{"gene":"IMMP2L","run_date":"2026-06-10T01:55:23","timeline":{"discoveries":[{"year":2001,"finding":"IMMP2L encodes the human homologue of yeast mitochondrial inner membrane peptidase subunit 2; the gene spans 860 kb, encompasses six exons, and produces a 1,522-bp transcript. It was identified as a novel gene disrupted by chromosomal breakpoints at 7q31 in a Tourette syndrome patient.","method":"cDNA cloning, Southern blot hybridization, FISH analysis","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cDNA cloning and genomic mapping established gene structure; single lab but multiple orthogonal molecular methods","pmids":["11254443"],"is_preprint":false},{"year":2007,"finding":"IMMP2L (Immp2l) is required for signal peptide processing of mitochondrial proteins cytochrome c1 (CYC1) and glycerol-3-phosphate dehydrogenase 2 (GPD2). Mutation of Immp2l impairs this processing, causing mitochondrial hyperpolarization, elevated superoxide generation, and higher ATP levels, leading to reproductive defects linked to decreased nitric oxide bioavailability and increased ROS.","method":"Transgenic insertional mutagenesis (Immp2lTg(Tyr)979Ove mouse), mitochondrial functional assays (membrane potential, superoxide measurement, ATP levels), protein processing analysis","journal":"Biology of reproduction","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo loss-of-function mouse model with multiple orthogonal biochemical readouts; replicated in subsequent studies","pmids":["18094351"],"is_preprint":false},{"year":2011,"finding":"Immp2l mutation impairs processing of CYC1 and GPD2 signal peptides, elevates mitochondrial superoxide in multiple organs, and causes accelerated aging phenotypes (sarcopenia, kyphosis, ataxia, loss of subcutaneous fat). Adipose-derived stromal cells from mutants show impaired proliferation and increased oxidative stress, linking mitochondrial ROS to adult stem cell dysfunction and age-associated disorders.","method":"Immp2l mutant mouse model, oxidative stress measurements (superoxide dismutase expression, protein carbonylation), colony formation assay, adipogenic differentiation assay","journal":"Aging cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — defined genetic mouse model with multiple orthogonal phenotypic and biochemical readouts; mechanistic follow-up of previously established substrate-processing role","pmids":["21332923"],"is_preprint":false},{"year":2012,"finding":"Immp2l mutation impairs processing of CYC1 and GPD2 signal peptides, generating elevated mitochondrial superoxide that causes age-dependent spermatogenic damage. Protein carbonyl content is elevated only in old (13-month) mutant testes coincident with spermatogenic failure; mtDNA mutation rate is unchanged, excluding a major role for mtDNA mutation in this ROS-mediated damage.","method":"Immp2l mutant mouse model, protein carbonyl assay, TUNEL apoptosis assay, mtDNA mutation rate analysis, antioxidant enzyme expression analysis","journal":"Free radical biology & medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — defined genetic model with multiple biochemical readouts; negative mtDNA mutation result mechanistically informative; consistent with replicated findings","pmids":["22569411"],"is_preprint":false},{"year":2014,"finding":"Despite impaired signal peptide cleavage of CYC1 and GPD2, the intermediate (unprocessed) forms of these proteins retain normal expression levels and enzymatic function in Immp2l mutant mice. Mitochondrial respiration is not diminished in isolated mitochondria or cells from mutant mice, indicating that respiratory deficiency is NOT the cause of Immp2l mutant phenotypes.","method":"Immp2l mutant mouse model, enzymatic activity assays for GPD2 and CYC1, mitochondrial respiration measurement (Seahorse or equivalent), protein expression analysis","journal":"Redox biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biochemical assays in a defined genetic model; single lab reporting a negative result that is mechanistically informative","pmids":["25460737"],"is_preprint":false},{"year":2015,"finding":"Immp2l mutation causes age-dependent degeneration specifically of cerebellar granule neurons (not Purkinje cells or molecular layer cells) in old mice (>16 months), accompanied by increased oxidative stress markers (HNE, nitrotyrosine, protein carbonyl). Treatment with the mitochondria-targeted antioxidant SkQ1 from 6 weeks to 21 months prevented granule neuron loss and restored SOD2 and VDAC1 expression, demonstrating a causal role for mitochondrial oxidative stress in this neurodegeneration.","method":"Immp2l mutant mouse model, histology/immunohistochemistry, SkQ1 antioxidant treatment, immunofluorescence for SOD2 and VDAC1, oxidative stress marker quantification","journal":"Aging cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic model plus pharmacological rescue experiment with multiple orthogonal readouts; demonstrates causal role of ROS in IMMP2L-dependent neurodegeneration","pmids":["26616244"],"is_preprint":false},{"year":2016,"finding":"IMMP2L transcription in human primary astrocytes requires Topoisomerase I. IMMP2L knockdown dysregulates genes involved in CNS development, and the transcriptional response partially overlaps with that induced by mitochondrial complex III inhibition.","method":"IMMP2L knockdown in human primary astrocytes, Topoisomerase I inhibition, transcriptome analysis (RNA-seq or microarray)","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — functional knockdown with transcriptomic readout in primary human cells; single lab, two methods (KD and TopoI inhibition comparison)","pmids":["27932244"],"is_preprint":false},{"year":2018,"finding":"IMMP2L processes and activates at least two substrates: mitochondrial metabolic enzyme GPD2 and cell death regulator apoptosis-inducing factor (AIF). Shutdown of IMMP2L-GPD2 signaling reprograms mitochondria-associated redox status and phospholipid metabolism, while shutdown of IMMP2L-AIF signaling blocks cell death under oxidative stress. Coordinated loss of both axes drives the cellular senescence program.","method":"Multi-omics approaches, IMMP2L knockdown/knockout cell models, metabolic profiling, senescence assays, identification of GPD2 and AIF as substrates","journal":"Cell research","confidence":"High","confidence_rationale":"Tier 2 / Strong — multi-omics approach with defined substrate identification (GPD2 and AIF), mechanistic dissection of two signaling axes, and in vivo aging validation; multiple orthogonal methods in one study","pmids":["29808012"],"is_preprint":false},{"year":2020,"finding":"In Immp2l-/- mice, follicle development is arrested at the secondary follicle stage due to mitochondrial dysfunction. The mechanism involves increased ROS, decreased estrogen levels, and altered Wnt/β-catenin and steroid hormone synthesis (CYP19A1) pathway gene expression. In vitro Immp2l knockdown in granulosa cells suppresses Wnt16, increases β-catenin, and decreases CYP19A1/estrogen, confirming the ROS-Wnt/β-catenin-estrogen pathway axis. Melatonin (antioxidant) treatment reverses these effects.","method":"Immp2l-/- mouse model, in vitro granulosa cell Immp2l knockdown, ROS measurement, hormone assays, Western blot/gene expression for Wnt pathway components, melatonin rescue experiment","journal":"Endocrinology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO plus in vitro KD with pharmacological rescue; multiple orthogonal biochemical and cellular readouts establishing pathway","pmids":["32652035"],"is_preprint":false},{"year":2023,"finding":"IMMP2L/Immp2l cleaves the mitochondrial transit peptide from GPD2 (and CYC1), and