{"gene":"SCNM1","run_date":"2026-06-10T07:46:29","timeline":{"discoveries":[{"year":1999,"finding":"A modifier locus (Scnm1) on mouse chromosome 3 was identified that determines the severity of the neurological phenotype caused by a splice site mutation in Scn8a; the C57BL/6J background (sensitive allele of Scnm1) results in lethal juvenile paralysis, while the C3H background (resistant allele) produces viable dystonic adults, establishing Scnm1 as a trans-acting modifier of Scn8a splicing efficiency.","method":"Genetic mapping in F2 intercross mice; phenotypic analysis of modifier-dependent disease severity","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic mapping with 2304 F2 animals; single lab but replicated in subsequent studies","pmids":["9949206"],"is_preprint":false},{"year":2002,"finding":"Scnm1 acts by modulating splicing efficiency at the mutant splice donor site of Scn8a(medJ); the sensitive (C57BL/6J) modifier allele reduces correctly spliced Scn8a mRNA to 5% of wild-type, whereas the resistant allele allows 10%, leading to near-complete loss of Nav1.6 protein, delayed maturation of nodes of Ranvier, and slowed nerve conduction velocity.","method":"RT-PCR quantification of correctly spliced transcripts; Western blotting for Nav1.6 protein; nerve conduction velocity measurement; morphological analysis of nodes of Ranvier","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (transcript quantification, protein blotting, electrophysiology, morphology) in a well-controlled genetic system replicated across labs","pmids":["12374766"],"is_preprint":false},{"year":2003,"finding":"SCNM1 was identified as a zinc finger protein encoding a putative RNA splicing factor; the C57BL/6J susceptibility allele introduces a nonsense codon (R187X) into SCNM1, and an exon-skipping isoform due to disruption of a consensus exonic splicing enhancer is also predicted. Loss of full-length SCNM1 reduces correctly spliced Scn8a(medJ) transcripts below the survival threshold.","method":"Positional cloning; sequence analysis of SCNM1 alleles; comparison of correctly spliced Scn8a transcript levels between modifier genotypes","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 2 / Strong — positional cloning with functional transcript-level readout; replicated in subsequent targeted-allele studies","pmids":["12920299"],"is_preprint":false},{"year":2007,"finding":"SCNM1 has a direct role in splicing: (1) SCNM1 protein interacts with the spliceosomal protein U1-70K in yeast two-hybrid assays; (2) SCNM1 co-localizes with U1-70K in nuclear speckles in mammalian cells; (3) SCNM1 co-immunoprecipitates with core spliceosomal Sm proteins; (4) SCNM1 shows functional splicing activity in a minigene assay; (5) SCNM1 interacts with LUC7L2 (a protein involved in recognition of non-consensus splice donor sites) via its acidic C-terminal domain, which is truncated by the disease allele SCNM1(R187X).","method":"Yeast two-hybrid screen; co-immunoprecipitation with Sm proteins; co-localization by immunofluorescence in mammalian cells; minigene splicing assay; domain-deletion analysis","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (Y2H, Co-IP, immunofluorescence, functional splicing assay, domain mapping) in a single focused study","pmids":["17656373"],"is_preprint":false},{"year":2008,"finding":"A constitutive deletion of SCNM1 exons 3–5 (SCNM1Δ3-5) produces a protein that is correctly localized to the nucleus but is more functionally impaired than the C57BL/6J R187X allele in processing the Scn8a(medJ) transcript, confirming SCNM1's direct role as an auxiliary splice factor in vivo. Deficiency of SCNM1 did not broadly alter other brain transcripts tested.","method":"Targeted conditional knockout (floxed allele + Cre); nuclear localization by immunofluorescence; RT-PCR for Scn8a(medJ) splicing; transcript analysis of other brain genes","journal":"Genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean constitutive knockout with specific molecular phenotype replicated across alleles; nuclear localization directly demonstrated","pmids":["18791226"],"is_preprint":false},{"year":2021,"finding":"Cryo-EM structure of the activated human minor spliceosome at 2.9 Å resolution revealed that SCNM1 (a zinc finger protein) is a bona fide component of the minor spliceosome and functionally mimics the SF3a complex of the major spliceosome, stabilizing the conformation of the catalytic center.","method":"Cryo-electron microscopy at 2.9 Å resolution; atomic model building; structural comparison with major spliceosome SF3a","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — near-atomic resolution cryo-EM structure with functional annotation; high-impact peer-reviewed