{"gene":"LONP2","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2023,"finding":"LONP2 depletion in COS-7 and U2OS cells causes accumulation of its substrate TYSND1 protease, demonstrating LONP2's role as a peroxisomal protease that degrades TYSND1; depletion also alters peroxisome size and numbers, impairs luminal protein import, and leads to cholesterol accumulation in endomembrane compartments, indicating LONP2 is required for cholesterol flux out of late endosomes.","method":"siRNA-mediated LONP2 silencing, proteomic analysis, fluorescence microscopy, lipid mass spectrometry in COS-7 and U2OS cell lines","journal":"Biology direct","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two cell lines, multiple orthogonal methods (proteomics, imaging, lipidomics), single lab","pmids":["37736739"],"is_preprint":false},{"year":2021,"finding":"In C. elegans, peroxisomal import stress (via knockdown of prx-5/PEX5) triggers NHR-49/PPARα- and MDT-15/MED15-dependent transcriptional upregulation of the peroxisomal Lon protease lonp-2/LONP2, establishing LONP2 as part of a peroxisomal retrograde signaling (PRS) pathway responsive to peroxisomal dysfunction.","method":"RNAi knockdown, transcriptomic and proteomic analyses, genetic epistasis in C. elegans","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis combined with transcriptomics and proteomics in a single lab, single organism system","pmids":["33472070"],"is_preprint":false},{"year":2018,"finding":"LONP2 (peroxisomal Lon protease) selectively degrades oxidatively damaged proteins within peroxisomes, thereby prolonging the functional lifespan of the organelle and maintaining peroxisomal protein homeostasis.","method":"Review synthesizing experimental findings from multiple prior studies on peroxisomal proteolysis","journal":"Physiological reviews","confidence":"Medium","confidence_rationale":"Tier 2 / Strong — conclusion supported by multiple independent experimental studies cited in the review, though this specific paper is a review","pmids":["29167332"],"is_preprint":false},{"year":2016,"finding":"LonP2 is the peroxisomal isoform of the Lon protease responsible for degrading oxidatively damaged proteins within peroxisomes, functionally analogous to the mitochondrial LonP1 but distinct in organelle localization; its activity is critical for peroxisomal protein quality control and is subject to age-related decline.","method":"Comparative biochemical and cell biology review of experimental literature on Lon protease isoforms","journal":"Biological reviews of the Cambridge Philosophical Society","confidence":"Medium","confidence_rationale":"Tier 2 / Strong — review consolidating multiple experimental studies establishing peroxisomal localization and proteolytic function; individual underlying experiments are Tier 1–2","pmids":["26852705"],"is_preprint":false},{"year":2020,"finding":"Loss of Atg7 (autophagy inhibition) in pancreatic β-cells leads to upregulation of Lonp2 expression, which is associated with facilitated maturation of ether lipid synthetic enzymes in peroxisomes, linking LONP2 to peroxisomal chaperone/protease function in ether lipid biosynthesis.","method":"Conditional Atg7 knockout in β-cells, lipidomics by mass spectrometry, gene expression analysis, MIN6 cell experiments","journal":"Molecular metabolism","confidence":"Low","confidence_rationale":"Tier 3 / Weak — LONP2 upregulation observed as correlative finding with ether lipid changes; direct mechanistic role not experimentally isolated for LONP2 specifically","pmids":["32504884"],"is_preprint":false},{"year":2018,"finding":"LONP2 knockdown in HeLa and SiHa cervical cancer cells reduces cell proliferation, migration, invasion, and reactive oxygen species (ROS) production, indicating LONP2 promotes cervical tumorigenesis via regulation of oxidative stress.","method":"siRNA knockdown, CCK8 cell viability assay, flow cytometry for apoptosis and cell cycle, immunofluorescence and flow cytometry for ROS, cell migration and invasion assays","journal":"Medical science monitor","confidence":"Low","confidence_rationale":"Tier 3 / Weak — functional KD phenotype established but no direct substrate or molecular mechanism identified; single lab, single cell type pair","pmids":["29502128"],"is_preprint":false},{"year":2022,"finding":"LONP2 silencing in head and neck squamous cell carcinoma (HNSCC) cells suppresses tumor growth in vitro and in vivo; RNA sequencing after LONP2 knockdown revealed downregulation of PLS3 (plastin 3, an actin-bundling protein), and PLS3 knockdown blocked cell proliferation induced by LONP2 overexpression, placing LONP2 upstream of PLS3 in a pro-proliferative pathway.","method":"siRNA knockdown, LONP2 overexpression, xenograft in vivo tumor model, RNA sequencing, cell proliferation and migration assays","journal":"Gene","confidence":"Low","confidence_rationale":"Tier 