this processing enhances GPD2 homodimeric structure and its respiratory function. In Immp2l-/- KO mice, glycerol-3-phosphate (G3P)-driven mitochondrial respiration is decreased (~20% female, ~7% male), nonmitochondrial respiration is dramatically lowered, AlphaFold2-Multimer structural modeling predicts altered Cyc1-cytochrome b interaction in Complex III and disrupted GPD2 homodimer structure. Primary MEF cells show ~27% decrease in total respiration and ~50% decrease in nonmitochondrial respiration.","method":"Immp2l-/- KO mouse model, substrate-specific mitochondrial respiration assays (G3P, succinate, glutamate), AlphaFold2-Multimer structural prediction, EchoMRI, mitoROS measurement, primary MEF cell lines","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with substrate-specific functional respiration assays; structural prediction is computational (Tier 4) but functional data is Tier 2; single lab","pmids":["38256063"],"is_preprint":false},{"year":2023,"finding":"In Immp2l-/- KO mice (complete knockout devoid of peptidase activity), ROS levels are significantly LOWERED (not elevated), and mice are fully fertile with no age-related ataxia or neurodegeneration. This contrasts with the elevated ROS phenotype of the earlier truncated Immp2l mutant (intragenic deletion) mouse model, suggesting that oxidative stress phenotypes previously attributed to IMMP2L loss may be specific to the truncated protein rather than complete absence of peptidase activity.","method":"Immp2l-/- KO mouse model, mitoROS measurement, fertility assessment, electron microscopy for neurodegeneration, MitoQ antioxidant treatment","journal":"Genes","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — complete KO mouse with multiple orthogonal readouts; a negative result (no elevated ROS) mechanistically informative and contradicts earlier studies; single lab","pmids":["37761857"],"is_preprint":false},{"year":2024,"finding":"In Immp2l-knockout granulosa cells, STAT1 expression is increased and controlled by S-glutathionylation and S-nitrosylation (not phosphorylation), as shown by Co-IP. Immp2l deficiency impairs UPRmt (unfolded protein response of mitochondria) and activates HIF1α/BNIP3-mediated mitophagy, but mitophagy is blocked due to reduced fusion of mitophagosomes and lysosomes, leading to mitochondria accumulation, increased ROS, and granulosa cell senescence.","method":"Immp2l knockout mouse/cell model, Co-IP for STAT1 modifications, Western blot for UPRmt and mitophagy pathway components, mitochondrial function assays, senescence assays, enocyanin treatment rescue","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and multiple pathway analyses in KO cells with pharmacological rescue; single lab, mechanistic pathway dissection","pmids":["39456903"],"is_preprint":false},{"year":2025,"finding":"Immp2l knockout induces mtDNA leakage from mitochondria into the cytoplasm via CyPD40 (inner membrane pore) and VDAC1 (outer membrane pore), both of which are upregulated. Cytoplasmic mtDNA activates cGAS-STING signaling and downstream interferon-stimulated genes, promoting SASP (senescence-associated secretory phenotype) and granulosa cell senescence. TFAM knockdown (siRNA) reduces cytoplasmic mtDNA and inhibits cGAS-STING activation, confirming TFAM-mediated mtDNA stability as a key regulatory node.","method":"Immp2l KO mouse/granulosa cell model, siRNA knockdown of TFAM, Western blot for cGAS-STING pathway components and CyPD40/VDAC1, cytoplasmic mtDNA measurement, SASP assays, PCB2 treatment rescue","journal":"International journal of biological macromolecules","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO plus siRNA epistasis experiment with multiple pathway readouts; single lab, establishes mechanistic link between IMMP2L loss and innate immune activation via mtDNA leakage","pmids":["40120895"],"is_preprint":false},{"year":2023,"finding":"Immp2l+/- (heterozygous) mutation leads to mitochondrial membrane potential depolarization and suppression of mitochondrial respiratory Complex III activity after cerebral ischemia-reperfusion injury. This is accompanied by caspase-3 activation and AIF nuclear translocation, indicating activation of mitochondria-mediated apoptosis pathways.","method":"Immp2l+/- mouse model, middle cerebral artery occlusion (MCAO) ischemia-reperfusion model, JC-1 mitochondrial membrane potential assay, Complex III activity assay, caspase-3 Western blot, AIF nuclear translocation assay","journal":"Current medical science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — defined genetic model with multiple biochemical readouts in a disease context; single lab, multiple orthogonal methods","pmids":["37243806"],"is_preprint":false}],"current_model":"IMMP2L encodes a mitochondrial inner membrane peptidase that cleaves the signal/transit peptides from nuclear-encoded mitochondrial proteins cytochrome c1 (CYC1) and glycerol-3-phosphate dehydrogenase 2 (GPD2), thereby enhancing GPD2 homodimeric structure, Gpd2-driven mitochondrial respiration, and CYC1/Complex III function; loss of IMMP2L activity impairs this processing and coordinately shuts down IMMP2L-GPD2 metabolic signaling and IMMP2L-AIF cell death signaling, reprogramming mitochondrial redox and phospholipid metabolism to drive cellular senescence, while also causing mtDNA leakage through CyPD40/VDAC1 pores that activates cGAS-STING innate immune signaling and SASP, and in vivo mutation leads to elevated superoxide, age-dependent reproductive failure, neurodegeneration, and accelerated aging phenotypes that are partially rescuable by mitochondria-targeted antioxidants."},"narrative":{"mechanistic_narrative":"IMMP2L encodes the human homologue of the yeast mitochondrial inner membrane peptidase subunit 2, a gene first identified through chromosomal breakpoints at 7q31 in a Tourette syndrome patient [PMID:11254443]. Its core molecular function is proteolytic cleavage of the signal/transit peptides from nuclear-encoded mitochondrial proteins, with cytochrome c1 (CYC1) and glycerol-3-phosphate dehydrogenase 2 (GPD2) established as substrates [PMID:18094351, PMID:38256063]. This processing matures GPD2 into its homodimeric, respiration-competent form and supports CYC1 function within Complex III, such that loss of IMMP2L lowers glycerol-3-phosphate-driven and nonmitochondrial respiration [PMID:38256063]. Beyond metabolic enzymes, IMMP2L also processes apoptosis-inducing factor (AIF), and coordinated shutdown of the IMMP2L–GPD2 (redox/phospholipid) and IMMP2L–AIF (cell death) axes drives a cellular senescence program [PMID:29808012]. In vivo, IMMP2L deficiency converges on mitochondrial dysfunction with downstream consequences including age-dependent reproductive failure, cerebellar granule neuron degeneration, and accelerated aging phenotypes, several of which are rescuable by mitochondria-targeted antioxidants [PMID:21332923, PMID:26616244, PMID:32652035]. In granulosa cells, IMMP2L loss causes mtDNA leakage through CyPD40/VDAC1 pores that activates cGAS-STING innate immune signaling and the SASP [PMID:40120895]. The redox direction of IMMP2L loss is allele-dependent: an intragenic-deletion (truncated) mutant elevates mitochondrial superoxide [PMID:18094351, PMID:21332923, PMID:22569411], whereas a complete knockout lowers ROS and shows preserved fertility and no neurodegeneration [PMID:37761857], indicating that some oxidative-stress phenotypes are specific to the truncated protein rather than absence of peptidase activity.","teleology":[{"year":2001,"claim":"Established the existence and genomic structure of human IMMP2L and a first disease association, framing it as a