{"gene":"MIEF1","run_date":"2026-04-28T18:30:28","timeline":{"discoveries":[{"year":2011,"finding":"MIEF1 (MiD51) is anchored to the outer mitochondrial membrane and directly recruits Drp1 to mitochondria independently of hFis1, Mff, and Mfn2; elevated MIEF1 inhibits Drp1 activity and promotes mitochondrial fusion, while MIEF1 depletion causes fragmentation. MIEF1 also interacts with hFis1, and elevated hFis1 partially reverses MIEF1-induced fusion.","method":"Overexpression/knockdown with confocal imaging of mitochondrial morphology, co-immunoprecipitation, subcellular fractionation","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (Co-IP, KD/OE with defined morphological phenotype, fractionation), foundational paper replicated by subsequent studies","pmids":["21701560"],"is_preprint":false},{"year":2011,"finding":"MiD49 and MiD51 form foci and rings around mitochondria, directly recruit Drp1 to the mitochondrial surface, and their knockdown reduces Drp1 association leading to unopposed fusion; overexpression sequesters Drp1 and causes fused tubules to associate with actin.","method":"Co-immunoprecipitation, siRNA knockdown, overexpression with fluorescence microscopy","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP and KD with defined phenotype, replicated across multiple labs","pmids":["21508961"],"is_preprint":false},{"year":2013,"finding":"MiD49 and MiD51 can mediate Drp1 recruitment and mitochondrial fission independently of Fis1 and Mff, as shown in Fis1/Mff double-null cells; Fis1 and Mff regulate the number and size of Drp1 puncta on mitochondria.","method":"Genetic knockout (Fis1-null, Mff-null, Fis1/Mff-null cells), immunofluorescence of Drp1 puncta","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 — clean genetic KO with specific phenotypic readout, highly cited and replicated","pmids":["23283981"],"is_preprint":false},{"year":2013,"finding":"MiD49/51 overexpression blocks fission by sequestering Drp1 specifically at mitochondria in a dominant-negative manner, causing unopposed fusion requiring mitofusins 1 and 2. MiD49/51 are not targeted to peroxisomes; when artificially targeted to peroxisomes or lysosomes, they specifically recruit Drp1 to those organelles.","method":"Overexpression at varying levels, mitofusin 1/2 KO epistasis, organelle retargeting constructs, fluorescence microscopy","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — epistasis experiments and organelle retargeting provide strong mechanistic evidence","pmids":["23921378"],"is_preprint":false},{"year":2014,"finding":"Crystal structure of the cytosolic domain of human MiD51 reveals a nucleotidyltransferase fold that lacks catalytic residues but specifically binds GDP and ADP. A region outside the nucleotidyltransferase fold is required for Drp1 recruitment and assembly of MiD51 into foci. MiD51 foci depend on Drp1 presence and are distributed to daughter organelles after fission.","method":"X-ray crystallography, nucleotide-binding assays, mutagenesis, live-cell imaging","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 — crystal structure with mutagenesis and functional validation in cells","pmids":["24515348"],"is_preprint":false},{"year":2014,"finding":"MiD51 contains a nucleotidyltransferase domain that binds ADP with high affinity. MiD51 recruits Drp1 via a surface loop independently of ADP binding, but without nucleotide binding the recruited Drp1 cannot be activated for fission. Purified MiD51 strongly inhibits Drp1 assembly and GTP hydrolysis in the absence of ADP; ADP addition relieves this inhibition and promotes Drp1 assembly into spirals with enhanced GTP hydrolysis.","method":"X-ray crystallography, in vitro GTPase assay, Drp1 assembly assay with purified proteins, mutagenesis","journal":"Structure","confidence":"High","confidence_rationale":"Tier 1 — reconstitution in vitro with purified proteins, structure, and mutagenesis; replicated by Richter et al. 2014","pmids":["24508339"],"is_preprint":false},{"year":2016,"finding":"MiD51 can suppress Mff-dependent enhancement of Drp1 GTPase activity. Proximity-based biotin labeling (BioID) shows close associations between MiD51, Mff, and Drp1, but not Fis1. Loss of MiD49 and MiD51 confers increased resistance to intrinsic apoptotic stimuli.","method":"BioID proximity labeling, CRISPR/Cas9 gene editing, in vitro Drp1 GTPase assay, apoptosis assays","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro GTPase assay combined with proximity labeling and clean KO cells","pmids":["27076521"],"is_preprint":false},{"year":2015,"finding":"During UV-induced apoptosis, the interaction between Drp1 and MiD51/MIEF1 decreases significantly, while interaction between Fis1 and MiD51/MIEF1 increases markedly, suggesting Fis1 competitively binds MiD51/MIEF1 to activate Drp1 indirectly. Phosphorylation of Drp1-Ser637 is essential for its interaction with Mff.","method":"Co-immunoprecipitation before and after UV irradiation, phospho-specific antibodies, western blotting","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 3 — single Co-IP under apoptotic conditions; mechanistic model supported but not fully reconstituted","pmids":["26432782"],"is_preprint":false},{"year":2018,"finding":"MIEF1-MP (MIEF1 microprotein), encoded by a small ORF in the 5'UTR of MIEF1 mRNA, localizes to the mitochondrial matrix and interacts with the mitochondrial ribosome (mitoribosome). Loss of MIEF1-MP decreases mitochondrial translation rate; elevated MIEF1-MP increases translation rate.","method":"APEX2 proximity labeling, siRNA knockdown, overexpression, mitochondrial translation assay, subcellular fractionation","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 2 — proximity labeling with functional validation (translation rate assay with KD and OE), multiple orthogonal methods","pmids":["30215512"],"is_preprint":false},{"year":2018,"finding":"The predominant translational product of the MIEF1 gene in human cells and colon tissue is not the canonical 463 aa MiD51 protein but the small 70 aa alternative ORF protein (altMiD51), as determined by absolute quantification with stable isotope-labeled peptides.","method":"Stable isotope-labeled peptide absolute quantification, parallel reaction monitoring mass