{"gene":"MTFP1","run_date":"2026-06-10T02:59:51","timeline":{"discoveries":[{"year":2004,"finding":"MTFP1 (MTP18) was identified as a nuclear-encoded mitochondrial protein whose mRNA and protein expression is dependent on PI 3-kinase activity. Knockdown via antisense molecules caused cytochrome c release and apoptosis, and reduced MTP18 levels resulted in a highly interconnected mitochondrial reticulum, while overexpression induced punctate mitochondrial morphology, establishing MTP18 as a downstream target of PI3K signaling that controls mitochondrial morphology and cell viability.","method":"Antisense knockdown, confocal microscopy, biochemical fractionation, overexpression studies in PC-3, HaCaT, and COS-7 cells","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (knockdown, overexpression, fractionation, cytochrome c release assay) in single lab","pmids":["15155745"],"is_preprint":false},{"year":2005,"finding":"MTP18 functions as an essential intramitochondrial component of the mitochondrial division apparatus: overexpression induced mitochondrial fragmentation that was blocked by co-expression of Mfn1 or dominant-negative Drp1(K38A), RNAi-mediated knockdown produced highly fused mitochondria, and MTP18 knockdown blocked fission induced by hFis1 overexpression, placing MTP18 downstream of or parallel to hFis1 and requiring Drp1 for its fission activity.","method":"RNAi knockdown, overexpression, genetic epistasis with Mfn1, dominant-negative Drp1(K38A), and hFis1 co-expression; confocal microscopy of mitochondrial morphology","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal genetic epistasis with multiple fission/fusion proteins, replicated knockdown and overexpression, functionally validated pathway placement","pmids":["15985469"],"is_preprint":false},{"year":2017,"finding":"mTORC1 stimulates translation of MTFP1 via the eIF4E/4E-BP pathway to promote mitochondrial fission. MTFP1 expression is coupled to pro-fission phosphorylation and mitochondrial recruitment of DRP1. Active-site mTOR inhibitors reduce MTFP1 translation (mediated by 4E-BPs), causing mitochondrial hyperfusion; uncoupling MTFP1 levels from mTORC1/4E-BP upon mTOR inhibition blocks hyperfusion and converts mTOR inhibitor action from cytostatic to cytotoxic.","method":"Polysome profiling, mTOR inhibitor treatment, 4E-BP overexpression/knockdown, DRP1 phosphorylation and mitochondrial recruitment assays, cell viability and apoptosis readouts","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (translational control assays, epistasis with 4E-BPs, DRP1 recruitment, apoptosis), mechanistic pathway placement in single rigorous study","pmids":["28918902"],"is_preprint":false},{"year":2017,"finding":"MTFP1 knockdown prevents DRP1 (Dnm1l) accumulation at mitochondria and suppresses doxorubicin-induced mitochondrial fission and apoptosis in cardiac myocytes; conversely, MTFP1 overexpression sensitizes cells to doxorubicin-induced fission and apoptosis, establishing MTFP1 as a pro-fission effector acting upstream of DRP1 mitochondrial translocation.","method":"siRNA knockdown, overexpression, mitochondrial morphology imaging, apoptosis assays, DRP1 mitochondrial localization by fractionation/immunofluorescence in HL-1 cardiac myocytes","journal":"Journal of cellular and molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockdown and overexpression with defined phenotypic readout and DRP1 localization, single lab","pmids":["28643438"],"is_preprint":false},{"year":2017,"finding":"In gastric cancer cells, MTP18 overexpression enriches DRP1 accumulation at mitochondria and mediates doxorubicin-induced mitochondrial fission and apoptosis; MTP18 expression is downregulated during DOX treatment, suggesting its downregulation contributes to chemoresistance.","method":"Overexpression, mitochondrial fragmentation assay, DRP1 mitochondrial accumulation analysis, apoptosis assays in gastric cancer cells","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — overexpression and DRP1 localization, mechanistic follow-up, single lab with multiple readouts","pmids":["28915614"],"is_preprint":false},{"year":2018,"finding":"miR-668 is induced in ischemic AKI via HIF-1 (a functional HIF-1 binding site was identified in the miR-668 promoter) and directly represses MTP18, as validated by luciferase reporter assay and RISC immunoprecipitation-RNA sequencing; MTP18 knockdown suppressed mitochondrial fragmentation and apoptosis in renal tubular cells, positioning MTP18 as a downstream effector of HIF-1/miR-668 in mitochondrial dynamics during ischemia.","method":"Anti-miR/mimic transfection, luciferase microRNA target reporter assay, RISC immunoprecipitation + RNA-seq, MTP18 knockdown, mitochondrial morphology and apoptosis assays, in vivo mouse AKI model","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (RISC-IP/RNA-seq, luciferase reporter, in vivo knockdown/mimic), replicated in cells and mice","pmids":["30325740"],"is_preprint":false},{"year":2019,"finding":"In retinal ganglion cells (RGCs), MTP18/MTFP1 is critical for maintaining mitochondrial size and volume; MTP18 expression is regulated by KLF7 and KLF9 transcription factors, and MTP18 knockdown promotes axon growth, placing MTP18 as a downstream component of KLF-mediated axon regenerative signaling.","method":"siRNA knockdown, overexpression, mitochondrial morphology imaging, axon growth assays, transcription factor regulation analysis in RGCs","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockdown with defined phenotypic readouts and upstream TF identification, single lab","pmids":["31337818"],"is_preprint":false},{"year":2020,"finding":"In Xenopus tropicalis, the Mtfp1 gene is directly transcriptionally activated by thyroid hormone (T3) via thyroid hormone receptors (TRs) binding to a T3-response element (TRE) within the first intron, mediating local histone H3K79 methylation and RNA polymerase recruitment; Mtfp1 promoter activation by T3 was confirmed in a reconstituted frog oocyte system and found to require the intronic TRE.","method":"ChIP assay for TR binding and H3K79 methylation, RNA polymerase recruitment assay, reconstituted frog oocyte transcription assay, TRE deletion/mutation analysis","journal":"General and comparative endocrinology","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — ChIP and reconstituted oocyte system with TRE validation, single lab, ortholog (Xenopus)","pmids":["32827515"],"is_preprint":false},{"year":2022,"finding":"A small-molecule inhibitor (S28) of MTP18 induces stress-induced mitochondrial hyperfusion (SIMH) by inhibiting MTP18-mediated fission (decreased p-DRP1, increased Mfn1), leading to loss of mitochondrial membrane potential, mitochondrial superoxide generation, lysosomal membrane permeabilization (LMP), impaired autophagosome-lysosome fusion, and intrinsic apoptosis; MTP18 overexpression restored mitochondrial fission, induced mitophagy, and suppressed LMP and apoptosis.","method":"Small-molecule inhibition, overexpression, mitochondrial morphology imaging, p-DRP1 western blot, membrane potential assay, superoxide detection, lysosomal pH and LMP assays, apoptosis assays in oral cancer cells","journal":"Free radical biology & medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological inhibition plus overexpression with mechanistic pathway tracing, single lab","pmids":["35985563"],"is_preprint":false},{"year":2023,"finding":"MTP18/MTFP1 functions as a mitophagy receptor: it contains an LC3-interacting region (LIR) that directly interacts with MAP1LC3 family members to target dysfunctional mitochondria to autophagosomes; LIR mutation (mLIR) abolishes this interaction and suppresses mitophagy; PINK1/Parkin deficiency abrogates MTP18-dependent mitophagy, and Parkin-mediated proteasomal degradation of the outer mitochondrial membrane is required for effective mitophagy downstream of MTP18.","method":"LIR motif mutation, co-immunoprecipitation of MTP18 with LC3 family members, PINK1/Parkin knockdown, CCCP-induced mitophagy assays, TOM20/COX IV degradation analysis, apoptosis assays in FaDu oral cancer cells","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — LIR mutagenesis combined with co-IP, epistasis with PINK1/Parkin, multiple orthogonal readouts of mitophagy","pmids":["37313742"],"is_preprint":false},{"year":2023,"finding":"Hepatocyte-specific deletion of Mtfp1 in mice is physiologically benign but leads to upregulation of oxidative phosphorylation (OXPHOS) activity and mitochondrial respiration independently of mitochondrial biogenesis, and protects against high-fat diet-induced steatosis. Additionally, Mtfp1 deletion inhibits mitochondrial permeability transition pore (mPTP) opening, conferring protection against apoptotic liver damage.","method":"Liver-specific Mtfp1 knockout mice, respirometry (Seahorse), proteomics, high-fat diet metabolic phenotyping, mPTP opening assay, ex vivo apoptosis assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional knockout with multiple orthogonal metabolic and functional assays in vivo and ex vivo, single rigorous study","pmids":["38123539"],"is_preprint":false},{"year":2024,"finding":"MTFP1 is an inner mitochondrial membrane (IMM) protein that negatively regulates IMM fusion. Manipulation of MTFP1 levels modulates mtDNA copy number (CN). Mechanistically, MTFP1 inhibits mitochondrial fusion to isolate and exclude damaged IMM subdomains, which are then segregated by peripheral fission into small MTFP1-enriched mitochondria (SMEM) that are targeted for autophagic degradation; this MTFP1-dependent IMM quality control is essential for basal nucleoid recycling and maintaining adequate mtDNA levels.","method":"MTFP1 overexpression/knockout, mitochondrial fusion assays, super-resolution and live-cell imaging, mtDNA CN measurement, autophagy inhibition experiments, SMEM isolation and characterization","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods (live imaging, functional fusion assays, mtDNA CN quantification, autophagic pathway epistasis) in single rigorous study","pmids":["38851188"],"is_preprint":false},{"year":2024,"finding":"HIF1A directly binds the MTFP1 promoter (validated by ChIP assay) and upregulates MTFP1 expression; MTFP1 overexpression promotes lung squamous cell carcinoma cell proliferation and metastasis by activating the glycolytic pathway.","method":"ChIP assay, western blot, cell proliferation/colony formation/migration assays, glycolysis pathway analysis in LUSC cells","journal":"Heliyon","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP confirmation of HIF1A binding plus functional cell assays, single lab","pmids":["38689964"],"is_preprint":false},{"year":2025,"finding":"PPA2 (inorganic pyrophosphatase, matrix-localized) directly interacts with MTFP1 and activates mitochondrial fission signaling by upregulating phosphorylated DNM1L S616 and its mitochondrial translocation; MTFP1 knockdown in PPA2-overexpressing cells abolishes DNM1L activation and fission. PPA2 utilizes the C-terminal LIR of MTFP1 for mitophagy-mediated clearance of damaged mitochondria, and PPA2 directs midzone fission (via MFF-DNM1L) for mitochondrial proliferation or peripheral fission (via FIS1-DNM1L) for mitophagy under stress.","method":"Co-immunoprecipitation of PPA2 with MTFP1, MTFP1 siRNA knockdown epistasis, overexpression studies, mitochondrial morphology imaging, DNM1L phosphorylation assays, CCCP-induced mitophagy assays, LIR mutation analysis","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus epistasis knockdown, multiple fission site readouts, single lab","pmids":["40873007"],"is_preprint":false},{"year":2025,"finding":"In zebrafish, the transcription factor Zbtb48 positively regulates Mtfp1 expression; zbtb48 knockout resulted in downregulation of mtfp1 at both mRNA and protein levels, particularly in ovary and testis, suggesting mtfp1 is an evolutionarily conserved transcriptional target of Zbtb48.","method":"CRISPR-Cas9 zbtb48 knockout zebrafish, RT-qPCR, western blot for Mtfp1 protein levels in gonads","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout with mRNA and protein validation, single lab, ortholog (zebrafish)","pmids":["39987415"],"is_preprint":false},{"year":2025,"finding":"In C. elegans, loss of mtp-18 increases longevity and stress resistance; mtp-18-mediated longevity requires the Forkhead transcription factor DAF-16 but is not mediated through the canonical IIS (insulin/IGF-1 signaling) cascade; MTP-18 shows unique genetic interactions with components of the mitochondrial electron transport chain, specifically coenzyme Q and cytochrome c mobile electron carrier system.","method":"mtp-18 loss-of-function mutants, lifespan assays, epistasis with daf-16 and IIS pathway mutants, genetic interaction with ETC component genes in C. elegans","journal":"Biogerontology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis in C. elegans with multiple pathway components, single lab, ortholog","pmids":["41832346"],"is_preprint":false},{"year":2025,"finding":"MTFP1 acts as a novel ATP synthase modulator through its interaction with multiple ATP synthase subunits (identified by GST pull-down), thereby enhancing oxidative phosphorylation; increased mitochondrial fission and ROS production downstream of MTFP1 upregulates SLC1A5 expression via the PI3K/AKT/c-MYC pathway, promoting glutamine uptake and impairing CD8+ T cell antitumor responses in pancreatic cancer liver metastasis.","method":"CRISPR loss-of-function screen, GST pull-down assay for ATP synthase subunit interaction, metabolic flux analysis, single-cell RNA-seq, spatial metabolomics, in vivo mouse models, PDAC organoids","journal":"Gut","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — GST pull-down for ATP synthase interaction plus functional metabolic assays and in vivo models, single lab","pmids":["41663153"],"is_preprint":false},{"year":2025,"finding":"MISO (Mitochondrial Inner membrane Subdomain Organizer) is required for SMEM formation; SMEM functionality requires MISO-dependent recruitment of MTFP1 and subsequent engagement of the FIS1-DRP1 fission machinery; MISO knockout completely abolishes SMEM generation, establishing MTFP1 as a downstream effector recruited by MISO to form SMEM and mediate peripheral fission and lysosomal mtDNA degradation.","method":"MISO knockout (Drosophila and mammalian cells), live-cell imaging of SMEM, MTFP1 localization assays, FIS1/DRP1 