":"In vitro PAR synthesis with pre-formed PAR activator, N-terminus mutagenesis, PAR structure analysis, APLF-PBZ pulldown; in vitro DNA-end ADP-ribosylation with cell-based detection","pmids":["30104678","29361132"],"confidence":"High","gaps":["cellular abundance and turnover of DNA-ADP-ribosylation unknown","branched PAR signaling outputs incompletely mapped"]},{"year":2019,"claim":"Identified a PARP2-specific transcriptional role in prostate cancer, where it bridges FOXA1 to direct genome-wide androgen-receptor recruitment, distinguishing it functionally from PARP1.","evidence":"Co-IP with FOXA1, AR/PARP2 ChIP-seq, siRNA/pharmacological knockdown, expression and proliferation assays","pmids":["31266892"],"confidence":"High","gaps":["whether catalytic activity is required not resolved","structural basis of FOXA1 interaction unknown"]},{"year":2020,"claim":"Provided high-resolution structural mechanism of PARP2 activation on chromatin: DNA-break bridging drives conformational signaling that licenses HPF1 binding and switches modification specificity to serine.","evidence":"Cryo-EM of PARP2-HPF1-nucleosome complex (two independent structures); ALC1 catalytic-mutant live-cell imaging for PARP2 release","pmids":["32939087","33141820","33275888"],"confidence":"High","gaps":["dynamics of NAD+/substrate cycling inferred not directly observed","in vivo HPF1 occupancy not quantified"]},{"year":2020,"claim":"Extended PARP2 function to the tumor immune microenvironment, where myeloid PARP2 loss enhances β-catenin repression of CCL3 to promote breast cancer bone metastasis.","evidence":"Myeloid-specific knockout mice, bone marrow population analysis, β-catenin ChIP and CCL3 expression","pmids":["32221289"],"confidence":"Medium","gaps":["single-lab finding","direct PARP2-β-catenin mechanism not biochemically defined"]},{"year":2021,"claim":"Captured the DNA-induced activated conformation crystallographically and dissected HPF1's biphasic, concentration-dependent control over PARP2 PARylation versus NAD+ hydrolysis.","evidence":"X-ray crystallography of PARP2-5'p-DNA with PARP1 comparison; reconstituted in vitro PARylation and NAD+ hydrolase assays with PARP2/HPF1/nucleosomes","pmids":["34108479","34732825"],"confidence":"High","gaps":["cellular HPF1 concentrations relative to thresholds unknown","physiological balance of activities undefined"]},{"year":2021,"claim":"Established that PARP2's single-strand break repair function is concentrated at actively transcribed loci and connected SSBR to the CSB chromatin remodeler and decidualization-linked pregnancy maintenance.","evidence":"Chromatin co-fractionation and comet assays with transcription inhibition; uterine-specific PARP1/PARP2 conditional knockout with p53/senescence analysis","pmids":["37326017","34580230"],"confidence":"Medium","gaps":["single-lab findings","mechanistic basis of transcription coupling not fully defined"]},{"year":2023,"claim":"Resolved the biophysical and pharmacological basis of PARP2 trapping, showing WGR-mediated stalling and inhibitor-driven mechanical bridging of DSBs, and a PARP2-specific reverse allosteric retention effect absent in PARP1.","evidence":"Live-cell imaging in PARP1-deficient cells with WGR (R140A)/catalytic (H415A) mutants; biochemical retention assays and allosteric mutants; single-molecule magnetic tweezers force spectroscopy","pmids":["35349716","36961901","37216533"],"confidence":"High","gaps":["clinical relevance of allosteric retention to therapy response not established","in vivo prevalence of bridging mode unknown"]},{"year":2024,"claim":"Defined PARP2's essential PARylation-dependent structural role in sealing Okazaki-fragment 5'p-nicks during replication and in driving POLD3-dependent break-induced replication at telomeres, mechanistically explaining PARPi-induced anemia.","evidence":"Parp2 E534A catalytic knock-in vs knockout mice, in vitro ligation assays, replication fork and Tp53/Chk2 epistasis; PARP2 knockout cells with BIR reporter, POLD3 recruitment and telomere fragility assays","pmids":["39383878","38565848"],"confidence":"High","gaps":["BIR pathway finding is single-lab","how catalytically inactive PARP2 impedes ligation structurally not fully resolved"]},{"year":null,"claim":"How PARP2's diverse functions—transcriptional repression, branched PAR signaling, replication-nick sealing, and DSB bridging—are coordinated and selected within a cell, and which are most therapeutically exploitable, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["no unified model linking transcriptional and repair roles","in vivo determinants of catalytic vs structural function selection unknown","PARP2-selective inhibitor consequences across tissues incompletely mapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[0,17,27,28]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,28,30,34]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0,14,17,22,23]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[18]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[11,16,24,29]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[3,6,30]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,4]},{"term_id":"GO:0005730","term_label":"nucleolus","supporting_discovery_ids":[4]},{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[3,30]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[1,25,26,36]},{"term_id":"R-HSA-69306","term_label":"DNA Replication","supporting_discovery_ids":[25,40,41]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[11,16,24,29]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[6,24,27]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[11,16,20]}],"complexes":["PARP2-HPF1-nucleosome complex","PARP1/PARP2/TP2/HSPA2 spermatid complex"],"partners":["PARP1","XRCC1","HPF1","TRF2","FOXA1","HP1ALPHA","TIF1BETA","FEN1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UGN5","full_name":"Poly [ADP-ribose] polymerase 2","aliases":["ADP-ribosyltransferase diphtheria toxin-like 2","ARTD2","DNA ADP-ribosyltransferase PARP2","NAD(+) ADP-ribosyltransferase 2","ADPRT-2","Poly[ADP-ribose] synthase 2","pADPRT-2","Protein poly-ADP-ribosyltransferase PARP2"],"length_aa":583,"mass_kda":66.2,"function":"Poly-ADP-ribosyltransferase that mediates poly-ADP-ribosylation of proteins and plays a key role in DNA repair (PubMed:10364231, PubMed:25043379, PubMed:27471034, PubMed:30104678, PubMed:32028527, PubMed:32939087, PubMed:34108479, PubMed:34486521, PubMed:34874266). Mediates glutamate, aspartate or serine ADP-ribosylation of proteins: the ADP-D-ribosyl group of NAD(+) is transferred to the acceptor carboxyl group of target residues and further ADP-ribosyl groups are transferred to the 2'-position of the terminal adenosine moiety, building up a polymer with an average chain length of 20-30 units (PubMed:25043379, PubMed:30104678, PubMed:30321391). Serine ADP-ribosylation of proteins constitutes the primary form of ADP-ribosylation of proteins in response to DNA damage (PubMed:32939087). Mediates glutamate and aspartate ADP-ribosylation of target proteins in absence of HPF1 (PubMed:25043379). Following interaction with HPF1, catalyzes serine ADP-ribosylation of target proteins; HPF1 conferring serine specificity by completing the PARP2 active site (PubMed:28190768, PubMed:32028527, PubMed:34108479, PubMed:34486521, PubMed:34874266). PARP2 initiates the repair of double-strand DNA breaks: recognizes and binds DNA breaks within chromatin and recruits HPF1, licensing serine ADP-ribosylation of target proteins, such as histones, thereby promoting decompaction of chromatin and the recruitment of repair factors leading to the reparation of DNA strand breaks (PubMed:10364231, PubMed:32939087, PubMed:34108479). HPF1 initiates serine ADP-ribosylation but restricts the polymerase activity of PARP2 in order to limit the length of poly-ADP-ribose chains (PubMed:34732825, PubMed:34795260). Specifically mediates formation of branched poly-ADP-ribosylation (PubMed:30104678). Branched poly-ADP-ribose chains are specifically recognized by some factors, such as APLF (PubMed:30104678). In addition to proteins, also able to ADP-ribosylate DNA: preferentially acts on 5'-terminal phosphates at DNA strand breaks termini in nicked duplex (PubMed:27471034, PubMed:29361132)","subcellular_location":"Nucleus; Chromosome","url":"https://www.uniprot.org/uniprotkb/Q9UGN5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PARP2","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"HIST2H2BE","stoichiometry":0.2},{"gene":"HMGN5","stoichiometry":0.2},{"gene":"MYO1E","stoichiometry":0.2},{"gene":"NUMA1","stoichiometry":0.2},{"gene":"PARP1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PARP2","total_profiled":1310},"omim":[{"mim_id":"616614","title":"HISTONE PARYLATION FACTOR 1; HPF1","url":"https://www.omim.org/entry/616614"},{"mim_id":"607725","title":"POLY(ADP-RIBOSE) POLYMERASE 2; PARP2","url":"https://www.omim.org/entry/607725"},{"mim_id":"173870","title":"POLY(ADP-RIBOSE) POLYMERASE 1; PARP1","url":"https://www.omim.org/entry/173870"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Nucleoli","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PARP2"},"hgnc":{"alias_symbol":["ARTD2"],"prev_symbol":["ADPRTL2"]},"alphafold":{"accession":"Q9UGN5","domains":[{"cath_id":"-","chopping":"88-210","consensus_level":"medium","plddt":89.4702,"start":88,"end":210},{"cath_id":"1.20.142.10","chopping":"234-366","consensus_level":"medium","plddt":90.2562,"start":234,"end":366},{"cath_id":"3.90.228.10","chopping":"367-580","consensus_level":"high","plddt":96.2295,"start":367,"end":580}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UGN5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UGN5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UGN5-F1-predicted_aligned_error_v6.png","plddt_mean":82.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PARP2","jax_strain_url":"https://www.jax.org/strain/search?query=PARP2"},"sequence":{"accession":"Q9UGN5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UGN5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UGN5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UGN5"}},"corpus_meta":[{"pmid":"23118055","id":"PMC_23118055","title":"Trapping of PARP1 and PARP2 by Clinical PARP Inhibitors.","date":"2012","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/23118055","citation_count":1796,"is_preprint":false},{"pmid":"10364231","id":"PMC_10364231","title":"PARP-2, A novel mammalian DNA damage-dependent poly(ADP-ribose) polymerase.","date":"1999","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10364231","citation_count":633,"is_preprint":false},{"pmid":"11948190","id":"PMC_11948190","title":"Poly(ADP-ribose) polymerase-2 (PARP-2) is required for efficient base excision DNA repair in association with PARP-1 and XRCC1.