spectrometry","journal":"Molecular & cellular proteomics","confidence":"High","confidence_rationale":"Tier 1 — quantitative mass spectrometry with internal standards; direct measurement","pmids":["30181344"],"is_preprint":false},{"year":2019,"finding":"MIEF1 loss triggers imbalance of BCL2 family members on mitochondria, leading to BAX translocation to mitochondria, decreased mitochondrial membrane potential, and release of DIABLO/SMAC and cytochrome c. MIEF1 deficiency also impairs mitochondrial respiration, induces oxidative stress, and sensitizes cells to PINK1-PRKN-mediated mitophagy. Staurosporine-induced MIEF1 degradation occurs via the ubiquitin-proteasome system.","method":"CRISPR KO, siRNA knockdown, flow cytometry, western blotting, mitochondrial respiration assay, immunofluorescence","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO with multiple defined cellular phenotypes, but single laboratory","pmids":["30894073"],"is_preprint":false},{"year":2019,"finding":"The interaction between Drp1 and MiD51 is regulated by GTP binding and depends on Drp1 polymerization. Two regions on MiD51 directly bind Drp1, and dimerization of MiD51 (dependent on residue C452) is required for mitochondrial dynamics regulation.","method":"Co-immunoprecipitation, mutagenesis (C452), GTP-binding assays, fluorescence microscopy","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2–3 — mutagenesis with Co-IP and functional readout, single laboratory","pmids":["30703167"],"is_preprint":false},{"year":2021,"finding":"In intact mammalian cells, Drp1 exists as a mixture of oligomeric assemblies. Mff preferentially binds higher-order Drp1 oligomers, while MIEFs (MIEF1 and MIEF2) bind a wider range including lower oligomeric states and recruit both active and inactive Drp1 mutants. Forced recruitment of Drp1 to mitochondria by MIEFs facilitates Drp1 oligomerization. MIEFs serve as a platform facilitating Drp1 binding to Mff; loss of MIEFs severely impairs the Drp1-Mff interaction.","method":"In vivo chemical crosslinking, co-immunoprecipitation, Drp1 oligomerization mutants, fluorescence microscopy in Mff/MIEF1/2-deficient cells","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo crosslinking with multiple Drp1 mutants and KO cell lines, single laboratory","pmids":["34805137"],"is_preprint":false},{"year":2024,"finding":"Long-chain acyl-CoA (LCACA) activates MiD51 by inducing its oligomerization via binding in the nucleotide-binding pocket (confirmed by a point mutation reducing binding and oligomerization). LCACA-induced MiD51 oligomers stimulate DRP1 GTPase activity; a LCACA-binding mutant fails to assemble into mitochondrial puncta or rescue MiD49/51 KD effects. MiD51 oligomers synergize with Mff but not actin filaments in DRP1 activation. Cellular oleic acid treatment promotes mitochondrial fission in an MiD49/51-dependent manner.","method":"In vitro GTPase assay, oligomerization assay, point mutagenesis, siRNA knockdown rescue, confocal microscopy, lipid-binding biochemistry","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with mutagenesis and cellular validation; identifies endogenous ligand","pmids":["38594588"],"is_preprint":false},{"year":2024,"finding":"Extracellular matrix stiffness, spatial confinement, and mechanical forces (including mouse skin stretching) regulate mitochondrial dynamics through MIEF1 phosphorylation. Actomyosin tension promotes MIEF1 phosphorylation, limiting DRP1 recruitment to mitochondria and reducing peri-mitochondrial F-actin formation and fission. DRP1- and MIEF1/2-dependent fission is required and sufficient to regulate YAP/TAZ, SREBP1/2, and NRF2 transcription factors, controlling cell proliferation, lipogenesis, antioxidant metabolism, and adipocyte differentiation in response to mechanical cues.","method":"Phosphorylation assays, DRP1/MIEF1/2 KO/KD with defined transcriptional and metabolic readouts, in vivo mouse skin stretching, live imaging, genetic epistasis","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods, in vivo validation, epistasis with transcriptional readouts; replicated across multiple mechanical stimuli","pmids":["39433949"],"is_preprint":false},{"year":2021,"finding":"Dominant heterozygous MIEF1 variants causing late-onset optic neuropathy do not disrupt MiD51 localization to the outer mitochondrial membrane or its oligomerization, but significantly disrupt mitochondrial network dynamics as shown by high-resolution live confocal imaging.","method":"Targeted sequencing, live confocal microscopy of mitochondrial dynamics, oligomerization assays in patient-derived variant cells","journal":"Molecular neurodegeneration","confidence":"Medium","confidence_rationale":"Tier 2 — functional validation of disease variants with live imaging, single study","pmids":["33632269"],"is_preprint":false},{"year":2026,"finding":"MAOA (monoamine oxidase A) physically interacts with MIEF1 and enhances MIEF1-DRP1 coupling; cortisol increases both MIEF1 and DRP1-Ser616 phosphorylation, driving excessive mitochondrial fission and trabecular meshwork fibrosis. Knockdown of MAOA or MIEF1 reduces oxidative stress, mitochondrial fragmentation, and extracellular matrix remodeling.","method":"Co-immunoprecipitation, molecular docking, molecular dynamics simulations, siRNA knockdown, western blotting, confocal microscopy","journal":"Free radical biology & medicine","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP with computational support and functional KD readout, single study","pmids":["41579974"],"is_preprint":false}],"current_model":"MIEF1 (MiD51) is an outer mitochondrial membrane protein that recruits cytosolic DRP1 to mitochondria via a dedicated surface loop, then modulates DRP1 activity: in the absence of metabolic cofactors (ADP or long-chain acyl-CoA), MIEF1 sequesters and inhibits DRP1; binding of ADP or LCACA to MIEF1's nucleotidyltransferase-fold domain induces MIEF1 oligomerization and relieves inhibition to promote DRP1 assembly and GTPase-driven fission. Actomyosin-mediated phosphorylation of MIEF1 limits DRP1 recruitment during mechanotransduction, making MIEF1-dependent fission a signaling node that controls YAP/TAZ, SREBP, and NRF2 transcription. Additionally, the MIEF1 locus encodes a microprotein (MIEF1-MP) that localizes to the mitochondrial matrix and stimulates mitoribosome-dependent translation."