{"gene":"MTNAP1","run_date":"2026-06-10T05:19:51","timeline":{"discoveries":[{"year":2023,"finding":"C17orf80/MTNAP1 localizes to mitochondrial nucleoid foci and exhibits robust double-stranded DNA binding activity throughout the mitochondrial genome, constituting a bona fide mitochondrial nucleoid protein that promotes mtDNA replication and controls mtDNA copy number levels.","method":"Immunofluorescence microscopy, DNA binding assays, mtDNA quantification after knockdown/knockout, functional metabolic assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct localization with functional consequence, in vitro DNA binding assay, and loss-of-function with specific phenotypic readout (reduced mtDNA levels, impaired mitochondrial metabolism), all in a single focused study","pmids":["37676315"],"is_preprint":false},{"year":2023,"finding":"C17orf80/MTNAP1 is a mitochondrial membrane-associated protein that interacts with nucleoids even when mtDNA replication is inhibited; however, it was found NOT essential for mtDNA maintenance or mitochondrial gene expression in cultured human cells.","method":"Immunofluorescence microscopy, interaction proteomics (proximity labeling MS), biochemical fractionation, genetic knockdown/knockout assays","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal localization and interaction proteomics in a single lab with multiple orthogonal methods; notable that this paper reports negative/null results for essentiality, partially contradicting PMID:37676315","pmids":["37401363"],"is_preprint":false},{"year":2026,"finding":"Loss-of-function variants in MTNAP1 (p.G553R and p.Y13X) cause mitochondrial fragmentation, reduced oxidative phosphorylation, increased reactive oxygen species, and premature senescence in proband-derived fibroblasts and MTNAP1-silenced neuronal cells; structural modeling and biophysical analyses showed the p.G553R variant destabilizes the MTNAP1 fold, disrupts its DNA- and membrane-binding interfaces, and induces aberrant protein aggregation.","method":"Patient fibroblast functional studies, siRNA knockdown in neuronal cells, structural modeling, biophysical analyses (protein stability/aggregation assays), mitochondrial morphology and OXPHOS capacity measurements","journal":"NPJ genomic medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — loss-of-function with specific mitochondrial phenotypes and structural modeling; single lab, structural conclusions from modeling not crystal/cryo-EM structure","pmids":["41720819"],"is_preprint":false}],"current_model":"MTNAP1 (C17orf80) is a mitochondrial nucleoid-associated protein that binds double-stranded DNA throughout the mitochondrial genome, promotes mtDNA replication and copy number maintenance, and is required for mitochondrial membrane integrity, oxidative phosphorylation, and prevention of mitochondrial fragmentation; loss-of-function variants cause a progressive neurodegenerative disorder in humans."},"narrative":{"mechanistic_narrative":"MTNAP1 (C17orf80) is a mitochondrial nucleoid-associated protein that links the mitochondrial genome to the integrity of the organelle [PMID:37676315]. It localizes to mitochondrial nucleoid foci, binds double-stranded DNA across the mitochondrial genome, and promotes mtDNA replication and copy-number maintenance [PMID:37676315]. MTNAP1 is also membrane-associated and remains attached to nucleoids when mtDNA replication is blocked, indicating that its nucleoid association is independent of ongoing replication [PMID:37401363]. In humans, loss-of-function variants (p.G553R and p.Y13X) cause mitochondrial fragmentation, reduced oxidative phosphorylation, elevated reactive oxygen species, and premature senescence, defining MTNAP1 deficiency as the basis of a mitochondrial disorder; structural modeling indicates the p.G553R substitution destabilizes the fold and disrupts the DNA- and membrane-binding interfaces while promoting aggregation [PMID:41720819]. One study using cultured human cells reported that MTNAP1 is not essential for mtDNA maintenance or mitochondrial gene expression, indicating that the severity of its requirement is cell-context dependent [PMID:37401363]. Beyond these findings, no further mechanistic detail has been characterized in the available corpus.","teleology":[{"year":2023,"claim":"Established that MTNAP1 is a genuine mitochondrial nucleoid protein with a functional role, answering whether this uncharacterized ORF participates in mtDNA biology.","evidence":"Immunofluorescence, in vitro dsDNA binding assays, and mtDNA quantification after knockdown/knockout in human cells","pmids":["37676315"],"confidence":"High","gaps":["No structural basis for DNA binding determined","Mechanism by which it promotes replication (e.g., interaction with replisome) not defined","Sequence specificity of genome-wide DNA binding not resolved"]},{"year":2023,"claim":"Tested whether MTNAP1 is essential for mtDNA maintenance and gene expression, finding it dispensable in cultured human cells and replication-independent in its nucleoid association.","evidence":"Proximity-labeling interaction proteomics, biochemical fractionation, and knockdown/knockout assays in cultured human