{"gene":"METTL23","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2014,"finding":"METTL23 protein localizes to both nucleus and cytoplasm, physically interacts with GABPA (GA-binding protein transcription factor alpha subunit), and functions as a transcriptional co-regulator: overexpression of METTL23 increased transcriptional activity at the THPO promoter, while siRNA knockdown reduced expression of ATP5B, establishing METTL23 as a regulator of GABPA-dependent transcription.","method":"Co-immunoprecipitation (physical interaction with GABPA), subcellular localization of overexpressed protein, luciferase/promoter reporter assay (THPO), siRNA knockdown with RT-PCR (ATP5B expression)","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — reciprocal interaction shown by Co-IP, functional transcriptional readout by two orthogonal methods (promoter reporter + knockdown), single lab","pmids":["24501276"],"is_preprint":false},{"year":2014,"finding":"Loss-of-function mutations in METTL23 that truncate the protein disrupt its predicted SAM-dependent methyltransferase catalytic domain and alter cellular localization, and expression analysis indicated a strong association with heat shock proteins as putative methylation substrates.","method":"Mutant protein 3D modelling, cellular localization assay of truncated vs. wild-type protein, co-expression/expression analysis","journal":"Human molecular genetics","confidence":"Low","confidence_rationale":"Tier 3–4 / Weak — localization data from mutant protein plus computational modelling; substrate association is correlative only, no direct methylation assay performed","pmids":["24626631"],"is_preprint":false},{"year":2017,"finding":"Maternal Mettl23 acts as a protein arginine methyltransferase (PRMT) that catalyzes asymmetric dimethylation of histone H3 at arginine 17 (H3R17me2a) in mouse zygotes, as established by in vitro methyltransferase assay and pharmacological inhibition with the H3R17 PRMT inhibitor TBBD.","method":"In vitro methyltransferase assay with recombinant Mettl23, PRMT inhibitor (TBBD) treatment, immunofluorescence for H3R17me2a in zygotes","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — in vitro enzymatic assay plus pharmacological validation in cells, single lab","pmids":["28930672"],"is_preprint":false},{"year":2017,"finding":"Mettl23 interacts with Tet3 (a 5mC-oxidizing enzyme) and the maternal factor GSE, forming a complex; depletion of Mettl23 from oocytes impaired accumulation of GSE, Tet3, and 5hmC in the male pronucleus, indicating that Mettl23-mediated H3R17me2a is required to recruit the GSE-Tet3 complex to chromatin for paternal genome active DNA demethylation.","method":"Co-immunoprecipitation (Mettl23-Tet3-GSE interaction), Mettl23 depletion in oocytes (RNAi/morpholino), immunofluorescence for GSE, Tet3, and 5hmC in male pronucleus","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP for complex membership, loss-of-function with specific cellular phenotype, single lab, multiple readouts","pmids":["28930672"],"is_preprint":false},{"year":2017,"finding":"METTL23 knockout in K562 cells did not result in any loss of eEF1A methylation, establishing that METTL23 is NOT the methyltransferase responsible for any of the tested eEF1A lysine methylation sites.","method":"CRISPR/Cas9 knockout of METTL23 in K562 cells, targeted mass spectrometry of eEF1A methylation","journal":"Molecular & cellular proteomics : MCP","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean CRISPR KO with targeted MS readout; this is a well-controlled negative result","pmids":["28663172"],"is_preprint":false},{"year":2022,"finding":"METTL23 catalyzes dimethylation of histone H3R17 in the retina; METTL23 deficiency (knock-in or knockout mice) reduced H3R17me2a and abolished transcription of pS2 (an estrogen receptor α target gene), leading to de-repression of NF-κB-mediated TNF-α and IL-1β signaling and retinal ganglion cell death, establishing a mechanistic pathway from H3R17 methylation to RGC homeostasis.","method":"Mettl23 knock-in and knockout mouse models, in vitro methyltransferase assay, immunofluorescence for H3R17me2a in retina, gene expression analysis (pS2, TNF-α, IL-1β), aberrant mRNA splicing and altered subcellular localization assay for mutant