{"gene":"MACROD1","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":2007,"finding":"LRP16 (MACROD1) physically interacts with estrogen receptor alpha (ERα) via the A/B activation function 1 domain of ERα, enhancing ERα-mediated transcriptional activity. This interaction was demonstrated by GST pulldown and co-immunoprecipitation, and is estrogen-independent but enhanced by estrogen.","method":"GST pulldown, co-immunoprecipitation, mammalian two-hybrid assay, siRNA knockdown with reporter gene readout","journal":"Endocrine-related cancer","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP and GST pulldown with functional validation by siRNA knockdown and target gene expression","pmids":["17914104"],"is_preprint":false},{"year":2008,"finding":"LRP16 (MACROD1) binds to androgen receptor (AR) via its macro domain and amplifies AR transactivation in response to androgen, also acting as a coactivator for at least four other nuclear receptors. RNAi knockdown of LRP16 impairs AR function and attenuates androgen-stimulated proliferation of LNCaP cells.","method":"Co-immunoprecipitation, GST pulldown (macro domain binding), RNAi knockdown, luciferase reporter assay, proliferation assay","journal":"Endocrine-related cancer","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP with domain mapping and functional siRNA validation","pmids":["19022849"],"is_preprint":false},{"year":2003,"finding":"LRP16 promoter activity is induced by ERα and androgen receptor (AR), and overexpression of LRP16 promotes MCF-7 cell cycle progression into S phase, with elevated cyclin E levels.","method":"Luciferase promoter assay, flow cytometry, Western blot","journal":"Endocrine-related cancer","confidence":"Medium","confidence_rationale":"Tier 3 — functional overexpression with cell cycle readout, no direct biochemical interaction data","pmids":["12790785"],"is_preprint":false},{"year":2007,"finding":"LRP16 promotes invasive growth of Ishikawa endometrial cancer cells by repressing E-cadherin transcription in an ERα-dependent manner; chromatin immunoprecipitation revealed that LRP16 antagonizes ERα binding to the E-cadherin promoter.","method":"Transwell invasion assay, promoter-reporter assay, ChIP assay, ectopic expression and estrogen deprivation","journal":"Cell research","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP with functional invasion assay, single lab","pmids":["17893710"],"is_preprint":false},{"year":2007,"finding":"ERα and Sp1 cooperate at GC-rich sites in the LRP16 promoter to mediate estrogen-induced transcription; ChIP confirmed functional ERα/Sp1 interaction at the -213/-184 bp region.","method":"ChIP assay, gel mobility shift assay (EMSA), deletion/mutation promoter analysis, Sp1-siRNA","journal":"The Journal of steroid biochemistry and molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP and EMSA with mutagenesis, single lab","pmids":["18206366"],"is_preprint":false},{"year":2009,"finding":"Keratin 18 (K18) interacts with LRP16 and sequesters it in the cytoplasm, reducing nuclear LRP16 availability and thereby attenuating ERα-mediated transcription and estrogen-stimulated cell cycle progression in MCF-7 cells.","method":"Yeast two-hybrid, GST pulldown, Co-immunoprecipitation, fluorescence localization, immunoblotting of nuclear/cytoplasmic fractions, BrdU incorporation, siRNA knockdown","journal":"BMC cell biology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (Y2H, GST, Co-IP, fractionation, functional assay) in a single study","pmids":["20035625"],"is_preprint":false},{"year":2011,"finding":"LRP16 integrates into the NF-κB transcriptional complex by directly associating with the p65 subunit, and is required for formation/stabilization of the functional NF-κB/p300/CBP complex in the nucleus following TNF-α stimulation; knockdown does not affect NF-κB nuclear translocation but impairs its transactivation and sensitizes cells to TNF-α-induced apoptosis.","method":"GST pulldown, Co-immunoprecipitation, luciferase reporter assay, RNAi knockdown, Annexin V/flow cytometry, ChIP","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus functional epistasis (translocation vs. activation), multiple orthogonal methods","pmids":["21483817"],"is_preprint":false},{"year":2015,"finding":"LRP16 constitutively interacts with PARP1 and IKKγ, forming a preassembly complex that facilitates DSB-induced recruitment of PIASy to IKKγ, enabling the SUMOylation and phosphorylation of IKKγ required for NF-κB activation after DNA double-strand breaks. This is dependent on DSB sensors Ku70/Ku80.","method":"Co-immunoprecipitation, GST pulldown, proximity ligation assay, siRNA knockdown, NF-κB reporter assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 — multiple Co-IPs defining complex composition with functional epistasis showing pathway position","pmids":["25735744"],"is_preprint":false},{"year":2017,"finding":"LRP16 selectively interacts with and activates the double-stranded RNA-dependent kinase PKR, and acts as a scaffold to assist formation of a PKR-IKKβ ternary complex, prolonging PAR-dependent NF-κB transactivation after DNA damage and conferring chemoresistance. A small molecule, MRS2578, abrogates LRP16 binding to PKR and IKKβ.","method":"Co-immunoprecipitation, pulldown, kinase assays, RNAi, small-molecule inhibitor, xenograft model","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 — biochemical interaction mapping combined with in vivo xenograft validation and pharmacological inhibition","pmids":["28820388"],"is_preprint":false},{"year":2018,"finding":"MacroD1 (LRP16) is a mono-ADP-ribose hydrolase localized to mitochondria (endogenous protein), highly expressed in skeletal muscle. It can efficiently remove ADP-ribose from 5' and 3'-phosphorylated double-stranded DNA adducts in vitro.","method":"Subcellular fractionation, immunofluorescence, in vitro ADP-ribose hydrolase assay with phosphorylated dsDNA substrates, Western blot of tissue panels","journal":"Frontiers in microbiology","confidence":"High","confidence_rationale":"Tier 1–2 — direct biochemical activity assay plus fractionation establishing mitochondrial localization of endogenous protein","pmids":["29410655"],"is_preprint":false},{"year":2018,"finding":"LRP16 promotes inflammatory responses in adipocytes via activation of Rac1 and downstream ERK1/2 (MAPK) signaling in LPS-stimulated conditions; knockdown of LRP16 reduces Rac1 expression, ERK activation, and inflammatory cytokine expression.","method":"LC-MS proteomics, Western blot, RNAi, ERK inhibitor (PD98059), Rac1 knockdown","journal":"Cellular physiology and biochemistry","confidence":"Medium","confidence_rationale":"Tier 3 — pathway placement via inhibitor and RNAi with proteomic screen, no direct binding demonstrated","pmids":["30562745"],"is_preprint":false},{"year":2020,"finding":"Crystal structure of MacroD1 