{"gene":"PNN","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":2003,"finding":"PNN/DRS protein associates preferentially with spliced mRNAs in vitro (by immunoprecipitation), binds to mRNAs at a position immediately upstream of the splice junction (shown by oligonucleotide-directed RNase H digestion), and interacts directly with RNPS1, a pre-mRNA splicing factor and exon-exon junction complex component. Overexpression of the amino-terminal fragment of PNN that directly interacts with RNPS1 blocks pre-mRNA splicing. Suppression of PNN leads to nuclear accumulation of bulk poly(A)+ RNA, implicating PNN in mRNA export via its interaction with RNPS1.","method":"Immunoprecipitation, RNase H digestion, heterokaryon assay, overexpression, RNA interference","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (Co-IP, RNase H mapping, heterokaryon assay, overexpression, RNAi) in a single rigorous study establishing binding partner, binding location, and functional consequence","pmids":["14517304"],"is_preprint":false},{"year":2003,"finding":"PNN/DRS/memA interacts with SR-rich proteins SRp75, SRm300, and a novel 130-kDa protein SRrp130 via its C-terminal polyserine/RS motif, as determined by yeast two-hybrid analysis and co-immunoprecipitation. These proteins co-localize in nuclear speckles with pre-mRNA splicing machinery, suggesting PNN is part of a multiprotein complex involved in pre-mRNA processing.","method":"Yeast two-hybrid, co-immunoprecipitation, immunofluorescence co-localization","journal":"Investigative ophthalmology & visual science","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — yeast two-hybrid plus co-IP plus co-localization, single lab, multiple complementary methods","pmids":["14578391"],"is_preprint":false},{"year":2004,"finding":"PNN interacts with the transcriptional corepressor CtBP1 via in vitro pull-down and in vivo co-immunoprecipitation, and this interaction enables PNN to relieve CtBP1-mediated repression of the E-cadherin promoter, as shown by reporter assays combined with overexpression and RNA interference experiments.","method":"In vitro pull-down, co-immunoprecipitation, reporter assay, overexpression, RNA interference, immunofluorescence","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal interaction confirmed by in vitro pulldown and in vivo co-IP, functional consequence shown by promoter reporter assay with both gain- and loss-of-function experiments","pmids":["15542832"],"is_preprint":false},{"year":2005,"finding":"RNAi-mediated knockdown of PNN in human corneal epithelial cells leads to loss of cell-cell adhesion, altered cell shape, downregulation of E-cadherin and desmosomal proteins (desmoplakin, desmoglein), redistribution of keratin filaments away from desmosomes, and altered distribution of SR proteins and SRm300. A conservatively mutated rescue construct restores cell-cell adhesion, confirming specificity.","method":"shRNAi knockdown, rescue construct, immunofluorescence, Western blot","journal":"Molecular vision","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean RNAi knockdown with specific rescue control, multiple molecular readouts, defining PNN's role in epithelial cell-cell adhesion maintenance","pmids":["15735603"],"is_preprint":false},{"year":2007,"finding":"CtBP recruits PNN to CtBP-associated chromatin complexes at the E-cadherin promoter, leading to PNN-dependent chromatin remodeling. CtBP and PNN can differentially modulate E-cadherin mRNA splicing, with RNA polymerase II serving as an interface, establishing a novel mechanism linking CtBP-mediated transcriptional regulation to mRNA splicing of E-cadherin.","method":"Co-immunoprecipitation, chromatin immunoprecipitation, reporter assay, splicing assay","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP, co-IP, and functional splicing assays together establish a transcription-splicing coupling mechanism with multiple orthogonal approaches","pmids":["18086895"],"is_preprint":false},{"year":2000,"finding":"Overexpression of full-length PNN in cultured MDCK epithelial cells results in hyperstable cell adhesion and markedly reduced cell migration after wound scraping. During corneal wound healing in vivo, PNN dissociates from desmosomes in migrating epithelial cells and returns after wound closure, correlating PNN desmosomal localization with epithelial quiescence.","method":"Transfection/overexpression, wound scratch migration assay, immunofluorescence, immunoelectron microscopy","journal":"Investigative ophthalmology & visual science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment tied to functional consequence (migration inhibition), in vitro and in vivo, single lab","pmids":["10798648"],"is_preprint":false},{"year":2012,"finding":"Pnn depletion by RNAi in MCF-7 cells induces cellular apoptosis, disrupts nuclear speckles, reduces SR protein levels, and alters alternative splicing of SRSF1, Bcl-x (shifting toward pro-apoptotic Bcl-xS), and ICAD. Apoptosis is rescued by overexpression of SRSF1, which restores Bcl-xL and functionless ICAD splicing, placing Pnn upstream of SRSF1 in the regulation of apoptotic alternative splicing. Pnn homozygous knockout in mice causes early embryonic lethality.","method":"RNA interference, RT-PCR for alternative splicing, overexpression rescue, flow cytometry (apoptosis), mouse knockout","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis via rescue experiment (SRSF1 overexpression rescues Pnn-depletion apoptosis), multiple orthogonal assays, in vitro and in vivo","pmids":["22454513"],"is_preprint":false},{"year":2009,"finding":"Conditional inactivation of Pnn in developing mouse eye ectoderm (via Pax6-Cre) causes severe malformation of cornea and lens, loss of corneal epithelial identity (loss of K12, gain of K10/K14), squamous metaplasia correlated with elevated β-catenin activity and Tcf4 level, and misregulated p68 RNA helicase in mutant corneal epithelium.","method":"Conditional knockout (Cre-lox), histology, immunohistochemistry, mouse genetics","journal":"Investigative ophthalmology & visual