{"gene":"POLR3B","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":2007,"finding":"A splice-site mutation in zebrafish polr3b (slim jim mutant) causes deletion of 41 conserved amino acids from the Polr3b protein, impairing its interaction with Polr3k (Rpc11 ortholog). Reconstitution in S. pombe showed that the comparable rpc2 deletion leads to markedly reduced levels of Rpc11p in the recovered Pol III complex. Overexpression of zebrafish polr3k rescued exocrine defects, establishing that the phenotype is due to Rpc11 deficiency caused by the Polr3b structural disruption.","method":"Genetic mutant characterization (zebrafish), S. pombe engineering with comparable deletion, Pol III complex purification, rescue by polr3k cDNA overexpression","journal":"PLoS biology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vivo genetic rescue combined with biochemical reconstitution in S. pombe showing reduced Rpc11 in the complex; multiple orthogonal methods in one study","pmids":["18044988"],"is_preprint":false},{"year":2011,"finding":"POLR3B (RPC2) encodes the second largest subunit of RNA Polymerase III; together with POLR3A (RPC1) it forms the active center of the polymerase and contributes to catalytic activity. A splice-site mutation in POLR3B was shown by RT-PCR to cause deletion of exon 18 from the mRNA, and a nonsense mutation underwent nonsense-mediated mRNA decay, confirming loss-of-function as the disease mechanism.","method":"Whole-exome sequencing, RT-PCR and sequencing of splice-site mutation product, NMD demonstration","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct molecular characterization of transcript consequences with two orthogonal methods (RT-PCR, NMD demonstration); single study","pmids":["22036171"],"is_preprint":false},{"year":2019,"finding":"The POLR3B R103H missense mutation severely impairs assembly of the Pol III complex, as demonstrated by proteomics in human cells. Homozygosity for this mutation is embryonically lethal in mice (no homozygotes detected at E9.5), indicating that R103H is a severe hypomorphic allele that disrupts Pol III biogenesis.","method":"Proteomics (mass spectrometry) in human cell line expressing R103H; mouse genetics (embryonic lethality)","journal":"Molecular brain","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — proteomics directly measuring complex assembly defect combined with in vivo mouse lethality phenotype; multiple orthogonal methods in one study","pmids":["31221184"],"is_preprint":false},{"year":2021,"finding":"De novo heterozygous missense variants in POLR3B cause aberrant association of individual Pol III enzyme subunits rather than affecting overall enzyme assembly or stability, a distinct pathogenic mechanism from the biallelic loss-of-function variants that disrupt overall complex assembly.","method":"Protein modeling and proteomic analysis of patient-derived cells with de novo POLR3B variants","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — proteomics and structural modeling in patient cells; single lab, two complementary methods","pmids":["33417887"],"is_preprint":false},{"year":2022,"finding":"A mass spectrometry-based assay characterized Pol III assembly stages and demonstrated that the R103H substitution in POLR3B causes specific assembly defects. The PAQosome (HSP90 co-chaperone complex) participates in Pol III biogenesis. Riluzole partially corrects the R103H-driven assembly defects.","method":"Mass spectrometry-based Pol III assembly assay, PAQosome interaction analysis, drug (riluzole) treatment in cells","journal":"Molecular brain","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro/cell-based assembly assay with direct biochemical readout, PAQosome functional dissection, and pharmacological correction; multiple orthogonal methods in one study","pmids":["36451185"],"is_preprint":false},{"year":2023,"finding":"The POLR3B Δ10 mutation (deletion of 10 amino acids) causes a Pol III assembly defect, as shown by affinity purification-mass spectrometry, and reduces POLR3BΔ10 protein levels in both cytoplasm and nucleus (western blot). In mice with postnatal oligodendrocyte-specific expression of the Δ10 mutant, defective oligodendrocyte precursor proliferation and differentiation results in failure to produce adequate mature oligodendrocytes during postnatal myelinogenesis, causing severe hypomyelination.","method":"Affinity purification–mass spectrometry (proteomics), western blot (subcellular fractionation), conditional mouse model with lineage tracing, immunofluorescence, immunohistochemistry, spectral confocal reflectance microscopy","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — proteomics for assembly defect, in vivo mouse model with lineage tracing defining the cellular mechanism, multiple orthogonal methods","pmids":["37635302"],"is_preprint":false},{"year":2016,"finding":"Intestinal epithelium-specific hypomorphic mutation of Polr3b (via VillinCre) in mice causes reduced proliferation, abnormal epithelial architecture, loss of Wnt signaling, and dramatic increase in apoptotic cells in crypts, demonstrating that Polr3b is required for intestinal crypt maintenance during early postnatal development. Lineage tracing showed that Polr3b-deficient crypts are replaced by wild-type escapers.","method":"Conditional mouse knockout (VillinCre), histology, genetic lineage tracing (Rosa26-lox-stop-lox-YFP), enteroid culture, molecular analysis","journal":"Cellular and molecular gastroenterology and hepatology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean tissue-specific KO with defined proliferation/apoptosis/Wnt signaling phenotype and lineage tracing; multiple orthogonal methods","pmids":["28090567"],"is_preprint":false},{"year":2022,"finding":"The HLD8-associated nonsense mutation R550X in POLR3B causes the mutant protein to localize as aggregates in lysosomes (not in the nucleus as