{"gene":"CEPT1","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2002,"finding":"CEPT1 is a dual-specificity enzyme that catalyzes the transfer of a phosphobase from CDP-choline or CDP-ethanolamine to diacylglycerol (DAG) to produce phosphatidylcholine (PC) and phosphatidylethanolamine (PE), respectively. Mixed micellar kinetic analysis established apparent Km values of 36 µM for CDP-choline and 98 µM for CDP-ethanolamine, with preferred DAG substrates being di-18:1, di-16:1, and 16:0/18:1 DAG. Both cholinephosphotransferase and ethanolaminephosphotransferase activities showed product activation at 5 mol%, implying specific lipid activation binding sites on CEPT1. The enzyme was inhibited by protein kinase C inhibitor chelerythrine and DAG kinase inhibitor R59949 (IC50 ~40 µM each).","method":"Mixed micellar in vitro enzyme assay with heterologous expression system lacking endogenous activity; kinetic parameter determination; inhibitor studies","journal":"Lipids","confidence":"High","confidence_rationale":"Tier 1 / Strong — rigorous in vitro reconstitution with defined substrates, Km/Vmax measurements, and inhibitor profiling in an expression system devoid of endogenous activity","pmids":["12216837"],"is_preprint":false},{"year":2020,"finding":"CEPT1 localizes to the endoplasmic reticulum (ER), whereas EPT1 localizes to the Golgi apparatus, as established by immunohistochemical analysis in HEK293 cells. In vitro enzymatic analysis showed CEPT1 greatly prefers DAG 16:0-18:1 over other lipid acceptors, while EPT1 prefers alkyl-acyl-glycerol substrates. Metabolic labeling in CEPT1-deficient cells confirmed CEPT1 is important for PE synthesis from shorter-chain fatty acids (32:2, 32:1, 34:2, 34:1 species), whereas EPT1 contributes more to plasmalogen PE and longer-chain PUFA-PE species.","method":"Immunohistochemistry (subcellular localization); CRISPR-generated knockout cells; radio- and deuterium-labeled ethanolamine metabolic labeling; in vitro enzyme assay with defined substrates; LC-MS lipidomics","journal":"Journal of lipid research","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (localization, KO cells, in vitro assay, MS lipidomics) in a single focused study","pmids":["32576654"],"is_preprint":false},{"year":2021,"finding":"CEPT1 localizes to the endoplasmic reticulum (ER), while CPT1 (CHPT1) localizes to the trans-Golgi network. CEPT1 accounts for the majority of choline phospholipid biosynthesis activity, with loss of CEPT1 dramatically decreasing choline PL biosynthesis. Both CPT1 and CEPT1 have similar PC molecular species preferences, but CPT1 has higher preference for 1-alkyl-2-acyl-sn-glycerophosphocholine with PUFA. The specific enzymatic activity of CEPT1 is much higher than that of CPT1.","method":"Immunohistochemistry (subcellular localization); CRISPR-generated KO HEK293 cells; radiolabeled choline metabolic labeling; quantitative PCR and enzyme reintroduction; LC-MS/MS of deuterium-labeled lipid species","journal":"Journal of lipid research","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (localization, KO rescue, metabolic labeling, MS lipidomics) in a focused study","pmids":["34331935"],"is_preprint":false},{"year":2023,"finding":"CEPT1 localizes to the ER and is in close proximity to cytoplasmic lipid droplets (LDs). CEPT1 KO in U2OS cells caused a 50% reduction in PC synthesis and 80% reduction in PE synthesis, induced posttranscriptional upregulation of CCTα protein, caused CCTα dephosphorylation and constitutive localization on the inner nuclear membrane and nucleoplasmic reticulum (activated state), accumulation of small cytoplasmic LDs, and increased nuclear LDs enriched in CCTα. Restoring PC by incubating CEPT1-KO cells with PC liposomes prevented the activated CCTα phenotype, confirming end-product inhibition. CHPT1 KO had no effect on CCTα regulation or LD biogenesis, establishing that only ER-synthesized PC by CEPT1 regulates CCTα and LD biogenesis.","method":"CRISPR KO in U2OS cells; [14C]-choline metabolic labeling; proximity ligation/imaging for LD association; PC liposome rescue; immunofluorescence for CCTα localization; fluorescence microscopy for LD quantification","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — CRISPR KO with metabolic labeling, rescue experiments, and multiple orthogonal readouts establishing ER-specific PC function in CCTα regulation and LD biogenesis","pmids":["36871755"],"is_preprint":false},{"year":2020,"finding":"CEPT1 is essential for endothelial cell (EC) function; conditional EC-specific deletion of Cept1 decreased EC proliferation, migration, and tubule formation in vitro. In vivo, Cept1 EC-knockout mice had reduced perfusion and angiogenesis in ischemic hind limbs. Cept1 siRNA knockdown in ECs decreased PPARα phosphorylation (Ser12), which was rescued by fenofibrate (PPARα agonist) but not by exogenous PC 16:0/18:1. In Cept1 EC-KO mice lacking Pparα (Cept1Lp/LpCre+ Ppara−/−), fenofibrate failed to restore hind-paw perfusion recovery, placing CEPT1 upstream of PPARα in ischemic angiogenesis.","method":"Conditional EC-specific Cept1 knockout (VE-cadherin-CreERT2); in vitro EC functional assays (proliferation, migration, tubule formation); hindlimb ischemia in vivo model; siRNA knockdown; genetic epistasis (double KO with Ppara); fenofibrate rescue","journal":"Diabetes","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO with multiple in vitro and in vivo readouts, genetic epistasis with Ppara double KO, and rescue experiments","pmids":["33214136"],"is_preprint":false},{"year":2024,"finding":"CEPT1 was identified as an LPCAT3-interacting protein via proteomic analysis, and CEPT1 regulates LPCAT3 protein stability. Beyond its role in phospholipid synthesis, CEPT1 suppresses ferroptosis, potentially by interacting with phospholipases to break down pro-ferroptotic PUFA-containing phospholipids.","method":"Proteomic protein interaction landscape analysis; co-immunoprecipitation (LPCAT3 interaction); ferroptosis assays in cells with CEPT1 modulation","journal":"Protein & cell","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — proteomic interaction screen with some functional follow-up, but the phospholipase interaction and PUFA-PL degradation mechanism are not fully resolved from the abstract","pmids":["38430542"],"is_preprint":false},{"year":2025,"finding":"CEPT1 overexpression in endothelial cells increased PPARα, ACOX1, VEGF-A, and VEGFR2 expression and promoted EC migration, tubule formation, and proliferation. Pharmacological inhibition of PPARα (GW6471), VEGFR2 (ZM323881), Akt (LY294002), and eNOS (L-NAME) each abrogated CEPT1-induced EC migration, placing CEPT1 upstream of a PPARα→VEGF-A→VEGFR2→p-Akt/p-eNOS signaling axis in angiogenesis.","method":"Conditional EC-specific Cept1 overexpression mouse model; single-cell RNA sequencing; in vitro EC functional assays; pharmacological inhibitor studies; hindlimb ischemia and aortic ring sprouting assays","journal":"Arteriosclerosis, thrombosis, and vascular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain-of-function in vivo model with scRNA-seq and inhibitor pathway dissection, single lab, extends prior loss-of-function findings","pmids":["41263082"],"is_preprint":false},{"year":2026,"finding":"FOXA1 is a direct transcriptional activator of CEPT1 in airway epithelium, as identified by integrative data mining and mechanistic follow-up. CEPT1 deficiency causes PC/PE reduction and phospholipid imbalance, which activates all three ER stress pathways (IRE1α, PERK, ATF6), disturbs ER Ca2+ stores, and drives mitochondrial Ca2+ overload and oxidative stress. In vivo CEPT1 overexpression alleviates airway inflammation and mucus hypersecretion in asthma models.","method":"FOXA1 transcriptional regulation studies; CEPT1 KD/OE in airway epithelial cells; ER stress pathway activation assays; Ca2+ imaging; mitochondrial ROS assays; in vivo mouse asthma model with CEPT1 overexpression; polyenylphosphatidylcholine rescue","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function and gain-of-function with multiple pathway readouts and rescue, single lab, abstract lacks full methodological detail","pmids":["42176270"],"is_preprint":false},{"year":2026,"finding":"CTPS1 upregulates CEPT1 expression by increasing CTP availability (substrate for CDP-choline/CDP-ethanolamine pathways), thereby reprogramming glycerophospholipid metabolism. CEPT1-synthesized glycerophospholipids maintain mitochondrial homeostasis and promote BNIP3-mediated mitophagy in DLBCL cells.","method":"scRNA-seq pathway analysis; CTPS1 KD/OE in DLBCL cells; CEPT1 expression measurement upon CTPS1 modulation; mitophagy assays; BNIP3 functional studies","journal":"Redox biology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — mechanistic claims are primarily from scRNA-seq and knockdown with limited biochemical validation described in the abstract","pmids":["41865720"],"is_preprint":false},{"year":2025,"finding":"Endothelial CEPT1 silencing suppresses MTTP (microsomal triglyceride transfer protein) expression and activity in co-cultured hepatocytes via a paracrine mechanism involving PPARα signaling, and this effect is rescued by fenofibrate treatment. Endothelial-specific Cept1 knockdown in mice decreased serum triglyceride and cholesterol levels and attenuated aortic atherosclerosis.","method":"In vitro co-culture of endothelial cells and hepatocytes with CEPT1 silencing; MTTP activity assay; endothelial-specific Cept1 KD mouse model; serum lipid analysis; aortic histology; fenofibrate rescue","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — preprint, single lab, paracrine mechanism inferred from co-culture and in vivo KD without full biochemical reconstitution","pmids":[],"is_preprint":true}],"current_model":"CEPT1 is a dual-specificity ER-resident enzyme that catalyzes the final steps of PC and PE biosynthesis via the Kennedy pathway by transferring phosphocholine or phosphoethanolamine from CDP-choline or CDP-ethanolamine to diacylglycerol; it preferentially uses unsaturated DAG substrates, its ER-synthesized products feedback-inhibit CCTα and regulate lipid droplet biogenesis, it functions upstream of PPARα in endothelial angiogenic signaling, and it also suppresses ferroptosis through interaction with LPCAT3 and phospholipases that degrade pro-ferroptotic PUFA-phospholipids."