cells","pmids":["37401363"],"confidence":"Medium","gaps":["Negative essentiality result partially contradicts the concurrent replication/copy-number phenotype","Direct binding partners within nucleoids not firmly identified","Cell-type dependence of the requirement not resolved"]},{"year":2026,"claim":"Connected MTNAP1 loss-of-function to a human mitochondrial disease phenotype and rationalized variant pathogenicity structurally, establishing physiological importance beyond cultured cell lines.","evidence":"Patient fibroblast functional studies, siRNA knockdown in neuronal cells, structural modeling and protein biophysics, mitochondrial morphology and OXPHOS measurements","pmids":["41720819"],"confidence":"Medium","gaps":["Structural conclusions from modeling rather than experimental crystal/cryo-EM structure","Single-lab patient cohort","Mechanistic link from DNA/membrane-binding loss to fragmentation and senescence not directly demonstrated"]},{"year":null,"claim":"How MTNAP1 mechanistically couples nucleoid/DNA binding and membrane association to mtDNA replication and prevention of mitochondrial fragmentation, and why essentiality differs across cell contexts, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No high-resolution structure of MTNAP1 or its DNA complex","Direct protein partners at the nucleoid not defined","Reconciliation of dispensability versus copy-number/replication phenotypes lacking"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0,1,2]}],"pathway":[{"term_id":"R-HSA-69306","term_label":"DNA Replication","supporting_discovery_ids":[0]}],"complexes":["mitochondrial nucleoid"],"partners":[],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BSJ5","full_name":"Mitochondrial nucleoid-associated protein 1","aliases":["Cell migration-inducing gene 3 protein","Human lung cancer oncogene 8 protein","HLC-8","Protein C17orf80"],"length_aa":609,"mass_kda":67.3,"function":"Critical regulator of mitochondrial DNA (mtDNA) abundance (PubMed:37676315). Binds dsDNA throughout the mitochondrial genome without sequence specificity and controls mtDNA copy number by promoting its replication (PubMed:37676315). Also plays important roles in mitochondrial metabolism and cell proliferation (PubMed:37676315)","subcellular_location":"Mitochondrion inner membrane; Mitochondrion matrix, mitochondrion nucleoid","url":"https://www.uniprot.org/uniprotkb/Q9BSJ5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MTNAP1","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":[{"gene":"FARP1","stoichiometry":4.0},{"gene":"CAPZB","stoichiometry":0.2},{"gene":"HIST2H2BE","stoichiometry":0.2},{"gene":"HSPA1B","stoichiometry":0.2},{"gene":"PSPC1","stoichiometry":0.2},{"gene":"SRP9","stoichiometry":0.2},{"gene":"TOP1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/MTNAP1","total_profiled":1310},"omim":[{"mim_id":"620717","title":"MITOCHONDRIAL NUCLEOID-ASSOCIATED PROTEIN 1; MTNAP1","url":"https://www.omim.org/entry/620717"}],"hpa":{"profiled":true,"resolved_as":"C17ORF80","reliability":"Approved","locations":[{"location":"Mitochondria","reliability":"Approved"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/C17ORF80"},"hgnc":{"alias_symbol":["HLC-8","MIG3","FLJ20721","SPEP1"],"prev_symbol":["C17orf80"]},"alphafold":{"accession":"Q9BSJ5","domains":[{"cath_id":"-","chopping":"2-33","consensus_level":"medium","plddt":82.1525,"start":2,"end":33}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BSJ5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BSJ5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BSJ5-F1-predicted_aligned_error_v6.png","plddt_mean":44.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MTNAP1","jax_strain_url":"https://www.jax.org/strain/search?query=MTNAP1"},"sequence":{"accession":"Q9BSJ5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BSJ5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BSJ5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BSJ5"}},"corpus_meta":[{"pmid":"14993292","id":"PMC_14993292","title":"The protein kinase Snf1 is required for tolerance to the ribonucleotide reductase inhibitor hydroxyurea.","date":"2004","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/14993292","citation_count":45,"is_preprint":false},{"pmid":"29441126","id":"PMC_29441126","title":"Association of improved oxidative stress tolerance and alleviation of glucose repression with superior xylose-utilization capability by a natural isolate of Saccharomyces cerevisiae.","date":"2018","source":"Biotechnology for biofuels","url":"https://pubmed.ncbi.nlm.nih.gov/29441126","citation_count":25,"is_preprint":false},{"pmid":"21327160","id":"PMC_21327160","title":"The Rad23 ubiquitin receptor, the proteasome and functional specificity in transcriptional control.","date":"2010","source":"Transcription","url":"https://pubmed.ncbi.nlm.nih.gov/21327160","citation_count":23,"is_preprint":false},{"pmid":"35318442","id":"PMC_35318442","title":"HNF4A-AS1-encoded small peptide promotes self-renewal and aggressiveness of neuroblastoma stem cells via eEF1A1-repressed SMAD4 transactivation.","date":"2022","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/35318442","citation_count":22,"is_preprint":false},{"pmid":"31667368","id":"PMC_31667368","title":"Benchmarking