protein","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro enzymatic assay combined with multiple mouse genetic models (KI and KO), orthogonal molecular and cellular phenotyping in one study","pmids":["36099048"],"is_preprint":false},{"year":2026,"finding":"METTL23 physically interacts with JMJD6 in the nucleus upon pseudorabies virus (PRV) infection, suggesting a cooperative role in facilitating immune evasion; this interaction was identified by nuclear co-immunoprecipitation during viral infection.","method":"Co-immunoprecipitation of nuclear METTL23 with JMJD6 during PRV infection","journal":"Journal of virology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP experiment, no direct functional dissection of METTL23's individual contribution","pmids":["42053297"],"is_preprint":false}],"current_model":"METTL23 is an S-adenosyl-methionine-dependent protein arginine methyltransferase (PRMT) that catalyzes asymmetric dimethylation of histone H3 at arginine 17 (H3R17me2a); in zygotes this modification recruits the GSE–Tet3 complex to the paternal genome to enable active DNA demethylation, while in retinal ganglion cells it drives transcription of the pS2 gene to suppress NF-κB-mediated neuroinflammation, and in somatic cells METTL23 also acts as a transcriptional co-activator by binding the GABPA transcription factor to regulate downstream target genes."},"narrative":{"mechanistic_narrative":"METTL23 is an S-adenosyl-methionine-dependent protein arginine methyltransferase that catalyzes asymmetric dimethylation of histone H3 at arginine 17 (H3R17me2a) and thereby couples a chromatin mark to transcriptional and epigenetic programs in distinct cell types [PMID:28930672, PMID:36099048]. Its enzymatic activity toward H3R17 was demonstrated by in vitro methyltransferase assay with recombinant protein and confirmed by pharmacological inhibition in zygotes [PMID:28930672]. In the mouse zygote, maternal METTL23-generated H3R17me2a recruits the GSE–Tet3 5mC-oxidizing complex to the paternal genome, with which METTL23 physically associates, enabling 5hmC accumulation and active DNA demethylation of the male pronucleus [PMID:28930672]. In retinal ganglion cells, METTL23-dependent H3R17me2a drives transcription of the estrogen-receptor-α target gene pS2, and its loss de-represses NF-κB-mediated TNF-α/IL-1β signaling and causes RGC death, as established in knock-in and knockout mouse models [PMID:36099048]. Independently of histone methylation, METTL23 acts as a transcriptional co-regulator by physically binding the GABPA transcription factor to modulate downstream target genes such as THPO and ATP5B [PMID:24501276]. METTL23 is not the methyltransferase responsible for eEF1A lysine methylation [PMID:28663172].","teleology":[{"year":2014,"claim":"Established that METTL23 functions in transcription by physically partnering with a defined transcription factor rather than acting in isolation, framing it as a GABPA co-regulator.","evidence":"Co-IP with GABPA, THPO promoter reporter, and siRNA knockdown with RT-PCR of ATP5B in human cells","pmids":["24501276"],"confidence":"Medium","gaps":["Whether transcriptional co-regulation depends on methyltransferase activity was not tested","No catalytic substrate identified in this context"]},{"year":2014,"claim":"Linked truncating METTL23 mutations to disruption of the predicted SAM-dependent catalytic domain and altered localization, implicating loss of enzymatic function.","evidence":"3D modelling of mutant protein, localization assay of truncated vs wild-type protein, co-expression analysis","pmids":["24626631"],"confidence":"Low","gaps":["Heat shock protein substrate association is correlative with no direct methylation assay","Catalytic activity inferred from modelling only"]},{"year":2017,"claim":"Resolved METTL23's catalytic identity by showing it is a protein arginine methyltransferase that generates H3R17me2a, defining its substrate and mark.","evidence":"In vitro methyltransferase assay with recombinant Mettl23, TBBD inhibitor treatment, and H3R17me2a immunofluorescence in mouse zygotes","pmids":["28930672"],"confidence":"Medium","gaps":["Single lab; structural basis of arginine recognition not determined","Whether other arginine substrates exist not addressed"]},{"year":2017,"claim":"Connected the