3 / Weak — epistasis via RNA-seq and rescue experiment, but mechanism linking LONP2 to PLS3 transcription not established; single lab","pmids":["36347334"],"is_preprint":false},{"year":2021,"finding":"miR-1287-5p directly targets LONP2 mRNA (negatively regulating LONP2 expression), and LONP2 is upregulated during oxygen-glucose deprivation/reperfusion (OGD/R) in SH-SY5Y neuronal cells; curcumin treatment reduces LONP2 expression by upregulating miR-1287-5p, thereby alleviating OGD/R-induced oxidative damage.","method":"Luciferase reporter assay confirming miR-1287-5p targeting of LONP2, miRNA overexpression/inhibition, OGD/R cell model, ROS measurement","journal":"Analytical cellular pathology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — miRNA-target relationship confirmed by luciferase assay but LONP2's specific mechanistic role in oxidative stress protection not directly dissected; single lab","pmids":["34589382"],"is_preprint":false}],"current_model":"LONP2 is an ATP-dependent serine protease localized to the peroxisomal matrix where it selectively degrades oxidatively damaged and misfolded proteins (including the substrate TYSND1), maintains peroxisomal protein homeostasis and organelle integrity, facilitates maturation of ether lipid synthetic enzymes, and is transcriptionally upregulated via NHR-49/PPARα- and MDT-15/MED15-dependent peroxisomal retrograde signaling in response to peroxisomal stress; its depletion disrupts cholesterol flux from late endosomes, activates the integrated stress response, and in cancer cell contexts promotes proliferation and migration at least partly through regulation of downstream targets such as PLS3."},"narrative":{"mechanistic_narrative":"LONP2 is the peroxisomal isoform of the ATP-dependent Lon protease, functioning in peroxisomal protein quality control by selectively degrading oxidatively damaged proteins within the organelle and thereby maintaining peroxisomal protein homeostasis and prolonging organelle functional lifespan [PMID:29167332, PMID:26852705]. A direct cellular substrate is the peroxisomal protease TYSND1, which accumulates upon LONP2 depletion; loss of LONP2 also alters peroxisome size and number and impairs luminal protein import, and disrupts cholesterol flux out of late endosomes [PMID:37736739]. LONP2 is transcriptionally controlled by a peroxisomal retrograde signaling pathway: peroxisomal import stress induces NHR-49/PPARα- and MDT-15/MED15-dependent upregulation of LONP2, coupling its expression to peroxisomal dysfunction [PMID:33472070]. Beyond these roles in peroxisomal proteostasis and stress signaling, LONP2 has been implicated in promoting proliferation and migration in cancer cell models, acting upstream of the actin-bundling protein PLS3 [PMID:36347334].","teleology":[{"year":2016,"claim":"Established LONP2 as the peroxisome-localized Lon protease isoform dedicated to degrading oxidatively damaged proteins, distinguishing it from the mitochondrial LonP1 and assigning it a protein quality-control role in peroxisomes.","evidence":"comparative biochemical and cell biology review of Lon protease isoform literature","pmids":["26852705"],"confidence":"Medium","gaps":["Review-level synthesis rather than a primary mechanistic experiment","No specific endogenous substrate identified","Age-related activity decline asserted but not mechanistically dissected"]},{"year":2018,"claim":"Consolidated the view that LONP2 selectively degrades oxidatively damaged peroxisomal proteins to maintain proteostasis and extend organelle lifespan, framing peroxisomal proteolysis as a homeostatic mechanism.","evidence":"review synthesizing prior experimental studies on peroxisomal proteolysis","pmids":["29167332"],"confidence":"Medium","gaps":["Review, not new primary data","Substrate selectivity determinants unresolved","Regulation of protease activity not defined"]},{"year":2021,"claim":"Defined the upstream regulation of LONP2 by showing that peroxisomal import stress drives NHR-49/PPARα- and MDT-15/MED15-dependent transcriptional upregulation, placing LONP2 within a peroxisomal retrograde signaling pathway responsive to organelle dysfunction.","evidence":"RNAi knockdown, transcriptomics/proteomics, and genetic epistasis in C. elegans","pmids":["33472070"],"confidence":"Medium","gaps":["Demonstrated in C. elegans; mammalian conservation of the PRS axis not shown here","Direct promoter-level regulation by the transcription factors not established","Downstream proteostatic consequences of induction not quantified"]},{"year":2023,"claim":"Identified TYSND1 as a LONP2 substrate and linked LONP2 to broader peroxisomal integrity and inter-organelle lipid trafficking, showing depletion alters peroxisome morphology, impairs luminal import, and blocks cholesterol egress from late endosomes.","evidence":"siRNA