study","pmids":["33509932"],"is_preprint":false},{"year":2022,"finding":"Loss of SCNM1 function in human cells (patient fibroblasts with bi-allelic SCNM1 mutations, CRISPR-Cas9 SCNM1 knockout RPE-1 cells, and SCNM1 siRNA-treated RPE-1 cells) causes defective minor intron (U12) splicing of a specific set of genes including TMEM107 (primary cilia protein) and FAM92A (basal body protein), resulting in abnormally elongated primary cilia and impaired Hedgehog signaling. Retroviral re-introduction of wild-type SCNM1 rescued cilia length, gene expression, and Hh signaling, establishing SCNM1 as a positive mediator of Hh signaling through its U12 intron splicing activity.","method":"Comparative transcriptome analysis of patient fibroblasts vs. controls; CRISPR-Cas9 knockout; siRNA knockdown; RT-PCR/Western blot for U12-intron containing genes; immunofluorescence for cilia length; Hedgehog signaling assay; retroviral rescue experiment","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal loss-of-function approaches (patient cells, KO, KD) with rescue experiment and specific molecular and cellular phenotypic readouts","pmids":["36084634"],"is_preprint":false},{"year":2025,"finding":"A missense variant in the C2H2 zinc finger domain of SCNM1, p.(His68Arg), causes loss of SCNM1 function: patient fibroblasts homozygous for this variant show diminished expression of U12-intron containing genes (TMEM107, CIBAR1) and abnormal primary cilia, and the mutant SCNM1(His68Arg) protein fails to rescue the phenotype of SCNM1-deficient cells, demonstrating that the C2H2 zinc finger domain is essential for SCNM1 function.","method":"Exome sequencing; RT-PCR/Western blot for U12-intron gene expression in patient fibroblasts; immunofluorescence for primary cilia; rescue assay with mutant SCNM1 in SCNM1-deficient cells","journal":"Human genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — domain-level functional validation with rescue assay; single lab, multiple methods but limited replication","pmids":["41291844"],"is_preprint":false},{"year":2025,"finding":"In hepatocellular carcinoma cells, SCNM1 promotes tumor growth and suppresses apoptosis via its splicing activity, regulating downstream expression of DERL2 and BAG6 (proteins involved in protein degradation and apoptosis suppression); SCNM1 overexpression in HCC is driven by chromosome 1q copy number gain.","method":"Colony formation assay; apoptosis analysis; Western blotting for DERL2 and BAG6; RT-qPCR; correlation with SCNM1 expression in TCGA and GSE14520 datasets","journal":"Annals of surgical oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional cell-based assays with downstream target identification; single lab, limited mechanistic depth on splicing mechanism itself","pmids":["40172715"],"is_preprint":false}],"current_model":"SCNM1 is a zinc finger protein component of the human minor spliceosome that structurally mimics the SF3a complex to stabilize the catalytic center; it directly participates in recognition of non-consensus (weak) splice donor sites by interacting with U1-70K and LUC7L2 (via its acidic C-terminal domain) and co-localizing with Sm proteins in nuclear speckles, and its loss of function causes defective U12 intron splicing of genes encoding primary cilia and basal body proteins, leading to abnormal cilia elongation, impaired Hedgehog signaling, and in humans the ciliopathy orofaciodigital syndrome."},"narrative":{"mechanistic_narrative":"SCNM1 is a C2H2 zinc finger protein that functions as an auxiliary RNA splicing factor, originally identified as a trans-acting modifier (Scnm1) that determines the efficiency with which a mutant splice donor site in Scn8a is correctly processed and thereby sets neurological disease severity in mice [PMID:9949206, PMID:12920299]. It acts directly in splicing: it interacts with the spliceosomal protein U1-70K, co-immunoprecipitates with core Sm proteins, co-localizes with U1-70K in nuclear speckles, and shows activity in minigene splicing assays; its acidic C-terminal domain mediates interaction with LUC7L2, a factor implicated in recognition of non-consensus (weak) splice donor sites, and this domain is truncated by the R187X disease allele [PMID:17656373]. Cryo-EM of the activated human minor spliceosome established SCNM1 as a bona fide minor-spliceosome component that structurally mimics the major-spliceosome SF3a complex to stabilize the catalytic center [PMID:33509932]. Loss of SCNM1 function in human cells causes defective U12 (minor) intron splicing of a defined set of transcripts encoding primary cilia and basal body proteins, including TMEM107 and FAM92A, producing abnormally elongated primary cilia and impaired Hedgehog signaling, with wild-type SCNM1 re-introduction rescuing the