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11948190","citation_count":577,"is_preprint":false},{"pmid":"12727891","id":"PMC_12727891","title":"Functional interaction between PARP-1 and PARP-2 in chromosome stability and embryonic development in mouse.","date":"2003","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/12727891","citation_count":511,"is_preprint":false},{"pmid":"22921416","id":"PMC_22921416","title":"The role of PARP-1 and PARP-2 enzymes in metabolic regulation and disease.","date":"2012","source":"Cell metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/22921416","citation_count":255,"is_preprint":false},{"pmid":"25017100","id":"PMC_25017100","title":"Poly(ADP-ribose) polymerases in double-strand break repair: focus on PARP1, PARP2 and PARP3.","date":"2014","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/25017100","citation_count":249,"is_preprint":false},{"pmid":"24928857","id":"PMC_24928857","title":"PARP-2 and PARP-3 are selectively activated by 5' phosphorylated DNA breaks through an allosteric regulatory mechanism shared with PARP-1.","date":"2014","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/24928857","citation_count":232,"is_preprint":false},{"pmid":"21459329","id":"PMC_21459329","title":"PARP-2 regulates SIRT1 expression and whole-body energy expenditure.","date":"2011","source":"Cell metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/21459329","citation_count":223,"is_preprint":false},{"pmid":"29467415","id":"PMC_29467415","title":"PARP1 and PARP2 stabilise replication forks at base excision repair intermediates through Fbh1-dependent Rad51 regulation.","date":"2018","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/29467415","citation_count":195,"is_preprint":false},{"pmid":"15279798","id":"PMC_15279798","title":"PARP-1, PARP-2 and ATM in the DNA damage response: functional synergy in mouse development.","date":"2004","source":"DNA repair","url":"https://pubmed.ncbi.nlm.nih.gov/15279798","citation_count":190,"is_preprint":false},{"pmid":"27965414","id":"PMC_27965414","title":"Overlapping roles for PARP1 and PARP2 in the recruitment of endogenous XRCC1 and PNKP into oxidized chromatin.","date":"2017","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/27965414","citation_count":166,"is_preprint":false},{"pmid":"15615785","id":"PMC_15615785","title":"PARP-1 and PARP-2 interact with nucleophosmin/B23 and accumulate in transcriptionally active nucleoli.","date":"2005","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/15615785","citation_count":163,"is_preprint":false},{"pmid":"14749375","id":"PMC_14749375","title":"Functional interaction between poly(ADP-Ribose) polymerase 2 (PARP-2) and TRF2: PARP activity negatively regulates TRF2.","date":"2004","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/14749375","citation_count":155,"is_preprint":false},{"pmid":"19364882","id":"PMC_19364882","title":"Parp1 facilitates alternative NHEJ, whereas Parp2 suppresses IgH/c-myc translocations during immunoglobulin class switch recombination.","date":"2009","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/19364882","citation_count":147,"is_preprint":false},{"pmid":"25501596","id":"PMC_25501596","title":"PARP-2 sustains erythropoiesis in mice by limiting replicative stress in erythroid progenitors.","date":"2014","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/25501596","citation_count":141,"is_preprint":false},{"pmid":"30104678","id":"PMC_30104678","title":"PARP2 mediates branched poly ADP-ribosylation in response to DNA damage.","date":"2018","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/30104678","citation_count":137,"is_preprint":false},{"pmid":"24757201","id":"PMC_24757201","title":"MicroRNA-149 inhibits PARP-2 and promotes mitochondrial biogenesis via SIRT-1/PGC-1α network in skeletal muscle.","date":"2014","source":"Diabetes","url":"https://pubmed.ncbi.nlm.nih.gov/24757201","citation_count":128,"is_preprint":false},{"pmid":"20388209","id":"PMC_20388209","title":"Investigation of PARP-1, PARP-2, and PARG interactomes by affinity-purification mass spectrometry.","date":"2010","source":"Proteome science","url":"https://pubmed.ncbi.nlm.nih.gov/20388209","citation_count":124,"is_preprint":false},{"pmid":"21968702","id":"PMC_21968702","title":"PARP-1 and PARP-2: New players in tumour development.","date":"2011","source":"American journal of cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/21968702","citation_count":122,"is_preprint":false},{"pmid":"23678004","id":"PMC_23678004","title":"Parp-2 is required to maintain hematopoiesis following sublethal γ-irradiation in mice.","date":"2013","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/23678004","citation_count":122,"is_preprint":false},{"pmid":"16946705","id":"PMC_16946705","title":"PARP-2 deficiency affects the survival of CD4+CD8+ double-positive thymocytes.","date":"2006","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/16946705","citation_count":119,"is_preprint":false},{"pmid":"32939087","id":"PMC_32939087","title":"Bridging of DNA breaks activates PARP2-HPF1 to modify chromatin.","date":"2020","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/32939087","citation_count":114,"is_preprint":false},{"pmid":"34570508","id":"PMC_34570508","title":"Discovery of 5-{4-[(7-Ethyl-6-oxo-5,6-dihydro-1,5-naphthyridin-3-yl)methyl]piperazin-1-yl}-N-methylpyridine-2-carboxamide (AZD5305): A PARP1-DNA Trapper with High Selectivity for PARP1 over PARP2 and Other PARPs.","date":"2021","source":"Journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/34570508","citation_count":108,"is_preprint":false},{"pmid":"14751510","id":"PMC_14751510","title":"PARP-1, PARP-2, and the cellular response to low doses of ionizing radiation.","date":"2004","source":"International journal of radiation oncology, biology, physics","url":"https://pubmed.ncbi.nlm.nih.gov/14751510","citation_count":108,"is_preprint":false},{"pmid":"29361132","id":"PMC_29361132","title":"Characterization of DNA ADP-ribosyltransferase activities of PARP2 and PARP3: new insights into DNA ADP-ribosylation.","date":"2018","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/29361132","citation_count":106,"is_preprint":false},{"pmid":"34066057","id":"PMC_34066057","title":"PARP Power: A Structural Perspective on PARP1, PARP2, and PARP3 in DNA Damage Repair and Nucleosome Remodelling.","date":"2021","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/34066057","citation_count":99,"is_preprint":false},{"pmid":"26673720","id":"PMC_26673720","title":"Single molecule detection of PARP1 and PARP2 interaction with DNA strand breaks and their poly(ADP-ribosyl)ation using high-resolution AFM imaging.","date":"2015","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/26673720","citation_count":96,"is_preprint":false},{"pmid":"31266892","id":"PMC_31266892","title":"Selective targeting of PARP-2 inhibits androgen receptor signaling and prostate cancer growth through disruption of FOXA1 function.","date":"2019","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/31266892","citation_count":92,"is_preprint":false},{"pmid":"11358842","id":"PMC_11358842","title":"Novel inhibitors of poly(ADP-ribose) polymerase/PARP1 and PARP2 identified using a cell-based screen in yeast.","date":"2001","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/11358842","citation_count":89,"is_preprint":false},{"pmid":"26704974","id":"PMC_26704974","title":"PARP-2 domain requirements for DNA damage-dependent activation and localization to sites of DNA damage.","date":"2015","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/26704974","citation_count":85,"is_preprint":false},{"pmid":"33275888","id":"PMC_33275888","title":"The Oncogenic Helicase ALC1 Regulates PARP Inhibitor Potency by Trapping PARP2 at DNA Breaks.","date":"2020","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/33275888","citation_count":82,"is_preprint":false},{"pmid":"20092359","id":"PMC_20092359","title":"Crystal structure of the catalytic domain of human PARP2 in complex with PARP inhibitor ABT-888.","date":"2010","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20092359","citation_count":71,"is_preprint":false},{"pmid":"25757679","id":"PMC_25757679","title":"Olaparib: an oral PARP-1 and PARP-2 inhibitor with promising activity in ovarian cancer.","date":"2015","source":"Future oncology (London, England)","url":"https://pubmed.ncbi.nlm.nih.gov/25757679","citation_count":65,"is_preprint":false},{"pmid":"21228215","id":"PMC_21228215","title":"Poly(ADP-ribose) polymerases PARP1 and PARP2 modulate topoisomerase II beta (TOP2B) function during chromatin condensation in mouse spermiogenesis.","date":"2011","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/21228215","citation_count":59,"is_preprint":false},{"pmid":"34108479","id":"PMC_34108479","title":"Activation of PARP2/ARTD2 by DNA damage induces conformational changes relieving enzyme autoinhibition.","date":"2021","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/34108479","citation_count":58,"is_preprint":false},{"pmid":"23357680","id":"PMC_23357680","title":"Interaction of PARP-2 with DNA structures mimicking DNA repair intermediates and consequences on activity of base excision repair proteins.","date":"2013","source":"Biochimie","url":"https://pubmed.ncbi.nlm.nih.gov/23357680","citation_count":58,"is_preprint":false},{"pmid":"32046278","id":"PMC_32046278","title":"Immunomodulatory Roles of PARP-1 and PARP-2: Impact on PARP-Centered Cancer Therapies.","date":"2020","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/32046278","citation_count":57,"is_preprint":false},{"pmid":"30321391","id":"PMC_30321391","title":"Structural basis for DNA break recognition by ARTD2/PARP2.","date":"2018","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/30321391","citation_count":56,"is_preprint":false},{"pmid":"18676401","id":"PMC_18676401","title":"The histone subcode: poly(ADP-ribose) polymerase-1 (Parp-1) and Parp-2 control cell differentiation by regulating the transcriptional intermediary factor TIF1beta and the heterochromatin protein HP1alpha.","date":"2008","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/18676401","citation_count":55,"is_preprint":false},{"pmid":"16288880","id":"PMC_16288880","title":"Discovery of potent and selective PARP-1 and PARP-2 inhibitors: SBDD analysis via a combination of X-ray structural study and homology modeling.","date":"2005","source":"Bioorganic & medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16288880","citation_count":55,"is_preprint":false},{"pmid":"15959455","id":"PMC_15959455","title":"Differential effect of PARP-2 deletion on brain injury after focal and global cerebral ischemia.","date":"2006","source":"Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/15959455","citation_count":53,"is_preprint":false},{"pmid":"18436469","id":"PMC_18436469","title":"Identification of lysines 36 and 37 of PARP-2 as targets for acetylation and auto-ADP-ribosylation.","date":"2008","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/18436469","citation_count":50,"is_preprint":false},{"pmid":"16461352","id":"PMC_16461352","title":"PARP-2 interacts with TTF-1 and regulates expression of surfactant protein-B.