silencing with proteomics, fluorescence microscopy, and lipid mass spectrometry in COS-7 and U2OS cells","pmids":["37736739"],"confidence":"Medium","gaps":["Direct proteolytic cleavage of TYSND1 by LONP2 not reconstituted in vitro","Mechanism connecting peroxisomal LONP2 to late-endosomal cholesterol flux unresolved","Single lab, two cell lines"]},{"year":2020,"claim":"Linked LONP2 to ether lipid biosynthesis by showing autophagy loss in β-cells upregulates Lonp2 alongside facilitated maturation of ether lipid synthetic enzymes.","evidence":"conditional Atg7 knockout in β-cells, lipidomics, and gene expression analysis in MIN6 cells","pmids":["32504884"],"confidence":"Low","gaps":["LONP2 upregulation is correlative; its direct role in enzyme maturation not isolated","Causality between LONP2 and ether lipid changes untested","No substrate or biochemical mechanism shown"]},{"year":2018,"claim":"Implicated LONP2 in cervical tumorigenesis by showing knockdown reduces proliferation, migration, invasion, and ROS production.","evidence":"siRNA knockdown with viability, apoptosis/cell-cycle, ROS, and migration/invasion assays in HeLa and SiHa cells","pmids":["29502128"],"confidence":"Low","gaps":["No molecular substrate or mechanism linking LONP2 to ROS or tumor phenotype","Single cell-type pair, single lab","Whether effect is peroxisomal proteostasis-dependent unknown"]},{"year":2022,"claim":"Placed LONP2 upstream of the actin-bundling protein PLS3 in a pro-proliferative pathway in HNSCC, where LONP2 knockdown suppresses tumor growth and reduces PLS3, and PLS3 knockdown blocks LONP2-overexpression-driven proliferation.","evidence":"siRNA knockdown, overexpression, xenograft model, RNA-seq, and rescue assays in HNSCC cells","pmids":["36347334"],"confidence":"Low","gaps":["Mechanism linking LONP2 protease activity to PLS3 transcription not established","Whether the link is direct or indirect unknown","Single lab"]},{"year":2021,"claim":"Identified post-transcriptional regulation of LONP2 by miR-1287-5p and its induction during oxygen-glucose deprivation/reperfusion in neuronal cells.","evidence":"luciferase reporter assay, miRNA gain/loss of function, OGD/R model, and ROS measurement in SH-SY5Y cells","pmids":["34589382"],"confidence":"Low","gaps":["LONP2's specific protective or damaging role in OGD/R not directly dissected","miRNA-LONP2 axis effect on peroxisomal function untested","Single lab"]},{"year":null,"claim":"The biochemical determinants of LONP2 substrate selectivity and the mechanism coupling its peroxisomal proteolytic activity to downstream phenotypes (cholesterol flux, ether lipid maturation, PLS3 regulation, cancer proliferation) remain undefined.","evidence":"","pmids":[],"confidence":"Low","gaps":["No in vitro reconstitution of LONP2 protease activity on identified substrates","No structural model of human LONP2","Mechanistic basis of non-peroxisomal phenotypes unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,2,3]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[2,3]}],"localization":[{"term_id":"GO:0005777","term_label":"peroxisome","supporting_discovery_ids":[0,2,3]}],"pathway":[],"complexes":[],"partners":["TYSND1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q86WA8","full_name":"Lon protease homolog 2, peroxisomal","aliases":["Lon protease-like protein 2","Lon protease 2","Peroxisomal Lon protease","pLon"],"length_aa":852,"mass_kda":94.6,"function":"ATP-dependent serine protease that mediates the selective degradation of misfolded and unassembled polypeptides in the peroxisomal matrix. Necessary for type 2 peroxisome targeting signal (PTS2)-containing protein processing and facilitates peroxisome matrix protein import (By similarity). May indirectly regulate peroxisomal fatty acid beta-oxidation through degradation of the self-processed forms of TYSND1","subcellular_location":"Peroxisome matrix","url":"https://www.uniprot.org/uniprotkb/Q86WA8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LONP2","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"WNK1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/LONP2","total_profiled":1310},"omim":[{"mim_id":"617774","title":"LON PEPTIDASE 2, PEROXISOMAL; LONP2","url":"https://www.omim.org/entry/617774"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/LONP2"},"hgnc":{"alias_symbol":["MGC4840","LONP","LONPL"],"prev_symbol":[]},"alphafold":{"accession":"Q86WA8","domains":[{"cath_id":"2.30.130.40","chopping":"13-127","consensus_level":"high","plddt":75.9487,"start":13,"end":127},{"cath_id":"-","chopping":"161-226","consensus_level":"medium","plddt":77.462,"start":161,"end":226},{"cath_id":"-","chopping":"281-320","consensus_level":"high","plddt":88.149,"start":281,"end":320},{"cath_id":"3.40.50.300","chopping":"333-428_437-510","consensus_level":"high","plddt":86.3921,"start":333,"end":510},{"cath_id":"1.10.8.60","chopping":"514-581_625-645","consensus_level":"medium","plddt":86.6826,"start":514,"end":645},{"cath_id":"3.30.230.10","chopping":"647-835","consensus_level":"high","plddt":85.3169,"start":647,"end":835}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86WA8","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q86WA8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q86WA8-F1-predicted_aligned_error_v6.png","plddt_mean":77.