defect [PMID:36084634]; the C2H2 zinc finger domain is essential for this function [PMID:41291844]. In hepatocellular carcinoma, SCNM1 is overexpressed via chromosome 1q copy-number gain and promotes tumor growth and apoptosis suppression through its splicing activity, regulating DERL2 and BAG6 [PMID:40172715].","teleology":[{"year":1999,"claim":"Established that an unknown locus could act in trans to modify the phenotypic severity of a splice-site mutation, framing the question of how a single gene tunes splicing efficiency of another.","evidence":"Genetic mapping in an F2 mouse intercross linking Scnm1 alleles to Scn8a-dependent disease severity","pmids":["9949206"],"confidence":"Medium","gaps":["Gene identity and molecular function not yet established","Mechanism of trans-modification unknown","No biochemical link to the spliceosome"]},{"year":2002,"claim":"Showed that the modifier acts quantitatively on splicing of the mutant Scn8a donor site, connecting reduced correctly-spliced mRNA to loss of Nav1.6 protein and electrophysiological/morphological deficits.","evidence":"RT-PCR transcript quantification, Western blot, nerve conduction velocity, and node-of-Ranvier morphology across modifier genotypes","pmids":["12374766"],"confidence":"High","gaps":["Molecular identity of the modifier still unknown","Whether the effect is direct or indirect on splicing not resolved"]},{"year":2003,"claim":"Identified the modifier as SCNM1, a zinc finger putative splicing factor, and pinpointed the R187X nonsense allele as the susceptibility variant reducing functional SCNM1.","evidence":"Positional cloning and allele sequencing with transcript-level functional readout","pmids":["12920299"],"confidence":"High","gaps":["Direct biochemical participation in splicing not yet demonstrated","Binding partners and spliceosomal context unknown"]},{"year":2007,"claim":"Demonstrated that SCNM1 physically engages the spliceosome and functions in splicing, mapping its LUC7L2 interaction to the C-terminal acidic domain lost in the disease allele.","evidence":"Yeast two-hybrid, Co-IP with Sm proteins, nuclear-speckle co-localization, minigene splicing assay, and domain-deletion mapping","pmids":["17656373"],"confidence":"High","gaps":["Spliceosome (major vs minor) membership not structurally defined","Y2H/Co-IP interactions lack structural context"]},{"year":2008,"claim":"Confirmed in vivo that SCNM1 is a direct auxiliary splice factor with a specific, not global, effect on transcript processing.","evidence":"Targeted constitutive deletion allele with nuclear localization, Scn8a(medJ) splicing RT-PCR, and survey of other brain transcripts","pmids":["18791226"],"confidence":"High","gaps":["Full repertoire of endogenous SCNM1-dependent splicing targets undefined","Mechanism of weak-donor recognition not resolved"]},{"year":2021,"claim":"Placed SCNM1 structurally within the activated minor spliceosome, revealing it mimics SF3a to stabilize the catalytic center.","evidence":"Cryo-EM of the human minor spliceosome at 2.9 Å with atomic modeling and comparison to major-spliceosome SF3a","pmids":["33509932"],"confidence":"High","gaps":["Functional consequences of minor-spliceosome role in cells not yet linked to phenotype","Disease-relevant target genes not identified from structure alone"]},{"year":2022,"claim":"Connected SCNM1 loss to defective U12-intron splicing of cilia/basal-body genes, abnormal cilia, and impaired Hedgehog signaling, with rescue establishing causality.","evidence":"Patient fibroblasts, CRISPR knockout and siRNA in RPE-1 cells, RT-PCR/Western for U12 targets, cilia immunofluorescence, Hh signaling assay, and retroviral rescue","pmids":["36084634"],"confidence":"High","gaps":["How specific U12 targets are selected by SCNM1 not defined","Mechanism linking cilia defect to Hh signaling step not fully resolved"]},{"year":2025,"claim":"Established the C2H2 zinc finger domain as essential for SCNM1 function via a pathogenic missense variant that fails to rescue.","evidence":"Exome sequencing, U12-target RT-PCR/Western in patient fibroblasts, cilia immunofluorescence, and rescue assay with mutant SCNM1","pmids":["41291844"],"confidence":"Medium","gaps":["Single lab, limited replication","Biochemical role of the zinc finger in target/RNA recognition not directly tested"]},{"year":2025,"claim":"Extended SCNM1 function to oncogenic context, showing copy-number-driven overexpression promotes HCC growth and apoptosis suppression through its splicing activity.","evidence":"Colony formation and apoptosis assays, Western blot of DERL2/BAG6, RT-qPCR, and TCGA/GSE14520 correlation","pmids":["40172715"],"confidence":"Medium","gaps":["Direct splicing mechanism on DERL2/BAG6 not demonstrated","Whether effect depends on minor-spliceosome activity unclear","Single lab, limited mechanistic depth"]},{"year":null,"claim":"How SCNM1 recognizes non-consensus/weak splice donor sites and selects its specific minor-intron target repertoire across tissues remains the central open question.