{"gene":"MSS51","run_date":"2026-04-28T18:30:28","timeline":{"discoveries":[{"year":1990,"finding":"Mss51 (yeast) is specifically required for translation of the COX1 mRNA in yeast mitochondria, distinct from a splicing role; the paromomycin-resistance mutation in 15S mitoribosomal RNA interferes with Mss51 function, linking Mss51 action to the mitoribosome.","method":"Genetic analysis of mss51 mutants and paromomycin-resistance suppressor mutations in yeast mitochondria","journal":"Molecular & general genetics : MGG","confidence":"High","confidence_rationale":"Tier 2 — foundational genetic loss-of-function study, 84 citations, replicated in subsequent work","pmids":["2177521"],"is_preprint":false},{"year":2009,"finding":"Mss51 (yeast) has dual functions: it acts as a translational activator of COX1 mRNA via its 5'-UTR, and post-translationally it physically associates with newly synthesized, unassembled Cox1 protein in early cytochrome c oxidase assembly intermediates. Sequestration of Mss51 in these intermediates limits COX1 mRNA translation, coupling Cox1 synthesis to CcO assembly. Mss51 interaction with Cox1 requires Cox14, and Cox14-Cox1-Mss51 complex assembly depends on active Cox1 synthesis.","method":"Co-immunoprecipitation of Mss51 with Cox1 assembly intermediates, reporter gene assays, genetic analysis of cox14 and other assembly mutants in S. cerevisiae","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, reporter assays, multiple genetic epistasis tests, 79 citations","pmids":["19710419"],"is_preprint":false},{"year":2010,"finding":"Cox25, an inner mitochondrial membrane protein with a matrix-facing hydrophilic C-terminus, is an essential component of the Cox1-Ssc1-Mss51-Cox14 complex. Cox25 also interacts with Shy1 and Cox5 in a separate complex lacking Mss51, suggesting Cox25 bridges the Mss51-containing stabilization complex and downstream CcO assembly intermediates. Null mutation in Cox25 prevents Mss51 sequestration, similar to Cox14 null, and does not reduce Cox1 synthesis.","method":"Co-immunoprecipitation, subcellular fractionation, genetic epistasis analysis in S. cerevisiae","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, fractionation, multiple genetic backgrounds, 68 citations","pmids":["21068384"],"is_preprint":false},{"year":2015,"finding":"Mammalian MSS51 (ZMYND17) localizes to mitochondria in human skeletal muscle; CRISPR/Cas9-mediated disruption in C2C12 myoblasts increases cellular ATP, β-oxidation, glycolysis, and oxidative phosphorylation, indicating MSS51 negatively regulates mitochondrial metabolism.","method":"Subcellular fractionation/immunoblot for localization; CRISPR/Cas9 disruption with Seahorse metabolic assays, ATP measurement, and β-oxidation assays in C2C12 cells","journal":"Journal of neuromuscular diseases","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization by fractionation and KO with defined metabolic phenotype, single lab","pmids":["26634192"],"is_preprint":false},{"year":2018,"finding":"Zmynd17 (mouse ortholog of MSS51) is required for normal mitochondrial morphology and respiratory function in skeletal muscle; genetic inactivation causes mitochondrial structural and functional abnormalities and metabolic stress-induced hepatic steatosis and insulin resistance.","method":"Genetic knockout (Zmynd17-deficient mice), electron microscopy of mitochondrial morphology, oxygen consumption measurements, high-fat diet metabolic challenge","journal":"FASEB journal","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined cellular and systemic phenotypes, multiple orthogonal readouts, replicated by independent lab","pmids":["29913553"],"is_preprint":false},{"year":2019,"finding":"In Mss51-KO mice, isolated myofibers show increased oxygen consumption rate; skeletal muscle exhibits upregulation of oxidative phosphorylation and fatty acid β-oxidation gene expression. Mss51-KO mice on high-fat diet are resistant to obesity with increased whole-body glucose turnover, insulin sensitivity, and β-oxidation, confirming MSS51 as a negative regulator of skeletal muscle mitochondrial respiration in vivo.","method":"CRISPR/Cas9 Mss51-KO mice, Seahorse oxygen consumption rate on isolated myofibers, hyperinsulinemic-euglycemic clamp, metabolic phenotyping","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 — in vivo KO with multiple orthogonal metabolic readouts, independent replication of in vitro findings","pmids":["31527314"],"is_preprint":false},{"year":2019,"finding":"Zmynd17-mediated mitochondrial quality control in skeletal muscle is mechanistically distinct from PGC1α-induced mitochondrial biogenesis; PGC1α overexpression in Zmynd17-KO muscle exacerbates mitochondrial morphological abnormalities, and voluntary exercise improves mitochondrial morphology independently of Zmynd17 activity.","method":"Genetic epistasis: Zmynd17-KO mice with PGC1α overexpression, voluntary exercise protocol, electron microscopy of mitochondrial morphology","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 — epistasis with defined morphological readout, single lab","pmids":["31921843"],"is_preprint":false},{"year":2021,"finding":"Human ZMYND17 deletion does not affect mitochondrial translation but reduces cytochrome c oxidase activity and increases free F1 subunit of ATP synthase, demonstrating functional divergence from yeast Mss51p translational activator role.","method":"ZMYND17 gene deletion in human cells, mitochondrial