{"gene":"RNASEH2C","run_date":"2026-06-10T06:43:37","timeline":{"discoveries":[{"year":2008,"finding":"Human RNase H2 is a heterotrimeric complex composed of RNASEH2A (catalytic subunit), RNASEH2B, and RNASEH2C. RNASEH2B and RNASEH2C form a soluble B/C sub-complex that serves as a nucleation site for addition of the catalytic RNASEH2A subunit. RNASEH2C contributes to enzymatic activity, as the AGS-associated R69W mutation in RNASEH2C causes a significant reduction in specific activity, while four other AGS-related mutations in RNASEH2B and RNASEH2C showed near-normal activity.","method":"Biochemical reconstitution of the heterotrimeric complex, in vitro enzymatic activity assays, analysis of AGS-associated mutant proteins","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of complex, direct enzymatic activity assays with mutant proteins, multiple orthogonal biochemical methods in a single rigorous study","pmids":["19015152"],"is_preprint":false},{"year":2008,"finding":"RNASEH2C (together with RNASEH2B) forms a B/C sub-complex independent of the catalytic subunit RNASEH2A, suggesting a scaffolding/nucleation role for RNASEH2C in assembly of the active RNase H2 trimer.","method":"Biochemical fractionation and complex reconstitution in vitro","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct biochemical reconstitution demonstrating B/C sub-complex formation, single lab with multiple orthogonal methods","pmids":["19015152"],"is_preprint":false},{"year":2019,"finding":"Rnaseh2c functions as a metastasis susceptibility factor in breast cancer independently of RNase H2 enzymatic activity. shRNA-mediated knockdown of Rnaseh2c reduced metastasis, and the mechanism involved engagement of T cell-mediated adaptive immune response rather than cGAS-STING pathway activation.","method":"shRNA-mediated gene knockdown in mouse metastasis models, immunophenotyping, RNA-sequencing, haplotype mapping strategy","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KD with defined cellular phenotype, multiple methods (immunophenotyping + RNA-seq) but single lab; enzymatic independence inferred rather than directly tested by reconstitution","pmids":["31125342"],"is_preprint":false},{"year":2023,"finding":"The RNASEH2C variant c.434G>T (p.Arg145Leu) destabilizes local protein structure (as assessed by crystal structure simulation) and leads to protein degradation in vitro, establishing a loss-of-function mechanism for this AGS3-causing mutation.","method":"In vitro expression of variant plasmid, protein crystal structure simulation","journal":"Zhonghua yi xue yi chuan xue za zhi","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, in vitro expression assay plus computational structural modeling; no reconstitution or mutagenesis with functional rescue","pmids":["36585007"],"is_preprint":false},{"year":2025,"finding":"RNASEH2C in macrophages promotes lysosomal degradation of the scaffold protein RAI14 by enhancing TRAF3IP1 expression and suppressing the mTOR pathway, thereby inhibiting MHC II-mediated macropinocytosis and antigen presentation, which in turn reduces Th1 cell activation and promotes hepatocellular carcinoma growth.","method":"In vitro cell models, mouse tumor models, immunoblotting, immunofluorescence, co-immunoprecipitation, flow cytometry, single-cell RNA sequencing","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP plus multiple orthogonal methods (immunoblotting, immunofluorescence, flow cytometry) in a single lab; functional rescue not reported in the abstract","pmids":["41361104"],"is_preprint":false},{"year":2026,"finding":"RNASEH2C acts as a non-enzymatic regulator in proliferating macrophages by binding directly to cyclin-dependent kinase promoters (including CDK1/CDK9) to drive macrophage proliferation and suppress antigen-presenting capability, and promotes CD8+ exhausted T cell infiltration via the CCL2/CCR2 axis to foster an immunosuppressive tumor microenvironment in HCC.","method":"Single-cell RNA sequencing, CUT&Tag, bulk RNA sequencing, multiparametric immunofluorescence, flow cytometry, molecular dynamics simulation","journal":"Journal for immunotherapy of cancer","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, novel claims about chromatin binding from CUT&Tag without direct reconstitution or mutagenesis; abstract does not describe full mechanistic rescue experiments","pmids":["41986071"],"is_preprint":false}],"current_model":"RNASEH2C is a non-catalytic scaffolding subunit of the heterotrimeric RNase H2 complex that forms a B/C sub-complex with RNASEH2B to nucleate assembly of the active RNASEH2A-containing trimer; it contributes to enzymatic activity (the R69W AGS mutation reduces activity), and independently of its enzymatic role it acts as a scaffold in macrophages to regulate lysosomal degradation of RAI14 via TRAF3IP1/mTOR, suppress antigen presentation, and drive macrophage proliferation through CDK promoter binding, with its loss also reducing breast cancer metastasis through T cell-mediated immunity."