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LONP2","jax_strain_url":"https://www.jax.org/strain/search?query=LONP2"},"sequence":{"accession":"Q86WA8","fasta_url":"https://rest.uniprot.org/uniprotkb/Q86WA8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q86WA8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86WA8"}},"corpus_meta":[{"pmid":"24149988","id":"PMC_24149988","title":"The 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depletion also alters peroxisome size and numbers, impairs luminal protein import, and leads to cholesterol accumulation in endomembrane compartments, indicating LONP2 is required for cholesterol flux out of late endosomes.\",\n      \"method\": \"siRNA-mediated LONP2 silencing, proteomic analysis, fluorescence microscopy, lipid mass spectrometry in COS-7 and U2OS cell lines\",\n      \"journal\": \"Biology direct\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two cell lines, multiple orthogonal methods (proteomics, imaging, lipidomics), single lab\",\n      \"pmids\": [\"37736739\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In C. elegans, peroxisomal import stress (via knockdown of prx-5/PEX5) triggers NHR-49/PPARα- and MDT-15/MED15-dependent transcriptional upregulation of the peroxisomal Lon protease lonp-2/LONP2, establishing LONP2 as part of a peroxisomal retrograde signaling (PRS) pathway responsive to peroxisomal dysfunction.\",\n      \"method\": \"RNAi knockdown, transcriptomic and proteomic analyses, genetic epistasis in C. elegans\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis combined with transcriptomics and proteomics in a single lab, single organism system\",\n      \"pmids\": [\"33472070\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"LONP2 (peroxisomal Lon protease) selectively degrades oxidatively damaged proteins within peroxisomes, thereby prolonging the functional lifespan of the organelle and maintaining peroxisomal protein homeostasis.\",\n      \"method\": \"Review synthesizing experimental findings from multiple prior studies on peroxisomal proteolysis\",\n      \"journal\": \"Physiological reviews\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conclusion supported by multiple independent experimental studies cited in the review, though this specific paper is a review\",\n      \"pmids\": [\"29167332\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"LonP2 is the peroxisomal isoform of the Lon protease responsible for degrading oxidatively damaged proteins within peroxisomes, functionally analogous to the mitochondrial LonP1 but distinct in organelle localization; its activity is critical for peroxisomal protein quality control and is subject to age-related decline.\",\n      \"method\": \"Comparative biochemical and cell biology review of experimental literature on Lon protease isoforms\",\n      \"journal\": \"Biological reviews of the Cambridge Philosophical Society\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Strong — review consolidating multiple experimental studies establishing peroxisomal localization and proteolytic function; individual underlying experiments are Tier 1–2\",\n      \"pmids\": [\"26852705\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Loss of Atg7 (autophagy inhibition) in pancreatic β-cells leads to upregulation of Lonp2 expression, which is associated with facilitated maturation of ether lipid synthetic enzymes in peroxisomes, linking LONP2 to peroxisomal chaperone/protease function in ether lipid biosynthesis.\",\n      \"method\": \"Conditional Atg7 knockout in β-cells, lipidomics by mass spectrometry, gene expression analysis, MIN6 cell experiments\",\n      \"journal\": \"Molecular metabolism\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — LONP2 upregulation observed as correlative finding with ether lipid changes; direct mechanistic role not experimentally isolated for LONP2 specifically\",\n      \"pmids\": [\"32504884\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"LONP2 knockdown in HeLa and SiHa cervical cancer cells reduces cell proliferation, migration, invasion, and reactive oxygen species (ROS) production, indicating LONP2 promotes cervical tumorigenesis via regulation of oxidative stress.