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No direct demonstration of SCNM1 RNA-binding specificity","Target selection rules unknown","Tissue-specific consequences of partial loss undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[3,5,6]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[2,5]}],"localization":[{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[3,4]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[3,5,6]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[6]}],"complexes":["minor spliceosome"],"partners":["SNRNP70","LUC7L2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BWG6","full_name":"Sodium channel modifier 1","aliases":[],"length_aa":230,"mass_kda":25.9,"function":"As a component of the minor spliceosome, involved in the splicing of U12-type introns in pre-mRNAs (PubMed:36084634). Plays a role in the regulation of primary cilia length and Hedgehog signaling (PubMed:36084634)","subcellular_location":"Nucleus, nucleoplasm; Nucleus speckle","url":"https://www.uniprot.org/uniprotkb/Q9BWG6/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/SCNM1","classification":"Common Essential","n_dependent_lines":389,"n_total_lines":1208,"dependency_fraction":0.3220198675496689},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"SF3B1","stoichiometry":0.2},{"gene":"SF3B3","stoichiometry":0.2},{"gene":"SF3B6","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/SCNM1","total_profiled":1310},"omim":[{"mim_id":"620107","title":"OROFACIODIGITAL SYNDROME XIX; OFD19","url":"https://www.omim.org/entry/620107"},{"mim_id":"613056","title":"LUC7-LIKE 2 PRE-mRNA SPLICING FACTOR; LUC7L2","url":"https://www.omim.org/entry/613056"},{"mim_id":"608095","title":"SODIUM CHANNEL MODIFIER 1; SCNM1","url":"https://www.omim.org/entry/608095"},{"mim_id":"600702","title":"SODIUM VOLTAGE-GATED CHANNEL, ALPHA SUBUNIT 8; SCN8A","url":"https://www.omim.org/entry/600702"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SCNM1"},"hgnc":{"alias_symbol":["MGC3180"],"prev_symbol":[]},"alphafold":{"accession":"Q9BWG6","domains":[{"cath_id":"-","chopping":"10-79","consensus_level":"high","plddt":88.3647,"start":10,"end":79}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BWG6","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BWG6-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BWG6-F1-predicted_aligned_error_v6.png","plddt_mean":69.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SCNM1","jax_strain_url":"https://www.jax.org/strain/search?query=SCNM1"},"sequence":{"accession":"Q9BWG6","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BWG6.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BWG6/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BWG6"}},"corpus_meta":[{"pmid":"12920299","id":"PMC_12920299","title":"SCNM1, a putative RNA splicing factor that modifies disease severity in mice.","date":"2003","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/12920299","citation_count":110,"is_preprint":false},{"pmid":"12374766","id":"PMC_12374766","title":"Molecular and pathological effects of a modifier gene on deficiency of the sodium channel Scn8a (Na(v)1.6).","date":"2002","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/12374766","citation_count":89,"is_preprint":false},{"pmid":"33509932","id":"PMC_33509932","title":"Structure of the activated human minor spliceosome.","date":"2021","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/33509932","citation_count":73,"is_preprint":false},{"pmid":"9949206","id":"PMC_9949206","title":"Dystonia associated with mutation of the neuronal sodium channel Scn8a and identification of the modifier locus Scnm1 on mouse chromosome 3.","date":"1999","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/9949206","citation_count":62,"is_preprint":false},{"pmid":"17656373","id":"PMC_17656373","title":"Evidence for a direct role of the disease modifier SCNM1 in splicing.","date":"2007","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/17656373","citation_count":37,"is_preprint":false},{"pmid":"12706885","id":"PMC_12706885","title":"TSRC1, a widely expressed gene containing seven thrombospondin type I repeats.","date":"2003","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/12706885","citation_count":27,"is_preprint":false},{"pmid":"37895069","id":"PMC_37895069","title":"RNA Profiles of Tear Fluid Extracellular Vesicles in Patients with Dry Eye-Related Symptoms.