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16461352","citation_count":49,"is_preprint":false},{"pmid":"33649352","id":"PMC_33649352","title":"The contribution of PARP1, PARP2 and poly(ADP-ribosyl)ation to base excision repair in the nucleosomal context.","date":"2021","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/33649352","citation_count":48,"is_preprint":false},{"pmid":"26432600","id":"PMC_26432600","title":"MicroRNA expression and protein acetylation pattern in respiratory and limb muscles of Parp-1(-/-) and Parp-2(-/-) mice with lung cancer cachexia.","date":"2015","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/26432600","citation_count":47,"is_preprint":false},{"pmid":"27725894","id":"PMC_27725894","title":"Understanding specific functions of PARP-2: new lessons for cancer therapy.","date":"2016","source":"American journal of cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/27725894","citation_count":46,"is_preprint":false},{"pmid":"24510188","id":"PMC_24510188","title":"ARTD2 activity is stimulated by RNA.","date":"2014","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/24510188","citation_count":44,"is_preprint":false},{"pmid":"35349716","id":"PMC_35349716","title":"PARP inhibitors trap PARP2 and alter the mode of recruitment of PARP2 at DNA damage sites.","date":"2022","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/35349716","citation_count":42,"is_preprint":false},{"pmid":"11133988","id":"PMC_11133988","title":"A bidirectional promoter connects the poly(ADP-ribose) polymerase 2 (PARP-2) gene to the gene for RNase P RNA. structure and expression of the mouse PARP-2 gene.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11133988","citation_count":42,"is_preprint":false},{"pmid":"27708353","id":"PMC_27708353","title":"Characterization of the DNA dependent activation of human ARTD2/PARP2.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/27708353","citation_count":40,"is_preprint":false},{"pmid":"29036662","id":"PMC_29036662","title":"PARP2 controls double-strand break repair pathway choice by limiting 53BP1 accumulation at DNA damage sites and promoting end-resection.","date":"2017","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/29036662","citation_count":40,"is_preprint":false},{"pmid":"19422384","id":"PMC_19422384","title":"Selective PARP-2 inhibitors increase apoptosis in hippocampal slices but protect cortical cells in models of post-ischaemic brain damage.","date":"2009","source":"British journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/19422384","citation_count":40,"is_preprint":false},{"pmid":"36961901","id":"PMC_36961901","title":"Clinical PARP inhibitors allosterically induce PARP2 retention on DNA.","date":"2023","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/36961901","citation_count":39,"is_preprint":false},{"pmid":"31340767","id":"PMC_31340767","title":"Long non-coding RNA PTTG3P functions as an oncogene by sponging miR-383 and up-regulating CCND1 and PARP2 in hepatocellular carcinoma.","date":"2019","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/31340767","citation_count":39,"is_preprint":false},{"pmid":"34580230","id":"PMC_34580230","title":"Deficiency of PARP-1 and PARP-2 in the mouse uterus results in decidualization failure and pregnancy loss.","date":"2021","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/34580230","citation_count":39,"is_preprint":false},{"pmid":"33141820","id":"PMC_33141820","title":"Bridging of nucleosome-proximal DNA double-strand breaks by PARP2 enhances its interaction with HPF1.","date":"2020","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/33141820","citation_count":38,"is_preprint":false},{"pmid":"31129062","id":"PMC_31129062","title":"A Single-Molecule Atomic Force Microscopy Study of PARP1 and PARP2 Recognition of Base Excision Repair DNA Intermediates.","date":"2019","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/31129062","citation_count":38,"is_preprint":false},{"pmid":"35430559","id":"PMC_35430559","title":"Selective degradation of PARP2 by PROTACs via recruiting DCAF16 for triple-negative breast cancer.","date":"2022","source":"European journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/35430559","citation_count":38,"is_preprint":false},{"pmid":"30996287","id":"PMC_30996287","title":"Coordinated signals from the DNA repair enzymes PARP-1 and PARP-2 promotes B-cell development and function.","date":"2019","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/30996287","citation_count":38,"is_preprint":false},{"pmid":"24365238","id":"PMC_24365238","title":"Deletion of PARP-2 induces hepatic cholesterol accumulation and decrease in HDL levels.","date":"2013","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/24365238","citation_count":38,"is_preprint":false},{"pmid":"32221289","id":"PMC_32221289","title":"Differential regulation of breast cancer bone metastasis by PARP1 and PARP2.","date":"2020","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/32221289","citation_count":36,"is_preprint":false},{"pmid":"25724268","id":"PMC_25724268","title":"Interaction of PARP-2 with AP site containing DNA.","date":"2015","source":"Biochimie","url":"https://pubmed.ncbi.nlm.nih.gov/25724268","citation_count":35,"is_preprint":false},{"pmid":"34359075","id":"PMC_34359075","title":"Distinct roles for PARP-1 and PARP-2 in c-Myc-driven B-cell lymphoma in mice.","date":"2022","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/34359075","citation_count":31,"is_preprint":false},{"pmid":"34732825","id":"PMC_34732825","title":"Dual function of HPF1 in the modulation of PARP1 and PARP2 activities.","date":"2021","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/34732825","citation_count":29,"is_preprint":false},{"pmid":"30541899","id":"PMC_30541899","title":"miR-125 regulates PI3K/Akt/mTOR signaling pathway in rheumatoid arthritis rats via PARP2.","date":"2019","source":"Bioscience reports","url":"https://pubmed.ncbi.nlm.nih.gov/30541899","citation_count":29,"is_preprint":false},{"pmid":"28303528","id":"PMC_28303528","title":"Human mass balance study and metabolite profiling of 14C-niraparib, a novel poly(ADP-Ribose) polymerase (PARP)-1 and PARP-2 inhibitor, in patients with advanced cancer.","date":"2017","source":"Investigational new drugs","url":"https://pubmed.ncbi.nlm.nih.gov/28303528","citation_count":28,"is_preprint":false},{"pmid":"29236322","id":"PMC_29236322","title":"microRNA-383 suppresses the PI3K-AKT-MTOR signaling pathway to inhibit development of cervical cancer via down-regulating PARP2.","date":"2018","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/29236322","citation_count":27,"is_preprint":false},{"pmid":"32001817","id":"PMC_32001817","title":"Coordinated signals from PARP-1 and PARP-2 are required to establish a proper T cell immune response to breast tumors in mice.","date":"2020","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/32001817","citation_count":27,"is_preprint":false},{"pmid":"21812934","id":"PMC_21812934","title":"Identification of candidate substrates for poly(ADP-ribose) polymerase-2 (PARP2) in the absence of DNA damage using high-density protein microarrays.","date":"2011","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/21812934","citation_count":25,"is_preprint":false},{"pmid":"21053069","id":"PMC_21053069","title":"Modulation of PARP-1 and PARP-2 expression by L-carnosine and trehalose after LPS and INFγ-induced oxidative stress.","date":"2010","source":"Neurochemical research","url":"https://pubmed.ncbi.nlm.nih.gov/21053069","citation_count":25,"is_preprint":false},{"pmid":"27300349","id":"PMC_27300349","title":"The clinicopathological significance of miR-149 and PARP-2 in hepatocellular carcinoma and their roles in chemo/radiotherapy.","date":"2016","source":"Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/27300349","citation_count":23,"is_preprint":false},{"pmid":"31829559","id":"PMC_31829559","title":"Nonspecific Binding of RNA to PARP1 and PARP2 Does Not Lead to Catalytic Activation.","date":"2019","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/31829559","citation_count":22,"is_preprint":false},{"pmid":"32423430","id":"PMC_32423430","title":"Different regulation of PARP1, PARP2, PARP3 and TRPM2 genes expression in acute myeloid leukemia cells.","date":"2020","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/32423430","citation_count":22,"is_preprint":false},{"pmid":"23261455","id":"PMC_23261455","title":"PARP-2 knockdown protects cardiomyocytes from hypertrophy via activation of SIRT1.","date":"2012","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/23261455","citation_count":22,"is_preprint":false},{"pmid":"25281201","id":"PMC_25281201","title":"Alpha-lipoic acid attenuates cardiac hypertrophy via downregulation of PARP-2 and subsequent activation of SIRT-1.","date":"2014","source":"European journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/25281201","citation_count":22,"is_preprint":false},{"pmid":"36594010","id":"PMC_36594010","title":"Dynamics of endogenous PARP1 and PARP2 during DNA damage revealed by live-cell single-molecule imaging.","date":"2022","source":"iScience","url":"https://pubmed.ncbi.nlm.nih.gov/36594010","citation_count":21,"is_preprint":false},{"pmid":"27373144","id":"PMC_27373144","title":"Common and unique genetic interactions of the poly(ADP-ribose) polymerases PARP1 and PARP2 with DNA double-strand break repair pathways.","date":"2016","source":"DNA repair","url":"https://pubmed.ncbi.nlm.nih.gov/27373144","citation_count":21,"is_preprint":false},{"pmid":"18587655","id":"PMC_18587655","title":"Role of PARP-1 and PARP-2 in the expression of apoptosis-regulating genes in HeLa cells.","date":"2008","source":"Cell biology and toxicology","url":"https://pubmed.ncbi.nlm.nih.gov/18587655","citation_count":21,"is_preprint":false},{"pmid":"21870269","id":"PMC_21870269","title":"Phenotypic characterization of Parp-1 and Parp-2 deficient mice and cells.","date":"2011","source":"Methods in molecular biology (Clifton, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/21870269","citation_count":21,"is_preprint":false},{"pmid":"38698556","id":"PMC_38698556","title":"Specific and shared biological functions of PARP2 - is PARP2 really a lil' brother of PARP1?","date":"2024","source":"Expert reviews in molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/38698556","citation_count":20,"is_preprint":false},{"pmid":"33925170","id":"PMC_33925170","title":"Functional Roles of PARP2 in Assembling Protein-Protein Complexes Involved in Base Excision DNA Repair.","date":"2021","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/33925170","citation_count":20,"is_preprint":false},{"pmid":"15517597","id":"PMC_15517597","title":"Co-localization of poly(ADPR)polymerase 1 (PARP-1) poly(ADPR)polymerase 2 (PARP-2) and related proteins in rat testis nuclear matrix defined by chemical cross-linking.","date":"2005","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15517597","citation_count":20,"is_preprint":false},{"pmid":"39383878","id":"PMC_39383878","title":"Inactive Parp2 causes Tp53-dependent lethal anemia by blocking replication-associated nick ligation in erythroblasts.","date":"2024","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/39383878","citation_count":18,"is_preprint":false},{"pmid":"37326017","id":"PMC_37326017","title":"The CSB chromatin remodeler regulates PARP1- and PARP2-mediated single-strand break repair at actively transcribed DNA regions.","date":"2023","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/37326017","citation_count":18,"is_preprint":false},{"pmid":"19607827","id":"PMC_19607827","title":"Parp2 is required for the differentiation of post-meiotic germ cells: identification of a spermatid-specific complex containing Parp1, Parp2, TP2 and HSPA2.","date":"2009","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/19607827","citation_count":18,"is_preprint":false},{"pmid":"38565848","id":"PMC_38565848","title":"PARP2 promotes Break Induced Replication-mediated telomere fragility in response to replication stress.","date":"2024","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/38565848","citation_count":17,"is_preprint":false},{"pmid":"32373627","id":"PMC_32373627","title":"Molecular Mechanism of Selective Binding of NMS-P118 to PARP-1 and PARP-2: A Computational Perspective.","date":"2020","source":"Frontiers in molecular biosciences","url":"https://pubmed.ncbi.nlm.nih.gov/32373627","citation_count":17,"is_preprint":false},{"pmid":"38823186","id":"PMC_38823186","title":"The dynamics and regulation of PARP1 and PARP2 in response to DNA damage and during replication.","date":"2024","source":"DNA repair","url":"https://pubmed.ncbi.nlm.nih.gov/38823186","citation_count":16,"is_preprint":false},{"pmid":"26700152","id":"PMC_26700152","title":"Reduced tumor burden through increased oxidative stress in lung adenocarcinoma cells of PARP-1 and PARP-2 knockout mice.","date":"2015","source":"Biochimie","url":"https://pubmed.ncbi.nlm.nih.gov/26700152","citation_count":16,"is_preprint":false},{"pmid":"23291187","id":"PMC_23291187","title":"PARP-2 regulates cell cycle-related genes through histone deacetylation and methylation independently of poly(ADP-ribosyl)ation.","date":"2013","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/23291187","citation_count":16,"is_preprint":false},{"pmid":"32046043","id":"PMC_32046043","title":"Silencing of PARP2 Blocks Autophagic Degradation.","date":"2020","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/32046043","citation_count":15,"is_preprint":false},{"pmid":"32383115","id":"PMC_32383115","title":"Impact of PARP1, PARP2 & PARP3 on the Base Excision Repair of Nucleosomal DNA.","date":"2020","source":"Advances in experimental medicine and biology","url":"https://pubmed.ncbi.nlm.nih.gov/32383115","citation_count":15,"is_preprint":false},{"pmid":"37216533","id":"PMC_37216533","title":"Single-molecule force spectroscopy reveals binding and bridging dynamics of PARP1 and PARP2 at DNA double-strand breaks.","date":"2023","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/37216533","citation_count":15,"is_preprint":false},{"pmid":"36171229","id":"PMC_36171229","title":"Synthesis, biological evaluation, and molecular modeling studies of new benzoxazole derivatives as PARP-2 inhibitors targeting breast cancer.","date":"2022","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/36171229","citation_count":14,"is_preprint":false},{"pmid":"32633392","id":"PMC_32633392","title":"Hsa-circ-0068566 inhibited the development of myocardial ischemia reperfusion injury by regulating hsa-miR-6322/PARP2 signal pathway.","date":"2020","source":"European review for medical and pharmacological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/32633392","citation_count":13,"is_preprint":false},{"pmid":"19806447","id":"PMC_19806447","title":"LMTK2 and PARP-2 gene polymorphism and azoospermia secondary to meiotic arrest.","date":"2009","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19806447","citation_count":13,"is_preprint":false},{"pmid":"34051087","id":"PMC_34051087","title":"miRNA-149 targets PARP-2 in endometrial epithelial and stromal cells to regulate the trophoblast attachment process.","date":"2021","source":"Molecular human reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/34051087","citation_count":13,"is_preprint":false},{"pmid":"29016348","id":"PMC_29016348","title":"PARP-1 and PARP-2 activity in cancer-induced cachexia: potential therapeutic implications.","date":"2018","source":"Biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/29016348","citation_count":12,"is_preprint":false},{"pmid":"25336152","id":"PMC_25336152","title":"PARP-2 depletion results in lower radiation cell survival but cell line-specific differences in poly(ADP-ribose) levels.","date":"2014","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/25336152","citation_count":12,"is_preprint":false},{"pmid":"35000531","id":"PMC_35000531","title":"Long non-coding RNA CCL2 promoted gastric cancer function via miR-128/ PARP2 signal pathway.","date":"2022","source":"Bioengineered","url":"https://pubmed.ncbi.nlm.nih.gov/35000531","citation_count":11,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":48898,"output_tokens":10933,"usd":0.155344,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":21741,"output_tokens":7689,"usd":0.150465,"stage2_stop_reason":"end_turn"},"total_usd":0.305809,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1999,\n      \"finding\": \"PARP-2 is a damaged DNA-binding protein that catalyzes poly(ADP-ribose) polymer formation in a DNA-dependent manner and undergoes automodification; it is localized in the nucleus and accounts for residual poly(ADP-ribose) synthesis in PARP-1-deficient cells.\",\n      \"method\": \"Recombinant protein purification, in vitro DNA-binding assay, in vitro PAR synthesis assay, nuclear localization by cell fractionation/immunofluorescence\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro reconstitution of enzymatic activity with purified recombinant protein, replicated across multiple assays in a single rigorous study\",\n      \"pmids\": [\"10364231\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"PARP-2 homo- and heterodimerizes with PARP-1 (with interacting interfaces mapped and being sites of reciprocal ADP-ribosylation), and physically interacts with BER proteins XRCC1, DNA polymerase β, and DNA ligase III. XRCC1 negatively regulates PARP-2 activity while serving as a polymer acceptor. PARP-2-deficient cells show delayed DNA strand-break resealing after alkylating agent treatment, confirming a role in BER.\",\n      \"method\": \"Co-immunoprecipitation, in vitro pulldown, PARP activity assays, gene knockout mouse model (MNU treatment), comet assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, mapped interaction interfaces, loss-of-function mouse model with defined repair phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"11948190\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"PARP-2-deficient mice are sensitive to ionizing radiation; PARP-2-/- MEFs show post-replicative genomic instability, G2/M accumulation, chromosome mis-segregation with kinetochore defects after alkylating agent treatment. Combined PARP-1/PARP-2 double knockout is lethal at gastrulation, demonstrating overlapping essential functions. Female-specific lethality in PARP-1+/-PARP-2-/- mice is linked to X chromosome instability.\",\n      \"method\": \"Gene knockout mouse models, metaphase chromosome analysis, flow cytometry, irradiation survival assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic loss-of-function with specific cytogenetic and developmental phenotypes, replicated across multiple genotypes\",\n      \"pmids\": [\"12727891\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PARP-2 physically binds to the telomere-protective protein TRF2 via the N-terminal domain of PARP-2 and the myb domain of TRF2. PARP activity covalently heteromodifies TRF2's dimerization domain and non-covalently modifies its myb domain via PAR binding, negatively regulating TRF2 DNA-binding activity. PARP-2-/- cells display spontaneously increased chromosome/chromatid breaks and telomere ends lacking TTAGGG repeats.\",\n      \"method\": \"Co-immunoprecipitation, in vitro pulldown, colocalization studies, ADP-ribosylation assays, telomere FISH on PARP-2-/- cells\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP with domain mapping, functional modification assay, knockout cellular phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"14749375\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"PARP-2 accumulates in the nucleolus and partially colocalizes with nucleophosmin/B23. PARP-2 interacts with B23 through its N-terminal DNA-binding domain via a constitutive association that does not depend on PARP activity or ribosomal transcription. A nuclear localization signal and nucleolar localization signal were identified in the N-terminal domain. PARP-1 and PARP-2 are delocalized from the nucleolus upon RNA polymerase I inhibition.\",\n      \"method\": \"Immunofluorescence, co-immunoprecipitation, NLS/NoLS mutagenesis, RNA pol I inhibition experiments, PARP-1/2-deficient MEFs\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct localization with functional NLS/NoLS mutagenesis, Co-IP, and loss-of-function validation in knockout cells\",\n      \"pmids\": [\"15615785\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"PARP-2 interacts with thyroid transcription factor-1 (TTF-1) via the E (catalytic) domain of PARP-2 and the C-terminal domain of TTF-1; both PARP-2 and PARP-1 enhance the activity of the surfactant protein-B (Sftpb) gene promoter in vitro. PARP-2 is selectively expressed in fetal mouse lung epithelial cells.\",\n      \"method\": \"Co-immunoprecipitation with mass spectrometry identification, GST pulldown domain mapping, luciferase reporter assay, immunohistochemistry\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with MS validation, domain mapping pulldown, functional reporter assay, single lab\",\n      \"pmids\": [\"16461352\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PARP-2 binds TIF1β with high affinity both directly and through HP1α; Parp-2 and its activity are required for relocation of TIF1β to heterochromatic foci during primitive endodermal differentiation. Both PARP-1 and PARP-2 selectively poly(ADP-ribosyl)ate HP1α. PARP-2 binds HP1β but not HP1γ, whereas PARP-1 binds weakly to TIF1β and HP1β only.\",\n      \"method\": \"Co-immunoprecipitation, pulldown assays, in vitro ADP-ribosylation, shRNA knockdown, immunofluorescence colocalization, differentiation assays\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, in vitro enzymatic assay, shRNA loss-of-function with differentiation phenotype, single lab\",\n      \"pmids\": [\"18676401\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Lysines 36 and 37 in the nuclear localization signal of PARP-2 are acetylated by histone acetyltransferases PCAF and GCN5L in vitro and in vivo. Acetylation at these residues reduces PARP-2 DNA-binding activity and enzymatic ADP-ribosylation activity, and reduces auto-mono-ADP-ribosylation.\",\n      \"method\": \"In vitro acetyltransferase assay, site-directed mutagenesis (K36A, K37A), DNA-binding assay, auto-ADP-ribosylation assay, in vivo co-immunoprecipitation\",\n      \"journal\": \"The international journal of biochemistry & cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — site-directed mutagenesis combined with in vitro enzymatic assays and in vivo validation, multiple orthogonal methods in one study\",\n      \"pmids\": [\"18436469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"During immunoglobulin class switch recombination, Parp2 actively suppresses IgH/c-myc translocations, functioning as a translocation suppressor. Parp1 facilitates alternative (microhomology-mediated) end-joining. Neither Parp1 nor Parp2 is required for CSR per se, but Parp enzymatic activity is induced in an AID-dependent manner during CSR.