translation assay, cytochrome c oxidase activity measurement, immunoblot for ATP synthase F1 subunit","journal":"Biochemistry. Biokhimiia","confidence":"Medium","confidence_rationale":"Tier 2 — KO with defined biochemical readouts, single lab, low citation count","pmids":["34565318"],"is_preprint":false},{"year":2023,"finding":"Site-1 protease (S1P) acts upstream of Mss51 to inhibit skeletal muscle mitochondrial respiration; S1P disruption in mouse skeletal muscle reduces Mss51 expression and increases mitochondrial respiration. Mss51 overexpression counteracts the increased respiration caused by S1P deficiency, placing Mss51 downstream of S1P in a TGF-β1 signaling pathway regulating muscle metabolism.","method":"Muscle-specific S1P knockout mice, Mss51 overexpression rescue experiment, oxygen consumption rate measurement, gene expression analysis","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis with rescue, defined metabolic phenotype, single lab","pmids":["37002920"],"is_preprint":false},{"year":2024,"finding":"YTHDF2 binds MSS51 mRNA (demonstrated by RNA immunoprecipitation) and reduces MSS51 expression; reduced MSS51 leads to mitochondrial damage, reduced ATP, increased ROS, and reduced expression of glycolysis genes (LDHA, PFKP, PKM) in granulosa cells.","method":"RNA immunoprecipitation (RIP) assay for YTHDF2-MSS51 mRNA binding, YTHDF2 overexpression and MSS51 knockdown with mitochondrial morphology imaging, ATP and ROS measurement, qPCR for glycolytic genes in human granulosa cells","journal":"Molecular and cellular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2-3 — RIP confirms direct RNA binding, functional readouts, single lab","pmids":["38830447"],"is_preprint":false},{"year":2024,"finding":"Betaine transcriptionally suppresses Mss51 via Yin Yang 1 (Yy1): Yy1 binds the Mss51 promoter (shown by ChIP and EMSA), suppressing Mss51 transcription; this restores Mss51-mediated suppression of mitochondrial respiration proteins and reduces superoxide in C2C12 cells and aging mouse muscle.","method":"Luciferase reporter assay, chromatin immunoprecipitation (ChIP), electrophoretic mobility shift assay (EMSA), AAV-mediated in vivo overexpression, Seahorse assay, immunofluorescence","journal":"Journal of cachexia, sarcopenia and muscle","confidence":"Medium","confidence_rationale":"Tier 1-2 — multiple orthogonal methods (ChIP, EMSA, reporter, in vivo rescue), single lab","pmids":["39187977"],"is_preprint":false},{"year":2024,"finding":"Yeast Mss51 and Pet309 both physically interact with the mitoribosome independently of COX1 mRNA and of each other; Pet309's association with the ribosome and with COX1 mRNA depends on its N-terminal domain. These stable mitoribosome interactions suggest that translational activators function by positioning the ribosome at the mRNA rather than solely through 5'-UTR binding.","method":"Co-immunoprecipitation of Mss51 and Pet309 with mitoribosome fractions; domain deletion analysis of Pet309; performed in S. cerevisiae","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP with ribosome, domain mutants, preprint not yet peer-reviewed","pmids":["bio_10.1101_2024.11.01.621605"],"is_preprint":true}],"current_model":"In yeast, Mss51 is a dual-function protein that activates COX1 mRNA translation (by stably associating with the mitoribosome) and post-translationally chaperones newly synthesized Cox1 within a Cox1-Cox14-Cox25-Ssc1-Mss51 assembly intermediate, coupling Cox1 synthesis to cytochrome c oxidase assembly via a homeostatic sequestration mechanism; in mammals, the ortholog MSS51/ZMYND17 localizes to skeletal muscle mitochondria where it negatively regulates mitochondrial respiration, fatty acid β-oxidation, and glycolysis downstream of TGF-β/myostatin and Site-1 protease signaling, with its expression transcriptionally controlled by Yy1, and its mRNA stability regulated by YTHDF2."},"narrative":{"teleology":[{"year":1990,"claim":"Establishing that Mss51 is a COX1-specific translational activator linked to the mitoribosome resolved its primary molecular function in yeast mitochondria.","evidence":"Genetic analysis of mss51 mutants and paromomycin-resistance suppressor mutations in 15S rRNA in S. cerevisiae","pmids":["2177521"],"confidence":"High","gaps":["No biochemical interaction with the ribosome or COX1 mRNA demonstrated","Mechanism of translational activation unknown"]},{"year":2009,"claim":"Demonstrating that Mss51 has a dual function — translational activation and post-translational chaperoning of Cox1 — and that its sequestration in Cox14-dependent assembly intermediates feeds back to limit COX1 translation established the homeostatic coupling mechanism between Cox1 synthesis and CcO assembly.","evidence":"Reciprocal co-immunoprecipitation of Mss51 with Cox1 assembly intermediates, reporter gene assays, and genetic epistasis in cox14 and other assembly mutants in S. cerevisiae","pmids":["19710419"],"confidence":"High","gaps":["Structural basis of Mss51–Cox1 interaction unknown","How Mss51 is released from assembly intermediates upon CcO maturation not defined"]},{"year":2010,"claim":"Identifying Cox25 as an essential component of the Cox1–Ssc1–Mss51–Cox14 intermediate that bridges to downstream Shy1/Cox5-containing complexes defined the compositional architecture of the early CcO assembly pathway.","evidence":"Co-immunoprecipitation, subcellular fractionation, and genetic epistasis analysis in