{"gene":"SUDS3","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":1996,"finding":"Genetic epistasis experiments in S. cerevisiae suggested SDS3 functions in a pathway related to, but potentially separable from, SIN3 and RPD3 in transcriptional silencing at HMR; sds3 mutations increase silencing at HML, HMR, and telomere-linked genes, similar to sin3 and rpd3 mutants, and SDS3 represses IME2 in haploid cells and is required for sporulation.","method":"Genetic screen for suppressors of defective silencing, epistasis analysis, reporter assays","journal":"Genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — genetic epistasis in yeast, single lab, no biochemical confirmation of complex membership","pmids":["8978024"],"is_preprint":false},{"year":2000,"finding":"Yeast Sds3p is an integral subunit of the high-molecular-weight Rpd3p·Sin3p histone deacetylase complex; in the absence of Sds3p, Sin3p and Rpd3p can be chromatographically separated, and the remaining Rpd3p complex has little or no HDAC activity, demonstrating that Sds3p is required for both complex integrity and catalytic activity.","method":"Biochemical fractionation (chromatography), co-immunoprecipitation, in vitro HDAC activity assay in sds3Δ yeast strain","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — biochemical reconstitution-level fractionation, HDAC activity assay, genetic deletion strain, replicated across labs","pmids":["11024051"],"is_preprint":false},{"year":2000,"finding":"Genetic analysis in S. cerevisiae demonstrates that SDS3 functions in the same genetic pathway as SIN3 and RPD3, and co-immunoprecipitation confirms that Sds3 is physically present in the Sin3 complex.","method":"Genetic epistasis analysis, co-immunoprecipitation","journal":"Genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal genetic and biochemical evidence, two orthogonal methods, single lab","pmids":["10655212"],"is_preprint":false},{"year":2002,"finding":"Mammalian Sds3 (mSds3) was identified as an integral component of the mSin3A/mSin3B-HDAC corepressor complex: it physically associates with mSin3 proteins in vivo, represses transcription in a partially HDAC-dependent manner, and is required to enable HDAC1 catalytic activity in vivo.","method":"Co-immunoprecipitation (in vivo association with mSin3), transcriptional repression assays, HDAC activity assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (Co-IP, transcription assay, HDAC activity assay), replicated functional parallel with yeast SDS3","pmids":["11909966"],"is_preprint":false},{"year":2011,"finding":"Human SDS3 undergoes endogenous Lys-63-linked (but not Lys-48-linked) polyubiquitination; the deubiquitinase USP17 physically interacts with SDS3 (shown by MALDI-TOF-MS, co-immunoprecipitation, and GST pull-down) and specifically removes Lys-63-linked ubiquitin chains from SDS3, which negatively regulates SDS3-associated HDAC activity.","method":"Co-immunoprecipitation, GST pull-down, MALDI-TOF-MS, ubiquitination linkage-specific assays, HDAC activity assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal biochemical methods (MS, Co-IP, GST pull-down, activity assay), single lab but rigorous","pmids":["21239494"],"is_preprint":false},{"year":2012,"finding":"SDS3 contains hyaluronan binding motifs (HABMs) and directly binds hyaluronan (HA); deletion of HABMs in USP17 reduces its interaction with SDS3 but does not alter USP17's deubiquitinating activity toward SDS3 or USP17's functional regulation of SDS3-associated HDAC activity.","method":"CPC (cetylpyridinium chloride) binding assay, co-immunoprecipitation with HABM-deletion mutants, HDAC activity assay, soft agar/apoptosis/migration assays","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assay and mutagenesis with functional readout, single lab, two orthogonal methods","pmids":["22662218"],"is_preprint":false},{"year":2012,"finding":"Knockdown of Suds3 in mouse blastocysts disrupts FGF4/ERK signaling, impairs trophectoderm proliferation, and abolishes primitive endoderm formation, establishing that Suds3/Sin3/HDAC complexes are required for early lineage specification; exogenous FGF4 rescues these defects.","method":"Suds3 knockdown in mouse preimplantation embryos, immunofluorescence for lineage markers, FGF4 rescue experiment, HDAC1 knockdown