epistasis, lysosomal mtDNA degradation assays","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout with live imaging and pathway epistasis, preprint not yet peer-reviewed","pmids":["bio_10.1101_2025.01.05.631328"],"is_preprint":true},{"year":2026,"finding":"MTFP1 is essential for normal glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells; β-cell-specific MTFP1 knockout mice develop glucose intolerance, with sharply reduced oxidative phosphorylation and ATP production, disrupted mitochondrial cristae structure, and reduced ER-mitochondria contact surface. MTFP1 overexpression in mouse and human islets improved mitochondrial respiration and GSIS. MTFP1 was identified as a downstream effector of miR-125b: MTFP1 downregulation blocked the positive effects of miR-125b elimination on GSIS and mitochondrial respiration.","method":"β-cell-specific conditional knockout mice, glucose tolerance tests, respirometry, cristae ultrastructure (EM), ER-mitochondria contact quantification, MTFP1 overexpression in human islets, miR-125b epistasis experiments","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional knockout with multiple orthogonal functional assays and overexpression rescue, preprint not yet peer-reviewed","pmids":["41648185"],"is_preprint":true}],"current_model":"MTFP1 (MTP18) is an inner mitochondrial membrane protein that promotes mitochondrial fission by stimulating pro-fission phosphorylation and mitochondrial recruitment of DRP1; its expression is translationally controlled by the mTORC1/4E-BP/eIF4E axis and transcriptionally by HIF-1α and ZBTB48; it also functions as a mitophagy receptor via an LIR motif that engages LC3/MAP1LC3 family members in a PINK1/Parkin-dependent manner, and it negatively regulates IMM fusion to isolate damaged membrane subdomains into small MTFP1-enriched mitochondria (SMEM) for autophagic degradation, thereby controlling mtDNA copy number, OXPHOS activity, and cell fate decisions including apoptosis and insulin secretion."},"narrative":{"mechanistic_narrative":"MTFP1 (MTP18) is a nuclear-encoded inner mitochondrial membrane protein that promotes mitochondrial fission and governs mitochondrial morphology, quality control, and cell fate [PMID:15155745, PMID:15985469, PMID:38851188]. Functionally it acts upstream of DRP1, driving pro-fission phosphorylation (p-DRP1 S616) and mitochondrial recruitment of DRP1; overexpression fragments the network while knockdown produces a hyperfused reticulum, and its fission activity is genetically dependent on DRP1 and antagonized by Mfn1 [PMID:15985469, PMID:28918902]. MTFP1 also enforces inner-membrane quality control: it negatively regulates IMM fusion to isolate damaged subdomains, which are segregated by peripheral fission into small MTFP1-enriched mitochondria (SMEM) and degraded by autophagy, a process required for nucleoid recycling and maintenance of mtDNA copy number [PMID:38851188]. MTFP1 doubles as a mitophagy receptor through an LC3-interacting region (LIR) that binds MAP1LC3 family members to deliver dysfunctional mitochondria to autophagosomes in a PINK1/Parkin-dependent manner [PMID:37313742]. MTFP1 abundance is set by multiple inputs: translationally by the mTORC1/4E-BP/eIF4E axis [PMID:28918902] and transcriptionally by HIF-1α [PMID:38689964] and the conserved factor ZBTB48 [PMID:39987415]. Through these activities MTFP1 modulates OXPHOS and apoptosis: loss de-represses respiration, blocks mPTP opening, and protects against steatosis and apoptotic damage [PMID:38123539], and it is required for glucose-stimulated insulin secretion in β-cells [PMID:41648185]. MTFP1 interacts with ATP synthase subunits and with PPA2, links to fission-driven metabolic reprogramming in cancer, and is recruited to nascent SMEM by MISO [PMID:40873007, PMID:41663153, PMID:bio_10.1101_2025.01.05.631328].","teleology":[{"year":2004,"claim":"Established MTP18 as a PI3K-dependent mitochondrial protein controlling network morphology and viability, framing it as a signaling-responsive regulator rather than a structural curiosity.","evidence":"Antisense knockdown, overexpression, fractionation, and cytochrome c release in PC-3/HaCaT/COS-7 cells","pmids":["15155745"],"confidence":"Medium","gaps":["Did not define molecular activity or partners","Mechanism linking PI3K to morphology unresolved","Single-lab phenotype"]},{"year":2005,"claim":"Placed MTP18 in the fission machinery by showing its activity requires DRP1 and is antagonized by Mfn1/fusion, answering whether it acts in division versus fusion.","evidence":"RNAi, overexpression, and genetic epistasis with Mfn1, dominant-negative Drp1(K38A), and hFis1 by confocal imaging","pmids":["15985469"],"confidence":"High","gaps":["Did not establish direct biochemical interaction with DRP1","Exact ordering relative to hFis1 ambiguous"]},{"year":2017,"claim":"Defined how MTFP1 levels are set and translated that control into fission, showing mTORC1/4E-BP-driven translation couples MTFP1 abundance to DRP1 recruitment and cell fate.","evidence":"Polysome profiling, mTOR inhibition, 4E-BP manipulation, DRP1 phosphorylation/recruitment, and apoptosis assays","pmids":["28918902","28643438","28915614"],"confidence":"High","gaps":["Whether MTFP1 directly modifies DRP1 not shown","Tissue-specific relevance of translational control untested"]},{"year":2018,"claim":"Identified transcriptional/post-transcriptional repression of MTP18 by HIF-1/miR-668, showing MTFP1 is a tunable effector of ischemic mitochondrial dynamics.","evidence":"RISC-IP/RNA-seq, luciferase reporter, and in vivo knockdown/mimic in a mouse AKI model","pmids":["30325740"],"confidence":"High","gaps":["Does not address direct fission machinery interactions","Generalizability beyond renal ischemia unknown"]},{"year":2019,"claim":"Showed MTP18 maintains mitochondrial size and is set by KLF transcription factors, linking its dosage to neuronal axon growth.","evidence":"siRNA, overexpression, mitochondrial imaging, and axon growth assays in retinal ganglion cells","pmids":["31337818"],"confidence":"Medium","gaps":["Mechanism connecting size control to axon growth unresolved","Single-lab observation"]},{"year":2020,"claim":"Demonstrated direct thyroid-hormone-receptor transcriptional activation of Mtfp1 via an intronic TRE, adding hormonal control to its regulatory repertoire.","evidence":"ChIP for TR binding and H3K79 methylation, RNA Pol recruitment, and reconstituted frog oocyte assay with TRE mutation","pmids":["32827515"],"confidence":"Medium","gaps":["Xenopus ortholog; human conservation not tested here","Downstream physiological output not measured"]},{"year":2022,"claim":"Used pharmacological inhibition to show MTP18-mediated fission gates a stress axis spanning hyperfusion, lysosomal permeabilization, and apoptosis.","evidence":"Small-molecule (S28) inhibition plus overexpression with membrane potential, superoxide, LMP, and apoptosis readouts in oral cancer cells","pmids":["35985563"],"confidence":"Medium","gaps":["Inhibitor specificity for MTP18 not fully validated","Direct molecular target engagement unclear"]},{"year":2023,"claim":"Revealed a second function for MTFP1 as a mitophagy receptor, showing an LIR motif directly engages