in complex with ADP-ribose reveals that the β5-α10 switch loop mediates substrate recognition, conserved Phe272 orients the distal ribose of ADPR, and a hydrogen-bond network positions the catalytic water for hydrolysis. MacroD1 is recruited to DNA damage sites via recognition of ADP-ribosylation, and its hydrolase activity is essential for DNA damage repair.","method":"X-ray crystallography (structure of MacroD1-ADPR complex), site-directed mutagenesis of catalytic residues, in vitro hydrolase assay, live-cell imaging of DNA damage recruitment","journal":"DNA repair","confidence":"High","confidence_rationale":"Tier 1 — crystal structure plus mutagenesis plus in vitro activity assay plus cellular localization with functional consequence","pmids":["32683309"],"is_preprint":false},{"year":2020,"finding":"MACROD1 localizes predominantly to mitochondria of skeletal muscle (confirmed with monoclonal antibodies against endogenous protein), and loss of MACROD1 disrupts mitochondrial morphology. BioID interactome mapping showed that MACROD1 interactors are enriched for mitochondrial proteins and suggest a role in mitochondrial RNA metabolism.","method":"Monoclonal antibody immunofluorescence/fractionation, MACROD1 knockout cells, BioID proximity labeling, gene ontology analysis","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 — endogenous protein localization with validated antibodies, KO morphological phenotype, and BioID interactome","pmids":["32427867"],"is_preprint":false},{"year":2021,"finding":"Knockout of Macrod1 in mice results in a female-specific motor-coordination defect, consistent with its mitochondrial function in tissues relevant to motor control.","method":"Macrod1 gene knockout mouse model, standardized behavioral testing battery","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO with defined behavioral/motor phenotype, but molecular mechanism not directly dissected","pmids":["33578760"],"is_preprint":false},{"year":2024,"finding":"Macrod1 suppresses diabetic cardiomyopathy by inhibiting PARP1 expression, thereby reducing NAD+ consumption and activating SIRT3-mediated antioxidative stress signaling (PARP1-NAD+-SIRT3 axis). Cardiac-specific overexpression of Macrod1 partially reversed mitochondrial dysfunction and oxidative stress in a DCM mouse model.","method":"Macrod1 KO and cardiac-specific overexpression mouse models, STZ/HFD diabetic cardiomyopathy model, Western blot, NAD+ measurement, SIRT3 activity assay, primary cardiomyocyte experiments","journal":"Acta pharmacologica Sinica","confidence":"Medium","confidence_rationale":"Tier 2 — KO and OE mouse models with pathway-level mechanistic readouts, single lab","pmids":["38459256"],"is_preprint":false},{"year":2013,"finding":"LRP16 acts as a negative regulator of insulin action and adipogenesis in 3T3-L1 adipocytes by activating the mTOR signaling pathway, which promotes TNF-α secretion and suppresses IRS-1/PI3K/Akt phosphorylation and PPARγ expression; rapamycin treatment rescued these effects.","method":"Overexpression and siRNA knockdown in 3T3-L1 cells, glucose uptake assay, Western blot of signaling proteins, rapamycin inhibitor rescue","journal":"Hormone and metabolic research","confidence":"Medium","confidence_rationale":"Tier 3 — pathway placement via pharmacological rescue, no direct biochemical binding to mTOR complex","pmids":["23389992"],"is_preprint":false}],"current_model":"MACROD1 (LRP16) is a mitochondria-localized mono-ADP-ribose hydrolase whose macrodomain catalyzes removal of ADP-ribose from modified proteins and DNA ends (with Phe272 and a conserved hydrogen-bond network critical for catalysis); it also functions as a nuclear coactivator of ERα, AR, and NF-κB by forming direct complexes with these factors, and operates as a scaffold assembling PARP1-IKKγ and PKR-IKKβ complexes to amplify DNA-damage-induced NF-κB signaling, while cytoplasmic sequestration by keratin 18 limits its nuclear availability and its mitochondrial function controls NAD+ homeostasis through restraint of PARP1 to activate SIRT3-mediated antioxidant responses."},"narrative":{"teleology":[{"year":2003,"claim":"Initial characterization established that MACROD1 (LRP16) is an estrogen- and androgen-responsive gene whose overexpression drives cell cycle progression, raising the question of how it contributes to hormone-dependent proliferation.","evidence":"LRP16 promoter assays and flow cytometry in MCF-7 cells showing S-phase entry and cyclin E upregulation","pmids":["12790785"],"confidence":"Medium","gaps":["No direct interaction with hormone receptors demonstrated","Mechanism linking LRP16 to cyclin E induction unknown"]},{"year":2007,"claim":"The molecular basis of LRP16's role in estrogen signaling was resolved: it physically binds the ERα AF-1 domain and coactivates ERα-dependent transcription, establishing it as a bona fide nuclear receptor coactivator.","evidence":"GST pulldown, co-immunoprecipitation, mammalian two-hybrid, and siRNA knockdown with reporter readout","pmids":["17914104","17893710","18206366"],"confidence":"High","gaps":["Whether coactivation requires enzymatic activity was unknown","Structural basis of ERα–LRP16 interaction not determined"]},{"year":2008,"claim":"The coactivator function was generalized beyond ERα: LRP16's macrodomain directly binds androgen receptor and at least four additional nuclear receptors, and RNAi demonstrated functional dependence of AR-driven proliferation on LRP16.","evidence":"Co-IP and GST pulldown mapping the macro domain as the AR-interacting region, luciferase reporter and proliferation assays in LNCaP cells","pmids":["19022849"],"confidence":"High","gaps":["Whether macrodomain enzymatic activity is required for coactivation remained untested","In vivo relevance not established"]},{"year":2009,"claim":"A regulatory mechanism controlling MACROD1 nuclear availability was identified: keratin 18 sequesters it in the cytoplasm, attenuating ERα-mediated transcription and estrogen-driven cell cycle progression.","evidence":"Yeast two-hybrid, GST pulldown, co-IP, nuclear/cytoplasmic fractionation, and BrdU incorporation in MCF-7 cells","pmids":["20035625"],"confidence":"High","gaps":["Whether K18 interaction is regulated by post-translational modification unknown","Physiological contexts where K18 sequestration is rate-limiting not defined"]},{"year":2011,"claim":"MACROD1 was placed in the NF-κB pathway: it associates with p65, is required for formation of the NF-κB/p300/CBP transactivation complex after TNF-α stimulation, and its loss sensitizes cells to TNF-α-induced apoptosis — distinguishing a role in transactivation from nuclear translocation.","evidence":"GST pulldown, co-IP, luciferase reporter, ChIP, and Annexin V apoptosis assay","pmids":["21483817"],"confidence":"High","gaps":["Whether NF-κB coactivation and steroid receptor