S. cerevisiae","pmids":["21068384"],"confidence":"High","gaps":["Stoichiometry of the intermediate not determined","Mechanism of handoff from Mss51-containing to Shy1-containing complexes unclear"]},{"year":2015,"claim":"Localizing mammalian MSS51 to skeletal muscle mitochondria and showing that its disruption increases ATP production, β-oxidation, and oxidative phosphorylation revealed a functional divergence from yeast — MSS51 acts as a metabolic brake rather than a translational activator.","evidence":"Subcellular fractionation and CRISPR/Cas9 knockout in C2C12 myoblasts with Seahorse metabolic profiling","pmids":["26634192"],"confidence":"Medium","gaps":["Direct molecular target through which MSS51 constrains respiration not identified","Single cell line study"]},{"year":2018,"claim":"In vivo knockout of Zmynd17 demonstrated that MSS51 is required for normal mitochondrial morphology and that its loss causes metabolic stress, hepatic steatosis, and insulin resistance under dietary challenge, establishing systemic metabolic consequences.","evidence":"Zmynd17-KO mice with electron microscopy, oxygen consumption measurements, and high-fat diet metabolic challenge","pmids":["29913553"],"confidence":"High","gaps":["Paradox between increased respiration in myofibers and metabolic stress phenotype not fully resolved","Whether mitochondrial morphology defects are primary or secondary unclear"]},{"year":2019,"claim":"Independent Mss51-KO mice confirmed that MSS51 loss increases myofiber oxygen consumption and β-oxidation gene expression, and demonstrated protection from diet-induced obesity with improved glucose homeostasis, solidifying MSS51 as a druggable negative regulator of muscle metabolism.","evidence":"CRISPR/Cas9 Mss51-KO mice with Seahorse on isolated myofibers, hyperinsulinemic-euglycemic clamp, and metabolic phenotyping","pmids":["31527314"],"confidence":"High","gaps":["Molecular mechanism of metabolic suppression still undefined","Discrepancy with Zmynd17-KO steatosis phenotype not reconciled"]},{"year":2019,"claim":"Epistasis experiments showed that Zmynd17 and PGC1α control mitochondrial quality through independent pathways, since PGC1α overexpression worsened mitochondrial morphology in Zmynd17-KO muscle, distinguishing MSS51 from canonical biogenesis programs.","evidence":"Zmynd17-KO mice crossed with PGC1α-overexpressing mice, voluntary exercise, electron microscopy","pmids":["31921843"],"confidence":"Medium","gaps":["Pathway through which MSS51 maintains mitochondrial morphology unknown","Single morphological readout"]},{"year":2021,"claim":"Deletion of ZMYND17 in human cells did not affect mitochondrial translation but reduced cytochrome c oxidase activity and increased free F1 ATP synthase subunits, confirming mammalian MSS51 has functionally diverged from the yeast translational activator role.","evidence":"ZMYND17 gene deletion in human cells with mitochondrial translation assay, CcO activity measurement, and immunoblot","pmids":["34565318"],"confidence":"Medium","gaps":["Single lab, low citation count","Whether CcO activity reduction is direct or indirect not established","Mechanism of F1 accumulation unexplained"]},{"year":2023,"claim":"Placing MSS51 downstream of Site-1 protease in a TGF-β1 signaling axis — where S1P loss reduces Mss51 expression and MSS51 overexpression rescues the metabolic phenotype — defined the first upstream signaling pathway controlling MSS51-mediated metabolic suppression.","evidence":"Muscle-specific S1P knockout mice with Mss51 overexpression rescue, oxygen consumption rate measurements","pmids":["37002920"],"confidence":"Medium","gaps":["Intermediate signaling steps between S1P/TGF-β1 and Mss51 transcription not mapped","Single lab"]},{"year":2024,"claim":"Two independent studies defined transcriptional and post-transcriptional regulation of MSS51: Yy1 directly binds the Mss51 promoter to repress transcription, and YTHDF2 binds MSS51 mRNA to promote its degradation, linking MSS51 levels to m6A-dependent RNA decay and aging-associated superoxide control.","evidence":"ChIP, EMSA, and luciferase reporter for Yy1–Mss51 promoter binding in C2C12 and aging mouse muscle; RNA immunoprecipitation for YTHDF2–MSS51 mRNA in human granulosa cells","pmids":["39187977","38830447"],"confidence":"Medium","gaps":["Relative contributions of transcriptional vs. post-transcriptional control in physiological settings unknown","YTHDF2 regulation shown only in granulosa cells, not in muscle"]},{"year":null,"claim":"The direct molecular target or mechanism through which mammalian MSS51 constrains mitochondrial respiration remains unknown — whether it acts as a chaperone, assembly factor, or signaling scaffold has not been resolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No binding partner or substrate identified for mammalian MSS51's inhibitory function","No structural information available for MSS51 in any species","Discrepancy between two KO mouse models (obesity resistance vs. steatosis) unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0045182","term_label":"translation regulator activity","supporting_discovery_ids":[0,1]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[3,5,8]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[3,4]}],"pathway":[{"term_id":"GO:0005840","term_label":"ribosome","supporting_discovery_ids":[0,1,11]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[3,5,8]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[8,10]}],"complexes":["Cox1-Cox14-Cox25-Ssc1-Mss51 