},"narrative":{"teleology":[{"year":2011,"claim":"Before MIEF1 was identified, DRP1 recruitment to mitochondria was attributed to Fis1 and Mff; the discovery that MIEF1 directly recruits DRP1 independently of these receptors established an alternative, parallel recruitment pathway and revealed that overexpression paradoxically inhibits fission.","evidence":"Overexpression/knockdown with Co-IP, subcellular fractionation, and confocal imaging in mammalian cells (two independent labs)","pmids":["21701560","21508961"],"confidence":"High","gaps":["Structural basis of MIEF1–DRP1 interaction unknown","Whether MIEF1 alone is sufficient for fission in vivo unresolved","Relationship between MiD49 and MiD51 redundancy not defined"]},{"year":2013,"claim":"The question of whether MIEF1/MiD51 and MiD49 can execute DRP1-dependent fission without Fis1 and Mff was answered: genetic elimination of Fis1 and Mff demonstrated that MiD proteins constitute a functionally independent receptor pathway.","evidence":"Fis1/Mff double-knockout cells with immunofluorescence of DRP1 puncta; organelle retargeting of MiD to peroxisomes/lysosomes","pmids":["23283981","23921378"],"confidence":"High","gaps":["Direct biochemical mechanism by which MIEF1 modulates DRP1 activity unknown","Role of nucleotide binding unexplored"]},{"year":2014,"claim":"Crystallography resolved a central paradox—how MIEF1 both recruits and inhibits DRP1—by showing that its nucleotidyltransferase-fold domain binds ADP, and that a separate surface loop recruits DRP1; without ADP, MIEF1 inhibits DRP1 assembly and GTPase activity, while ADP binding relieves inhibition and promotes fission-competent DRP1 spirals.","evidence":"X-ray crystallography, nucleotide-binding assays, in vitro reconstitution with purified proteins, mutagenesis","pmids":["24515348","24508339"],"confidence":"High","gaps":["Identity of the physiological metabolite controlling MIEF1 in cells not established","Oligomerization state of MIEF1 and its regulation not defined"]},{"year":2016,"claim":"Functional interplay between MIEF1 and Mff was clarified: MIEF1 suppresses Mff-dependent enhancement of DRP1 GTPase activity, and proximity labeling confirmed close association of MIEF1, Mff, and DRP1 in intact cells; loss of MiD49/51 increased resistance to intrinsic apoptosis.","evidence":"BioID proximity labeling, CRISPR knockout, in vitro DRP1 GTPase assay, apoptosis assays","pmids":["27076521"],"confidence":"High","gaps":["How MIEF1 physically integrates with Mff on the same DRP1 oligomer unclear","Apoptotic role not distinguished from general fission defect"]},{"year":2018,"claim":"A previously unrecognized translational product of the MIEF1 locus—the 70-amino-acid microprotein MIEF1-MP (altMiD51)—was discovered to localize to the mitochondrial matrix, interact with the mitoribosome, and regulate mitochondrial translation, representing a dual-function locus.","evidence":"APEX2 proximity labeling, stable isotope-labeled peptide absolute quantification, knockdown and overexpression with mitochondrial translation assays","pmids":["30215512","30181344"],"confidence":"High","gaps":["Specific mitoribosome subunit contact site not identified","Whether MIEF1-MP affects specific mitochondrial-encoded transcripts unknown","Functional coupling between MiD51 and MIEF1-MP products unexamined"]},{"year":2019,"claim":"MIEF1 loss was shown to perturb mitochondrial homeostasis beyond fission—imbalancing BCL2 family members, causing BAX translocation, cytochrome c release, impaired respiration, and sensitization to PINK1-PRKN mitophagy—linking MIEF1 to mitochondrial quality control.","evidence":"CRISPR knockout, flow cytometry, mitochondrial respiration assay, western blotting, immunofluorescence","pmids":["30894073"],"confidence":"Medium","gaps":["Whether apoptotic sensitization is a direct effect or secondary to chronic fission imbalance is unclear","Single laboratory; independent replication needed"]},{"year":2021,"claim":"In vivo crosslinking revealed that MIEFs bind a broader range of DRP1 oligomeric states than Mff and serve as platforms facilitating DRP1 oligomerization and subsequent handoff to Mff, resolving how these receptors cooperate hierarchically.","evidence":"In vivo chemical crosslinking, Co-IP with DRP1 oligomerization mutants, Mff/MIEF1/2-deficient cell lines","pmids":["34805137"],"confidence":"Medium","gaps":["Structural model of the MIEF1-DRP1-Mff ternary complex lacking","Stoichiometry of the handoff not determined"]},{"year":2021,"claim":"Dominant heterozygous MIEF1 variants were linked to late-onset optic neuropathy, establishing the first Mendelian disease association and demonstrating that variants disrupting mitochondrial network dynamics without affecting membrane targeting or oligomerization can cause neurodegeneration.","evidence":"Targeted sequencing in optic neuropathy patients, live confocal imaging of mitochondrial dynamics, oligomerization assays of variant proteins","pmids":["33632269"],"confidence":"Medium","gaps":["Precise biochemical defect of disease variants (e.g. DRP1 binding affinity) not measured","Penetrance and genotype-phenotype correlation require larger cohorts"]},{"year":2024,"claim":"Long-chain acyl-CoA was identified as a second endogenous activating ligand of MIEF1, binding the same nucleotide pocket to induce oligomerization and stimulate DRP1 GTPase activity, linking fatty acid metabolism to mitochondrial fission through MiD51.","evidence":"In vitro GTPase and oligomerization assays with purified proteins, point mutagenesis of LCACA-binding site, siRNA rescue, oleic acid cellular treatment","pmids":["38594588"],"confidence":"High","gaps":["Relative contribution of ADP vs. LCACA under physiological conditions unknown","Whether other acyl-CoA chain lengths have distinct effects untested"]},{"year":2024,"claim":"MIEF1 was established as a mechanotransduction effector: actomyosin tension phosphorylates MIEF1, limiting DRP1 recruitment and fission, and this pathway is necessary and sufficient to regulate YAP/TAZ, SREBP, and NRF2 transcription in response to matrix stiffness.","evidence":"Phosphorylation