science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional knockout with defined molecular phenotype (β-catenin/Tcf4 activation, keratin switching), single lab","pmids":["19892877"],"is_preprint":false},{"year":2013,"finding":"ESRP1 and PNN physically associate in protein complexes within nuclear speckles (by co-immunoprecipitation and deconvolution microscopy) in corneal epithelial cells. Whole transcriptome array analysis of PNN or ESRP1 knockdown cells reveals distinct but overlapping subsets of alternatively spliced genes, including PAX6(5a), FOXJ3, ARHGEF11, and SLC37A2, supporting a role for PNN in epithelial-type alternative splicing regulation.","method":"Co-immunoprecipitation, deconvolution microscopy, transcriptome array, RT-PCR validation, shRNA knockdown","journal":"Investigative ophthalmology & visual science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP plus genome-wide splicing array plus RT-PCR validation, single lab, multiple orthogonal methods","pmids":["23299472"],"is_preprint":false},{"year":2017,"finding":"PNN physically interacts with SNRPA1 and SNRPD1 (spliceosomal components) in human pluripotent stem cells, as shown by co-immunoprecipitation. PNN depletion leads to loss of pluripotency and blocks hiPS generation. PNN co-localizes with hPS spliceosomes and positively influences hPS spliceosome assembly.","method":"Co-immunoprecipitation, RNAi knockdown, immunofluorescence, gene expression profiling","journal":"Stem cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP establishes protein interaction, functional knockdown shows loss-of-function phenotype; single lab","pmids":["28595116"],"is_preprint":false},{"year":2014,"finding":"PNN knockdown in human corneal epithelial cells (HCET) causes altered alternative splicing of a specific subset of long non-coding RNAs (lncRNAs) including Has2as, RP11-322M19.1, and RP11-18I14.1, affecting cassette exon inclusion and alternative splice site usage. Pnn-deficient mouse corneas show differential splicing patterns in lncRNA orthologues, establishing PNN's role in lncRNA splicing regulation in corneal epithelium.","method":"RNAi knockdown, RT-PCR, in situ hybridization, Pnn conditional knockout mouse","journal":"Molecular vision","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RT-PCR splicing assays confirmed in both cell culture knockdown and conditional knockout mouse, single lab","pmids":["25489234"],"is_preprint":false},{"year":2022,"finding":"Inducible neuron-specific Pnn deficiency in mice increases SRSF2 expression and decreases SRSF1 expression in brain tissue, elevates ROS generators (NOX-1, NOX-2) and antioxidant proteins (GR, HO-1, NQO-1), and increases oxidized proteins in cortical and hippocampal neurons. Upon MCAO-induced stroke, neuronal Pnn-deficient mice show increased cerebral infarct area and elevated pro-apoptotic protein expression, establishing Pnn's neuroprotective role against ischemia-reperfusion injury through SRSF1/SRSF2 splicing regulation.","method":"Inducible conditional knockout, MCAO stroke model, Western blot, immunofluorescence, ROS measurement","journal":"Antioxidants (Basel, Switzerland)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional knockout with defined molecular (SRSF1/2 imbalance, oxidative stress markers) and functional (infarct area) phenotype; single lab","pmids":["35326115"],"is_preprint":false},{"year":1999,"finding":"Sequence analysis identified that MEMA/PNN protein contains three coiled-coil domains and one glycine loop domain, and is identical to a 160 kDa nuclear 'domain rich in serines' (DRS) protein that occurs free in the nucleoplasm and in U2-ribonucleoprotein structures, establishing its presence in RNA-associated nuclear complexes.","method":"Subtractive hybridization, sequence analysis, expression analysis","journal":"Biochimica et biophysica acta","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational sequence analysis and expression; no direct functional experiment on the protein","pmids":["10095061"],"is_preprint":false},{"year":2020,"finding":"In primary cultured neurons and astrocytes subjected to oxygen-glucose deprivation (OGD), Pnn expression increases during OGD and decreases during reoxygenation in neurons, while in astrocytes Pnn expression decreases with OGD and increases during reoxygenation. Cytoplasmic translocation of Pnn (normally nuclear speckle-localized) is observed in neurons under OGD/reoxygenation but not in astrocytes, demonstrating cell-type-specific redistribution under ischemic stress.","method":"OGD model, MCAO mouse model, immunofluorescence, Western blot, primary cell culture","journal":"Brain sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct subcellular localization experiment in multiple cell types with ischemic stress model, functional implication of nuclear-cytoplasmic shift; single lab","pmids":["33027948"],"is_preprint":false}],"current_model":"PNN (pinin/DRS/memA) is a multifunctional nuclear speckle-associated phosphoprotein that acts at the interface of transcription and mRNA processing: it binds spliced mRNPs near exon-exon junctions via interaction with RNPS1 to facilitate mRNA export, interacts with SR-rich splicing factors (SRp75, SRm300, ESRP1, SRSF1) to regulate alternative splicing of specific epithelial gene subsets (including apoptosis regulators Bcl-x and ICAD), and modulates transcription by binding the corepressor CtBP1 to relieve repression of the E-cadherin promoter while also coupling CtBP-mediated transcriptional regulation to mRNA splicing through RNA Pol II; at the cell periphery, PNN associates with desmosomes and its desmosomal localization promotes epithelial quiescence, while loss of PNN causes cell adhesion failure, epithelial-to-mesenchymal transition, apoptosis (through SRSF1-mediated Bcl-xS upregulation), and embryonic lethality in mice."