LC3 to deliver mitochondria to autophagosomes downstream of PINK1/Parkin.","evidence":"LIR mutagenesis, co-IP with LC3 family members, PINK1/Parkin knockdown, CCCP mitophagy and OMM degradation assays","pmids":["37313742"],"confidence":"High","gaps":["Structural basis of LIR engagement not solved","Coordination of fission vs receptor roles unresolved"]},{"year":2023,"claim":"Defined the in vivo metabolic consequence of MTFP1 loss, showing it restrains OXPHOS and mPTP opening, linking fission control to steatosis and apoptotic protection.","evidence":"Liver-specific knockout mice with respirometry, proteomics, high-fat diet phenotyping, and mPTP assays","pmids":["38123539"],"confidence":"High","gaps":["Mechanism by which MTFP1 suppresses OXPHOS not defined","Direct mPTP component interaction unknown"]},{"year":2024,"claim":"Established MTFP1 as an inner-membrane quality-control factor that segregates damaged subdomains into SMEM for autophagic mtDNA recycling, unifying its fission and degradation roles.","evidence":"Overexpression/knockout, fusion assays, super-resolution/live imaging, mtDNA copy-number quantification, and autophagy inhibition","pmids":["38851188","38689964"],"confidence":"High","gaps":["How MTFP1 selectively recognizes damaged IMM unresolved","Link between SMEM and mtDNA recycling mechanistically incomplete"]},{"year":2025,"claim":"Identified direct protein partners (PPA2, ATP synthase subunits) and conserved regulators (ZBTB48), connecting MTFP1 to fission-site selection, OXPHOS modulation, and cancer/longevity phenotypes.","evidence":"Co-IP and GST pull-downs, siRNA epistasis, metabolic flux, in vivo cancer models, and ortholog knockouts in zebrafish and C. elegans","pmids":["40873007","41663153","39987415","41832346"],"confidence":"Medium","gaps":["Direct binding interfaces not mapped","Whether ATP synthase modulation is direct or fission-dependent unclear","Ortholog phenotypes' human relevance untested"]},{"year":2026,"claim":"Extended MTFP1's physiological role to β-cell insulin secretion and to MISO-dependent SMEM assembly, defining recruitment hierarchy and a metabolic-endocrine function (preprints).","evidence":"β-cell conditional knockout, respirometry, EM cristae/ER-mito contacts, miR-125b epistasis; MISO knockout with live imaging and FIS1/DRP1 epistasis (preprints)","pmids":["41648185","bio_10.1101_2025.01.05.631328"],"confidence":"Medium","gaps":["Preprints not peer-reviewed","Molecular nature of MISO–MTFP1 recruitment undefined","How cristae/ER-mito defects arise from MTFP1 loss unresolved"]},{"year":null,"claim":"How a single IMM protein mechanistically toggles between promoting fission, restraining fusion, and acting as a mitophagy receptor, and the structural basis of its DRP1/LC3/PPA2/ATP-synthase interactions, remain open.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of MTFP1 or its complexes","Direct enzymatic/biochemical activity undefined","Regulatory switch between fission and receptor modes unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2,3]},{"term_id":"GO:0140097","term_label":"catalytic activity, acting on DNA","supporting_discovery_ids":[11]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,16]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0,11]}],"pathway":[{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[1,11]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[9,11]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[0,10]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[10,16]}],"complexes":[],"partners":["DNM1L","MAP1LC3","PPA2","MISO"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UDX5","full_name":"Mitochondrial fission process protein 1","aliases":["Mitochondrial 18 kDa protein","MTP18"],"length_aa":166,"mass_kda":18.0,"function":"Involved in the mitochondrial division probably by regulating membrane fission. Loss-of-function induces the release of cytochrome c, which activates the caspase cascade and leads to apoptosis","subcellular_location":"Mitochondrion inner membrane","url":"https://www.uniprot.org/uniprotkb/Q9UDX5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MTFP1","classification":"Not Classified","n_dependent_lines":19,"n_total_lines":1208,"dependency_fraction":0.015728476821192054},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MTFP1","total_profiled":1310},"omim":[{"mim_id":"610235","title":"MITOCHONDRIAL FISSION PROCESS 1; MTFP1","url":"https://www.omim.org/entry/610235"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Mitochondria","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MTFP1"},"hgnc":{"alias_symbol":["MTP18","HSPC242"],"prev_symbol":[]},"alphafold":{"accession":"Q9UDX5","domains":[{"cath_id":"1.20.58","chopping":"13-155","consensus_level":"high","plddt":92.4236,"start":13,"end":155}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UDX5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UDX5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UDX5-F1-predicted_aligned_error_v6.png","plddt_mean":86.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MTFP1","jax_strain_url":"https://www.jax.org/strain/search?query=MTFP1"},"sequence":{"accession":"Q9UDX5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UDX5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UDX5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UDX5"}},"corpus_meta":[{"pmid":"28918902","id":"PMC_28918902","title":"mTOR Controls Mitochondrial Dynamics and Cell Survival via MTFP1.","date":"2017","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/28918902","citation_count":295,"is_preprint":false},{"pmid":"28498369","id":"PMC_28498369","title":"Circular RNA mediates cardiomyocyte death via miRNA-dependent upregulation of MTP18 expression.","date":"2017","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/28498369","citation_count":287,"is_preprint":false},{"pmid":"15985469","id":"PMC_15985469","title":"The mitochondrial protein MTP18 contributes to mitochondrial fission in mammalian cells.","date":"2005","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/15985469","citation_count":195,"is_preprint":false},{"pmid":"15155745","id":"PMC_15155745","title":"Knockdown of MTP18, a novel phosphatidylinositol 3-kinase-dependent protein, affects mitochondrial morphology and induces apoptosis.