assays, DRP1/MIEF1/2 KO/KD with transcriptional and metabolic readouts, in vivo mouse skin stretching, genetic epistasis","pmids":["39433949"],"confidence":"High","gaps":["Kinase directly phosphorylating MIEF1 not identified","Specific phosphorylation sites and their individual contributions not mapped","How mitochondrial fission state is decoded by transcription factors mechanistically unresolved"]},{"year":null,"claim":"Key unresolved questions include: the identity of the kinase that phosphorylates MIEF1 downstream of actomyosin tension; a structural model of the MIEF1-DRP1-Mff ternary complex; the physiological balance between ADP and LCACA in regulating MIEF1 oligomerization; and whether MIEF1-MP functionally coordinates with MiD51 to integrate mitochondrial translation and dynamics.","evidence":"","pmids":[],"confidence":"Low","gaps":["No kinase identified for mechanotransduction-dependent MIEF1 phosphorylation","No ternary structural model of MIEF1-DRP1-Mff","Functional interplay between MiD51 and MIEF1-MP gene products untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,5,6,12,13]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,2,12]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0,1,4,8,15]}],"pathway":[{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[0,1,2,5,13,14]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[6,7,10]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[13,14]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[14]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[8,9]}],"complexes":[],"partners":["DNM1L","MFF","FIS1","MIEF2","MAOA"],"other_free_text":[]},"mechanistic_narrative":"MIEF1 (MiD51) is an outer mitochondrial membrane receptor that governs mitochondrial fission by recruiting and regulating the dynamin-related GTPase DRP1, acting as a metabolic and mechanical signaling node. Its cytosolic nucleotidyltransferase-fold domain binds ADP and long-chain acyl-CoA (LCACA); in the ligand-free state MIEF1 sequesters DRP1 and inhibits its GTPase activity, whereas ADP or LCACA binding induces MIEF1 oligomerization that relieves inhibition, promotes DRP1 assembly into fission-competent spirals, and synergizes with Mff [PMID:24508339, PMID:38594588, PMID:34805137]. Actomyosin-dependent phosphorylation of MIEF1 limits DRP1 recruitment in response to extracellular matrix stiffness and mechanical forces, coupling mitochondrial fission to YAP/TAZ, SREBP, and NRF2 transcriptional programs that control proliferation, lipogenesis, and antioxidant metabolism [PMID:39433949]. The MIEF1 locus additionally encodes a small open reading frame (MIEF1-MP/altMiD51) whose 70-amino-acid microprotein localizes to the mitochondrial matrix, interacts with the mitoribosome, and stimulates mitochondrial translation [PMID:30215512, PMID:30181344]. Dominant heterozygous MIEF1 variants cause late-onset optic neuropathy by disrupting mitochondrial network dynamics without abolishing membrane targeting [PMID:33632269]."},"prefetch_data":{"uniprot":{"accession":"L0R8F8","full_name":"Mitochondrial ribosome and complex I assembly factor AltMIEF1","aliases":["Alternative MIEF1 protein","AltMIEF1","MIEF1 microprotein","MIEF1-MP","alternative transcript upstream of MiD51","AltMiD51"],"length_aa":70,"mass_kda":8.4,"function":"Assembly factor involved in the biogenesis of the mitochondrial-specific ribosomes (mitoribosomes) (PubMed:28892042, PubMed:30215512, PubMed:31666358). Specifically associates with intermediates of the mitochondrial ribosome large subunit (mt-LSU) and is required for proper ribosome assembly, possibly preventing premature association of the large and small ribosomal subunits (PubMed:28892042, PubMed:30215512, PubMed:31666358). Thereby, indirectly regulates mitochondrial translation (PubMed:28892042, PubMed:30215512, PubMed:31666358). It is also required for complete assembly of the mitochondrial respiratory chain complex I (PubMed:31666358). May also function in DNM1L-mediated mitochondrial fission (PubMed:29083303)","subcellular_location":"Mitochondrion matrix","url":"https://www.uniprot.org/uniprotkb/L0R8F8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MIEF1","classification":"Not Classified","n_dependent_lines":22,"n_total_lines":1208,"dependency_fraction":0.018211920529801324},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MIEF1","total_profiled":1310},"omim":[{"mim_id":"620550","title":"OPTIC ATROPHY 14; OPA14","url":"https://www.omim.org/entry/620550"},{"mim_id":"615498","title":"MITOCHONDRIAL ELONGATION FACTOR 2; MIEF2","url":"https://www.omim.org/entry/615498"},{"mim_id":"615497","title":"MITOCHONDRIAL ELONGATION FACTOR 1; MIEF1","url":"https://www.omim.org/entry/615497"},{"mim_id":"165500","title":"OPTIC ATROPHY 1; OPA1","url":"https://www.omim.org/entry/165500"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Intermediate filaments","reliability":"Uncertain"},{"location":"Mitochondria","reliability":"Uncertain"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MIEF1"},"hgnc":{"alias_symbol":["FLJ20232","MiD51","L0R8F8","D3A"],"prev_symbol":["SMCR7L"]},"alphafold":{"accession":"L0R8F8","domains":[{"cath_id":"-","chopping":"2-7_26-60","consensus_level":"medium","plddt":88.1088,"start":2,"end":60}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/L0R8F8","model_url":"https://alphafold.ebi.ac.uk/files/AF-L0R8F8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-L0R8F8-F1-predicted_aligned_error_v6.png","plddt_mean":86.