},"narrative":{"mechanistic_narrative":"PNN (pinin/DRS/memA) is a nuclear speckle-associated phosphoprotein that operates at the interface of transcription, mRNA processing, and epithelial cell adhesion [PMID:14517304, PMID:15735603]. In the nucleus it associates preferentially with spliced mRNAs at positions immediately upstream of exon-exon junctions through direct interaction with the splicing/EJC factor RNPS1, and its suppression causes nuclear accumulation of poly(A)+ RNA, linking PNN to mRNA export [PMID:14517304]. PNN assembles into multiprotein splicing complexes via its C-terminal RS-rich motif, interacting with SR-rich proteins (SRp75, SRm300, SRrp130) and with ESRP1 to regulate epithelial-type alternative splicing of defined gene subsets, including PAX6(5a), FOXJ3, and a class of long non-coding RNAs [PMID:14578391, PMID:23299472, PMID:25489234]. PNN acts upstream of SRSF1 to control apoptotic splicing decisions: its depletion shifts Bcl-x toward the pro-apoptotic Bcl-xS isoform and alters ICAD splicing, driving apoptosis that is rescued by SRSF1 [PMID:22454513]. Through interaction with the corepressor CtBP1, PNN relieves CtBP1-mediated repression of the E-cadherin promoter and is recruited to CtBP-associated chromatin, coupling transcriptional regulation to E-cadherin mRNA splicing via RNA polymerase II [PMID:15542832, PMID:18086895]. At the cell periphery, PNN localizes to desmosomes where it promotes stable cell-cell adhesion and epithelial quiescence; its loss downregulates E-cadherin and desmosomal proteins and causes adhesion failure, while overexpression hyperstabilizes adhesion and suppresses migration [PMID:15735603, PMID:10798648]. PNN is required for corneal epithelial identity and for pluripotency, and its homozygous knockout is embryonic lethal in mice [PMID:22454513, PMID:19892877, PMID:28595116].","teleology":[{"year":2003,"claim":"Established PNN as an mRNA-binding factor coupling splicing to export, answering whether it has a direct role in RNA metabolism rather than being merely speckle-resident.","evidence":"Co-IP, RNase H mapping, heterokaryon assay, overexpression and RNAi in human cells","pmids":["14517304"],"confidence":"High","gaps":["Does not define the RNA sequence/structure determinant of binding","Mechanism of export coupling beyond RNPS1 interaction not resolved"]},{"year":2003,"claim":"Showed PNN is a stable component of SR-rich splicing complexes in speckles, establishing the structural basis for its splicing role via its RS-rich motif.","evidence":"Yeast two-hybrid, co-IP, immunofluorescence co-localization","pmids":["14578391"],"confidence":"Medium","gaps":["SRrp130 identity not molecularly defined","Functional consequence of each interaction on specific transcripts not tested"]},{"year":2004,"claim":"Linked PNN to transcriptional control by showing it antagonizes CtBP1 corepression at the E-cadherin promoter, connecting it to epithelial gene regulation.","evidence":"In vitro pull-down, co-IP, promoter reporter assays with gain/loss of function","pmids":["15542832"],"confidence":"High","gaps":["Structural basis of PNN-CtBP1 interaction unknown","Whether de-repression generalizes beyond E-cadherin untested here"]},{"year":2005,"claim":"Defined PNN as required for epithelial cell-cell adhesion, demonstrating that its nuclear/splicing functions translate to a junctional phenotype.","evidence":"shRNA knockdown with rescue control, immunofluorescence, Western blot in corneal epithelial cells","pmids":["15735603"],"confidence":"High","gaps":["Does not separate direct desmosomal role from indirect transcriptional/splicing effects","Causal ordering of E-cadherin loss vs adhesion failure unresolved"]},{"year":2007,"claim":"Resolved how PNN bridges transcription and splicing, showing CtBP recruits it to chromatin and that PNN and CtBP modulate E-cadherin splicing through RNA Pol II.","evidence":"ChIP, co-IP, reporter and splicing assays","pmids":["18086895"],"confidence":"High","gaps":["Direct chromatin-remodeling activity of PNN not biochemically defined","Generality of Pol II coupling to other genes untested"]},{"year":2012,"claim":"Placed PNN upstream of SRSF1 in apoptotic splicing control and established its essentiality in development via embryonic lethality of knockout mice.","evidence":"RNAi, RT-PCR splicing analysis, SRSF1 overexpression rescue, flow cytometry, mouse knockout","pmids":["22454513"],"confidence":"High","gaps":["Mechanism by which PNN sustains SRSF1 levels not defined","Cause of embryonic lethality not mapped to a specific splicing target"]},{"year":2009,"claim":"Showed PNN is required in vivo for corneal/lens epithelial identity, linking its loss to Wnt/β-catenin activation and keratin switching.","evidence":"Pax6-Cre conditional knockout, histology, immunohistochemistry","pmids":["19892877"],"confidence":"Medium","gaps":["Whether β-catenin/Tcf4 activation is direct or downstream of adhesion loss unresolved","p68 helicase misregulation mechanism unknown"]},{"year":2013,"claim":"Identified ESRP1 as a PNN partner and defined overlapping epithelial alternative-splicing programs, broadening the targets of PNN-dependent splicing.","evidence":"Reciprocal co-IP, deconvolution microscopy, transcriptome array with RT-PCR validation, shRNA","pmids":["23299472"],"confidence":"Medium","gaps":["Direct versus indirect splicing regulation for each target not distinguished","Single cell-type context"]},{"year":2014,"claim":"Extended PNN's splicing role to long non-coding RNAs, showing it shapes lncRNA exon usage in corneal epithelium.","evidence":"RNAi knockdown, RT-PCR, in situ hybridization, conditional knockout mouse","pmids":["25489234"],"confidence":"Medium","gaps":["Functional consequences of altered lncRNA isoforms unknown","Mechanism of lncRNA target selection unresolved"]},{"year":2017,"claim":"Demonstrated PNN is required for pluripotency and influences spliceosome assembly, via interaction with core spliceosomal proteins.","evidence":"Co-IP with SNRPA1/SNRPD1, RNAi, immunofluorescence, expression profiling in hiPSCs","pmids":["28595116"],"confidence":"Medium","gaps":["How PNN promotes spliceosome assembly mechanistically not defined","Direct vs indirect effect on pluripotency factors untested"]},{"year":2020,"claim":"Revealed cell-type-specific PNN redistribution under ischemic stress, with nuclear-to-cytoplasmic