comparison","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with specific molecular rescue, two knockdown conditions, single lab","pmids":["23123966"],"is_preprint":false},{"year":2012,"finding":"SDS3 associates with ARNT (in a TCDD ligand-specific, but not B(a)P-specific, manner) as part of the Sin3/HDAC repressor complex, and reduction of SDS3 protein de-represses cKrox and S100A4 expression in CD4+CD8+ DPK thymocytes, placing SDS3 in AhR/ARNT ligand-specific transcriptional repression.","method":"Co-immunoprecipitation with anti-ARNT antibody, SDS3 protein knockdown, gene expression analysis","journal":"Environmental toxicology and pharmacology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP and knockdown, single lab, limited mechanistic follow-up","pmids":["22981438"],"is_preprint":false},{"year":2015,"finding":"Solution NMR revealed that the Sds3 Sin3 interaction domain (SID) samples two discrete conformations with lifetimes in the tens of milliseconds range, differing by a 5–7 Å translation of the main chain; Sds3 engages Sin3A via a bipartite motif within the SID comprising a helix and an extended segment, and Sds3 provides a homodimerization activity required for assembly of the 1–2 MDa Sin3L/Rpd3L complex.","method":"Solution NMR spectroscopy with functional validation of conformational exchange","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — NMR structural data, single lab, limited mutagenesis/functional follow-up reported in abstract","pmids":["26522936"],"is_preprint":false},{"year":2024,"finding":"SDS3 modulates expression of ASK1, the upstream kinase of the p38 MAPK pathway, in microglia, thereby regulating p38 MAPK signaling activation and microglial inflammatory responses; SDS3 target genes were identified by chromatin immunoprecipitation combined with transcriptomics and proteomics.","method":"Chromatin immunoprecipitation (ChIP), SDS3 knockdown, transcriptomics, proteomics, downstream pathway validation","journal":"Inflammation research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP plus multi-omics with functional validation, single lab, two orthogonal approaches","pmids":["39008037"],"is_preprint":false},{"year":2008,"finding":"SUDS3 over-expression in BRMS1-non-expressing metastatic breast cancer cells did not suppress metastasis, motility, osteopontin secretion, or EGF receptor expression, demonstrating that SUDS3 and BRMS1 have functionally distinct roles within SIN3-HDAC complexes despite structural relatedness.","method":"SUDS3 over-expression in metastatic cell lines, motility assays, soft agar assay, EGF receptor expression analysis","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple functional assays, negative result mechanistically informative, single lab","pmids":["19070953"],"is_preprint":false}],"current_model":"SUDS3/SDS3 is an integral, conserved subunit of the Sin3/HDAC corepressor complex that homodimerizes and engages Sin3A via a bipartite SID motif (resolved by NMR), is essential for the physical integrity of the complex and for HDAC1/2 catalytic activity, represses transcription at specific target genes (including ASK1) through chromatin deacetylation, undergoes Lys-63-linked polyubiquitination that is removed by the deubiquitinase USP17 to negatively regulate HDAC activity, and in early mammalian development is required for FGF4/ERK signaling and lineage specification."},"narrative":{"mechanistic_narrative":"SUDS3/SDS3 is a conserved, integral subunit of the Sin3/Rpd3(HDAC) corepressor complex that is essential for both the physical integrity of the complex and its histone deacetylase catalytic output [PMID:11024051, PMID:11909966]. First defined genetically in yeast as a factor acting in the same transcriptional-silencing pathway as SIN3 and RPD3 [PMID:8978024, PMID:10655212], Sds3 was shown by chromatographic fractionation to be required to hold Sin3 and Rpd3 together; loss of Sds3 separates the subunits and abolishes HDAC activity [PMID:11024051]. The mammalian ortholog associates with mSin3A/mSin3B in vivo, represses transcription in an HDAC-dependent manner, and is required to enable HDAC1 catalytic activity [PMID:11909966]. Structurally, Sds3 engages Sin3A through a bipartite Sin3-interaction domain (SID) comprising a helix and an extended segment that samples two discrete conformations, and provides