\",\n      \"method\": \"Parp1/Parp2 knockout mouse B cells, CSR assays, translocation frequency analysis by PCR/Southern blot, ADP-ribose detection\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic knockouts with specific chromosomal translocation phenotype, epistasis with AID\",\n      \"pmids\": [\"19364882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Parp2 is required for spermiogenesis; Parp2 interacts with transition protein TP2 and chaperone HSPA2 (Parp2-TP2 interaction partially mediated by poly(ADP-ribosyl)ation). Only Parp1 poly(ADP-ribosyl)ates HSPA2. A Parp1/Parp2/TP2/HSPA2 spermatid-specific complex was identified. Parp2 deficiency causes loss of TP2-expressing spermatids, defective chromatin condensation, and abnormal manchette microtubule formation.\",\n      \"method\": \"In vitro protein-protein interaction assays, ADP-ribosylation assays, immunohistochemistry, electron microscopy on Parp2-/- mouse testes\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct protein interaction assays with enzymatic validation, loss-of-function mouse model with ultrastructural phenotype\",\n      \"pmids\": [\"19607827\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Crystal structures of the catalytic domain of human PARP2 in complex with inhibitors 3-aminobenzamide and ABT-888 were determined, revealing structural features of the NAD+ binding site and enabling comparison with PARP1 for selective inhibitor design.\",\n      \"method\": \"X-ray crystallography\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — high-resolution crystal structure, single study\",\n      \"pmids\": [\"20092359\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PARP-2 acts as a direct transcriptional repressor of the SIRT1 promoter. PARP-2 deficiency increases SIRT1 expression and activity in myotubes (not via changes in NAD+ levels), promotes energy expenditure, increases mitochondrial content, and protects against diet-induced obesity in mice; however, PARP-2-/- mice are glucose intolerant due to defective pancreatic β-cell function.\",\n      \"method\": \"PARP-2 knockout mouse model, siRNA knockdown in myotubes, SIRT1 promoter reporter assay, ChIP, metabolic phenotyping, NAD+ measurements\",\n      \"journal\": \"Cell metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct promoter binding by ChIP, reporter assay, knockout mouse with defined metabolic phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"21459329\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PARP1 and PARP2 modulate topoisomerase II beta (TOP2B) activity during spermiogenesis: PARP1 and PARP2 activity strongly inhibits TOP2B in vitro, and this inhibition is counteracted by PAR glycohydrolase activity. Genetic and pharmacological PARP inhibition both increase TOP2B covalent DNA binding in vivo in spermatids.\",\n      \"method\": \"In vitro TOP2B activity assay with purified PARP1/PARP2, pharmacological PARP inhibition in mice, genetic PARP knockout mice, TOP2B-DNA complex assay in spermatids\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of PARP-mediated TOP2B inhibition, corroborated by in vivo genetic and pharmacological experiments\",\n      \"pmids\": [\"21228215\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PARP inhibitors trap PARP1 and PARP2 at damaged DNA, forming cytotoxic PARP-DNA complexes. The trapping potency differs among inhibitors (niraparib > olaparib >> veliparib) and does not correlate with catalytic inhibitory potency. Homologous recombination, post-replication repair, Fanconi anemia pathway, polymerase β, and FEN1 are critical for repairing trapped PARP-DNA complexes.\",\n      \"method\": \"Cellular PARP trapping assay, clonogenic survival, 30 genetically defined DT40 cell lines with specific DNA repair gene deletions\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — systematic genetic epistasis across 30 cell lines, quantitative trapping assays, multiple orthogonal approaches\",\n      \"pmids\": [\"23118055\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PARP-2 interacts with AP site-containing DNA via Schiff base formation through its N-terminal domain. PARP-2, like PARP-1, inhibits APE1 activity by binding to AP sites, but unlike PARP-1, this inhibitory effect is not regulated by PAR synthesis. PARP-2 DNA binding is not modulated by autoPARylation.\",\n      \"method\": \"EMSA, cross-linking assays, APE1 activity assay in presence of PARP-2\",\n      \"journal\": \"Biochimie\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple in vitro biochemical assays, single lab, no in vivo confirmation\",\n      \"pmids\": [\"25724268\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PARP-2 interacts with and inhibits both DNA polymerase β and FEN1 in vitro. Unlike PARP-1, poly(ADP-ribosyl)ation by PARP-2 does not restore DNA pol β or FEN1 activity. PARP-2 can also modulate the poly(ADP-ribosyl)ation activity of PARP-1, decreasing it. PARP-2 shows highest affinity for flap-containing DNA but is most efficiently activated by 5'-overhang DNA.\",\n      \"method\": \"EMSA for DNA binding (Kd measurements), in vitro BER enzyme activity assays (pol β, FEN1), PAR synthesis assays\",\n      \"journal\": \"Biochimie\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple in vitro biochemical assays with quantitative measurements, single lab\",\n      \"pmids\": [\"23357680\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PARP-2 is a direct transcriptional suppressor of the SREBP1 promoter in a manner dependent on its enzymatic activity. PARP-2 deletion increases hepatic SREBP1 expression, inducing downstream lipogenic genes and resulting in higher hepatic cholesterol content and decreased serum HDL levels in mice.\",\n      \"method\": \"PARP-2 knockout mice, siRNA knockdown in HepG2 cells, promoter reporter assay, gene expression analysis, lipid measurements\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — promoter reporter assay, knockout mouse metabolic phenotype, single lab\",\n      \"pmids\": [\"24365238\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PARP-2 (and PARP-3) are selectively activated by DNA breaks harboring a 5' phosphate group, suggesting activation by specific DNA repair intermediates competent for ligation. The WGR domain is the central regulatory domain of PARP-2, not the N-terminal region (NTR). PARP-1, PARP-2, and PARP-3 share an allosteric activation mechanism involving local destabilization of the catalytic domain upon DNA binding.\",\n      \"method\": \"Biochemical activation assays with defined DNA substrates, domain deletion/mutagenesis analysis, in vitro PAR synthesis assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — systematic in vitro reconstitution with substrate specificity analysis and domain mutagenesis, multiple orthogonal methods\",\n      \"pmids\": [\"24928857\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"ARTD2/PARP2 is activated by RNA in addition to DNA. RNA binding is mediated by the N-terminal SAP domain. In cells, this RNA-stimulated ARTD2 activation contributes to increased PAR formation under combined genotoxic + RNA-accumulating conditions, predominantly through ARTD2 rather than ARTD1.\",\n      \"method\": \"In vitro PAR synthesis assay with RNA substrates, domain deletion analysis (SAP domain), siRNA knockdown in cells, Actinomycin D co-treatment experiments\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro reconstitution plus cellular knockdown validation, single lab\",\n      \"pmids\": [\"24510188\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PARP-2 deletion in mice causes chronic anemia due to shortened erythrocyte lifespan and impaired erythroid progenitor differentiation. PARP-2 deficiency triggers replicative stress in erythroblasts (γ-H2AX accumulation in S-phase, CHK1/RPA phosphorylation, micronuclei), activating p53-dependent DNA damage response, G2/M arrest, and apoptosis. Loss of pro-apoptotic Puma restores hematocrit; loss of p21 causes perinatal death by exacerbating erythropoiesis defects.\",\n      \"method\": \"PARP-2 knockout mice, flow cytometry, γ-H2AX staining, CHK1/RPA phosphorylation assays, genetic epistasis with Puma and p21 knockout\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean loss-of-function with defined cellular phenotype, genetic epistasis with multiple downstream effectors\",\n      \"pmids\": [\"25501596\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"miR-149 directly inhibits PARP-2 expression, increasing cellular NAD+ and SIRT1 activity, which promotes mitochondrial biogenesis via PGC-1α activation. PARP-2 knockdown in skeletal muscle myotubes recapitulates miR-149 overexpression effects on SIRT1/PGC-1α pathway.\",\n      \"method\": \"miR-149 overexpression in myotubes, PARP-2 knockdown, NAD+ measurement, SIRT1 activity assay, PGC-1α and mitochondrial marker analysis\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with pathway readouts, single lab, mechanistic chain validated with multiple markers\",\n      \"pmids\": [\"24757201\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"All three domains of PARP-2 (NTR, WGR, CAT) collectively contribute to DNA damage interaction. The NTR is natively disordered and is required for activation on specific DNA damage types but is not essential for PARP-2 localization to DNA damage sites. The WGR and CAT domains together recruit PARP-2 to DNA breaks.\",\n      \"method\": \"Biophysical analyses (SAXS/SEC-MALS indicating NTR disorder), structural studies, DNA-binding assays, live-cell laser micro-irradiation localization with domain deletion mutants, in vitro PAR synthesis assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — structural characterization combined with biochemical and live-cell localization assays using domain deletion mutants, multiple orthogonal methods\",\n      \"pmids\": [\"26704974\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PARP2 preferentially and specifically recognizes single DNA nicks (low binding to undamaged DNA or DSBs), and activation by SSBs drives synthesis of highly branched PAR. PARP1 has broader affinity (nicks and DSBs). PARP2 in dimeric form is more effective at PAR synthesis than monomer, opposite to PARP1. PARP2 suppresses PAR synthesis by PARP1 after SSB formation.\",\n      \"method\": \"Single-molecule AFM imaging, fluorescence titration, PAR synthesis biochemical assay with defined DNA substrates\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — single-molecule AFM with biochemical corroboration, multiple substrate types tested, two independent methodological approaches\",\n      \"pmids\": [\"26673720\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The WGR domain of PARP2 is the key domain for DNA break detection; crystal structures of the ARTD2 WGR domain bound to DSB-mimicking DNA reveal end-to-end DNA interaction mode, how PARP2 recognizes nicked DNA and the 5'-phosphate group, and how it mediates DNA end joining in vitro. Mutagenesis of the WGR-DNA interface confirms WGR is critical for DNA binding and catalytic activation.