translocation in neurons but not astrocytes.","evidence":"OGD and MCAO models, immunofluorescence, Western blot in primary cells","pmids":["33027948"],"confidence":"Medium","gaps":["Functional role of cytoplasmic PNN under stress not established","Trigger for translocation unknown"]},{"year":2022,"claim":"Established a neuroprotective role for PNN against ischemia-reperfusion injury mediated through SRSF1/SRSF2 splicing balance and oxidative stress control.","evidence":"Inducible neuron-specific knockout, MCAO stroke model, Western blot, ROS measurement","pmids":["35326115"],"confidence":"Medium","gaps":["Specific splicing targets driving neuroprotection not identified","Causal link between SRSF imbalance and oxidative damage not directly tested"]},{"year":null,"claim":"How PNN's distinct activities—mRNP export, alternative splicing, CtBP-coupled transcription, and desmosomal adhesion—are mechanistically coordinated and what governs its context-dependent localization remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of PNN domains in complex with partners","No unifying mechanism linking nuclear and junctional pools","Direct RNA-binding specificity not defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[0]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[2,4]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,8]}],"localization":[{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[12]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[3,5]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[13]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[0,6,8,10]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[2,4]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[6,11]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[7,9]}],"complexes":["nuclear speckle","spliceosome","exon-exon junction complex","CtBP-associated chromatin complex"],"partners":["RNPS1","CTBP1","SRSF1","ESRP1","SRM300","SRSF11","SNRPA1","SNRPD1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9H307","full_name":"Pinin","aliases":["140 kDa nuclear and cell adhesion-related phosphoprotein","Desmosome-associated protein","Domain-rich serine protein","DRS protein","DRSP","Melanoma metastasis clone A protein","Nuclear protein SDK3","SR-like protein"],"length_aa":717,"mass_kda":81.6,"function":"Transcriptional activator binding to the E-box 1 core sequence of the E-cadherin promoter gene; the core-binding sequence is 5'CAGGTG-3'. Capable of reversing CTBP1-mediated transcription repression. Auxiliary component of the splicing-dependent multiprotein exon junction complex (EJC) deposited at splice junction on mRNAs. The EJC is a dynamic structure consisting of core proteins and several peripheral nuclear and cytoplasmic associated factors that join the complex only transiently either during EJC assembly or during subsequent mRNA metabolism. Participates in the regulation of alternative pre-mRNA splicing. Associates to spliced mRNA within 60 nt upstream of the 5'-splice sites. Component of the PSAP complex which binds RNA in a sequence-independent manner and is proposed to be recruited to the EJC prior to or during the splicing process and to regulate specific excision of introns in specific transcription subsets. Involved in the establishment and maintenance of epithelia cell-cell adhesion. Potential tumor suppressor for renal cell carcinoma","subcellular_location":"Nucleus speckle; Cell junction, desmosome","url":"https://www.uniprot.org/uniprotkb/Q9H307/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/PNN","classification":"Common Essential","n_dependent_lines":1129,"n_total_lines":1208,"dependency_fraction":0.9346026490066225},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"PRPF4B","stoichiometry":4.0},{"gene":"CALM3","stoichiometry":0.2},{"gene":"CD2BP2","stoichiometry":0.2},{"gene":"CPSF6","stoichiometry":0.2},{"gene":"DDX21","stoichiometry":0.2},{"gene":"HIST2H2BE","stoichiometry":0.2},{"gene":"NUMA1","stoichiometry":0.2},{"gene":"RBM14","stoichiometry":0.2},{"gene":"RBM33","stoichiometry":0.2},{"gene":"RBM39","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PNN","total_profiled":1310},"omim":[{"mim_id":"619744","title":"ZINC FINGER CCHC DOMAIN-CONTAINING PROTEIN 17; ZCCHC17","url":"https://www.omim.org/entry/619744"},{"mim_id":"616653","title":"PNN-INTERACTING SERINE/ARGININE-RICH PROTEIN; PNISR","url":"https://www.omim.org/entry/616653"},{"mim_id":"616344","title":"TETRATRICOPEPTIDE REPEAT DOMAIN-CONTAINING PROTEIN 23-LIKE; TTC23L","url":"https://www.omim.org/entry/616344"},{"mim_id":"606032","title":"SERINE/ARGININE REPETITIVE MATRIX PROTEIN 2; SRRM2","url":"https://www.omim.org/entry/606032"},{"mim_id":"603154","title":"PININ; PNN","url":"https://www.omim.org/entry/603154"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nuclear speckles","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PNN"},"hgnc":{"alias_symbol":["memA"],"prev_symbol":[]},"alphafold":{"accession":"Q9H307","domains":[{"cath_id":"-","chopping":"2-34_137-207","consensus_level":"medium","plddt":88.1,"start":2,"end":207},{"cath_id":"-","chopping":"232-309","consensus_level":"medium","plddt":76.7432,"start":232,"end":309}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H307","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H307-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H307-F1-predicted_aligned_error_v6.png","plddt_mean":57.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PNN","jax_strain_url":"https://www.jax.org/strain/search?query=PNN"},"sequence":{"accession":"Q9H307","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9H307.