},"narrative":{"mechanistic_narrative":"CEPT1 is a dual-specificity, ER-resident enzyme that catalyzes the final committed step of the Kennedy pathway, transferring a phosphobase from CDP-choline or CDP-ethanolamine to diacylglycerol to generate phosphatidylcholine (PC) and phosphatidylethanolamine (PE) [PMID:12216837]. It prefers unsaturated DAG acceptors and is subject to product activation, and it accounts for the majority of cellular choline-phospholipid biosynthesis [PMID:12216837, PMID:34331935]. Its ER localization is functionally distinct from the Golgi-resident related transferases EPT1 and CHPT1, which favor alkyl-acyl and plasmalogen/PUFA substrates, and only ER-synthesized PC made by CEPT1 feedback-regulates CCTα — loss of CEPT1 drives posttranscriptional CCTα upregulation, dephosphorylation, and constitutive nuclear-membrane localization together with aberrant lipid droplet accumulation, all reversible by PC repletion [PMID:32576654, PMID:34331935, PMID:36871755]. Beyond bulk phospholipid supply, CEPT1 is essential for endothelial proliferation, migration, and angiogenesis in vivo, acting upstream of a PPARα→VEGF-A→VEGFR2→Akt/eNOS signaling axis [PMID:33214136, PMID:41263082]. CEPT1 also interacts with and stabilizes LPCAT3 and thereby suppresses ferroptosis [PMID:38430542]. No high-confidence structural model of the enzyme has been characterized in the available corpus.","teleology":[{"year":2002,"claim":"Established CEPT1 as a single dual-specificity enzyme producing both PC and PE, defining its core catalytic identity and substrate preferences.","evidence":"Mixed-micellar in vitro enzyme assay in a heterologous system lacking endogenous activity, with Km determination and inhibitor profiling","pmids":["12216837"],"confidence":"High","gaps":["No structural basis for dual specificity or the inferred lipid activation sites","In vitro kinetics do not establish in-cell flux contribution"]},{"year":2020,"claim":"Resolved the division of labor among phosphobase transferases by showing CEPT1 is ER-localized and drives PE synthesis from shorter-chain species, distinct from Golgi-resident EPT1.","evidence":"Immunohistochemistry, CRISPR knockout cells, metabolic labeling, in vitro assay, and LC-MS lipidomics in HEK293","pmids":["32576654"],"confidence":"High","gaps":["Does not address regulation of CEPT1 substrate channeling","Localization determinants not mapped"]},{"year":2021,"claim":"Quantified CEPT1 as the dominant contributor to choline phospholipid biosynthesis relative to Golgi-resident CHPT1/CPT1.","evidence":"CRISPR KO/rescue HEK293 cells, radiolabeled choline labeling, qPCR, and deuterium-labeled LC-MS/MS","pmids":["34331935"],"confidence":"High","gaps":["Tissue-specific relative contributions not established","Does not address downstream signaling consequences"]},{"year":2023,"claim":"Demonstrated that only ER-synthesized PC made by CEPT1 feedback-regulates CCTα activation state and lipid droplet biogenesis, linking the enzyme to lipid homeostatic control.","evidence":"CRISPR KO in U2OS, [14C]-choline labeling, CCTα localization imaging, PC liposome rescue, and LD quantification","pmids":["36871755"],"confidence":"High","gaps":["Molecular mechanism of how ER-PC pool is sensed by CCTα not resolved","Nuclear LD function not defined"]},{"year":2020,"claim":"Placed CEPT1 upstream of PPARα in endothelial angiogenic signaling through genetic epistasis, extending its role from lipid metabolism to vascular function.","evidence":"Conditional EC-specific Cept1 knockout, hindlimb ischemia model, Cept1/Ppara double KO, siRNA knockdown, and fenofibrate rescue","pmids":["33214136"],"confidence":"High","gaps":["How PC/PE metabolism mechanistically activates PPARα not established","Exogenous PC failed to rescue, leaving the lipid signal undefined"]},{"year":2024,"claim":"Identified a phospholipid-synthesis-independent role: CEPT1 binds and stabilizes LPCAT3 and suppresses ferroptosis.","evidence":"Proteomic interaction screen, co-immunoprecipitation, and ferroptosis assays with CEPT1 modulation","pmids":["38430542"],"confidence":"Medium","gaps":["Phospholipase interactions and PUFA-phospholipid degradation mechanism not biochemically resolved","Direct vs indirect contribution to ferroptosis not separated from synthesis function"]},{"year":2025,"claim":"Gain-of-function established CEPT1 as a positive driver of a PPARα→VEGF-A→VEGFR2→Akt/eNOS angiogenic cascade.","evidence":"EC-specific Cept1 overexpression mouse, scRNA-seq, inhibitor pathway dissection, and sprouting/ischemia assays","pmids":["41263082"],"confidence":"Medium","gaps":["Single-lab gain-of-function correlation; direct molecular link from CEPT1 to PPARα still missing","Inhibitor epistasis does not prove a linear pathway"]},{"year":2026,"claim":"Connected CEPT1 deficiency to phospholipid imbalance that triggers ER stress and mitochondrial Ca2+/oxidative stress, and identified FOXA1 as a direct transcriptional activator in airway epithelium.","evidence":"FOXA1 transcriptional studies, CEPT1 KD/OE in airway epithelial cells, ER stress and Ca2+/ROS assays, asthma mouse model with