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37895069","citation_count":22,"is_preprint":false},{"pmid":"36084634","id":"PMC_36084634","title":"Mutations in SCNM1 cause orofaciodigital syndrome due to minor intron splicing defects affecting primary cilia.","date":"2022","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36084634","citation_count":14,"is_preprint":false},{"pmid":"13679025","id":"PMC_13679025","title":"High-resolution mapping of the sodium channel modifier Scnm1 on mouse chromosome 3 and identification of a 1.3-kb recombination hot spot.","date":"2003","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/13679025","citation_count":12,"is_preprint":false},{"pmid":"35480309","id":"PMC_35480309","title":"Integrative Analysis of Nanopore and Illumina Sequencing Reveals Alternative Splicing Complexity in Pig Longissimus Dorsi Muscle.","date":"2022","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35480309","citation_count":12,"is_preprint":false},{"pmid":"18791226","id":"PMC_18791226","title":"A targeted deleterious allele of the splicing factor SCNM1 in the mouse.","date":"2008","source":"Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18791226","citation_count":8,"is_preprint":false},{"pmid":"26076849","id":"PMC_26076849","title":"Clinical and genetic analysis of a family with two rare reflex epilepsies.","date":"2015","source":"Seizure","url":"https://pubmed.ncbi.nlm.nih.gov/26076849","citation_count":6,"is_preprint":false},{"pmid":"19065122","id":"PMC_19065122","title":"Regulation of IL2 and NUCB1 in mononuclear cells treated with acyl glucuronide of mycophenolic acid reveals effects independent of inosine monophosphate dehydrogenase inhibition.","date":"2009","source":"Therapeutic drug monitoring","url":"https://pubmed.ncbi.nlm.nih.gov/19065122","citation_count":3,"is_preprint":false},{"pmid":"40172715","id":"PMC_40172715","title":"Clinical and Biological Significance of Sodium Channel Modifier 1 as a Component of the Minor Spliceosome in Hepatocellular Carcinoma.","date":"2025","source":"Annals of surgical oncology","url":"https://pubmed.ncbi.nlm.nih.gov/40172715","citation_count":1,"is_preprint":false},{"pmid":"41291844","id":"PMC_41291844","title":"Expanding the phenotype associated with biallelic SCNM1 variants.","date":"2025","source":"Human genomics","url":"https://pubmed.ncbi.nlm.nih.gov/41291844","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9232,"output_tokens":2724,"usd":0.034278,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9914,"output_tokens":3328,"usd":0.066385,"stage2_stop_reason":"end_turn"},"total_usd":0.100663,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1999,\n      \"finding\": \"A modifier locus (Scnm1) on mouse chromosome 3 was identified that determines the severity of the neurological phenotype caused by a splice site mutation in Scn8a; the C57BL/6J background (sensitive allele of Scnm1) results in lethal juvenile paralysis, while the C3H background (resistant allele) produces viable dystonic adults, establishing Scnm1 as a trans-acting modifier of Scn8a splicing efficiency.\",\n      \"method\": \"Genetic mapping in F2 intercross mice; phenotypic analysis of modifier-dependent disease severity\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic mapping with 2304 F2 animals; single lab but replicated in subsequent studies\",\n      \"pmids\": [\"9949206\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Scnm1 acts by modulating splicing efficiency at the mutant splice donor site of Scn8a(medJ); the sensitive (C57BL/6J) modifier allele reduces correctly spliced Scn8a mRNA to 5% of wild-type, whereas the resistant allele allows 10%, leading to near-complete loss of Nav1.6 protein, delayed maturation of nodes of Ranvier, and slowed nerve conduction velocity.\",\n      \"method\": \"RT-PCR quantification of correctly spliced transcripts; Western blotting for Nav1.6 protein; nerve conduction velocity measurement; morphological analysis of nodes of Ranvier\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (transcript quantification, protein blotting, electrophysiology, morphology) in a well-controlled genetic system replicated across labs\",\n      \"pmids\": [\"12374766\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"SCNM1 was identified as a zinc finger protein encoding a putative RNA splicing factor; the C57BL/6J susceptibility allele introduces a nonsense codon (R187X) into SCNM1, and an exon-skipping isoform due to disruption of a consensus exonic splicing enhancer is also predicted. Loss of full-length SCNM1 reduces correctly spliced Scn8a(medJ) transcripts below the survival threshold.