},"narrative":{"mechanistic_narrative":"RNASEH2C is a non-catalytic subunit of the heterotrimeric RNase H2 ribonuclease, where it partners with RNASEH2B to form a soluble B/C sub-complex that nucleates assembly of the active trimer upon addition of the catalytic RNASEH2A subunit [PMID:19015152]. Although it lacks catalytic activity itself, RNASEH2C contributes to enzymatic function, as the Aicardi-Goutières syndrome (AGS3)-associated R69W mutation significantly reduces RNase H2 specific activity [PMID:19015152], and the AGS3-causing p.Arg145Leu variant destabilizes the protein and drives its degradation, defining a loss-of-function disease mechanism [PMID:36585007]. Independent of its role in the RNase H2 complex, RNASEH2C functions as a regulator of macrophage biology and tumor immunity: in macrophages it promotes lysosomal degradation of the scaffold protein RAI14 via enhanced TRAF3IP1 expression and mTOR suppression, restraining MHC II-mediated antigen presentation and Th1 activation [PMID:41361104], and it acts as a non-enzymatic chromatin-associated factor that binds cyclin-dependent kinase promoters (CDK1/CDK9) to drive macrophage proliferation while fostering an immunosuppressive microenvironment [PMID:41986071]. Consistent with an immune-modulatory role, loss of Rnaseh2c reduces breast cancer metastasis through engagement of T cell-mediated adaptive immunity rather than cGAS-STING signaling [PMID:31125342].","teleology":[{"year":2008,"claim":"Established the architecture of human RNase H2 and defined RNASEH2C's role as a scaffolding subunit, answering how the active enzyme assembles and why RNASEH2C matters despite lacking catalysis.","evidence":"Biochemical reconstitution of the heterotrimer and in vitro activity assays with AGS-associated mutant proteins","pmids":["19015152"],"confidence":"High","gaps":["Structural basis of how RNASEH2C contributes to catalytic activity not resolved","Why R69W reduces activity while other AGS mutations are near-normal unexplained"]},{"year":2019,"claim":"Revealed an enzyme-independent role for RNASEH2C in cancer, showing it acts as a metastasis susceptibility factor through adaptive immunity rather than its nuclease function.","evidence":"shRNA knockdown in mouse breast cancer metastasis models with immunophenotyping and RNA-seq","pmids":["31125342"],"confidence":"Medium","gaps":["Enzymatic independence inferred, not directly tested by reconstitution","Molecular target/mechanism linking RNASEH2C to T cell response not identified"]},{"year":2023,"claim":"Defined the molecular consequence of a specific AGS3-causing variant, showing it acts by protein destabilization and degradation.","evidence":"In vitro expression of the p.Arg145Leu variant and crystal structure simulation","pmids":["36585007"],"confidence":"Low","gaps":["No functional rescue or reconstitution to confirm loss-of-function","Computational structural modeling not validated experimentally"]},{"year":2025,"claim":"Connected RNASEH2C to a defined signaling axis in macrophages, showing it suppresses antigen presentation by promoting RAI14 degradation via TRAF3IP1/mTOR.","evidence":"In vitro cell models, mouse tumor models, reciprocal co-IP, immunoblotting, flow cytometry, scRNA-seq","pmids":["41361104"],"confidence":"Medium","gaps":["Functional rescue not reported","Direct physical interaction map among RNASEH2C, TRAF3IP1, and RAI14 incompletely defined"]},{"year":2026,"claim":"Proposed a chromatin-associated, non-enzymatic role in which RNASEH2C binds CDK promoters to drive macrophage proliferation and shape an immunosuppressive microenvironment.","evidence":"Single-cell RNA-seq, CUT&Tag, bulk RNA-seq, multiparametric immunofluorescence, flow cytometry, molecular dynamics simulation","pmids":["41986071"],"confidence":"Low","gaps":["Chromatin binding