\",\n      \"method\": \"X-ray crystallography, site-directed mutagenesis, in vitro activity assays, DNA-binding assays, stoichiometry measurements\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with extensive mutagenesis and biochemical validation, multiple orthogonal methods\",\n      \"pmids\": [\"30321391\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"PARP-2 contains transcriptional repression activity independent of its enzymatic activity, recruiting HDAC5, HDAC7, and histone methyltransferase G9a to promoters of cell cycle-related genes and generating repressive chromatin marks (histone deacetylation and methylation).\",\n      \"method\": \"PARP-2 catalytic mutant overexpression, co-immunoprecipitation of HDAC5/7 and G9a, ChIP at target gene promoters, reporter assays\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ChIP, catalytic mutant to separate enzymatic from non-enzymatic function, single lab\",\n      \"pmids\": [\"23291187\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PARP2 stabilizes replication forks that encounter BER intermediates through Fbh1-dependent regulation of Rad51. PARP2 is dispensable for tolerance to SSBs alone or for homologous recombination dysfunction, but is redundant with PARP1 in BER. Combined PARP1+PARP2 disruption causes defective BER, elevated replication-associated DNA damage, inability to stabilize Rad51 at damaged replication forks, and uncontrolled DNA resection.\",\n      \"method\": \"PARP1/PARP2 single and double knockouts, replication fork stability assays, Rad51 focus analysis, Fbh1 genetic epistasis, DNA resection assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic knockouts with epistasis analysis (Fbh1), multiple cellular phenotypic readouts, pathway placement\",\n      \"pmids\": [\"29467415\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PARP2 controls DSB repair pathway choice independently of its PAR synthesis activity by limiting accumulation of the resection barrier 53BP1 at DNA damage sites, thereby promoting CtIP-dependent DNA end-resection and channeling repair toward HR, SSA, and alternative end-joining rather than canonical NHEJ.\",\n      \"method\": \"PARP2 knockout and catalytic mutant cells, 53BP1 focus analysis, CtIP-dependent resection assay, HR/SSA/A-EJ/C-EJ reporter assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — catalytic mutant distinguishes enzymatic from structural function, multiple repair pathway reporters, defined molecular mechanism\",\n      \"pmids\": [\"29036662\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PARP2 is preferentially activated by PAR itself (not just DNA breaks), and this PAR-dependent activation leads PARP2 to preferentially catalyze branched PAR chain synthesis. The N-terminus of PARP2 directly binds PAR to promote enzymatic activity toward branched chain synthesis. The PBZ domain of APLF specifically recognizes branched PAR chains to regulate chromatin remodeling in the DNA damage response.\",\n      \"method\": \"In vitro PAR synthesis assay with pre-formed PAR as activator, N-terminus deletion/mutation, PAR structure analysis, APLF-PBZ pulldown with branched PAR\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution showing PAR-dependent activation, domain mutagenesis, and PAR structure characterization with downstream reader identification\",\n      \"pmids\": [\"30104678\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PARP2 and PARP3 can PARylate and MARylate (respectively) 5'- and 3'-terminal phosphate residues at double- and single-strand break termini of DNA molecules in vitro, demonstrating that PARPs can directly ADP-ribosylate DNA ends in addition to protein substrates.\",\n      \"method\": \"In vitro ADP-ribosylation assay with defined DNA substrates, PAR/MAR detection methods, cell-free extracts, anti-PAR antibody on purified genomic DNA from bleomycin-treated cells\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple in vitro reconstitution approaches with defined substrates, corroborated by cell-based detection\",\n      \"pmids\": [\"29361132\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PARP-2, but not PARP-1, is a critical component of the androgen receptor (AR) transcriptional machinery in prostate cancer cells through direct interaction with the pioneer factor FOXA1, facilitating AR recruitment to genome-wide prostate-specific enhancer regions. Selective PARP-2 targeting blocks PARP-2-FOXA1 interaction, attenuating AR-mediated gene expression and inhibiting PCa growth.\",\n      \"method\": \"Co-immunoprecipitation of PARP-2 with FOXA1, ChIP-seq for AR and PARP-2, siRNA/pharmacological PARP-2 knockdown, gene expression analysis, cell proliferation assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP with genome-wide ChIP-seq, loss-of-function with specific transcriptional and proliferation phenotypes, multiple orthogonal methods\",\n      \"pmids\": [\"31266892\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Cryo-EM structure of human PARP2-HPF1 bound to a nucleosome shows PARP2-HPF1 bridges two nucleosomes with broken DNA aligned for ligation. DNA break bridging induces conformational changes in PARP2 that signal DNA break recognition to the catalytic domain, licensing HPF1 binding and PARP2 activation. HPF1 switches PARP2 amino acid specificity from aspartate/glutamate to serine. Active PARP2 cycles through conformational states to exchange NAD+ and substrate.\",\n      \"method\": \"Cryo-electron microscopy structural determination of PARP2-HPF1-nucleosome complex\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — high-resolution cryo-EM structure with mechanistic interpretation of conformational activation, replicated by second cryo-EM study (PMID 33141820)\",\n      \"pmids\": [\"32939087\", \"33141820\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"The chromatin remodeler ALC1 (CHD1L) is strictly required for PARP2 release from DNA damage sites. Catalytic inactivation of ALC1 quantitatively traps PARP2 but not PARP1. PARP inhibitors robustly trap PARP2 at DNA lesions, impacting cellular DNA damage responses.\",\n      \"method\": \"Live-cell imaging of PARP2 foci, ALC1 catalytic mutant cell lines, PARP inhibitor treatment, PARP2 vs PARP1 differential analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — live-cell imaging with genetic manipulation, specific dissociation of PARP1 and PARP2 trapping, defined mechanistic role for ALC1\",\n      \"pmids\": [\"33275888\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PARP2 deficiency in myeloid cells increases immature myeloid cell populations in bone marrow and impairs CCL3 chemokine expression by enhancing transcriptional repression by β-catenin, creating an immune-suppressive microenvironment that promotes breast cancer bone metastasis.\",\n      \"method\": \"Myeloid-specific PARP2 knockout mice, osteoclast differentiation assays, bone marrow cell population analysis, β-catenin ChIP, CCL3 expression analysis, T cell population analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockout with ChIP mechanistic link, single lab, complex phenotype\",\n      \"pmids\": [\"32221289\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Crystal structure of PARP2 in complex with activating 5'-phosphorylated DNA shows the WGR domain bridges the dsDNA gap and joins DNA ends; DNA binding causes major conformational changes including reorganization of helical fragments in the regulatory domain, relieving autoinhibition. The activated conformation allows NAD+ binding and HPF1 association (which switches residue specificity from glutamate to serine).\",\n      \"method\": \"X-ray crystallography, comparison with PARP1 crystal structures, in vitro activity assays with HPF1\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with mechanistic validation of conformational changes and HPF1 interaction, corroborates cryo-EM findings\",\n      \"pmids\": [\"34108479\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HPF1 has a dual function with PARP2: it can both stimulate DNA-dependent and DNA-independent autoPARylation of PARP2 (and histone heteroPARylation) at defined HPF1/NAD+ concentrations, and suppress PARylation activity (promoting NAD+ hydrolysis) at higher concentrations. PARP2 is more efficiently stimulated by HPF1 in automodification and is more active in histone heteroPARylation than automodification.\",\n      \"method\": \"In vitro PARylation assays with purified PARP2, HPF1, and nucleosomes; NAD+ hydrolase assay; comparison with PARP1\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — reconstituted in vitro system with purified components, systematic concentration-dependence analysis, single lab\",\n      \"pmids\": [\"34732825\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PARP-1 and PARP-2 deficiency in the uterus leads to pregnancy loss due to decidualization failure. Absence of PARP-1 and PARP-2 increases p53 signaling and senescent decidual cells. Embryo attachment and luminal epithelium removal are unaffected; the defect is specifically at decidualization.\",\n      \"method\": \"Uterine-specific PARP-1/PARP-2 conditional knockout mice, histology, p53 signaling analysis, senescence markers, embryo attachment assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockout with specific phenotypic placement of defect, single lab\",\n      \"pmids\": [\"34580230\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PARP2 predominantly functions in single-strand break repair at actively transcribed DNA regions; this function is bypassed when transcription is inhibited. CSB chromatin remodeler recruits XRCC1 and HPF1 downstream of PARP1 and PARP2, and CSB regulates SSBR mediated by both PARP1 and PARP2.\",\n      \"method\": \"Chromatin co-fractionation, alkaline comet assay for SSBR kinetics, transcription inhibition experiments, PARP1/PARP2-deficient cells\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — fractionation studies with functional repair assay, single lab, transcription-dependence validated\",\n      \"pmids\": [\"37326017\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PARP inhibitors trap PARP2 by switching its recruitment mode from predominantly PARP1- and PAR-dependent rapid exchange to WGR domain-mediated stalling on DNA. In PARP1-deficient cells, residual PARP2 foci are DNA-dependent and require the WGR domain (R140 critical) and catalytic domain (H415). PARP2 trapping by inhibitors is independent of auto-PARylation.\",\n      \"method\": \"Live-cell imaging in PARP1-deficient cells, WGR (R140A) and catalytic (H415A) domain PARP2 mutants, PARP inhibitor treatment (niraparib, talazoparib, olaparib)\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — live-cell imaging with domain-specific mutants and genetic deletion, multiple inhibitors tested, mechanistic dissection of trapping mode\",\n      \"pmids\": [\"35349716\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Certain clinical PARP inhibitors exert an allosteric effect on PARP2 that increases its retention on DNA breaks through communication between the catalytic and DNA-binding regions; this is distinct from PARP1 where no clinical PARPi exhibits allosteric retention. AZD5305 exhibits a clear reverse allosteric effect on PARP2.