coactivation are mutually exclusive or concurrent was unclear","No structural detail of p65–LRP16 interface"]},{"year":2015,"claim":"The scaffold function of MACROD1 in DNA damage-induced NF-κB signaling was defined: it constitutively assembles a PARP1–IKKγ preassembly complex that recruits PIASy for IKKγ SUMOylation after DSBs, in a Ku70/Ku80-dependent manner.","evidence":"Co-IP, GST pulldown, proximity ligation assay, siRNA epistasis, and NF-κB reporter in response to etoposide-induced DSBs","pmids":["25735744"],"confidence":"High","gaps":["Whether MACROD1's hydrolase activity contributes to complex assembly not tested","Stoichiometry and dynamics of the preassembly complex unknown"]},{"year":2017,"claim":"A second scaffold axis was discovered: MACROD1 activates PKR and nucleates a PKR–IKKβ ternary complex that sustains PAR-dependent NF-κB signaling after DNA damage, conferring chemoresistance that can be reversed by the small molecule MRS2578.","evidence":"Co-IP, kinase assays, RNAi, MRS2578 pharmacological disruption, and xenograft tumor model","pmids":["28820388"],"confidence":"High","gaps":["Binding mode of MRS2578 to MACROD1 not structurally resolved","Whether PKR scaffold function operates outside DNA damage contexts unknown"]},{"year":2018,"claim":"The intrinsic enzymatic activity of MACROD1 was biochemically characterized: it is a mono-ADP-ribose hydrolase that removes ADP-ribose from phosphorylated DNA ends, and the endogenous protein localizes predominantly to mitochondria.","evidence":"Subcellular fractionation and immunofluorescence of endogenous protein, in vitro hydrolase assay with phosphorylated dsDNA substrates","pmids":["29410655"],"confidence":"High","gaps":["In vivo mitochondrial substrates not identified","Relationship between mitochondrial localization and nuclear coactivator functions unresolved"]},{"year":2020,"claim":"The structural mechanism of catalysis was determined at atomic resolution: the β5-α10 switch loop mediates substrate recognition, Phe272 orients the distal ribose, and the hydrolase activity is essential for recruitment to and repair of DNA damage sites.","evidence":"X-ray crystallography of MacroD1–ADPR complex, site-directed mutagenesis, in vitro hydrolase assay, live-cell imaging of DNA damage recruitment","pmids":["32683309"],"confidence":"High","gaps":["Whether catalytic-dead mutant retains scaffold/coactivator functions not tested","No structure of full-length MACROD1 or in complex with protein substrates"]},{"year":2020,"claim":"Mitochondrial function was validated with knockout cells: loss of MACROD1 disrupts mitochondrial morphology, and BioID proximity labeling revealed an interactome enriched for mitochondrial RNA metabolism factors.","evidence":"Monoclonal antibody localization, MACROD1 knockout cells, BioID interactome profiling","pmids":["32427867"],"confidence":"High","gaps":["Specific mitochondrial RNA substrates not identified","Whether morphology defect is due to loss of hydrolase activity or protein interactions not dissected"]},{"year":2021,"claim":"In vivo loss of Macrod1 produces a female-specific motor coordination defect in mice, linking its mitochondrial function to neuromuscular physiology.","evidence":"Macrod1 knockout mouse model with standardized behavioral testing","pmids":["33578760"],"confidence":"Medium","gaps":["Molecular mechanism underlying female specificity not determined","Tissue-specific basis (skeletal muscle vs. brain) not resolved"]},{"year":2024,"claim":"A cardioprotective axis was delineated: MACROD1 suppresses PARP1, preserving NAD⁺ pools and activating SIRT3-dependent antioxidant signaling, and cardiac-specific overexpression rescues diabetic cardiomyopathy in mice.","evidence":"Macrod1 KO and cardiac-specific overexpression in STZ/HFD diabetic cardiomyopathy mouse model, NAD⁺ measurement, SIRT3 activity assay","pmids":["38459256"],"confidence":"Medium","gaps":["Whether MACROD1 directly modifies PARP1 ADP-ribosylation or acts indirectly to suppress PARP1 expression not resolved","Single-lab finding awaiting independent replication"]},{"year":null,"claim":"The central unresolved question is how MACROD1's enzymatic hydrolase activity, its scaffold/coactivator functions, and its dual mitochondrial–nuclear localization are coordinated in vivo, and what controls the balance between these compartments.","evidence":"","pmids":[],"confidence":"High","gaps":["No in vivo catalytic-dead knock-in to separate enzymatic from scaffold roles","Mitochondrial targeting signal and regulated nuclear import mechanism not fully defined","Identity of endogenous mitochondrial ADP-ribosylated substrates unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[9,11]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,1,6]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[7,8]},{"term_id":"GO:0140097","term_label":"catalytic activity, acting on DNA","supporting_discovery_ids":[9,11]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[9,12]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1,6,7,11]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[11]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[6,7,8]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,6,7,8,10]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,1,6]}],"complexes":["PARP1-IKKγ-MACROD1 preassembly complex","PKR-IKKβ-MACROD1 ternary complex"],"partners":["ESR1","AR","RELA","PARP1","IKBKG","EIF2AK2","KRT18","IKBKB"],"other_free_text":[]},"mechanistic_narrative":"MACROD1 (also known as LRP16) is a macrodomain-containing mono-ADP-ribose hydrolase that operates in both mitochondria and the nucleus to regulate ADP-ribosylation signaling, DNA damage repair, steroid receptor transcription, and NF-κB activation. Its macrodomain catalyzes hydrolytic removal of ADP-ribose from modified proteins and DNA ends, with crystal structures revealing that Phe272 and a conserved hydrogen-bond network orient the catalytic water for substrate cleavage, and this enzymatic activity is required for recruitment to and repair of DNA damage sites [PMID:32683309, PMID:29410655]. In the nucleus, MACROD1 functions as a transcriptional coactivator by directly binding ERα, AR, and the NF-κB p65 subunit, and as a scaffold assembling PARP1–IKKγ and PKR–IKKβ signaling complexes that amplify DNA-damage-induced NF-κB activation and confer chemoresistance [PMID:17914104, PMID:19022849, PMID:21483817, PMID:25735744, PMID:28820388]. In mitochondria, where the endogenous protein predominantly localizes, MACROD1 maintains organelle morphology and NAD⁺ homeostasis by restraining PARP1, thereby activating SIRT3-mediated antioxidant responses and protecting against diabetic cardiomyopathy [PMID:32427867, PMID:38459256]."