candidate mitochondrial peptidase subunit disrupted at 7q31.","evidence":"cDNA cloning, Southern blot, and FISH mapping in a Tourette syndrome patient","pmids":["11254443"],"confidence":"Medium","gaps":["No biochemical demonstration of peptidase activity","Causal link to Tourette syndrome not established beyond breakpoint mapping"]},{"year":2007,"claim":"Defined IMMP2L's molecular substrates by showing it is required for signal-peptide processing of CYC1 and GPD2, connecting loss of processing to mitochondrial hyperpolarization, elevated superoxide, and reproductive defects.","evidence":"Transgenic insertional Immp2l mutant mouse with membrane potential, superoxide, ATP, and protein-processing assays","pmids":["18094351"],"confidence":"High","gaps":["Did not resolve whether ROS arises from the truncated protein or loss of activity per se","Direct enzymatic cleavage in vitro not reconstituted"]},{"year":2011,"claim":"Extended the processing defect to systemic consequences, linking IMMP2L-dependent mitochondrial ROS to adult stem cell dysfunction and accelerated aging phenotypes.","evidence":"Immp2l mutant mouse with oxidative-stress markers, colony formation, and adipogenic differentiation assays","pmids":["21332923"],"confidence":"High","gaps":["Mechanism connecting substrate misprocessing to ROS production not defined","Tissue specificity of phenotypes unexplained"]},{"year":2012,"claim":"Showed the ROS-mediated damage is age-dependent and not driven by mtDNA mutation, narrowing the mechanism to oxidative protein damage rather than genomic instability.","evidence":"Immp2l mutant mouse testis with protein carbonyl, TUNEL, and mtDNA mutation-rate assays","pmids":["22569411"],"confidence":"High","gaps":["Source of age-dependent onset unexplained","Did not test antioxidant rescue in this tissue"]},{"year":2014,"claim":"Complicated the respiratory-deficiency model by showing unprocessed CYC1/GPD2 retain enzymatic function and respiration is not diminished, arguing the phenotype is not a simple respiratory chain defect.","evidence":"Immp2l mutant mouse with enzyme activity and mitochondrial respiration measurements","pmids":["25460737"],"confidence":"Medium","gaps":["Negative result from a single lab","Apparent tension with later KO respiration data unresolved"]},{"year":2015,"claim":"Demonstrated causality of mitochondrial oxidative stress in IMMP2L-dependent neurodegeneration via pharmacological rescue, identifying cerebellar granule neurons as a selectively vulnerable cell type.","evidence":"Immp2l mutant mouse with histology and chronic SkQ1 mitochondria-targeted antioxidant treatment","pmids":["26616244"],"confidence":"High","gaps":["Basis of granule-neuron selectivity unknown","Molecular link from misprocessing to ROS not defined"]},{"year":2016,"claim":"Connected IMMP2L expression regulation to Topoisomerase I and showed its knockdown dysregulates CNS-development genes overlapping with Complex III inhibition, linking IMMP2L loss to a transcriptional program.","evidence":"IMMP2L knockdown and Topoisomerase I inhibition with transcriptome profiling in human primary astrocytes","pmids":["27932244"],"confidence":"Medium","gaps":["Directness of transcriptional effects not established","Mechanism of TopoI-dependent transcription unexplained"]},{"year":2018,"claim":"Identified AIF as a second IMMP2L substrate and partitioned IMMP2L function into a GPD2-linked redox/phospholipid axis and an AIF-linked cell-death axis whose coordinated loss executes senescence.","evidence":"Multi-omics, knockdown/knockout cell models, metabolic profiling, and senescence assays","pmids":["29808012"],"confidence":"High","gaps":["Direct cleavage of AIF by IMMP2L not biochemically reconstituted","How two axes are jointly sensed to trigger senescence unclear"]},{"year":2020,"claim":"Mapped a tissue-level mechanism in ovary, showing IMMP2L loss arrests follicle development through a ROS–Wnt/β-catenin–estrogen (CYP19A1) axis reversible by antioxidant treatment.","evidence":"Immp2l-/- mouse and granulosa cell knockdown with hormone assays, Wnt-pathway Western blots, and melatonin rescue","pmids":["32652035"],"confidence":"High","gaps":["Link between mitochondrial ROS and Wnt regulation not molecularly defined","Whether AIF or GPD2 axis dominates here untested"]},{"year":2023,"claim":"Quantified the respiratory consequence of complete knockout, showing reduced G3P-driven and nonmitochondrial respiration and predicting disrupted GPD2 homodimer and Cyc1–cytochrome b interaction, reaffirming a respiratory role for substrate processing.","evidence":"Immp2l-/- mice and MEFs with substrate-specific respiration assays and AlphaFold2-Multimer modeling","pmids":["38256063"],"confidence":"Medium","gaps":["Structural predictions are computational and unvalidated experimentally","Tension with the earlier no-respiratory-deficit report unresolved"]},{"year":2023,"claim":"Revealed that a complete knockout LOWERS ROS and preserves fertility and neurological health, indicating earlier oxidative phenotypes may be specific to the truncated allele rather than loss of peptidase activity.","evidence":"Immp2l-/- complete KO mouse with mitoROS, fertility, electron microscopy, and MitoQ treatment","pmids":["37761857"],"confidence":"Medium","gaps":["Mechanism by which the truncated protein gains a toxic ROS phenotype not defined","Single lab; reconciliation with allele-specific phenotypes incomplete"]},{"year":2023,"claim":"Showed IMMP2L dosage matters in acute injury, with heterozygous mutation suppressing Complex III activity and triggering caspase-3 and AIF nuclear translocation after cerebral ischemia-reperfusion.","evidence":"Immp2l+/- mice in an MCAO model with JC-1, Complex III activity, caspase-3, and AIF translocation assays","pmids":["37243806"],"confidence":"Medium","gaps":["Whether AIF translocation depends on IMMP2L processing of AIF not tested here","Heterozygous-specific mechanism not isolated"]},{"year":2024,"claim":"Connected IMMP2L loss to impaired mitochondrial quality control, showing blocked HIF1α/BNIP3 mitophagy, defective UPRmt, and redox-controlled STAT1 upregulation driving granulosa-cell senescence.","evidence":"Immp2l KO cells with Co-IP of STAT1 modifications, mitophagy/UPRmt Western blots, and enocyanin rescue","pmids":["39456903"],"confidence":"Medium","gaps":["STAT1 Co-IP modifications shown without reciprocal validation","Causal ordering of UPRmt failure vs mitophagy block unclear"]},{"year":2025,"claim":"Established a mechanistic link from IMMP2L loss to innate immune activation, showing mtDNA leaks through upregulated CyPD40/VDAC1 pores to activate cGAS-STING and SASP, with TFAM knockdown as an epistatic suppressor.","evidence":"Immp2l KO granulosa cells with TFAM siRNA epistasis, cGAS-STING/CyPD40/VDAC1 Western blots, cytoplasmic mtDNA quantification, and PCB2 rescue","pmids":["40120895"],"confidence":"Medium","gaps":["Direct mechanism of pore upregulation by IMMP2L loss unknown","Single lab; cell-type generality untested"]},{"year":null,"claim":"It remains unresolved how the truncated-allele toxic-gain phenotype mechanistically differs from complete loss of peptidase activity, and whether direct enzymatic cleavage of GPD2, CYC1, and AIF can be reconstituted in vitro.