H3R17me2a mark to a downstream epigenetic outcome by showing METTL23 recruits the GSE–Tet3 complex for paternal genome demethylation.","evidence":"Co-IP of Mettl23–Tet3–GSE, oocyte depletion (RNAi/morpholino), and immunofluorescence for GSE, Tet3, and 5hmC in the male pronucleus","pmids":["28930672"],"confidence":"Medium","gaps":["Direct demonstration that H3R17me2a is the recruiting mark vs scaffolding role not separated","Single lab"]},{"year":2017,"claim":"Excluded eEF1A as a METTL23 substrate, sharpening its substrate specificity to histone arginine rather than non-histone lysine methylation.","evidence":"CRISPR/Cas9 knockout in K562 cells with targeted mass spectrometry of eEF1A methylation","pmids":["28663172"],"confidence":"Medium","gaps":["Negative result for one substrate does not enumerate the full substrate range"]},{"year":2022,"claim":"Demonstrated a physiological consequence of METTL23 catalysis in vivo: H3R17me2a drives pS2 transcription to restrain neuroinflammation and protect retinal ganglion cells.","evidence":"Mettl23 knock-in and knockout mice, in vitro methyltransferase assay, H3R17me2a immunofluorescence, and pS2/TNF-α/IL-1β expression analysis","pmids":["36099048"],"confidence":"High","gaps":["Mechanism linking pS2 to NF-κB suppression not fully resolved","Whether GABPA co-regulation contributes in retina not tested"]},{"year":2026,"claim":"Implicated METTL23 in a host–virus context through a nuclear interaction with JMJD6 during pseudorabies virus infection.","evidence":"Nuclear co-immunoprecipitation of METTL23 with JMJD6 during PRV infection","pmids":["42053297"],"confidence":"Low","gaps":["Single Co-IP without reciprocal validation","No functional dissection of METTL23's role in immune evasion","Catalytic relevance of the interaction unknown"]},{"year":null,"claim":"How METTL23 selects its substrates and whether its transcriptional co-activator role and its histone methyltransferase role are mechanistically unified remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of catalysis or substrate recognition","Relationship between GABPA co-regulation and H3R17 methylation untested","Full substrate repertoire undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[2,5]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2,5]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,6]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[2,5]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,5]}],"complexes":["GSE-Tet3 complex"],"partners":["GABPA","TET3","GSE","JMJD6"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q86XA0","full_name":"Histone-arginine methyltransferase METTL23","aliases":["Methyltransferase-like protein 23"],"length_aa":190,"mass_kda":21.5,"function":"Histone methyltransferase that dimethylates histone H3 at 'Arg-17', forming asymmetric dimethylarginine (H3R17me2a), leading to activate transcription via chromatin remodeling (By similarity). Maternal factor involved in epigenetic chromatin reprogramming of the paternal genome in the zygote: mediates H3R17me2a, promoting histone H3.3 incorporation in the male pronucleus, leading to TET3 recruitment and subsequent DNA demethylation (By similarity)","subcellular_location":"Nucleus; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q86XA0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/METTL23","classification":"Not Classified","n_dependent_lines":158,"n_total_lines":1208,"dependency_fraction":0.13079470198675497},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/METTL23","total_profiled":1310},"omim":[{"mim_id":"615942","title":"INTELLECTUAL DEVELOPMENTAL DISORDER, AUTOSOMAL RECESSIVE 44; MRT44","url":"https://www.omim.org/entry/615942"},{"mim_id":"615262","title":"METHYLTRANSFERASE-LIKE 23; METTL23","url":"https://www.omim.org/entry/615262"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/METTL23"},"hgnc":{"alias_symbol":["LOC124512"],"prev_symbol":["C17orf95"]},"alphafold":{"accession":"Q86XA0","domains":[{"cath_id":"3.40.50.150","chopping":"25-94","consensus_level":"medium","plddt":97.3199,"start":25,"end":94},{"cath_id":"-","chopping":"128-190","consensus_level":"medium","plddt":90.6467,"start":128,"end":190}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86XA0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q86XA0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q86XA0-F1-predicted_aligned_error_v6.png","plddt_mean":93.