rescue","pmids":["42176270"],"confidence":"Medium","gaps":["Causal chain from phospholipid imbalance to ER stress not dissected step-by-step","Tissue specificity of FOXA1 regulation not generalized"]},{"year":2026,"claim":"Linked CEPT1 to nucleotide-driven metabolic reprogramming, with CTPS1-supplied CTP boosting CEPT1 expression to support mitochondrial homeostasis and BNIP3 mitophagy in lymphoma cells.","evidence":"scRNA-seq, CTPS1 KD/OE in DLBCL cells, CEPT1 expression measurement, and mitophagy/BNIP3 assays","pmids":["41865720"],"confidence":"Low","gaps":["Primarily scRNA-seq and knockdown with limited biochemical validation","Direct effect of CEPT1 lipids on mitophagy not reconstituted"]},{"year":null,"claim":"How CEPT1-derived phospholipid pools are mechanistically transduced into PPARα activation and the structural basis of its dual catalytic specificity remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the enzyme","Identity of the lipid signal coupling CEPT1 to PPARα unknown","Phospholipase partners in ferroptosis suppression unconfirmed"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[5]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[1,2,3]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,1,2]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4,6]}],"complexes":[],"partners":["LPCAT3","CCTALPHA"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9Y6K0","full_name":"Choline/ethanolaminephosphotransferase 1","aliases":["1-alkenyl-2-acylglycerol choline phosphotransferase"],"length_aa":416,"mass_kda":46.6,"function":"Catalyzes both phosphatidylcholine and phosphatidylethanolamine biosynthesis from CDP-choline and CDP-ethanolamine, respectively (PubMed:10191259, PubMed:10893425, PubMed:12216837, PubMed:37137909). Involved in protein-dependent process of phospholipid transport to distribute phosphatidyl choline to the lumenal surface (PubMed:10191259, PubMed:10893425, PubMed:12216837). Has a higher cholinephosphotransferase activity than ethanolaminephosphotransferase activity (PubMed:10191259, PubMed:12216837)","subcellular_location":"Endoplasmic reticulum membrane; Nucleus membrane","url":"https://www.uniprot.org/uniprotkb/Q9Y6K0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CEPT1","classification":"Not Classified","n_dependent_lines":315,"n_total_lines":1208,"dependency_fraction":0.26076158940397354},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000134255","cell_line_id":"CID000346","localizations":[{"compartment":"er","grade":3},{"compartment":"vesicles","grade":3}],"interactors":[{"gene":"CAPZB","stoichiometry":0.2},{"gene":"DCP1B","stoichiometry":0.2},{"gene":"PGRMC1","stoichiometry":0.2},{"gene":"CCDC47","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000346","total_profiled":1310},"omim":[{"mim_id":"616751","title":"CHOLINE/ETHANOLAMINE PHOSPHOTRANSFERASE 1; CEPT1","url":"https://www.omim.org/entry/616751"}],"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/CEPT1"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q9Y6K0","domains":[{"cath_id":"1.20.120.1760","chopping":"62-398","consensus_level":"medium","plddt":96.1241,"start":62,"end":398}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y6K0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y6K0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y6K0-F1-predicted_aligned_error_v6.png","plddt_mean":88.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CEPT1","jax_strain_url":"https://www.jax.org/strain/search?query=CEPT1"},"sequence":{"accession":"Q9Y6K0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y6K0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y6K0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y6K0"}},"corpus_meta":[{"pmid":"12216837","id":"PMC_12216837","title":"PC and PE synthesis: mixed micellar analysis of the cholinephosphotransferase and ethanolaminephosphotransferase activities of human choline/ethanolamine phosphotransferase 1 (CEPT1).","date":"2002","source":"Lipids","url":"https://pubmed.ncbi.nlm.nih.gov/12216837","citation_count":47,"is_preprint":false},{"pmid":"32576654","id":"PMC_32576654","title":"Locations and contributions of the phosphotransferases EPT1 and CEPT1 to the biosynthesis of ethanolamine phospholipids.","date":"2020","source":"Journal of lipid research","url":"https://pubmed.ncbi.nlm.nih.gov/32576654","citation_count":40,"is_preprint":false},{"pmid":"34331935","id":"PMC_34331935","title":"Differential contributions of choline phosphotransferases CPT1 and CEPT1 to the biosynthesis of choline phospholipids.","date":"2021","source":"Journal of lipid research","url":"https://pubmed.ncbi.nlm.nih.gov/34331935","citation_count":34,"is_preprint":false},{"pmid":"38430542","id":"PMC_38430542","title":"Proteomic analysis of ferroptosis pathways reveals a role of CEPT1 in suppressing ferroptosis.","date":"2024","source":"Protein & cell","url":"https://pubmed.ncbi.nlm.nih.gov/38430542","citation_count":28,"is_preprint":false},{"pmid":"36871755","id":"PMC_36871755","title":"Differential contributions of phosphotransferases CEPT1 and CHPT1 to phosphatidylcholine homeostasis and lipid droplet