two Saccharomyces cerevisiae laboratory strains for growth and transcriptional response to methanol.","date":"2019","source":"Synthetic and systems biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/31667368","citation_count":21,"is_preprint":false},{"pmid":"25868388","id":"PMC_25868388","title":"Yes-mediated phosphorylation of focal adhesion kinase at tyrosine 861 increases metastatic potential of prostate cancer cells.","date":"2015","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/25868388","citation_count":19,"is_preprint":false},{"pmid":"34693526","id":"PMC_34693526","title":"Root cortex development is fine-tuned by the interplay of MIGs, SCL3 and DELLAs during arbuscular mycorrhizal symbiosis.","date":"2021","source":"The New phytologist","url":"https://pubmed.ncbi.nlm.nih.gov/34693526","citation_count":16,"is_preprint":false},{"pmid":"12065698","id":"PMC_12065698","title":"Effect of albumin and cytosol on enzyme kinetics of tolbutamide hydroxylation and on inhibition of CYP2C9 by gemfibrozil in human liver microsomes.","date":"2002","source":"The Journal of pharmacology and experimental therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/12065698","citation_count":16,"is_preprint":false},{"pmid":"28285895","id":"PMC_28285895","title":"Transcriptomic analysis of basidiocarp development in Ustilago maydis (DC) Cda.","date":"2017","source":"Fungal genetics and biology : FG & B","url":"https://pubmed.ncbi.nlm.nih.gov/28285895","citation_count":11,"is_preprint":false},{"pmid":"25163837","id":"PMC_25163837","title":"Synthetic lethal screen of NAA20, a catalytic subunit gene of NatB N-terminal acetylase in Saccharomyces cerevisiae.","date":"2014","source":"Journal of microbiology (Seoul, Korea)","url":"https://pubmed.ncbi.nlm.nih.gov/25163837","citation_count":5,"is_preprint":false},{"pmid":"35803529","id":"PMC_35803529","title":"New discovery of high-affinity SARS-CoV-2 spike S2 protein binding peptide selected by PhIP-Seq.","date":"2022","source":"Virologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/35803529","citation_count":3,"is_preprint":false},{"pmid":"37676315","id":"PMC_37676315","title":"C17orf80 binds the mitochondrial genome to promote its replication.","date":"2023","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/37676315","citation_count":2,"is_preprint":false},{"pmid":"37401363","id":"PMC_37401363","title":"Uncharacterized protein C17orf80 - a novel interactor of human mitochondrial nucleoids.","date":"2023","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/37401363","citation_count":1,"is_preprint":false},{"pmid":"41720819","id":"PMC_41720819","title":"Variants in MTNAP1 underlie a neurodegenerative disorder by impairing mitochondrial stability.","date":"2026","source":"NPJ genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/41720819","citation_count":0,"is_preprint":false},{"pmid":"12725029","id":"PMC_12725029","title":"[K-ras gene mutations of asbestos and welding-fumes related human lung cancer].","date":"2000","source":"Wei sheng yan jiu = Journal of hygiene research","url":"https://pubmed.ncbi.nlm.nih.gov/12725029","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8801,"output_tokens":863,"usd":0.019674,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7391,"output_tokens":1648,"usd":0.039078,"stage2_stop_reason":"end_turn"},"total_usd":0.058752,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2023,\n      \"finding\": \"C17orf80/MTNAP1 localizes to mitochondrial nucleoid foci and exhibits robust double-stranded DNA binding activity throughout the mitochondrial genome, constituting a bona fide mitochondrial nucleoid protein that promotes mtDNA replication and controls mtDNA copy number levels.\",\n      \"method\": \"Immunofluorescence microscopy, DNA binding assays, mtDNA quantification after knockdown/knockout, functional metabolic assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization with functional consequence, in vitro DNA binding assay, and loss-of-function with specific phenotypic readout (reduced mtDNA levels, impaired mitochondrial metabolism), all in a single focused study\",\n      \"pmids\": [\"37676315\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"C17orf80/MTNAP1 is a mitochondrial membrane-associated protein that interacts with nucleoids even when mtDNA replication is inhibited; however, it was found NOT essential for mtDNA maintenance or mitochondrial gene expression in cultured human cells.\",\n      \"method\": \"Immunofluorescence microscopy, interaction proteomics (proximity labeling MS), biochemical fractionation, genetic knockdown/knockout assays\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal localization and interaction proteomics in a single lab with multiple orthogonal methods; notable that this paper reports negative/null results for essentiality, partially contradicting PMID:37676315\",\n      \"pmids\": [\"37401363\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Loss-of-function variants in MTNAP1 (p.G553R and p.Y13X) cause mitochondrial fragmentation, reduced oxidative phosphorylation, increased reactive oxygen species, and premature senescence in proband-derived fibroblasts and MTNAP1-silenced neuronal cells; structural modeling and biophysical analyses showed the p.G553R variant destabilizes the MTNAP1 fold, disrupts its DNA- and membrane-binding interfaces, and induces aberrant protein aggregation.