{"gene":"ASCC1","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2018,"finding":"ASCC1 interacts physically with the ASCC3 helicase subunit of the ASCC complex, and loss of ASCC1 (via CRISPR/Cas9 knockout) causes increased ASCC3 foci formation during alkylation damage while most of these foci lack ASCC2, indicating ASCC1 coordinates proper recruitment and assembly of the ASCC complex during alkylation damage response.","method":"Co-immunoprecipitation, CRISPR/Cas9 knockout, fluorescence microscopy (foci formation), epistasis analysis with ASCC3","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal interaction mapping, CRISPR KO with defined cellular phenotype, epistasis with ASCC3, two orthogonal methods in one study","pmids":["29997253"],"is_preprint":false},{"year":2018,"finding":"ASCC1 is localized to nuclear speckle foci under basal conditions but leaves these foci in response to alkylation damage, a dynamic relocalization dependent on a putative RNA-binding motif near the ASCC1 C terminus.","method":"Fluorescence microscopy (subcellular localization), mutational analysis of C-terminal RNA-binding motif","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment with functional consequence, single lab, two orthogonal methods (imaging + mutagenesis)","pmids":["29997253"],"is_preprint":false},{"year":2018,"finding":"ASCC1 knockout results in sensitivity to alkylation damage in a manner epistatic with ASCC3, placing ASCC1 in the same pathway as ASCC3 for alkylation repair.","method":"CRISPR/Cas9 knockout, alkylation damage sensitivity assay, epistasis analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean genetic epistasis with defined phenotypic readout, CRISPR KO, single lab with multiple orthogonal methods","pmids":["29997253"],"is_preprint":false},{"year":2015,"finding":"Full-length ASCC1 potently inhibits NF-κB transcriptional activity (as measured by NF-κB-luciferase reporter and expression of NF-κB target genes TRAIL, TNF-α, cIAP-1, IL8) in five different human cell lines; a truncated variant (p.S78*) abrogates this inhibitory capacity and fails to reduce TNF-α secretion in response to inflammatory stimuli.","method":"NF-κB-luciferase reporter assay, qRT-PCR of NF-κB target genes, ELISA for TNF-α secretion, functional comparison of full-length vs. truncated ASCC1 in multiple cell lines","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal functional assays in five cell lines, single lab","pmids":["26503956"],"is_preprint":false},{"year":2024,"finding":"Crystal structures of Alvinella pompejana ASCC1 and the human ASCC1 PDE domain revealed a novel Helix-Clasp-Helix (HCH) nucleotide-binding motif within the KH domain enabling sequence-specific binding to CGCG-containing RNA, and a V-shaped PDE nucleotide-binding channel with two His-Φ-Ser/Thr-Φ motifs positioned for cyclic phosphate bond hydrolysis, suggesting phosphodiesterase activity on a novel substrate.","method":"X-ray crystallography (crystal structures of Ap and Hs ASCC1 domains), SAXS, bioinformatic/evolutionary analysis, RNA binding assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure determination with functional domain characterization and SAXS validation, single study with multiple orthogonal structural and biophysical methods","pmids":["38750793"],"is_preprint":false},{"year":2024,"finding":"SAXS analysis demonstrated that the KH and PDE domains of ASCC1 have aligned RNA binding sites with limited interdomain flexibility in solution, consistent with a coordinated RNA-binding function.","method":"Small-angle X-ray scattering (SAXS)","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — SAXS solution structure, single study, single method for this specific finding","pmids":["38750793"],"is_preprint":false},{"year":2023,"finding":"Knockdown of ASCC1 in human mesenchymal stromal cells (hMSCs) suppressed their differentiation into osteoblasts while increasing differentiation into adipocytes, resulting in reduced mineralization and elevated lipid droplet formation; this was accompanied by downregulation of RUNX2 (master regulator of osteoblastogenesis) and SERPINF1, and inhibition of TGF-β/SMAD signaling.","method":"siRNA knockdown of ASCC1 in hMSCs, osteoblast/adipocyte differentiation assays, mineralization