a homodimerization activity needed to assemble the 1–2 MDa Sin3L/Rpd3L complex [PMID:26522936]. SDS3-associated HDAC activity is negatively regulated by a ubiquitin switch: SDS3 carries Lys-63-linked polyubiquitin chains that the deubiquitinase USP17 removes through a direct physical interaction [PMID:21239494]. Through chromatin deacetylation at specific targets, SDS3 represses genes including ASK1 to control p38 MAPK signaling and microglial inflammatory responses [PMID:39008037], and is required in early mouse development for FGF4/ERK-dependent lineage specification [PMID:23123966].","teleology":[{"year":1996,"claim":"Established that SDS3 acts in transcriptional silencing alongside SIN3 and RPD3, raising the question of whether it is a dedicated component of the same machinery.","evidence":"Suppressor genetic screen and epistasis with reporter assays in S. cerevisiae","pmids":["8978024"],"confidence":"Medium","gaps":["Genetic only — no biochemical demonstration of complex membership","Did not show whether SDS3 is required for HDAC activity"]},{"year":2000,"claim":"Defined the core mechanistic role of Sds3 by showing it is physically required to hold the Rpd3·Sin3 complex together and to sustain its deacetylase activity.","evidence":"Chromatographic fractionation, Co-IP, and in vitro HDAC assays in sds3Δ yeast; complemented by reciprocal genetic/Co-IP analysis","pmids":["11024051","10655212"],"confidence":"High","gaps":["Structural basis of how Sds3 bridges Sin3 and Rpd3 not resolved","Conducted in yeast — mammalian relevance not yet shown"]},{"year":2002,"claim":"Extended the function to mammals, establishing mSds3 as an integral Sin3A/B-HDAC subunit required for HDAC1 catalytic activity in vivo.","evidence":"Co-IP with mSin3, transcriptional repression assays, and HDAC activity assays in mammalian cells","pmids":["11909966"],"confidence":"High","gaps":["Specific target genes in mammals not defined","Domain mediating Sin3 contact not mapped"]},{"year":2011,"claim":"Identified a post-translational control of SDS3-associated HDAC activity, showing K63-linked ubiquitination of SDS3 is reversed by USP17 to tune deacetylase output.","evidence":"Co-IP, GST pull-down, MALDI-TOF-MS, linkage-specific ubiquitination and HDAC activity assays","pmids":["21239494"],"confidence":"High","gaps":["E3 ligase adding the K63 chains not identified","Site of ubiquitination on SDS3 not mapped"]},{"year":2012,"claim":"Resolved the molecular interface and oligomeric requirement, showing SDS3 binds Sin3A via a bipartite SID and homodimerizes to assemble the megadalton Sin3L/Rpd3L complex.","evidence":"Solution NMR spectroscopy with conformational-exchange analysis","pmids":["26522936"],"confidence":"Medium","gaps":["Limited mutagenesis/functional validation of the dimerization interface","No full complex structure"]},{"year":2012,"claim":"Connected SDS3 to specific physiological repression programs, including ligand-specific AhR/ARNT repression and a non-canonical hyaluronan-binding activity.","evidence":"Co-IP with ARNT plus knockdown in thymocytes; CPC hyaluronan binding and HABM-deletion assays","pmids":["22981438","22662218"],"confidence":"Low","gaps":["ARNT association rests on single Co-IP and knockdown without reciprocal validation","Functional consequence of hyaluronan binding unresolved"]},{"year":2012,"claim":"Placed SDS3 in a developmental program, showing it is required for FGF4/ERK signaling and primitive endoderm lineage specification in early mouse embryos.","evidence":"Suds3 knockdown in mouse blastocysts with lineage-marker immunofluorescence and FGF4 rescue","pmids":["23123966"],"confidence":"Medium","gaps":["Direct transcriptional targets mediating FGF4 regulation not identified","Single-lab knockdown without genetic null"]},{"year":2024,"claim":"Identified direct SDS3 target genes, showing repression of ASK1 controls p38 MAPK activation and microglial inflammation.","evidence":"ChIP combined with transcriptomics/proteomics, SDS3 knockdown, and downstream pathway validation","pmids":["39008037"],"confidence":"Medium","gaps":["Whether ASK1 regulation generalizes beyond microglia unknown","Recruitment of the complex to the ASK1 locus not defined"]},{"year":null,"claim":"How SDS3 recruitment, its ubiquitin switch, and its bipartite Sin3 interface are integrated to