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9H307/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H307"}},"corpus_meta":[{"pmid":"32626660","id":"PMC_32626660","title":"RNA-Seq Profiling of Serum Exosomal Circular RNAs Reveals Circ-PNN as a Potential Biomarker for Human Colorectal Cancer.","date":"2020","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/32626660","citation_count":87,"is_preprint":false},{"pmid":"24611673","id":"PMC_24611673","title":"Catalytic mechanisms of direct pyrrole synthesis via dehydrogenative coupling mediated by PNP-Ir or PNN-Ru pincer complexes: crucial role of proton-transfer shuttles in the PNP-Ir system.","date":"2014","source":"Journal of the American Chemical Society","url":"https://pubmed.ncbi.nlm.nih.gov/24611673","citation_count":71,"is_preprint":false},{"pmid":"15542832","id":"PMC_15542832","title":"Nuclear speckle-associated protein Pnn/DRS binds to the transcriptional corepressor CtBP and relieves CtBP-mediated repression of the E-cadherin gene.","date":"2004","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15542832","citation_count":64,"is_preprint":false},{"pmid":"14517304","id":"PMC_14517304","title":"Nuclear Pnn/DRS protein binds to spliced mRNPs and participates in mRNA processing and export via interaction with RNPS1.","date":"2003","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/14517304","citation_count":61,"is_preprint":false},{"pmid":"14578391","id":"PMC_14578391","title":"Pinin/DRS/memA interacts with SRp75, SRm300 and SRrp130 in corneal epithelial cells.","date":"2003","source":"Investigative ophthalmology & visual science","url":"https://pubmed.ncbi.nlm.nih.gov/14578391","citation_count":54,"is_preprint":false},{"pmid":"10645008","id":"PMC_10645008","title":"Characterization of the gene encoding pinin/DRS/memA and evidence for its potential tumor suppressor function.","date":"2000","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/10645008","citation_count":41,"is_preprint":false},{"pmid":"20044083","id":"PMC_20044083","title":"Tumor classification by combining PNN classifier ensemble with neighborhood rough set based gene reduction.","date":"2009","source":"Computers in biology and medicine","url":"https://pubmed.ncbi.nlm.nih.gov/20044083","citation_count":39,"is_preprint":false},{"pmid":"10798648","id":"PMC_10798648","title":"Role of cell adhesion-associated protein, pinin (DRS/memA), in corneal epithelial migration.","date":"2000","source":"Investigative ophthalmology & visual science","url":"https://pubmed.ncbi.nlm.nih.gov/10798648","citation_count":36,"is_preprint":false},{"pmid":"15735603","id":"PMC_15735603","title":"Reduction of Pnn by RNAi induces loss of cell-cell adhesion between human corneal epithelial cells.","date":"2005","source":"Molecular 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ICAD.","date":"2012","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/22454513","citation_count":32,"is_preprint":false},{"pmid":"19892877","id":"PMC_19892877","title":"Disruption of mouse corneal epithelial differentiation by conditional inactivation of pnn.","date":"2009","source":"Investigative ophthalmology & visual science","url":"https://pubmed.ncbi.nlm.nih.gov/19892877","citation_count":27,"is_preprint":false},{"pmid":"31772567","id":"PMC_31772567","title":"Neuronal Pentraxin 2 Binds PNNs and Enhances PNN Formation.","date":"2019","source":"Neural plasticity","url":"https://pubmed.ncbi.nlm.nih.gov/31772567","citation_count":26,"is_preprint":false},{"pmid":"28595116","id":"PMC_28595116","title":"The unique spliceosome signature of human pluripotent stem cells is mediated by SNRPA1, SNRPD1, and PNN.","date":"2017","source":"Stem cell 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Overexpression of the amino-terminal fragment of PNN that directly interacts with RNPS1 blocks pre-mRNA splicing. Suppression of PNN leads to nuclear accumulation of bulk poly(A)+ RNA, implicating PNN in mRNA export via its interaction with RNPS1.\",\n      \"method\": \"Immunoprecipitation, RNase H digestion, heterokaryon assay, overexpression, RNA interference\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (Co-IP, RNase H mapping, heterokaryon assay, overexpression, RNAi) in a single rigorous study establishing binding partner, binding location, and functional consequence\",\n      \"pmids\": [\"14517304\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"PNN/DRS/memA interacts with SR-rich proteins SRp75, SRm300, and a novel 130-kDa protein SRrp130 via its C-terminal polyserine/RS motif, as determined by yeast two-hybrid analysis and co-immunoprecipitation. These proteins co-localize in nuclear speckles with pre-mRNA splicing machinery, suggesting PNN is part of a multiprotein complex involved in pre-mRNA processing.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, immunofluorescence co-localization\",\n      \"journal\": \"Investigative ophthalmology & visual science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — yeast two-hybrid plus co-IP plus co-localization, single lab, multiple complementary methods\",\n      \"pmids\": [\"14578391\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PNN interacts with the transcriptional corepressor CtBP1 via in vitro pull-down and in vivo co-immunoprecipitation, and this interaction enables PNN to relieve CtBP1-mediated repression of the E-cadherin promoter, as shown by reporter assays combined with overexpression and RNA interference experiments.\",\n      \"method\": \"In vitro pull-down, co-immunoprecipitation, reporter assay, overexpression, RNA interference, immunofluorescence\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal interaction confirmed by in vitro pulldown and in vivo co-IP, functional consequence shown by promoter reporter assay with both gain- and loss-of-function experiments\",\n      \"pmids\": [\"15542832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"RNAi-mediated knockdown of PNN in human corneal epithelial cells leads to loss of cell-cell adhesion, altered cell shape, downregulation of E-cadherin and desmosomal proteins (desmoplakin, desmoglein), redistribution of keratin filaments away from desmosomes, and altered distribution of SR proteins and SRm300. A conservatively mutated rescue construct restores cell-cell adhesion, confirming specificity.