\",\n      \"method\": \"Biochemical PARP2 DNA retention assay, PARP2 allosteric mutant mimicking inhibitor-bound state, live-cell imaging of PARP2 at damage sites\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — biochemical allosteric assay with confirmatory live-cell imaging and allosteric mutant, clearly distinguishes PARP1 from PARP2 mechanisms\",\n      \"pmids\": [\"36961901\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PARP2 forms a remarkably stable mechanical bridge (rupture force ~85 pN) across blunt-end 5'-phosphorylated DSBs and restores torsional continuity. PARP2 switches between bridging and end-binding modes depending on DNA overhang type. In contrast, PARP1 does not form bridging interactions across blunt or short overhang DSBs and competes away PARP2 bridge formation.\",\n      \"method\": \"Single-molecule magnetic tweezers force spectroscopy, defined DSB substrates with various overhangs\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — single-molecule biophysical reconstitution with quantitative force measurements and multiple substrate types\",\n      \"pmids\": [\"37216533\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"DNA replication specifically activates PARP2 robustly; PARP2 is selectively recruited and activated by 5'-phosphorylated nicks (5'p-nicks) between Okazaki fragments. Catalytically inactive PARP2 (E534A), but not absent PARP2, impedes Ligase 1- and Ligase 3-mediated ligation, causing dose-dependent replication fork collapse. This PARylation-dependent structural function at nicks is essential for erythropoiesis and explains PARPi-induced anemia.\",\n      \"method\": \"Parp2 E534A knock-in mice, comparison with Parp2-/- and Lig1-/- mice, Okazaki fragment ligation assay, replication fork analysis, Tp53/Chk2 genetic epistasis, selective PARP2 recruitment to 5'p-nicks\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — catalytic knock-in vs knockout genetic dissection, in vitro ligation assay, multiple epistasis backgrounds, mechanistic separation of enzymatic and structural functions\",\n      \"pmids\": [\"39383878\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PARP2 promotes replication stress-induced telomere fragility via the break-induced replication (BIR) pathway by orchestrating DNA end resection, strand invasion, and BIR-dependent mitotic DNA synthesis through POLD3 recruitment and activity.\",\n      \"method\": \"PARP2 knockout cells, BIR reporter assay, POLD3 recruitment analysis, telomere fragility assay (FISH), BLM helicase depletion model, oxidative lesion induction\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with mechanistic pathway readouts, single lab, multiple assays\",\n      \"pmids\": [\"38565848\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PARP2 is a DNA damage-activated ADP-ribosyltransferase that is selectively recruited and activated by 5'-phosphorylated DNA nicks and breaks via its WGR domain (which bridges DNA ends and undergoes allosteric conformational changes to relieve autoinhibition), catalyzes both linear and branched poly(ADP-ribose) synthesis on protein substrates (switching to serine specificity with HPF1) and directly on DNA termini, operates redundantly with PARP1 in base excision repair and SSB repair (while having specialized roles in replication fork stabilization via Rad51/Fbh1, DSB repair pathway choice via 53BP1 suppression, branched PAR synthesis, and POLD3-dependent break-induced replication at telomeres), and also acts as a transcriptional repressor of SIRT1 and SREBP1 promoters and interacts with multiple partners including TRF2, FOXA1/AR, TIF1β/HP1α, and BER scaffold proteins XRCC1/pol β/LigIII, with its activity regulated by acetylation at K36/K37 and by PARP inhibitors that allosterically trap it on DNA through WGR-mediated stalling.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PARP2 is a nuclear DNA damage-activated ADP-ribosyltransferase that catalyzes poly(ADP-ribose) synthesis in a DNA-dependent manner and undergoes automodification, accounting for the residual PAR synthesis in PARP1-deficient cells [#0]. It is selectively recruited and activated by DNA breaks bearing a 5'-phosphate, particularly single-strand nicks, with the WGR domain serving as the central regulatory module that bridges DNA ends and undergoes conformational changes relieving catalytic-domain autoinhibition [#17, #22, #23, #33]; the cofactor HPF1 binds the activated enzyme and switches its amino-acid specificity from aspartate/glutamate to serine [#30, #33]. Beyond protein modification, PARP2 is itself activated by PAR to preferentially build branched PAR chains read by APLF, and can directly ADP-ribosylate 5'- and 3'-terminal phosphates at DNA break termini [#27, #28]. Functionally PARP2 operates redundantly with PARP1 in base excision and single-strand break repair—interacting with the BER scaffold XRCC1, DNA polymerase β and DNA ligase III [#1, #25, #36]—while carrying specialized structural roles: it stabilizes replication forks via Fbh1-dependent Rad51 regulation [#25], controls DSB repair pathway choice independently of its catalytic activity by limiting 53BP1 to promote CtIP-dependent resection [#26], bridges DNA ends as a stable mechanical clamp [#39], and seals 5'-phosphorylated nicks between Okazaki fragments in a PARylation-dependent structural function essential for erythropoiesis [#40]. Genetic loss causes radiosensitivity, genomic and telomeric instability, and combined PARP1/PARP2 deletion is embryonic lethal, establishing overlapping essential functions [#2, #3]. PARP2 also acts as a transcriptional repressor of the SIRT1 and SREBP1 promoters, linking it to mitochondrial biogenesis, energy expenditure and lipid metabolism [#11, #16], and is a component of the FOXA1/androgen-receptor transcriptional machinery in prostate cancer [#29]. Clinical PARP inhibitors trap PARP2 on DNA by switching its recruitment to WGR-mediated stalling and, for certain inhibitors, through a reverse allosteric effect distinct from PARP1, with the chromatin remodeler ALC1 required for PARP2 release from damage sites [#31, #37, #38].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established that a second DNA-dependent PARP exists, explaining residual PAR synthesis in PARP1-null cells and defining PARP2 as a nuclear damaged-DNA-binding ADP-ribosyltransferase.\",\n      \"evidence\": \"Recombinant protein purification, in vitro DNA-binding and PAR synthesis assays, nuclear localization by fractionation/immunofluorescence\",\n      \"pmids\": [\"10364231\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"DNA substrate specificity not defined\", \"no domain dissection of activation mechanism\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Placed PARP2 physically and functionally in the base excision repair machinery and showed it dimerizes with PARP1, defining its repair partners and a loss-of-function repair phenotype.\",\n      \"evidence\": \"Reciprocal Co-IP and pulldown with XRCC1/pol β/LigIII, interaction interface mapping, PARP2-knockout mouse comet assay after MNU\",\n      \"pmids\": [\"11948190\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"redundancy with PARP1 not quantitatively separated\", \"no structural basis for substrate handoff\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Demonstrated PARP2 is required for genome stability and shares essential developmental functions with PARP1, since double knockout is lethal at gastrulation.\",\n      \"evidence\": \"Knockout mouse genetics, metaphase cytogenetics, irradiation survival, flow cytometry\",\n      \"pmids\": [\"12727891\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"molecular basis of kinetochore/segregation defect unresolved\", \"individual vs redundant contributions not separated\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Connected PARP2 to telomere protection through direct modification of TRF2, explaining telomeric instability in PARP2-null cells.\",\n      \"evidence\": \"Reciprocal Co-IP with domain mapping, ADP-ribosylation assays, telomere FISH in knockout cells\",\n      \"pmids\": [\"14749375\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"in vivo significance of TRF2 modification not established\", \"no structural detail of the interaction\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Localized PARP2 to the nucleolus via an N-terminal NLS/NoLS and constitutive B23 association, broadening its subnuclear distribution beyond damage sites.\",\n      \"evidence\": \"Immunofluorescence, Co-IP, NLS/NoLS mutagenesis, RNA pol I inhibition in PARP1/2-deficient MEFs\",\n      \"pmids\": [\"15615785\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"functional consequence of nucleolar localization unclear\", \"no link to a nucleolar substrate\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identified post-translational and heterochromatin-linked regulation of PARP2, showing acetylation at K36/K37 dampens its activity and that it modifies HP1α and partners with TIF1β during differentiation.\",\n      \"evidence\": \"In vitro acetyltransferase assays, K36A/K37A mutagenesis, DNA-binding/auto-ADP-ribosylation assays; Co-IP, in vitro modification and shRNA differentiation assays\",\n      \"pmids\": [\"18436469\", \"18676401\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"in vivo stoichiometry of acetylation unknown\", \"deacetylase that reverses K36/K37 not identified\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Defined non-repair physiological roles of PARP2 in immunoglobulin class-switch translocation suppression and in spermiogenesis chromatin condensation.\",\n      \"evidence\": \"Parp1/Parp2 knockout B cells with translocation assays; protein-interaction and ADP-ribosylation assays with TP2/HSPA2, EM on Parp2-/- testes\",\n      \"pmids\": [\"19364882\", \"19607827\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"mechanism of translocation suppression not molecular\", \"whether spermatid complex is direct or scaffolded unclear\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Provided the first crystallographic view of the PARP2 catalytic domain with inhibitors, enabling structure-guided selective inhibitor design.\",\n      \"evidence\": \"X-ray crystallography of catalytic domain with 3-AB and ABT-888\",\n      \"pmids\": [\"20092359\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"no DNA-bound or full-length structure\", \"allosteric activation not captured\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Revealed PARP2 as a transcriptional repressor of SIRT1, linking it to mitochondrial biogenesis, energy metabolism and β-cell function independent of NAD+ levels.\",\n      \"evidence\": \"Knockout mice, myotube siRNA, SIRT1 promoter ChIP and reporter assays, metabolic phenotyping\",\n      \"pmids\": [\"21459329\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"whether repression requires catalytic activity not resolved here\", \"co-repressor partners undefined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Extended PARP2's transcriptional and non-enzymatic regulatory repertoire to SREBP1 lipogenic control and to enzyme-independent chromatin repression via HDAC5/7 and G9a recruitment.