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15155745","citation_count":124,"is_preprint":false},{"pmid":"30325740","id":"PMC_30325740","title":"MicroRNA-668 represses MTP18 to preserve mitochondrial dynamics in ischemic acute kidney injury.","date":"2018","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/30325740","citation_count":114,"is_preprint":false},{"pmid":"38851188","id":"PMC_38851188","title":"MTFP1 controls mitochondrial fusion to regulate inner membrane quality control and maintain mtDNA levels.","date":"2024","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/38851188","citation_count":86,"is_preprint":false},{"pmid":"34102054","id":"PMC_34102054","title":"Genetically Encoded, pH-Sensitive mTFP1 Biosensor for Probing Lysosomal pH.","date":"2021","source":"ACS sensors","url":"https://pubmed.ncbi.nlm.nih.gov/34102054","citation_count":64,"is_preprint":false},{"pmid":"28643438","id":"PMC_28643438","title":"Knockdown of Mtfp1 can minimize doxorubicin cardiotoxicity by inhibiting Dnm1l-mediated mitochondrial fission.","date":"2017","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/28643438","citation_count":38,"is_preprint":false},{"pmid":"38123539","id":"PMC_38123539","title":"Mtfp1 ablation enhances mitochondrial respiration and protects against hepatic steatosis.","date":"2023","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/38123539","citation_count":27,"is_preprint":false},{"pmid":"28915614","id":"PMC_28915614","title":"Mitochondrial protein 18 (MTP18) plays a pro-apoptotic role in chemotherapy-induced gastric cancer cell apoptosis.","date":"2017","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/28915614","citation_count":22,"is_preprint":false},{"pmid":"23152874","id":"PMC_23152874","title":"Fluorescence lifetime readouts of Troponin-C-based calcium FRET sensors: a quantitative comparison of CFP and mTFP1 as donor fluorophores.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23152874","citation_count":21,"is_preprint":false},{"pmid":"35985563","id":"PMC_35985563","title":"MTP18 inhibition triggers mitochondrial hyperfusion to induce apoptosis through ROS-mediated lysosomal membrane permeabilization-dependent pathway in oral cancer.","date":"2022","source":"Free radical biology & medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35985563","citation_count":20,"is_preprint":false},{"pmid":"31337818","id":"PMC_31337818","title":"MTP18 is a Novel Regulator of Mitochondrial Fission in CNS Neuron Development, Axonal Growth, and Injury Responses.","date":"2019","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/31337818","citation_count":20,"is_preprint":false},{"pmid":"37313742","id":"PMC_37313742","title":"The inner mitochondrial membrane fission protein MTP18 serves as a mitophagy receptor to prevent apoptosis in oral cancer.","date":"2023","source":"Journal 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Cytometry","date":"2024-10-24","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.23.619855","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":19575,"output_tokens":5546,"usd":0.070958,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14075,"output_tokens":4104,"usd":0.086487,"stage2_stop_reason":"end_turn"},"total_usd":0.157445,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2004,\n      \"finding\": \"MTFP1 (MTP18) was identified as a nuclear-encoded mitochondrial protein whose mRNA and protein expression is dependent on PI 3-kinase activity. Knockdown via antisense molecules caused cytochrome c release and apoptosis, and reduced MTP18 levels resulted in a highly interconnected mitochondrial reticulum, while overexpression induced punctate mitochondrial morphology, establishing MTP18 as a downstream target of PI3K signaling that controls mitochondrial morphology and cell viability.\",\n      \"method\": \"Antisense knockdown, confocal microscopy, biochemical fractionation, overexpression studies in PC-3, HaCaT, and COS-7 cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (knockdown, overexpression, fractionation, cytochrome c release assay) in single lab\",\n      \"pmids\": [\"15155745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MTP18 functions as an essential intramitochondrial component of the mitochondrial division apparatus: overexpression induced mitochondrial fragmentation that was blocked by co-expression of Mfn1 or dominant-negative Drp1(K38A), RNAi-mediated knockdown produced highly fused mitochondria, and MTP18 knockdown blocked fission induced by hFis1 overexpression, placing MTP18 downstream of or parallel to hFis1 and requiring Drp1 for its fission activity.\",\n      \"method\": \"RNAi knockdown, overexpression, genetic epistasis with Mfn1, dominant-negative Drp1(K38A), and hFis1 co-expression; confocal microscopy of mitochondrial morphology\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal genetic epistasis with multiple fission/fusion proteins, replicated knockdown and overexpression, functionally validated pathway placement\",\n      \"pmids\": [\"15985469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"mTORC1 stimulates translation of MTFP1 via the eIF4E/4E-BP pathway to promote mitochondrial fission. MTFP1 expression is coupled to pro-fission phosphorylation and mitochondrial recruitment of DRP1. Active-site mTOR inhibitors reduce MTFP1 translation (mediated by 4E-BPs), causing mitochondrial hyperfusion; uncoupling MTFP1 levels from mTORC1/4E-BP upon mTOR inhibition blocks hyperfusion and converts mTOR inhibitor action from cytostatic to cytotoxic.\",\n      \"method\": \"Polysome profiling, mTOR inhibitor treatment, 4E-BP overexpression/knockdown, DRP1 phosphorylation and mitochondrial recruitment assays, cell viability and apoptosis readouts\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (translational control assays, epistasis with 4E-BPs, DRP1 recruitment, apoptosis), mechanistic pathway placement in single rigorous study\",\n      \"pmids\": [\"28918902\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MTFP1 knockdown prevents DRP1 (Dnm1l) accumulation at mitochondria and suppresses doxorubicin-induced mitochondrial fission and apoptosis in cardiac myocytes; conversely, MTFP1 overexpression sensitizes cells to doxorubicin-induced fission and apoptosis, establishing MTFP1 as a pro-fission effector acting upstream of DRP1 mitochondrial translocation.\",\n      \"method\": \"siRNA knockdown, overexpression, mitochondrial morphology imaging, apoptosis assays, DRP1 mitochondrial localization by fractionation/immunofluorescence in HL-1 cardiac myocytes\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockdown and overexpression with defined phenotypic readout and DRP1 localization, single lab\",\n      \"pmids\": [\"28643438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In gastric cancer cells, MTP18 overexpression enriches DRP1 accumulation at mitochondria and mediates doxorubicin-induced mitochondrial fission and apoptosis; MTP18 expression is downregulated during DOX treatment, suggesting its downregulation contributes to chemoresistance.\",\n      \"method\": \"Overexpression, mitochondrial fragmentation assay, DRP1 mitochondrial accumulation analysis, apoptosis assays in gastric cancer cells\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — overexpression and DRP1 localization, mechanistic follow-up, single lab with multiple readouts\",\n      \"pmids\": [\"28915614\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"miR-668 is induced in ischemic AKI via HIF-1 (a functional HIF-1 binding site was identified in the miR-668 promoter) and directly represses MTP18, as validated by luciferase reporter assay and RISC immunoprecipitation-RNA sequencing; MTP18 knockdown suppressed mitochondrial fragmentation and apoptosis in renal tubular cells, positioning MTP18 as a downstream effector of HIF-1/miR-668 in mitochondrial dynamics during ischemia.