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No in vitro reconstitution of IMMP2L peptidase on defined substrates","Allele-dependent ROS direction not mechanistically explained","Direct AIF cleavage by IMMP2L not biochemically demonstrated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[1,7,9]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[1,9]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[1,9,12]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[7,9]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[1,9]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[12]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[7,13]}],"complexes":[],"partners":["GPD2","CYC1","AIF"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96T52","full_name":"Mitochondrial inner membrane protease subunit 2","aliases":["IMP2-like protein"],"length_aa":175,"mass_kda":19.7,"function":"Catalyzes the removal of transit peptides required for the targeting of proteins from the mitochondrial matrix, across the inner membrane, into the inter-membrane space. Known to process the nuclear encoded protein DIABLO","subcellular_location":"Mitochondrion inner membrane","url":"https://www.uniprot.org/uniprotkb/Q96T52/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/IMMP2L","classification":"Not Classified","n_dependent_lines":6,"n_total_lines":1208,"dependency_fraction":0.004966887417218543},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/IMMP2L","total_profiled":1310},"omim":[{"mim_id":"612323","title":"INNER MITOCHONDRIAL MEMBRANE PEPTIDASE, SUBUNIT 1; IMMP1L","url":"https://www.omim.org/entry/612323"},{"mim_id":"605977","title":"INNER MITOCHONDRIAL MEMBRANE PEPTIDASE, SUBUNIT 2; IMMP2L","url":"https://www.omim.org/entry/605977"},{"mim_id":"605219","title":"DIRECT IAP-BINDING PROTEIN WITH LOW pI; DIABLO","url":"https://www.omim.org/entry/605219"},{"mim_id":"137580","title":"GILLES DE LA TOURETTE SYNDROME; GTS","url":"https://www.omim.org/entry/137580"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Mitochondria","reliability":"Approved"},{"location":"Flagellar centriole","reliability":"Additional"},{"location":"Principal piece","reliability":"Additional"},{"location":"End piece","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/IMMP2L"},"hgnc":{"alias_symbol":["IMP2"],"prev_symbol":["IMMP2L-IT1"]},"alphafold":{"accession":"Q96T52","domains":[{"cath_id":"2.10.109.10","chopping":"35-157","consensus_level":"high","plddt":92.5874,"start":35,"end":157}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96T52","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96T52-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96T52-F1-predicted_aligned_error_v6.png","plddt_mean":87.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=IMMP2L","jax_strain_url":"https://www.jax.org/strain/search?query=IMMP2L"},"sequence":{"accession":"Q96T52","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96T52.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96T52/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96T52"}},"corpus_meta":[{"pmid":"11254443","id":"PMC_11254443","title":"Disruption of a novel gene (IMMP2L) by a breakpoint in 7q31 associated with Tourette syndrome.","date":"2001","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/11254443","citation_count":127,"is_preprint":false},{"pmid":"19401682","id":"PMC_19401682","title":"High-density SNP association study and copy number variation analysis of the AUTS1 and AUTS5 loci implicate the IMMP2L-DOCK4 gene region in autism susceptibility.","date":"2009","source":"Molecular psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/19401682","citation_count":112,"is_preprint":false},{"pmid":"18094351","id":"PMC_18094351","title":"A mutation in the inner mitochondrial membrane peptidase 2-like gene (Immp2l) affects mitochondrial function and impairs fertility in mice.","date":"2007","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/18094351","citation_count":87,"is_preprint":false},{"pmid":"21332923","id":"PMC_21332923","title":"Mitochondrial peptidase IMMP2L mutation causes early onset of age-associated disorders and impairs adult stem cell self-renewal.","date":"2011","source":"Aging cell","url":"https://pubmed.ncbi.nlm.nih.gov/21332923","citation_count":58,"is_preprint":false},{"pmid":"21386874","id":"PMC_21386874","title":"Translocation breakpoint at 7q31 associated with tics: further evidence for IMMP2L as a candidate gene for Tourette syndrome.","date":"2011","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/21386874","citation_count":56,"is_preprint":false},{"pmid":"24549057","id":"PMC_24549057","title":"Intragenic deletions affecting two alternative transcripts of the IMMP2L gene in patients with Tourette syndrome.","date":"2014","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/24549057","citation_count":55,"is_preprint":false},{"pmid":"29808012","id":"PMC_29808012","title":"Switching off IMMP2L signaling drives senescence via simultaneous metabolic alteration and blockage of cell death.","date":"2018","source":"Cell research","url":"https://pubmed.ncbi.nlm.nih.gov/29808012","citation_count":45,"is_preprint":false},{"pmid":"17043892","id":"PMC_17043892","title":"Molecular and genomic studies of IMMP2L and mutation screening in autism and Tourette syndrome.","date":"2006","source":"Molecular genetics and genomics : MGG","url":"https://pubmed.ncbi.nlm.nih.gov/17043892","citation_count":39,"is_preprint":false},{"pmid":"32652035","id":"PMC_32652035","title":"The Immp2l Mutation Causes Ovarian Aging Through ROS-Wnt/β-Catenin-Estrogen Pathway: Preventive Effect of Melatonin.","date":"2020","source":"Endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/32652035","citation_count":35,"is_preprint":false},{"pmid":"26616244","id":"PMC_26616244","title":"The Immp2l mutation causes age-dependent degeneration of cerebellar granule neurons prevented by antioxidant treatment.","date":"2015","source":"Aging cell","url":"https://pubmed.ncbi.nlm.nih.gov/26616244","citation_count":30,"is_preprint":false},{"pmid":"22569411","id":"PMC_22569411","title":"Oxidative stress is involved in age-dependent spermatogenic damage of Immp2l mutant mice.","date":"2012","source":"Free radical biology & medicine","url":"https://pubmed.ncbi.nlm.nih.gov/22569411","citation_count":29,"is_preprint":false},{"pmid":"24599690","id":"PMC_24599690","title":"Family-based association study of ZNF533, DOCK4 and IMMP2L gene polymorphisms linked to autism in a northeastern Chinese Han population.","date":"2014","source":"Journal of Zhejiang University. Science. B","url":"https://pubmed.ncbi.nlm.nih.gov/24599690","citation_count":28,"is_preprint":false},{"pmid":"25478008","id":"PMC_25478008","title":"Interstitial 7q31.1 copy number variations disrupting IMMP2L gene are associated with a wide spectrum of neurodevelopmental disorders.","date":"2014","source":"Molecular cytogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/25478008","citation_count":28,"is_preprint":false},{"pmid":"25460737","id":"PMC_25460737","title":"Examination of bioenergetic function in the inner mitochondrial membrane peptidase 2-like (Immp2l) mutant mice.","date":"2014","source":"Redox biology","url":"https://pubmed.ncbi.nlm.nih.gov/25460737","citation_count":21,"is_preprint":false},{"pmid":"31233820","id":"PMC_31233820","title":"First behavioural assessment of a novel Immp2l knockdown mouse model with relevance for Gilles de la Tourette syndrome and Autism spectrum disorder.","date":"2019","source":"Behavioural brain research","url":"https://pubmed.ncbi.nlm.nih.gov/31233820","citation_count":19,"is_preprint":false},{"pmid":"29152845","id":"PMC_29152845","title":"Association of IMMP2L deletions with autism spectrum disorder: A trio family study and meta-analysis.","date":"2017","source":"American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/29152845","citation_count":17,"is_preprint":false},{"pmid":"35095490","id":"PMC_35095490","title":"Guilingji Protects Against Spermatogenesis Dysfunction From Oxidative