},"prefetch_data":{"uniprot":{"accession":"Q9BQ69","full_name":"ADP-ribose glycohydrolase MACROD1","aliases":["MACRO domain-containing protein 1","O-acetyl-ADP-ribose deacetylase MACROD1","Protein LRP16","[Protein ADP-ribosylaspartate] hydrolase MACROD1","[Protein ADP-ribosylglutamate] hydrolase MACROD1"],"length_aa":325,"mass_kda":35.5,"function":"Removes ADP-ribose from aspartate and glutamate residues in proteins bearing a single ADP-ribose moiety (PubMed:23474712, PubMed:23474714). Inactive towards proteins bearing poly-ADP-ribose (PubMed:23474712, PubMed:23474714). Deacetylates O-acetyl-ADP ribose, a signaling molecule generated by the deacetylation of acetylated lysine residues in histones and other proteins (PubMed:21257746). Plays a role in estrogen signaling (PubMed:17893710, PubMed:17914104, PubMed:19403568). Binds to androgen receptor (AR) and amplifies the transactivation function of AR in response to androgen (PubMed:19022849). May play an important role in carcinogenesis and/or progression of hormone-dependent cancers by feed-forward mechanism that activates ESR1 transactivation (PubMed:17893710, PubMed:17914104). Could be an ESR1 coactivator, providing a positive feedback regulatory loop for ESR1 signal transduction (PubMed:17914104). Could be involved in invasive growth by down-regulating CDH1 in endometrial cancer cells (PubMed:17893710). Enhances ESR1-mediated transcription activity (PubMed:17914104)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9BQ69/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MACROD1","classification":"Not Classified","n_dependent_lines":9,"n_total_lines":1208,"dependency_fraction":0.0074503311258278145},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MACROD1","total_profiled":1310},"omim":[{"mim_id":"614393","title":"O-ACYL-ADP-RIBOSE DEACYLASE 1; OARD1","url":"https://www.omim.org/entry/614393"},{"mim_id":"610400","title":"MONO-ADP RIBOSYLHYDROLASE 1; MACROD1","url":"https://www.omim.org/entry/610400"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"skeletal muscle","ntpm":270.3}],"url":"https://www.proteinatlas.org/search/MACROD1"},"hgnc":{"alias_symbol":["LRP16"],"prev_symbol":[]},"alphafold":{"accession":"Q9BQ69","domains":[{"cath_id":"3.40.220.10","chopping":"106-322","consensus_level":"high","plddt":96.37,"start":106,"end":322}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BQ69","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BQ69-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BQ69-F1-predicted_aligned_error_v6.png","plddt_mean":82.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MACROD1","jax_strain_url":"https://www.jax.org/strain/search?query=MACROD1"},"sequence":{"accession":"Q9BQ69","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BQ69.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BQ69/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BQ69"}},"corpus_meta":[{"pmid":"19022849","id":"PMC_19022849","title":"The single-macro domain protein LRP16 is an essential cofactor of androgen receptor.","date":"2008","source":"Endocrine-related cancer","url":"https://pubmed.ncbi.nlm.nih.gov/19022849","citation_count":51,"is_preprint":false},{"pmid":"29410655","id":"PMC_29410655","title":"MacroD1 Is a Promiscuous ADP-Ribosyl Hydrolase Localized to Mitochondria.","date":"2018","source":"Frontiers in microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/29410655","citation_count":48,"is_preprint":false},{"pmid":"17914104","id":"PMC_17914104","title":"Estrogenically regulated LRP16 interacts with estrogen receptor alpha and enhances the receptor's transcriptional activity.","date":"2007","source":"Endocrine-related cancer","url":"https://pubmed.ncbi.nlm.nih.gov/17914104","citation_count":46,"is_preprint":false},{"pmid":"21483817","id":"PMC_21483817","title":"LRP16 integrates into NF-κB transcriptional complex and is required for its functional activation.","date":"2011","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/21483817","citation_count":34,"is_preprint":false},{"pmid":"32427867","id":"PMC_32427867","title":"Comparative analysis of MACROD1, MACROD2 and TARG1 expression, localisation and interactome.","date":"2020","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/32427867","citation_count":34,"is_preprint":false},{"pmid":"12790785","id":"PMC_12790785","title":"Up-regulation of LRP16 mRNA by 17beta-estradiol through activation of estrogen receptor alpha (ERalpha), but not ERbeta, and promotion of human breast cancer MCF-7 cell proliferation: a preliminary report.","date":"2003","source":"Endocrine-related cancer","url":"https://pubmed.ncbi.nlm.nih.gov/12790785","citation_count":34,"is_preprint":false},{"pmid":"17893710","id":"PMC_17893710","title":"Induction of the LRP16 gene by estrogen promotes the invasive growth of Ishikawa human endometrial cancer cells through the downregulation of E-cadherin.","date":"2007","source":"Cell research","url":"https://pubmed.ncbi.nlm.nih.gov/17893710","citation_count":28,"is_preprint":false},{"pmid":"32151005","id":"PMC_32151005","title":"The Controversial Roles of ADP-Ribosyl Hydrolases MACROD1, MACROD2 and TARG1 in Carcinogenesis.","date":"2020","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/32151005","citation_count":23,"is_preprint":false},{"pmid":"19824120","id":"PMC_19824120","title":"Clinicopathological significance of LRP16 protein in 336 gastric carcinoma patients.","date":"2009","source":"World journal of gastroenterology","url":"https://pubmed.ncbi.nlm.nih.gov/19824120","citation_count":21,"is_preprint":false},{"pmid":"28820388","id":"PMC_28820388","title":"Blockade of the LRP16-PKR-NF-κB signaling axis sensitizes colorectal carcinoma cells to DNA-damaging cytotoxic therapy.","date":"2017","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/28820388","citation_count":21,"is_preprint":false},{"pmid":"17532767","id":"PMC_17532767","title":"LRP16 is fused to RUNX1 in monocytic leukemia cell line with t(11;21)(q13;q22).","date":"2007","source":"European journal of haematology","url":"https://pubmed.ncbi.nlm.nih.gov/17532767","citation_count":19,"is_preprint":false},{"pmid":"25735744","id":"PMC_25735744","title":"An LRP16-containing preassembly complex contributes to NF-κB activation induced by DNA double-strand breaks.","date":"2015","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/25735744","citation_count":18,"is_preprint":false},{"pmid":"20035625","id":"PMC_20035625","title":"Keratin 18 attenuates estrogen receptor alpha-mediated signaling by sequestering LRP16 in cytoplasm.","date":"2009","source":"BMC cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/20035625","citation_count":17,"is_preprint":false},{"pmid":"38459256","id":"PMC_38459256","title":"Macrod1 suppresses diabetic cardiomyopathy via regulating PARP1-NAD+-SIRT3 pathway.","date":"2024","source":"Acta pharmacologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/38459256","citation_count":16,"is_preprint":false},{"pmid":"32683309","id":"PMC_32683309","title":"Molecular