assembly intermediate (yeast)"],"partners":["COX1","COX14","COX25","SSC1","SHY1","PET309","YY1","YTHDF2"],"other_free_text":[]},"mechanistic_narrative":"MSS51 (ZMYND17) is a mitochondrial protein whose function has diverged between yeast and mammals: in yeast it couples cytochrome c oxidase (CcO) assembly to COX1 mRNA translation, while in mammals it acts as a negative regulator of mitochondrial respiration, fatty acid β-oxidation, and glycolysis in skeletal muscle. In Saccharomyces cerevisiae, Mss51 serves as a translational activator of COX1 mRNA via its 5′-UTR and is post-translationally sequestered in a Cox1–Cox14–Cox25–Ssc1–Mss51 assembly intermediate, creating a homeostatic feedback loop that limits Cox1 synthesis until CcO assembly proceeds [PMID:2177521, PMID:19710419, PMID:21068384]. In mammals, MSS51 does not regulate mitochondrial translation but instead constrains oxidative phosphorylation and cytochrome c oxidase activity; its genetic ablation in mice increases myofiber oxygen consumption, β-oxidation, and insulin sensitivity, conferring resistance to diet-induced obesity [PMID:31527314, PMID:34565318]. MSS51 expression is transcriptionally repressed by Yy1 and post-transcriptionally destabilized by YTHDF2, and it functions downstream of TGF-β1/Site-1 protease signaling to restrain muscle mitochondrial metabolism [PMID:39187977, PMID:37002920, PMID:38830447]."},"prefetch_data":{"uniprot":{"accession":"Q4VC12","full_name":"Putative protein MSS51 homolog, mitochondrial","aliases":["Zinc finger MYND domain-containing protein 17"],"length_aa":460,"mass_kda":51.3,"function":"","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q4VC12/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MSS51","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MSS51","total_profiled":1310},"omim":[{"mim_id":"621553","title":"GTP-BINDING PROTEIN 8; GTPBP8","url":"https://www.omim.org/entry/621553"},{"mim_id":"614773","title":"MSS51 MITOCHONDRIAL TRANSLATIONAL ACTIVATOR; MSS51","url":"https://www.omim.org/entry/614773"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Vesicles","reliability":"Uncertain"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"skeletal muscle","ntpm":244.5}],"url":"https://www.proteinatlas.org/search/MSS51"},"hgnc":{"alias_symbol":["FLJ39565"],"prev_symbol":["ZMYND17"]},"alphafold":{"accession":"Q4VC12","domains":[{"cath_id":"-","chopping":"43-148","consensus_level":"medium","plddt":93.5748,"start":43,"end":148}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q4VC12","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q4VC12-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q4VC12-F1-predicted_aligned_error_v6.png","plddt_mean":87.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MSS51","jax_strain_url":"https://www.jax.org/strain/search?query=MSS51"},"sequence":{"accession":"Q4VC12","fasta_url":"https://rest.uniprot.org/uniprotkb/Q4VC12.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q4VC12/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q4VC12"}},"corpus_meta":[{"pmid":"2177521","id":"PMC_2177521","title":"The MSS51 gene product is required for the translation of the COX1 mRNA in yeast mitochondria.","date":"1990","source":"Molecular & general genetics : MGG","url":"https://pubmed.ncbi.nlm.nih.gov/2177521","citation_count":84,"is_preprint":false},{"pmid":"19710419","id":"PMC_19710419","title":"Dual functions of Mss51 couple synthesis of Cox1 to assembly of cytochrome c oxidase in Saccharomyces cerevisiae mitochondria.","date":"2009","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/19710419","citation_count":79,"is_preprint":false},{"pmid":"21068384","id":"PMC_21068384","title":"Cox25 teams up with Mss51, Ssc1, and Cox14 to regulate mitochondrial cytochrome c oxidase subunit 1 expression and assembly in Saccharomyces cerevisiae.","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21068384","citation_count":68,"is_preprint":false},{"pmid":"26634192","id":"PMC_26634192","title":"Mammalian Mss51 is a skeletal muscle-specific gene modulating cellular metabolism.","date":"2015","source":"Journal of neuromuscular diseases","url":"https://pubmed.ncbi.nlm.nih.gov/26634192","citation_count":31,"is_preprint":false},{"pmid":"21531385","id":"PMC_21531385","title":"ANXA7, PPP3CB, DNAJC9, and ZMYND17 genes at chromosome 10q22 associated with the subgroup of schizophrenia with deficits in attention and executive function.","date":"2011","source":"Biological psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/21531385","citation_count":25,"is_preprint":false},{"pmid":"31527314","id":"PMC_31527314","title":"Mss51 deletion enhances muscle metabolism and glucose homeostasis in mice.","date":"2019","source":"JCI insight","url":"https://pubmed.ncbi.nlm.nih.gov/31527314","citation_count":22,"is_preprint":false},{"pmid":"29913553","id":"PMC_29913553","title":"Zmynd17 controls muscle mitochondrial quality and whole-body metabolism.","date":"2018","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/29913553","citation_count":21,"is_preprint":false},{"pmid":"39187977","id":"PMC_39187977","title":"Betaine delays age-related muscle loss by mitigating Mss51-induced impairment in mitochondrial respiration via Yin Yang1.","date":"2024","source":"Journal of cachexia, sarcopenia and