Stress via Regulation of MAPK and Apoptotic Signaling Pathways in Immp2l Mutant Mice.","date":"2022","source":"Frontiers in pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/35095490","citation_count":14,"is_preprint":false},{"pmid":"32922348","id":"PMC_32922348","title":"Association of Genetic Variation in the 3'UTR of LHX6, IMMP2L, and AADAC With Tourette Syndrome.","date":"2020","source":"Frontiers in neurology","url":"https://pubmed.ncbi.nlm.nih.gov/32922348","citation_count":13,"is_preprint":false},{"pmid":"32141651","id":"PMC_32141651","title":"Lycium barbarum polysaccharide protects against ethanol-induced spermiotoxicity and testicular degeneration in Immp2l+/- mice.","date":"2020","source":"Andrologia","url":"https://pubmed.ncbi.nlm.nih.gov/32141651","citation_count":12,"is_preprint":false},{"pmid":"27081546","id":"PMC_27081546","title":"A novel KCNQ4 mutation and a private IMMP2L-DOCK4 duplication segregating with nonsyndromic hearing loss in a Brazilian family.","date":"2015","source":"Human genome variation","url":"https://pubmed.ncbi.nlm.nih.gov/27081546","citation_count":12,"is_preprint":false},{"pmid":"33849037","id":"PMC_33849037","title":"Differential DNA Methylation of the IMMP2L Gene in Families with Maternally Inherited 7q31.1 Microdeletions is Associated with Intellectual Disability and Developmental Delay.","date":"2021","source":"Cytogenetic and genome research","url":"https://pubmed.ncbi.nlm.nih.gov/33849037","citation_count":10,"is_preprint":false},{"pmid":"28703400","id":"PMC_28703400","title":"Mitochondria-targeted antioxidant SkQ1 improves spermatogenesis in Immp2l mutant mice.","date":"2017","source":"Andrologia","url":"https://pubmed.ncbi.nlm.nih.gov/28703400","citation_count":10,"is_preprint":false},{"pmid":"37541448","id":"PMC_37541448","title":"Immp2l knockdown in male mice increases stimulus-driven instrumental behaviour but does not alter goal-directed learning or neuron density in cortico-striatal circuits in a model of Tourette syndrome and autism spectrum disorder.","date":"2023","source":"Behavioural brain research","url":"https://pubmed.ncbi.nlm.nih.gov/37541448","citation_count":9,"is_preprint":false},{"pmid":"28316022","id":"PMC_28316022","title":"Suppression of Inner Mitochondrial Membrane Peptidase 2-Like (IMMP2L) Gene Exacerbates Hypoxia-Induced Neural Death Under High Glucose Condition.","date":"2017","source":"Neurochemical research","url":"https://pubmed.ncbi.nlm.nih.gov/28316022","citation_count":9,"is_preprint":false},{"pmid":"27932244","id":"PMC_27932244","title":"Transcriptional response to mitochondrial protease IMMP2L knockdown in human primary astrocytes.","date":"2016","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/27932244","citation_count":9,"is_preprint":false},{"pmid":"29788020","id":"PMC_29788020","title":"Genomic Deletion Involving the IMMP2L Gene in Two Cases of Autism Spectrum Disorder.","date":"2018","source":"Cytogenetic and genome research","url":"https://pubmed.ncbi.nlm.nih.gov/29788020","citation_count":9,"is_preprint":false},{"pmid":"32265818","id":"PMC_32265818","title":"Mitochondrial Function in Gilles de la Tourette Syndrome Patients With and Without Intragenic IMMP2L Deletions.","date":"2020","source":"Frontiers in neurology","url":"https://pubmed.ncbi.nlm.nih.gov/32265818","citation_count":8,"is_preprint":false},{"pmid":"37761857","id":"PMC_37761857","title":"Antioxidant Behavioural Phenotype in the Immp2l Gene Knock-Out Mouse.","date":"2023","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/37761857","citation_count":7,"is_preprint":false},{"pmid":"39456903","id":"PMC_39456903","title":"Immp2l Deficiency Induced Granulosa Cell Senescence Through STAT1/ATF4 Mediated UPRmt and STAT1/(ATF4)/HIF1α/BNIP3 Mediated Mitophagy: Prevented by Enocyanin.","date":"2024","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/39456903","citation_count":7,"is_preprint":false},{"pmid":"40120895","id":"PMC_40120895","title":"Immp2l gene knockout induces granulosa cell senescence by activation of cGAS-STING pathway via TFAM-mediated mtDNA leakage.","date":"2025","source":"International journal of biological macromolecules","url":"https://pubmed.ncbi.nlm.nih.gov/40120895","citation_count":5,"is_preprint":false},{"pmid":"34914312","id":"PMC_34914312","title":"[Lycium barbarum polysaccharide reduces testicular spermatogenic injury in Immp2l－/－mice through GPX4 and AIF pathways].","date":"2021","source":"Zhonghua nan ke xue = National journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/34914312","citation_count":5,"is_preprint":false},{"pmid":"37243806","id":"PMC_37243806","title":"Immp2l Mutation Induces Mitochondrial Membrane Depolarization and Complex III Activity Suppression after Middle Cerebral Artery Occlusion in Mice.","date":"2023","source":"Current medical science","url":"https://pubmed.ncbi.nlm.nih.gov/37243806","citation_count":3,"is_preprint":false},{"pmid":"38256063","id":"PMC_38256063","title":"Immp2l Enhances the Structure and Function of Mitochondrial Gpd2 Dehydrogenase.","date":"2024","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/38256063","citation_count":2,"is_preprint":false},{"pmid":"34140073","id":"PMC_34140073","title":"[IMMP2L gene mutation activates mitochondrial apoptotic pathway to aggravate cerebral ischemic injury in mice].","date":"2021","source":"Xi bao yu fen zi mian yi xue za zhi = Chinese journal of cellular and molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/34140073","citation_count":2,"is_preprint":false},{"pmid":"29921919","id":"PMC_29921919","title":"Author Correction: IMMP2L: a mitochondrial protease suppressing cellular senescence.","date":"2018","source":"Cell research","url":"https://pubmed.ncbi.nlm.nih.gov/29921919","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":19421,"output_tokens":4163,"usd":0.060354,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12210,"output_tokens":4537,"usd":0.087237,"stage2_stop_reason":"end_turn"},"total_usd":0.147591,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2001,\n      \"finding\": \"IMMP2L encodes the human homologue of yeast mitochondrial inner membrane peptidase subunit 2; the gene spans 860 kb, encompasses six exons, and produces a 1,522-bp transcript. It was identified as a novel gene disrupted by chromosomal breakpoints at 7q31 in a Tourette syndrome patient.\",\n      \"method\": \"cDNA cloning, Southern blot hybridization, FISH analysis\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cDNA cloning and genomic mapping established gene structure; single lab but multiple orthogonal molecular methods\",\n      \"pmids\": [\"11254443\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"IMMP2L (Immp2l) is required for signal peptide processing of mitochondrial proteins cytochrome c1 (CYC1) and glycerol-3-phosphate dehydrogenase 2 (GPD2). Mutation of Immp2l impairs this processing, causing mitochondrial hyperpolarization, elevated superoxide generation, and higher ATP levels, leading to reproductive defects linked to decreased nitric oxide bioavailability and increased ROS.\",\n      \"method\": \"Transgenic insertional mutagenesis (Immp2lTg(Tyr)979Ove mouse), mitochondrial functional assays (membrane potential, superoxide measurement, ATP levels), protein processing analysis\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo loss-of-function mouse model with multiple orthogonal biochemical readouts; replicated in subsequent studies\",\n      \"pmids\": [\"18094351\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Immp2l mutation impairs processing of CYC1 and GPD2 signal peptides, elevates mitochondrial superoxide in multiple organs, and causes accelerated aging phenotypes (sarcopenia, kyphosis, ataxia, loss of subcutaneous fat). Adipose-derived stromal cells from mutants show impaired proliferation and increased oxidative stress, linking mitochondrial ROS to adult stem cell dysfunction and age-associated disorders.