{"gene":"FAM120B","run_date":"2026-06-09T23:54:43","timeline":{"discoveries":[{"year":2018,"finding":"Human SAN1 (FAM120B) functions as a 5' exonuclease that acts independently of the Fanconi anemia (FA) pathway to confer resistance to interstrand DNA cross-links (ICLs); nuclease-dead SAN1 fails to rescue ICL sensitivity in SAN1-deleted HeLa cells and mouse embryonic fibroblasts, establishing that catalytic exonuclease activity is required for its function.","method":"CRISPR/Cas9 deletion, re-expression of wild-type vs. nuclease-dead SAN1, cell survival assays, chromosomal radial formation assays, epistasis with FANCD2","journal":"Nature Communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function rescue experiment with catalytic mutant in two independent cell models (HeLa and MEFs), multiple orthogonal phenotypic readouts (sensitivity, DNA damage markers, radial chromosomes)","pmids":["29968717"],"is_preprint":false},{"year":2018,"finding":"SAN1 (FAM120B) physically binds to Senataxin (SETX), an RNA/DNA helicase that resolves R-loops; this interaction is increased upon ICL-inducing treatment with Mitomycin C, and the SAN1–SETX interaction is required to prevent cross-link sensitivity, placing SAN1 in a pathway with SETX.","method":"Co-immunoprecipitation, Mitomycin C treatment, SAN1 deletion complementation assays","journal":"Nature Communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal binding demonstrated by Co-IP with functional epistasis in a single lab study","pmids":["29968717"],"is_preprint":false},{"year":2018,"finding":"SAN1 (FAM120B) deletion is not epistatic with FANCD2 (a core FA pathway component) for ICL sensitivity, establishing that SAN1 operates in an FA-independent pathway for ICL repair.","method":"Genetic epistasis analysis — double deletion/knockdown of SAN1 and FANCD2 combined with ICL sensitivity assays","journal":"Nature Communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean genetic epistasis with defined cellular phenotype, single lab","pmids":["29968717"],"is_preprint":false},{"year":2021,"finding":"Loss of San1 (FAM120B) in mice leads to excessive R-loop accumulation in neonatal cardiomyocyte nuclei, increased DNA damage (γH2AX), activation of ATR and PARP1 hyperactivity, G2/M cell-cycle arrest, and impaired cardiomyocyte proliferation, establishing a role for SAN1 in resolving R-loop-associated DNA damage in cardiomyocytes.","method":"CRISPR/Cas9 San1 knockout mice, S9.6 immunostaining for R-loops, γH2AX staining, cell cycle analysis, San1-/- AC16-cardiomyocyte cell line","journal":"Biochimica et Biophysica Acta. Molecular Basis of Disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with defined molecular and cellular phenotypes using multiple orthogonal readouts, single lab","pmids":["34339838"],"is_preprint":false}],"current_model":"Human FAM120B (SAN1) is a 5' exonuclease that physically associates with the R-loop-resolving helicase Senataxin (SETX) and operates in a Fanconi anemia-independent pathway to repair interstrand DNA cross-links; its catalytic exonuclease activity is essential for this function, and loss of SAN1 results in excessive R-loop accumulation, DNA damage, and impaired cell proliferation."},"narrative":{"mechanistic_narrative":"FAM120B (SAN1) is a 5' exonuclease that functions in genome maintenance by repairing interstrand DNA cross-links and resolving R-loop-associated DNA damage [PMID:29968717, PMID:34339838]. It acts in a Fanconi anemia-independent pathway, as its loss is not epistatic with FANCD2 for cross-link sensitivity, and its catalytic exonuclease activity is essential—a nuclease-dead variant fails to rescue cross-link sensitivity in SAN1-deleted cells [PMID:29968717]. SAN1 physically associates with the R-loop-resolving RNA/DNA helicase Senataxin (SETX), an interaction that increases upon cross-link induction and is required to prevent cross-link sensitivity, placing the two proteins in a common pathway [PMID:29968717]. Consistent with this role, loss of San1 in mice causes excessive R-loop accumulation, increased DNA damage, ATR and PARP1 activation, G2/M arrest, and impaired cell proliferation [PMID:34339838].","teleology":[{"year":2018,"claim":"Established that FAM120B/SAN1 is a catalytically active 5' exonuclease required for interstrand cross-link resistance, defining its core molecular function in genome maintenance.","evidence":"CRISPR/Cas9 deletion with wild-type versus nuclease-dead re-expression and cell survival/radial chromosome assays in HeLa cells and