claim from CUT&Tag lacks reconstitution or mutagenesis","Direct DNA-binding capacity of RNASEH2C not biochemically demonstrated","No rescue experiments described"]},{"year":null,"claim":"How RNASEH2C's canonical scaffolding role in the RNase H2 nuclease relates mechanistically to its enzyme-independent functions in macrophage proliferation, chromatin binding, and tumor immunity remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural or biochemical link between the nuclear nuclease role and the immune-regulatory roles","Whether chromatin/promoter binding is direct and sequence-specific is undetermined","No reconstitution distinguishing enzymatic from non-enzymatic functions in immune cells"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1]}],"localization":[],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,4]}],"complexes":["RNase H2"],"partners":["RNASEH2B","RNASEH2A","TRAF3IP1","RAI14"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8TDP1","full_name":"Ribonuclease H2 subunit C","aliases":["Aicardi-Goutieres syndrome 3 protein","AGS3","RNase H1 small subunit","Ribonuclease HI subunit C"],"length_aa":164,"mass_kda":17.8,"function":"Non catalytic subunit of RNase H2, an endonuclease that specifically degrades the RNA of RNA:DNA hybrids. Participates in DNA replication, possibly by mediating the removal of lagging-strand Okazaki fragment RNA primers during DNA replication. Mediates the excision of single ribonucleotides from DNA:RNA duplexes","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q8TDP1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RNASEH2C","classification":"Not Classified","n_dependent_lines":352,"n_total_lines":1208,"dependency_fraction":0.2913907284768212},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"RNASEH2A","stoichiometry":10.0},{"gene":"PKMYT1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/RNASEH2C","total_profiled":1310},"omim":[{"mim_id":"610448","title":"CHILBLAIN LUPUS 1; CHBL1","url":"https://www.omim.org/entry/610448"},{"mim_id":"610330","title":"RIBONUCLEASE H2, SUBUNIT C; RNASEH2C","url":"https://www.omim.org/entry/610330"},{"mim_id":"610329","title":"AICARDI-GOUTIERES SYNDROME 3; AGS3","url":"https://www.omim.org/entry/610329"},{"mim_id":"610326","title":"RIBONUCLEASE H2, SUBUNIT B; RNASEH2B","url":"https://www.omim.org/entry/610326"},{"mim_id":"606754","title":"SAM DOMAIN- AND HD DOMAIN-CONTAINING PROTEIN 1; SAMHD1","url":"https://www.omim.org/entry/606754"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/RNASEH2C"},"hgnc":{"alias_symbol":["AYP1","AGS3"],"prev_symbol":[]},"alphafold":{"accession":"Q8TDP1","domains":[{"cath_id":"2.40.128.680","chopping":"13-87_117-157","consensus_level":"high","plddt":95.0628,"start":13,"end":157}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TDP1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TDP1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TDP1-F1-predicted_aligned_error_v6.png","plddt_mean":85.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RNASEH2C","jax_strain_url":"https://www.jax.org/strain/search?query=RNASEH2C"},"sequence":{"accession":"Q8TDP1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TDP1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TDP1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TDP1"}},"corpus_meta":[{"pmid":"25604658","id":"PMC_25604658","title":"Characterization of human disease phenotypes associated with mutations in TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR, and IFIH1.","date":"2015","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/25604658","citation_count":507,"is_preprint":false},{"pmid":"24183309","id":"PMC_24183309","title":"Assessment of interferon-related biomarkers in Aicardi-Goutières syndrome associated with mutations in TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, and ADAR: a case-control study.","date":"2013","source":"The Lancet. Neurology","url":"https://pubmed.ncbi.nlm.nih.gov/24183309","citation_count":371,"is_preprint":false},{"pmid":"19015152","id":"PMC_19015152","title":"Contributions of the two accessory subunits, RNASEH2B and RNASEH2C, to the activity and properties of the human RNase H2 complex.","date":"2008","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/19015152","citation_count":112,"is_preprint":false},{"pmid":"23322642","id":"PMC_23322642","title":"Striking intrafamilial phenotypic variability in Aicardi-Goutières