\",\n      \"method\": \"Immp2l mutant mouse model, oxidative stress measurements (superoxide dismutase expression, protein carbonylation), colony formation assay, adipogenic differentiation assay\",\n      \"journal\": \"Aging cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — defined genetic mouse model with multiple orthogonal phenotypic and biochemical readouts; mechanistic follow-up of previously established substrate-processing role\",\n      \"pmids\": [\"21332923\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Immp2l mutation impairs processing of CYC1 and GPD2 signal peptides, generating elevated mitochondrial superoxide that causes age-dependent spermatogenic damage. Protein carbonyl content is elevated only in old (13-month) mutant testes coincident with spermatogenic failure; mtDNA mutation rate is unchanged, excluding a major role for mtDNA mutation in this ROS-mediated damage.\",\n      \"method\": \"Immp2l mutant mouse model, protein carbonyl assay, TUNEL apoptosis assay, mtDNA mutation rate analysis, antioxidant enzyme expression analysis\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — defined genetic model with multiple biochemical readouts; negative mtDNA mutation result mechanistically informative; consistent with replicated findings\",\n      \"pmids\": [\"22569411\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Despite impaired signal peptide cleavage of CYC1 and GPD2, the intermediate (unprocessed) forms of these proteins retain normal expression levels and enzymatic function in Immp2l mutant mice. Mitochondrial respiration is not diminished in isolated mitochondria or cells from mutant mice, indicating that respiratory deficiency is NOT the cause of Immp2l mutant phenotypes.\",\n      \"method\": \"Immp2l mutant mouse model, enzymatic activity assays for GPD2 and CYC1, mitochondrial respiration measurement (Seahorse or equivalent), protein expression analysis\",\n      \"journal\": \"Redox biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biochemical assays in a defined genetic model; single lab reporting a negative result that is mechanistically informative\",\n      \"pmids\": [\"25460737\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Immp2l mutation causes age-dependent degeneration specifically of cerebellar granule neurons (not Purkinje cells or molecular layer cells) in old mice (>16 months), accompanied by increased oxidative stress markers (HNE, nitrotyrosine, protein carbonyl). Treatment with the mitochondria-targeted antioxidant SkQ1 from 6 weeks to 21 months prevented granule neuron loss and restored SOD2 and VDAC1 expression, demonstrating a causal role for mitochondrial oxidative stress in this neurodegeneration.\",\n      \"method\": \"Immp2l mutant mouse model, histology/immunohistochemistry, SkQ1 antioxidant treatment, immunofluorescence for SOD2 and VDAC1, oxidative stress marker quantification\",\n      \"journal\": \"Aging cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic model plus pharmacological rescue experiment with multiple orthogonal readouts; demonstrates causal role of ROS in IMMP2L-dependent neurodegeneration\",\n      \"pmids\": [\"26616244\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"IMMP2L transcription in human primary astrocytes requires Topoisomerase I. IMMP2L knockdown dysregulates genes involved in CNS development, and the transcriptional response partially overlaps with that induced by mitochondrial complex III inhibition.\",\n      \"method\": \"IMMP2L knockdown in human primary astrocytes, Topoisomerase I inhibition, transcriptome analysis (RNA-seq or microarray)\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — functional knockdown with transcriptomic readout in primary human cells; single lab, two methods (KD and TopoI inhibition comparison)\",\n      \"pmids\": [\"27932244\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"IMMP2L processes and activates at least two substrates: mitochondrial metabolic enzyme GPD2 and cell death regulator apoptosis-inducing factor (AIF). Shutdown of IMMP2L-GPD2 signaling reprograms mitochondria-associated redox status and phospholipid metabolism, while shutdown of IMMP2L-AIF signaling blocks cell death under oxidative stress. Coordinated loss of both axes drives the cellular senescence program.\",\n      \"method\": \"Multi-omics approaches, IMMP2L knockdown/knockout cell models, metabolic profiling, senescence assays, identification of GPD2 and AIF as substrates\",\n      \"journal\": \"Cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multi-omics approach with defined substrate identification (GPD2 and AIF), mechanistic dissection of two signaling axes, and in vivo aging validation; multiple orthogonal methods in one study\",\n      \"pmids\": [\"29808012\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In Immp2l-/- mice, follicle development is arrested at the secondary follicle stage due to mitochondrial dysfunction. The mechanism involves increased ROS, decreased estrogen levels, and altered Wnt/β-catenin and steroid hormone synthesis (CYP19A1) pathway gene expression. In vitro Immp2l knockdown in granulosa cells suppresses Wnt16, increases β-catenin, and decreases CYP19A1/estrogen, confirming the ROS-Wnt/β-catenin-estrogen pathway axis. Melatonin (antioxidant) treatment reverses these effects.\",\n      \"method\": \"Immp2l-/- mouse model, in vitro granulosa cell Immp2l knockdown, ROS measurement, hormone assays, Western blot/gene expression for Wnt pathway components, melatonin rescue experiment\",\n      \"journal\": \"Endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO plus in vitro KD with pharmacological rescue; multiple orthogonal biochemical and cellular readouts establishing pathway\",\n      \"pmids\": [\"32652035\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"IMMP2L/Immp2l cleaves the mitochondrial transit peptide from GPD2 (and CYC1), and this processing enhances GPD2 homodimeric structure and its respiratory function. In Immp2l-/- KO mice, glycerol-3-phosphate (G3P)-driven mitochondrial respiration is decreased (~20% female, ~7% male), nonmitochondrial respiration is dramatically lowered, AlphaFold2-Multimer structural modeling predicts altered Cyc1-cytochrome b interaction in Complex III and disrupted GPD2 homodimer structure. Primary MEF cells show ~27% decrease in total respiration and ~50% decrease in nonmitochondrial respiration.\",\n      \"method\": \"Immp2l-/- KO mouse model, substrate-specific mitochondrial respiration assays (G3P, succinate, glutamate), AlphaFold2-Multimer structural prediction, EchoMRI, mitoROS measurement, primary MEF cell lines\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with substrate-specific functional respiration assays; structural prediction is computational (Tier 4) but functional data is Tier 2; single lab\",\n      \"pmids\": [\"38256063\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In Immp2l-/- KO mice (complete knockout devoid of peptidase activity), ROS levels are significantly LOWERED (not elevated), and mice are fully fertile with no age-related ataxia or neurodegeneration. This contrasts with the elevated ROS phenotype of the earlier truncated Immp2l mutant (intragenic deletion) mouse model, suggesting that oxidative stress phenotypes previously attributed to IMMP2L loss may be specific to the truncated protein rather than complete absence of peptidase activity.