assay, lipid droplet staining, proteomics, RNA sequencing, qPCR, pathway analysis","journal":"Frontiers in endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function in relevant cell type with defined differentiation phenotype and molecular pathway placement, multiple orthogonal methods, single lab","pmids":["37455927"],"is_preprint":false},{"year":2022,"finding":"A splicing variant in ASCC1 (c.395-2A>G) was shown by RNA analysis to produce two aberrant mRNA isoforms; a deletion of the first two coding exons leads to increased expression of a truncated transcript predicted to encode a protein with a shortened KH domain but intact RNA ligase-like (PDE) domain, suggesting domain-specific functional consequences of partial loss-of-function variants.","method":"RNA analysis (RT-PCR/cDNA sequencing), Kozak sequence prediction, transcript quantification","journal":"American journal of medical genetics. Part A","confidence":"Low","confidence_rationale":"Tier 3 / Weak — RNA-level characterization without direct protein functional assay, single lab, single method per finding","pmids":["35838082"],"is_preprint":false},{"year":2021,"finding":"A novel intronic ASCC1 variant (c.297-8 T>G) was shown by deep next-generation sequencing of parental cDNA to partially disrupt RNA splicing, providing a functional mechanism for pathogenicity of this non-canonical splice variant.","method":"Deep next-generation sequencing of cDNA, splicing analysis","journal":"American journal of medical genetics. Part A","confidence":"Low","confidence_rationale":"Tier 3 / Weak — splicing characterization at RNA level, single method, no protein functional assay","pmids":["33931933"],"is_preprint":false},{"year":2025,"finding":"A homozygous missense variant in ASCC1 affecting a highly conserved residue within the RNA-ligase-like (PDE) domain leads to nearly total absence of ASCC1 protein in muscle, demonstrating that missense variants in the PDE domain can cause loss of protein function.","method":"Protein expression analysis in muscle tissue (patient-derived), Sanger/exome sequencing","journal":"American journal of medical genetics. Part A","confidence":"Low","confidence_rationale":"Tier 3 / Weak — patient protein expression data, single case, no in vitro functional assay","pmids":["41230573"],"is_preprint":false}],"current_model":"ASCC1 is a multidomain protein (containing a KH/HCH RNA-binding domain and a two-histidine phosphodiesterase domain) that functions as a regulatory subunit of the ASCC complex: it physically interacts with the ASCC3 helicase, localizes to nuclear speckles under basal conditions and relocalizes upon alkylation damage, coordinates proper assembly and recruitment of the ASCC-ALKBH3 repair complex during alkylation damage response (acting epistatically with ASCC3), inhibits NF-κB transcriptional activation, and promotes osteoblastogenesis while suppressing adipogenesis in mesenchymal stromal cells via RUNX2 and TGF-β/SMAD signaling; structural studies reveal sequence-specific CGCG RNA binding and a PDE active site architecture consistent with cyclic phosphate hydrolase activity."},"narrative":{"mechanistic_narrative":"ASCC1 is a multidomain regulatory subunit of the ASCC (activating signal cointegrator) complex that coordinates the cellular response to DNA alkylation damage [PMID:29997253]. It physically interacts with the ASCC3 helicase, and its loss produces excess ASCC3 foci that fail to recruit ASCC2 during alkylation damage, establishing ASCC1 as an organizer of proper ASCC complex assembly and recruitment [PMID:29997253]. ASCC1 knockout sensitizes cells to alkylating agents in a manner genetically epistatic with ASCC3, placing the two proteins in a common alkylation-repair pathway [PMID:29997253]. Under basal conditions ASCC1 resides in nuclear speckles and relocalizes from them upon alkylation damage, a dynamic behavior dependent on a C-terminal RNA-binding motif [PMID:29997253]. Structurally, ASCC1 combines a KH domain bearing a Helix-Clasp-Helix motif that confers sequence-specific binding to CGCG-containing RNA with a two-histidine phosphodiesterase (PDE) domain whose active-site architecture is configured for cyclic phosphate hydrolysis, and these two RNA-binding surfaces are aligned in solution