syndrome associated with the recurrent Asian founder mutation in RNASEH2C.","date":"2013","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/23322642","citation_count":29,"is_preprint":false},{"pmid":"31125342","id":"PMC_31125342","title":"Aicardi-Goutières syndrome gene Rnaseh2c is a metastasis susceptibility gene in breast cancer.","date":"2019","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/31125342","citation_count":15,"is_preprint":false},{"pmid":"29150899","id":"PMC_29150899","title":"p.Arg69Trp in RNASEH2C is a founder variant in three Indian families with Aicardi-Goutières syndrome.","date":"2017","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/29150899","citation_count":7,"is_preprint":false},{"pmid":"27411419","id":"PMC_27411419","title":"Clinical and neuroradiologic variability of Aicardi-Goutiéres syndrome: Two siblings with RNASEH2C mutation and a boy with TREX1 mutation.","date":"2015","source":"The Turkish journal of pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/27411419","citation_count":5,"is_preprint":false},{"pmid":"33681774","id":"PMC_33681774","title":"Novel RNASEH2C mutation in multiple members of a large family: insights into phenotypic spectrum of Aicardi-Goutières Syndrome.","date":"2020","source":"BMJ neurology open","url":"https://pubmed.ncbi.nlm.nih.gov/33681774","citation_count":2,"is_preprint":false},{"pmid":"41361104","id":"PMC_41361104","title":"RNASEH2C enhances TRAF3IP1 to degrade RAI14 in lysosomes thus hindering macrophage antigen presentation and advancing liver cancer.","date":"2025","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/41361104","citation_count":1,"is_preprint":false},{"pmid":"37092250","id":"PMC_37092250","title":"RNASEH2C c.194G>A is a Chinese-specific founder mutation in three unrelated patients with Aicardi-Goutières syndrome 3.","date":"2023","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/37092250","citation_count":1,"is_preprint":false},{"pmid":"36585007","id":"PMC_36585007","title":"[Clinical report and genetic analysis of a child with Aicardi-Goutières syndrome type 3 due to compound heterozygous variants of RNASEH2C gene].","date":"2023","source":"Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36585007","citation_count":1,"is_preprint":false},{"pmid":"41986071","id":"PMC_41986071","title":"Non-enzymatic Rnaseh2c orchestrates proliferating macrophage-driven immunosuppression and HCC progression via Cdk9 proliferation axis and CCL2/CCR2-mediated CD8+ Tex infiltration: a novel therapeutic paradigm with \"Rnaseh2c-In1\" inhibitor.","date":"2026","source":"Journal for immunotherapy of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/41986071","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8299,"output_tokens":1625,"usd":0.024636,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8482,"output_tokens":2151,"usd":0.048093,"stage2_stop_reason":"end_turn"},"total_usd":0.072729,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2008,\n      \"finding\": \"Human RNase H2 is a heterotrimeric complex composed of RNASEH2A (catalytic subunit), RNASEH2B, and RNASEH2C. RNASEH2B and RNASEH2C form a soluble B/C sub-complex that serves as a nucleation site for addition of the catalytic RNASEH2A subunit. RNASEH2C contributes to enzymatic activity, as the AGS-associated R69W mutation in RNASEH2C causes a significant reduction in specific activity, while four other AGS-related mutations in RNASEH2B and RNASEH2C showed near-normal activity.\",\n      \"method\": \"Biochemical reconstitution of the heterotrimeric complex, in vitro enzymatic activity assays, analysis of AGS-associated mutant proteins\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of complex, direct enzymatic activity assays with mutant proteins, multiple orthogonal biochemical methods in a single rigorous study\",\n      \"pmids\": [\"19015152\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"RNASEH2C (together with RNASEH2B) forms a B/C sub-complex independent of the catalytic subunit RNASEH2A, suggesting a scaffolding/nucleation role for RNASEH2C in assembly of the active RNase H2 trimer.