wild-type), decreases lysosome-related mTOR signaling, and inhibits oligodendroglial precursor cell morphological differentiation. Ibuprofen (NSAID) reversed the differentiation defect and improved mTOR signaling.","method":"Overexpression of wild-type vs. R550X POLR3B in FBD-102b oligodendroglial precursor cell line; immunofluorescence localization, mTOR signaling assay, morphological differentiation assay, ibuprofen treatment","journal":"Neurology international","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — cell-based overexpression with multiple readouts (localization, signaling, differentiation) but single lab and no in vivo confirmation","pmids":["35225888"],"is_preprint":false},{"year":2012,"finding":"INMAP, a truncated isoform of POLR3B, localizes to the nucleus in a punctate pattern dependent on its 209–290 amino acid region, and overexpression of INMAP inhibits the transcriptional activities of p53 and AP-1 in a dose-dependent manner.","method":"Deletion analysis with subcellular localization (immunofluorescence), luciferase transcriptional reporter assays for p53 and AP-1 activity","journal":"Molecular and cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct reporter assays and localization mapping; single lab, overexpression-based, limited mechanistic depth","pmids":["23124897"],"is_preprint":false},{"year":2024,"finding":"A POLR3B:c.1625A>G;p.(Asn542Ser) disease variant causes mis-splicing of POLR3B mRNA. In genome-edited HEK293 cells, this leads to decreased levels of multiple Pol III subunits and TFIIIB, but auto-upregulation of POLR3E (the Pol III termination-reinitiation subunit). La protein was increased relative to its pre-tRNA ligands. Transcription assays showed greater deficiency for tRNA genes with 4T terminators versus ≥5T terminators. La knockdown decreased Pol III ncRNA expression independently of RNA stability. Small-RNA sequencing showed increased tRNA fragments from pre-tRNA 3′-trailers (tRF-1) and elevated miRNAs, indicating that decreased Pol III output creates a functional excess of La protein that reshapes small ncRNA profiles.","method":"CRISPR genome editing (POLR3B HEK293 cells), RT-PCR (mis-splicing), western blot (subunit levels), cellular transcription assays, La protein knockdown, small-RNA sequencing (tRF and miRNA profiling), patient fibroblast analysis","journal":"bioRxiv (preprint)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genome-edited cell model with multiple orthogonal methods; preprint, not yet peer-reviewed","pmids":["38410490"],"is_preprint":true},{"year":2024,"finding":"Polr3b heterozygous (Polr3b+/-) mice show sexually dimorphic, organ-specific effects: female Polr3b+/- mice have improved bone health but compromised gut barrier function and susceptibility to dermatitis; male Polr3b+/- mice are lighter with improved gut barrier function in old age. Neither sex showed extended lifespan, indicating reduced Pol III activity does not extend mammalian lifespan.","method":"Mouse genetics (Polr3b+/- C57BL/6N), longitudinal phenotypic analysis of bone, gut barrier, metabolic parameters","journal":"Aging cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean genetic KO model with multiple organ-specific functional readouts; single lab, no molecular mechanism defined beyond reduced Pol III dosage","pmids":["38465473"],"is_preprint":false}],"current_model":"POLR3B (RPC2) encodes the second-largest catalytic subunit of RNA Polymerase III, forming the active center of the 17-subunit enzyme with POLR3A; it is essential for Pol III assembly (mediated in part by the PAQosome/HSP90 co-chaperone machinery), physically interacts with the Rpc11/POLR3K subunit to support RNA cleavage and polymerase recycling, and is required for Pol III transcription of tRNAs and other small non-coding RNAs — with loss-of-function causing defective oligodendrocyte precursor proliferation/differentiation (hypomyelination), intestinal crypt failure, and embryonic lethality at high severity, while dominant de novo missense variants cause aberrant subunit associations distinct from the assembly disruption seen with biallelic variants."},"narrative":{"mechanistic_narrative":"POLR3B (RPC2) encodes the second-largest catalytic subunit of RNA Polymerase III, which together with POLR3A forms the active center of the enzyme that transcribes tRNAs and other small non-coding RNAs [PMID:22036171]. Its structural integrity is required to recruit and retain the POLR3K/Rpc11 subunit within the polymerase; a deletion disrupting the Polr3b–Polr3k interface reduces Rpc11 in the assembled complex, and the resulting phenotype is rescued by restoring Rpc11 dosage [PMID:18044988]. Pol III biogenesis proceeds through defined assembly stages assisted by the PAQosome/HSP90 co-chaperone machinery, and biallelic loss-of-function or severe hypomorphic POLR3B variants (e.g. R103H, Δ10) block proper complex assembly, whereas dominant de novo missense variants instead cause aberrant association of individual subunits without globally destabilizing the enzyme — establishing two distinct pathogenic mechanisms [PMID:31221184, PMID:33417887, PMID:36451185, PMID:37635302]. POLR3B function is essential in vivo: homozygous R103H is embryonically lethal in mice [PMID:31221184], intestinal-specific hypomorphism causes crypt proliferation failure, Wnt-signaling loss and apoptosis [PMID:28090567], and oligodendrocyte-specific expression of assembly-defective POLR3B impairs oligodendrocyte precursor proliferation and differentiation, producing severe hypomyelination [PMID:37635302]. POLR3B variants cause hypomyelinating leukodystrophy through these mechanisms [PMID:37635302, PMID:35225888]. Reduced Pol III output also reshapes downstream small ncRNA profiles via a functional excess of La protein [PMID:38410490].","teleology":[{"year":2007,"claim":"Established that POLR3B's structural integrity is required to retain the