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=METTL23","jax_strain_url":"https://www.jax.org/strain/search?query=METTL23"},"sequence":{"accession":"Q86XA0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q86XA0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q86XA0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86XA0"}},"corpus_meta":[{"pmid":"28663172","id":"PMC_28663172","title":"METTL21B Is a Novel Human Lysine Methyltransferase of Translation Elongation Factor 1A: Discovery by CRISPR/Cas9 Knockout.","date":"2017","source":"Molecular & cellular proteomics : MCP","url":"https://pubmed.ncbi.nlm.nih.gov/28663172","citation_count":42,"is_preprint":false},{"pmid":"28930672","id":"PMC_28930672","title":"Histone H3 Methylated at Arginine 17 Is Essential for Reprogramming the Paternal Genome in Zygotes.","date":"2017","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/28930672","citation_count":40,"is_preprint":false},{"pmid":"24501276","id":"PMC_24501276","title":"METTL23, a transcriptional partner of GABPA, is essential for human cognition.","date":"2014","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24501276","citation_count":36,"is_preprint":false},{"pmid":"24626631","id":"PMC_24626631","title":"Disruption of the methyltransferase-like 23 gene METTL23 causes mild autosomal recessive intellectual disability.","date":"2014","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24626631","citation_count":28,"is_preprint":false},{"pmid":"36099048","id":"PMC_36099048","title":"METTL23 mutation alters histone H3R17 methylation in normal-tension glaucoma.","date":"2022","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/36099048","citation_count":26,"is_preprint":false},{"pmid":"33448881","id":"PMC_33448881","title":"Exome Sequencing and Congenital Heart Disease in Sub-Saharan Africa.","date":"2021","source":"Circulation. Genomic and precision medicine","url":"https://pubmed.ncbi.nlm.nih.gov/33448881","citation_count":23,"is_preprint":false},{"pmid":"38203567","id":"PMC_38203567","title":"Metabolic Pathway Engineering Improves Dendrobine Production in Dendrobium catenatum.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/38203567","citation_count":12,"is_preprint":false},{"pmid":"32439618","id":"PMC_32439618","title":"Exome sequencing revealed a novel homozygous METTL23 gene mutation leading to familial mild intellectual disability with dysmorphic features.","date":"2020","source":"European journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/32439618","citation_count":11,"is_preprint":false},{"pmid":"32067349","id":"PMC_32067349","title":"Further delineation of METTL23-associated intellectual disability.","date":"2020","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/32067349","citation_count":7,"is_preprint":false},{"pmid":"35581286","id":"PMC_35581286","title":"Identification of candidate genes associated with bacterial and viral infections in wild boars hunted in Tuscany (Italy).","date":"2022","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/35581286","citation_count":7,"is_preprint":false},{"pmid":"38389252","id":"PMC_38389252","title":"Molecular genetics of inherited normal tension glaucoma.","date":"2024","source":"Indian journal of ophthalmology","url":"https://pubmed.ncbi.nlm.nih.gov/38389252","citation_count":6,"is_preprint":false},{"pmid":"36317630","id":"PMC_36317630","title":"Epigenetics in glaucoma: a link between histone methylation and neurodegeneration.","date":"2022","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/36317630","citation_count":5,"is_preprint":false},{"pmid":"39202421","id":"PMC_39202421","title":"Association Analysis of METTL23 Gene Polymorphisms with Reproductive Traits in Kele Pigs.","date":"2024","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/39202421","citation_count":3,"is_preprint":false},{"pmid":"39325437","id":"PMC_39325437","title":"METTL23 Variants and Patients With Normal-Tension Glaucoma.","date":"2024","source":"JAMA ophthalmology","url":"https://pubmed.ncbi.nlm.nih.gov/39325437","citation_count":2,"is_preprint":false},{"pmid":"39026940","id":"PMC_39026940","title":"Identification of a novel METTL23 