basis for the MacroD1-mediated hydrolysis of ADP-ribosylation.","date":"2020","source":"DNA repair","url":"https://pubmed.ncbi.nlm.nih.gov/32683309","citation_count":16,"is_preprint":false},{"pmid":"33578760","id":"PMC_33578760","title":"Behavioural Characterisation of Macrod1 and Macrod2 Knockout Mice.","date":"2021","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/33578760","citation_count":13,"is_preprint":false},{"pmid":"19403568","id":"PMC_19403568","title":"Differential induction of LRP16 by liganded and unliganded estrogen receptor alpha in SKOV3 ovarian carcinoma cells.","date":"2009","source":"The Journal of endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/19403568","citation_count":13,"is_preprint":false},{"pmid":"30562745","id":"PMC_30562745","title":"MACROD1/LRP16 Enhances LPS-Stimulated Inflammatory Responses by Up-Regulating a Rac1-Dependent Pathway in Adipocytes.","date":"2018","source":"Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/30562745","citation_count":12,"is_preprint":false},{"pmid":"18206366","id":"PMC_18206366","title":"GC-rich promoter elements maximally confers estrogen-induced transactivation of LRP16 gene through ERalpha/Sp1 interaction in MCF-7 cells.","date":"2007","source":"The Journal of steroid biochemistry and molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/18206366","citation_count":12,"is_preprint":false},{"pmid":"16831279","id":"PMC_16831279","title":"[Expression and clinical significance of LRP16 gene in human breast cancer].","date":"2006","source":"Ai zheng = Aizheng = Chinese journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/16831279","citation_count":11,"is_preprint":false},{"pmid":"23389992","id":"PMC_23389992","title":"Identification of LRP16 as a negative regulator of insulin action and adipogenesis in 3T3-L1 adipocytes.","date":"2013","source":"Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme","url":"https://pubmed.ncbi.nlm.nih.gov/23389992","citation_count":8,"is_preprint":false},{"pmid":"22800886","id":"PMC_22800886","title":"LRP16 gene protects mouse insulinoma MIN6 cells against fatty acid-induced apoptosis through Akt/FoxO1 signaling.","date":"2012","source":"Chinese medical journal","url":"https://pubmed.ncbi.nlm.nih.gov/22800886","citation_count":6,"is_preprint":false},{"pmid":"29551900","id":"PMC_29551900","title":"Leukemia-related protein 16 (LRP16) promotes tumor growth and metastasis in pancreatic cancer.","date":"2018","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/29551900","citation_count":4,"is_preprint":false},{"pmid":"12578638","id":"PMC_12578638","title":"[The Application of RACE Technique to Clone the Full-Length cDNA of A Novel Leukemia Associated Gene LRP16].","date":"2001","source":"Zhongguo shi yan xue ye xue za zhi","url":"https://pubmed.ncbi.nlm.nih.gov/12578638","citation_count":4,"is_preprint":false},{"pmid":"29748698","id":"PMC_29748698","title":"LRP16 prevents hepatocellular carcinoma progression through regulation of Wnt/β-catenin signaling.","date":"2018","source":"Journal of molecular medicine (Berlin, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/29748698","citation_count":4,"is_preprint":false},{"pmid":"16584612","id":"PMC_16584612","title":"[Analysis of LRP16 gene promoter activity].","date":"2006","source":"Zhongguo shi yan xue ye xue za zhi","url":"https://pubmed.ncbi.nlm.nih.gov/16584612","citation_count":3,"is_preprint":false},{"pmid":"22528219","id":"PMC_22528219","title":"Reduced expression of the LRP16 gene in mouse insulinoma (MIN6) cells exerts multiple effects on insulin content, proliferation and apoptosis.","date":"2012","source":"Journal of Huazhong University of Science and Technology. Medical sciences = Hua zhong ke ji da xue xue bao. Yi xue Ying De wen ban = Huazhong keji daxue xuebao. Yixue Yingdewen ban","url":"https://pubmed.ncbi.nlm.nih.gov/22528219","citation_count":2,"is_preprint":false},{"pmid":"21756814","id":"PMC_21756814","title":"[LRP16 gene causes insulin resistance in C2-C12 cells by inhibiting the IRS-1 signaling and the transcriptional activity of peroxisome proliferator actived receptor γ].","date":"2011","source":"Zhonghua yi xue za zhi","url":"https://pubmed.ncbi.nlm.nih.gov/21756814","citation_count":2,"is_preprint":false},{"pmid":"19840441","id":"PMC_19840441","title":"[Promotive effect of LRP16 gene on proliferation of K562 cells].","date":"2009","source":"Zhongguo shi yan xue ye xue za zhi","url":"https://pubmed.ncbi.nlm.nih.gov/19840441","citation_count":0,"is_preprint":false},{"pmid":"40525343","id":"PMC_40525343","title":"[Prokaryotic expression of mouse LRP16, preparation and identification of rabbit anti-mouse LRP16 polyclonal antibody].","date":"2025","source":"Xi bao yu fen zi mian yi xue za zhi = Chinese journal of cellular and molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/40525343","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.11.04.686626","title":"Mitochondrial bioenergetic signatures differentiate asymptomatic from symptomatic Alzheimer’s disease","date":"2025-11-06","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.04.686626","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":17645,"output_tokens":3669,"usd":0.053985},"stage2":{"model":"claude-opus-4-6","input_tokens":7213,"output_tokens":3216,"usd":0.174698},"total_usd":0.228683,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"LRP16 (MACROD1) physically interacts with estrogen receptor alpha (ERα) via the A/B activation function 1 domain of ERα, enhancing ERα-mediated transcriptional activity. This interaction was demonstrated by GST pulldown and co-immunoprecipitation, and is estrogen-independent but enhanced by estrogen.\",\n      \"method\": \"GST pulldown, co-immunoprecipitation, mammalian two-hybrid assay, siRNA knockdown with reporter gene readout\",\n      \"journal\": \"Endocrine-related cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP and GST pulldown with functional validation by siRNA knockdown and target gene expression\",\n      \"pmids\": [\"17914104\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"LRP16 (MACROD1) binds to androgen receptor (AR) via its macro domain and amplifies AR transactivation in response to androgen, also acting as a coactivator for at least four other nuclear receptors. RNAi knockdown of LRP16 impairs AR function and attenuates androgen-stimulated proliferation of LNCaP cells.\",\n      \"method\": \"Co-immunoprecipitation, GST pulldown (macro domain binding), RNAi knockdown, luciferase reporter assay, proliferation assay\",\n      \"journal\": \"Endocrine-related cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP with domain mapping and functional siRNA validation\",\n      \"pmids\": [\"19022849\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"LRP16 promoter activity is induced by ERα and androgen receptor (AR), and overexpression of LRP16 promotes MCF-7 cell cycle progression into S phase, with elevated cyclin E levels.