{"gene":"RNPC3","run_date":"2026-04-28T19:45:45","timeline":{"discoveries":[{"year":2003,"finding":"RNPC3 encodes a protein with two RNA recognition motif (RRM) domains and two bipartite nuclear targeting sequences; GFP-based localization demonstrated the protein resides in the cell nucleus.","method":"cDNA cloning, sequence analysis, GFP fusion localization imaging","journal":"Biochemical genetics","confidence":"Medium","confidence_rationale":"Tier 3 — single lab, direct GFP localization experiment with structural characterization but no functional mutagenesis","pmids":["14974681"],"is_preprint":false},{"year":2018,"finding":"RNPC3/65K is an essential component of the U12-dependent (minor) spliceosome in mammals; conditional knockout in adult mice caused increased U12-type intron retention in intestinal epithelial cells, accompanied by loss of phospho-ERK1/2 in intestinal crypt stem/progenitor cells, degeneration of gastrointestinal epithelium (increased apoptosis, reduced proliferation), leukopenia, and rapid weight loss. Homozygous germline loss was lethal prior to blastocyst implantation.","method":"Conditional Cre-lox mouse knockout, RT-PCR for intron retention, immunofluorescence/western blot for phospho-ERK1/2","journal":"RNA (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 2 — clean conditional KO mouse model with defined cellular phenotype (intron retention, apoptosis, proliferation defect) confirmed by multiple orthogonal methods","pmids":["30254136"],"is_preprint":false},{"year":2021,"finding":"RNPC3 is expressed in the developing forebrain, hypothalamus, and Rathke's pouch (pituitary anlage) in both mouse and human embryos; CRISPR/Cas9-generated mice carrying the pathogenic p.Leu483Phe variant in the RRM2 domain showed reduced pituitary GH content, establishing a direct role for RNPC3 in pituitary development.","method":"In situ hybridization (murine and human embryonic sections), CRISPR/Cas9 knock-in mice, hormone content measurement","journal":"Genetics in medicine","confidence":"Medium","confidence_rationale":"Tier 2 — CRISPR knock-in mouse with defined endocrine phenotype and expression mapping, single study","pmids":["34906446"],"is_preprint":false},{"year":2024,"finding":"The minor spliceosomal 65K/RNPC3 protein interacts with ANKRD11 (a cofactor of HDAC3); ANKRD11 bridges RNPC3 and HDAC3 on chromatin (shown by CUT&Tag), and this interaction is required for H3K9 and H4K5 deacetylation. Knockdown of ANKRD11 simultaneously reduced chromatin co-occupancy of HDAC3 and RNPC3 and decreased H3K9 deacetylation, linking the minor spliceosome to transcriptional regulation via histone deacetylation.","method":"Affinity purification (Drosophila lysates), CRISPR/Cas9 deletion strains, CUT&Tag chromatin-binding assays, RNAi knockdown, histone modification analysis","journal":"Advanced science","confidence":"High","confidence_rationale":"Tier 1-2 — interaction validated by affinity purification and CUT&Tag in two organisms, with genetic deletion and KD phenotypes; multiple orthogonal methods in a single study","pmids":["38837887"],"is_preprint":false},{"year":2025,"finding":"Conditional ablation of RNPC3 in activated B cells impaired germinal center (GC) B cell responses and antibody generation; RNPC3 deficiency inhibited proliferation and promoted apoptosis of activated B cells by failing to remove minor introns from minor intron-containing genes associated with cell proliferation and apoptosis, demonstrating a minor spliceosome-dependent role for RNPC3 in GC B cell development.","method":"Conditional B cell-specific Cre knockout mice, flow cytometry for GC B cell populations, RT-PCR/sequencing for minor intron retention, antibody titer measurement","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — conditional KO with defined cellular and molecular phenotype (intron retention, proliferation, apoptosis) confirmed by multiple assays","pmids":["40170400"],"is_preprint":false},{"year":2024,"finding":"RNPC3 acts as a molecular bridge promoting U11/U12 RNP complex formation, as referenced in the context of anti-RNPC3 autoantibodies in systemic sclerosis/MCTD.","method":"Autoantibody clinical association study (mechanistic description cited from prior work)","journal":"ACR open rheumatology","confidence":"Low","confidence_rationale":"Tier 4 — mechanistic claim cited without primary experimental data in this paper","pmids":["41946577"],"is_preprint":false}],"current_model":"RNPC3 encodes the U11/U12-65K protein, an essential component of the minor (U12-dependent) spliceosome that stabilizes the U11/U12 di-snRNP complex and is required for removal of U12-type introns from a subset of genes; beyond splicing, RNPC3 interacts with ANKRD11 to associate with HDAC3 on chromatin and promote H3K9/H4K5 deacetylation, thereby coupling minor spliceosome function to transcriptional regulation, and its loss in specific cell types (intestinal epithelium, GC B cells, pituitary) causes defects in proliferation and survival through failure to splice minor intron-containing genes."