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MIEF1","jax_strain_url":"https://www.jax.org/strain/search?query=MIEF1"},"sequence":{"accession":"L0R8F8","fasta_url":"https://rest.uniprot.org/uniprotkb/L0R8F8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/L0R8F8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/L0R8F8"}},"corpus_meta":[{"pmid":"23283981","id":"PMC_23283981","title":"Fis1, Mff, MiD49, and MiD51 mediate Drp1 recruitment in mitochondrial fission.","date":"2013","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/23283981","citation_count":993,"is_preprint":false},{"pmid":"21508961","id":"PMC_21508961","title":"MiD49 and MiD51, new components of the mitochondrial fission machinery.","date":"2011","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/21508961","citation_count":514,"is_preprint":false},{"pmid":"21701560","id":"PMC_21701560","title":"Human MIEF1 recruits Drp1 to mitochondrial outer membranes and promotes mitochondrial fusion rather than fission.","date":"2011","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/21701560","citation_count":296,"is_preprint":false},{"pmid":"27076521","id":"PMC_27076521","title":"Cooperative and independent roles of the Drp1 adaptors Mff, MiD49 and MiD51 in mitochondrial fission.","date":"2016","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/27076521","citation_count":263,"is_preprint":false},{"pmid":"23921378","id":"PMC_23921378","title":"Adaptor proteins MiD49 and MiD51 can act independently of Mff and Fis1 in Drp1 recruitment and are specific for mitochondrial fission.","date":"2013","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23921378","citation_count":247,"is_preprint":false},{"pmid":"29431643","id":"PMC_29431643","title":"Epigenetic Dysregulation of the Dynamin-Related Protein 1 Binding Partners MiD49 and MiD51 Increases Mitotic Mitochondrial Fission and Promotes Pulmonary Arterial Hypertension: Mechanistic and Therapeutic Implications.","date":"2018","source":"Circulation","url":"https://pubmed.ncbi.nlm.nih.gov/29431643","citation_count":142,"is_preprint":false},{"pmid":"27660309","id":"PMC_27660309","title":"The role of Drp1 adaptor proteins MiD49 and MiD51 in mitochondrial fission: implications for human disease.","date":"2016","source":"Clinical science (London, England : 1979)","url":"https://pubmed.ncbi.nlm.nih.gov/27660309","citation_count":98,"is_preprint":false},{"pmid":"26432782","id":"PMC_26432782","title":"Drp1, Mff, Fis1, and MiD51 are coordinated to mediate mitochondrial fission during UV irradiation-induced apoptosis.","date":"2015","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/26432782","citation_count":98,"is_preprint":false},{"pmid":"24515348","id":"PMC_24515348","title":"Structural and functional analysis of MiD51, a dynamin receptor required for mitochondrial fission.","date":"2014","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/24515348","citation_count":85,"is_preprint":false},{"pmid":"24508339","id":"PMC_24508339","title":"The mitochondrial fission receptor MiD51 requires ADP as a cofactor.","date":"2014","source":"Structure 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MIEF1 also interacts with hFis1, and elevated hFis1 partially reverses MIEF1-induced fusion.\",\n      \"method\": \"Overexpression/knockdown with confocal imaging of mitochondrial morphology, co-immunoprecipitation, subcellular fractionation\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (Co-IP, KD/OE with defined morphological phenotype, fractionation), foundational paper replicated by subsequent studies\",\n      \"pmids\": [\"21701560\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"MiD49 and MiD51 form foci and rings around mitochondria, directly recruit Drp1 to the mitochondrial surface, and their knockdown reduces Drp1 association leading to unopposed fusion; overexpression sequesters Drp1 and causes fused tubules to associate with actin.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, overexpression with fluorescence microscopy\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP and KD with defined phenotype, replicated across multiple labs\",\n      \"pmids\": [\"21508961\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MiD49 and MiD51 can mediate Drp1 recruitment and mitochondrial fission independently of Fis1 and Mff, as shown in Fis1/Mff double-null cells; Fis1 and Mff regulate the number and size of Drp1 puncta on mitochondria.\",\n      \"method\": \"Genetic knockout (Fis1-null, Mff-null, Fis1/Mff-null cells), immunofluorescence of Drp1 puncta\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean genetic KO with specific phenotypic readout, highly cited and replicated\",\n      \"pmids\": [\"23283981\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MiD49/51 overexpression blocks fission by sequestering Drp1 specifically at mitochondria in a dominant-negative manner, causing unopposed fusion requiring mitofusins 1 and 2. MiD49/51 are not targeted to peroxisomes; when artificially targeted to peroxisomes or lysosomes, they specifically recruit Drp1 to those organelles.\",\n      \"method\": \"Overexpression at varying levels, mitofusin 1/2 KO epistasis, organelle retargeting constructs, fluorescence microscopy\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — epistasis experiments and organelle retargeting provide strong mechanistic evidence\",\n      \"pmids\": [\"23921378\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Crystal structure of the cytosolic domain of human MiD51 reveals a nucleotidyltransferase fold that lacks catalytic residues but specifically binds GDP and ADP. A region outside the nucleotidyltransferase fold is required for Drp1 recruitment and assembly of MiD51 into foci. MiD51 foci depend on Drp1 presence and are distributed to daughter organelles after fission.\",\n      \"method\": \"X-ray crystallography, nucleotide-binding assays, mutagenesis, live-cell imaging\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure with mutagenesis and functional validation in cells\",\n      \"pmids\": [\"24515348\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"MiD51 contains a nucleotidyltransferase domain that binds ADP with high affinity. MiD51 recruits Drp1 via a surface loop independently of ADP binding, but without nucleotide binding the recruited Drp1 cannot be activated for fission. Purified MiD51 strongly inhibits Drp1 assembly and GTP hydrolysis in the absence of ADP; ADP addition relieves this inhibition and promotes Drp1 assembly into spirals with enhanced GTP hydrolysis.\",\n      \"method\": \"X-ray crystallography, in vitro GTPase assay, Drp1 assembly assay with purified proteins, mutagenesis\",\n      \"journal\": \"Structure\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution in vitro with purified proteins, structure, and mutagenesis; replicated by Richter et al. 2014\",\n      \"pmids\": [\"24508339\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"MiD51 can suppress Mff-dependent enhancement of Drp1 GTPase activity. Proximity-based biotin labeling (BioID) shows close associations between MiD51, Mff, and Drp1, but not Fis1. Loss of MiD49 and MiD51 confers increased resistance to intrinsic apoptotic stimuli.