Rpc11/POLR3K subunit in the Pol III complex, linking a specific protein–protein interface to enzyme function and phenotype.","evidence":"Zebrafish slim jim mutant characterization, comparable rpc2 deletion reconstituted in S. pombe with complex purification, and rescue by polr3k overexpression","pmids":["18044988"],"confidence":"High","gaps":["Does not define the atomic-resolution interface between POLR3B and POLR3K","Does not establish whether reduced Rpc11 affects RNA cleavage versus recycling in human cells"]},{"year":2011,"claim":"Defined POLR3B as the second-largest catalytic subunit contributing to the Pol III active center and established loss-of-function as a disease mechanism at the transcript level.","evidence":"Whole-exome sequencing of patients, RT-PCR of a splice-site product, and demonstration of nonsense-mediated decay","pmids":["22036171"],"confidence":"Medium","gaps":["Does not measure catalytic activity loss directly","Does not connect transcript loss to a specific cellular tRNA/ncRNA deficit"]},{"year":2016,"claim":"Showed POLR3B is required in a specific tissue context — intestinal crypt maintenance — connecting Pol III activity to proliferation, Wnt signaling and survival.","evidence":"VillinCre conditional hypomorphic mouse, histology, lineage tracing, enteroid culture","pmids":["28090567"],"confidence":"High","gaps":["Does not identify which Pol III transcripts mediate the crypt phenotype","Mechanism linking Pol III loss to Wnt signaling not defined"]},{"year":2019,"claim":"Demonstrated that the R103H missense allele acts by impairing Pol III complex assembly and is essential for embryonic viability, distinguishing assembly disruption as a quantifiable pathogenic readout.","evidence":"Proteomics in human cells expressing R103H plus mouse embryonic lethality genetics","pmids":["31221184"],"confidence":"High","gaps":["Does not define which assembly step is blocked","Does not link assembly defect to a specific transcriptional output"]},{"year":2021,"claim":"Distinguished dominant de novo missense variants — which cause aberrant subunit associations — from biallelic loss-of-function variants that disrupt overall assembly, defining two pathogenic mechanisms.","evidence":"Protein modeling and proteomics of patient-derived cells with de novo variants","pmids":["33417887"],"confidence":"Medium","gaps":["Functional consequence of aberrant subunit association on transcription not measured","Single-lab proteomic dataset"]},{"year":2022,"claim":"Resolved Pol III assembly into staged intermediates, implicated the PAQosome/HSP90 chaperone machinery in biogenesis, and showed pharmacological correction of an assembly defect.","evidence":"Mass spectrometry-based assembly assay, PAQosome interaction analysis, riluzole treatment in cells","pmids":["36451185"],"confidence":"High","gaps":["Mechanism of riluzole correction not defined","PAQosome dependence not tested in vivo"]},{"year":2022,"claim":"Proposed an alternative, localization-based mechanism in which the R550X nonsense product mislocalizes to lysosomes and depresses mTOR signaling to block oligodendroglial differentiation.","evidence":"Overexpression of WT vs R550X in FBD-102b oligodendroglial precursors, localization, mTOR assay, differentiation assay, ibuprofen rescue","pmids":["35225888"],"confidence":"Medium","gaps":["Overexpression-based, no in vivo confirmation","Relationship between lysosomal aggregation and loss of nuclear Pol III function not resolved","Single lab"]},{"year":2023,"claim":"Defined the cellular basis of hypomyelination by showing assembly-defective POLR3B impairs oligodendrocyte precursor proliferation and differentiation in vivo.","evidence":"AP-MS for assembly defect, subcellular western blot, conditional oligodendrocyte mouse model with lineage tracing and imaging","pmids":["37635302"],"confidence":"High","gaps":["Which Pol III transcripts limit OPC maturation not identified","Does not connect assembly defect to a molecular trigger of differentiation arrest"]},{"year":2024,"claim":"Showed that reduced Pol III output reshapes the small ncRNA landscape through a functional excess of La protein, linking subunit deficiency to altered tRNA fragment and miRNA profiles.","evidence":"CRISPR-edited HEK293 POLR3B cells, RT-PCR, western blot, transcription assays, La knockdown, small-RNA sequencing, patient fibroblasts (preprint)","pmids":["38410490"],"confidence":"Medium","gaps":["Preprint, not yet peer-reviewed","Causal contribution of altered ncRNA profiles to disease phenotype untested"]},{"year":2024,"claim":"Tested whether reduced Pol III dosage produces systemic or lifespan effects, revealing sexually dimorphic, organ-specific consequences without lifespan extension.","evidence":"Polr3b+/- mouse longitudinal phenotyping of bone, gut barrier and metabolic parameters","pmids":["38465473"],"confidence":"Medium","gaps":["No molecular mechanism defined beyond reduced dosage","Basis of sexual dimorphism unknown"]},{"year":null,"claim":"It remains unresolved which specific Pol III transcripts mediate the tissue-selective phenotypes (oligodendrocyte, crypt) and how assembly-stage defects translate into defined transcriptional deficits.","evidence":"No timeline discovery links a specific Pol III ncRNA deficit to the cellular phenotypes","pmids":[],"confidence":"Low","gaps":["No causal transcript identified for hypomyelination or crypt failure","No structural model of human POLR3B–POLR3K interface","Mechanistic reconciliation of nuclear assembly defect versus lysosomal mislocalization model lacking"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[0,1]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[1]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[5,8]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[5]},{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[7]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[9]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[2,4]}],"complexes":["RNA