},"narrative":{"teleology":[{"year":2003,"claim":"Initial cloning established that RNPC3 encodes a nuclear protein with two RRM domains and bipartite nuclear localization signals, providing the structural basis for its later assignment to RNA-containing spliceosomal complexes.","evidence":"cDNA cloning, sequence analysis, and GFP-fusion imaging in cultured cells","pmids":["14974681"],"confidence":"Medium","gaps":["No functional assay performed; RRM domains not tested for RNA binding specificity","Nuclear localization shown only by overexpressed GFP fusion, not endogenous protein"]},{"year":2018,"claim":"Conditional knockout in mice demonstrated that RNPC3 is essential for U12-type intron removal in vivo; its loss caused widespread intron retention, loss of phospho-ERK1/2 in intestinal crypt cells, epithelial degeneration, and pre-implantation embryonic lethality, establishing RNPC3 as indispensable for proliferating tissues.","evidence":"Cre-lox conditional and germline knockout mice; RT-PCR intron retention assays; immunofluorescence and western blot for phospho-ERK1/2","pmids":["30254136"],"confidence":"High","gaps":["Mechanism by which U12-type intron retention leads to ERK1/2 signaling loss not resolved","Relative contribution of individual minor intron-containing genes to the phenotype unknown"]},{"year":2021,"claim":"Expression mapping and CRISPR knock-in of a patient-derived RRM2 missense variant (p.Leu483Phe) showed RNPC3 is required for pituitary development and growth hormone production, extending its essential role to endocrine organogenesis.","evidence":"In situ hybridization on mouse and human embryos; CRISPR/Cas9 knock-in mice with hormone content measurement","pmids":["34906446"],"confidence":"Medium","gaps":["Splicing targets affected by the Leu483Phe variant in pituitary cells not identified","Whether the GH deficit reflects a cell-autonomous spliceosome defect versus a developmental patterning defect is unresolved"]},{"year":2024,"claim":"Discovery that RNPC3 associates with ANKRD11 and HDAC3 on chromatin to drive H3K9/H4K5 deacetylation revealed an unexpected non-splicing function, coupling the minor spliceosome to epigenetic transcriptional regulation.","evidence":"Affinity purification from Drosophila lysates, CUT&Tag chromatin profiling, RNAi knockdown, histone modification analysis; confirmed across Drosophila and mammalian systems","pmids":["38837887"],"confidence":"High","gaps":["Whether RNPC3's chromatin role is independent of ongoing minor splicing or mechanistically linked remains unclear","Target genes regulated through the RNPC3–ANKRD11–HDAC3 axis not systematically defined","Structural basis of the RNPC3–ANKRD11 interaction not determined"]},{"year":2025,"claim":"B cell-specific ablation showed RNPC3 is required for germinal center responses and antibody production by ensuring minor intron splicing in proliferation and apoptosis genes, generalizing its essential role to adaptive immunity.","evidence":"Conditional B cell-specific Cre knockout mice; flow cytometry for GC B cells; RT-PCR/sequencing for intron retention; serum antibody titers","pmids":["40170400"],"confidence":"High","gaps":["Identity of the critical minor intron-containing transcripts whose mis-splicing drives GC B cell failure not fully delineated","Whether RNPC3's chromatin/HDAC3-associated function contributes to the B cell phenotype is untested"]},{"year":null,"claim":"It remains unknown how RNPC3's splicing and chromatin-regulatory functions are coordinated, which specific minor intron-containing transcripts are the critical effectors in each tissue, and whether the RNPC3–ANKRD11–HDAC3 axis operates independently of U12-type intron splicing.