{"gene":"GPD2","run_date":"2026-06-10T01:55:21","timeline":{"discoveries":[{"year":1997,"finding":"In S. cerevisiae, GPD2 encodes one of two isoenzymes of NAD+-dependent glycerol 3-phosphate dehydrogenase; GPD2 (unlike GPD1) is specifically induced by anaerobic/anoxic conditions and is required for anaerobic growth, functioning as a redox sink for excess cytosolic NADH. Its anaerobic induction is independent of the HOG pathway that controls osmotic induction of GPD1.","method":"Gene deletion (gpd1Δ, gpd2Δ, double mutant), anaerobic growth assays, NADH accumulation measurements, acetaldehyde rescue experiment, CAT reporter gene transcriptional analysis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal genetic and biochemical methods, replicated across deletion backgrounds, mechanistic rescue with acetaldehyde","pmids":["9171333"],"is_preprint":false},{"year":1995,"finding":"GPD2 encodes an sn-glycerol 3-phosphate dehydrogenase (NAD+) in S. cerevisiae sharing 69% identity with GPD1; GPD2 overexpression increases GPDH enzyme activity, and its promoter activity is decreased on non-fermentable carbon sources and is not induced by osmotic stress or heat shock.","method":"Gene cloning, disruption, overexpression, CAT reporter gene fusion transcriptional analysis, enzyme activity assay","journal":"Molecular microbiology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — direct enzyme activity assay combined with genetic disruption and promoter-reporter analysis in multiple conditions","pmids":["7476212"],"is_preprint":false},{"year":2019,"finding":"In LPS-activated macrophages, GPD2 (mitochondrial glycerol 3-phosphate dehydrogenase, a component of the glycerol phosphate shuttle) boosts glucose oxidation to fuel acetyl-CoA production, driving histone acetylation at inflammatory gene loci. During prolonged LPS exposure (tolerance), GPD2 coordinates a shutdown of oxidative metabolism, limiting acetyl-CoA availability for histone acetylation and suppressing inflammatory gene expression.","method":"GPD2 loss-of-function in macrophages, metabolic flux analysis, histone acetylation assays, gene expression analysis in LPS-stimulated and LPS-tolerant macrophages","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (metabolomics, histone acetylation, gene expression) with loss-of-function, published in high-impact journal with author correction confirming study validity","pmids":["31384058","31551573"],"is_preprint":false},{"year":2008,"finding":"GPD2 encodes mitochondrial glycerophosphate dehydrogenase (mGPDH), located on the outer surface of the inner mitochondrial membrane, catalyzing the unidirectional conversion of glycerol-3-phosphate (G3P) to dihydroxyacetone phosphate with concomitant reduction of enzyme-bound FAD. Haploinsufficiency of GPD2 leads to ~50% reduction in mGPDH transcript and activity in patient lymphoblastoid cell lines.","method":"FISH mapping of chromosomal breakpoint, molecular transcript quantification, functional enzyme activity assay in patient-derived lymphoblastoid cell lines","journal":"Human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct enzymatic activity measurement and transcript quantification in patient cells, single lab, no orthogonal structural validation","pmids":["19011903"],"is_preprint":false},{"year":2013,"finding":"A hemizygous GPD2 missense mutation (p.Pro205Leu) combined with chromosomal deletion results in completely absent GPD2 enzymatic activity, while heterozygous carriers (mother, sister) have ~50% activity, establishing this residue as critical for enzymatic function.","method":"aCGH deletion mapping, Sanger sequencing, functional enzyme activity assay in patient-derived cells","journal":"American journal of medical genetics. Part A","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct functional enzyme assay with clear genotype-activity correlation; single lab, no structural validation","pmids":["23554088"],"is_preprint":false},{"year":2021,"finding":"Under ischemic conditions in cardiomyocytes, GPD2 is activated and converts glycerol-3-phosphate to dihydroxyacetone phosphate to facilitate ATP synthesis from glycerol. GPD2 deficiency exacerbates cardiac dysfunction after acute myocardial infarction, placing GPD2 downstream of LPL/AQP7-mediated glycerol supply in a cardioprotective pathway.","method":"GPD2-deficient mouse model, myocardial infarction (coronary ligation) model, cardiac function measurements, metabolic activity assays, cardiomyocyte-specific LPL and AQP7 deficiency models","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KO with defined cardiac phenotype and pathway placement, single lab","pmids":["34807469"],"is_preprint":false},{"year":2023,"finding":"GPD2 KO in cancer cells suppresses tumor growth not through its conventional bioenergetic role but by reducing dihydroxyacetone phosphate (DHAP) supply for ether lipid biosynthesis. Reduced ether lipid levels downregulate the Akt/mTORC1 pathway, and cell growth is rescued by supplementation with a DHAP precursor or ether lipids, defining a GPD2-ether lipid-Akt signaling axis.","method":"GPD2 knockout cells, in vivo tumor growth assay, multi-omics (metabolomics, transcriptomics, lipidomics), DHAP precursor and ether lipid supplementation rescue experiments","journal":"Theranostics","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (KO, metabolomics, lipidomics, pathway rescue), in vitro and in vivo validation, single lab","pmids":["36632231"],"is_preprint":false},{"year":2022,"finding":"Mitochondrial GCN5L1 directly binds GPD2 and modulates its enzymatic activity, regulating the glycerol phosphate shuttle and thereby controlling cytosolic redox state and hepatic gluconeogenesis from glycerol and lactate.","method":"GCN5L1 deletion cells/mice, gluconeogenesis assays, cytosolic redox