\",\n      \"method\": \"shRNAi knockdown, rescue construct, immunofluorescence, Western blot\",\n      \"journal\": \"Molecular vision\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean RNAi knockdown with specific rescue control, multiple molecular readouts, defining PNN's role in epithelial cell-cell adhesion maintenance\",\n      \"pmids\": [\"15735603\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"CtBP recruits PNN to CtBP-associated chromatin complexes at the E-cadherin promoter, leading to PNN-dependent chromatin remodeling. CtBP and PNN can differentially modulate E-cadherin mRNA splicing, with RNA polymerase II serving as an interface, establishing a novel mechanism linking CtBP-mediated transcriptional regulation to mRNA splicing of E-cadherin.\",\n      \"method\": \"Co-immunoprecipitation, chromatin immunoprecipitation, reporter assay, splicing assay\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP, co-IP, and functional splicing assays together establish a transcription-splicing coupling mechanism with multiple orthogonal approaches\",\n      \"pmids\": [\"18086895\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Overexpression of full-length PNN in cultured MDCK epithelial cells results in hyperstable cell adhesion and markedly reduced cell migration after wound scraping. During corneal wound healing in vivo, PNN dissociates from desmosomes in migrating epithelial cells and returns after wound closure, correlating PNN desmosomal localization with epithelial quiescence.\",\n      \"method\": \"Transfection/overexpression, wound scratch migration assay, immunofluorescence, immunoelectron microscopy\",\n      \"journal\": \"Investigative ophthalmology & visual science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment tied to functional consequence (migration inhibition), in vitro and in vivo, single lab\",\n      \"pmids\": [\"10798648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Pnn depletion by RNAi in MCF-7 cells induces cellular apoptosis, disrupts nuclear speckles, reduces SR protein levels, and alters alternative splicing of SRSF1, Bcl-x (shifting toward pro-apoptotic Bcl-xS), and ICAD. Apoptosis is rescued by overexpression of SRSF1, which restores Bcl-xL and functionless ICAD splicing, placing Pnn upstream of SRSF1 in the regulation of apoptotic alternative splicing. Pnn homozygous knockout in mice causes early embryonic lethality.\",\n      \"method\": \"RNA interference, RT-PCR for alternative splicing, overexpression rescue, flow cytometry (apoptosis), mouse knockout\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis via rescue experiment (SRSF1 overexpression rescues Pnn-depletion apoptosis), multiple orthogonal assays, in vitro and in vivo\",\n      \"pmids\": [\"22454513\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Conditional inactivation of Pnn in developing mouse eye ectoderm (via Pax6-Cre) causes severe malformation of cornea and lens, loss of corneal epithelial identity (loss of K12, gain of K10/K14), squamous metaplasia correlated with elevated β-catenin activity and Tcf4 level, and misregulated p68 RNA helicase in mutant corneal epithelium.\",\n      \"method\": \"Conditional knockout (Cre-lox), histology, immunohistochemistry, mouse genetics\",\n      \"journal\": \"Investigative ophthalmology & visual science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockout with defined molecular phenotype (β-catenin/Tcf4 activation, keratin switching), single lab\",\n      \"pmids\": [\"19892877\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"ESRP1 and PNN physically associate in protein complexes within nuclear speckles (by co-immunoprecipitation and deconvolution microscopy) in corneal epithelial cells. Whole transcriptome array analysis of PNN or ESRP1 knockdown cells reveals distinct but overlapping subsets of alternatively spliced genes, including PAX6(5a), FOXJ3, ARHGEF11, and SLC37A2, supporting a role for PNN in epithelial-type alternative splicing regulation.\",\n      \"method\": \"Co-immunoprecipitation, deconvolution microscopy, transcriptome array, RT-PCR validation, shRNA knockdown\",\n      \"journal\": \"Investigative ophthalmology & visual science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP plus genome-wide splicing array plus RT-PCR validation, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"23299472\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PNN physically interacts with SNRPA1 and SNRPD1 (spliceosomal components) in human pluripotent stem cells, as shown by co-immunoprecipitation. PNN depletion leads to loss of pluripotency and blocks hiPS generation. PNN co-localizes with hPS spliceosomes and positively influences hPS spliceosome assembly.\",\n      \"method\": \"Co-immunoprecipitation, RNAi knockdown, immunofluorescence, gene expression profiling\",\n      \"journal\": \"Stem cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP establishes protein interaction, functional knockdown shows loss-of-function phenotype; single lab\",\n      \"pmids\": [\"28595116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PNN knockdown in human corneal epithelial cells (HCET) causes altered alternative splicing of a specific subset of long non-coding RNAs (lncRNAs) including Has2as, RP11-322M19.1, and RP11-18I14.1, affecting cassette exon inclusion and alternative splice site usage. Pnn-deficient mouse corneas show differential splicing patterns in lncRNA orthologues, establishing PNN's role in lncRNA splicing regulation in corneal epithelium.\",\n      \"method\": \"RNAi knockdown, RT-PCR, in situ hybridization, Pnn conditional knockout mouse\",\n      \"journal\": \"Molecular vision\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RT-PCR splicing assays confirmed in both cell culture knockdown and conditional knockout mouse, single lab\",\n      \"pmids\": [\"25489234\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Inducible neuron-specific Pnn deficiency in mice increases SRSF2 expression and decreases SRSF1 expression in brain tissue, elevates ROS generators (NOX-1, NOX-2) and antioxidant proteins (GR, HO-1, NQO-1), and increases oxidized proteins in cortical and hippocampal neurons. Upon MCAO-induced stroke, neuronal Pnn-deficient mice show increased cerebral infarct area and elevated pro-apoptotic protein expression, establishing Pnn's neuroprotective role against ischemia-reperfusion injury through SRSF1/SRSF2 splicing regulation.