for a coordinated RNA-binding function [PMID:38750793]. Beyond its DNA-damage role, ASCC1 inhibits NF-κB transcriptional activation and suppresses inflammatory target-gene expression and TNF-α secretion [PMID:26503956], and it promotes osteoblast differentiation while restraining adipogenesis in mesenchymal stromal cells through RUNX2 and TGF-β/SMAD signaling [PMID:37455927]. Loss-of-function and splicing variants in ASCC1 have been linked to disease, with patient-derived evidence that PDE-domain missense variants abolish ASCC1 protein in muscle [PMID:41230573].","teleology":[{"year":2015,"claim":"Established the first functional role for ASCC1 outside complex assembly by showing it acts as a negative regulator of inflammatory transcription, and that a truncating variant abolishes this activity.","evidence":"NF-κB-luciferase reporter, qRT-PCR of target genes, and TNF-α ELISA comparing full-length versus p.S78* ASCC1 across five human cell lines","pmids":["26503956"],"confidence":"Medium","gaps":["Direct molecular target/interaction by which ASCC1 inhibits NF-κB not identified","Relationship between this transcriptional role and the ASCC complex/alkylation function unresolved"]},{"year":2018,"claim":"Defined ASCC1 as a physical and genetic partner of ASCC3 that organizes proper ASCC complex assembly and recruitment during alkylation damage, answering where ASCC1 acts in the repair pathway.","evidence":"Co-IP, CRISPR/Cas9 knockout with ASCC2/ASCC3 foci imaging, alkylation sensitivity, and epistasis with ASCC3 in human cells","pmids":["29997253"],"confidence":"High","gaps":["Molecular basis of how ASCC1 promotes ASCC2 recruitment to foci not resolved","Whether ASCC1 enzymatic activity contributes to repair untested"]},{"year":2018,"claim":"Showed ASCC1 localization is dynamic and RNA-motif-dependent, linking its subcellular behavior to damage signaling.","evidence":"Fluorescence microscopy of nuclear speckle localization plus mutational analysis of the C-terminal RNA-binding motif","pmids":["29997253"],"confidence":"Medium","gaps":["Identity of the RNA recognized in speckles not determined","Functional purpose of speckle exit upon damage unclear"]},{"year":2023,"claim":"Extended ASCC1 function to stromal cell fate, showing it drives osteoblastogenesis at the expense of adipogenesis via defined transcriptional and signaling effectors.","evidence":"siRNA knockdown in hMSCs with differentiation, mineralization, and lipid assays plus proteomics/RNA-seq implicating RUNX2, SERPINF1, and TGF-β/SMAD","pmids":["37455927"],"confidence":"Medium","gaps":["Whether ASCC1 acts directly or indirectly on RUNX2/TGF-β not established","Connection to the ASCC complex or RNA-binding activity not addressed"]},{"year":2024,"claim":"Provided structural mechanism for ASCC1 RNA recognition and putative catalysis, defining a CGCG-specific KH/HCH motif and a PDE active site poised for cyclic phosphate hydrolysis.","evidence":"X-ray crystallography of Alvinella pompejana and human ASCC1 domains, SAXS, RNA-binding assays, and evolutionary analysis","pmids":["38750793"],"confidence":"High","gaps":["Physiological RNA substrate of the PDE activity not identified","Catalytic activity not demonstrated biochemically on a defined substrate","Link between RNA binding/catalysis and alkylation repair untested"]},{"year":2025,"claim":"Connected ASCC1 disease variants to protein-level loss of function, showing a conserved PDE-domain missense variant nearly eliminates ASCC1 protein.","evidence":"Patient muscle protein expression analysis with exome/Sanger sequencing (single case)","pmids":["41230573"],"confidence":"Low","gaps":["Single case without in vitro functional confirmation","Mechanism linking ASCC1 loss to muscle/neuromuscular phenotype not established","Domain-specific contribution of PDE versus KH to disease unresolved"]},{"year":null,"claim":"The physiological RNA substrate of the ASCC1 PDE domain and the mechanistic link between its RNA-binding/catalytic activities and its roles in alkylation repair, NF-κB regulation, and stromal differentiation remain unknown.","evidence":"","pmids":[],"confidence":"Low","gaps":["No demonstrated catalytic turnover on an endogenous substrate","No unifying model connecting structural function to the