measurement, co-immunoprecipitation of GCN5L1 and GPD2","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP binding plus functional activity assay; single lab, moderate mechanistic detail in abstract","pmids":["35802941"],"is_preprint":false},{"year":2024,"finding":"IMMP2L mitochondrial peptidase cleaves the mitochondrial transit peptide of GPD2; loss of IMMP2L reduces GPD2-mediated glycerol-3-phosphate-driven mitochondrial respiration (~20% decrease in females, ~7% in males) and alters the homodimeric structure of GPD2 within the inner mitochondrial membrane.","method":"Immp2l knockout mouse, substrate-specific mitochondrial respiration assays (G3P as substrate), AlphaFold2-Multimer structural prediction, EchoMRI, primary MEF cell lines","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct respiratory substrate assay in KO mouse tissues plus structural modeling; single lab, structural prediction is computational","pmids":["38256063"],"is_preprint":false},{"year":2020,"finding":"In CD133-positive HuH-7 hepatocarcinoma cells, GPD2 knockdown strongly reduces glycerol-3-phosphate-driven ATP synthesis (G3P-ATPase activity) and decreases anchorage-independent cell proliferation. p38 signaling downstream of CD133 regulates GPD2 expression and G3P-ATPase activity.","method":"GPD2 knockdown, G3P-driven ATP synthesis assay, p38 inhibitor treatment, anchorage-independent growth assay, CD133-positive cell sorting","journal":"Genes to cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KD with direct enzymatic activity readout and defined cellular phenotype; single lab, pathway placement via inhibitor only","pmids":["31887237"],"is_preprint":false},{"year":2024,"finding":"Mitochondrial SPARC interacts with GPD2 (identified by co-immunoprecipitation), modulates GPD2 expression levels, and thereby regulates GPD2-mediated mitochondrial respiration to control migration and invasion of hepatocellular carcinoma cells.","method":"Cellular fractionation, immunofluorescence, Proteinase K protection assay for SPARC mitochondrial localization, co-immunoprecipitation (SPARC-GPD2), Seahorse XF Mito Stress Test, shRNA knockdown","journal":"Biochemical genetics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP plus functional mitochondrial respiration assay and phenotypic readout; single lab","pmids":["38334876"],"is_preprint":false},{"year":2025,"finding":"GPD2 methylation at CpG site cg03230175 in its promoter region reduces GPD2 expression, suppresses mitochondrial energy metabolism, decreases ROS production, attenuates NF-κB activation, and reduces P2Y12 expression, ultimately inhibiting coagulation/platelet function. GPD2 enzyme inhibition prolongs clotting time in mice.","method":"850k methylation array, EWAS, CRISPR-dCas9-DNMT3A/Tet1CD epigenome editing, transcriptomic sequencing, cellular ROS/NF-κB/P2Y12 measurements, animal clotting assay","journal":"Cellular & molecular biology letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct epigenome editing with mechanistic pathway readouts plus in vivo validation; single lab","pmids":["40682019"],"is_preprint":false},{"year":2024,"finding":"Lactate secreted by cervical cancer cells upregulates H3K18 lactylation at the GPD2 locus in macrophages, driving GPD2 expression; GPD2 knockdown in macrophages reverses lactate-induced M2 polarization, establishing a lactate→histone lactylation→GPD2→M2 macrophage polarization axis.","method":"ChIP-seq for H3K18la, GPD2 knockdown in macrophages, conditioned medium experiments, M1/M2 marker measurement","journal":"DNA and cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP-seq plus KD rescue with defined functional readout; single lab","pmids":["39504115"],"is_preprint":false},{"year":2020,"finding":"GPD2 binds directly to GPI (glucose-6-phosphate isomerase) as detected by microscale thermophoresis and protein interaction assays; esculetin binds GPD2 (and PGK2, GPI) and inhibits glycolytic flux as measured by lactate production and glucose consumption in HepG2 cells.","method":"Microscale thermophoresis (MST) binding assay, transcriptome/proteomics/reverse docking target identification, cellular glycolysis assay (lactate, glucose), animal xenograft","journal":"Frontiers in pharmacology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — MST binding and indirect cellular assay; single lab, limited mechanistic specificity for GPD2 alone","pmids":["32292350"],"is_preprint":false},{"year":2025,"finding":"GPD2 knockdown in septic mice (CLP model) exacerbates lung injury by promoting ferroptosis; GPX4 activator (SeMet) reverses this, suggesting GPD2 suppresses ferroptosis through activation of the GPX4 pathway in the lung.","method":"AAV-mediated GPD2 knockdown, CLP sepsis mouse model, ferroptosis markers, GPX4 activator (SeMet) rescue, lung injury phenotype quantification","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KO with defined ferroptosis pathway rescue; single lab, pathway placement via pharmacological rescue only","pmids":["41313944"],"is_preprint":false}],"current_model":"GPD2 encodes mitochondrial glycerol-3-phosphate dehydrogenase (mGPDH), an FAD-linked enzyme located on the outer surface of the inner mitochondrial membrane that catalyzes the unidirectional oxidation of glycerol-3-phosphate (G3P) to dihydroxyacetone phosphate (DHAP), coupling cytosolic NADH reoxidation to mitochondrial electron transport via the glycerol phosphate shuttle; in macrophages this shuttle drives glucose oxidation and acetyl-CoA-dependent histone acetylation to regulate inflammatory gene expression, in cancer cells GPD2 supplies DHAP for ether lipid biosynthesis to sustain Akt/mTORC1 signaling and proliferation, in cardiomyocytes it supports ATP production from glycerol during ischemia, and its activity is regulated by IMMP2L-mediated transit peptide cleavage and by direct interaction with GCN5L1 and SPARC."