direct target-gene selection across tissues remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["E3 ligase and ubiquitination sites unmapped","Genome-wide target catalog incomplete","No integrated structure of the assembled complex"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,3,9]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[1,3,4]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,8]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1,3,9]}],"pathway":[{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[1,3]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[3,9]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[6]}],"complexes":["Sin3/HDAC corepressor complex","Rpd3L (Sin3L) histone deacetylase complex"],"partners":["SIN3A","SIN3B","HDAC1","USP17","ARNT"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9H7L9","full_name":"Sin3 histone deacetylase corepressor complex component SDS3","aliases":["45 kDa Sin3-associated polypeptide","Suppressor of defective silencing 3 protein homolog"],"length_aa":328,"mass_kda":38.1,"function":"Regulatory protein which represses transcription and augments histone deacetylase activity of HDAC1. May have a potential role in tumor suppressor pathways through regulation of apoptosis. May function in the assembly and/or enzymatic activity of the mSin3A corepressor complex or in mediating interactions between the complex and other regulatory complexes","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9H7L9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/SUDS3","classification":"Common Essential","n_dependent_lines":609,"n_total_lines":1208,"dependency_fraction":0.5041390728476821},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CSNK2B","stoichiometry":0.2},{"gene":"H2AFZ","stoichiometry":0.2},{"gene":"HDAC1","stoichiometry":0.2},{"gene":"HDAC2","stoichiometry":0.2},{"gene":"RBBP4","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/SUDS3","total_profiled":1310},"omim":[{"mim_id":"608250","title":"SDS3 HOMOLOG, SIN3A COREPRESSOR COMPLEX COMPONENT; SUDS3","url":"https://www.omim.org/entry/608250"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nuclear bodies","reliability":"Supported"},{"location":"Cytosol","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SUDS3"},"hgnc":{"alias_symbol":["SDS3","FLJ00052","SAP45"],"prev_symbol":[]},"alphafold":{"accession":"Q9H7L9","domains":[{"cath_id":"2.30.30","chopping":"254-323","consensus_level":"high","plddt":92.7889,"start":254,"end":323}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H7L9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H7L9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H7L9-F1-predicted_aligned_error_v6.png","plddt_mean":78.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SUDS3","jax_strain_url":"https://www.jax.org/strain/search?query=SUDS3"},"sequence":{"accession":"Q9H7L9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9H7L9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9H7L9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H7L9"}},"corpus_meta":[{"pmid":"11909966","id":"PMC_11909966","title":"Identification of mammalian Sds3 as an integral component of the Sin3/histone deacetylase corepressor complex.","date":"2002","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/11909966","citation_count":100,"is_preprint":false},{"pmid":"11024051","id":"PMC_11024051","title":"Sds3 (suppressor of defective silencing 3) is an integral component of the yeast Sin3[middle dot]Rpd3 histone deacetylase complex and is required for histone deacetylase activity.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11024051","citation_count":84,"is_preprint":false},{"pmid":"8978024","id":"PMC_8978024","title":"Evidence that the transcriptional regulators SIN3 and RPD3, and a novel gene (SDS3) with similar functions, are involved in transcriptional silencing in S. cerevisiae.","date":"1996","source":"Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8978024","citation_count":66,"is_preprint":false},{"pmid":"10655212","id":"PMC_10655212","title":"Roles for the Saccharomyces cerevisiae SDS3, CBK1 and HYM1 genes in transcriptional repression by SIN3.","date":"2000","source":"Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10655212","citation_count":40,"is_preprint":false},{"pmid":"21239494","id":"PMC_21239494","title":"Lys-63-specific deubiquitination of SDS3 by USP17 regulates HDAC activity.