\",\n      \"method\": \"Anti-miR/mimic transfection, luciferase microRNA target reporter assay, RISC immunoprecipitation + RNA-seq, MTP18 knockdown, mitochondrial morphology and apoptosis assays, in vivo mouse AKI model\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (RISC-IP/RNA-seq, luciferase reporter, in vivo knockdown/mimic), replicated in cells and mice\",\n      \"pmids\": [\"30325740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In retinal ganglion cells (RGCs), MTP18/MTFP1 is critical for maintaining mitochondrial size and volume; MTP18 expression is regulated by KLF7 and KLF9 transcription factors, and MTP18 knockdown promotes axon growth, placing MTP18 as a downstream component of KLF-mediated axon regenerative signaling.\",\n      \"method\": \"siRNA knockdown, overexpression, mitochondrial morphology imaging, axon growth assays, transcription factor regulation analysis in RGCs\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockdown with defined phenotypic readouts and upstream TF identification, single lab\",\n      \"pmids\": [\"31337818\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In Xenopus tropicalis, the Mtfp1 gene is directly transcriptionally activated by thyroid hormone (T3) via thyroid hormone receptors (TRs) binding to a T3-response element (TRE) within the first intron, mediating local histone H3K79 methylation and RNA polymerase recruitment; Mtfp1 promoter activation by T3 was confirmed in a reconstituted frog oocyte system and found to require the intronic TRE.\",\n      \"method\": \"ChIP assay for TR binding and H3K79 methylation, RNA polymerase recruitment assay, reconstituted frog oocyte transcription assay, TRE deletion/mutation analysis\",\n      \"journal\": \"General and comparative endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — ChIP and reconstituted oocyte system with TRE validation, single lab, ortholog (Xenopus)\",\n      \"pmids\": [\"32827515\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"A small-molecule inhibitor (S28) of MTP18 induces stress-induced mitochondrial hyperfusion (SIMH) by inhibiting MTP18-mediated fission (decreased p-DRP1, increased Mfn1), leading to loss of mitochondrial membrane potential, mitochondrial superoxide generation, lysosomal membrane permeabilization (LMP), impaired autophagosome-lysosome fusion, and intrinsic apoptosis; MTP18 overexpression restored mitochondrial fission, induced mitophagy, and suppressed LMP and apoptosis.\",\n      \"method\": \"Small-molecule inhibition, overexpression, mitochondrial morphology imaging, p-DRP1 western blot, membrane potential assay, superoxide detection, lysosomal pH and LMP assays, apoptosis assays in oral cancer cells\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological inhibition plus overexpression with mechanistic pathway tracing, single lab\",\n      \"pmids\": [\"35985563\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"MTP18/MTFP1 functions as a mitophagy receptor: it contains an LC3-interacting region (LIR) that directly interacts with MAP1LC3 family members to target dysfunctional mitochondria to autophagosomes; LIR mutation (mLIR) abolishes this interaction and suppresses mitophagy; PINK1/Parkin deficiency abrogates MTP18-dependent mitophagy, and Parkin-mediated proteasomal degradation of the outer mitochondrial membrane is required for effective mitophagy downstream of MTP18.\",\n      \"method\": \"LIR motif mutation, co-immunoprecipitation of MTP18 with LC3 family members, PINK1/Parkin knockdown, CCCP-induced mitophagy assays, TOM20/COX IV degradation analysis, apoptosis assays in FaDu oral cancer cells\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — LIR mutagenesis combined with co-IP, epistasis with PINK1/Parkin, multiple orthogonal readouts of mitophagy\",\n      \"pmids\": [\"37313742\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Hepatocyte-specific deletion of Mtfp1 in mice is physiologically benign but leads to upregulation of oxidative phosphorylation (OXPHOS) activity and mitochondrial respiration independently of mitochondrial biogenesis, and protects against high-fat diet-induced steatosis. Additionally, Mtfp1 deletion inhibits mitochondrial permeability transition pore (mPTP) opening, conferring protection against apoptotic liver damage.\",\n      \"method\": \"Liver-specific Mtfp1 knockout mice, respirometry (Seahorse), proteomics, high-fat diet metabolic phenotyping, mPTP opening assay, ex vivo apoptosis assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional knockout with multiple orthogonal metabolic and functional assays in vivo and ex vivo, single rigorous study\",\n      \"pmids\": [\"38123539\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"MTFP1 is an inner mitochondrial membrane (IMM) protein that negatively regulates IMM fusion. Manipulation of MTFP1 levels modulates mtDNA copy number (CN). Mechanistically, MTFP1 inhibits mitochondrial fusion to isolate and exclude damaged IMM subdomains, which are then segregated by peripheral fission into small MTFP1-enriched mitochondria (SMEM) that are targeted for autophagic degradation; this MTFP1-dependent IMM quality control is essential for basal nucleoid recycling and maintaining adequate mtDNA levels.\",\n      \"method\": \"MTFP1 overexpression/knockout, mitochondrial fusion assays, super-resolution and live-cell imaging, mtDNA CN measurement, autophagy inhibition experiments, SMEM isolation and characterization\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods (live imaging, functional fusion assays, mtDNA CN quantification, autophagic pathway epistasis) in single rigorous study\",\n      \"pmids\": [\"38851188\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"HIF1A directly binds the MTFP1 promoter (validated by ChIP assay) and upregulates MTFP1 expression; MTFP1 overexpression promotes lung squamous cell carcinoma cell proliferation and metastasis by activating the glycolytic pathway.\",\n      \"method\": \"ChIP assay, western blot, cell proliferation/colony formation/migration assays, glycolysis pathway analysis in LUSC cells\",\n      \"journal\": \"Heliyon\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP confirmation of HIF1A binding plus functional cell assays, single lab\",\n      \"pmids\": [\"38689964\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PPA2 (inorganic pyrophosphatase, matrix-localized) directly interacts with MTFP1 and activates mitochondrial fission signaling by upregulating phosphorylated DNM1L S616 and its mitochondrial translocation; MTFP1 knockdown in PPA2-overexpressing cells abolishes DNM1L activation and fission. PPA2 utilizes the C-terminal LIR of MTFP1 for mitophagy-mediated clearance of damaged mitochondria, and PPA2 directs midzone fission (via MFF-DNM1L) for mitochondrial proliferation or peripheral fission (via FIS1-DNM1L) for mitophagy under stress.\",\n      \"method\": \"Co-immunoprecipitation of PPA2 with MTFP1, MTFP1 siRNA knockdown epistasis, overexpression studies, mitochondrial morphology imaging, DNM1L phosphorylation assays, CCCP-induced mitophagy assays, LIR mutation analysis\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus epistasis knockdown, multiple fission site readouts, single lab\",\n      \"pmids\": [\"40873007\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In zebrafish, the transcription factor Zbtb48 positively regulates Mtfp1 expression; zbtb48 knockout resulted in downregulation of mtfp1 at both mRNA and protein levels, particularly in ovary and testis, suggesting mtfp1 is an evolutionarily conserved transcriptional target of Zbtb48.