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of RNPC3 in the U11/U12 di-snRNP context","Genome-wide identification of direct RNPC3 chromatin targets in mammalian cells lacking","Separation-of-function alleles distinguishing splicing from chromatin roles not generated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[0,1]},{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[3]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,3]},{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[1,4]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[3]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[4]}],"complexes":["U11/U12 di-snRNP"],"partners":["ANKRD11","HDAC3"],"other_free_text":[]},"mechanistic_narrative":"RNPC3 encodes the 65K protein of the minor (U12-dependent) spliceosome, functioning as a dual-RRM domain RNA-binding protein that bridges U11/U12 di-snRNP complex formation and is essential for removal of U12-type introns from a subset of mammalian genes [PMID:14974681, PMID:30254136]. Conditional loss of RNPC3 in intestinal epithelium, germinal center B cells, and pituitary causes U12-type intron retention in proliferation- and survival-related transcripts, leading to impaired cell proliferation, increased apoptosis, and tissue degeneration, with homozygous germline deletion being pre-implantation lethal [PMID:30254136, PMID:40170400, PMID:34906446]. Beyond splicing, RNPC3 interacts with ANKRD11, which bridges it to HDAC3 on chromatin; this tripartite association promotes H3K9 and H4K5 deacetylation, coupling minor spliceosome components to transcriptional regulation via histone modification [PMID:38837887]. A pathogenic missense variant (p.Leu483Phe) in the RRM2 domain reduces pituitary growth hormone content in knock-in mice, establishing RNPC3 as a determinant of pituitary development [PMID:34906446]."},"prefetch_data":{"uniprot":{"accession":"Q96LT9","full_name":"RNA-binding region-containing protein 3","aliases":["RNA-binding motif protein 40","RNA-binding protein 40","U11/U12 small nuclear ribonucleoprotein 65 kDa protein","U11/U12 snRNP 65 kDa protein","U11/U12-65K"],"length_aa":517,"mass_kda":58.6,"function":"Participates in pre-mRNA U12-dependent splicing, performed by the minor spliceosome which removes U12-type introns. U12-type introns comprises less than 1% of all non-coding sequences. Binds to the 3'-stem-loop of m(7)G-capped U12 snRNA","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q96LT9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/RNPC3","classification":"Common Essential","n_dependent_lines":1207,"n_total_lines":1208,"dependency_fraction":0.9991721854304636},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"SF3B1","stoichiometry":0.2},{"gene":"SF3B2","stoichiometry":0.2},{"gene":"SF3B3","stoichiometry":0.2},{"gene":"SF3B6","stoichiometry":0.2},{"gene":"SNRPB","stoichiometry":0.2},{"gene":"SNRPD2","stoichiometry":0.2},{"gene":"SNRPF","stoichiometry":0.2},{"gene":"SNUPN","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/RNPC3","total_profiled":1310},"omim":[{"mim_id":"620204","title":"RNA, U12 SMALL NUCLEAR; RNU12","url":"https://www.omim.org/entry/620204"},{"mim_id":"618160","title":"PITUITARY HORMONE DEFICIENCY, COMBINED OR ISOLATED, 7; CPHD7","url":"https://www.omim.org/entry/618160"},{"mim_id":"618016","title":"RNA-BINDING REGION-CONTAINING PROTEIN 3; RNPC3","url":"https://www.omim.org/entry/618016"},{"mim_id":"613038","title":"PITUITARY HORMONE DEFICIENCY, COMBINED OR ISOLATED, 1; CPHD1","url":"https://www.omim.org/entry/613038"},{"mim_id":"607007","title":"SNAP-ASSOCIATED PROTEIN; SNAPIN","url":"https://www.omim.org/entry/607007"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/RNPC3"},"hgnc":{"alias_symbol":["KIAA1839","FLJ20008","RBM40","SNRNP65"],"prev_symbol":[]},"alphafold":{"accession":"Q96LT9","domains":[{"cath_id":"3.30.70.330","chopping":"29-106","consensus_level":"high","plddt":87.6355,"start":29,"end":106},{"cath_id":"-","chopping":"163-198","consensus_level":"medium","plddt":90.9961,"start":163,"end":198},{"cath_id":"3.30.70.330","chopping":"392-501","consensus_level":"high","plddt":92.0787,"start":392,"end":501}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96LT9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96LT9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96LT9-F1-predicted_aligned_error_v6.png","plddt_mean":67.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RNPC3","jax_strain_url":"https://www.jax.org/strain/search?query=RNPC3"},"sequence":{"accession":"Q96LT9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96LT9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96LT9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96LT9"}},"corpus_meta":[{"pmid":"32462814","id":"PMC_32462814","title":"Expanding the phenotype of biallelic RNPC3 variants associated with growth hormone deficiency.","date":"2020","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/32462814","citation_count":24,"is_preprint":false},{"pmid":"30254136","id":"PMC_30254136","title":"Early developmental arrest and impaired gastrointestinal homeostasis in U12-dependent splicing-defective Rnpc3-deficient mice.","date":"2018","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/30254136","citation_count":22,"is_preprint":false},{"pmid":"31885183","id":"PMC_31885183","title":"Identification of RNPC3 as a novel JAK2 fusion partner gene in B-acute lymphoblastic