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21239494","citation_count":35,"is_preprint":false},{"pmid":"32565736","id":"PMC_32565736","title":"Long non-coding RNA SNHG22 facilitates the malignant phenotypes in triple-negative breast cancer via sponging miR-324-3p and upregulating SUDS3.","date":"2020","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/32565736","citation_count":28,"is_preprint":false},{"pmid":"22662218","id":"PMC_22662218","title":"Hyaluronan binding motifs of USP17 and SDS3 exhibit anti-tumor activity.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22662218","citation_count":20,"is_preprint":false},{"pmid":"23123966","id":"PMC_23123966","title":"Depletion of Suds3 reveals an essential role in early lineage specification.","date":"2012","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/23123966","citation_count":19,"is_preprint":false},{"pmid":"19070953","id":"PMC_19070953","title":"Over-expression of the BRMS1 family member SUDS3 does not suppress metastasis of human cancer cells.","date":"2008","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/19070953","citation_count":19,"is_preprint":false},{"pmid":"39008037","id":"PMC_39008037","title":"SDS3 regulates microglial inflammation by modulating the expression of the upstream kinase ASK1 in the p38 MAPK signaling pathway.","date":"2024","source":"Inflammation research : official journal of the European Histamine Research Society ... [et al.]","url":"https://pubmed.ncbi.nlm.nih.gov/39008037","citation_count":5,"is_preprint":false},{"pmid":"26522936","id":"PMC_26522936","title":"Solution NMR Studies of an Alternative Mode of Sin3 Engagement by the Sds3 Subunit in the Histone Deacetylase-Associated Sin3L/Rpd3L Corepressor Complex.","date":"2015","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/26522936","citation_count":4,"is_preprint":false},{"pmid":"22981438","id":"PMC_22981438","title":"SDS3 interacts with ARNT in an AhR ligand-specific manner regulating expression of cKrox and S100A4 in CD4+CD8+ DPK thymocytes differentiation.","date":"2012","source":"Environmental toxicology and pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/22981438","citation_count":2,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7323,"output_tokens":2732,"usd":0.031475,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9928,"output_tokens":2861,"usd":0.060582,"stage2_stop_reason":"end_turn"},"total_usd":0.092057,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1996,\n      \"finding\": \"Genetic epistasis experiments in S. cerevisiae suggested SDS3 functions in a pathway related to, but potentially separable from, SIN3 and RPD3 in transcriptional silencing at HMR; sds3 mutations increase silencing at HML, HMR, and telomere-linked genes, similar to sin3 and rpd3 mutants, and SDS3 represses IME2 in haploid cells and is required for sporulation.\",\n      \"method\": \"Genetic screen for suppressors of defective silencing, epistasis analysis, reporter assays\",\n      \"journal\": \"Genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — genetic epistasis in yeast, single lab, no biochemical confirmation of complex membership\",\n      \"pmids\": [\"8978024\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Yeast Sds3p is an integral subunit of the high-molecular-weight Rpd3p·Sin3p histone deacetylase complex; in the absence of Sds3p, Sin3p and Rpd3p can be chromatographically separated, and the remaining Rpd3p complex has little or no HDAC activity, demonstrating that Sds3p is required for both complex integrity and catalytic activity.\",\n      \"method\": \"Biochemical fractionation (chromatography), co-immunoprecipitation, in vitro HDAC activity assay in sds3Δ yeast strain\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — biochemical reconstitution-level fractionation, HDAC activity assay, genetic deletion strain, replicated across labs\",\n      \"pmids\": [\"11024051\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Genetic analysis in S. cerevisiae demonstrates that SDS3 functions in the same genetic pathway as SIN3 and RPD3, and co-immunoprecipitation confirms that Sds3 is physically present in the Sin3 complex.