\",\n      \"method\": \"siRNA knockdown, CCK8 cell viability assay, flow cytometry for apoptosis and cell cycle, immunofluorescence and flow cytometry for ROS, cell migration and invasion assays\",\n      \"journal\": \"Medical science monitor\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — functional KD phenotype established but no direct substrate or molecular mechanism identified; single lab, single cell type pair\",\n      \"pmids\": [\"29502128\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"LONP2 silencing in head and neck squamous cell carcinoma (HNSCC) cells suppresses tumor growth in vitro and in vivo; RNA sequencing after LONP2 knockdown revealed downregulation of PLS3 (plastin 3, an actin-bundling protein), and PLS3 knockdown blocked cell proliferation induced by LONP2 overexpression, placing LONP2 upstream of PLS3 in a pro-proliferative pathway.\",\n      \"method\": \"siRNA knockdown, LONP2 overexpression, xenograft in vivo tumor model, RNA sequencing, cell proliferation and migration assays\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — epistasis via RNA-seq and rescue experiment, but mechanism linking LONP2 to PLS3 transcription not established; single lab\",\n      \"pmids\": [\"36347334\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"miR-1287-5p directly targets LONP2 mRNA (negatively regulating LONP2 expression), and LONP2 is upregulated during oxygen-glucose deprivation/reperfusion (OGD/R) in SH-SY5Y neuronal cells; curcumin treatment reduces LONP2 expression by upregulating miR-1287-5p, thereby alleviating OGD/R-induced oxidative damage.\",\n      \"method\": \"Luciferase reporter assay confirming miR-1287-5p targeting of LONP2, miRNA overexpression/inhibition, OGD/R cell model, ROS measurement\",\n      \"journal\": \"Analytical cellular pathology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — miRNA-target relationship confirmed by luciferase assay but LONP2's specific mechanistic role in oxidative stress protection not directly dissected; single lab\",\n      \"pmids\": [\"34589382\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LONP2 is an ATP-dependent serine protease localized to the peroxisomal matrix where it selectively degrades oxidatively damaged and misfolded proteins (including the substrate TYSND1), maintains peroxisomal protein homeostasis and organelle integrity, facilitates maturation of ether lipid synthetic enzymes, and is transcriptionally upregulated via NHR-49/PPARα- and MDT-15/MED15-dependent peroxisomal retrograde signaling in response to peroxisomal stress; its depletion disrupts cholesterol flux from late endosomes, activates the integrated stress response, and in cancer cell contexts promotes proliferation and migration at least partly through regulation of downstream targets such as PLS3.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"LONP2 is the peroxisomal isoform of the ATP-dependent Lon protease, functioning in peroxisomal protein quality control by selectively degrading oxidatively damaged proteins within the organelle and thereby maintaining peroxisomal protein homeostasis and prolonging organelle functional lifespan [#2, #3]. A direct cellular substrate is the peroxisomal protease TYSND1, which accumulates upon LONP2 depletion; loss of LONP2 also alters peroxisome size and number and impairs luminal protein import, and disrupts cholesterol flux out of late endosomes [#0]. LONP2 is transcriptionally controlled by a peroxisomal retrograde signaling pathway: peroxisomal import stress induces NHR-49/PPARα- and MDT-15/MED15-dependent upregulation of LONP2, coupling its expression to peroxisomal dysfunction [#1]. Beyond these roles in peroxisomal proteostasis and stress signaling, LONP2 has been implicated in promoting proliferation and migration in cancer cell models, acting upstream of the actin-bundling protein PLS3 [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 2016,\n      \"claim\": \"Established LONP2 as the peroxisome-localized Lon protease isoform dedicated to degrading oxidatively damaged proteins, distinguishing it from the mitochondrial LonP1 and assigning it a protein quality-control role in peroxisomes.\",\n      \"evidence\": \"comparative biochemical and cell biology review of Lon protease isoform literature\",\n      \"pmids\": [\"26852705\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Review-level synthesis rather than a primary mechanistic experiment\", \"No specific endogenous substrate identified\", \"Age-related activity decline asserted but not mechanistically dissected\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Consolidated the view that LONP2 selectively degrades oxidatively damaged peroxisomal proteins to maintain proteostasis and extend organelle lifespan, framing peroxisomal proteolysis as a homeostatic mechanism.