multiple cellular phenotypes"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[1,4,5]},{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[4]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[3]}],"localization":[{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[1]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[0,2]}],"complexes":["ASCC complex"],"partners":["ASCC3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8N9N2","full_name":"Activating signal cointegrator 1 complex subunit 1","aliases":["ASC-1 complex subunit p50","Trip4 complex subunit p50"],"length_aa":400,"mass_kda":45.5,"function":"Plays a role in DNA damage repair as component of the ASCC complex (PubMed:29997253). Part of the ASC-1 complex that enhances NF-kappa-B, SRF and AP1 transactivation (PubMed:12077347). In cells responding to gastrin-activated paracrine signals, it is involved in the induction of SERPINB2 expression by gastrin. May also play a role in the development of neuromuscular junction","subcellular_location":"Nucleus; Nucleus speckle","url":"https://www.uniprot.org/uniprotkb/Q8N9N2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ASCC1","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"EIF3B","stoichiometry":0.2},{"gene":"EIF4A1","stoichiometry":0.2},{"gene":"GSPT1","stoichiometry":0.2},{"gene":"PSPC1","stoichiometry":0.2},{"gene":"RACK1","stoichiometry":0.2},{"gene":"RPS16","stoichiometry":0.2},{"gene":"SRP9","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/ASCC1","total_profiled":1310},"omim":[{"mim_id":"616867","title":"SPINAL MUSCULAR ATROPHY WITH CONGENITAL BONE FRACTURES 2; SMABF2","url":"https://www.omim.org/entry/616867"},{"mim_id":"616866","title":"SPINAL MUSCULAR ATROPHY WITH CONGENITAL BONE FRACTURES 1; SMABF1","url":"https://www.omim.org/entry/616866"},{"mim_id":"614266","title":"BARRETT ESOPHAGUS","url":"https://www.omim.org/entry/614266"},{"mim_id":"614217","title":"ACTIVATING SIGNAL COINTEGRATOR 1 COMPLEX, SUBUNIT 3; ASCC3","url":"https://www.omim.org/entry/614217"},{"mim_id":"614216","title":"ACTIVATING SIGNAL COINTEGRATOR 1 COMPLEX, SUBUNIT 2; ASCC2","url":"https://www.omim.org/entry/614216"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ASCC1"},"hgnc":{"alias_symbol":["CGI-18","ASC1p50","Em:AC022392.3","p50"],"prev_symbol":[]},"alphafold":{"accession":"Q8N9N2","domains":[{"cath_id":"3.30.1370.10","chopping":"44-70_89-160","consensus_level":"medium","plddt":69.9466,"start":44,"end":160},{"cath_id":"3.90.1140.10","chopping":"164-316_324-366","consensus_level":"high","plddt":79.894,"start":164,"end":366}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N9N2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N9N2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N9N2-F1-predicted_aligned_error_v6.png","plddt_mean":65.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ASCC1","jax_strain_url":"https://www.jax.org/strain/search?query=ASCC1"},"sequence":{"accession":"Q8N9N2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8N9N2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8N9N2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N9N2"}},"corpus_meta":[{"pmid":"21791690","id":"PMC_21791690","title":"Germline mutations in MSR1, ASCC1, and CTHRC1 in patients with Barrett esophagus and esophageal adenocarcinoma.","date":"2011","source":"JAMA","url":"https://pubmed.ncbi.nlm.nih.gov/21791690","citation_count":90,"is_preprint":false},{"pmid":"30327447","id":"PMC_30327447","title":"Novel ASCC1 mutations causing prenatal-onset muscle weakness with arthrogryposis and congenital bone fractures.","date":"2018","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30327447","citation_count":27,"is_preprint":false},{"pmid":"29997253","id":"PMC_29997253","title":"RNA ligase-like domain in activating signal cointegrator 1 complex subunit 1 (ASCC1) regulates ASCC complex function during alkylation damage.","date":"2018","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/29997253","citation_count":27,"is_preprint":false},{"pmid":"26503956","id":"PMC_26503956","title":"A Truncated Variant of ASCC1, a Novel Inhibitor of NF-κB, Is Associated with Disease Severity in Patients with Rheumatoid