},"narrative":{"mechanistic_narrative":"GPD2 encodes a glycerol-3-phosphate dehydrogenase that catalyzes the unidirectional, FAD-coupled oxidation of glycerol-3-phosphate (G3P) to dihydroxyacetone phosphate (DHAP), serving as the mitochondrial arm of the glycerol phosphate shuttle that reoxidizes cytosolic reducing equivalents [PMID:19011903]. In its yeast origins, the GPD2 isoform was defined genetically as an anaerobically induced, NAD+-dependent enzyme acting as a redox sink for excess cytosolic NADH, distinct in regulation from its paralog GPD1 [PMID:9171333, PMID:7476212]. Across mammalian systems, this single catalytic activity is repurposed for divergent physiological outputs: it boosts glucose oxidation to generate acetyl-CoA for histone acetylation at inflammatory loci in LPS-activated macrophages [PMID:31384058, PMID:31551573], supplies DHAP for ether lipid biosynthesis that sustains Akt/mTORC1 signaling and tumor growth in cancer cells [PMID:36632231], and supports G3P-driven ATP synthesis that is cardioprotective during ischemia downstream of LPL/AQP7-mediated glycerol supply [PMID:34807469]. GPD2 enzymatic activity is set by its expression and by direct protein partners — the mitochondrial regulator GCN5L1 binds GPD2 to control the shuttle and hepatic gluconeogenesis [PMID:35802941], SPARC binds GPD2 to tune respiration and HCC cell migration [PMID:38334876] — and by IMMP2L-mediated cleavage of its mitochondrial transit peptide, which affects respiration and its homodimeric assembly in the inner membrane [PMID:38256063]. Human GPD2 haploinsufficiency and a loss-of-function p.Pro205Leu mutation reduce or abolish mGPDH enzyme activity in patient cells [PMID:19011903, PMID:23554088].","teleology":[{"year":1995,"claim":"Establishing that GPD2 encodes a functional NAD+-dependent glycerol-3-phosphate dehydrogenase defined the gene's core catalytic identity and showed its expression is carbon-source dependent but not stress-induced.","evidence":"Gene cloning, disruption, overexpression with enzyme activity assay and promoter-reporter analysis in S. cerevisiae","pmids":["7476212"],"confidence":"High","gaps":["Did not resolve the physiological condition selecting for GPD2 over GPD1","No mammalian context"]},{"year":1997,"claim":"Genetic dissection answered why a second isoenzyme exists, showing GPD2 is specifically required under anaerobic conditions as a redox sink for excess cytosolic NADH, regulated independently of the osmotic HOG pathway.","evidence":"Deletion mutants, anaerobic growth assays, NADH measurements and acetaldehyde rescue in yeast","pmids":["9171333"],"confidence":"High","gaps":["Yeast NAD+-dependent activity differs from mammalian FAD-coupled mitochondrial enzyme","Membrane topology not addressed"]},{"year":2008,"claim":"Characterizing the human enzyme established GPD2 as mitochondrial glycerophosphate dehydrogenase on the inner membrane catalyzing unidirectional G3P-to-DHAP conversion, and linked gene dosage to enzyme activity in patients.","evidence":"FISH breakpoint mapping, transcript quantification and enzyme activity assay in patient lymphoblastoid lines","pmids":["19011903"],"confidence":"Medium","gaps":["No structural validation","Single lab","Disease causality from haploinsufficiency alone not firmly established"]},{"year":2013,"claim":"A genotype-activity correlation identified residue Pro205 as critical, showing combined hemizygous missense plus deletion abolishes activity while heterozygotes retain ~50%.","evidence":"aCGH, Sanger sequencing and enzyme activity assays in patient-derived cells","pmids":["23554088"],"confidence":"Medium","gaps":["No structural mechanism for how Pro205Leu impairs catalysis","Single family"]},{"year":2019,"claim":"Connecting GPD2 flux to chromatin showed the shuttle drives glucose oxidation and acetyl-CoA-dependent histone acetylation to set inflammatory gene expression in macrophages and to enforce LPS tolerance.","evidence":"Macrophage loss-of-function, metabolic flux, histone acetylation and gene expression analyses","pmids":["31384058","31551573"],"confidence":"High","gaps":["Direct enzymatic coupling to specific histone marks not biochemically reconstituted","Mechanism of tolerance-phase shutdown unresolved"]},{"year":2020,"claim":"Cancer studies tied GPD2-driven G3P-ATP synthesis to malignant phenotype and placed GPD2 expression downstream of CD133/p38 signaling.","evidence":"GPD2 knockdown, G3P-ATP synthesis assay, p38 inhibition and anchorage-independent growth in CD133+ hepatocarcinoma cells","pmids":["31887237"],"confidence":"Medium","gaps":["Pathway placement relies on inhibitor only","Single lab"]},{"year":2021,"claim":"An in vivo KO defined a cardioprotective role, showing GPD2 enables ATP synthesis from glycerol during ischemia downstream of LPL/AQP7 glycerol supply.","evidence":"GPD2-deficient mouse, myocardial infarction model, cardiac function and metabolic assays with LPL/AQP7 KO","pmids":["34807469"],"confidence":"Medium","gaps":["Single lab","Mechanism of GPD2 activation under ischemia not detailed"]},{"year":2022,"claim":"Identifying GCN5L1 as a direct binding partner revealed protein-level regulation of GPD2 activity that controls cytosolic redox and hepatic gluconeogenesis.","evidence":"Co-IP, GCN5L1 deletion cells/mice, gluconeogenesis and cytosolic redox assays","pmids":["35802941"],"confidence":"Medium","gaps":["No reciprocal validation or binding interface mapped","Single lab"]},{"year":2023,"claim":"Multi-omics with rescue redefined GPD2's oncogenic role as biosynthetic rather than purely bioenergetic, establishing a GPD2-DHAP-ether lipid-Akt/mTORC1 axis.","evidence":"GPD2 KO cells, in vivo tumor growth, metabolomics/lipidomics, DHAP precursor