Polymerase III"],"partners":["POLR3A","POLR3K"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NW08","full_name":"DNA-directed RNA polymerase III subunit RPC2","aliases":["C128","DNA-directed RNA polymerase III 127.6 kDa polypeptide","DNA-directed RNA polymerase III subunit B"],"length_aa":1133,"mass_kda":127.8,"function":"Catalytic core component of RNA polymerase III (Pol III), a DNA-dependent RNA polymerase which synthesizes small non-coding RNAs using the four ribonucleoside triphosphates as substrates. Synthesizes 5S rRNA, snRNAs, tRNAs and miRNAs from at least 500 distinct genomic loci (PubMed:20413673, PubMed:33558766). Pol III-mediated transcription cycle proceeds through transcription initiation, transcription elongation and transcription termination stages. During transcription initiation, Pol III is recruited to DNA promoters type I, II or III with the help of general transcription factors and other specific initiation factors. Once the polymerase has escaped from the promoter it enters the elongation phase during which RNA is actively polymerized, based on complementarity with the template DNA strand. Transcription termination involves the release of the RNA transcript and polymerase from the DNA (PubMed:20413673, PubMed:33335104, PubMed:33558764, PubMed:33558766, PubMed:33674783, PubMed:34675218). Forms Pol III active center together with the largest subunit POLR3A/RPC1. A single-stranded DNA template strand of the promoter is positioned within the central active site cleft of Pol III. Appends one nucleotide at a time to the 3' end of the nascent RNA, with POLR3A/RPC1 contributing a Mg(2+)-coordinating DxDGD motif, and POLR3B/RPC2 participating in the coordination of a second Mg(2+) ion and providing lysine residues believed to facilitate Watson-Crick base pairing between the incoming nucleotide and template base. Typically, Mg(2+) ions direct a 5' nucleoside triphosphate to form a phosphodiester bond with the 3' hydroxyl of the preceding nucleotide of the nascent RNA, with the elimination of pyrophosphate (PubMed:19609254, PubMed:20413673, PubMed:33335104, PubMed:33558764, PubMed:33674783, PubMed:34675218). Pol III plays a key role in sensing and limiting infection by intracellular bacteria and DNA viruses. Acts as a nuclear and cytosolic DNA sensor involved in innate immune response. Can sense non-self dsDNA that serves as template for transcription into dsRNA. The non-self RNA polymerase III transcripts, such as Epstein-Barr virus-encoded RNAs (EBERs) induce type I interferon and NF-kappa-B through the RIG-I pathway","subcellular_location":"Nucleus; Cytoplasm, cytosol","url":"https://www.uniprot.org/uniprotkb/Q9NW08/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/POLR3B","classification":"Common Essential","n_dependent_lines":1202,"n_total_lines":1208,"dependency_fraction":0.9950331125827815},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000013503","cell_line_id":"CID000710","localizations":[{"compartment":"nuclear_punctae","grade":3},{"compartment":"nucleoplasm","grade":2}],"interactors":[{"gene":"POLR2E","stoichiometry":10.0},{"gene":"POLR2H","stoichiometry":10.0},{"gene":"POLR2K","stoichiometry":10.0},{"gene":"POLR3A","stoichiometry":10.0},{"gene":"TRMT1L","stoichiometry":10.0},{"gene":"POLR3E","stoichiometry":10.0},{"gene":"POLR3H","stoichiometry":10.0},{"gene":"POLR3F","stoichiometry":10.0},{"gene":"POLR3GL","stoichiometry":10.0},{"gene":"POLR3C","stoichiometry":10.0}],"url":"https://opencell.sf.czbiohub.org/target/CID000710","total_profiled":1310},"omim":[{"mim_id":"619742","title":"CHARCOT-MARIE-TOOTH DISEASE, DEMYELINATING, TYPE 1I; CMT1I","url":"https://www.omim.org/entry/619742"},{"mim_id":"616494","title":"LEUKODYSTROPHY, HYPOMYELINATING, 11; HLD11","url":"https://www.omim.org/entry/616494"},{"mim_id":"614381","title":"LEUKODYSTROPHY, HYPOMYELINATING, 8, WITH OR WITHOUT OLIGODONTIA AND/OR HYPOGONADOTROPIC HYPOGONADISM; HLD8","url":"https://www.omim.org/entry/614381"},{"mim_id":"614366","title":"POLYMERASE III, RNA, SUBUNIT B; POLR3B","url":"https://www.omim.org/entry/614366"},{"mim_id":"614258","title":"POLYMERASE III, RNA, SUBUNIT A; POLR3A","url":"https://www.omim.org/entry/614258"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nuclear speckles","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/POLR3B"},"hgnc":{"alias_symbol":["RPC2","FLJ10388","C128"],"prev_symbol":[]},"alphafold":{"accession":"Q9NW08","domains":[{"cath_id":"3.90.1100.10","chopping":"40-181_361-464_490-495","consensus_level":"high","plddt":89.3485,"start":40,"end":495},{"cath_id":"3.90.1110.10","chopping":"185-355","consensus_level":"medium","plddt":86.6927,"start":185,"end":355},{"cath_id":"3.90.1070.20","chopping":"501-663","consensus_level":"high","plddt":90.5926,"start":501,"end":663},{"cath_id":"2.40.270.10","chopping":"673-688_720-768_891-1010","consensus_level":"high","plddt":94.2743,"start":673,"end":1010},{"cath_id":"2.40.50.150","chopping":"774-836_850-888","consensus_level":"high","plddt":89.9553,"start":774,"end":888},{"cath_id":"3.90.1800.10","chopping":"1048-1119","consensus_level":"medium","plddt":93.3646,"start":1048,"end":1119}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NW08","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NW08-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NW08-F1-predicted_aligned_error_v6.png","plddt_mean":89.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=POLR3B","jax_strain_url":"https://www.jax.org/strain/search?query=POLR3B"},"sequence":{"accession":"Q9NW08","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NW08.