gene variant in a patient with an intellectual development disorder: a literature review and case report.","date":"2024","source":"Frontiers in pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/39026940","citation_count":2,"is_preprint":false},{"pmid":"42053297","id":"PMC_42053297","title":"JMJD6-mediated epigenetic silencing of innate immunity promotes pseudorabies virus replication.","date":"2026","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/42053297","citation_count":0,"is_preprint":false},{"pmid":"41809128","id":"PMC_41809128","title":"Emerging role of epigenetic mechanisms in glaucoma and their translational potential.","date":"2026","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/41809128","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10491,"output_tokens":1953,"usd":0.030384,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8810,"output_tokens":2607,"usd":0.054613,"stage2_stop_reason":"end_turn"},"total_usd":0.084997,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2014,\n      \"finding\": \"METTL23 protein localizes to both nucleus and cytoplasm, physically interacts with GABPA (GA-binding protein transcription factor alpha subunit), and functions as a transcriptional co-regulator: overexpression of METTL23 increased transcriptional activity at the THPO promoter, while siRNA knockdown reduced expression of ATP5B, establishing METTL23 as a regulator of GABPA-dependent transcription.\",\n      \"method\": \"Co-immunoprecipitation (physical interaction with GABPA), subcellular localization of overexpressed protein, luciferase/promoter reporter assay (THPO), siRNA knockdown with RT-PCR (ATP5B expression)\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — reciprocal interaction shown by Co-IP, functional transcriptional readout by two orthogonal methods (promoter reporter + knockdown), single lab\",\n      \"pmids\": [\"24501276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Loss-of-function mutations in METTL23 that truncate the protein disrupt its predicted SAM-dependent methyltransferase catalytic domain and alter cellular localization, and expression analysis indicated a strong association with heat shock proteins as putative methylation substrates.\",\n      \"method\": \"Mutant protein 3D modelling, cellular localization assay of truncated vs. wild-type protein, co-expression/expression analysis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3–4 / Weak — localization data from mutant protein plus computational modelling; substrate association is correlative only, no direct methylation assay performed\",\n      \"pmids\": [\"24626631\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Maternal Mettl23 acts as a protein arginine methyltransferase (PRMT) that catalyzes asymmetric dimethylation of histone H3 at arginine 17 (H3R17me2a) in mouse zygotes, as established by in vitro methyltransferase assay and pharmacological inhibition with the H3R17 PRMT inhibitor TBBD.\",\n      \"method\": \"In vitro methyltransferase assay with recombinant Mettl23, PRMT inhibitor (TBBD) treatment, immunofluorescence for H3R17me2a in zygotes\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro enzymatic assay plus pharmacological validation in cells, single lab\",\n      \"pmids\": [\"28930672\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Mettl23 interacts with Tet3 (a 5mC-oxidizing enzyme) and the maternal factor GSE, forming a complex; depletion of Mettl23 from oocytes impaired accumulation of GSE, Tet3, and 5hmC in the male pronucleus, indicating that Mettl23-mediated H3R17me2a is required to recruit the GSE-Tet3 complex to chromatin for paternal genome active DNA demethylation.\",\n      \"method\": \"Co-immunoprecipitation (Mettl23-Tet3-GSE interaction), Mettl23 depletion in oocytes (RNAi/morpholino), immunofluorescence for GSE, Tet3, and 5hmC in male pronucleus\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP for complex membership, loss-of-function with specific cellular phenotype, single lab, multiple readouts\",\n      \"pmids\": [\"28930672\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"METTL23 knockout in K562 cells did not result in any loss of eEF1A methylation, establishing that METTL23 is NOT the methyltransferase responsible for any of the tested eEF1A lysine methylation sites.