and ether lipid rescue","pmids":["36632231"],"confidence":"High","gaps":["Direct enzyme-to-ether-lipid flux not measured in real time","Single lab"]},{"year":2024,"claim":"Several findings established additional layers of GPD2 regulation: IMMP2L cleaves its transit peptide affecting respiration and dimer structure, SPARC binds and tunes GPD2-dependent respiration in HCC, and lactate-induced H3K18 lactylation drives GPD2 to promote M2 macrophage polarization.","evidence":"Immp2l KO mice with substrate respiration and AlphaFold2 modeling; SPARC-GPD2 co-IP with Seahorse assays; H3K18la ChIP-seq with GPD2 knockdown","pmids":["38256063","38334876","39504115"],"confidence":"Medium","gaps":["Structural effect of IMMP2L cleavage is computational","SPARC and GCN5L1 binding interfaces unmapped","Lactylation-to-transcription mechanism incomplete"]},{"year":2025,"claim":"Newer studies extended GPD2 to platelet function via promoter methylation suppressing energy metabolism/NF-kB/P2Y12, and to anti-ferroptosis protection in sepsis-induced lung injury via the GPX4 pathway.","evidence":"CRISPR-dCas9 epigenome editing with clotting assays; AAV knockdown in CLP sepsis with GPX4 activator rescue","pmids":["40682019","41313944"],"confidence":"Medium","gaps":["GPX4-GPD2 link rests on pharmacological rescue only","Mechanism connecting enzymatic activity to ferroptosis unresolved"]},{"year":null,"claim":"How a single G3P-DHAP catalytic activity is mechanistically routed to such divergent outputs (chromatin acetylation, ether lipid synthesis, redox, ferroptosis) and how its partner interactions structurally regulate catalysis remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No experimental atomic structure of human GPD2","Binding interfaces for GCN5L1/SPARC undefined","Determinants selecting bioenergetic vs biosynthetic flux unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016491","term_label":"oxidoreductase activity","supporting_discovery_ids":[0,1,3,4]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[3,8]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[3,8,10]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[2,5,6]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,12]}],"complexes":[],"partners":["GCN5L1","SPARC","IMMP2L","GPI"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P43304","full_name":"Glycerol-3-phosphate dehydrogenase, mitochondrial","aliases":["mitochondrial glycerophosphate dehydrogenase gene","mGDH","mtGPD"],"length_aa":727,"mass_kda":80.9,"function":"Calcium-responsive mitochondrial glycerol-3-phosphate dehydrogenase which seems to be a key component of the pancreatic beta-cell glucose-sensing device","subcellular_location":"Mitochondrion","url":"https://www.uniprot.org/uniprotkb/P43304/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/GPD2","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":[],"url":"https://opencell.sf.czbiohub.org/search/GPD2","total_profiled":1310},"omim":[{"mim_id":"603859","title":"SOLUTE CARRIER FAMILY 25 (CITRIN), MEMBER 13; SLC25A13","url":"https://www.omim.org/entry/603859"},{"mim_id":"603471","title":"CITRIN DEFICIENCY, ADOLESCENT OR ADULT ONSET; CDAA","url":"https://www.omim.org/entry/603471"},{"mim_id":"138430","title":"GLYCEROL-3-PHOSPHATE DEHYDROGENASE 2; GPD2","url":"https://www.omim.org/entry/138430"},{"mim_id":"138420","title":"GLYCEROL-3-PHOSPHATE DEHYDROGENASE 1; GPD1","url":"https://www.omim.org/entry/138420"},{"mim_id":"125853","title":"TYPE 2 DIABETES MELLITUS; T2D","url":"https://www.omim.org/entry/125853"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Mitochondria","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/GPD2"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"P43304","domains":[{"cath_id":"3.50.50.60","chopping":"56-108_226-307_407-454","consensus_level":"high","plddt":93.966,"start":56,"end":454},{"cath_id":"3.30.9.10","chopping":"153-222_310-402","consensus_level":"medium","plddt":90.4939,"start":153,"end":402},{"cath_id":"1.10.8.870","chopping":"477-610","consensus_level":"medium","plddt":94.793,"start":477,"end":610},{"cath_id":"1.10.238.10","chopping":"621-713","consensus_level":"high","plddt":77.9213,"start":621,"end":713}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P43304","model_url":"https://alphafold.ebi.ac.uk/files/AF-P43304-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P43304-F1-predicted_aligned_error_v6.png","plddt_mean":86.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=GPD2","jax_strain_url":"https://www.jax.org/strain/search?query=GPD2"},"sequence":{"accession":"P43304","fasta_url":"https://rest.uniprot.org/uniprotkb/P43304.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P43304/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P43304"}},"corpus_meta":[{"pmid":"9171333","id":"PMC_9171333","title":"The two isoenzymes for yeast NAD+-dependent glycerol 3-phosphate dehydrogenase encoded by GPD1 and GPD2 have distinct roles in osmoadaptation and redox regulation.","date":"1997","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/9171333","citation_count":390,"is_preprint":false},{"pmid":"31384058","id":"PMC_31384058","title":"Glycerol phosphate shuttle enzyme GPD2 regulates macrophage inflammatory responses.","date":"2019","source":"Nature immunology","url":"https://pubmed.ncbi.nlm.nih.gov/31384058","citation_count":167,"is_preprint":false},{"pmid":"7476212","id":"PMC_7476212","title":"Cloning and characterization of GPD2, a second gene encoding sn-glycerol 3-phosphate dehydrogenase (NAD+) in Saccharomyces cerevisiae, and its comparison with GPD1.","date":"1995","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/7476212","citation_count":120,"is_preprint":false},{"pmid":"21724879","id":"PMC_21724879","title":"Gpd1 and Gpd2 fine-tuning for sustainable reduction