\",\n      \"method\": \"Inducible conditional knockout, MCAO stroke model, Western blot, immunofluorescence, ROS measurement\",\n      \"journal\": \"Antioxidants (Basel, Switzerland)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockout with defined molecular (SRSF1/2 imbalance, oxidative stress markers) and functional (infarct area) phenotype; single lab\",\n      \"pmids\": [\"35326115\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Sequence analysis identified that MEMA/PNN protein contains three coiled-coil domains and one glycine loop domain, and is identical to a 160 kDa nuclear 'domain rich in serines' (DRS) protein that occurs free in the nucleoplasm and in U2-ribonucleoprotein structures, establishing its presence in RNA-associated nuclear complexes.\",\n      \"method\": \"Subtractive hybridization, sequence analysis, expression analysis\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — computational sequence analysis and expression; no direct functional experiment on the protein\",\n      \"pmids\": [\"10095061\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In primary cultured neurons and astrocytes subjected to oxygen-glucose deprivation (OGD), Pnn expression increases during OGD and decreases during reoxygenation in neurons, while in astrocytes Pnn expression decreases with OGD and increases during reoxygenation. Cytoplasmic translocation of Pnn (normally nuclear speckle-localized) is observed in neurons under OGD/reoxygenation but not in astrocytes, demonstrating cell-type-specific redistribution under ischemic stress.\",\n      \"method\": \"OGD model, MCAO mouse model, immunofluorescence, Western blot, primary cell culture\",\n      \"journal\": \"Brain sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct subcellular localization experiment in multiple cell types with ischemic stress model, functional implication of nuclear-cytoplasmic shift; single lab\",\n      \"pmids\": [\"33027948\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PNN (pinin/DRS/memA) is a multifunctional nuclear speckle-associated phosphoprotein that acts at the interface of transcription and mRNA processing: it binds spliced mRNPs near exon-exon junctions via interaction with RNPS1 to facilitate mRNA export, interacts with SR-rich splicing factors (SRp75, SRm300, ESRP1, SRSF1) to regulate alternative splicing of specific epithelial gene subsets (including apoptosis regulators Bcl-x and ICAD), and modulates transcription by binding the corepressor CtBP1 to relieve repression of the E-cadherin promoter while also coupling CtBP-mediated transcriptional regulation to mRNA splicing through RNA Pol II; at the cell periphery, PNN associates with desmosomes and its desmosomal localization promotes epithelial quiescence, while loss of PNN causes cell adhesion failure, epithelial-to-mesenchymal transition, apoptosis (through SRSF1-mediated Bcl-xS upregulation), and embryonic lethality in mice.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PNN (pinin/DRS/memA) is a nuclear speckle-associated phosphoprotein that operates at the interface of transcription, mRNA processing, and epithelial cell adhesion [#0, #3]. In the nucleus it associates preferentially with spliced mRNAs at positions immediately upstream of exon-exon junctions through direct interaction with the splicing/EJC factor RNPS1, and its suppression causes nuclear accumulation of poly(A)+ RNA, linking PNN to mRNA export [#0]. PNN assembles into multiprotein splicing complexes via its C-terminal RS-rich motif, interacting with SR-rich proteins (SRp75, SRm300, SRrp130) and with ESRP1 to regulate epithelial-type alternative splicing of defined gene subsets, including PAX6(5a), FOXJ3, and a class of long non-coding RNAs [#1, #8, #10]. PNN acts upstream of SRSF1 to control apoptotic splicing decisions: its depletion shifts Bcl-x toward the pro-apoptotic Bcl-xS isoform and alters ICAD splicing, driving apoptosis that is rescued by SRSF1 [#6]. Through interaction with the corepressor CtBP1, PNN relieves CtBP1-mediated repression of the E-cadherin promoter and is recruited to CtBP-associated chromatin, coupling transcriptional regulation to E-cadherin mRNA splicing via RNA polymerase II [#2, #4]. At the cell periphery, PNN localizes to desmosomes where it promotes stable cell-cell adhesion and epithelial quiescence; its loss downregulates E-cadherin and desmosomal proteins and causes adhesion failure, while overexpression hyperstabilizes adhesion and suppresses migration [#3, #5]. PNN is required for corneal epithelial identity and for pluripotency, and its homozygous knockout is embryonic lethal in mice [#6, #7, #9].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Established PNN as an mRNA-binding factor coupling splicing to export, answering whether it has a direct role in RNA metabolism rather than being merely speckle-resident.\",\n      \"evidence\": \"Co-IP, RNase H mapping, heterokaryon assay, overexpression and RNAi in human cells\",\n      \"pmids\": [\"14517304\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not define the RNA sequence/structure determinant of binding\", \"Mechanism of export coupling beyond RNPS1 interaction not resolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Showed PNN is a stable component of SR-rich splicing complexes in speckles, establishing the structural basis for its splicing role via its RS-rich motif.\",\n      \"evidence\": \"Yeast two-hybrid, co-IP, immunofluorescence co-localization\",\n      \"pmids\": [\"14578391\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"SRrp130 identity not molecularly defined\", \"Functional consequence of each interaction on specific transcripts not tested\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Linked PNN to transcriptional control by showing it antagonizes CtBP1 corepression at the E-cadherin promoter, connecting it to epithelial gene regulation.