biogenesis.","date":"2023","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/36871755","citation_count":26,"is_preprint":false},{"pmid":"33450726","id":"PMC_33450726","title":"Localized increases in CEPT1 and ATGL elevate plasmalogen phosphatidylcholines in HDLs contributing to atheroprotective lipid profiles in hyperglycemic GCK-MODY.","date":"2021","source":"Redox biology","url":"https://pubmed.ncbi.nlm.nih.gov/33450726","citation_count":20,"is_preprint":false},{"pmid":"33214136","id":"PMC_33214136","title":"CEPT1-Mediated Phospholipogenesis Regulates Endothelial Cell Function and Ischemia-Induced Angiogenesis Through PPARα.","date":"2020","source":"Diabetes","url":"https://pubmed.ncbi.nlm.nih.gov/33214136","citation_count":16,"is_preprint":false},{"pmid":"41218845","id":"PMC_41218845","title":"Imperatorin ameliorates metabolic dysfunction-associated fatty liver disease through modulating Suv39h1/Fabps/Cept1 signalling pathway.","date":"2025","source":"British journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/41218845","citation_count":2,"is_preprint":false},{"pmid":"41263082","id":"PMC_41263082","title":"Endothelial CEPT1 Promotes Angiogenesis Through PPARα and VEGF-A Signaling.","date":"2025","source":"Arteriosclerosis, thrombosis, and vascular biology","url":"https://pubmed.ncbi.nlm.nih.gov/41263082","citation_count":0,"is_preprint":false},{"pmid":"41865720","id":"PMC_41865720","title":"CTPS1 modulates mitophagy to propel diffuse large B-cell lymphoma via reshaping CEPT1-mediated phospholipid metabolism.","date":"2026","source":"Redox biology","url":"https://pubmed.ncbi.nlm.nih.gov/41865720","citation_count":0,"is_preprint":false},{"pmid":"42176270","id":"PMC_42176270","title":"FOXA1-mediated CEPT1 deficiency in airway epithelium drives asthma via an ER stress-mitochondrial dysfunction axis.","date":"2026","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/42176270","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.09.21.677657","title":"Endothelial CEPT1 Regulates Hepatic MTTP-Mediated Lipid Metabolism and Impacts Aortic Atherosclerosis","date":"2025-09-21","source":"bioRxiv","url":"https://doi.org/10.1101/2025.09.21.677657","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.03.11.642511","title":"Endothelial  <i>Cept1</i>  Promotes Post-Ischemic Angiogenesis in a  <i>Pparα</i>  -Dependent Fashion","date":"2025-03-14","source":"bioRxiv","url":"https://doi.org/10.1101/2025.03.11.642511","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.07.17.665462","title":"MTARC1 Regulates Lipid Droplet Degradation via Phospholipid Remodeling in Metabolic Fatty Liver Disease","date":"2025-07-21","source":"bioRxiv","url":"https://doi.org/10.1101/2025.07.17.665462","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10997,"output_tokens":3495,"usd":0.042708,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11161,"output_tokens":3194,"usd":0.067827,"stage2_stop_reason":"end_turn"},"total_usd":0.110535,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"CEPT1 is a dual-specificity enzyme that catalyzes the transfer of a phosphobase from CDP-choline or CDP-ethanolamine to diacylglycerol (DAG) to produce phosphatidylcholine (PC) and phosphatidylethanolamine (PE), respectively. Mixed micellar kinetic analysis established apparent Km values of 36 µM for CDP-choline and 98 µM for CDP-ethanolamine, with preferred DAG substrates being di-18:1, di-16:1, and 16:0/18:1 DAG. Both cholinephosphotransferase and ethanolaminephosphotransferase activities showed product activation at 5 mol%, implying specific lipid activation binding sites on CEPT1. The enzyme was inhibited by protein kinase C inhibitor chelerythrine and DAG kinase inhibitor R59949 (IC50 ~40 µM each).\",\n      \"method\": \"Mixed micellar in vitro enzyme assay with heterologous expression system lacking endogenous activity; kinetic parameter determination; inhibitor studies\",\n      \"journal\": \"Lipids\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — rigorous in vitro reconstitution with defined substrates, Km/Vmax measurements, and inhibitor profiling in an expression system devoid of endogenous activity\",\n      \"pmids\": [\"12216837\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CEPT1 localizes to the endoplasmic reticulum (ER), whereas EPT1 localizes to the Golgi apparatus, as established by immunohistochemical analysis in HEK293 cells. In vitro enzymatic analysis showed CEPT1 greatly prefers DAG 16:0-18:1 over other lipid acceptors, while EPT1 prefers alkyl-acyl-glycerol substrates. Metabolic labeling in CEPT1-deficient cells confirmed CEPT1 is important for PE synthesis from shorter-chain fatty acids (32:2, 32:1, 34:2, 34:1 species), whereas EPT1 contributes more to plasmalogen PE and longer-chain PUFA-PE species.