\",\n      \"method\": \"Biochemical fractionation and complex reconstitution in vitro\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct biochemical reconstitution demonstrating B/C sub-complex formation, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"19015152\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Rnaseh2c functions as a metastasis susceptibility factor in breast cancer independently of RNase H2 enzymatic activity. shRNA-mediated knockdown of Rnaseh2c reduced metastasis, and the mechanism involved engagement of T cell-mediated adaptive immune response rather than cGAS-STING pathway activation.\",\n      \"method\": \"shRNA-mediated gene knockdown in mouse metastasis models, immunophenotyping, RNA-sequencing, haplotype mapping strategy\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KD with defined cellular phenotype, multiple methods (immunophenotyping + RNA-seq) but single lab; enzymatic independence inferred rather than directly tested by reconstitution\",\n      \"pmids\": [\"31125342\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The RNASEH2C variant c.434G>T (p.Arg145Leu) destabilizes local protein structure (as assessed by crystal structure simulation) and leads to protein degradation in vitro, establishing a loss-of-function mechanism for this AGS3-causing mutation.\",\n      \"method\": \"In vitro expression of variant plasmid, protein crystal structure simulation\",\n      \"journal\": \"Zhonghua yi xue yi chuan xue za zhi\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, in vitro expression assay plus computational structural modeling; no reconstitution or mutagenesis with functional rescue\",\n      \"pmids\": [\"36585007\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"RNASEH2C in macrophages promotes lysosomal degradation of the scaffold protein RAI14 by enhancing TRAF3IP1 expression and suppressing the mTOR pathway, thereby inhibiting MHC II-mediated macropinocytosis and antigen presentation, which in turn reduces Th1 cell activation and promotes hepatocellular carcinoma growth.\",\n      \"method\": \"In vitro cell models, mouse tumor models, immunoblotting, immunofluorescence, co-immunoprecipitation, flow cytometry, single-cell RNA sequencing\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP plus multiple orthogonal methods (immunoblotting, immunofluorescence, flow cytometry) in a single lab; functional rescue not reported in the abstract\",\n      \"pmids\": [\"41361104\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"RNASEH2C acts as a non-enzymatic regulator in proliferating macrophages by binding directly to cyclin-dependent kinase promoters (including CDK1/CDK9) to drive macrophage proliferation and suppress antigen-presenting capability, and promotes CD8+ exhausted T cell infiltration via the CCL2/CCR2 axis to foster an immunosuppressive tumor microenvironment in HCC.\",\n      \"method\": \"Single-cell RNA sequencing, CUT&Tag, bulk RNA sequencing, multiparametric immunofluorescence, flow cytometry, molecular dynamics simulation\",\n      \"journal\": \"Journal for immunotherapy of cancer\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, novel claims about chromatin binding from CUT&Tag without direct reconstitution or mutagenesis; abstract does not describe full mechanistic rescue experiments\",\n      \"pmids\": [\"41986071\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RNASEH2C is a non-catalytic scaffolding subunit of the heterotrimeric RNase H2 complex that forms a B/C sub-complex with RNASEH2B to nucleate assembly of the active RNASEH2A-containing trimer; it contributes to enzymatic activity (the R69W AGS mutation reduces activity), and independently of its enzymatic role it acts as a scaffold in macrophages to regulate lysosomal degradation of RAI14 via TRAF3IP1/mTOR, suppress antigen presentation, and drive macrophage proliferation through CDK promoter binding, with its loss also reducing breast cancer metastasis through T cell-mediated immunity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RNASEH2C is a non-catalytic subunit of the heterotrimeric RNase H2 ribonuclease, where it partners with RNASEH2B to form a soluble B/C sub-complex that nucleates assembly of the active trimer upon addition of the catalytic RNASEH2A subunit [#0, #1]. Although it lacks catalytic activity itself, RNASEH2C contributes to enzymatic function, as the Aicardi-Goutières syndrome (AGS3)-associated R69W mutation significantly reduces RNase H2 specific activity [#0], and the AGS3-causing p.Arg145Leu variant destabilizes the protein and drives its degradation, defining a loss-of-function disease mechanism [#3]. Independent of its role in the RNase H2 