\",\n      \"evidence\": \"In vitro pull-down, co-IP, promoter reporter assays with gain/loss of function\",\n      \"pmids\": [\"15542832\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of PNN-CtBP1 interaction unknown\", \"Whether de-repression generalizes beyond E-cadherin untested here\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defined PNN as required for epithelial cell-cell adhesion, demonstrating that its nuclear/splicing functions translate to a junctional phenotype.\",\n      \"evidence\": \"shRNA knockdown with rescue control, immunofluorescence, Western blot in corneal epithelial cells\",\n      \"pmids\": [\"15735603\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not separate direct desmosomal role from indirect transcriptional/splicing effects\", \"Causal ordering of E-cadherin loss vs adhesion failure unresolved\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Resolved how PNN bridges transcription and splicing, showing CtBP recruits it to chromatin and that PNN and CtBP modulate E-cadherin splicing through RNA Pol II.\",\n      \"evidence\": \"ChIP, co-IP, reporter and splicing assays\",\n      \"pmids\": [\"18086895\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct chromatin-remodeling activity of PNN not biochemically defined\", \"Generality of Pol II coupling to other genes untested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Placed PNN upstream of SRSF1 in apoptotic splicing control and established its essentiality in development via embryonic lethality of knockout mice.\",\n      \"evidence\": \"RNAi, RT-PCR splicing analysis, SRSF1 overexpression rescue, flow cytometry, mouse knockout\",\n      \"pmids\": [\"22454513\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which PNN sustains SRSF1 levels not defined\", \"Cause of embryonic lethality not mapped to a specific splicing target\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed PNN is required in vivo for corneal/lens epithelial identity, linking its loss to Wnt/β-catenin activation and keratin switching.\",\n      \"evidence\": \"Pax6-Cre conditional knockout, histology, immunohistochemistry\",\n      \"pmids\": [\"19892877\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether β-catenin/Tcf4 activation is direct or downstream of adhesion loss unresolved\", \"p68 helicase misregulation mechanism unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified ESRP1 as a PNN partner and defined overlapping epithelial alternative-splicing programs, broadening the targets of PNN-dependent splicing.\",\n      \"evidence\": \"Reciprocal co-IP, deconvolution microscopy, transcriptome array with RT-PCR validation, shRNA\",\n      \"pmids\": [\"23299472\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct versus indirect splicing regulation for each target not distinguished\", \"Single cell-type context\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Extended PNN's splicing role to long non-coding RNAs, showing it shapes lncRNA exon usage in corneal epithelium.\",\n      \"evidence\": \"RNAi knockdown, RT-PCR, in situ hybridization, conditional knockout mouse\",\n      \"pmids\": [\"25489234\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequences of altered lncRNA isoforms unknown\", \"Mechanism of lncRNA target selection unresolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrated PNN is required for pluripotency and influences spliceosome assembly, via interaction with core spliceosomal proteins.\",\n      \"evidence\": \"Co-IP with SNRPA1/SNRPD1, RNAi, immunofluorescence, expression profiling in hiPSCs\",\n      \"pmids\": [\"28595116\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How PNN promotes spliceosome assembly mechanistically not defined\", \"Direct vs indirect effect on pluripotency factors untested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Revealed cell-type-specific PNN redistribution under ischemic stress, with nuclear-to-cytoplasmic translocation in neurons but not astrocytes.\",\n      \"evidence\": \"OGD and MCAO models, immunofluorescence, Western blot in primary cells\",\n      \"pmids\": [\"33027948\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional role of cytoplasmic PNN under stress not established\", \"Trigger for translocation unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Established a neuroprotective role for PNN against ischemia-reperfusion injury mediated through SRSF1/SRSF2 splicing balance and oxidative stress control.\",\n      \"evidence\": \"Inducible neuron-specific knockout, MCAO stroke model, Western blot, ROS measurement\",\n      \"pmids\": [\"35326115\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific splicing targets driving neuroprotection not identified\", \"Causal link between SRSF imbalance and oxidative damage not directly tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How PNN's distinct activities—mRNP export, alternative splicing, CtBP-coupled transcription, and desmosomal adhesion—are mechanistically coordinated and what governs its context-dependent localization remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of PNN domains in complex with partners\", \"No unifying mechanism linking nuclear and junctional pools\", \"Direct RNA-binding specificity not defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [2, 4]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0016607\", \"supporting_discovery_ids\": [1, 6, 13]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [12]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3, 5]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [13]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0, 6, 8, 10]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [2, 4]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [6, 11]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [7, 9]}\n    ],\n    \"complexes\": [\"nuclear speckle\", \"spliceosome\", \"exon-exon junction complex\", \"CtBP-associated chromatin complex\"],\n    \"partners\": [\"RNPS1\", \"CtBP1\", \"SRSF1\", \"ESRP1\", \"SRm300\", \"SRSF11\", \"SNRPA1\", \"SNRPD1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}