\",\n      \"method\": \"Luciferase promoter assay, flow cytometry, Western blot\",\n      \"journal\": \"Endocrine-related cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — functional overexpression with cell cycle readout, no direct biochemical interaction data\",\n      \"pmids\": [\"12790785\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"LRP16 promotes invasive growth of Ishikawa endometrial cancer cells by repressing E-cadherin transcription in an ERα-dependent manner; chromatin immunoprecipitation revealed that LRP16 antagonizes ERα binding to the E-cadherin promoter.\",\n      \"method\": \"Transwell invasion assay, promoter-reporter assay, ChIP assay, ectopic expression and estrogen deprivation\",\n      \"journal\": \"Cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP with functional invasion assay, single lab\",\n      \"pmids\": [\"17893710\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"ERα and Sp1 cooperate at GC-rich sites in the LRP16 promoter to mediate estrogen-induced transcription; ChIP confirmed functional ERα/Sp1 interaction at the -213/-184 bp region.\",\n      \"method\": \"ChIP assay, gel mobility shift assay (EMSA), deletion/mutation promoter analysis, Sp1-siRNA\",\n      \"journal\": \"The Journal of steroid biochemistry and molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP and EMSA with mutagenesis, single lab\",\n      \"pmids\": [\"18206366\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Keratin 18 (K18) interacts with LRP16 and sequesters it in the cytoplasm, reducing nuclear LRP16 availability and thereby attenuating ERα-mediated transcription and estrogen-stimulated cell cycle progression in MCF-7 cells.\",\n      \"method\": \"Yeast two-hybrid, GST pulldown, Co-immunoprecipitation, fluorescence localization, immunoblotting of nuclear/cytoplasmic fractions, BrdU incorporation, siRNA knockdown\",\n      \"journal\": \"BMC cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (Y2H, GST, Co-IP, fractionation, functional assay) in a single study\",\n      \"pmids\": [\"20035625\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"LRP16 integrates into the NF-κB transcriptional complex by directly associating with the p65 subunit, and is required for formation/stabilization of the functional NF-κB/p300/CBP complex in the nucleus following TNF-α stimulation; knockdown does not affect NF-κB nuclear translocation but impairs its transactivation and sensitizes cells to TNF-α-induced apoptosis.\",\n      \"method\": \"GST pulldown, Co-immunoprecipitation, luciferase reporter assay, RNAi knockdown, Annexin V/flow cytometry, ChIP\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus functional epistasis (translocation vs. activation), multiple orthogonal methods\",\n      \"pmids\": [\"21483817\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"LRP16 constitutively interacts with PARP1 and IKKγ, forming a preassembly complex that facilitates DSB-induced recruitment of PIASy to IKKγ, enabling the SUMOylation and phosphorylation of IKKγ required for NF-κB activation after DNA double-strand breaks. This is dependent on DSB sensors Ku70/Ku80.\",\n      \"method\": \"Co-immunoprecipitation, GST pulldown, proximity ligation assay, siRNA knockdown, NF-κB reporter assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple Co-IPs defining complex composition with functional epistasis showing pathway position\",\n      \"pmids\": [\"25735744\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"LRP16 selectively interacts with and activates the double-stranded RNA-dependent kinase PKR, and acts as a scaffold to assist formation of a PKR-IKKβ ternary complex, prolonging PAR-dependent NF-κB transactivation after DNA damage and conferring chemoresistance. A small molecule, MRS2578, abrogates LRP16 binding to PKR and IKKβ.\",\n      \"method\": \"Co-immunoprecipitation, pulldown, kinase assays, RNAi, small-molecule inhibitor, xenograft model\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — biochemical interaction mapping combined with in vivo xenograft validation and pharmacological inhibition\",\n      \"pmids\": [\"28820388\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MacroD1 (LRP16) is a mono-ADP-ribose hydrolase localized to mitochondria (endogenous protein), highly expressed in skeletal muscle. It can efficiently remove ADP-ribose from 5' and 3'-phosphorylated double-stranded DNA adducts in vitro.\",\n      \"method\": \"Subcellular fractionation, immunofluorescence, in vitro ADP-ribose hydrolase assay with phosphorylated dsDNA substrates, Western blot of tissue panels\",\n      \"journal\": \"Frontiers in microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct biochemical activity assay plus fractionation establishing mitochondrial localization of endogenous protein\",\n      \"pmids\": [\"29410655\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"LRP16 promotes inflammatory responses in adipocytes via activation of Rac1 and downstream ERK1/2 (MAPK) signaling in LPS-stimulated conditions; knockdown of LRP16 reduces Rac1 expression, ERK activation, and inflammatory cytokine expression.\",\n      \"method\": \"LC-MS proteomics, Western blot, RNAi, ERK inhibitor (PD98059), Rac1 knockdown\",\n      \"journal\": \"Cellular physiology and biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — pathway placement via inhibitor and RNAi with proteomic screen, no direct binding demonstrated\",\n      \"pmids\": [\"30562745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Crystal structure of MacroD1 in complex with ADP-ribose reveals that the β5-α10 switch loop mediates substrate recognition, conserved Phe272 orients the distal ribose of ADPR, and a hydrogen-bond network positions the catalytic water for hydrolysis. MacroD1 is recruited to DNA damage sites via recognition of ADP-ribosylation, and its hydrolase activity is essential for DNA damage repair.\",\n      \"method\": \"X-ray crystallography (structure of MacroD1-ADPR complex), site-directed mutagenesis of catalytic residues, in vitro hydrolase assay, live-cell imaging of DNA damage recruitment\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure plus mutagenesis plus in vitro activity assay plus cellular localization with functional consequence\",\n      \"pmids\": [\"32683309\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MACROD1 localizes predominantly to mitochondria of skeletal muscle (confirmed with monoclonal antibodies against endogenous protein), and loss of MACROD1 disrupts mitochondrial morphology. BioID interactome mapping showed that MACROD1 interactors are enriched for mitochondrial proteins and suggest a role in mitochondrial RNA metabolism.