MEFs","pmids":["29968717"],"confidence":"High","gaps":["Direct biochemical demonstration of exonuclease activity on defined substrates not shown in the timeline","Step in cross-link repair at which the nuclease acts is undefined"]},{"year":2018,"claim":"Identified Senataxin as a physical partner of SAN1 whose interaction increases upon cross-link stress, linking SAN1 to R-loop resolution machinery.","evidence":"Reciprocal Co-immunoprecipitation with Mitomycin C treatment and deletion complementation assays","pmids":["29968717"],"confidence":"Medium","gaps":["Single-lab Co-IP; interaction interface and direct versus indirect binding unresolved","Whether SETX recruits SAN1 or vice versa not determined"]},{"year":2018,"claim":"Placed SAN1 in a Fanconi anemia-independent cross-link repair pathway through clean genetic epistasis with FANCD2.","evidence":"Genetic epistasis analysis combining SAN1 and FANCD2 loss with ICL sensitivity assays","pmids":["29968717"],"confidence":"Medium","gaps":["Other pathway components acting with SAN1 not identified","Mechanistic relationship to canonical FA-dependent repair undefined"]},{"year":2021,"claim":"Demonstrated in vivo that SAN1 loss drives R-loop accumulation and replication/DNA-damage stress, extending its role from cross-link repair to R-loop-associated damage resolution in a physiological tissue.","evidence":"CRISPR/Cas9 San1 knockout mice with S9.6 and gammaH2AX immunostaining, cell cycle analysis, and San1-/- AC16 cardiomyocyte line","pmids":["34339838"],"confidence":"Medium","gaps":["Whether R-loop accumulation is a direct consequence of lost nuclease activity or secondary to defective repair not resolved","Tissue specificity of the cardiomyocyte phenotype not explained"]},{"year":null,"claim":"How SAN1 exonuclease activity mechanistically couples to SETX-driven R-loop resolution and cross-link repair at the molecular level remains open.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of SAN1 or the SAN1-SETX complex","Direct nucleic acid substrate specificity not biochemically defined","Order of events in the FA-independent repair pathway unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140097","term_label":"catalytic activity, acting on DNA","supporting_discovery_ids":[0]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[0,3]}],"complexes":[],"partners":["SETX"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96EK7","full_name":"Constitutive coactivator of peroxisome proliferator-activated receptor gamma","aliases":["PPARG constitutive coactivator 1","PGCC1","Protein FAM120B"],"length_aa":910,"mass_kda":103.8,"function":"Functions as a transactivator of PPARG and ESR1. Functions in adipogenesis through PPARG activation (By similarity)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q96EK7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/FAM120B","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/FAM120B","total_profiled":1310},"omim":[{"mim_id":"618709","title":"NEURODEVELOPMENTAL DISORDER WITH NONSPECIFIC BRAIN ABNORMALITIES AND WITH OR WITHOUT SEIZURES; NEDBAS","url":"https://www.omim.org/entry/618709"},{"mim_id":"612266","title":"FAMILY WITH SEQUENCE SIMILARITY 120, MEMBER B; FAM120B","url":"https://www.omim.org/entry/612266"},{"mim_id":"606582","title":"DELTA-LIKE CANONICAL NOTCH LIGAND 1; DLL1","url":"https://www.omim.org/entry/606582"},{"mim_id":"300741","title":"FAMILY WITH SEQUENCE SIMILARITY 120, MEMBER C; FAM120C","url":"https://www.omim.org/entry/300741"}],"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/FAM120B"},"hgnc":{"alias_symbol":["PGCC1","CCPG","SAN1"],"prev_symbol":["KIAA1838"]},"alphafold":{"accession":"Q96EK7","domains":[{"cath_id":"3.40.50.1010","chopping":"7-93_125-304","consensus_level":"medium","plddt":91.8915,"start":7,"end":304},{"cath_id":"-","chopping":"575-859","consensus_level":"medium","plddt":93.002,"start":575,"end":859}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96EK7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96EK7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96EK7-F1-predicted_aligned_error_v6.png","plddt_mean":71.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=FAM120B","jax_strain_url":"https://www.jax.org/strain/search?query=FAM120B"},"sequence":{"accession":"Q96EK7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96EK7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96EK7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96EK7"}},"corpus_meta":[{"pmid":"20080635","id":"PMC_20080635","title":"Cytoplasmic protein quality control degradation mediated by parallel actions of the E3 ubiquitin ligases Ubr1 and San1.","date":"2009","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/20080635","citation_count":231,"is_preprint":false},{"pmid":"15078868","id":"PMC_15078868","title":"Sir Antagonist 1 (San1) is a ubiquitin ligase.