of glycerol formation in Saccharomyces cerevisiae.","date":"2011","source":"Applied and environmental microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/21724879","citation_count":61,"is_preprint":false},{"pmid":"32292350","id":"PMC_32292350","title":"Esculetin Inhibits Cancer Cell Glycolysis by Binding Tumor PGK2, GPD2, and GPI.","date":"2020","source":"Frontiers in pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/32292350","citation_count":39,"is_preprint":false},{"pmid":"39504115","id":"PMC_39504115","title":"Histone Lactylation-Driven GPD2 Mediates M2 Macrophage Polarization to Promote Malignant Transformation of Cervical Cancer Progression.","date":"2024","source":"DNA and cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/39504115","citation_count":29,"is_preprint":false},{"pmid":"19011903","id":"PMC_19011903","title":"Haploinsufficiency of the GPD2 gene in a patient with nonsyndromic mental retardation.","date":"2008","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19011903","citation_count":23,"is_preprint":false},{"pmid":"35964044","id":"PMC_35964044","title":"Ethanol yield improvement in Saccharomyces cerevisiae GPD2 Delta FPS1 Delta ADH2 Delta DLD3 Delta mutant and molecular mechanism exploration based on the metabolic flux and transcriptomics approaches.","date":"2022","source":"Microbial cell factories","url":"https://pubmed.ncbi.nlm.nih.gov/35964044","citation_count":21,"is_preprint":false},{"pmid":"34807469","id":"PMC_34807469","title":"LPL/AQP7/GPD2 promotes glycerol metabolism under hypoxia and prevents cardiac dysfunction during ischemia.","date":"2021","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/34807469","citation_count":21,"is_preprint":false},{"pmid":"36632231","id":"PMC_36632231","title":"Non-bioenergetic roles of mitochondrial GPD2 promote tumor progression.","date":"2023","source":"Theranostics","url":"https://pubmed.ncbi.nlm.nih.gov/36632231","citation_count":20,"is_preprint":false},{"pmid":"35887459","id":"PMC_35887459","title":"CRISPR-Cas9 Approach Constructed Engineered Saccharomyces cerevisiae with the Deletion of GPD2, FPS1, and ADH2 to Enhance the Production of Ethanol.","date":"2022","source":"Journal of fungi (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/35887459","citation_count":20,"is_preprint":false},{"pmid":"23554088","id":"PMC_23554088","title":"Intellectual disability and hemizygous GPD2 mutation.","date":"2013","source":"American journal of medical genetics. 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GPD2 (unlike GPD1) is specifically induced by anaerobic/anoxic conditions and is required for anaerobic growth, functioning as a redox sink for excess cytosolic NADH. Its anaerobic induction is independent of the HOG pathway that controls osmotic induction of GPD1.\",\n      \"method\": \"Gene deletion (gpd1Δ, gpd2Δ, double mutant), anaerobic growth assays, NADH accumulation measurements, acetaldehyde rescue experiment, CAT reporter gene transcriptional analysis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal genetic and biochemical methods, replicated across deletion backgrounds, mechanistic rescue with acetaldehyde\",\n      \"pmids\": [\"9171333\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"GPD2 encodes an sn-glycerol 3-phosphate dehydrogenase (NAD+) in S. cerevisiae sharing 69% identity with GPD1; GPD2 overexpression increases GPDH enzyme activity, and its promoter activity is decreased on non-fermentable carbon sources and is not induced by osmotic stress or heat shock.\",\n      \"method\": \"Gene cloning, disruption, overexpression, CAT reporter gene fusion transcriptional analysis, enzyme activity assay\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — direct enzyme activity assay combined with genetic disruption and promoter-reporter analysis in multiple conditions\",\n      \"pmids\": [\"7476212\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In LPS-activated macrophages, GPD2 (mitochondrial glycerol 3-phosphate dehydrogenase, a component of the glycerol phosphate shuttle) boosts glucose oxidation to fuel acetyl-CoA production, driving histone acetylation at inflammatory gene loci. During prolonged LPS exposure (tolerance), GPD2 coordinates a shutdown of oxidative metabolism, limiting acetyl-CoA availability for histone acetylation and suppressing inflammatory gene expression.\",\n      \"method\": \"GPD2 loss-of-function in macrophages, metabolic flux analysis, histone acetylation assays, gene expression analysis in LPS-stimulated and LPS-tolerant macrophages\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (metabolomics, histone acetylation, gene expression) with loss-of-function, published in high-impact journal with author correction confirming study validity\",\n      \"pmids\": [\"31384058\", \"31551573\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"GPD2 encodes mitochondrial glycerophosphate dehydrogenase (mGPDH), located on the outer surface of the inner mitochondrial membrane, catalyzing the unidirectional conversion of glycerol-3-phosphate (G3P) to dihydroxyacetone phosphate with concomitant reduction of enzyme-bound FAD. Haploinsufficiency of GPD2 leads to ~50% reduction in mGPDH transcript and activity in patient lymphoblastoid cell lines.\",\n      \"method\": \"FISH mapping of chromosomal breakpoint, molecular transcript quantification, functional enzyme activity assay in patient-derived lymphoblastoid cell lines\",\n      \"journal\": \"Human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct enzymatic activity measurement and transcript quantification in patient cells, single lab, no orthogonal structural validation\",\n      \"pmids\": [\"19011903\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"A hemizygous GPD2 missense mutation (p.Pro205Leu) combined with chromosomal deletion results in completely absent GPD2 enzymatic activity, while heterozygous carriers (mother, sister) have ~50% activity, establishing this residue as critical for enzymatic function.