title: Human fatty acid transport protein 2a/very long chain acyl-CoA synthetase 1 (FATP2a/Acsvl1) has a preference in mediating the channeling of exogenous n-3 fatty acids into phosphatidylinositol.
abstract: The trafficking of fatty acids across the membrane and into downstream metabolic pathways requires their activation to CoA thioesters. Members of the fatty acid transport protein/very long chain acyl-CoA synthetase (FATP/Acsvl) family are emerging as key players in the trafficking of exogenous fatty acids into the cell and in intracellular fatty acid homeostasis. We have expressed two naturally occurring splice variants of human FATP2 (Acsvl1) in yeast and 293T-REx cells and addressed their roles in fatty acid transport, activation, and intracellular trafficking. Although both forms (FATP2a (M(r) 70,000) and FATP2b (M(r) 65,000 and lacking exon3, which encodes part of the ATP binding site)) were functional in fatty acid import, only FATP2a had acyl-CoA synthetase activity, with an apparent preference toward very long chain fatty acids. To further address the roles of FATP2a or FATP2b in fatty acid uptake and activation, LC-MS/MS was used to separate and quantify different acyl-CoA species (C14-C24) and to monitor the trafficking of different classes of exogenous fatty acids into intracellular acyl-CoA pools in 293T-REx cells expressing either isoform. The use of stable isotopically labeled fatty acids demonstrated FATP2a is involved in the uptake and activation of exogenous fatty acids, with a preference toward n-3 fatty acids (C18:3 and C22:6). Using the same cells expressing FATP2a or FATP2b, electrospray ionization/MS was used to follow the trafficking of stable isotopically labeled n-3 fatty acids into phosphatidylcholine and phosphatidylinositol. The expression of FATP2a resulted in the trafficking of C18:3-CoA and C22:6-CoA into both phosphatidylcholine and phosphatidylinositol but with a distinct preference for phosphatidylinositol. Collectively these data demonstrate FATP2a functions in fatty acid transport and activation and provides specificity toward n-3 fatty acids in which the corresponding n-3 acyl-CoAs are preferentially trafficked into acyl-CoA pools destined for phosphatidylinositol incorporation.
authors.affiliation: Departments of Biochemistry, Lincoln, Nebraska 68588; Center for Cardiovascular Sciences, Albany Medical College, Albany, New York 12208.
authors.forename: Elaina M
authors.initials: EM
authors.lastname: Melton
authors.affiliation: Chemistry, University of Nebraska, Lincoln, Nebraska 68588.
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Cerny
authors.affiliation: Kennedy Krieger Research Institute, Baltimore, Maryland 21205.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Watkins
authors.affiliation: Departments of Biochemistry, Lincoln, Nebraska 68588.
authors.forename: Concetta C
authors.initials: CC
authors.lastname: DiRusso
authors.affiliation: Departments of Biochemistry, Lincoln, Nebraska 68588. Electronic address: pblack2@unl.edu.
authors.forename: Paul N
authors.initials: PN
authors.lastname: Black
mesh_terms: D020816:Amino Acid Motifs; D001692:Biological Transport; D015153:Blotting, Western; D002853:Chromatography, Liquid / Q000379:methods; D003066:Coenzyme A Ligases / Q000737:chemistry* / Q000378:metabolism; D050612:Fatty Acid Transport Proteins / Q000378:metabolism*; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism; D015525:Fatty Acids, Omega-3 / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D008954:Models, Biological; D010716:Phosphatidylinositols / Q000378:metabolism*; D020033:Protein Isoforms; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D000098859:Long-Chain-Fatty-Acid-CoA Ligase
chemical_list: D050612:Fatty Acid Transport Proteins; D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D010716:Phosphatidylinositols; D020033:Protein Isoforms; D003066:Coenzyme A Ligases; C101958:acetate-CoA ligase (ADP-forming); D000098859:Long-Chain-Fatty-Acid-CoA Ligase