\",\n      \"method\": \"CRISPR-Cas9 zbtb48 knockout zebrafish, RT-qPCR, western blot for Mtfp1 protein levels in gonads\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout with mRNA and protein validation, single lab, ortholog (zebrafish)\",\n      \"pmids\": [\"39987415\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In C. elegans, loss of mtp-18 increases longevity and stress resistance; mtp-18-mediated longevity requires the Forkhead transcription factor DAF-16 but is not mediated through the canonical IIS (insulin/IGF-1 signaling) cascade; MTP-18 shows unique genetic interactions with components of the mitochondrial electron transport chain, specifically coenzyme Q and cytochrome c mobile electron carrier system.\",\n      \"method\": \"mtp-18 loss-of-function mutants, lifespan assays, epistasis with daf-16 and IIS pathway mutants, genetic interaction with ETC component genes in C. elegans\",\n      \"journal\": \"Biogerontology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis in C. elegans with multiple pathway components, single lab, ortholog\",\n      \"pmids\": [\"41832346\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MTFP1 acts as a novel ATP synthase modulator through its interaction with multiple ATP synthase subunits (identified by GST pull-down), thereby enhancing oxidative phosphorylation; increased mitochondrial fission and ROS production downstream of MTFP1 upregulates SLC1A5 expression via the PI3K/AKT/c-MYC pathway, promoting glutamine uptake and impairing CD8+ T cell antitumor responses in pancreatic cancer liver metastasis.\",\n      \"method\": \"CRISPR loss-of-function screen, GST pull-down assay for ATP synthase subunit interaction, metabolic flux analysis, single-cell RNA-seq, spatial metabolomics, in vivo mouse models, PDAC organoids\",\n      \"journal\": \"Gut\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — GST pull-down for ATP synthase interaction plus functional metabolic assays and in vivo models, single lab\",\n      \"pmids\": [\"41663153\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MISO (Mitochondrial Inner membrane Subdomain Organizer) is required for SMEM formation; SMEM functionality requires MISO-dependent recruitment of MTFP1 and subsequent engagement of the FIS1-DRP1 fission machinery; MISO knockout completely abolishes SMEM generation, establishing MTFP1 as a downstream effector recruited by MISO to form SMEM and mediate peripheral fission and lysosomal mtDNA degradation.\",\n      \"method\": \"MISO knockout (Drosophila and mammalian cells), live-cell imaging of SMEM, MTFP1 localization assays, FIS1/DRP1 epistasis, lysosomal mtDNA degradation assays\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout with live imaging and pathway epistasis, preprint not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.01.05.631328\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"MTFP1 is essential for normal glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells; β-cell-specific MTFP1 knockout mice develop glucose intolerance, with sharply reduced oxidative phosphorylation and ATP production, disrupted mitochondrial cristae structure, and reduced ER-mitochondria contact surface. MTFP1 overexpression in mouse and human islets improved mitochondrial respiration and GSIS. MTFP1 was identified as a downstream effector of miR-125b: MTFP1 downregulation blocked the positive effects of miR-125b elimination on GSIS and mitochondrial respiration.\",\n      \"method\": \"β-cell-specific conditional knockout mice, glucose tolerance tests, respirometry, cristae ultrastructure (EM), ER-mitochondria contact quantification, MTFP1 overexpression in human islets, miR-125b epistasis experiments\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockout with multiple orthogonal functional assays and overexpression rescue, preprint not yet peer-reviewed\",\n      \"pmids\": [\"41648185\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"MTFP1 (MTP18) is an inner mitochondrial membrane protein that promotes mitochondrial fission by stimulating pro-fission phosphorylation and mitochondrial recruitment of DRP1; its expression is translationally controlled by the mTORC1/4E-BP/eIF4E axis and transcriptionally by HIF-1α and ZBTB48; it also functions as a mitophagy receptor via an LIR motif that engages LC3/MAP1LC3 family members in a PINK1/Parkin-dependent manner, and it negatively regulates IMM fusion to isolate damaged membrane subdomains into small MTFP1-enriched mitochondria (SMEM) for autophagic degradation, thereby controlling mtDNA copy number, OXPHOS activity, and cell fate decisions including apoptosis and insulin secretion.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MTFP1 (MTP18) is a nuclear-encoded inner mitochondrial membrane protein that promotes mitochondrial fission and governs mitochondrial morphology, quality control, and cell fate [#0, #1, #11]. Functionally it acts upstream of DRP1, driving pro-fission phosphorylation (p-DRP1 S616) and mitochondrial recruitment of DRP1; overexpression fragments the network while knockdown produces a hyperfused reticulum, and its fission activity is genetically dependent on DRP1 and antagonized by Mfn1 [#1, #2]. MTFP1 also enforces inner-membrane quality control: it negatively regulates IMM fusion to isolate damaged subdomains, which are segregated by peripheral fission into small MTFP1-enriched mitochondria (SMEM) and degraded by autophagy, a process required for nucleoid recycling and maintenance of mtDNA copy number [#11]. MTFP1 doubles as a mitophagy receptor through an LC3-interacting region (LIR) that binds MAP1LC3 family members to deliver dysfunctional mitochondria to autophagosomes in a PINK1/Parkin-dependent manner [#9]. MTFP1 abundance is set by multiple inputs: translationally by the mTORC1/4E-BP/eIF4E axis [#2] and transcriptionally by HIF-1\\u03b1 [#12] and the conserved factor ZBTB48 [#14]. Through these activities MTFP1 modulates OXPHOS and apoptosis: loss de-represses respiration, blocks mPTP opening, and protects against steatosis and apoptotic damage [#10], and it is required for glucose-stimulated insulin secretion in \\u03b2-cells [#18]. MTFP1 interacts with ATP synthase subunits and with PPA2, links to fission-driven metabolic reprogramming in cancer, and is recruited to nascent SMEM by MISO [#13, #16, #17].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Established MTP18 as a PI3K-dependent mitochondrial protein controlling network morphology and viability, framing it as a signaling-responsive regulator rather than a structural curiosity.\",\n      \"evidence\": \"Antisense knockdown, overexpression, fractionation, and cytochrome c release in PC-3/HaCaT/COS-7 cells\",\n      \"pmids\": [\"15155745\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not define molecular activity or partners\", \"Mechanism linking PI3K to morphology unresolved\", \"Single-lab phenotype\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Placed MTP18 in the fission machinery by showing its activity requires DRP1 and is antagonized by Mfn1/fusion, answering whether it acts in division versus fusion.