\",\n      \"evidence\": \"Knockout mice and HepG2 siRNA with SREBP1 reporter/lipid analysis; catalytic-mutant overexpression, Co-IP and ChIP at cell-cycle gene promoters\",\n      \"pmids\": [\"24365238\", \"23291187\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"single-lab findings\", \"direct vs indirect promoter occupancy not fully distinguished\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Characterized PARP2's biochemical interactions with BER intermediates, showing it binds AP sites and inhibits APE1, pol β and FEN1 differently from PARP1, with distinct DNA-substrate preferences.\",\n      \"evidence\": \"EMSA, Schiff-base cross-linking, in vitro APE1/pol β/FEN1 activity and PAR synthesis assays\",\n      \"pmids\": [\"25724268\", \"23357680\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"no in vivo validation\", \"physiological relevance of enzyme inhibition unclear\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Established PARP inhibitor trapping of PARP1 and PARP2 on DNA as a cytotoxic mechanism distinct from catalytic inhibition, and mapped repair pathways that resolve trapped complexes.\",\n      \"evidence\": \"Cellular trapping and clonogenic assays across 30 genetically defined DT40 lines; in vitro TOP2B inhibition with purified PARPs plus genetic/pharmacological mouse spermatid assays\",\n      \"pmids\": [\"23118055\", \"21228215\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"PARP2-specific trapping mechanism not yet dissected\", \"structural basis of trapping unresolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined the activation logic and domain architecture of PARP2: activation by 5'-phosphorylated breaks, the WGR domain as central regulator, a shared allosteric destabilization mechanism, and RNA as an additional activator via the SAP domain.\",\n      \"evidence\": \"Biochemical activation assays with defined DNA/RNA substrates, domain deletion/mutagenesis, cellular knockdown with RNA-accumulating conditions\",\n      \"pmids\": [\"24928857\", \"24510188\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"structural detail of the WGR-DNA contact not yet solved\", \"physiological role of RNA activation unclear\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Tied PARP2 loss to replicative stress in erythropoiesis and to a miR-149/NAD+/SIRT1 metabolic axis, revealing tissue-level consequences of PARP2 deficiency.\",\n      \"evidence\": \"Knockout mice with γ-H2AX/CHK1/RPA assays and Puma/p21 epistasis; miR-149 overexpression and PARP2 knockdown in myotubes with NAD+/SIRT1/PGC-1α readouts\",\n      \"pmids\": [\"25501596\", \"24757201\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"molecular source of erythroblast replication stress not pinpointed here\", \"miR-149 axis is single-lab\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Resolved PARP2 substrate recognition at single-molecule and domain resolution, showing preferential recognition of single nicks, branched PAR output from SSBs, and collective contribution of NTR/WGR/CAT domains to damage engagement.\",\n      \"evidence\": \"SAXS/SEC-MALS, single-molecule AFM, fluorescence titration, live-cell laser micro-irradiation with domain-deletion mutants, PAR synthesis assays\",\n      \"pmids\": [\"26704974\", \"26673720\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"atomic-resolution DNA-bound structure still lacking\", \"functional role of branched PAR not yet defined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Provided crystallographic and structural definition of WGR-mediated DNA end recognition, showing PARP2 reads the 5'-phosphate and bridges DNA ends to drive catalytic activation.\",\n      \"evidence\": \"X-ray crystallography of WGR-DNA complex with WGR-interface mutagenesis and in vitro activity/binding assays\",\n      \"pmids\": [\"30321391\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"full-length conformational change not captured\", \"HPF1 not included\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Separated PARP2's catalytic from structural functions at the replication fork and at DSBs, defining Fbh1/Rad51-dependent fork stabilization and a non-enzymatic 53BP1-limiting role in repair pathway choice.\",\n      \"evidence\": \"PARP1/PARP2 single and double knockouts with fork stability, Rad51 focus, Fbh1 epistasis and resection assays; catalytic-mutant cells with 53BP1 foci and HR/SSA/A-EJ/C-EJ reporters\",\n      \"pmids\": [\"29467415\", \"29036662\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"how PARP2 mechanistically limits 53BP1 not defined\", \"direct vs indirect Fbh1 regulation unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Discovered PAR-induced activation of PARP2 driving branched-chain synthesis read by APLF, and direct ADP-ribosylation of DNA termini, expanding PARP2's catalytic outputs beyond protein modification.\",\n      \"evidence\": \"In vitro PAR synthesis with pre-formed PAR activator, N-terminus mutagenesis, PAR structure analysis, APLF-PBZ pulldown; in vitro DNA-end ADP-ribosylation with cell-based detection\",\n      \"pmids\": [\"30104678\", \"29361132\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"cellular abundance and turnover of DNA-ADP-ribosylation unknown\", \"branched PAR signaling outputs incompletely mapped\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified a PARP2-specific transcriptional role in prostate cancer, where it bridges FOXA1 to direct genome-wide androgen-receptor recruitment, distinguishing it functionally from PARP1.\",\n      \"evidence\": \"Co-IP with FOXA1, AR/PARP2 ChIP-seq, siRNA/pharmacological knockdown, expression and proliferation assays\",\n      \"pmids\": [\"31266892\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"whether catalytic activity is required not resolved\", \"structural basis of FOXA1 interaction unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Provided high-resolution structural mechanism of PARP2 activation on chromatin: DNA-break bridging drives conformational signaling that licenses HPF1 binding and switches modification specificity to serine.\",\n      \"evidence\": \"Cryo-EM of PARP2-HPF1-nucleosome complex (two independent structures); ALC1 catalytic-mutant live-cell imaging for PARP2 release\",\n      \"pmids\": [\"32939087\", \"33141820\", \"33275888\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"dynamics of NAD+/substrate cycling inferred not directly observed\", \"in vivo HPF1 occupancy not quantified\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Extended PARP2 function to the tumor immune microenvironment, where myeloid PARP2 loss enhances β-catenin repression of CCL3 to promote breast cancer bone metastasis.\",\n      \"evidence\": \"Myeloid-specific knockout mice, bone marrow population analysis, β-catenin ChIP and CCL3 expression\",\n      \"pmids\": [\"32221289\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"single-lab finding\", \"direct PARP2-β-catenin mechanism not biochemically defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Captured the DNA-induced activated conformation crystallographically and dissected HPF1's biphasic, concentration-dependent control over PARP2 PARylation versus NAD+ hydrolysis.\",\n      \"evidence\": \"X-ray crystallography of PARP2-5'p-DNA with PARP1 comparison; reconstituted in vitro PARylation and NAD+ hydrolase assays with PARP2/HPF1/nucleosomes\",\n      \"pmids\": [\"34108479\", \"34732825\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"cellular HPF1 concentrations relative to thresholds unknown\", \"physiological balance of activities undefined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Established that PARP2's single-strand break repair function is concentrated at actively transcribed loci and connected SSBR to the CSB chromatin remodeler and decidualization-linked pregnancy maintenance.\",\n      \"evidence\": \"Chromatin co-fractionation and comet assays with transcription inhibition; uterine-specific PARP1/PARP2 conditional knockout with p53/senescence analysis\",\n      \"pmids\": [\"37326017\", \"34580230\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"single-lab findings\", \"mechanistic basis of transcription coupling not fully defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Resolved the biophysical and pharmacological basis of PARP2 trapping, showing WGR-mediated stalling and inhibitor-driven mechanical bridging of DSBs, and a PARP2-specific reverse allosteric retention effect absent in PARP1.\",\n      \"evidence\": \"Live-cell imaging in PARP1-deficient cells with WGR (R140A)/catalytic (H415A) mutants; biochemical retention assays and allosteric mutants; single-molecule magnetic tweezers force spectroscopy\",\n      \"pmids\": [\"35349716\", \"36961901\", \"37216533\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"clinical relevance of allosteric retention to therapy response not established\", \"in vivo prevalence of bridging mode unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined PARP2's essential PARylation-dependent structural role in sealing Okazaki-fragment 5'p-nicks during replication and in driving POLD3-dependent break-induced replication at telomeres, mechanistically explaining PARPi-induced anemia.\",\n      \"evidence\": \"Parp2 E534A catalytic knock-in vs knockout mice, in vitro ligation assays, replication fork and Tp53/Chk2 epistasis; PARP2 knockout cells with BIR reporter, POLD3 recruitment and telomere fragility assays\",\n      \"pmids\": [\"39383878\", \"38565848\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"BIR pathway finding is single-lab\", \"how catalytically inactive PARP2 impedes ligation structurally not fully resolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How PARP2's diverse functions—transcriptional repression, branched PAR signaling, replication-nick sealing, and DSB bridging—are coordinated and selected within a cell, and which are most therapeutically exploitable, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"no unified model linking transcriptional and repair roles\", \"in vivo determinants of catalytic vs structural function selection unknown\", \"PARP2-selective inhibitor consequences across tissues incompletely mapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [0, 17, 27, 28]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 28, 30, 34]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0, 14, 17, 22, 23]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [18]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [11, 16, 24, 29]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [3, 6, 30]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"GO:0005730\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [3, 30]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [1, 25, 26, 36]},\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [25, 40, 41]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [11, 16, 24, 29]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [6, 24, 27]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [11, 16, 20]}\n    ],\n    \"complexes\": [\"PARP2-HPF1-nucleosome complex\", \"PARP1/PARP2/TP2/HSPA2 spermatid complex\"],\n    \"partners\": [\"PARP1\", \"XRCC1\", \"HPF1\", \"TRF2\", \"FOXA1\", \"HP1alpha\", \"TIF1beta\", \"FEN1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}