complex, RNASEH2C functions as a regulator of macrophage biology and tumor immunity: in macrophages it promotes lysosomal degradation of the scaffold protein RAI14 via enhanced TRAF3IP1 expression and mTOR suppression, restraining MHC II-mediated antigen presentation and Th1 activation [#4], and it acts as a non-enzymatic chromatin-associated factor that binds cyclin-dependent kinase promoters (CDK1/CDK9) to drive macrophage proliferation while fostering an immunosuppressive microenvironment [#5]. Consistent with an immune-modulatory role, loss of Rnaseh2c reduces breast cancer metastasis through engagement of T cell-mediated adaptive immunity rather than cGAS-STING signaling [#2].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established the architecture of human RNase H2 and defined RNASEH2C's role as a scaffolding subunit, answering how the active enzyme assembles and why RNASEH2C matters despite lacking catalysis.\",\n      \"evidence\": \"Biochemical reconstitution of the heterotrimer and in vitro activity assays with AGS-associated mutant proteins\",\n      \"pmids\": [\"19015152\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of how RNASEH2C contributes to catalytic activity not resolved\", \"Why R69W reduces activity while other AGS mutations are near-normal unexplained\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Revealed an enzyme-independent role for RNASEH2C in cancer, showing it acts as a metastasis susceptibility factor through adaptive immunity rather than its nuclease function.\",\n      \"evidence\": \"shRNA knockdown in mouse breast cancer metastasis models with immunophenotyping and RNA-seq\",\n      \"pmids\": [\"31125342\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Enzymatic independence inferred, not directly tested by reconstitution\", \"Molecular target/mechanism linking RNASEH2C to T cell response not identified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined the molecular consequence of a specific AGS3-causing variant, showing it acts by protein destabilization and degradation.\",\n      \"evidence\": \"In vitro expression of the p.Arg145Leu variant and crystal structure simulation\",\n      \"pmids\": [\"36585007\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No functional rescue or reconstitution to confirm loss-of-function\", \"Computational structural modeling not validated experimentally\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected RNASEH2C to a defined signaling axis in macrophages, showing it suppresses antigen presentation by promoting RAI14 degradation via TRAF3IP1/mTOR.\",\n      \"evidence\": \"In vitro cell models, mouse tumor models, reciprocal co-IP, immunoblotting, flow cytometry, scRNA-seq\",\n      \"pmids\": [\"41361104\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional rescue not reported\", \"Direct physical interaction map among RNASEH2C, TRAF3IP1, and RAI14 incompletely defined\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Proposed a chromatin-associated, non-enzymatic role in which RNASEH2C binds CDK promoters to drive macrophage proliferation and shape an immunosuppressive microenvironment.\",\n      \"evidence\": \"Single-cell RNA-seq, CUT&Tag, bulk RNA-seq, multiparametric immunofluorescence, flow cytometry, molecular dynamics simulation\",\n      \"pmids\": [\"41986071\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Chromatin binding claim from CUT&Tag lacks reconstitution or mutagenesis\", \"Direct DNA-binding capacity of RNASEH2C not biochemically demonstrated\", \"No rescue experiments described\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How RNASEH2C's canonical scaffolding role in the RNase H2 nuclease relates mechanistically to its enzyme-independent functions in macrophage proliferation, chromatin binding, and tumor immunity remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural or biochemical link between the nuclear nuclease role and the immune-regulatory roles\", \"Whether chromatin/promoter binding is direct and sequence-specific is undetermined\", \"No reconstitution distinguishing enzymatic from non-enzymatic functions in immune cells\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 4]}\n    ],\n    \"complexes\": [\"RNase H2\"],\n    \"partners\": [\"RNASEH2B\", \"RNASEH2A\", \"TRAF3IP1\", \"RAI14\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":3,"faith_total":4,"faith_pct":75.0}}