muscle","url":"https://pubmed.ncbi.nlm.nih.gov/39187977","citation_count":11,"is_preprint":false},{"pmid":"31921843","id":"PMC_31921843","title":"Distinct Roles of Zmynd17 and PGC1α in Mitochondrial Quality Control and Biogenesis in Skeletal Muscle.","date":"2019","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/31921843","citation_count":10,"is_preprint":false},{"pmid":"33423297","id":"PMC_33423297","title":"Mss51 deletion increases endurance and ameliorates histopathology in the mdx mouse model of Duchenne muscular dystrophy.","date":"2021","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/33423297","citation_count":9,"is_preprint":false},{"pmid":"37338036","id":"PMC_37338036","title":"Mss51 protein inhibition serves as a novel target for type 2 diabetes: a molecular docking and simulation study.","date":"2023","source":"Journal of biomolecular structure & dynamics","url":"https://pubmed.ncbi.nlm.nih.gov/37338036","citation_count":8,"is_preprint":false},{"pmid":"37002920","id":"PMC_37002920","title":"Site-1 protease inhibits mitochondrial respiration by controlling the TGF-β target gene Mss51.","date":"2023","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/37002920","citation_count":6,"is_preprint":false},{"pmid":"38830447","id":"PMC_38830447","title":"YTHDF2 regulates MSS51 expression contributing to mitochondria dysfunction of granulosa cells in polycystic ovarian syndrome patients.","date":"2024","source":"Molecular and cellular endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/38830447","citation_count":6,"is_preprint":false},{"pmid":"34565318","id":"PMC_34565318","title":"Yeast Translational Activator Mss51p and Human ZMYND17 - Two Proteins with a Common Origin, but Different Functions.","date":"2021","source":"Biochemistry. Biokhimiia","url":"https://pubmed.ncbi.nlm.nih.gov/34565318","citation_count":4,"is_preprint":false},{"pmid":"1523888","id":"PMC_1523888","title":"Analysis of the MSS51 region on chromosome XII of Saccharomyces cerevisiae.","date":"1992","source":"Yeast (Chichester, England)","url":"https://pubmed.ncbi.nlm.nih.gov/1523888","citation_count":3,"is_preprint":false},{"pmid":"40144371","id":"PMC_40144371","title":"Association of two missense mutations in the MSS51 and KAT6B genes with body weight at different ages in cows of the Yaroslavl breed.","date":"2025","source":"Vavilovskii zhurnal genetiki i selektsii","url":"https://pubmed.ncbi.nlm.nih.gov/40144371","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.11.01.621605","title":"Insights into the Translational Activation Mechanisms of the<i>COX1</i>mRNA in Yeast Mitochondria","date":"2024-11-03","source":"bioRxiv","url":"https://doi.org/10.1101/2024.11.01.621605","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9517,"output_tokens":3101,"usd":0.037533},"stage2":{"model":"claude-opus-4-6","input_tokens":6484,"output_tokens":2741,"usd":0.151418},"total_usd":0.188951,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1990,\n      \"finding\": \"Mss51 (yeast) is specifically required for translation of the COX1 mRNA in yeast mitochondria, distinct from a splicing role; the paromomycin-resistance mutation in 15S mitoribosomal RNA interferes with Mss51 function, linking Mss51 action to the mitoribosome.\",\n      \"method\": \"Genetic analysis of mss51 mutants and paromomycin-resistance suppressor mutations in yeast mitochondria\",\n      \"journal\": \"Molecular & general genetics : MGG\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — foundational genetic loss-of-function study, 84 citations, replicated in subsequent work\",\n      \"pmids\": [\"2177521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Mss51 (yeast) has dual functions: it acts as a translational activator of COX1 mRNA via its 5'-UTR, and post-translationally it physically associates with newly synthesized, unassembled Cox1 protein in early cytochrome c oxidase assembly intermediates. Sequestration of Mss51 in these intermediates limits COX1 mRNA translation, coupling Cox1 synthesis to CcO assembly. Mss51 interaction with Cox1 requires Cox14, and Cox14-Cox1-Mss51 complex assembly depends on active Cox1 synthesis.\",\n      \"method\": \"Co-immunoprecipitation of Mss51 with Cox1 assembly intermediates, reporter gene assays, genetic analysis of cox14 and other assembly mutants in S. cerevisiae\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, reporter assays, multiple genetic epistasis tests, 79 citations\",\n      \"pmids\": [\"19710419\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Cox25, an inner mitochondrial membrane protein with a matrix-facing hydrophilic C-terminus, is an essential component of the Cox1-Ssc1-Mss51-Cox14 complex. Cox25 also interacts with Shy1 and Cox5 in a separate complex lacking Mss51, suggesting Cox25 bridges the Mss51-containing stabilization complex and downstream CcO assembly intermediates. Null mutation in Cox25 prevents Mss51 sequestration, similar to Cox14 null, and does not reduce Cox1 synthesis.\",\n      \"method\": \"Co-immunoprecipitation, subcellular fractionation, genetic epistasis analysis in S. cerevisiae\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, fractionation, multiple genetic backgrounds, 68 citations\",\n      \"pmids\": [\"21068384\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Mammalian MSS51 (ZMYND17) localizes to mitochondria in human skeletal muscle; CRISPR/Cas9-mediated disruption in C2C12 myoblasts increases cellular ATP, β-oxidation, glycolysis, and oxidative phosphorylation, indicating MSS51 negatively regulates mitochondrial metabolism.