leukemia refractory to combination therapy including ruxolitinib.","date":"2019","source":"Molecular genetics & genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/31885183","citation_count":11,"is_preprint":false},{"pmid":"34906446","id":"PMC_34906446","title":"Pathogenic variants in RNPC3 are associated with hypopituitarism and primary ovarian insufficiency.","date":"2021","source":"Genetics in medicine : official journal of the American College of Medical Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/34906446","citation_count":10,"is_preprint":false},{"pmid":"38837887","id":"PMC_38837887","title":"Minor Spliceosomal 65K/RNPC3 Interacts with ANKRD11 and Mediates HDAC3-Regulated Histone Deacetylation and Transcription.","date":"2024","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/38837887","citation_count":7,"is_preprint":false},{"pmid":"14974681","id":"PMC_14974681","title":"Cloning and identification of a novel human RNPC3 gene that encodes a protein with two RRM domains and is expressed in the cell nucleus.","date":"2003","source":"Biochemical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/14974681","citation_count":7,"is_preprint":false},{"pmid":"33650182","id":"PMC_33650182","title":"Establishing intellectual disability as the key feature of patients with biallelic RNPC3 variants.","date":"2021","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/33650182","citation_count":6,"is_preprint":false},{"pmid":"37463572","id":"PMC_37463572","title":"A Novel RNPC3 Gene Variant Expands the Phenotype in Patients with Congenital Hypopituitarism and Neuropathy.","date":"2023","source":"Hormone research in paediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/37463572","citation_count":3,"is_preprint":false},{"pmid":"40170400","id":"PMC_40170400","title":"Minor Splicing Factor RNPC3 Is Essential for the Germinal Center B Cell Response.","date":"2025","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/40170400","citation_count":2,"is_preprint":false},{"pmid":"41946577","id":"PMC_41946577","title":"Clinical Associations of Anti-RNPC3 Autoantibodies in Mixed Connective Tissue Disease.","date":"2026","source":"ACR open rheumatology","url":"https://pubmed.ncbi.nlm.nih.gov/41946577","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.09.26.678859","title":"Unveiling The Origin of Human High-Grade Serous “Ovarian” Cancer Using Bulk and Single-Nucleus RNA Sequencing","date":"2025-09-30","source":"bioRxiv","url":"https://doi.org/10.1101/2025.09.26.678859","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.10.23.24315723","title":"Pathogenicity evaluation of coding germline variants identifies rare alleles enriched in hematological patients of a founder population","date":"2024-10-23","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.23.24315723","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7979,"output_tokens":1628,"usd":0.024178},"stage2":{"model":"claude-opus-4-6","input_tokens":4864,"output_tokens":1926,"usd":0.108705},"total_usd":0.132883,"stage1_batch_id":"msgbatch_01SUR8NDzVrNmyszWyJeCct7","stage2_batch_id":"msgbatch_01G7Yfutko3cDWzejrwH5AMx","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"RNPC3 encodes a protein with two RNA recognition motif (RRM) domains and two bipartite nuclear targeting sequences; GFP-based localization demonstrated the protein resides in the cell nucleus.\",\n      \"method\": \"cDNA cloning, sequence analysis, GFP fusion localization imaging\",\n      \"journal\": \"Biochemical genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab, direct GFP localization experiment with structural characterization but no functional mutagenesis\",\n      \"pmids\": [\"14974681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"RNPC3/65K is an essential component of the U12-dependent (minor) spliceosome in mammals; conditional knockout in adult mice caused increased U12-type intron retention in intestinal epithelial cells, accompanied by loss of phospho-ERK1/2 in intestinal crypt stem/progenitor cells, degeneration of gastrointestinal epithelium (increased apoptosis, reduced proliferation), leukopenia, and rapid weight loss. Homozygous germline loss was lethal prior to blastocyst implantation.\",\n      \"method\": \"Conditional Cre-lox mouse knockout, RT-PCR for intron retention, immunofluorescence/western blot for phospho-ERK1/2\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean conditional KO mouse model with defined cellular phenotype (intron retention, apoptosis, proliferation defect) confirmed by multiple orthogonal methods\",\n      \"pmids\": [\"30254136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"RNPC3 is expressed in the developing forebrain, hypothalamus, and Rathke's pouch (pituitary anlage) in both mouse and human embryos; CRISPR/Cas9-generated mice carrying the pathogenic p.Leu483Phe variant in the RRM2 domain showed reduced pituitary GH content, establishing a direct role for RNPC3 in pituitary development.