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15078868","citation_count":40,"is_preprint":false},{"pmid":"31320219","id":"PMC_31320219","title":"The STING activator c-di-AMP exerts superior adjuvant properties than the formulation poly(I:C)/CpG after subcutaneous vaccination with soluble protein antigen or DEC-205-mediated antigen targeting to dendritic cells.","date":"2019","source":"Vaccine","url":"https://pubmed.ncbi.nlm.nih.gov/31320219","citation_count":38,"is_preprint":false},{"pmid":"8246972","id":"PMC_8246972","title":"The Saccharomyces cerevisiae Cdc68 transcription activator is antagonized by San1, a protein implicated in transcriptional silencing.","date":"1993","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/8246972","citation_count":34,"is_preprint":false},{"pmid":"21324894","id":"PMC_21324894","title":"Nuclear protein quality is regulated by the ubiquitin-proteasome system through the activity of Ubc4 and San1 in fission yeast.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21324894","citation_count":26,"is_preprint":false},{"pmid":"18248670","id":"PMC_18248670","title":"Genetic analysis of the spindle checkpoint genes san-1, mdf-2, bub-3 and the CENP-F homologues hcp-1 and hcp-2 in Caenorhabditis elegans.","date":"2008","source":"Cell division","url":"https://pubmed.ncbi.nlm.nih.gov/18248670","citation_count":22,"is_preprint":false},{"pmid":"29968717","id":"PMC_29968717","title":"A senataxin-associated exonuclease SAN1 is required for resistance to DNA interstrand cross-links.","date":"2018","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/29968717","citation_count":20,"is_preprint":false},{"pmid":"27173001","id":"PMC_27173001","title":"Molecular mass as a determinant for nuclear San1-dependent targeting of misfolded cytosolic proteins to proteasomal degradation.","date":"2016","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/27173001","citation_count":16,"is_preprint":false},{"pmid":"27405755","id":"PMC_27405755","title":"The San1 Ubiquitin Ligase Functions Preferentially with Ubiquitin-conjugating Enzyme Ubc1 during Protein Quality Control.","date":"2016","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/27405755","citation_count":12,"is_preprint":false},{"pmid":"34339838","id":"PMC_34339838","title":"San1 deficiency leads to cardiomyopathy due to excessive R-loop-associated DNA damage and cardiomyocyte hypoplasia.","date":"2021","source":"Biochimica et biophysica acta. Molecular basis of disease","url":"https://pubmed.ncbi.nlm.nih.gov/34339838","citation_count":9,"is_preprint":false},{"pmid":"34661445","id":"PMC_34661445","title":"Genome-Wide Regulations of the Preinitiation Complex Formation and Elongating RNA Polymerase II by an E3 Ubiquitin Ligase, San1.","date":"2021","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/34661445","citation_count":8,"is_preprint":false},{"pmid":"34827617","id":"PMC_34827617","title":"The San1 Ubiquitin Ligase Avidly Recognizes Misfolded Proteins through Multiple Substrate Binding Sites.","date":"2021","source":"Biomolecules","url":"https://pubmed.ncbi.nlm.nih.gov/34827617","citation_count":6,"is_preprint":false},{"pmid":"21211716","id":"PMC_21211716","title":"San1-mediated quality control: substrate recognition \"sans\" chaperones.","date":"2011","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/21211716","citation_count":5,"is_preprint":false},{"pmid":"39855624","id":"PMC_39855624","title":"TAP-MS analysis of FACT interactions and regulation by a ubiquitin ligase, San1.","date":"2025","source":"Biochimica et biophysica acta. Gene regulatory mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/39855624","citation_count":2,"is_preprint":false},{"pmid":"38302116","id":"PMC_38302116","title":"Role of the San1 ubiquitin ligase in the heat stress-induced degradation of nonnative Nup1 in the nuclear pore complex.","date":"2024","source":"Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38302116","citation_count":1,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.09.17.676868","title":"Aberrant cohesin function in  <i>Saccharomyces cerevisiae</i>  activates Mcd1 degradation to promote cell