\",\n      \"method\": \"Immp2l-/- KO mouse model, mitoROS measurement, fertility assessment, electron microscopy for neurodegeneration, MitoQ antioxidant treatment\",\n      \"journal\": \"Genes\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — complete KO mouse with multiple orthogonal readouts; a negative result (no elevated ROS) mechanistically informative and contradicts earlier studies; single lab\",\n      \"pmids\": [\"37761857\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In Immp2l-knockout granulosa cells, STAT1 expression is increased and controlled by S-glutathionylation and S-nitrosylation (not phosphorylation), as shown by Co-IP. Immp2l deficiency impairs UPRmt (unfolded protein response of mitochondria) and activates HIF1α/BNIP3-mediated mitophagy, but mitophagy is blocked due to reduced fusion of mitophagosomes and lysosomes, leading to mitochondria accumulation, increased ROS, and granulosa cell senescence.\",\n      \"method\": \"Immp2l knockout mouse/cell model, Co-IP for STAT1 modifications, Western blot for UPRmt and mitophagy pathway components, mitochondrial function assays, senescence assays, enocyanin treatment rescue\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and multiple pathway analyses in KO cells with pharmacological rescue; single lab, mechanistic pathway dissection\",\n      \"pmids\": [\"39456903\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Immp2l knockout induces mtDNA leakage from mitochondria into the cytoplasm via CyPD40 (inner membrane pore) and VDAC1 (outer membrane pore), both of which are upregulated. Cytoplasmic mtDNA activates cGAS-STING signaling and downstream interferon-stimulated genes, promoting SASP (senescence-associated secretory phenotype) and granulosa cell senescence. TFAM knockdown (siRNA) reduces cytoplasmic mtDNA and inhibits cGAS-STING activation, confirming TFAM-mediated mtDNA stability as a key regulatory node.\",\n      \"method\": \"Immp2l KO mouse/granulosa cell model, siRNA knockdown of TFAM, Western blot for cGAS-STING pathway components and CyPD40/VDAC1, cytoplasmic mtDNA measurement, SASP assays, PCB2 treatment rescue\",\n      \"journal\": \"International journal of biological macromolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO plus siRNA epistasis experiment with multiple pathway readouts; single lab, establishes mechanistic link between IMMP2L loss and innate immune activation via mtDNA leakage\",\n      \"pmids\": [\"40120895\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Immp2l+/- (heterozygous) mutation leads to mitochondrial membrane potential depolarization and suppression of mitochondrial respiratory Complex III activity after cerebral ischemia-reperfusion injury. This is accompanied by caspase-3 activation and AIF nuclear translocation, indicating activation of mitochondria-mediated apoptosis pathways.\",\n      \"method\": \"Immp2l+/- mouse model, middle cerebral artery occlusion (MCAO) ischemia-reperfusion model, JC-1 mitochondrial membrane potential assay, Complex III activity assay, caspase-3 Western blot, AIF nuclear translocation assay\",\n      \"journal\": \"Current medical science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — defined genetic model with multiple biochemical readouts in a disease context; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"37243806\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"IMMP2L encodes a mitochondrial inner membrane peptidase that cleaves the signal/transit peptides from nuclear-encoded mitochondrial proteins cytochrome c1 (CYC1) and glycerol-3-phosphate dehydrogenase 2 (GPD2), thereby enhancing GPD2 homodimeric structure, Gpd2-driven mitochondrial respiration, and CYC1/Complex III function; loss of IMMP2L activity impairs this processing and coordinately shuts down IMMP2L-GPD2 metabolic signaling and IMMP2L-AIF cell death signaling, reprogramming mitochondrial redox and phospholipid metabolism to drive cellular senescence, while also causing mtDNA leakage through CyPD40/VDAC1 pores that activates cGAS-STING innate immune signaling and SASP, and in vivo mutation leads to elevated superoxide, age-dependent reproductive failure, neurodegeneration, and accelerated aging phenotypes that are partially rescuable by mitochondria-targeted antioxidants.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"IMMP2L encodes the human homologue of the yeast mitochondrial inner membrane peptidase subunit 2, a gene first identified through chromosomal breakpoints at 7q31 in a Tourette syndrome patient [#0]. Its core molecular function is proteolytic cleavage of the signal/transit peptides from nuclear-encoded mitochondrial proteins, with cytochrome c1 (CYC1) and glycerol-3-phosphate dehydrogenase 2 (GPD2) established as substrates [#1, #9]. This processing matures GPD2 into its homodimeric, respiration-competent form and supports CYC1 function within Complex III, such that loss of IMMP2L lowers glycerol-3-phosphate-driven and nonmitochondrial respiration [#9]. Beyond metabolic enzymes, IMMP2L also processes apoptosis-inducing factor (AIF), and coordinated shutdown of the IMMP2L–GPD2 (redox/phospholipid) and IMMP2L–AIF (cell death) axes drives a cellular senescence program [#7]. In vivo, IMMP2L deficiency converges on mitochondrial dysfunction with downstream consequences including age-dependent reproductive failure, cerebellar granule neuron degeneration, and accelerated aging phenotypes, several of which are rescuable by mitochondria-targeted antioxidants [#2, #5, #8]. In granulosa cells, IMMP2L loss causes mtDNA leakage through CyPD40/VDAC1 pores that activates cGAS-STING innate immune signaling and the SASP [#12]. The redox direction of IMMP2L loss is allele-dependent: an intragenic-deletion (truncated) mutant elevates mitochondrial superoxide [#1, #2, #3], whereas a complete knockout lowers ROS and shows preserved fertility and no neurodegeneration [#10], indicating that some oxidative-stress phenotypes are specific to the truncated protein rather than absence of peptidase activity.\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Established the existence and genomic structure of human IMMP2L and a first disease association, framing it as a candidate mitochondrial peptidase subunit disrupted at 7q31.\",\n      \"evidence\": \"cDNA cloning, Southern blot, and FISH mapping in a Tourette syndrome patient\",\n      \"pmids\": [\"11254443\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No biochemical demonstration of peptidase activity\", \"Causal link to Tourette syndrome not established beyond breakpoint mapping\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined IMMP2L's molecular substrates by showing it is required for signal-peptide processing of CYC1 and GPD2, connecting loss of processing to mitochondrial hyperpolarization, elevated superoxide, and reproductive defects.\",\n      \"evidence\": \"Transgenic insertional Immp2l mutant mouse with membrane potential, superoxide, ATP, and protein-processing assays\",\n      \"pmids\": [\"18094351\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve whether ROS arises from the truncated protein or loss of activity per se\", \"Direct enzymatic cleavage in vitro not reconstituted\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Extended the processing defect to systemic consequences, linking IMMP2L-dependent mitochondrial ROS to adult stem cell dysfunction and accelerated aging phenotypes.