Arthritis.","date":"2015","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/26503956","citation_count":19,"is_preprint":false},{"pmid":"31880396","id":"PMC_31880396","title":"A new case of SMABF2 diagnosed in stillbirth expands the prenatal presentation and mutational spectrum of ASCC1.","date":"2019","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/31880396","citation_count":13,"is_preprint":false},{"pmid":"32160656","id":"PMC_32160656","title":"Novel compound heterozygous pathogenic variants in ASCC1 in a Chinese patient with spinal muscular atrophy with congenital bone fractures 2 : Evidence supporting a \"Definitive\" gene-disease relationship.","date":"2020","source":"Molecular genetics & genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/32160656","citation_count":8,"is_preprint":false},{"pmid":"38750793","id":"PMC_38750793","title":"ASCC1 structures and bioinformatics reveal a novel helix-clasp-helix RNA-binding motif linked to a two-histidine phosphodiesterase.","date":"2024","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/38750793","citation_count":7,"is_preprint":false},{"pmid":"33931933","id":"PMC_33931933","title":"Biallelic ASCC1 variants including a novel intronic variant result in expanded phenotypic spectrum of spinal muscular atrophy with congenital bone fractures 2 (SMABF2).","date":"2021","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/33931933","citation_count":6,"is_preprint":false},{"pmid":"32653958","id":"PMC_32653958","title":"Association between non-Caucasian-specific ASCC1 gene polymorphism and osteoporosis and obesity in Korean postmenopausal women.","date":"2020","source":"Journal of bone and mineral metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/32653958","citation_count":5,"is_preprint":false},{"pmid":"35838082","id":"PMC_35838082","title":"Congenital myopathy as a new phenotype caused by two undescribed variants in ASCC1 gene.","date":"2022","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/35838082","citation_count":5,"is_preprint":false},{"pmid":"37455927","id":"PMC_37455927","title":"Investigating the role of ASCC1 in the causation of bone fragility.","date":"2023","source":"Frontiers in endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/37455927","citation_count":4,"is_preprint":false},{"pmid":"41230573","id":"PMC_41230573","title":"Variant Update on ASCC1 : Characterization of the First Homozygous Missense Variant Involved in Prenatal-Onset Spinal Muscular Atrophy With Congenital Bone Fractures 2.","date":"2025","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/41230573","citation_count":2,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.02.04.25320393","title":"Genome-wide association study of neuropathic pain phenotypes implicates loci involved in neural cell adhesion, channels, collagen matrix formation and immune regulation","date":"2025-02-05","source":"bioRxiv","url":"https://doi.org/10.1101/2025.02.04.25320393","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9094,"output_tokens":2449,"usd":0.032009,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9696,"output_tokens":2707,"usd":0.058077,"stage2_stop_reason":"end_turn"},"total_usd":0.090086,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2018,\n      \"finding\": \"ASCC1 interacts physically with the ASCC3 helicase subunit of the ASCC complex, and loss of ASCC1 (via CRISPR/Cas9 knockout) causes increased ASCC3 foci formation during alkylation damage while most of these foci lack ASCC2, indicating ASCC1 coordinates proper recruitment and assembly of the ASCC complex during alkylation damage response.\",\n      \"method\": \"Co-immunoprecipitation, CRISPR/Cas9 knockout, fluorescence microscopy (foci formation), epistasis analysis with ASCC3\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal interaction mapping, CRISPR KO with defined cellular phenotype, epistasis with ASCC3, two orthogonal methods in one study\",\n      \"pmids\": [\"29997253\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ASCC1 is localized to nuclear speckle foci under basal conditions but leaves these foci in response to alkylation damage, a dynamic relocalization dependent on a putative RNA-binding motif near the ASCC1 C terminus.