\",\n      \"method\": \"Positional cloning; sequence analysis of SCNM1 alleles; comparison of correctly spliced Scn8a transcript levels between modifier genotypes\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — positional cloning with functional transcript-level readout; replicated in subsequent targeted-allele studies\",\n      \"pmids\": [\"12920299\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"SCNM1 has a direct role in splicing: (1) SCNM1 protein interacts with the spliceosomal protein U1-70K in yeast two-hybrid assays; (2) SCNM1 co-localizes with U1-70K in nuclear speckles in mammalian cells; (3) SCNM1 co-immunoprecipitates with core spliceosomal Sm proteins; (4) SCNM1 shows functional splicing activity in a minigene assay; (5) SCNM1 interacts with LUC7L2 (a protein involved in recognition of non-consensus splice donor sites) via its acidic C-terminal domain, which is truncated by the disease allele SCNM1(R187X).\",\n      \"method\": \"Yeast two-hybrid screen; co-immunoprecipitation with Sm proteins; co-localization by immunofluorescence in mammalian cells; minigene splicing assay; domain-deletion analysis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (Y2H, Co-IP, immunofluorescence, functional splicing assay, domain mapping) in a single focused study\",\n      \"pmids\": [\"17656373\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"A constitutive deletion of SCNM1 exons 3–5 (SCNM1Δ3-5) produces a protein that is correctly localized to the nucleus but is more functionally impaired than the C57BL/6J R187X allele in processing the Scn8a(medJ) transcript, confirming SCNM1's direct role as an auxiliary splice factor in vivo. Deficiency of SCNM1 did not broadly alter other brain transcripts tested.\",\n      \"method\": \"Targeted conditional knockout (floxed allele + Cre); nuclear localization by immunofluorescence; RT-PCR for Scn8a(medJ) splicing; transcript analysis of other brain genes\",\n      \"journal\": \"Genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean constitutive knockout with specific molecular phenotype replicated across alleles; nuclear localization directly demonstrated\",\n      \"pmids\": [\"18791226\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Cryo-EM structure of the activated human minor spliceosome at 2.9 Å resolution revealed that SCNM1 (a zinc finger protein) is a bona fide component of the minor spliceosome and functionally mimics the SF3a complex of the major spliceosome, stabilizing the conformation of the catalytic center.\",\n      \"method\": \"Cryo-electron microscopy at 2.9 Å resolution; atomic model building; structural comparison with major spliceosome SF3a\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — near-atomic resolution cryo-EM structure with functional annotation; high-impact peer-reviewed study\",\n      \"pmids\": [\"33509932\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Loss of SCNM1 function in human cells (patient fibroblasts with bi-allelic SCNM1 mutations, CRISPR-Cas9 SCNM1 knockout RPE-1 cells, and SCNM1 siRNA-treated RPE-1 cells) causes defective minor intron (U12) splicing of a specific set of genes including TMEM107 (primary cilia protein) and FAM92A (basal body protein), resulting in abnormally elongated primary cilia and impaired Hedgehog signaling. Retroviral re-introduction of wild-type SCNM1 rescued cilia length, gene expression, and Hh signaling, establishing SCNM1 as a positive mediator of Hh signaling through its U12 intron splicing activity.\",\n      \"method\": \"Comparative transcriptome analysis of patient fibroblasts vs. controls; CRISPR-Cas9 knockout; siRNA knockdown; RT-PCR/Western blot for U12-intron containing genes; immunofluorescence for cilia length; Hedgehog signaling assay; retroviral rescue experiment\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal loss-of-function approaches (patient cells, KO, KD) with rescue experiment and specific molecular and cellular phenotypic readouts\",\n      \"pmids\": [\"36084634\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"A missense variant in the C2H2 zinc finger domain of SCNM1, p.(His68Arg), causes loss of SCNM1 function: patient fibroblasts homozygous for this variant show diminished expression of U12-intron containing genes (TMEM107, CIBAR1) and abnormal primary cilia, and the mutant SCNM1(His68Arg) protein fails to rescue the phenotype of SCNM1-deficient cells, demonstrating that the C2H2 zinc finger domain is essential for SCNM1 function.