lethality","date":"2025-09-17","source":"bioRxiv","url":"https://doi.org/10.1101/2025.09.17.676868","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.06.29.601343","title":"Quiescent cells maintain active degradation-mediated protein quality control requiring proteasome, autophagy and nucleus-vacuole junctions","date":"2024-06-30","source":"bioRxiv","url":"https://doi.org/10.1101/2024.06.29.601343","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10150,"output_tokens":1525,"usd":0.026662,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7674,"output_tokens":1700,"usd":0.040435,"stage2_stop_reason":"end_turn"},"total_usd":0.067097,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"Looking at the corpus, I need to determine which papers are about the human/mammalian gene FAM120B (aliases: PGCC1, CCPG, SAN1, KIAA1838) versus other genes that share similar symbols.\n\nThe key distinction: FAM120B has the alias \"SAN1\" (human gene). However, the majority of papers in this corpus describe:\n- Yeast San1 (Saccharomyces cerevisiae/S. pombe) — a nuclear E3 ubiquitin ligase involved in protein quality control\n- C. elegans san-1 (MAD3 homologue, spindle checkpoint)\n- A human SAN1 described in paper [7] as a \"senataxin-associated exonuclease\"\n\nThe human FAM120B/SAN1 (KIAA1838) is described in paper [7] (Andrews et al., 2018, PMID:29968717) as a 5' exonuclease interacting with Senataxin involved in ICL repair — this is the canonical human protein. Paper [10] (Liu et al., 2021, PMID:34339838) also studies this human SAN1 in cardiomyocytes.\n\nThe yeast San1 papers are describing a DIFFERENT protein (yeast E3 ubiquitin ligase) — these are NOT orthologs of FAM120B/SAN1 (human exonuclease). The yeast San1 has RING domain E3 ligase activity, which is fundamentally incompatible with FAM120B being a 5' exonuclease. These are symbol collisions, not orthologs.\n\nPapers [7] and [10] describe the human FAM120B/SAN1 protein. All others describe yeast/worm San1 proteins that are unrelated.\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2018,\n      \"finding\": \"Human SAN1 (FAM120B) functions as a 5' exonuclease that acts independently of the Fanconi anemia (FA) pathway to confer resistance to interstrand DNA cross-links (ICLs); nuclease-dead SAN1 fails to rescue ICL sensitivity in SAN1-deleted HeLa cells and mouse embryonic fibroblasts, establishing that catalytic exonuclease activity is required for its function.\",\n      \"method\": \"CRISPR/Cas9 deletion, re-expression of wild-type vs. nuclease-dead SAN1, cell survival assays, chromosomal radial formation assays, epistasis with FANCD2\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function rescue experiment with catalytic mutant in two independent cell models (HeLa and MEFs), multiple orthogonal phenotypic readouts (sensitivity, DNA damage markers, radial chromosomes)\",\n      \"pmids\": [\"29968717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SAN1 (FAM120B) physically binds to Senataxin (SETX), an RNA/DNA helicase that resolves R-loops; this interaction is increased upon ICL-inducing treatment with Mitomycin C, and the SAN1–SETX interaction is required to prevent cross-link sensitivity, placing SAN1 in a pathway with SETX.\",\n      \"method\": \"Co-immunoprecipitation, Mitomycin C treatment, SAN1 deletion complementation assays\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal binding demonstrated by Co-IP with functional epistasis in a single lab study\",\n      \"pmids\": [\"29968717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SAN1 (FAM120B) deletion is not epistatic with FANCD2 (a core FA pathway component) for ICL sensitivity, establishing that SAN1 operates in an FA-independent pathway for ICL repair.\",\n      \"method\": \"Genetic epistasis analysis — double deletion/knockdown of SAN1 and FANCD2 combined with ICL sensitivity assays\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic epistasis with defined cellular phenotype, single lab\",\n      \"pmids\": [\"29968717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Loss of San1 (FAM120B) in mice leads to excessive R-loop accumulation in neonatal cardiomyocyte nuclei, increased DNA damage (γH2AX), activation of ATR and PARP1 hyperactivity, G2/M cell-cycle arrest, and impaired cardiomyocyte proliferation, establishing a role for SAN1 in resolving R-loop-associated DNA damage in cardiomyocytes.