\",\n      \"method\": \"Fluorescence microscopy (subcellular localization), mutational analysis of C-terminal RNA-binding motif\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment with functional consequence, single lab, two orthogonal methods (imaging + mutagenesis)\",\n      \"pmids\": [\"29997253\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ASCC1 knockout results in sensitivity to alkylation damage in a manner epistatic with ASCC3, placing ASCC1 in the same pathway as ASCC3 for alkylation repair.\",\n      \"method\": \"CRISPR/Cas9 knockout, alkylation damage sensitivity assay, epistasis analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic epistasis with defined phenotypic readout, CRISPR KO, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"29997253\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Full-length ASCC1 potently inhibits NF-κB transcriptional activity (as measured by NF-κB-luciferase reporter and expression of NF-κB target genes TRAIL, TNF-α, cIAP-1, IL8) in five different human cell lines; a truncated variant (p.S78*) abrogates this inhibitory capacity and fails to reduce TNF-α secretion in response to inflammatory stimuli.\",\n      \"method\": \"NF-κB-luciferase reporter assay, qRT-PCR of NF-κB target genes, ELISA for TNF-α secretion, functional comparison of full-length vs. truncated ASCC1 in multiple cell lines\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal functional assays in five cell lines, single lab\",\n      \"pmids\": [\"26503956\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Crystal structures of Alvinella pompejana ASCC1 and the human ASCC1 PDE domain revealed a novel Helix-Clasp-Helix (HCH) nucleotide-binding motif within the KH domain enabling sequence-specific binding to CGCG-containing RNA, and a V-shaped PDE nucleotide-binding channel with two His-Φ-Ser/Thr-Φ motifs positioned for cyclic phosphate bond hydrolysis, suggesting phosphodiesterase activity on a novel substrate.\",\n      \"method\": \"X-ray crystallography (crystal structures of Ap and Hs ASCC1 domains), SAXS, bioinformatic/evolutionary analysis, RNA binding assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure determination with functional domain characterization and SAXS validation, single study with multiple orthogonal structural and biophysical methods\",\n      \"pmids\": [\"38750793\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SAXS analysis demonstrated that the KH and PDE domains of ASCC1 have aligned RNA binding sites with limited interdomain flexibility in solution, consistent with a coordinated RNA-binding function.\",\n      \"method\": \"Small-angle X-ray scattering (SAXS)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — SAXS solution structure, single study, single method for this specific finding\",\n      \"pmids\": [\"38750793\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Knockdown of ASCC1 in human mesenchymal stromal cells (hMSCs) suppressed their differentiation into osteoblasts while increasing differentiation into adipocytes, resulting in reduced mineralization and elevated lipid droplet formation; this was accompanied by downregulation of RUNX2 (master regulator of osteoblastogenesis) and SERPINF1, and inhibition of TGF-β/SMAD signaling.\",\n      \"method\": \"siRNA knockdown of ASCC1 in hMSCs, osteoblast/adipocyte differentiation assays, mineralization assay, lipid droplet staining, proteomics, RNA sequencing, qPCR, pathway analysis\",\n      \"journal\": \"Frontiers in endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function in relevant cell type with defined differentiation phenotype and molecular pathway placement, multiple orthogonal methods, single lab\",\n      \"pmids\": [\"37455927\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"A splicing variant in ASCC1 (c.395-2A>G) was shown by RNA analysis to produce two aberrant mRNA isoforms; a deletion of the first two coding exons leads to increased expression of a truncated transcript predicted to encode a protein with a shortened KH domain but intact RNA ligase-like (PDE) domain, suggesting domain-specific functional consequences of partial loss-of-function variants.