\",\n      \"method\": \"Subcellular fractionation/immunoblot for localization; CRISPR/Cas9 disruption with Seahorse metabolic assays, ATP measurement, and β-oxidation assays in C2C12 cells\",\n      \"journal\": \"Journal of neuromuscular diseases\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization by fractionation and KO with defined metabolic phenotype, single lab\",\n      \"pmids\": [\"26634192\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Zmynd17 (mouse ortholog of MSS51) is required for normal mitochondrial morphology and respiratory function in skeletal muscle; genetic inactivation causes mitochondrial structural and functional abnormalities and metabolic stress-induced hepatic steatosis and insulin resistance.\",\n      \"method\": \"Genetic knockout (Zmynd17-deficient mice), electron microscopy of mitochondrial morphology, oxygen consumption measurements, high-fat diet metabolic challenge\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined cellular and systemic phenotypes, multiple orthogonal readouts, replicated by independent lab\",\n      \"pmids\": [\"29913553\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In Mss51-KO mice, isolated myofibers show increased oxygen consumption rate; skeletal muscle exhibits upregulation of oxidative phosphorylation and fatty acid β-oxidation gene expression. Mss51-KO mice on high-fat diet are resistant to obesity with increased whole-body glucose turnover, insulin sensitivity, and β-oxidation, confirming MSS51 as a negative regulator of skeletal muscle mitochondrial respiration in vivo.\",\n      \"method\": \"CRISPR/Cas9 Mss51-KO mice, Seahorse oxygen consumption rate on isolated myofibers, hyperinsulinemic-euglycemic clamp, metabolic phenotyping\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo KO with multiple orthogonal metabolic readouts, independent replication of in vitro findings\",\n      \"pmids\": [\"31527314\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Zmynd17-mediated mitochondrial quality control in skeletal muscle is mechanistically distinct from PGC1α-induced mitochondrial biogenesis; PGC1α overexpression in Zmynd17-KO muscle exacerbates mitochondrial morphological abnormalities, and voluntary exercise improves mitochondrial morphology independently of Zmynd17 activity.\",\n      \"method\": \"Genetic epistasis: Zmynd17-KO mice with PGC1α overexpression, voluntary exercise protocol, electron microscopy of mitochondrial morphology\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — epistasis with defined morphological readout, single lab\",\n      \"pmids\": [\"31921843\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Human ZMYND17 deletion does not affect mitochondrial translation but reduces cytochrome c oxidase activity and increases free F1 subunit of ATP synthase, demonstrating functional divergence from yeast Mss51p translational activator role.\",\n      \"method\": \"ZMYND17 gene deletion in human cells, mitochondrial translation assay, cytochrome c oxidase activity measurement, immunoblot for ATP synthase F1 subunit\",\n      \"journal\": \"Biochemistry. Biokhimiia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO with defined biochemical readouts, single lab, low citation count\",\n      \"pmids\": [\"34565318\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Site-1 protease (S1P) acts upstream of Mss51 to inhibit skeletal muscle mitochondrial respiration; S1P disruption in mouse skeletal muscle reduces Mss51 expression and increases mitochondrial respiration. Mss51 overexpression counteracts the increased respiration caused by S1P deficiency, placing Mss51 downstream of S1P in a TGF-β1 signaling pathway regulating muscle metabolism.\",\n      \"method\": \"Muscle-specific S1P knockout mice, Mss51 overexpression rescue experiment, oxygen consumption rate measurement, gene expression analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with rescue, defined metabolic phenotype, single lab\",\n      \"pmids\": [\"37002920\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"YTHDF2 binds MSS51 mRNA (demonstrated by RNA immunoprecipitation) and reduces MSS51 expression; reduced MSS51 leads to mitochondrial damage, reduced ATP, increased ROS, and reduced expression of glycolysis genes (LDHA, PFKP, PKM) in granulosa cells.\",\n      \"method\": \"RNA immunoprecipitation (RIP) assay for YTHDF2-MSS51 mRNA binding, YTHDF2 overexpression and MSS51 knockdown with mitochondrial morphology imaging, ATP and ROS measurement, qPCR for glycolytic genes in human granulosa cells\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — RIP confirms direct RNA binding, functional readouts, single lab\",\n      \"pmids\": [\"38830447\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Betaine transcriptionally suppresses Mss51 via Yin Yang 1 (Yy1): Yy1 binds the Mss51 promoter (shown by ChIP and EMSA), suppressing Mss51 transcription; this restores Mss51-mediated suppression of mitochondrial respiration proteins and reduces superoxide in C2C12 cells and aging mouse muscle.