\",\n      \"method\": \"BioID proximity labeling, CRISPR/Cas9 gene editing, in vitro Drp1 GTPase assay, apoptosis assays\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro GTPase assay combined with proximity labeling and clean KO cells\",\n      \"pmids\": [\"27076521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"During UV-induced apoptosis, the interaction between Drp1 and MiD51/MIEF1 decreases significantly, while interaction between Fis1 and MiD51/MIEF1 increases markedly, suggesting Fis1 competitively binds MiD51/MIEF1 to activate Drp1 indirectly. Phosphorylation of Drp1-Ser637 is essential for its interaction with Mff.\",\n      \"method\": \"Co-immunoprecipitation before and after UV irradiation, phospho-specific antibodies, western blotting\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP under apoptotic conditions; mechanistic model supported but not fully reconstituted\",\n      \"pmids\": [\"26432782\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MIEF1-MP (MIEF1 microprotein), encoded by a small ORF in the 5'UTR of MIEF1 mRNA, localizes to the mitochondrial matrix and interacts with the mitochondrial ribosome (mitoribosome). Loss of MIEF1-MP decreases mitochondrial translation rate; elevated MIEF1-MP increases translation rate.\",\n      \"method\": \"APEX2 proximity labeling, siRNA knockdown, overexpression, mitochondrial translation assay, subcellular fractionation\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — proximity labeling with functional validation (translation rate assay with KD and OE), multiple orthogonal methods\",\n      \"pmids\": [\"30215512\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The predominant translational product of the MIEF1 gene in human cells and colon tissue is not the canonical 463 aa MiD51 protein but the small 70 aa alternative ORF protein (altMiD51), as determined by absolute quantification with stable isotope-labeled peptides.\",\n      \"method\": \"Stable isotope-labeled peptide absolute quantification, parallel reaction monitoring mass spectrometry\",\n      \"journal\": \"Molecular & cellular proteomics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — quantitative mass spectrometry with internal standards; direct measurement\",\n      \"pmids\": [\"30181344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MIEF1 loss triggers imbalance of BCL2 family members on mitochondria, leading to BAX translocation to mitochondria, decreased mitochondrial membrane potential, and release of DIABLO/SMAC and cytochrome c. MIEF1 deficiency also impairs mitochondrial respiration, induces oxidative stress, and sensitizes cells to PINK1-PRKN-mediated mitophagy. Staurosporine-induced MIEF1 degradation occurs via the ubiquitin-proteasome system.\",\n      \"method\": \"CRISPR KO, siRNA knockdown, flow cytometry, western blotting, mitochondrial respiration assay, immunofluorescence\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with multiple defined cellular phenotypes, but single laboratory\",\n      \"pmids\": [\"30894073\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The interaction between Drp1 and MiD51 is regulated by GTP binding and depends on Drp1 polymerization. Two regions on MiD51 directly bind Drp1, and dimerization of MiD51 (dependent on residue C452) is required for mitochondrial dynamics regulation.\",\n      \"method\": \"Co-immunoprecipitation, mutagenesis (C452), GTP-binding assays, fluorescence microscopy\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — mutagenesis with Co-IP and functional readout, single laboratory\",\n      \"pmids\": [\"30703167\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In intact mammalian cells, Drp1 exists as a mixture of oligomeric assemblies. Mff preferentially binds higher-order Drp1 oligomers, while MIEFs (MIEF1 and MIEF2) bind a wider range including lower oligomeric states and recruit both active and inactive Drp1 mutants. Forced recruitment of Drp1 to mitochondria by MIEFs facilitates Drp1 oligomerization. MIEFs serve as a platform facilitating Drp1 binding to Mff; loss of MIEFs severely impairs the Drp1-Mff interaction.\",\n      \"method\": \"In vivo chemical crosslinking, co-immunoprecipitation, Drp1 oligomerization mutants, fluorescence microscopy in Mff/MIEF1/2-deficient cells\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo crosslinking with multiple Drp1 mutants and KO cell lines, single laboratory\",\n      \"pmids\": [\"34805137\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Long-chain acyl-CoA (LCACA) activates MiD51 by inducing its oligomerization via binding in the nucleotide-binding pocket (confirmed by a point mutation reducing binding and oligomerization). LCACA-induced MiD51 oligomers stimulate DRP1 GTPase activity; a LCACA-binding mutant fails to assemble into mitochondrial puncta or rescue MiD49/51 KD effects. MiD51 oligomers synergize with Mff but not actin filaments in DRP1 activation. Cellular oleic acid treatment promotes mitochondrial fission in an MiD49/51-dependent manner.\",\n      \"method\": \"In vitro GTPase assay, oligomerization assay, point mutagenesis, siRNA knockdown rescue, confocal microscopy, lipid-binding biochemistry\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with mutagenesis and cellular validation; identifies endogenous ligand\",\n      \"pmids\": [\"38594588\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Extracellular matrix stiffness, spatial confinement, and mechanical forces (including mouse skin stretching) regulate mitochondrial dynamics through MIEF1 phosphorylation. Actomyosin tension promotes MIEF1 phosphorylation, limiting DRP1 recruitment to mitochondria and reducing peri-mitochondrial F-actin formation and fission. DRP1- and MIEF1/2-dependent fission is required and sufficient to regulate YAP/TAZ, SREBP1/2, and NRF2 transcription factors, controlling cell proliferation, lipogenesis, antioxidant metabolism, and adipocyte differentiation in response to mechanical cues.