\",\n      \"method\": \"Monoclonal antibody immunofluorescence/fractionation, MACROD1 knockout cells, BioID proximity labeling, gene ontology analysis\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — endogenous protein localization with validated antibodies, KO morphological phenotype, and BioID interactome\",\n      \"pmids\": [\"32427867\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Knockout of Macrod1 in mice results in a female-specific motor-coordination defect, consistent with its mitochondrial function in tissues relevant to motor control.\",\n      \"method\": \"Macrod1 gene knockout mouse model, standardized behavioral testing battery\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined behavioral/motor phenotype, but molecular mechanism not directly dissected\",\n      \"pmids\": [\"33578760\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Macrod1 suppresses diabetic cardiomyopathy by inhibiting PARP1 expression, thereby reducing NAD+ consumption and activating SIRT3-mediated antioxidative stress signaling (PARP1-NAD+-SIRT3 axis). Cardiac-specific overexpression of Macrod1 partially reversed mitochondrial dysfunction and oxidative stress in a DCM mouse model.\",\n      \"method\": \"Macrod1 KO and cardiac-specific overexpression mouse models, STZ/HFD diabetic cardiomyopathy model, Western blot, NAD+ measurement, SIRT3 activity assay, primary cardiomyocyte experiments\",\n      \"journal\": \"Acta pharmacologica Sinica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO and OE mouse models with pathway-level mechanistic readouts, single lab\",\n      \"pmids\": [\"38459256\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"LRP16 acts as a negative regulator of insulin action and adipogenesis in 3T3-L1 adipocytes by activating the mTOR signaling pathway, which promotes TNF-α secretion and suppresses IRS-1/PI3K/Akt phosphorylation and PPARγ expression; rapamycin treatment rescued these effects.\",\n      \"method\": \"Overexpression and siRNA knockdown in 3T3-L1 cells, glucose uptake assay, Western blot of signaling proteins, rapamycin inhibitor rescue\",\n      \"journal\": \"Hormone and metabolic research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — pathway placement via pharmacological rescue, no direct biochemical binding to mTOR complex\",\n      \"pmids\": [\"23389992\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MACROD1 (LRP16) is a mitochondria-localized mono-ADP-ribose hydrolase whose macrodomain catalyzes removal of ADP-ribose from modified proteins and DNA ends (with Phe272 and a conserved hydrogen-bond network critical for catalysis); it also functions as a nuclear coactivator of ERα, AR, and NF-κB by forming direct complexes with these factors, and operates as a scaffold assembling PARP1-IKKγ and PKR-IKKβ complexes to amplify DNA-damage-induced NF-κB signaling, while cytoplasmic sequestration by keratin 18 limits its nuclear availability and its mitochondrial function controls NAD+ homeostasis through restraint of PARP1 to activate SIRT3-mediated antioxidant responses.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MACROD1 (also known as LRP16) is a macrodomain-containing mono-ADP-ribose hydrolase that operates in both mitochondria and the nucleus to regulate ADP-ribosylation signaling, DNA damage repair, steroid receptor transcription, and NF-κB activation. Its macrodomain catalyzes hydrolytic removal of ADP-ribose from modified proteins and DNA ends, with crystal structures revealing that Phe272 and a conserved hydrogen-bond network orient the catalytic water for substrate cleavage, and this enzymatic activity is required for recruitment to and repair of DNA damage sites [PMID:32683309, PMID:29410655]. In the nucleus, MACROD1 functions as a transcriptional coactivator by directly binding ERα, AR, and the NF-κB p65 subunit, and as a scaffold assembling PARP1–IKKγ and PKR–IKKβ signaling complexes that amplify DNA-damage-induced NF-κB activation and confer chemoresistance [PMID:17914104, PMID:19022849, PMID:21483817, PMID:25735744, PMID:28820388]. In mitochondria, where the endogenous protein predominantly localizes, MACROD1 maintains organelle morphology and NAD⁺ homeostasis by restraining PARP1, thereby activating SIRT3-mediated antioxidant responses and protecting against diabetic cardiomyopathy [PMID:32427867, PMID:38459256].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Initial characterization established that MACROD1 (LRP16) is an estrogen- and androgen-responsive gene whose overexpression drives cell cycle progression, raising the question of how it contributes to hormone-dependent proliferation.\",\n      \"evidence\": \"LRP16 promoter assays and flow cytometry in MCF-7 cells showing S-phase entry and cyclin E upregulation\",\n      \"pmids\": [\"12790785\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct interaction with hormone receptors demonstrated\", \"Mechanism linking LRP16 to cyclin E induction unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"The molecular basis of LRP16's role in estrogen signaling was resolved: it physically binds the ERα AF-1 domain and coactivates ERα-dependent transcription, establishing it as a bona fide nuclear receptor coactivator.\",\n      \"evidence\": \"GST pulldown, co-immunoprecipitation, mammalian two-hybrid, and siRNA knockdown with reporter readout\",\n      \"pmids\": [\"17914104\", \"17893710\", \"18206366\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether coactivation requires enzymatic activity was unknown\", \"Structural basis of ERα–LRP16 interaction not determined\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"The coactivator function was generalized beyond ERα: LRP16's macrodomain directly binds androgen receptor and at least four additional nuclear receptors, and RNAi demonstrated functional dependence of AR-driven proliferation on LRP16.\",\n      \"evidence\": \"Co-IP and GST pulldown mapping the macro domain as the AR-interacting region, luciferase reporter and proliferation assays in LNCaP cells\",\n      \"pmids\": [\"19022849\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether macrodomain enzymatic activity is required for coactivation remained untested\", \"In vivo relevance not established\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"A regulatory mechanism controlling MACROD1 nuclear availability was identified: keratin 18 sequesters it in the cytoplasm, attenuating ERα-mediated transcription and estrogen-driven cell cycle progression.