\",\n      \"method\": \"In situ hybridization (murine and human embryonic sections), CRISPR/Cas9 knock-in mice, hormone content measurement\",\n      \"journal\": \"Genetics in medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — CRISPR knock-in mouse with defined endocrine phenotype and expression mapping, single study\",\n      \"pmids\": [\"34906446\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The minor spliceosomal 65K/RNPC3 protein interacts with ANKRD11 (a cofactor of HDAC3); ANKRD11 bridges RNPC3 and HDAC3 on chromatin (shown by CUT&Tag), and this interaction is required for H3K9 and H4K5 deacetylation. Knockdown of ANKRD11 simultaneously reduced chromatin co-occupancy of HDAC3 and RNPC3 and decreased H3K9 deacetylation, linking the minor spliceosome to transcriptional regulation via histone deacetylation.\",\n      \"method\": \"Affinity purification (Drosophila lysates), CRISPR/Cas9 deletion strains, CUT&Tag chromatin-binding assays, RNAi knockdown, histone modification analysis\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — interaction validated by affinity purification and CUT&Tag in two organisms, with genetic deletion and KD phenotypes; multiple orthogonal methods in a single study\",\n      \"pmids\": [\"38837887\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Conditional ablation of RNPC3 in activated B cells impaired germinal center (GC) B cell responses and antibody generation; RNPC3 deficiency inhibited proliferation and promoted apoptosis of activated B cells by failing to remove minor introns from minor intron-containing genes associated with cell proliferation and apoptosis, demonstrating a minor spliceosome-dependent role for RNPC3 in GC B cell development.\",\n      \"method\": \"Conditional B cell-specific Cre knockout mice, flow cytometry for GC B cell populations, RT-PCR/sequencing for minor intron retention, antibody titer measurement\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — conditional KO with defined cellular and molecular phenotype (intron retention, proliferation, apoptosis) confirmed by multiple assays\",\n      \"pmids\": [\"40170400\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"RNPC3 acts as a molecular bridge promoting U11/U12 RNP complex formation, as referenced in the context of anti-RNPC3 autoantibodies in systemic sclerosis/MCTD.\",\n      \"method\": \"Autoantibody clinical association study (mechanistic description cited from prior work)\",\n      \"journal\": \"ACR open rheumatology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — mechanistic claim cited without primary experimental data in this paper\",\n      \"pmids\": [\"41946577\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RNPC3 encodes the U11/U12-65K protein, an essential component of the minor (U12-dependent) spliceosome that stabilizes the U11/U12 di-snRNP complex and is required for removal of U12-type introns from a subset of genes; beyond splicing, RNPC3 interacts with ANKRD11 to associate with HDAC3 on chromatin and promote H3K9/H4K5 deacetylation, thereby coupling minor spliceosome function to transcriptional regulation, and its loss in specific cell types (intestinal epithelium, GC B cells, pituitary) causes defects in proliferation and survival through failure to splice minor intron-containing genes.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"RNPC3 encodes the 65K protein of the minor (U12-dependent) spliceosome, functioning as a dual-RRM domain RNA-binding protein that bridges U11/U12 di-snRNP complex formation and is essential for removal of U12-type introns from a subset of mammalian genes [PMID:14974681, PMID:30254136]. Conditional loss of RNPC3 in intestinal epithelium, germinal center B cells, and pituitary causes U12-type intron retention in proliferation- and survival-related transcripts, leading to impaired cell proliferation, increased apoptosis, and tissue degeneration, with homozygous germline deletion being pre-implantation lethal [PMID:30254136, PMID:40170400, PMID:34906446]. Beyond splicing, RNPC3 interacts with ANKRD11, which bridges it to HDAC3 on chromatin; this tripartite association promotes H3K9 and H4K5 deacetylation, coupling minor spliceosome components to transcriptional regulation via histone modification [PMID:38837887]. A pathogenic missense variant (p.Leu483Phe) in the RRM2 domain reduces pituitary growth hormone content in knock-in mice, establishing RNPC3 as a determinant of pituitary development [PMID:34906446].