\",\n      \"method\": \"Immunohistochemistry (subcellular localization); CRISPR-generated knockout cells; radio- and deuterium-labeled ethanolamine metabolic labeling; in vitro enzyme assay with defined substrates; LC-MS lipidomics\",\n      \"journal\": \"Journal of lipid research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (localization, KO cells, in vitro assay, MS lipidomics) in a single focused study\",\n      \"pmids\": [\"32576654\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CEPT1 localizes to the endoplasmic reticulum (ER), while CPT1 (CHPT1) localizes to the trans-Golgi network. CEPT1 accounts for the majority of choline phospholipid biosynthesis activity, with loss of CEPT1 dramatically decreasing choline PL biosynthesis. Both CPT1 and CEPT1 have similar PC molecular species preferences, but CPT1 has higher preference for 1-alkyl-2-acyl-sn-glycerophosphocholine with PUFA. The specific enzymatic activity of CEPT1 is much higher than that of CPT1.\",\n      \"method\": \"Immunohistochemistry (subcellular localization); CRISPR-generated KO HEK293 cells; radiolabeled choline metabolic labeling; quantitative PCR and enzyme reintroduction; LC-MS/MS of deuterium-labeled lipid species\",\n      \"journal\": \"Journal of lipid research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (localization, KO rescue, metabolic labeling, MS lipidomics) in a focused study\",\n      \"pmids\": [\"34331935\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CEPT1 localizes to the ER and is in close proximity to cytoplasmic lipid droplets (LDs). CEPT1 KO in U2OS cells caused a 50% reduction in PC synthesis and 80% reduction in PE synthesis, induced posttranscriptional upregulation of CCTα protein, caused CCTα dephosphorylation and constitutive localization on the inner nuclear membrane and nucleoplasmic reticulum (activated state), accumulation of small cytoplasmic LDs, and increased nuclear LDs enriched in CCTα. Restoring PC by incubating CEPT1-KO cells with PC liposomes prevented the activated CCTα phenotype, confirming end-product inhibition. CHPT1 KO had no effect on CCTα regulation or LD biogenesis, establishing that only ER-synthesized PC by CEPT1 regulates CCTα and LD biogenesis.\",\n      \"method\": \"CRISPR KO in U2OS cells; [14C]-choline metabolic labeling; proximity ligation/imaging for LD association; PC liposome rescue; immunofluorescence for CCTα localization; fluorescence microscopy for LD quantification\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — CRISPR KO with metabolic labeling, rescue experiments, and multiple orthogonal readouts establishing ER-specific PC function in CCTα regulation and LD biogenesis\",\n      \"pmids\": [\"36871755\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CEPT1 is essential for endothelial cell (EC) function; conditional EC-specific deletion of Cept1 decreased EC proliferation, migration, and tubule formation in vitro. In vivo, Cept1 EC-knockout mice had reduced perfusion and angiogenesis in ischemic hind limbs. Cept1 siRNA knockdown in ECs decreased PPARα phosphorylation (Ser12), which was rescued by fenofibrate (PPARα agonist) but not by exogenous PC 16:0/18:1. In Cept1 EC-KO mice lacking Pparα (Cept1Lp/LpCre+ Ppara−/−), fenofibrate failed to restore hind-paw perfusion recovery, placing CEPT1 upstream of PPARα in ischemic angiogenesis.\",\n      \"method\": \"Conditional EC-specific Cept1 knockout (VE-cadherin-CreERT2); in vitro EC functional assays (proliferation, migration, tubule formation); hindlimb ischemia in vivo model; siRNA knockdown; genetic epistasis (double KO with Ppara); fenofibrate rescue\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO with multiple in vitro and in vivo readouts, genetic epistasis with Ppara double KO, and rescue experiments\",\n      \"pmids\": [\"33214136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CEPT1 was identified as an LPCAT3-interacting protein via proteomic analysis, and CEPT1 regulates LPCAT3 protein stability. Beyond its role in phospholipid synthesis, CEPT1 suppresses ferroptosis, potentially by interacting with phospholipases to break down pro-ferroptotic PUFA-containing phospholipids.\",\n      \"method\": \"Proteomic protein interaction landscape analysis; co-immunoprecipitation (LPCAT3 interaction); ferroptosis assays in cells with CEPT1 modulation\",\n      \"journal\": \"Protein & cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — proteomic interaction screen with some functional follow-up, but the phospholipase interaction and PUFA-PL degradation mechanism are not fully resolved from the abstract\",\n      \"pmids\": [\"38430542\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CEPT1 overexpression in endothelial cells increased PPARα, ACOX1, VEGF-A, and VEGFR2 expression and promoted EC migration, tubule formation, and proliferation. Pharmacological inhibition of PPARα (GW6471), VEGFR2 (ZM323881), Akt (LY294002), and eNOS (L-NAME) each abrogated CEPT1-induced EC migration, placing CEPT1 upstream of a PPARα→VEGF-A→VEGFR2→p-Akt/p-eNOS signaling axis in angiogenesis.