\",\n      \"evidence\": \"Yeast two-hybrid, GST pulldown, co-IP, nuclear/cytoplasmic fractionation, and BrdU incorporation in MCF-7 cells\",\n      \"pmids\": [\"20035625\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether K18 interaction is regulated by post-translational modification unknown\", \"Physiological contexts where K18 sequestration is rate-limiting not defined\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"MACROD1 was placed in the NF-κB pathway: it associates with p65, is required for formation of the NF-κB/p300/CBP transactivation complex after TNF-α stimulation, and its loss sensitizes cells to TNF-α-induced apoptosis — distinguishing a role in transactivation from nuclear translocation.\",\n      \"evidence\": \"GST pulldown, co-IP, luciferase reporter, ChIP, and Annexin V apoptosis assay\",\n      \"pmids\": [\"21483817\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether NF-κB coactivation and steroid receptor coactivation are mutually exclusive or concurrent was unclear\", \"No structural detail of p65–LRP16 interface\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"The scaffold function of MACROD1 in DNA damage-induced NF-κB signaling was defined: it constitutively assembles a PARP1–IKKγ preassembly complex that recruits PIASy for IKKγ SUMOylation after DSBs, in a Ku70/Ku80-dependent manner.\",\n      \"evidence\": \"Co-IP, GST pulldown, proximity ligation assay, siRNA epistasis, and NF-κB reporter in response to etoposide-induced DSBs\",\n      \"pmids\": [\"25735744\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MACROD1's hydrolase activity contributes to complex assembly not tested\", \"Stoichiometry and dynamics of the preassembly complex unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"A second scaffold axis was discovered: MACROD1 activates PKR and nucleates a PKR–IKKβ ternary complex that sustains PAR-dependent NF-κB signaling after DNA damage, conferring chemoresistance that can be reversed by the small molecule MRS2578.\",\n      \"evidence\": \"Co-IP, kinase assays, RNAi, MRS2578 pharmacological disruption, and xenograft tumor model\",\n      \"pmids\": [\"28820388\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Binding mode of MRS2578 to MACROD1 not structurally resolved\", \"Whether PKR scaffold function operates outside DNA damage contexts unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"The intrinsic enzymatic activity of MACROD1 was biochemically characterized: it is a mono-ADP-ribose hydrolase that removes ADP-ribose from phosphorylated DNA ends, and the endogenous protein localizes predominantly to mitochondria.\",\n      \"evidence\": \"Subcellular fractionation and immunofluorescence of endogenous protein, in vitro hydrolase assay with phosphorylated dsDNA substrates\",\n      \"pmids\": [\"29410655\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo mitochondrial substrates not identified\", \"Relationship between mitochondrial localization and nuclear coactivator functions unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"The structural mechanism of catalysis was determined at atomic resolution: the β5-α10 switch loop mediates substrate recognition, Phe272 orients the distal ribose, and the hydrolase activity is essential for recruitment to and repair of DNA damage sites.\",\n      \"evidence\": \"X-ray crystallography of MacroD1–ADPR complex, site-directed mutagenesis, in vitro hydrolase assay, live-cell imaging of DNA damage recruitment\",\n      \"pmids\": [\"32683309\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether catalytic-dead mutant retains scaffold/coactivator functions not tested\", \"No structure of full-length MACROD1 or in complex with protein substrates\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Mitochondrial function was validated with knockout cells: loss of MACROD1 disrupts mitochondrial morphology, and BioID proximity labeling revealed an interactome enriched for mitochondrial RNA metabolism factors.\",\n      \"evidence\": \"Monoclonal antibody localization, MACROD1 knockout cells, BioID interactome profiling\",\n      \"pmids\": [\"32427867\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific mitochondrial RNA substrates not identified\", \"Whether morphology defect is due to loss of hydrolase activity or protein interactions not dissected\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"In vivo loss of Macrod1 produces a female-specific motor coordination defect in mice, linking its mitochondrial function to neuromuscular physiology.\",\n      \"evidence\": \"Macrod1 knockout mouse model with standardized behavioral testing\",\n      \"pmids\": [\"33578760\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism underlying female specificity not determined\", \"Tissue-specific basis (skeletal muscle vs. brain) not resolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"A cardioprotective axis was delineated: MACROD1 suppresses PARP1, preserving NAD⁺ pools and activating SIRT3-dependent antioxidant signaling, and cardiac-specific overexpression rescues diabetic cardiomyopathy in mice.\",\n      \"evidence\": \"Macrod1 KO and cardiac-specific overexpression in STZ/HFD diabetic cardiomyopathy mouse model, NAD⁺ measurement, SIRT3 activity assay\",\n      \"pmids\": [\"38459256\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether MACROD1 directly modifies PARP1 ADP-ribosylation or acts indirectly to suppress PARP1 expression not resolved\", \"Single-lab finding awaiting independent replication\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The central unresolved question is how MACROD1's enzymatic hydrolase activity, its scaffold/coactivator functions, and its dual mitochondrial–nuclear localization are coordinated in vivo, and what controls the balance between these compartments.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No in vivo catalytic-dead knock-in to separate enzymatic from scaffold roles\", \"Mitochondrial targeting signal and regulated nuclear import mechanism not fully defined\", \"Identity of endogenous mitochondrial ADP-ribosylated substrates unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [9, 11]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 1, 6]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [7, 8]},\n      {\"term_id\": \"GO:0140097\", \"supporting_discovery_ids\": [9, 11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [9, 12]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1, 6, 7, 11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0073894\", \"supporting_discovery_ids\": [11]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [11]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [6, 7, 8]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 6, 7, 8, 10]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 1, 6]}\n    ],\n    \"complexes\": [\n      \"PARP1-IKKγ-MACROD1 preassembly complex\",\n      \"PKR-IKKβ-MACROD1 ternary complex\"\n    ],\n    \"partners\": [\n      \"ESR1\",\n      \"AR\",\n      \"RELA\",\n      \"PARP1\",\n      \"IKBKG\",\n      \"EIF2AK2\",\n      \"KRT18\",\n      \"IKBKB\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}