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NW08/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NW08"}},"corpus_meta":[{"pmid":"25339210","id":"PMC_25339210","title":"Clinical 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without dental abnormalities and/or hypogonadotropic hypogonadism.","date":"2013","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23355746","citation_count":92,"is_preprint":false},{"pmid":"20126794","id":"PMC_20126794","title":"The DC gate in Channelrhodopsin-2: crucial hydrogen bonding interaction between C128 and D156.","date":"2010","source":"Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology","url":"https://pubmed.ncbi.nlm.nih.gov/20126794","citation_count":74,"is_preprint":false},{"pmid":"18044988","id":"PMC_18044988","title":"Mutation of RNA Pol III subunit rpc2/polr3b Leads to Deficiency of Subunit Rpc11 and disrupts zebrafish digestive development.","date":"2007","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/18044988","citation_count":61,"is_preprint":false},{"pmid":"27512013","id":"PMC_27512013","title":"Phenotypic spectrum of POLR3B 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phenotype.","date":"2020","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/32319736","citation_count":12,"is_preprint":false},{"pmid":"35482004","id":"PMC_35482004","title":"Novel de novo POLR3B mutations responsible for demyelinating Charcot-Marie-Tooth disease in Japan.","date":"2022","source":"Annals of clinical and translational neurology","url":"https://pubmed.ncbi.nlm.nih.gov/35482004","citation_count":10,"is_preprint":false},{"pmid":"39348199","id":"PMC_39348199","title":"POLR3B is associated with a developmental and epileptic encephalopathy with myoclonic-atonic seizures and ataxia.","date":"2024","source":"Epilepsia","url":"https://pubmed.ncbi.nlm.nih.gov/39348199","citation_count":9,"is_preprint":false},{"pmid":"37635302","id":"PMC_37635302","title":"Hypomyelination, hypodontia and craniofacial abnormalities in a Polr3b mouse model of leukodystrophy.","date":"2023","source":"Brain : a journal of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/37635302","citation_count":9,"is_preprint":false},{"pmid":"37197783","id":"PMC_37197783","title":"Craniofacial features of POLR3-related leukodystrophy caused by biallelic variants in POLR3A, POLR3B and POLR1C.","date":"2023","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/37197783","citation_count":9,"is_preprint":false},{"pmid":"34289880","id":"PMC_34289880","title":"Whole-exome sequencing reveals POLR3B variants associated with progeria-related Wiedemann-Rautenstrauch syndrome.","date":"2021","source":"Italian journal of pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/34289880","citation_count":9,"is_preprint":false},{"pmid":"36451185","id":"PMC_36451185","title":"Riluzole partially restores RNA polymerase III complex assembly in cells expressing the leukodystrophy-causative variant POLR3B R103H.","date":"2022","source":"Molecular brain","url":"https://pubmed.ncbi.nlm.nih.gov/36451185","citation_count":7,"is_preprint":false},{"pmid":"31577365","id":"PMC_31577365","title":"POLR3B-associated leukodystrophy: clinical, neuroimaging and molecular-genetic analyses in four patients: clinical heterogeneity and novel mutations in POLR3B gene.","date":"2019","source":"Neurologia i neurochirurgia polska","url":"https://pubmed.ncbi.nlm.nih.gov/31577365","citation_count":6,"is_preprint":false},{"pmid":"23124897","id":"PMC_23124897","title":"INMAP, a novel truncated version of POLR3B, represses AP-1 and p53 transcriptional activity.","date":"2012","source":"Molecular and cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23124897","citation_count":6,"is_preprint":false},{"pmid":"36650939","id":"PMC_36650939","title":"Identification of POLR3B biallelic mutations-associated hypomyelinating leukodystrophy-8 in two siblings.","date":"2023","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36650939","citation_count":4,"is_preprint":false},{"pmid":"35436926","id":"PMC_35436926","title":"Intellectual disability associated with craniofacial dysmorphism due to POLR3B mutation and defect in spliceosomal machinery.","date":"2022","source":"BMC medical genomics","url":"https://pubmed.ncbi.nlm.nih.gov/35436926","citation_count":4,"is_preprint":false},{"pmid":"36042647","id":"PMC_36042647","title":"Case report: Biallelic variants in POLR3B gene lead to 4H leukodystrophy from the study of brother and sister.","date":"2022","source":"Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36042647","citation_count":4,"is_preprint":false},{"pmid":"38465473","id":"PMC_38465473","title":"Polr3b heterozygosity in mice induces both beneficial and deleterious effects on health during ageing with no effect on lifespan.","date":"2024","source":"Aging cell","url":"https://pubmed.ncbi.nlm.nih.gov/38465473","citation_count":3,"is_preprint":false},{"pmid":"37554900","id":"PMC_37554900","title":"Uncertain significance mutation in the POLR3B gene in a Syrian boy with leukodystrophy: a case report.","date":"2023","source":"Annals of medicine and surgery (2012)","url":"https://pubmed.ncbi.nlm.nih.gov/37554900","citation_count":3,"is_preprint":false},{"pmid":"35434302","id":"PMC_35434302","title":"The First Korean Siblings With Adult-Onset 4H Leukodystrophy Related to Nonsynonymous POLR3B Mutations.","date":"2022","source":"Neurology. 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Reconstitution in S. pombe showed that the comparable rpc2 deletion leads to markedly reduced levels of Rpc11p in the recovered Pol III complex. Overexpression of zebrafish polr3k rescued exocrine defects, establishing that the phenotype is due to Rpc11 deficiency caused by the Polr3b structural disruption.