\",\n      \"method\": \"aCGH deletion mapping, Sanger sequencing, functional enzyme activity assay in patient-derived cells\",\n      \"journal\": \"American journal of medical genetics. Part A\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct functional enzyme assay with clear genotype-activity correlation; single lab, no structural validation\",\n      \"pmids\": [\"23554088\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Under ischemic conditions in cardiomyocytes, GPD2 is activated and converts glycerol-3-phosphate to dihydroxyacetone phosphate to facilitate ATP synthesis from glycerol. GPD2 deficiency exacerbates cardiac dysfunction after acute myocardial infarction, placing GPD2 downstream of LPL/AQP7-mediated glycerol supply in a cardioprotective pathway.\",\n      \"method\": \"GPD2-deficient mouse model, myocardial infarction (coronary ligation) model, cardiac function measurements, metabolic activity assays, cardiomyocyte-specific LPL and AQP7 deficiency models\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KO with defined cardiac phenotype and pathway placement, single lab\",\n      \"pmids\": [\"34807469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"GPD2 KO in cancer cells suppresses tumor growth not through its conventional bioenergetic role but by reducing dihydroxyacetone phosphate (DHAP) supply for ether lipid biosynthesis. Reduced ether lipid levels downregulate the Akt/mTORC1 pathway, and cell growth is rescued by supplementation with a DHAP precursor or ether lipids, defining a GPD2-ether lipid-Akt signaling axis.\",\n      \"method\": \"GPD2 knockout cells, in vivo tumor growth assay, multi-omics (metabolomics, transcriptomics, lipidomics), DHAP precursor and ether lipid supplementation rescue experiments\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (KO, metabolomics, lipidomics, pathway rescue), in vitro and in vivo validation, single lab\",\n      \"pmids\": [\"36632231\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Mitochondrial GCN5L1 directly binds GPD2 and modulates its enzymatic activity, regulating the glycerol phosphate shuttle and thereby controlling cytosolic redox state and hepatic gluconeogenesis from glycerol and lactate.\",\n      \"method\": \"GCN5L1 deletion cells/mice, gluconeogenesis assays, cytosolic redox measurement, co-immunoprecipitation of GCN5L1 and GPD2\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP binding plus functional activity assay; single lab, moderate mechanistic detail in abstract\",\n      \"pmids\": [\"35802941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"IMMP2L mitochondrial peptidase cleaves the mitochondrial transit peptide of GPD2; loss of IMMP2L reduces GPD2-mediated glycerol-3-phosphate-driven mitochondrial respiration (~20% decrease in females, ~7% in males) and alters the homodimeric structure of GPD2 within the inner mitochondrial membrane.\",\n      \"method\": \"Immp2l knockout mouse, substrate-specific mitochondrial respiration assays (G3P as substrate), AlphaFold2-Multimer structural prediction, EchoMRI, primary MEF cell lines\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct respiratory substrate assay in KO mouse tissues plus structural modeling; single lab, structural prediction is computational\",\n      \"pmids\": [\"38256063\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In CD133-positive HuH-7 hepatocarcinoma cells, GPD2 knockdown strongly reduces glycerol-3-phosphate-driven ATP synthesis (G3P-ATPase activity) and decreases anchorage-independent cell proliferation. p38 signaling downstream of CD133 regulates GPD2 expression and G3P-ATPase activity.\",\n      \"method\": \"GPD2 knockdown, G3P-driven ATP synthesis assay, p38 inhibitor treatment, anchorage-independent growth assay, CD133-positive cell sorting\",\n      \"journal\": \"Genes to cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD with direct enzymatic activity readout and defined cellular phenotype; single lab, pathway placement via inhibitor only\",\n      \"pmids\": [\"31887237\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Mitochondrial SPARC interacts with GPD2 (identified by co-immunoprecipitation), modulates GPD2 expression levels, and thereby regulates GPD2-mediated mitochondrial respiration to control migration and invasion of hepatocellular carcinoma cells.\",\n      \"method\": \"Cellular fractionation, immunofluorescence, Proteinase K protection assay for SPARC mitochondrial localization, co-immunoprecipitation (SPARC-GPD2), Seahorse XF Mito Stress Test, shRNA knockdown\",\n      \"journal\": \"Biochemical genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP plus functional mitochondrial respiration assay and phenotypic readout; single lab\",\n      \"pmids\": [\"38334876\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"GPD2 methylation at CpG site cg03230175 in its promoter region reduces GPD2 expression, suppresses mitochondrial energy metabolism, decreases ROS production, attenuates NF-κB activation, and reduces P2Y12 expression, ultimately inhibiting coagulation/platelet function. GPD2 enzyme inhibition prolongs clotting time in mice.\",\n      \"method\": \"850k methylation array, EWAS, CRISPR-dCas9-DNMT3A/Tet1CD epigenome editing, transcriptomic sequencing, cellular ROS/NF-κB/P2Y12 measurements, animal clotting assay\",\n      \"journal\": \"Cellular & molecular biology letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct epigenome editing with mechanistic pathway readouts plus in vivo validation; single lab\",\n      \"pmids\": [\"40682019\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Lactate secreted by cervical cancer cells upregulates H3K18 lactylation at the GPD2 locus in macrophages, driving GPD2 expression; GPD2 knockdown in macrophages reverses lactate-induced M2 polarization, establishing a lactate→histone lactylation→GPD2→M2 macrophage polarization axis.