\",\n      \"method\": \"Phosphorylation assays, DRP1/MIEF1/2 KO/KD with defined transcriptional and metabolic readouts, in vivo mouse skin stretching, live imaging, genetic epistasis\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods, in vivo validation, epistasis with transcriptional readouts; replicated across multiple mechanical stimuli\",\n      \"pmids\": [\"39433949\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Dominant heterozygous MIEF1 variants causing late-onset optic neuropathy do not disrupt MiD51 localization to the outer mitochondrial membrane or its oligomerization, but significantly disrupt mitochondrial network dynamics as shown by high-resolution live confocal imaging.\",\n      \"method\": \"Targeted sequencing, live confocal microscopy of mitochondrial dynamics, oligomerization assays in patient-derived variant cells\",\n      \"journal\": \"Molecular neurodegeneration\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional validation of disease variants with live imaging, single study\",\n      \"pmids\": [\"33632269\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"MAOA (monoamine oxidase A) physically interacts with MIEF1 and enhances MIEF1-DRP1 coupling; cortisol increases both MIEF1 and DRP1-Ser616 phosphorylation, driving excessive mitochondrial fission and trabecular meshwork fibrosis. Knockdown of MAOA or MIEF1 reduces oxidative stress, mitochondrial fragmentation, and extracellular matrix remodeling.\",\n      \"method\": \"Co-immunoprecipitation, molecular docking, molecular dynamics simulations, siRNA knockdown, western blotting, confocal microscopy\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP with computational support and functional KD readout, single study\",\n      \"pmids\": [\"41579974\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MIEF1 (MiD51) is an outer mitochondrial membrane protein that recruits cytosolic DRP1 to mitochondria via a dedicated surface loop, then modulates DRP1 activity: in the absence of metabolic cofactors (ADP or long-chain acyl-CoA), MIEF1 sequesters and inhibits DRP1; binding of ADP or LCACA to MIEF1's nucleotidyltransferase-fold domain induces MIEF1 oligomerization and relieves inhibition to promote DRP1 assembly and GTPase-driven fission. Actomyosin-mediated phosphorylation of MIEF1 limits DRP1 recruitment during mechanotransduction, making MIEF1-dependent fission a signaling node that controls YAP/TAZ, SREBP, and NRF2 transcription. Additionally, the MIEF1 locus encodes a microprotein (MIEF1-MP) that localizes to the mitochondrial matrix and stimulates mitoribosome-dependent translation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MIEF1 (MiD51) is an outer mitochondrial membrane receptor that governs mitochondrial fission by recruiting and regulating the dynamin-related GTPase DRP1, acting as a metabolic and mechanical signaling node. Its cytosolic nucleotidyltransferase-fold domain binds ADP and long-chain acyl-CoA (LCACA); in the ligand-free state MIEF1 sequesters DRP1 and inhibits its GTPase activity, whereas ADP or LCACA binding induces MIEF1 oligomerization that relieves inhibition, promotes DRP1 assembly into fission-competent spirals, and synergizes with Mff [PMID:24508339, PMID:38594588, PMID:34805137]. Actomyosin-dependent phosphorylation of MIEF1 limits DRP1 recruitment in response to extracellular matrix stiffness and mechanical forces, coupling mitochondrial fission to YAP/TAZ, SREBP, and NRF2 transcriptional programs that control proliferation, lipogenesis, and antioxidant metabolism [PMID:39433949]. The MIEF1 locus additionally encodes a small open reading frame (MIEF1-MP/altMiD51) whose 70-amino-acid microprotein localizes to the mitochondrial matrix, interacts with the mitoribosome, and stimulates mitochondrial translation [PMID:30215512, PMID:30181344]. Dominant heterozygous MIEF1 variants cause late-onset optic neuropathy by disrupting mitochondrial network dynamics without abolishing membrane targeting [PMID:33632269].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Before MIEF1 was identified, DRP1 recruitment to mitochondria was attributed to Fis1 and Mff; the discovery that MIEF1 directly recruits DRP1 independently of these receptors established an alternative, parallel recruitment pathway and revealed that overexpression paradoxically inhibits fission.\",\n      \"evidence\": \"Overexpression/knockdown with Co-IP, subcellular fractionation, and confocal imaging in mammalian cells (two independent labs)\",\n      \"pmids\": [\"21701560\", \"21508961\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of MIEF1–DRP1 interaction unknown\", \"Whether MIEF1 alone is sufficient for fission in vivo unresolved\", \"Relationship between MiD49 and MiD51 redundancy not defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"The question of whether MIEF1/MiD51 and MiD49 can execute DRP1-dependent fission without Fis1 and Mff was answered: genetic elimination of Fis1 and Mff demonstrated that MiD proteins constitute a functionally independent receptor pathway.\",\n      \"evidence\": \"Fis1/Mff double-knockout cells with immunofluorescence of DRP1 puncta; organelle retargeting of MiD to peroxisomes/lysosomes\",\n      \"pmids\": [\"23283981\", \"23921378\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct biochemical mechanism by which MIEF1 modulates DRP1 activity unknown\", \"Role of nucleotide binding unexplored\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Crystallography resolved a central paradox—how MIEF1 both recruits and inhibits DRP1—by showing that its nucleotidyltransferase-fold domain binds ADP, and that a separate surface loop recruits DRP1; without ADP, MIEF1 inhibits DRP1 assembly and GTPase activity, while ADP binding relieves inhibition and promotes fission-competent DRP1 spirals.\",\n      \"evidence\": \"X-ray crystallography, nucleotide-binding assays, in vitro reconstitution with purified proteins, mutagenesis\",\n      \"pmids\": [\"24515348\", \"24508339\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the physiological metabolite controlling MIEF1 in cells not established\", \"Oligomerization state of MIEF1 and its regulation not defined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Functional interplay between MIEF1 and Mff was clarified: MIEF1 suppresses Mff-dependent enhancement of DRP1 GTPase activity, and proximity labeling confirmed close association of MIEF1, Mff, and DRP1 in intact cells; loss of MiD49/51 increased resistance to intrinsic apoptosis.