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Initial cloning established that RNPC3 encodes a nuclear protein with two RRM domains and bipartite nuclear localization signals, providing the structural basis for its later assignment to RNA-containing spliceosomal complexes.\",\n      \"evidence\": \"cDNA cloning, sequence analysis, and GFP-fusion imaging in cultured cells\",\n      \"pmids\": [\"14974681\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No functional assay performed; RRM domains not tested for RNA binding specificity\",\n        \"Nuclear localization shown only by overexpressed GFP fusion, not endogenous protein\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Conditional knockout in mice demonstrated that RNPC3 is essential for U12-type intron removal in vivo; its loss caused widespread intron retention, loss of phospho-ERK1/2 in intestinal crypt cells, epithelial degeneration, and pre-implantation embryonic lethality, establishing RNPC3 as indispensable for proliferating tissues.\",\n      \"evidence\": \"Cre-lox conditional and germline knockout mice; RT-PCR intron retention assays; immunofluorescence and western blot for phospho-ERK1/2\",\n      \"pmids\": [\"30254136\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which U12-type intron retention leads to ERK1/2 signaling loss not resolved\",\n        \"Relative contribution of individual minor intron-containing genes to the phenotype unknown\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Expression mapping and CRISPR knock-in of a patient-derived RRM2 missense variant (p.Leu483Phe) showed RNPC3 is required for pituitary development and growth hormone production, extending its essential role to endocrine organogenesis.\",\n      \"evidence\": \"In situ hybridization on mouse and human embryos; CRISPR/Cas9 knock-in mice with hormone content measurement\",\n      \"pmids\": [\"34906446\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Splicing targets affected by the Leu483Phe variant in pituitary cells not identified\",\n        \"Whether the GH deficit reflects a cell-autonomous spliceosome defect versus a developmental patterning defect is unresolved\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Discovery that RNPC3 associates with ANKRD11 and HDAC3 on chromatin to drive H3K9/H4K5 deacetylation revealed an unexpected non-splicing function, coupling the minor spliceosome to epigenetic transcriptional regulation.\",\n      \"evidence\": \"Affinity purification from Drosophila lysates, CUT&Tag chromatin profiling, RNAi knockdown, histone modification analysis; confirmed across Drosophila and mammalian systems\",\n      \"pmids\": [\"38837887\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether RNPC3's chromatin role is independent of ongoing minor splicing or mechanistically linked remains unclear\",\n        \"Target genes regulated through the RNPC3–ANKRD11–HDAC3 axis not systematically defined\",\n        \"Structural basis of the RNPC3–ANKRD11 interaction not determined\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"B cell-specific ablation showed RNPC3 is required for germinal center responses and antibody production by ensuring minor intron splicing in proliferation and apoptosis genes, generalizing its essential role to adaptive immunity.\",\n      \"evidence\": \"Conditional B cell-specific Cre knockout mice; flow cytometry for GC B cells; RT-PCR/sequencing for intron retention; serum antibody titers\",\n      \"pmids\": [\"40170400\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Identity of the critical minor intron-containing transcripts whose mis-splicing drives GC B cell failure not fully delineated\",\n        \"Whether RNPC3's chromatin/HDAC3-associated function contributes to the B cell phenotype is untested\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown how RNPC3's splicing and chromatin-regulatory functions are coordinated, which specific minor intron-containing transcripts are the critical effectors in each tissue, and whether the RNPC3–ANKRD11–HDAC3 axis operates independently of U12-type intron splicing.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model of RNPC3 in the U11/U12 di-snRNP context\",\n        \"Genome-wide identification of direct RNPC3 chromatin targets in mammalian cells lacking\",\n        \"Separation-of-function alleles distinguishing splicing from chromatin roles not generated\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [1, 4]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"complexes\": [\n      \"U11/U12 di-snRNP\"\n    ],\n    \"partners\": [\n      \"ANKRD11\",\n      \"HDAC3\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}