\",\n      \"method\": \"Genetic mutant characterization (zebrafish), S. pombe engineering with comparable deletion, Pol III complex purification, rescue by polr3k cDNA overexpression\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vivo genetic rescue combined with biochemical reconstitution in S. pombe showing reduced Rpc11 in the complex; multiple orthogonal methods in one study\",\n      \"pmids\": [\"18044988\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"POLR3B (RPC2) encodes the second largest subunit of RNA Polymerase III; together with POLR3A (RPC1) it forms the active center of the polymerase and contributes to catalytic activity. A splice-site mutation in POLR3B was shown by RT-PCR to cause deletion of exon 18 from the mRNA, and a nonsense mutation underwent nonsense-mediated mRNA decay, confirming loss-of-function as the disease mechanism.\",\n      \"method\": \"Whole-exome sequencing, RT-PCR and sequencing of splice-site mutation product, NMD demonstration\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct molecular characterization of transcript consequences with two orthogonal methods (RT-PCR, NMD demonstration); single study\",\n      \"pmids\": [\"22036171\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The POLR3B R103H missense mutation severely impairs assembly of the Pol III complex, as demonstrated by proteomics in human cells. Homozygosity for this mutation is embryonically lethal in mice (no homozygotes detected at E9.5), indicating that R103H is a severe hypomorphic allele that disrupts Pol III biogenesis.\",\n      \"method\": \"Proteomics (mass spectrometry) in human cell line expressing R103H; mouse genetics (embryonic lethality)\",\n      \"journal\": \"Molecular brain\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — proteomics directly measuring complex assembly defect combined with in vivo mouse lethality phenotype; multiple orthogonal methods in one study\",\n      \"pmids\": [\"31221184\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"De novo heterozygous missense variants in POLR3B cause aberrant association of individual Pol III enzyme subunits rather than affecting overall enzyme assembly or stability, a distinct pathogenic mechanism from the biallelic loss-of-function variants that disrupt overall complex assembly.\",\n      \"method\": \"Protein modeling and proteomic analysis of patient-derived cells with de novo POLR3B variants\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — proteomics and structural modeling in patient cells; single lab, two complementary methods\",\n      \"pmids\": [\"33417887\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"A mass spectrometry-based assay characterized Pol III assembly stages and demonstrated that the R103H substitution in POLR3B causes specific assembly defects. The PAQosome (HSP90 co-chaperone complex) participates in Pol III biogenesis. Riluzole partially corrects the R103H-driven assembly defects.\",\n      \"method\": \"Mass spectrometry-based Pol III assembly assay, PAQosome interaction analysis, drug (riluzole) treatment in cells\",\n      \"journal\": \"Molecular brain\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro/cell-based assembly assay with direct biochemical readout, PAQosome functional dissection, and pharmacological correction; multiple orthogonal methods in one study\",\n      \"pmids\": [\"36451185\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The POLR3B Δ10 mutation (deletion of 10 amino acids) causes a Pol III assembly defect, as shown by affinity purification-mass spectrometry, and reduces POLR3BΔ10 protein levels in both cytoplasm and nucleus (western blot). In mice with postnatal oligodendrocyte-specific expression of the Δ10 mutant, defective oligodendrocyte precursor proliferation and differentiation results in failure to produce adequate mature oligodendrocytes during postnatal myelinogenesis, causing severe hypomyelination.\",\n      \"method\": \"Affinity purification–mass spectrometry (proteomics), western blot (subcellular fractionation), conditional mouse model with lineage tracing, immunofluorescence, immunohistochemistry, spectral confocal reflectance microscopy\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — proteomics for assembly defect, in vivo mouse model with lineage tracing defining the cellular mechanism, multiple orthogonal methods\",\n      \"pmids\": [\"37635302\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Intestinal epithelium-specific hypomorphic mutation of Polr3b (via VillinCre) in mice causes reduced proliferation, abnormal epithelial architecture, loss of Wnt signaling, and dramatic increase in apoptotic cells in crypts, demonstrating that Polr3b is required for intestinal crypt maintenance during early postnatal development. Lineage tracing showed that Polr3b-deficient crypts are replaced by wild-type escapers.\",\n      \"method\": \"Conditional mouse knockout (VillinCre), histology, genetic lineage tracing (Rosa26-lox-stop-lox-YFP), enteroid culture, molecular analysis\",\n      \"journal\": \"Cellular and molecular gastroenterology and hepatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean tissue-specific KO with defined proliferation/apoptosis/Wnt signaling phenotype and lineage tracing; multiple orthogonal methods\",\n      \"pmids\": [\"28090567\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The HLD8-associated nonsense mutation R550X in POLR3B causes the mutant protein to localize as aggregates in lysosomes (not in the nucleus as wild-type), decreases lysosome-related mTOR signaling, and inhibits oligodendroglial precursor cell morphological differentiation. Ibuprofen (NSAID) reversed the differentiation defect and improved mTOR signaling.\",\n      \"method\": \"Overexpression of wild-type vs. R550X POLR3B in FBD-102b oligodendroglial precursor cell line; immunofluorescence localization, mTOR signaling assay, morphological differentiation assay, ibuprofen treatment\",\n      \"journal\": \"Neurology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — cell-based overexpression with multiple readouts (localization, signaling, differentiation) but single lab and no in vivo confirmation\",\n      \"pmids\": [\"35225888\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"INMAP, a truncated isoform of POLR3B, localizes to the nucleus in a punctate pattern dependent on its 209–290 amino acid region, and overexpression of INMAP inhibits the transcriptional activities of p53 and AP-1 in a dose-dependent manner.