\",\n      \"method\": \"RNA analysis (RT-PCR/cDNA sequencing), Kozak sequence prediction, transcript quantification\",\n      \"journal\": \"American journal of medical genetics. Part A\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — RNA-level characterization without direct protein functional assay, single lab, single method per finding\",\n      \"pmids\": [\"35838082\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"A novel intronic ASCC1 variant (c.297-8 T>G) was shown by deep next-generation sequencing of parental cDNA to partially disrupt RNA splicing, providing a functional mechanism for pathogenicity of this non-canonical splice variant.\",\n      \"method\": \"Deep next-generation sequencing of cDNA, splicing analysis\",\n      \"journal\": \"American journal of medical genetics. Part A\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — splicing characterization at RNA level, single method, no protein functional assay\",\n      \"pmids\": [\"33931933\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"A homozygous missense variant in ASCC1 affecting a highly conserved residue within the RNA-ligase-like (PDE) domain leads to nearly total absence of ASCC1 protein in muscle, demonstrating that missense variants in the PDE domain can cause loss of protein function.\",\n      \"method\": \"Protein expression analysis in muscle tissue (patient-derived), Sanger/exome sequencing\",\n      \"journal\": \"American journal of medical genetics. Part A\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — patient protein expression data, single case, no in vitro functional assay\",\n      \"pmids\": [\"41230573\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ASCC1 is a multidomain protein (containing a KH/HCH RNA-binding domain and a two-histidine phosphodiesterase domain) that functions as a regulatory subunit of the ASCC complex: it physically interacts with the ASCC3 helicase, localizes to nuclear speckles under basal conditions and relocalizes upon alkylation damage, coordinates proper assembly and recruitment of the ASCC-ALKBH3 repair complex during alkylation damage response (acting epistatically with ASCC3), inhibits NF-κB transcriptional activation, and promotes osteoblastogenesis while suppressing adipogenesis in mesenchymal stromal cells via RUNX2 and TGF-β/SMAD signaling; structural studies reveal sequence-specific CGCG RNA binding and a PDE active site architecture consistent with cyclic phosphate hydrolase activity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ASCC1 is a multidomain regulatory subunit of the ASCC (activating signal cointegrator) complex that coordinates the cellular response to DNA alkylation damage [#0, #2]. It physically interacts with the ASCC3 helicase, and its loss produces excess ASCC3 foci that fail to recruit ASCC2 during alkylation damage, establishing ASCC1 as an organizer of proper ASCC complex assembly and recruitment [#0]. ASCC1 knockout sensitizes cells to alkylating agents in a manner genetically epistatic with ASCC3, placing the two proteins in a common alkylation-repair pathway [#2]. Under basal conditions ASCC1 resides in nuclear speckles and relocalizes from them upon alkylation damage, a dynamic behavior dependent on a C-terminal RNA-binding motif [#1]. Structurally, ASCC1 combines a KH domain bearing a Helix-Clasp-Helix motif that confers sequence-specific binding to CGCG-containing RNA with a two-histidine phosphodiesterase (PDE) domain whose active-site architecture is configured for cyclic phosphate hydrolysis, and these two RNA-binding surfaces are aligned in solution for a coordinated RNA-binding function [#4, #5]. Beyond its DNA-damage role, ASCC1 inhibits NF-\\u03baB transcriptional activation and suppresses inflammatory target-gene expression and TNF-\\u03b1 secretion [#3], and it promotes osteoblast differentiation while restraining adipogenesis in mesenchymal stromal cells through RUNX2 and TGF-\\u03b2/SMAD signaling [#6]. Loss-of-function and splicing variants in ASCC1 have been linked to disease, with patient-derived evidence that PDE-domain missense variants abolish ASCC1 protein in muscle [#9].\",\n  \"teleology\": [\n    {\n      \"year\": 2015,\n      \"claim\": \"Established the first functional role for ASCC1 outside complex assembly by showing it acts as a negative regulator of inflammatory transcription, and that a truncating variant abolishes this activity.