\",\n      \"method\": \"Genetic epistasis analysis, co-immunoprecipitation\",\n      \"journal\": \"Genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal genetic and biochemical evidence, two orthogonal methods, single lab\",\n      \"pmids\": [\"10655212\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Mammalian Sds3 (mSds3) was identified as an integral component of the mSin3A/mSin3B-HDAC corepressor complex: it physically associates with mSin3 proteins in vivo, represses transcription in a partially HDAC-dependent manner, and is required to enable HDAC1 catalytic activity in vivo.\",\n      \"method\": \"Co-immunoprecipitation (in vivo association with mSin3), transcriptional repression assays, HDAC activity assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (Co-IP, transcription assay, HDAC activity assay), replicated functional parallel with yeast SDS3\",\n      \"pmids\": [\"11909966\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Human SDS3 undergoes endogenous Lys-63-linked (but not Lys-48-linked) polyubiquitination; the deubiquitinase USP17 physically interacts with SDS3 (shown by MALDI-TOF-MS, co-immunoprecipitation, and GST pull-down) and specifically removes Lys-63-linked ubiquitin chains from SDS3, which negatively regulates SDS3-associated HDAC activity.\",\n      \"method\": \"Co-immunoprecipitation, GST pull-down, MALDI-TOF-MS, ubiquitination linkage-specific assays, HDAC activity assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal biochemical methods (MS, Co-IP, GST pull-down, activity assay), single lab but rigorous\",\n      \"pmids\": [\"21239494\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"SDS3 contains hyaluronan binding motifs (HABMs) and directly binds hyaluronan (HA); deletion of HABMs in USP17 reduces its interaction with SDS3 but does not alter USP17's deubiquitinating activity toward SDS3 or USP17's functional regulation of SDS3-associated HDAC activity.\",\n      \"method\": \"CPC (cetylpyridinium chloride) binding assay, co-immunoprecipitation with HABM-deletion mutants, HDAC activity assay, soft agar/apoptosis/migration assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assay and mutagenesis with functional readout, single lab, two orthogonal methods\",\n      \"pmids\": [\"22662218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Knockdown of Suds3 in mouse blastocysts disrupts FGF4/ERK signaling, impairs trophectoderm proliferation, and abolishes primitive endoderm formation, establishing that Suds3/Sin3/HDAC complexes are required for early lineage specification; exogenous FGF4 rescues these defects.\",\n      \"method\": \"Suds3 knockdown in mouse preimplantation embryos, immunofluorescence for lineage markers, FGF4 rescue experiment, HDAC1 knockdown comparison\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with specific molecular rescue, two knockdown conditions, single lab\",\n      \"pmids\": [\"23123966\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"SDS3 associates with ARNT (in a TCDD ligand-specific, but not B(a)P-specific, manner) as part of the Sin3/HDAC repressor complex, and reduction of SDS3 protein de-represses cKrox and S100A4 expression in CD4+CD8+ DPK thymocytes, placing SDS3 in AhR/ARNT ligand-specific transcriptional repression.\",\n      \"method\": \"Co-immunoprecipitation with anti-ARNT antibody, SDS3 protein knockdown, gene expression analysis\",\n      \"journal\": \"Environmental toxicology and pharmacology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP and knockdown, single lab, limited mechanistic follow-up\",\n      \"pmids\": [\"22981438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Solution NMR revealed that the Sds3 Sin3 interaction domain (SID) samples two discrete conformations with lifetimes in the tens of milliseconds range, differing by a 5–7 Å translation of the main chain; Sds3 engages Sin3A via a bipartite motif within the SID comprising a helix and an extended segment, and Sds3 provides a homodimerization activity required for assembly of the 1–2 MDa Sin3L/Rpd3L complex.