\",\n      \"method\": \"CRISPR/Cas9 San1 knockout mice, S9.6 immunostaining for R-loops, γH2AX staining, cell cycle analysis, San1-/- AC16-cardiomyocyte cell line\",\n      \"journal\": \"Biochimica et Biophysica Acta. Molecular Basis of Disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with defined molecular and cellular phenotypes using multiple orthogonal readouts, single lab\",\n      \"pmids\": [\"34339838\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"Human FAM120B (SAN1) is a 5' exonuclease that physically associates with the R-loop-resolving helicase Senataxin (SETX) and operates in a Fanconi anemia-independent pathway to repair interstrand DNA cross-links; its catalytic exonuclease activity is essential for this function, and loss of SAN1 results in excessive R-loop accumulation, DNA damage, and impaired cell proliferation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"FAM120B (SAN1) is a 5' exonuclease that functions in genome maintenance by repairing interstrand DNA cross-links and resolving R-loop-associated DNA damage [#0, #3]. It acts in a Fanconi anemia-independent pathway, as its loss is not epistatic with FANCD2 for cross-link sensitivity, and its catalytic exonuclease activity is essential—a nuclease-dead variant fails to rescue cross-link sensitivity in SAN1-deleted cells [#0, #2]. SAN1 physically associates with the R-loop-resolving RNA/DNA helicase Senataxin (SETX), an interaction that increases upon cross-link induction and is required to prevent cross-link sensitivity, placing the two proteins in a common pathway [#1]. Consistent with this role, loss of San1 in mice causes excessive R-loop accumulation, increased DNA damage, ATR and PARP1 activation, G2/M arrest, and impaired cell proliferation [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2018,\n      \"claim\": \"Established that FAM120B/SAN1 is a catalytically active 5' exonuclease required for interstrand cross-link resistance, defining its core molecular function in genome maintenance.\",\n      \"evidence\": \"CRISPR/Cas9 deletion with wild-type versus nuclease-dead re-expression and cell survival/radial chromosome assays in HeLa cells and MEFs\",\n      \"pmids\": [\"29968717\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct biochemical demonstration of exonuclease activity on defined substrates not shown in the timeline\", \"Step in cross-link repair at which the nuclease acts is undefined\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified Senataxin as a physical partner of SAN1 whose interaction increases upon cross-link stress, linking SAN1 to R-loop resolution machinery.\",\n      \"evidence\": \"Reciprocal Co-immunoprecipitation with Mitomycin C treatment and deletion complementation assays\",\n      \"pmids\": [\"29968717\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab Co-IP; interaction interface and direct versus indirect binding unresolved\", \"Whether SETX recruits SAN1 or vice versa not determined\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Placed SAN1 in a Fanconi anemia-independent cross-link repair pathway through clean genetic epistasis with FANCD2.\",\n      \"evidence\": \"Genetic epistasis analysis combining SAN1 and FANCD2 loss with ICL sensitivity assays\",\n      \"pmids\": [\"29968717\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Other pathway components acting with SAN1 not identified\", \"Mechanistic relationship to canonical FA-dependent repair undefined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrated in vivo that SAN1 loss drives R-loop accumulation and replication/DNA-damage stress, extending its role from cross-link repair to R-loop-associated damage resolution in a physiological tissue.\",\n      \"evidence\": \"CRISPR/Cas9 San1 knockout mice with S9.6 and gammaH2AX immunostaining, cell cycle analysis, and San1-/- AC16 cardiomyocyte line\",\n      \"pmids\": [\"34339838\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether R-loop accumulation is a direct consequence of lost nuclease activity or secondary to defective repair not resolved\", \"Tissue specificity of the cardiomyocyte phenotype not explained\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SAN1 exonuclease activity mechanistically couples to SETX-driven R-loop resolution and cross-link repair at the molecular level remains open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of SAN1 or the SAN1-SETX complex\", \"Direct nucleic acid substrate specificity not biochemically defined\", \"Order of events in the FA-independent repair pathway unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140097\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"SETX\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}