\",\n      \"method\": \"Conditional EC-specific Cept1 overexpression mouse model; single-cell RNA sequencing; in vitro EC functional assays; pharmacological inhibitor studies; hindlimb ischemia and aortic ring sprouting assays\",\n      \"journal\": \"Arteriosclerosis, thrombosis, and vascular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain-of-function in vivo model with scRNA-seq and inhibitor pathway dissection, single lab, extends prior loss-of-function findings\",\n      \"pmids\": [\"41263082\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"FOXA1 is a direct transcriptional activator of CEPT1 in airway epithelium, as identified by integrative data mining and mechanistic follow-up. CEPT1 deficiency causes PC/PE reduction and phospholipid imbalance, which activates all three ER stress pathways (IRE1α, PERK, ATF6), disturbs ER Ca2+ stores, and drives mitochondrial Ca2+ overload and oxidative stress. In vivo CEPT1 overexpression alleviates airway inflammation and mucus hypersecretion in asthma models.\",\n      \"method\": \"FOXA1 transcriptional regulation studies; CEPT1 KD/OE in airway epithelial cells; ER stress pathway activation assays; Ca2+ imaging; mitochondrial ROS assays; in vivo mouse asthma model with CEPT1 overexpression; polyenylphosphatidylcholine rescue\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function and gain-of-function with multiple pathway readouts and rescue, single lab, abstract lacks full methodological detail\",\n      \"pmids\": [\"42176270\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"CTPS1 upregulates CEPT1 expression by increasing CTP availability (substrate for CDP-choline/CDP-ethanolamine pathways), thereby reprogramming glycerophospholipid metabolism. CEPT1-synthesized glycerophospholipids maintain mitochondrial homeostasis and promote BNIP3-mediated mitophagy in DLBCL cells.\",\n      \"method\": \"scRNA-seq pathway analysis; CTPS1 KD/OE in DLBCL cells; CEPT1 expression measurement upon CTPS1 modulation; mitophagy assays; BNIP3 functional studies\",\n      \"journal\": \"Redox biology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — mechanistic claims are primarily from scRNA-seq and knockdown with limited biochemical validation described in the abstract\",\n      \"pmids\": [\"41865720\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Endothelial CEPT1 silencing suppresses MTTP (microsomal triglyceride transfer protein) expression and activity in co-cultured hepatocytes via a paracrine mechanism involving PPARα signaling, and this effect is rescued by fenofibrate treatment. Endothelial-specific Cept1 knockdown in mice decreased serum triglyceride and cholesterol levels and attenuated aortic atherosclerosis.\",\n      \"method\": \"In vitro co-culture of endothelial cells and hepatocytes with CEPT1 silencing; MTTP activity assay; endothelial-specific Cept1 KD mouse model; serum lipid analysis; aortic histology; fenofibrate rescue\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — preprint, single lab, paracrine mechanism inferred from co-culture and in vivo KD without full biochemical reconstitution\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"CEPT1 is a dual-specificity ER-resident enzyme that catalyzes the final steps of PC and PE biosynthesis via the Kennedy pathway by transferring phosphocholine or phosphoethanolamine from CDP-choline or CDP-ethanolamine to diacylglycerol; it preferentially uses unsaturated DAG substrates, its ER-synthesized products feedback-inhibit CCTα and regulate lipid droplet biogenesis, it functions upstream of PPARα in endothelial angiogenic signaling, and it also suppresses ferroptosis through interaction with LPCAT3 and phospholipases that degrade pro-ferroptotic PUFA-phospholipids.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CEPT1 is a dual-specificity, ER-resident enzyme that catalyzes the final committed step of the Kennedy pathway, transferring a phosphobase from CDP-choline or CDP-ethanolamine to diacylglycerol to generate phosphatidylcholine (PC) and phosphatidylethanolamine (PE) [#0]. It prefers unsaturated DAG acceptors and is subject to product activation, and it accounts for the majority of cellular choline-phospholipid biosynthesis [#0, #2]. Its ER localization is functionally distinct from the Golgi-resident related transferases EPT1 and CHPT1, which favor alkyl-acyl and plasmalogen/PUFA substrates, and only ER-synthesized PC made by CEPT1 feedback-regulates CCT\\u03b1 \\u2014 loss of CEPT1 drives posttranscriptional CCT\\u03b1 upregulation, dephosphorylation, and constitutive nuclear-membrane localization together with aberrant lipid droplet accumulation, all reversible by PC repletion [#1, #2, #3]. Beyond bulk phospholipid supply, CEPT1 is essential for endothelial proliferation, migration, and angiogenesis in vivo, acting upstream of a PPAR\\u03b1\\u2192VEGF-A\\u2192VEGFR2\\u2192Akt/eNOS signaling axis [#4, #6]. CEPT1 also interacts with and stabilizes LPCAT3 and thereby suppresses ferroptosis [#5]. No high-confidence structural model of the enzyme has been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established CEPT1 as a single dual-specificity enzyme producing both PC and PE, defining its core catalytic identity and substrate preferences.\",\n      \"evidence\": \"Mixed-micellar in vitro enzyme assay in a heterologous system lacking endogenous activity, with Km determination and inhibitor profiling\",\n      \"pmids\": [\"12216837\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structural basis for dual specificity or the inferred lipid activation sites\", \"In vitro kinetics do not establish in-cell flux contribution\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Resolved the division of labor among phosphobase transferases by showing CEPT1 is ER-localized and drives PE synthesis from shorter-chain species, distinct from Golgi-resident EPT1.