\",\n      \"method\": \"Luciferase reporter assay, chromatin immunoprecipitation (ChIP), electrophoretic mobility shift assay (EMSA), AAV-mediated in vivo overexpression, Seahorse assay, immunofluorescence\",\n      \"journal\": \"Journal of cachexia, sarcopenia and muscle\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods (ChIP, EMSA, reporter, in vivo rescue), single lab\",\n      \"pmids\": [\"39187977\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Yeast Mss51 and Pet309 both physically interact with the mitoribosome independently of COX1 mRNA and of each other; Pet309's association with the ribosome and with COX1 mRNA depends on its N-terminal domain. These stable mitoribosome interactions suggest that translational activators function by positioning the ribosome at the mRNA rather than solely through 5'-UTR binding.\",\n      \"method\": \"Co-immunoprecipitation of Mss51 and Pet309 with mitoribosome fractions; domain deletion analysis of Pet309; performed in S. cerevisiae\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP with ribosome, domain mutants, preprint not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2024.11.01.621605\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"In yeast, Mss51 is a dual-function protein that activates COX1 mRNA translation (by stably associating with the mitoribosome) and post-translationally chaperones newly synthesized Cox1 within a Cox1-Cox14-Cox25-Ssc1-Mss51 assembly intermediate, coupling Cox1 synthesis to cytochrome c oxidase assembly via a homeostatic sequestration mechanism; in mammals, the ortholog MSS51/ZMYND17 localizes to skeletal muscle mitochondria where it negatively regulates mitochondrial respiration, fatty acid β-oxidation, and glycolysis downstream of TGF-β/myostatin and Site-1 protease signaling, with its expression transcriptionally controlled by Yy1, and its mRNA stability regulated by YTHDF2.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MSS51 (ZMYND17) is a mitochondrial protein whose function has diverged between yeast and mammals: in yeast it couples cytochrome c oxidase (CcO) assembly to COX1 mRNA translation, while in mammals it acts as a negative regulator of mitochondrial respiration, fatty acid β-oxidation, and glycolysis in skeletal muscle. In Saccharomyces cerevisiae, Mss51 serves as a translational activator of COX1 mRNA via its 5′-UTR and is post-translationally sequestered in a Cox1–Cox14–Cox25–Ssc1–Mss51 assembly intermediate, creating a homeostatic feedback loop that limits Cox1 synthesis until CcO assembly proceeds [PMID:2177521, PMID:19710419, PMID:21068384]. In mammals, MSS51 does not regulate mitochondrial translation but instead constrains oxidative phosphorylation and cytochrome c oxidase activity; its genetic ablation in mice increases myofiber oxygen consumption, β-oxidation, and insulin sensitivity, conferring resistance to diet-induced obesity [PMID:31527314, PMID:34565318]. MSS51 expression is transcriptionally repressed by Yy1 and post-transcriptionally destabilized by YTHDF2, and it functions downstream of TGF-β1/Site-1 protease signaling to restrain muscle mitochondrial metabolism [PMID:39187977, PMID:37002920, PMID:38830447].\",\n  \"teleology\": [\n    {\n      \"year\": 1990,\n      \"claim\": \"Establishing that Mss51 is a COX1-specific translational activator linked to the mitoribosome resolved its primary molecular function in yeast mitochondria.\",\n      \"evidence\": \"Genetic analysis of mss51 mutants and paromomycin-resistance suppressor mutations in 15S rRNA in S. cerevisiae\",\n      \"pmids\": [\"2177521\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No biochemical interaction with the ribosome or COX1 mRNA demonstrated\", \"Mechanism of translational activation unknown\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Demonstrating that Mss51 has a dual function — translational activation and post-translational chaperoning of Cox1 — and that its sequestration in Cox14-dependent assembly intermediates feeds back to limit COX1 translation established the homeostatic coupling mechanism between Cox1 synthesis and CcO assembly.\",\n      \"evidence\": \"Reciprocal co-immunoprecipitation of Mss51 with Cox1 assembly intermediates, reporter gene assays, and genetic epistasis in cox14 and other assembly mutants in S. cerevisiae\",\n      \"pmids\": [\"19710419\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of Mss51–Cox1 interaction unknown\", \"How Mss51 is released from assembly intermediates upon CcO maturation not defined\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identifying Cox25 as an essential component of the Cox1–Ssc1–Mss51–Cox14 intermediate that bridges to downstream Shy1/Cox5-containing complexes defined the compositional architecture of the early CcO assembly pathway.\",\n      \"evidence\": \"Co-immunoprecipitation, subcellular fractionation, and genetic epistasis analysis in S. cerevisiae\",\n      \"pmids\": [\"21068384\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry of the intermediate not determined\", \"Mechanism of handoff from Mss51-containing to Shy1-containing complexes unclear\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Localizing mammalian MSS51 to skeletal muscle mitochondria and showing that its disruption increases ATP production, β-oxidation, and oxidative phosphorylation revealed a functional divergence from yeast — MSS51 acts as a metabolic brake rather than a translational activator.