\",\n      \"method\": \"Exome sequencing; RT-PCR/Western blot for U12-intron gene expression in patient fibroblasts; immunofluorescence for primary cilia; rescue assay with mutant SCNM1 in SCNM1-deficient cells\",\n      \"journal\": \"Human genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain-level functional validation with rescue assay; single lab, multiple methods but limited replication\",\n      \"pmids\": [\"41291844\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In hepatocellular carcinoma cells, SCNM1 promotes tumor growth and suppresses apoptosis via its splicing activity, regulating downstream expression of DERL2 and BAG6 (proteins involved in protein degradation and apoptosis suppression); SCNM1 overexpression in HCC is driven by chromosome 1q copy number gain.\",\n      \"method\": \"Colony formation assay; apoptosis analysis; Western blotting for DERL2 and BAG6; RT-qPCR; correlation with SCNM1 expression in TCGA and GSE14520 datasets\",\n      \"journal\": \"Annals of surgical oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional cell-based assays with downstream target identification; single lab, limited mechanistic depth on splicing mechanism itself\",\n      \"pmids\": [\"40172715\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SCNM1 is a zinc finger protein component of the human minor spliceosome that structurally mimics the SF3a complex to stabilize the catalytic center; it directly participates in recognition of non-consensus (weak) splice donor sites by interacting with U1-70K and LUC7L2 (via its acidic C-terminal domain) and co-localizing with Sm proteins in nuclear speckles, and its loss of function causes defective U12 intron splicing of genes encoding primary cilia and basal body proteins, leading to abnormal cilia elongation, impaired Hedgehog signaling, and in humans the ciliopathy orofaciodigital syndrome.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SCNM1 is a C2H2 zinc finger protein that functions as an auxiliary RNA splicing factor, originally identified as a trans-acting modifier (Scnm1) that determines the efficiency with which a mutant splice donor site in Scn8a is correctly processed and thereby sets neurological disease severity in mice [#0, #2]. It acts directly in splicing: it interacts with the spliceosomal protein U1-70K, co-immunoprecipitates with core Sm proteins, co-localizes with U1-70K in nuclear speckles, and shows activity in minigene splicing assays; its acidic C-terminal domain mediates interaction with LUC7L2, a factor implicated in recognition of non-consensus (weak) splice donor sites, and this domain is truncated by the R187X disease allele [#3]. Cryo-EM of the activated human minor spliceosome established SCNM1 as a bona fide minor-spliceosome component that structurally mimics the major-spliceosome SF3a complex to stabilize the catalytic center [#5]. Loss of SCNM1 function in human cells causes defective U12 (minor) intron splicing of a defined set of transcripts encoding primary cilia and basal body proteins, including TMEM107 and FAM92A, producing abnormally elongated primary cilia and impaired Hedgehog signaling, with wild-type SCNM1 re-introduction rescuing the defect [#6]; the C2H2 zinc finger domain is essential for this function [#7]. In hepatocellular carcinoma, SCNM1 is overexpressed via chromosome 1q copy-number gain and promotes tumor growth and apoptosis suppression through its splicing activity, regulating DERL2 and BAG6 [#8].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established that an unknown locus could act in trans to modify the phenotypic severity of a splice-site mutation, framing the question of how a single gene tunes splicing efficiency of another.\",\n      \"evidence\": \"Genetic mapping in an F2 mouse intercross linking Scnm1 alleles to Scn8a-dependent disease severity\",\n      \"pmids\": [\"9949206\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\n        \"Gene identity and molecular function not yet established\",\n        \"Mechanism of trans-modification unknown\",\n        \"No biochemical link to the spliceosome\"\n      ]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Showed that the modifier acts quantitatively on splicing of the mutant Scn8a donor site, connecting reduced correctly-spliced mRNA to loss of Nav1.6 protein and electrophysiological/morphological deficits.\",\n      \"evidence\": \"RT-PCR transcript quantification, Western blot, nerve conduction velocity, and node-of-Ranvier morphology across modifier genotypes\",\n      \"pmids\": [\"12374766\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\n        \"Molecular identity of the modifier still unknown\",\n        \"Whether the effect is direct or indirect on splicing not resolved\"\n      ]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identified the modifier as SCNM1, a zinc finger putative splicing factor, and pinpointed the R187X nonsense allele as the susceptibility variant reducing functional SCNM1.