\",\n      \"evidence\": \"RNAi, overexpression, and genetic epistasis with Mfn1, dominant-negative Drp1(K38A), and hFis1 by confocal imaging\",\n      \"pmids\": [\"15985469\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish direct biochemical interaction with DRP1\", \"Exact ordering relative to hFis1 ambiguous\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined how MTFP1 levels are set and translated that control into fission, showing mTORC1/4E-BP-driven translation couples MTFP1 abundance to DRP1 recruitment and cell fate.\",\n      \"evidence\": \"Polysome profiling, mTOR inhibition, 4E-BP manipulation, DRP1 phosphorylation/recruitment, and apoptosis assays\",\n      \"pmids\": [\"28918902\", \"28643438\", \"28915614\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MTFP1 directly modifies DRP1 not shown\", \"Tissue-specific relevance of translational control untested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified transcriptional/post-transcriptional repression of MTP18 by HIF-1/miR-668, showing MTFP1 is a tunable effector of ischemic mitochondrial dynamics.\",\n      \"evidence\": \"RISC-IP/RNA-seq, luciferase reporter, and in vivo knockdown/mimic in a mouse AKI model\",\n      \"pmids\": [\"30325740\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not address direct fission machinery interactions\", \"Generalizability beyond renal ischemia unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed MTP18 maintains mitochondrial size and is set by KLF transcription factors, linking its dosage to neuronal axon growth.\",\n      \"evidence\": \"siRNA, overexpression, mitochondrial imaging, and axon growth assays in retinal ganglion cells\",\n      \"pmids\": [\"31337818\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism connecting size control to axon growth unresolved\", \"Single-lab observation\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Demonstrated direct thyroid-hormone-receptor transcriptional activation of Mtfp1 via an intronic TRE, adding hormonal control to its regulatory repertoire.\",\n      \"evidence\": \"ChIP for TR binding and H3K79 methylation, RNA Pol recruitment, and reconstituted frog oocyte assay with TRE mutation\",\n      \"pmids\": [\"32827515\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Xenopus ortholog; human conservation not tested here\", \"Downstream physiological output not measured\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Used pharmacological inhibition to show MTP18-mediated fission gates a stress axis spanning hyperfusion, lysosomal permeabilization, and apoptosis.\",\n      \"evidence\": \"Small-molecule (S28) inhibition plus overexpression with membrane potential, superoxide, LMP, and apoptosis readouts in oral cancer cells\",\n      \"pmids\": [\"35985563\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Inhibitor specificity for MTP18 not fully validated\", \"Direct molecular target engagement unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Revealed a second function for MTFP1 as a mitophagy receptor, showing an LIR motif directly engages LC3 to deliver mitochondria to autophagosomes downstream of PINK1/Parkin.\",\n      \"evidence\": \"LIR mutagenesis, co-IP with LC3 family members, PINK1/Parkin knockdown, CCCP mitophagy and OMM degradation assays\",\n      \"pmids\": [\"37313742\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of LIR engagement not solved\", \"Coordination of fission vs receptor roles unresolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined the in vivo metabolic consequence of MTFP1 loss, showing it restrains OXPHOS and mPTP opening, linking fission control to steatosis and apoptotic protection.\",\n      \"evidence\": \"Liver-specific knockout mice with respirometry, proteomics, high-fat diet phenotyping, and mPTP assays\",\n      \"pmids\": [\"38123539\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which MTFP1 suppresses OXPHOS not defined\", \"Direct mPTP component interaction unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Established MTFP1 as an inner-membrane quality-control factor that segregates damaged subdomains into SMEM for autophagic mtDNA recycling, unifying its fission and degradation roles.\",\n      \"evidence\": \"Overexpression/knockout, fusion assays, super-resolution/live imaging, mtDNA copy-number quantification, and autophagy inhibition\",\n      \"pmids\": [\"38851188\", \"38689964\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How MTFP1 selectively recognizes damaged IMM unresolved\", \"Link between SMEM and mtDNA recycling mechanistically incomplete\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified direct protein partners (PPA2, ATP synthase subunits) and conserved regulators (ZBTB48), connecting MTFP1 to fission-site selection, OXPHOS modulation, and cancer/longevity phenotypes.\",\n      \"evidence\": \"Co-IP and GST pull-downs, siRNA epistasis, metabolic flux, in vivo cancer models, and ortholog knockouts in zebrafish and C. elegans\",\n      \"pmids\": [\"40873007\", \"41663153\", \"39987415\", \"41832346\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding interfaces not mapped\", \"Whether ATP synthase modulation is direct or fission-dependent unclear\", \"Ortholog phenotypes' human relevance untested\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Extended MTFP1's physiological role to \\u03b2-cell insulin secretion and to MISO-dependent SMEM assembly, defining recruitment hierarchy and a metabolic-endocrine function (preprints).\",\n      \"evidence\": \"\\u03b2-cell conditional knockout, respirometry, EM cristae/ER-mito contacts, miR-125b epistasis; MISO knockout with live imaging and FIS1/DRP1 epistasis (preprints)\",\n      \"pmids\": [\"41648185\", \"bio_10.1101_2025.01.05.631328\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprints not peer-reviewed\", \"Molecular nature of MISO\\u2013MTFP1 recruitment undefined\", \"How cristae/ER-mito defects arise from MTFP1 loss unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single IMM protein mechanistically toggles between promoting fission, restraining fusion, and acting as a mitophagy receptor, and the structural basis of its DRP1/LC3/PPA2/ATP-synthase interactions, remain open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of MTFP1 or its complexes\", \"Direct enzymatic/biochemical activity undefined\", \"Regulatory switch between fission and receptor modes unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2, 3]},\n      {\"term_id\": \"GO:0140097\", \"supporting_discovery_ids\": [11]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 16]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0, 11]},\n      {\"term_id\": \"GO:0005743\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [1, 11]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [9, 11]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [0, 10]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [10, 16]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"DNM1L\", \"MAP1LC3\", \"PPA2\", \"MISO\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}