\",\n      \"method\": \"CRISPR/Cas9 knockout of METTL23 in K562 cells, targeted mass spectrometry of eEF1A methylation\",\n      \"journal\": \"Molecular & cellular proteomics : MCP\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean CRISPR KO with targeted MS readout; this is a well-controlled negative result\",\n      \"pmids\": [\"28663172\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"METTL23 catalyzes dimethylation of histone H3R17 in the retina; METTL23 deficiency (knock-in or knockout mice) reduced H3R17me2a and abolished transcription of pS2 (an estrogen receptor α target gene), leading to de-repression of NF-κB-mediated TNF-α and IL-1β signaling and retinal ganglion cell death, establishing a mechanistic pathway from H3R17 methylation to RGC homeostasis.\",\n      \"method\": \"Mettl23 knock-in and knockout mouse models, in vitro methyltransferase assay, immunofluorescence for H3R17me2a in retina, gene expression analysis (pS2, TNF-α, IL-1β), aberrant mRNA splicing and altered subcellular localization assay for mutant protein\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro enzymatic assay combined with multiple mouse genetic models (KI and KO), orthogonal molecular and cellular phenotyping in one study\",\n      \"pmids\": [\"36099048\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"METTL23 physically interacts with JMJD6 in the nucleus upon pseudorabies virus (PRV) infection, suggesting a cooperative role in facilitating immune evasion; this interaction was identified by nuclear co-immunoprecipitation during viral infection.\",\n      \"method\": \"Co-immunoprecipitation of nuclear METTL23 with JMJD6 during PRV infection\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP experiment, no direct functional dissection of METTL23's individual contribution\",\n      \"pmids\": [\"42053297\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"METTL23 is an S-adenosyl-methionine-dependent protein arginine methyltransferase (PRMT) that catalyzes asymmetric dimethylation of histone H3 at arginine 17 (H3R17me2a); in zygotes this modification recruits the GSE–Tet3 complex to the paternal genome to enable active DNA demethylation, while in retinal ganglion cells it drives transcription of the pS2 gene to suppress NF-κB-mediated neuroinflammation, and in somatic cells METTL23 also acts as a transcriptional co-activator by binding the GABPA transcription factor to regulate downstream target genes.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"METTL23 is an S-adenosyl-methionine-dependent protein arginine methyltransferase that catalyzes asymmetric dimethylation of histone H3 at arginine 17 (H3R17me2a) and thereby couples a chromatin mark to transcriptional and epigenetic programs in distinct cell types [#2, #5]. Its enzymatic activity toward H3R17 was demonstrated by in vitro methyltransferase assay with recombinant protein and confirmed by pharmacological inhibition in zygotes [#2]. In the mouse zygote, maternal METTL23-generated H3R17me2a recruits the GSE\\u2013Tet3 5mC-oxidizing complex to the paternal genome, with which METTL23 physically associates, enabling 5hmC accumulation and active DNA demethylation of the male pronucleus [#2, #3]. In retinal ganglion cells, METTL23-dependent H3R17me2a drives transcription of the estrogen-receptor-\\u03b1 target gene pS2, and its loss de-represses NF-\\u03baB-mediated TNF-\\u03b1/IL-1\\u03b2 signaling and causes RGC death, as established in knock-in and knockout mouse models [#5]. Independently of histone methylation, METTL23 acts as a transcriptional co-regulator by physically binding the GABPA transcription factor to modulate downstream target genes such as THPO and ATP5B [#0]. METTL23 is not the methyltransferase responsible for eEF1A lysine methylation [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2014,\n      \"claim\": \"Established that METTL23 functions in transcription by physically partnering with a defined transcription factor rather than acting in isolation, framing it as a GABPA co-regulator.