\",\n      \"evidence\": \"Positional cloning and allele sequencing with transcript-level functional readout\",\n      \"pmids\": [\"12920299\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\n        \"Direct biochemical participation in splicing not yet demonstrated\",\n        \"Binding partners and spliceosomal context unknown\"\n      ]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrated that SCNM1 physically engages the spliceosome and functions in splicing, mapping its LUC7L2 interaction to the C-terminal acidic domain lost in the disease allele.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP with Sm proteins, nuclear-speckle co-localization, minigene splicing assay, and domain-deletion mapping\",\n      \"pmids\": [\"17656373\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\n        \"Spliceosome (major vs minor) membership not structurally defined\",\n        \"Y2H/Co-IP interactions lack structural context\"\n      ]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Confirmed in vivo that SCNM1 is a direct auxiliary splice factor with a specific, not global, effect on transcript processing.\",\n      \"evidence\": \"Targeted constitutive deletion allele with nuclear localization, Scn8a(medJ) splicing RT-PCR, and survey of other brain transcripts\",\n      \"pmids\": [\"18791226\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\n        \"Full repertoire of endogenous SCNM1-dependent splicing targets undefined\",\n        \"Mechanism of weak-donor recognition not resolved\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Placed SCNM1 structurally within the activated minor spliceosome, revealing it mimics SF3a to stabilize the catalytic center.\",\n      \"evidence\": \"Cryo-EM of the human minor spliceosome at 2.9 Å with atomic modeling and comparison to major-spliceosome SF3a\",\n      \"pmids\": [\"33509932\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\n        \"Functional consequences of minor-spliceosome role in cells not yet linked to phenotype\",\n        \"Disease-relevant target genes not identified from structure alone\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Connected SCNM1 loss to defective U12-intron splicing of cilia/basal-body genes, abnormal cilia, and impaired Hedgehog signaling, with rescue establishing causality.\",\n      \"evidence\": \"Patient fibroblasts, CRISPR knockout and siRNA in RPE-1 cells, RT-PCR/Western for U12 targets, cilia immunofluorescence, Hh signaling assay, and retroviral rescue\",\n      \"pmids\": [\"36084634\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\n        \"How specific U12 targets are selected by SCNM1 not defined\",\n        \"Mechanism linking cilia defect to Hh signaling step not fully resolved\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Established the C2H2 zinc finger domain as essential for SCNM1 function via a pathogenic missense variant that fails to rescue.\",\n      \"evidence\": \"Exome sequencing, U12-target RT-PCR/Western in patient fibroblasts, cilia immunofluorescence, and rescue assay with mutant SCNM1\",\n      \"pmids\": [\"41291844\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\n        \"Single lab, limited replication\",\n        \"Biochemical role of the zinc finger in target/RNA recognition not directly tested\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended SCNM1 function to oncogenic context, showing copy-number-driven overexpression promotes HCC growth and apoptosis suppression through its splicing activity.\",\n      \"evidence\": \"Colony formation and apoptosis assays, Western blot of DERL2/BAG6, RT-qPCR, and TCGA/GSE14520 correlation\",\n      \"pmids\": [\"40172715\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\n        \"Direct splicing mechanism on DERL2/BAG6 not demonstrated\",\n        \"Whether effect depends on minor-spliceosome activity unclear\",\n        \"Single lab, limited mechanistic depth\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SCNM1 recognizes non-consensus/weak splice donor sites and selects its specific minor-intron target repertoire across tissues remains the central open question.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\n        \"No direct demonstration of SCNM1 RNA-binding specificity\",\n        \"Target selection rules unknown\",\n        \"Tissue-specific consequences of partial loss undefined\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [3, 5, 6]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [2, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [3, 4]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [3, 5, 6]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"complexes\": [\n      \"minor spliceosome\"\n    ],\n    \"partners\": [\n      \"SNRNP70\",\n      \"LUC7L2\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}