\",\n      \"evidence\": \"Subcellular fractionation and CRISPR/Cas9 knockout in C2C12 myoblasts with Seahorse metabolic profiling\",\n      \"pmids\": [\"26634192\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular target through which MSS51 constrains respiration not identified\", \"Single cell line study\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"In vivo knockout of Zmynd17 demonstrated that MSS51 is required for normal mitochondrial morphology and that its loss causes metabolic stress, hepatic steatosis, and insulin resistance under dietary challenge, establishing systemic metabolic consequences.\",\n      \"evidence\": \"Zmynd17-KO mice with electron microscopy, oxygen consumption measurements, and high-fat diet metabolic challenge\",\n      \"pmids\": [\"29913553\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Paradox between increased respiration in myofibers and metabolic stress phenotype not fully resolved\", \"Whether mitochondrial morphology defects are primary or secondary unclear\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Independent Mss51-KO mice confirmed that MSS51 loss increases myofiber oxygen consumption and β-oxidation gene expression, and demonstrated protection from diet-induced obesity with improved glucose homeostasis, solidifying MSS51 as a druggable negative regulator of muscle metabolism.\",\n      \"evidence\": \"CRISPR/Cas9 Mss51-KO mice with Seahorse on isolated myofibers, hyperinsulinemic-euglycemic clamp, and metabolic phenotyping\",\n      \"pmids\": [\"31527314\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism of metabolic suppression still undefined\", \"Discrepancy with Zmynd17-KO steatosis phenotype not reconciled\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Epistasis experiments showed that Zmynd17 and PGC1α control mitochondrial quality through independent pathways, since PGC1α overexpression worsened mitochondrial morphology in Zmynd17-KO muscle, distinguishing MSS51 from canonical biogenesis programs.\",\n      \"evidence\": \"Zmynd17-KO mice crossed with PGC1α-overexpressing mice, voluntary exercise, electron microscopy\",\n      \"pmids\": [\"31921843\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Pathway through which MSS51 maintains mitochondrial morphology unknown\", \"Single morphological readout\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Deletion of ZMYND17 in human cells did not affect mitochondrial translation but reduced cytochrome c oxidase activity and increased free F1 ATP synthase subunits, confirming mammalian MSS51 has functionally diverged from the yeast translational activator role.\",\n      \"evidence\": \"ZMYND17 gene deletion in human cells with mitochondrial translation assay, CcO activity measurement, and immunoblot\",\n      \"pmids\": [\"34565318\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, low citation count\", \"Whether CcO activity reduction is direct or indirect not established\", \"Mechanism of F1 accumulation unexplained\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Placing MSS51 downstream of Site-1 protease in a TGF-β1 signaling axis — where S1P loss reduces Mss51 expression and MSS51 overexpression rescues the metabolic phenotype — defined the first upstream signaling pathway controlling MSS51-mediated metabolic suppression.\",\n      \"evidence\": \"Muscle-specific S1P knockout mice with Mss51 overexpression rescue, oxygen consumption rate measurements\",\n      \"pmids\": [\"37002920\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Intermediate signaling steps between S1P/TGF-β1 and Mss51 transcription not mapped\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Two independent studies defined transcriptional and post-transcriptional regulation of MSS51: Yy1 directly binds the Mss51 promoter to repress transcription, and YTHDF2 binds MSS51 mRNA to promote its degradation, linking MSS51 levels to m6A-dependent RNA decay and aging-associated superoxide control.\",\n      \"evidence\": \"ChIP, EMSA, and luciferase reporter for Yy1–Mss51 promoter binding in C2C12 and aging mouse muscle; RNA immunoprecipitation for YTHDF2–MSS51 mRNA in human granulosa cells\",\n      \"pmids\": [\"39187977\", \"38830447\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relative contributions of transcriptional vs. post-transcriptional control in physiological settings unknown\", \"YTHDF2 regulation shown only in granulosa cells, not in muscle\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The direct molecular target or mechanism through which mammalian MSS51 constrains mitochondrial respiration remains unknown — whether it acts as a chaperone, assembly factor, or signaling scaffold has not been resolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No binding partner or substrate identified for mammalian MSS51's inhibitory function\", \"No structural information available for MSS51 in any species\", \"Discrepancy between two KO mouse models (obesity resistance vs. steatosis) unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0045182\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [3, 5, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [3, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0005840\", \"supporting_discovery_ids\": [0, 1, 11]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [3, 5, 8]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [8, 10]}\n    ],\n    \"complexes\": [\n      \"Cox1-Cox14-Cox25-Ssc1-Mss51 assembly intermediate (yeast)\"\n    ],\n    \"partners\": [\n      \"COX1\",\n      \"COX14\",\n      \"COX25\",\n      \"SSC1\",\n      \"SHY1\",\n      \"PET309\",\n      \"YY1\",\n      \"YTHDF2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}