\",\n      \"evidence\": \"review synthesizing prior experimental studies on peroxisomal proteolysis\",\n      \"pmids\": [\"29167332\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Review, not new primary data\", \"Substrate selectivity determinants unresolved\", \"Regulation of protease activity not defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined the upstream regulation of LONP2 by showing that peroxisomal import stress drives NHR-49/PPARα- and MDT-15/MED15-dependent transcriptional upregulation, placing LONP2 within a peroxisomal retrograde signaling pathway responsive to organelle dysfunction.\",\n      \"evidence\": \"RNAi knockdown, transcriptomics/proteomics, and genetic epistasis in C. elegans\",\n      \"pmids\": [\"33472070\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Demonstrated in C. elegans; mammalian conservation of the PRS axis not shown here\", \"Direct promoter-level regulation by the transcription factors not established\", \"Downstream proteostatic consequences of induction not quantified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified TYSND1 as a LONP2 substrate and linked LONP2 to broader peroxisomal integrity and inter-organelle lipid trafficking, showing depletion alters peroxisome morphology, impairs luminal import, and blocks cholesterol egress from late endosomes.\",\n      \"evidence\": \"siRNA silencing with proteomics, fluorescence microscopy, and lipid mass spectrometry in COS-7 and U2OS cells\",\n      \"pmids\": [\"37736739\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct proteolytic cleavage of TYSND1 by LONP2 not reconstituted in vitro\", \"Mechanism connecting peroxisomal LONP2 to late-endosomal cholesterol flux unresolved\", \"Single lab, two cell lines\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Linked LONP2 to ether lipid biosynthesis by showing autophagy loss in β-cells upregulates Lonp2 alongside facilitated maturation of ether lipid synthetic enzymes.\",\n      \"evidence\": \"conditional Atg7 knockout in β-cells, lipidomics, and gene expression analysis in MIN6 cells\",\n      \"pmids\": [\"32504884\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"LONP2 upregulation is correlative; its direct role in enzyme maturation not isolated\", \"Causality between LONP2 and ether lipid changes untested\", \"No substrate or biochemical mechanism shown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Implicated LONP2 in cervical tumorigenesis by showing knockdown reduces proliferation, migration, invasion, and ROS production.\",\n      \"evidence\": \"siRNA knockdown with viability, apoptosis/cell-cycle, ROS, and migration/invasion assays in HeLa and SiHa cells\",\n      \"pmids\": [\"29502128\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No molecular substrate or mechanism linking LONP2 to ROS or tumor phenotype\", \"Single cell-type pair, single lab\", \"Whether effect is peroxisomal proteostasis-dependent unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Placed LONP2 upstream of the actin-bundling protein PLS3 in a pro-proliferative pathway in HNSCC, where LONP2 knockdown suppresses tumor growth and reduces PLS3, and PLS3 knockdown blocks LONP2-overexpression-driven proliferation.\",\n      \"evidence\": \"siRNA knockdown, overexpression, xenograft model, RNA-seq, and rescue assays in HNSCC cells\",\n      \"pmids\": [\"36347334\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Mechanism linking LONP2 protease activity to PLS3 transcription not established\", \"Whether the link is direct or indirect unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified post-transcriptional regulation of LONP2 by miR-1287-5p and its induction during oxygen-glucose deprivation/reperfusion in neuronal cells.\",\n      \"evidence\": \"luciferase reporter assay, miRNA gain/loss of function, OGD/R model, and ROS measurement in SH-SY5Y cells\",\n      \"pmids\": [\"34589382\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"LONP2's specific protective or damaging role in OGD/R not directly dissected\", \"miRNA-LONP2 axis effect on peroxisomal function untested\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The biochemical determinants of LONP2 substrate selectivity and the mechanism coupling its peroxisomal proteolytic activity to downstream phenotypes (cholesterol flux, ether lipid maturation, PLS3 regulation, cancer proliferation) remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No in vitro reconstitution of LONP2 protease activity on identified substrates\", \"No structural model of human LONP2\", \"Mechanistic basis of non-peroxisomal phenotypes unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [2, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005777\", \"supporting_discovery_ids\": [0, 2, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0005777\", \"supporting_discovery_ids\": []}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"TYSND1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":4,"faith_total":4,"faith_pct":100.0}}