\",\n      \"evidence\": \"Co-IP with GABPA, THPO promoter reporter, and siRNA knockdown with RT-PCR of ATP5B in human cells\",\n      \"pmids\": [\"24501276\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether transcriptional co-regulation depends on methyltransferase activity was not tested\", \"No catalytic substrate identified in this context\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Linked truncating METTL23 mutations to disruption of the predicted SAM-dependent catalytic domain and altered localization, implicating loss of enzymatic function.\",\n      \"evidence\": \"3D modelling of mutant protein, localization assay of truncated vs wild-type protein, co-expression analysis\",\n      \"pmids\": [\"24626631\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Heat shock protein substrate association is correlative with no direct methylation assay\", \"Catalytic activity inferred from modelling only\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Resolved METTL23's catalytic identity by showing it is a protein arginine methyltransferase that generates H3R17me2a, defining its substrate and mark.\",\n      \"evidence\": \"In vitro methyltransferase assay with recombinant Mettl23, TBBD inhibitor treatment, and H3R17me2a immunofluorescence in mouse zygotes\",\n      \"pmids\": [\"28930672\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; structural basis of arginine recognition not determined\", \"Whether other arginine substrates exist not addressed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Connected the H3R17me2a mark to a downstream epigenetic outcome by showing METTL23 recruits the GSE\\u2013Tet3 complex for paternal genome demethylation.\",\n      \"evidence\": \"Co-IP of Mettl23\\u2013Tet3\\u2013GSE, oocyte depletion (RNAi/morpholino), and immunofluorescence for GSE, Tet3, and 5hmC in the male pronucleus\",\n      \"pmids\": [\"28930672\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct demonstration that H3R17me2a is the recruiting mark vs scaffolding role not separated\", \"Single lab\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Excluded eEF1A as a METTL23 substrate, sharpening its substrate specificity to histone arginine rather than non-histone lysine methylation.\",\n      \"evidence\": \"CRISPR/Cas9 knockout in K562 cells with targeted mass spectrometry of eEF1A methylation\",\n      \"pmids\": [\"28663172\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Negative result for one substrate does not enumerate the full substrate range\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated a physiological consequence of METTL23 catalysis in vivo: H3R17me2a drives pS2 transcription to restrain neuroinflammation and protect retinal ganglion cells.\",\n      \"evidence\": \"Mettl23 knock-in and knockout mice, in vitro methyltransferase assay, H3R17me2a immunofluorescence, and pS2/TNF-\\u03b1/IL-1\\u03b2 expression analysis\",\n      \"pmids\": [\"36099048\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking pS2 to NF-\\u03baB suppression not fully resolved\", \"Whether GABPA co-regulation contributes in retina not tested\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Implicated METTL23 in a host\\u2013virus context through a nuclear interaction with JMJD6 during pseudorabies virus infection.\",\n      \"evidence\": \"Nuclear co-immunoprecipitation of METTL23 with JMJD6 during PRV infection\",\n      \"pmids\": [\"42053297\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP without reciprocal validation\", \"No functional dissection of METTL23's role in immune evasion\", \"Catalytic relevance of the interaction unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How METTL23 selects its substrates and whether its transcriptional co-activator role and its histone methyltransferase role are mechanistically unified remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of catalysis or substrate recognition\", \"Relationship between GABPA co-regulation and H3R17 methylation untested\", \"Full substrate repertoire undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [2, 5]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2, 5]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 6]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [2, 5]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 5]}\n    ],\n    \"complexes\": [\"GSE-Tet3 complex\"],\n    \"partners\": [\"GABPA\", \"TET3\", \"GSE\", \"JMJD6\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}