title: FATP1 channels exogenous FA into 1,2,3-triacyl-sn-glycerol and down-regulates sphingomyelin and cholesterol metabolism in growing 293 cells.
abstract: Biosynthesis of lipids was investigated in growing 293 cells stably expressing fatty acid (FA) transport protein 1 (FATP1), a bifunctional polypeptide with FA transport as well as fatty acyl-CoA synthetase activity. In short-term (30 s) incubations, FA uptake was increased in FATP1 expressing cells (C8 cells) compared with the vector (as determined by BODIPY 3823 staining and radioactive FA uptake). In long-term (4 h) incubations, incorporation of [(14)C]acetate, [3H]oleic acid, or [(14)C]lignoceric acid into 1,2,3-triacyl-sn-glycerol (TG) was elevated in C8 cells compared with vector, whereas incorporation of radiolabel into glycerophospholipids was unaltered. The increase in TG biosynthesis correlated with an increase in 1,2-diacyl-sn-glycerol acyltransferase activity in C8 cells compared with vector. In contrast, incorporation of [(14)C]acetate into sphingomyelin (SM) and cholesterol, and [3H]oleic acid or [(14)C]lignoceric acid into SM was reduced due to a reduction in de novo biosynthesis of these lipids in C8 cells compared with vector. The results indicate that exogenously supplied FAs, and their subsequently produced acyl-CoAs, are preferentially channeled by an FATP1 linked mechanism into the TG biosynthetic pathway and that such internalized lipids down-regulate de novo SM and cholesterol metabolism in actively growing 293 cells.
authors.affiliation: Department of Pharmacology, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Grant M
authors.initials: GM
authors.lastname: Hatch
authors.forename: Anne J
authors.initials: AJ
authors.lastname: Smith
authors.forename: Fred Y
authors.initials: FY
authors.lastname: Xu
authors.forename: Angela M
authors.initials: AM
authors.lastname: Hall
authors.forename: David A
authors.initials: DA
authors.lastname: Bernlohr
mesh_terms: D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D051242:Caveolin 1; D022461:Caveolins; D002455:Cell Division; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D003066:Coenzyme A Ligases / Q000378:metabolism; D050612:Fatty Acid Transport Proteins; D005227:Fatty Acids / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D019301:Oleic Acid / Q000378:metabolism; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D013109:Sphingomyelins / Q000378:metabolism*; D014226:Triazenes / Q000494:pharmacology; D014280:Triglycerides / Q000378:metabolism*; D000098859:Long-Chain-Fatty-Acid-CoA Ligase
chemical_list: D002352:Carrier Proteins; D051242:Caveolin 1; D022461:Caveolins; D050612:Fatty Acid Transport Proteins; D005227:Fatty Acids; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D012097:Repressor Proteins; C493568:SLC27A1 protein, human; D029701:Saccharomyces cerevisiae Proteins; D013109:Sphingomyelins; D014226:Triazenes; D014280:Triglycerides; D019301:Oleic Acid; C034613:triacsin C; D002784:Cholesterol; D003066:Coenzyme A Ligases; C090799:FAA2 protein, S cerevisiae; D000098859:Long-Chain-Fatty-Acid-CoA Ligase