\",\n      \"method\": \"Deletion analysis with subcellular localization (immunofluorescence), luciferase transcriptional reporter assays for p53 and AP-1 activity\",\n      \"journal\": \"Molecular and cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct reporter assays and localization mapping; single lab, overexpression-based, limited mechanistic depth\",\n      \"pmids\": [\"23124897\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"A POLR3B:c.1625A>G;p.(Asn542Ser) disease variant causes mis-splicing of POLR3B mRNA. In genome-edited HEK293 cells, this leads to decreased levels of multiple Pol III subunits and TFIIIB, but auto-upregulation of POLR3E (the Pol III termination-reinitiation subunit). La protein was increased relative to its pre-tRNA ligands. Transcription assays showed greater deficiency for tRNA genes with 4T terminators versus ≥5T terminators. La knockdown decreased Pol III ncRNA expression independently of RNA stability. Small-RNA sequencing showed increased tRNA fragments from pre-tRNA 3′-trailers (tRF-1) and elevated miRNAs, indicating that decreased Pol III output creates a functional excess of La protein that reshapes small ncRNA profiles.\",\n      \"method\": \"CRISPR genome editing (POLR3B HEK293 cells), RT-PCR (mis-splicing), western blot (subunit levels), cellular transcription assays, La protein knockdown, small-RNA sequencing (tRF and miRNA profiling), patient fibroblast analysis\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genome-edited cell model with multiple orthogonal methods; preprint, not yet peer-reviewed\",\n      \"pmids\": [\"38410490\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Polr3b heterozygous (Polr3b+/-) mice show sexually dimorphic, organ-specific effects: female Polr3b+/- mice have improved bone health but compromised gut barrier function and susceptibility to dermatitis; male Polr3b+/- mice are lighter with improved gut barrier function in old age. Neither sex showed extended lifespan, indicating reduced Pol III activity does not extend mammalian lifespan.\",\n      \"method\": \"Mouse genetics (Polr3b+/- C57BL/6N), longitudinal phenotypic analysis of bone, gut barrier, metabolic parameters\",\n      \"journal\": \"Aging cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic KO model with multiple organ-specific functional readouts; single lab, no molecular mechanism defined beyond reduced Pol III dosage\",\n      \"pmids\": [\"38465473\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"POLR3B (RPC2) encodes the second-largest catalytic subunit of RNA Polymerase III, forming the active center of the 17-subunit enzyme with POLR3A; it is essential for Pol III assembly (mediated in part by the PAQosome/HSP90 co-chaperone machinery), physically interacts with the Rpc11/POLR3K subunit to support RNA cleavage and polymerase recycling, and is required for Pol III transcription of tRNAs and other small non-coding RNAs — with loss-of-function causing defective oligodendrocyte precursor proliferation/differentiation (hypomyelination), intestinal crypt failure, and embryonic lethality at high severity, while dominant de novo missense variants cause aberrant subunit associations distinct from the assembly disruption seen with biallelic variants.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"POLR3B (RPC2) encodes the second-largest catalytic subunit of RNA Polymerase III, which together with POLR3A forms the active center of the enzyme that transcribes tRNAs and other small non-coding RNAs [#1]. Its structural integrity is required to recruit and retain the POLR3K/Rpc11 subunit within the polymerase; a deletion disrupting the Polr3b–Polr3k interface reduces Rpc11 in the assembled complex, and the resulting phenotype is rescued by restoring Rpc11 dosage [#0]. Pol III biogenesis proceeds through defined assembly stages assisted by the PAQosome/HSP90 co-chaperone machinery, and biallelic loss-of-function or severe hypomorphic POLR3B variants (e.g. R103H, Δ10) block proper complex assembly, whereas dominant de novo missense variants instead cause aberrant association of individual subunits without globally destabilizing the enzyme — establishing two distinct pathogenic mechanisms [#2, #3, #4, #5]. POLR3B function is essential in vivo: homozygous R103H is embryonically lethal in mice [#2], intestinal-specific hypomorphism causes crypt proliferation failure, Wnt-signaling loss and apoptosis [#6], and oligodendrocyte-specific expression of assembly-defective POLR3B impairs oligodendrocyte precursor proliferation and differentiation, producing severe hypomyelination [#5]. POLR3B variants cause hypomyelinating leukodystrophy through these mechanisms [#5, #7]. Reduced Pol III output also reshapes downstream small ncRNA profiles via a functional excess of La protein [#9].\"\n,\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Established that POLR3B's structural integrity is required to retain the Rpc11/POLR3K subunit in the Pol III complex, linking a specific protein–protein interface to enzyme function and phenotype.\",\n      \"evidence\": \"Zebrafish slim jim mutant characterization, comparable rpc2 deletion reconstituted in S. pombe with complex purification, and rescue by polr3k overexpression\",\n      \"pmids\": [\"18044988\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not define the atomic-resolution interface between POLR3B and POLR3K\", \"Does not establish whether reduced Rpc11 affects RNA cleavage versus recycling in human cells\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined POLR3B as the second-largest catalytic subunit contributing to the Pol III active center and established loss-of-function as a disease mechanism at the transcript level.