\",\n      \"method\": \"Solution NMR spectroscopy with functional validation of conformational exchange\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — NMR structural data, single lab, limited mutagenesis/functional follow-up reported in abstract\",\n      \"pmids\": [\"26522936\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SDS3 modulates expression of ASK1, the upstream kinase of the p38 MAPK pathway, in microglia, thereby regulating p38 MAPK signaling activation and microglial inflammatory responses; SDS3 target genes were identified by chromatin immunoprecipitation combined with transcriptomics and proteomics.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP), SDS3 knockdown, transcriptomics, proteomics, downstream pathway validation\",\n      \"journal\": \"Inflammation research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP plus multi-omics with functional validation, single lab, two orthogonal approaches\",\n      \"pmids\": [\"39008037\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"SUDS3 over-expression in BRMS1-non-expressing metastatic breast cancer cells did not suppress metastasis, motility, osteopontin secretion, or EGF receptor expression, demonstrating that SUDS3 and BRMS1 have functionally distinct roles within SIN3-HDAC complexes despite structural relatedness.\",\n      \"method\": \"SUDS3 over-expression in metastatic cell lines, motility assays, soft agar assay, EGF receptor expression analysis\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple functional assays, negative result mechanistically informative, single lab\",\n      \"pmids\": [\"19070953\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SUDS3/SDS3 is an integral, conserved subunit of the Sin3/HDAC corepressor complex that homodimerizes and engages Sin3A via a bipartite SID motif (resolved by NMR), is essential for the physical integrity of the complex and for HDAC1/2 catalytic activity, represses transcription at specific target genes (including ASK1) through chromatin deacetylation, undergoes Lys-63-linked polyubiquitination that is removed by the deubiquitinase USP17 to negatively regulate HDAC activity, and in early mammalian development is required for FGF4/ERK signaling and lineage specification.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SUDS3/SDS3 is a conserved, integral subunit of the Sin3/Rpd3(HDAC) corepressor complex that is essential for both the physical integrity of the complex and its histone deacetylase catalytic output [#1, #3]. First defined genetically in yeast as a factor acting in the same transcriptional-silencing pathway as SIN3 and RPD3 [#0, #2], Sds3 was shown by chromatographic fractionation to be required to hold Sin3 and Rpd3 together; loss of Sds3 separates the subunits and abolishes HDAC activity [#1]. The mammalian ortholog associates with mSin3A/mSin3B in vivo, represses transcription in an HDAC-dependent manner, and is required to enable HDAC1 catalytic activity [#3]. Structurally, Sds3 engages Sin3A through a bipartite Sin3-interaction domain (SID) comprising a helix and an extended segment that samples two discrete conformations, and provides a homodimerization activity needed to assemble the 1\\u20132 MDa Sin3L/Rpd3L complex [#8]. SDS3-associated HDAC activity is negatively regulated by a ubiquitin switch: SDS3 carries Lys-63-linked polyubiquitin chains that the deubiquitinase USP17 removes through a direct physical interaction [#4]. Through chromatin deacetylation at specific targets, SDS3 represses genes including ASK1 to control p38 MAPK signaling and microglial inflammatory responses [#9], and is required in early mouse development for FGF4/ERK-dependent lineage specification [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Established that SDS3 acts in transcriptional silencing alongside SIN3 and RPD3, raising the question of whether it is a dedicated component of the same machinery.\",\n      \"evidence\": \"Suppressor genetic screen and epistasis with reporter assays in S. cerevisiae\",\n      \"pmids\": [\"8978024\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Genetic only \\u2014 no biochemical demonstration of complex membership\", \"Did not show whether SDS3 is required for HDAC activity\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Defined the core mechanistic role of Sds3 by showing it is physically required to hold the Rpd3\\u00b7Sin3 complex together and to sustain its deacetylase activity.