\",\n      \"method\": \"ChIP-seq for H3K18la, GPD2 knockdown in macrophages, conditioned medium experiments, M1/M2 marker measurement\",\n      \"journal\": \"DNA and cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP-seq plus KD rescue with defined functional readout; single lab\",\n      \"pmids\": [\"39504115\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"GPD2 binds directly to GPI (glucose-6-phosphate isomerase) as detected by microscale thermophoresis and protein interaction assays; esculetin binds GPD2 (and PGK2, GPI) and inhibits glycolytic flux as measured by lactate production and glucose consumption in HepG2 cells.\",\n      \"method\": \"Microscale thermophoresis (MST) binding assay, transcriptome/proteomics/reverse docking target identification, cellular glycolysis assay (lactate, glucose), animal xenograft\",\n      \"journal\": \"Frontiers in pharmacology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — MST binding and indirect cellular assay; single lab, limited mechanistic specificity for GPD2 alone\",\n      \"pmids\": [\"32292350\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"GPD2 knockdown in septic mice (CLP model) exacerbates lung injury by promoting ferroptosis; GPX4 activator (SeMet) reverses this, suggesting GPD2 suppresses ferroptosis through activation of the GPX4 pathway in the lung.\",\n      \"method\": \"AAV-mediated GPD2 knockdown, CLP sepsis mouse model, ferroptosis markers, GPX4 activator (SeMet) rescue, lung injury phenotype quantification\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KO with defined ferroptosis pathway rescue; single lab, pathway placement via pharmacological rescue only\",\n      \"pmids\": [\"41313944\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"GPD2 encodes mitochondrial glycerol-3-phosphate dehydrogenase (mGPDH), an FAD-linked enzyme located on the outer surface of the inner mitochondrial membrane that catalyzes the unidirectional oxidation of glycerol-3-phosphate (G3P) to dihydroxyacetone phosphate (DHAP), coupling cytosolic NADH reoxidation to mitochondrial electron transport via the glycerol phosphate shuttle; in macrophages this shuttle drives glucose oxidation and acetyl-CoA-dependent histone acetylation to regulate inflammatory gene expression, in cancer cells GPD2 supplies DHAP for ether lipid biosynthesis to sustain Akt/mTORC1 signaling and proliferation, in cardiomyocytes it supports ATP production from glycerol during ischemia, and its activity is regulated by IMMP2L-mediated transit peptide cleavage and by direct interaction with GCN5L1 and SPARC.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"GPD2 encodes a glycerol-3-phosphate dehydrogenase that catalyzes the unidirectional, FAD-coupled oxidation of glycerol-3-phosphate (G3P) to dihydroxyacetone phosphate (DHAP), serving as the mitochondrial arm of the glycerol phosphate shuttle that reoxidizes cytosolic reducing equivalents [#3]. In its yeast origins, the GPD2 isoform was defined genetically as an anaerobically induced, NAD+-dependent enzyme acting as a redox sink for excess cytosolic NADH, distinct in regulation from its paralog GPD1 [#0, #1]. Across mammalian systems, this single catalytic activity is repurposed for divergent physiological outputs: it boosts glucose oxidation to generate acetyl-CoA for histone acetylation at inflammatory loci in LPS-activated macrophages [#2], supplies DHAP for ether lipid biosynthesis that sustains Akt/mTORC1 signaling and tumor growth in cancer cells [#6], and supports G3P-driven ATP synthesis that is cardioprotective during ischemia downstream of LPL/AQP7-mediated glycerol supply [#5]. GPD2 enzymatic activity is set by its expression and by direct protein partners — the mitochondrial regulator GCN5L1 binds GPD2 to control the shuttle and hepatic gluconeogenesis [#7], SPARC binds GPD2 to tune respiration and HCC cell migration [#10] — and by IMMP2L-mediated cleavage of its mitochondrial transit peptide, which affects respiration and its homodimeric assembly in the inner membrane [#8]. Human GPD2 haploinsufficiency and a loss-of-function p.Pro205Leu mutation reduce or abolish mGPDH enzyme activity in patient cells [#3, #4].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Establishing that GPD2 encodes a functional NAD+-dependent glycerol-3-phosphate dehydrogenase defined the gene's core catalytic identity and showed its expression is carbon-source dependent but not stress-induced.\",\n      \"evidence\": \"Gene cloning, disruption, overexpression with enzyme activity assay and promoter-reporter analysis in S. cerevisiae\",\n      \"pmids\": [\"7476212\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve the physiological condition selecting for GPD2 over GPD1\", \"No mammalian context\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Genetic dissection answered why a second isoenzyme exists, showing GPD2 is specifically required under anaerobic conditions as a redox sink for excess cytosolic NADH, regulated independently of the osmotic HOG pathway.\",\n      \"evidence\": \"Deletion mutants, anaerobic growth assays, NADH measurements and acetaldehyde rescue in yeast\",\n      \"pmids\": [\"9171333\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Yeast NAD+-dependent activity differs from mammalian FAD-coupled mitochondrial enzyme\", \"Membrane topology not addressed\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Characterizing the human enzyme established GPD2 as mitochondrial glycerophosphate dehydrogenase on the inner membrane catalyzing unidirectional G3P-to-DHAP conversion, and linked gene dosage to enzyme activity in patients.