\",\n      \"evidence\": \"Whole-exome sequencing of patients, RT-PCR of a splice-site product, and demonstration of nonsense-mediated decay\",\n      \"pmids\": [\"22036171\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not measure catalytic activity loss directly\", \"Does not connect transcript loss to a specific cellular tRNA/ncRNA deficit\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showed POLR3B is required in a specific tissue context — intestinal crypt maintenance — connecting Pol III activity to proliferation, Wnt signaling and survival.\",\n      \"evidence\": \"VillinCre conditional hypomorphic mouse, histology, lineage tracing, enteroid culture\",\n      \"pmids\": [\"28090567\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not identify which Pol III transcripts mediate the crypt phenotype\", \"Mechanism linking Pol III loss to Wnt signaling not defined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrated that the R103H missense allele acts by impairing Pol III complex assembly and is essential for embryonic viability, distinguishing assembly disruption as a quantifiable pathogenic readout.\",\n      \"evidence\": \"Proteomics in human cells expressing R103H plus mouse embryonic lethality genetics\",\n      \"pmids\": [\"31221184\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not define which assembly step is blocked\", \"Does not link assembly defect to a specific transcriptional output\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Distinguished dominant de novo missense variants — which cause aberrant subunit associations — from biallelic loss-of-function variants that disrupt overall assembly, defining two pathogenic mechanisms.\",\n      \"evidence\": \"Protein modeling and proteomics of patient-derived cells with de novo variants\",\n      \"pmids\": [\"33417887\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of aberrant subunit association on transcription not measured\", \"Single-lab proteomic dataset\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Resolved Pol III assembly into staged intermediates, implicated the PAQosome/HSP90 chaperone machinery in biogenesis, and showed pharmacological correction of an assembly defect.\",\n      \"evidence\": \"Mass spectrometry-based assembly assay, PAQosome interaction analysis, riluzole treatment in cells\",\n      \"pmids\": [\"36451185\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of riluzole correction not defined\", \"PAQosome dependence not tested in vivo\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Proposed an alternative, localization-based mechanism in which the R550X nonsense product mislocalizes to lysosomes and depresses mTOR signaling to block oligodendroglial differentiation.\",\n      \"evidence\": \"Overexpression of WT vs R550X in FBD-102b oligodendroglial precursors, localization, mTOR assay, differentiation assay, ibuprofen rescue\",\n      \"pmids\": [\"35225888\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Overexpression-based, no in vivo confirmation\", \"Relationship between lysosomal aggregation and loss of nuclear Pol III function not resolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined the cellular basis of hypomyelination by showing assembly-defective POLR3B impairs oligodendrocyte precursor proliferation and differentiation in vivo.\",\n      \"evidence\": \"AP-MS for assembly defect, subcellular western blot, conditional oligodendrocyte mouse model with lineage tracing and imaging\",\n      \"pmids\": [\"37635302\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which Pol III transcripts limit OPC maturation not identified\", \"Does not connect assembly defect to a molecular trigger of differentiation arrest\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Showed that reduced Pol III output reshapes the small ncRNA landscape through a functional excess of La protein, linking subunit deficiency to altered tRNA fragment and miRNA profiles.\",\n      \"evidence\": \"CRISPR-edited HEK293 POLR3B cells, RT-PCR, western blot, transcription assays, La knockdown, small-RNA sequencing, patient fibroblasts (preprint)\",\n      \"pmids\": [\"38410490\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not yet peer-reviewed\", \"Causal contribution of altered ncRNA profiles to disease phenotype untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Tested whether reduced Pol III dosage produces systemic or lifespan effects, revealing sexually dimorphic, organ-specific consequences without lifespan extension.\",\n      \"evidence\": \"Polr3b+/- mouse longitudinal phenotyping of bone, gut barrier and metabolic parameters\",\n      \"pmids\": [\"38465473\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular mechanism defined beyond reduced dosage\", \"Basis of sexual dimorphism unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved which specific Pol III transcripts mediate the tissue-selective phenotypes (oligodendrocyte, crypt) and how assembly-stage defects translate into defined transcriptional deficits.\",\n      \"evidence\": \"No timeline discovery links a specific Pol III ncRNA deficit to the cellular phenotypes\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No causal transcript identified for hypomyelination or crypt failure\", \"No structural model of human POLR3B–POLR3K interface\", \"Mechanistic reconciliation of nuclear assembly defect versus lysosomal mislocalization model lacking\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [5, 8]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [9]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [2, 4]}\n    ],\n    \"complexes\": [\n      \"RNA Polymerase III\"\n    ],\n    \"partners\": [\n      \"POLR3A\",\n      \"POLR3K\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}