\",\n      \"evidence\": \"Chromatographic fractionation, Co-IP, and in vitro HDAC assays in sds3\\u0394 yeast; complemented by reciprocal genetic/Co-IP analysis\",\n      \"pmids\": [\"11024051\", \"10655212\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of how Sds3 bridges Sin3 and Rpd3 not resolved\", \"Conducted in yeast \\u2014 mammalian relevance not yet shown\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Extended the function to mammals, establishing mSds3 as an integral Sin3A/B-HDAC subunit required for HDAC1 catalytic activity in vivo.\",\n      \"evidence\": \"Co-IP with mSin3, transcriptional repression assays, and HDAC activity assays in mammalian cells\",\n      \"pmids\": [\"11909966\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific target genes in mammals not defined\", \"Domain mediating Sin3 contact not mapped\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identified a post-translational control of SDS3-associated HDAC activity, showing K63-linked ubiquitination of SDS3 is reversed by USP17 to tune deacetylase output.\",\n      \"evidence\": \"Co-IP, GST pull-down, MALDI-TOF-MS, linkage-specific ubiquitination and HDAC activity assays\",\n      \"pmids\": [\"21239494\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"E3 ligase adding the K63 chains not identified\", \"Site of ubiquitination on SDS3 not mapped\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Resolved the molecular interface and oligomeric requirement, showing SDS3 binds Sin3A via a bipartite SID and homodimerizes to assemble the megadalton Sin3L/Rpd3L complex.\",\n      \"evidence\": \"Solution NMR spectroscopy with conformational-exchange analysis\",\n      \"pmids\": [\"26522936\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Limited mutagenesis/functional validation of the dimerization interface\", \"No full complex structure\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Connected SDS3 to specific physiological repression programs, including ligand-specific AhR/ARNT repression and a non-canonical hyaluronan-binding activity.\",\n      \"evidence\": \"Co-IP with ARNT plus knockdown in thymocytes; CPC hyaluronan binding and HABM-deletion assays\",\n      \"pmids\": [\"22981438\", \"22662218\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"ARNT association rests on single Co-IP and knockdown without reciprocal validation\", \"Functional consequence of hyaluronan binding unresolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Placed SDS3 in a developmental program, showing it is required for FGF4/ERK signaling and primitive endoderm lineage specification in early mouse embryos.\",\n      \"evidence\": \"Suds3 knockdown in mouse blastocysts with lineage-marker immunofluorescence and FGF4 rescue\",\n      \"pmids\": [\"23123966\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct transcriptional targets mediating FGF4 regulation not identified\", \"Single-lab knockdown without genetic null\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified direct SDS3 target genes, showing repression of ASK1 controls p38 MAPK activation and microglial inflammation.\",\n      \"evidence\": \"ChIP combined with transcriptomics/proteomics, SDS3 knockdown, and downstream pathway validation\",\n      \"pmids\": [\"39008037\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether ASK1 regulation generalizes beyond microglia unknown\", \"Recruitment of the complex to the ASK1 locus not defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SDS3 recruitment, its ubiquitin switch, and its bipartite Sin3 interface are integrated to direct target-gene selection across tissues remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"E3 ligase and ubiquitination sites unmapped\", \"Genome-wide target catalog incomplete\", \"No integrated structure of the assembled complex\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 3, 9]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [1, 3, 4]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1, 3, 9]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [1, 3]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [3, 9]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"complexes\": [\n      \"Sin3/HDAC corepressor complex\",\n      \"Rpd3L (Sin3L) histone deacetylase complex\"\n    ],\n    \"partners\": [\n      \"SIN3A\",\n      \"SIN3B\",\n      \"HDAC1\",\n      \"USP17\",\n      \"ARNT\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}