\",\n      \"evidence\": \"FISH breakpoint mapping, transcript quantification and enzyme activity assay in patient lymphoblastoid lines\",\n      \"pmids\": [\"19011903\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural validation\", \"Single lab\", \"Disease causality from haploinsufficiency alone not firmly established\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"A genotype-activity correlation identified residue Pro205 as critical, showing combined hemizygous missense plus deletion abolishes activity while heterozygotes retain ~50%.\",\n      \"evidence\": \"aCGH, Sanger sequencing and enzyme activity assays in patient-derived cells\",\n      \"pmids\": [\"23554088\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural mechanism for how Pro205Leu impairs catalysis\", \"Single family\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Connecting GPD2 flux to chromatin showed the shuttle drives glucose oxidation and acetyl-CoA-dependent histone acetylation to set inflammatory gene expression in macrophages and to enforce LPS tolerance.\",\n      \"evidence\": \"Macrophage loss-of-function, metabolic flux, histone acetylation and gene expression analyses\",\n      \"pmids\": [\"31384058\", \"31551573\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct enzymatic coupling to specific histone marks not biochemically reconstituted\", \"Mechanism of tolerance-phase shutdown unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Cancer studies tied GPD2-driven G3P-ATP synthesis to malignant phenotype and placed GPD2 expression downstream of CD133/p38 signaling.\",\n      \"evidence\": \"GPD2 knockdown, G3P-ATP synthesis assay, p38 inhibition and anchorage-independent growth in CD133+ hepatocarcinoma cells\",\n      \"pmids\": [\"31887237\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Pathway placement relies on inhibitor only\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"An in vivo KO defined a cardioprotective role, showing GPD2 enables ATP synthesis from glycerol during ischemia downstream of LPL/AQP7 glycerol supply.\",\n      \"evidence\": \"GPD2-deficient mouse, myocardial infarction model, cardiac function and metabolic assays with LPL/AQP7 KO\",\n      \"pmids\": [\"34807469\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Mechanism of GPD2 activation under ischemia not detailed\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identifying GCN5L1 as a direct binding partner revealed protein-level regulation of GPD2 activity that controls cytosolic redox and hepatic gluconeogenesis.\",\n      \"evidence\": \"Co-IP, GCN5L1 deletion cells/mice, gluconeogenesis and cytosolic redox assays\",\n      \"pmids\": [\"35802941\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No reciprocal validation or binding interface mapped\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Multi-omics with rescue redefined GPD2's oncogenic role as biosynthetic rather than purely bioenergetic, establishing a GPD2-DHAP-ether lipid-Akt/mTORC1 axis.\",\n      \"evidence\": \"GPD2 KO cells, in vivo tumor growth, metabolomics/lipidomics, DHAP precursor and ether lipid rescue\",\n      \"pmids\": [\"36632231\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct enzyme-to-ether-lipid flux not measured in real time\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Several findings established additional layers of GPD2 regulation: IMMP2L cleaves its transit peptide affecting respiration and dimer structure, SPARC binds and tunes GPD2-dependent respiration in HCC, and lactate-induced H3K18 lactylation drives GPD2 to promote M2 macrophage polarization.\",\n      \"evidence\": \"Immp2l KO mice with substrate respiration and AlphaFold2 modeling; SPARC-GPD2 co-IP with Seahorse assays; H3K18la ChIP-seq with GPD2 knockdown\",\n      \"pmids\": [\"38256063\", \"38334876\", \"39504115\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural effect of IMMP2L cleavage is computational\", \"SPARC and GCN5L1 binding interfaces unmapped\", \"Lactylation-to-transcription mechanism incomplete\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Newer studies extended GPD2 to platelet function via promoter methylation suppressing energy metabolism/NF-kB/P2Y12, and to anti-ferroptosis protection in sepsis-induced lung injury via the GPX4 pathway.\",\n      \"evidence\": \"CRISPR-dCas9 epigenome editing with clotting assays; AAV knockdown in CLP sepsis with GPX4 activator rescue\",\n      \"pmids\": [\"40682019\", \"41313944\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"GPX4-GPD2 link rests on pharmacological rescue only\", \"Mechanism connecting enzymatic activity to ferroptosis unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single G3P-DHAP catalytic activity is mechanistically routed to such divergent outputs (chromatin acetylation, ether lipid synthesis, redox, ferroptosis) and how its partner interactions structurally regulate catalysis remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No experimental atomic structure of human GPD2\", \"Binding interfaces for GCN5L1/SPARC undefined\", \"Determinants selecting bioenergetic vs biosynthetic flux unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016491\", \"supporting_discovery_ids\": [0, 1, 3, 4]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [3, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [3, 8, 10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [2, 5, 6]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 12]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"GCN5L1\", \"SPARC\", \"IMMP2L\", \"GPI\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}