\",\n      \"method\": \"Patient fibroblast functional studies, siRNA knockdown in neuronal cells, structural modeling, biophysical analyses (protein stability/aggregation assays), mitochondrial morphology and OXPHOS capacity measurements\",\n      \"journal\": \"NPJ genomic medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — loss-of-function with specific mitochondrial phenotypes and structural modeling; single lab, structural conclusions from modeling not crystal/cryo-EM structure\",\n      \"pmids\": [\"41720819\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MTNAP1 (C17orf80) is a mitochondrial nucleoid-associated protein that binds double-stranded DNA throughout the mitochondrial genome, promotes mtDNA replication and copy number maintenance, and is required for mitochondrial membrane integrity, oxidative phosphorylation, and prevention of mitochondrial fragmentation; loss-of-function variants cause a progressive neurodegenerative disorder in humans.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MTNAP1 (C17orf80) is a mitochondrial nucleoid-associated protein that links the mitochondrial genome to the integrity of the organelle [#0]. It localizes to mitochondrial nucleoid foci, binds double-stranded DNA across the mitochondrial genome, and promotes mtDNA replication and copy-number maintenance [#0]. MTNAP1 is also membrane-associated and remains attached to nucleoids when mtDNA replication is blocked, indicating that its nucleoid association is independent of ongoing replication [#1]. In humans, loss-of-function variants (p.G553R and p.Y13X) cause mitochondrial fragmentation, reduced oxidative phosphorylation, elevated reactive oxygen species, and premature senescence, defining MTNAP1 deficiency as the basis of a mitochondrial disorder; structural modeling indicates the p.G553R substitution destabilizes the fold and disrupts the DNA- and membrane-binding interfaces while promoting aggregation [#2]. One study using cultured human cells reported that MTNAP1 is not essential for mtDNA maintenance or mitochondrial gene expression, indicating that the severity of its requirement is cell-context dependent [#1]. Beyond these findings, no further mechanistic detail has been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2023,\n      \"claim\": \"Established that MTNAP1 is a genuine mitochondrial nucleoid protein with a functional role, answering whether this uncharacterized ORF participates in mtDNA biology.\",\n      \"evidence\": \"Immunofluorescence, in vitro dsDNA binding assays, and mtDNA quantification after knockdown/knockout in human cells\",\n      \"pmids\": [\"37676315\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structural basis for DNA binding determined\", \"Mechanism by which it promotes replication (e.g., interaction with replisome) not defined\", \"Sequence specificity of genome-wide DNA binding not resolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Tested whether MTNAP1 is essential for mtDNA maintenance and gene expression, finding it dispensable in cultured human cells and replication-independent in its nucleoid association.\",\n      \"evidence\": \"Proximity-labeling interaction proteomics, biochemical fractionation, and knockdown/knockout assays in cultured human cells\",\n      \"pmids\": [\"37401363\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Negative essentiality result partially contradicts the concurrent replication/copy-number phenotype\", \"Direct binding partners within nucleoids not firmly identified\", \"Cell-type dependence of the requirement not resolved\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Connected MTNAP1 loss-of-function to a human mitochondrial disease phenotype and rationalized variant pathogenicity structurally, establishing physiological importance beyond cultured cell lines.\",\n      \"evidence\": \"Patient fibroblast functional studies, siRNA knockdown in neuronal cells, structural modeling and protein biophysics, mitochondrial morphology and OXPHOS measurements\",\n      \"pmids\": [\"41720819\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural conclusions from modeling rather than experimental crystal/cryo-EM structure\", \"Single-lab patient cohort\", \"Mechanistic link from DNA/membrane-binding loss to fragmentation and senescence not directly demonstrated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How MTNAP1 mechanistically couples nucleoid/DNA binding and membrane association to mtDNA replication and prevention of mitochondrial fragmentation, and why essentiality differs across cell contexts, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No high-resolution structure of MTNAP1 or its DNA complex\", \"Direct protein partners at the nucleoid not defined\", \"Reconciliation of dispensability versus copy-number/replication phenotypes lacking\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"complexes\": [\"mitochondrial nucleoid\"],\n    \"partners\": [],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}