\",\n      \"evidence\": \"BioID proximity labeling, CRISPR knockout, in vitro DRP1 GTPase assay, apoptosis assays\",\n      \"pmids\": [\"27076521\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How MIEF1 physically integrates with Mff on the same DRP1 oligomer unclear\", \"Apoptotic role not distinguished from general fission defect\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"A previously unrecognized translational product of the MIEF1 locus—the 70-amino-acid microprotein MIEF1-MP (altMiD51)—was discovered to localize to the mitochondrial matrix, interact with the mitoribosome, and regulate mitochondrial translation, representing a dual-function locus.\",\n      \"evidence\": \"APEX2 proximity labeling, stable isotope-labeled peptide absolute quantification, knockdown and overexpression with mitochondrial translation assays\",\n      \"pmids\": [\"30215512\", \"30181344\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific mitoribosome subunit contact site not identified\", \"Whether MIEF1-MP affects specific mitochondrial-encoded transcripts unknown\", \"Functional coupling between MiD51 and MIEF1-MP products unexamined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"MIEF1 loss was shown to perturb mitochondrial homeostasis beyond fission—imbalancing BCL2 family members, causing BAX translocation, cytochrome c release, impaired respiration, and sensitization to PINK1-PRKN mitophagy—linking MIEF1 to mitochondrial quality control.\",\n      \"evidence\": \"CRISPR knockout, flow cytometry, mitochondrial respiration assay, western blotting, immunofluorescence\",\n      \"pmids\": [\"30894073\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether apoptotic sensitization is a direct effect or secondary to chronic fission imbalance is unclear\", \"Single laboratory; independent replication needed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"In vivo crosslinking revealed that MIEFs bind a broader range of DRP1 oligomeric states than Mff and serve as platforms facilitating DRP1 oligomerization and subsequent handoff to Mff, resolving how these receptors cooperate hierarchically.\",\n      \"evidence\": \"In vivo chemical crosslinking, Co-IP with DRP1 oligomerization mutants, Mff/MIEF1/2-deficient cell lines\",\n      \"pmids\": [\"34805137\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural model of the MIEF1-DRP1-Mff ternary complex lacking\", \"Stoichiometry of the handoff not determined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Dominant heterozygous MIEF1 variants were linked to late-onset optic neuropathy, establishing the first Mendelian disease association and demonstrating that variants disrupting mitochondrial network dynamics without affecting membrane targeting or oligomerization can cause neurodegeneration.\",\n      \"evidence\": \"Targeted sequencing in optic neuropathy patients, live confocal imaging of mitochondrial dynamics, oligomerization assays of variant proteins\",\n      \"pmids\": [\"33632269\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Precise biochemical defect of disease variants (e.g. DRP1 binding affinity) not measured\", \"Penetrance and genotype-phenotype correlation require larger cohorts\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Long-chain acyl-CoA was identified as a second endogenous activating ligand of MIEF1, binding the same nucleotide pocket to induce oligomerization and stimulate DRP1 GTPase activity, linking fatty acid metabolism to mitochondrial fission through MiD51.\",\n      \"evidence\": \"In vitro GTPase and oligomerization assays with purified proteins, point mutagenesis of LCACA-binding site, siRNA rescue, oleic acid cellular treatment\",\n      \"pmids\": [\"38594588\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of ADP vs. LCACA under physiological conditions unknown\", \"Whether other acyl-CoA chain lengths have distinct effects untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"MIEF1 was established as a mechanotransduction effector: actomyosin tension phosphorylates MIEF1, limiting DRP1 recruitment and fission, and this pathway is necessary and sufficient to regulate YAP/TAZ, SREBP, and NRF2 transcription in response to matrix stiffness.\",\n      \"evidence\": \"Phosphorylation assays, DRP1/MIEF1/2 KO/KD with transcriptional and metabolic readouts, in vivo mouse skin stretching, genetic epistasis\",\n      \"pmids\": [\"39433949\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase directly phosphorylating MIEF1 not identified\", \"Specific phosphorylation sites and their individual contributions not mapped\", \"How mitochondrial fission state is decoded by transcription factors mechanistically unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include: the identity of the kinase that phosphorylates MIEF1 downstream of actomyosin tension; a structural model of the MIEF1-DRP1-Mff ternary complex; the physiological balance between ADP and LCACA in regulating MIEF1 oligomerization; and whether MIEF1-MP functionally coordinates with MiD51 to integrate mitochondrial translation and dynamics.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No kinase identified for mechanotransduction-dependent MIEF1 phosphorylation\", \"No ternary structural model of MIEF1-DRP1-Mff\", \"Functional interplay between MiD51 and MIEF1-MP gene products untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 5, 6, 12, 13]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 2, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0, 1, 4, 8, 15]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [0, 1, 2, 5, 13, 14]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [6, 7, 10]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [13, 14]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [14]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [8, 9]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"DNM1L\",\n      \"MFF\",\n      \"FIS1\",\n      \"MIEF2\",\n      \"MAOA\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}