\",\n      \"evidence\": \"Immp2l mutant mouse with oxidative-stress markers, colony formation, and adipogenic differentiation assays\",\n      \"pmids\": [\"21332923\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism connecting substrate misprocessing to ROS production not defined\", \"Tissue specificity of phenotypes unexplained\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Showed the ROS-mediated damage is age-dependent and not driven by mtDNA mutation, narrowing the mechanism to oxidative protein damage rather than genomic instability.\",\n      \"evidence\": \"Immp2l mutant mouse testis with protein carbonyl, TUNEL, and mtDNA mutation-rate assays\",\n      \"pmids\": [\"22569411\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Source of age-dependent onset unexplained\", \"Did not test antioxidant rescue in this tissue\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Complicated the respiratory-deficiency model by showing unprocessed CYC1/GPD2 retain enzymatic function and respiration is not diminished, arguing the phenotype is not a simple respiratory chain defect.\",\n      \"evidence\": \"Immp2l mutant mouse with enzyme activity and mitochondrial respiration measurements\",\n      \"pmids\": [\"25460737\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Negative result from a single lab\", \"Apparent tension with later KO respiration data unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrated causality of mitochondrial oxidative stress in IMMP2L-dependent neurodegeneration via pharmacological rescue, identifying cerebellar granule neurons as a selectively vulnerable cell type.\",\n      \"evidence\": \"Immp2l mutant mouse with histology and chronic SkQ1 mitochondria-targeted antioxidant treatment\",\n      \"pmids\": [\"26616244\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Basis of granule-neuron selectivity unknown\", \"Molecular link from misprocessing to ROS not defined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Connected IMMP2L expression regulation to Topoisomerase I and showed its knockdown dysregulates CNS-development genes overlapping with Complex III inhibition, linking IMMP2L loss to a transcriptional program.\",\n      \"evidence\": \"IMMP2L knockdown and Topoisomerase I inhibition with transcriptome profiling in human primary astrocytes\",\n      \"pmids\": [\"27932244\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Directness of transcriptional effects not established\", \"Mechanism of TopoI-dependent transcription unexplained\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified AIF as a second IMMP2L substrate and partitioned IMMP2L function into a GPD2-linked redox/phospholipid axis and an AIF-linked cell-death axis whose coordinated loss executes senescence.\",\n      \"evidence\": \"Multi-omics, knockdown/knockout cell models, metabolic profiling, and senescence assays\",\n      \"pmids\": [\"29808012\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct cleavage of AIF by IMMP2L not biochemically reconstituted\", \"How two axes are jointly sensed to trigger senescence unclear\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Mapped a tissue-level mechanism in ovary, showing IMMP2L loss arrests follicle development through a ROS–Wnt/β-catenin–estrogen (CYP19A1) axis reversible by antioxidant treatment.\",\n      \"evidence\": \"Immp2l-/- mouse and granulosa cell knockdown with hormone assays, Wnt-pathway Western blots, and melatonin rescue\",\n      \"pmids\": [\"32652035\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Link between mitochondrial ROS and Wnt regulation not molecularly defined\", \"Whether AIF or GPD2 axis dominates here untested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Quantified the respiratory consequence of complete knockout, showing reduced G3P-driven and nonmitochondrial respiration and predicting disrupted GPD2 homodimer and Cyc1–cytochrome b interaction, reaffirming a respiratory role for substrate processing.\",\n      \"evidence\": \"Immp2l-/- mice and MEFs with substrate-specific respiration assays and AlphaFold2-Multimer modeling\",\n      \"pmids\": [\"38256063\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural predictions are computational and unvalidated experimentally\", \"Tension with the earlier no-respiratory-deficit report unresolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Revealed that a complete knockout LOWERS ROS and preserves fertility and neurological health, indicating earlier oxidative phenotypes may be specific to the truncated allele rather than loss of peptidase activity.\",\n      \"evidence\": \"Immp2l-/- complete KO mouse with mitoROS, fertility, electron microscopy, and MitoQ treatment\",\n      \"pmids\": [\"37761857\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which the truncated protein gains a toxic ROS phenotype not defined\", \"Single lab; reconciliation with allele-specific phenotypes incomplete\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Showed IMMP2L dosage matters in acute injury, with heterozygous mutation suppressing Complex III activity and triggering caspase-3 and AIF nuclear translocation after cerebral ischemia-reperfusion.\",\n      \"evidence\": \"Immp2l+/- mice in an MCAO model with JC-1, Complex III activity, caspase-3, and AIF translocation assays\",\n      \"pmids\": [\"37243806\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether AIF translocation depends on IMMP2L processing of AIF not tested here\", \"Heterozygous-specific mechanism not isolated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Connected IMMP2L loss to impaired mitochondrial quality control, showing blocked HIF1α/BNIP3 mitophagy, defective UPRmt, and redox-controlled STAT1 upregulation driving granulosa-cell senescence.\",\n      \"evidence\": \"Immp2l KO cells with Co-IP of STAT1 modifications, mitophagy/UPRmt Western blots, and enocyanin rescue\",\n      \"pmids\": [\"39456903\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"STAT1 Co-IP modifications shown without reciprocal validation\", \"Causal ordering of UPRmt failure vs mitophagy block unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Established a mechanistic link from IMMP2L loss to innate immune activation, showing mtDNA leaks through upregulated CyPD40/VDAC1 pores to activate cGAS-STING and SASP, with TFAM knockdown as an epistatic suppressor.\",\n      \"evidence\": \"Immp2l KO granulosa cells with TFAM siRNA epistasis, cGAS-STING/CyPD40/VDAC1 Western blots, cytoplasmic mtDNA quantification, and PCB2 rescue\",\n      \"pmids\": [\"40120895\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct mechanism of pore upregulation by IMMP2L loss unknown\", \"Single lab; cell-type generality untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how the truncated-allele toxic-gain phenotype mechanistically differs from complete loss of peptidase activity, and whether direct enzymatic cleavage of GPD2, CYC1, and AIF can be reconstituted in vitro.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No in vitro reconstitution of IMMP2L peptidase on defined substrates\", \"Allele-dependent ROS direction not mechanistically explained\", \"Direct AIF cleavage by IMMP2L not biochemically demonstrated\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [1, 7, 9]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [1, 9]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [1, 9, 12]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [7, 9]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [1, 9]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [12]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [7, 13]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"GPD2\", \"CYC1\", \"AIF\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}