\",\n      \"evidence\": \"NF-\\u03baB-luciferase reporter, qRT-PCR of target genes, and TNF-\\u03b1 ELISA comparing full-length versus p.S78* ASCC1 across five human cell lines\",\n      \"pmids\": [\"26503956\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct molecular target/interaction by which ASCC1 inhibits NF-\\u03baB not identified\",\n        \"Relationship between this transcriptional role and the ASCC complex/alkylation function unresolved\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined ASCC1 as a physical and genetic partner of ASCC3 that organizes proper ASCC complex assembly and recruitment during alkylation damage, answering where ASCC1 acts in the repair pathway.\",\n      \"evidence\": \"Co-IP, CRISPR/Cas9 knockout with ASCC2/ASCC3 foci imaging, alkylation sensitivity, and epistasis with ASCC3 in human cells\",\n      \"pmids\": [\"29997253\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular basis of how ASCC1 promotes ASCC2 recruitment to foci not resolved\",\n        \"Whether ASCC1 enzymatic activity contributes to repair untested\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed ASCC1 localization is dynamic and RNA-motif-dependent, linking its subcellular behavior to damage signaling.\",\n      \"evidence\": \"Fluorescence microscopy of nuclear speckle localization plus mutational analysis of the C-terminal RNA-binding motif\",\n      \"pmids\": [\"29997253\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Identity of the RNA recognized in speckles not determined\",\n        \"Functional purpose of speckle exit upon damage unclear\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extended ASCC1 function to stromal cell fate, showing it drives osteoblastogenesis at the expense of adipogenesis via defined transcriptional and signaling effectors.\",\n      \"evidence\": \"siRNA knockdown in hMSCs with differentiation, mineralization, and lipid assays plus proteomics/RNA-seq implicating RUNX2, SERPINF1, and TGF-\\u03b2/SMAD\",\n      \"pmids\": [\"37455927\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether ASCC1 acts directly or indirectly on RUNX2/TGF-\\u03b2 not established\",\n        \"Connection to the ASCC complex or RNA-binding activity not addressed\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Provided structural mechanism for ASCC1 RNA recognition and putative catalysis, defining a CGCG-specific KH/HCH motif and a PDE active site poised for cyclic phosphate hydrolysis.\",\n      \"evidence\": \"X-ray crystallography of Alvinella pompejana and human ASCC1 domains, SAXS, RNA-binding assays, and evolutionary analysis\",\n      \"pmids\": [\"38750793\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Physiological RNA substrate of the PDE activity not identified\",\n        \"Catalytic activity not demonstrated biochemically on a defined substrate\",\n        \"Link between RNA binding/catalysis and alkylation repair untested\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected ASCC1 disease variants to protein-level loss of function, showing a conserved PDE-domain missense variant nearly eliminates ASCC1 protein.\",\n      \"evidence\": \"Patient muscle protein expression analysis with exome/Sanger sequencing (single case)\",\n      \"pmids\": [\"41230573\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Single case without in vitro functional confirmation\",\n        \"Mechanism linking ASCC1 loss to muscle/neuromuscular phenotype not established\",\n        \"Domain-specific contribution of PDE versus KH to disease unresolved\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The physiological RNA substrate of the ASCC1 PDE domain and the mechanistic link between its RNA-binding/catalytic activities and its roles in alkylation repair, NF-\\u03baB regulation, and stromal differentiation remain unknown.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No demonstrated catalytic turnover on an endogenous substrate\",\n        \"No unifying model connecting structural function to the multiple cellular phenotypes\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [1, 4, 5]},\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"complexes\": [\"ASCC complex\"],\n    \"partners\": [\"ASCC3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}