\",\n      \"evidence\": \"Immunohistochemistry, CRISPR knockout cells, metabolic labeling, in vitro assay, and LC-MS lipidomics in HEK293\",\n      \"pmids\": [\"32576654\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not address regulation of CEPT1 substrate channeling\", \"Localization determinants not mapped\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Quantified CEPT1 as the dominant contributor to choline phospholipid biosynthesis relative to Golgi-resident CHPT1/CPT1.\",\n      \"evidence\": \"CRISPR KO/rescue HEK293 cells, radiolabeled choline labeling, qPCR, and deuterium-labeled LC-MS/MS\",\n      \"pmids\": [\"34331935\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specific relative contributions not established\", \"Does not address downstream signaling consequences\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Demonstrated that only ER-synthesized PC made by CEPT1 feedback-regulates CCT\\u03b1 activation state and lipid droplet biogenesis, linking the enzyme to lipid homeostatic control.\",\n      \"evidence\": \"CRISPR KO in U2OS, [14C]-choline labeling, CCT\\u03b1 localization imaging, PC liposome rescue, and LD quantification\",\n      \"pmids\": [\"36871755\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism of how ER-PC pool is sensed by CCT\\u03b1 not resolved\", \"Nuclear LD function not defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Placed CEPT1 upstream of PPAR\\u03b1 in endothelial angiogenic signaling through genetic epistasis, extending its role from lipid metabolism to vascular function.\",\n      \"evidence\": \"Conditional EC-specific Cept1 knockout, hindlimb ischemia model, Cept1/Ppara double KO, siRNA knockdown, and fenofibrate rescue\",\n      \"pmids\": [\"33214136\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How PC/PE metabolism mechanistically activates PPAR\\u03b1 not established\", \"Exogenous PC failed to rescue, leaving the lipid signal undefined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified a phospholipid-synthesis-independent role: CEPT1 binds and stabilizes LPCAT3 and suppresses ferroptosis.\",\n      \"evidence\": \"Proteomic interaction screen, co-immunoprecipitation, and ferroptosis assays with CEPT1 modulation\",\n      \"pmids\": [\"38430542\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Phospholipase interactions and PUFA-phospholipid degradation mechanism not biochemically resolved\", \"Direct vs indirect contribution to ferroptosis not separated from synthesis function\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Gain-of-function established CEPT1 as a positive driver of a PPAR\\u03b1\\u2192VEGF-A\\u2192VEGFR2\\u2192Akt/eNOS angiogenic cascade.\",\n      \"evidence\": \"EC-specific Cept1 overexpression mouse, scRNA-seq, inhibitor pathway dissection, and sprouting/ischemia assays\",\n      \"pmids\": [\"41263082\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab gain-of-function correlation; direct molecular link from CEPT1 to PPAR\\u03b1 still missing\", \"Inhibitor epistasis does not prove a linear pathway\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Connected CEPT1 deficiency to phospholipid imbalance that triggers ER stress and mitochondrial Ca2+/oxidative stress, and identified FOXA1 as a direct transcriptional activator in airway epithelium.\",\n      \"evidence\": \"FOXA1 transcriptional studies, CEPT1 KD/OE in airway epithelial cells, ER stress and Ca2+/ROS assays, asthma mouse model with rescue\",\n      \"pmids\": [\"42176270\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal chain from phospholipid imbalance to ER stress not dissected step-by-step\", \"Tissue specificity of FOXA1 regulation not generalized\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Linked CEPT1 to nucleotide-driven metabolic reprogramming, with CTPS1-supplied CTP boosting CEPT1 expression to support mitochondrial homeostasis and BNIP3 mitophagy in lymphoma cells.\",\n      \"evidence\": \"scRNA-seq, CTPS1 KD/OE in DLBCL cells, CEPT1 expression measurement, and mitophagy/BNIP3 assays\",\n      \"pmids\": [\"41865720\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Primarily scRNA-seq and knockdown with limited biochemical validation\", \"Direct effect of CEPT1 lipids on mitophagy not reconstituted\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CEPT1-derived phospholipid pools are mechanistically transduced into PPAR\\u03b1 activation and the structural basis of its dual catalytic specificity remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the enzyme\", \"Identity of the lipid signal coupling CEPT1 to PPAR\\u03b1 unknown\", \"Phospholipase partners in ferroptosis suppression unconfirmed\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [1, 2, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4, 6]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"LPCAT3\", \"CCTalpha\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}