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

Department of Biochemistry, University of Nebraska, Lincoln, Nebraska 68588, USA.
Journal of Biological Chemistry (Impact Factor: 4.57). 07/2011; 286(35):30670-9. DOI: 10.1074/jbc.M111.226316
Source: PubMed


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.

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    • "Fads1 fatty acid desaturase 1, Fads2 fatty acid desaturase 2, Elovl2 elongase 2, Elovl5 elongase 5, Scd1 stearoyl-CoA desaturase 1, Elovl6 elongase 6, Fatp2 fatty acid transport protein 2, Fatp3 fatty acid transport protein 3, Fatp4 fatty acid transport protein 4, Fatp5 fatty acid transport protein 5, Acsl6 acyl-CoA synthetase long-chain 6, Fat/cd36 fatty acid translocase/cluster of differentiation 36, Fabp1 fatty acid binding protein 1, Fabp5 fatty acid binding protein 5, Fabp7 fatty acid binding protein 7. Data are mean ± SEM; n = 6–7; *p \ 0.05 Fig. 3 FATP2 protein levels in fasted versus fed mice. Data are mean ± SEM; n = 4; *p \ 0.05 transporters preferentially mediate uptake of n-3 and n-6 PUFA into cells and show high affinity for 22:6n-3 (Norris and Spector 2002; Marszalek et al. 2005; Xu et al. 1996; Mita et al. 2010; Nemecz et al. 1991; Melton et al. 2011, 2013). Expression of the Fatp5 transporter was also 1.5- fold higher in fasted animals compared with ad libitum fed animals. "
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    ABSTRACT: We investigated the effect of short-term fasting on coordinate changes in the fatty acid composition of adipose triacylglycerol (TAG), serum non-esterified fatty acids (NEFA), liver TAG, and serum TAG and phospholipids in mice fed ad libitum or fasted for 16 h overnight. In contrast to previous reports under conditions of maximal lipolysis, adipose tissue TAG was not preferentially depleted of n-3 PUFA or any specific fatty acids, nor were there any striking changes in the serum NEFA composition. Short-term fasting did, however, increase the hepatic proportion of n-3 PUFA, and almost all individual species of n-3 PUFA showed relative and absolute increases. The relative proportion of n-6 PUFA in liver TAG also increased but to a lesser extent, resulting in a significant decrease in the n-6:n-3 PUFA ratio (from 14.3 ± 2.54 to 9.6 ± 1.20), while the proportion of MUFA decreased significantly and SFA proportion did not change. Examination of genes involved in PUFA synthesis suggested that hepatic changes in the elongation and desaturation of precursor lipids could not explain this effect. Rather, an increase in the expression of fatty acid transporters specific for 22:6n-3 and other long-chain n-3 and n-6 PUFA likely mediated the observed hepatic enrichment. Analysis of serum phospholipids indicated a specific increase in the concentration of 22:6n-3 and 16:0, suggesting increased specific synthesis of DHA-enriched phospholipid by the liver for recirculation. Given the importance of blood phospholipid in distributing DHA to neural tissue, these findings have implications for understanding the adipose-liver-brain axis in n-3 PUFA metabolism.
    Genes & Nutrition 11/2015; 10(6). DOI:10.1007/s12263-015-0490-2 · 2.79 Impact Factor
    • "A naturally occurring variant of FATP2, FATP2b, has no ACSVL activity, but nevertheless enhances exogenous FA import when expressed in fat1∆ faa1∆ yeast. This is consistent with distinct transport and activation functions of FATP2 [37]. FATP5, also known as Bile acyl-coA synthetase, is the only murine protein with no ACSVL activity in yeast cells. "
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    ABSTRACT: The dysregulation of lipid metabolism has been implicated in various diseases, including diabetes, cardiopathies, dermopathies, retinal and neurodegenerative diseases. Mouse models have provided insights into lipid metabolism. However, progress in the understanding of these pathologies is hampered by the multiplicity of essential cellular processes and genes that modulate lipid metabolism. Drosophila and C. elegans have emerged as simple genetic models to improve our understanding of these metabolic diseases. Recent studies have characterized fatty acid transport protein (fatp) mutants in Drosophila and C. elegans, establishing new models of cardiomyopathy, retinal degeneration, fat storage disease and dermopathies. These models have generated novel insights into the physiological role of the Fatp protein family in vivo in multicellular organisms, and are likely to contribute substantially to progress in understanding the etiology of various metabolic disorders. Here, we describe and discuss the mechanisms underlying invertebrate fatp mutant models in the light of the current knowledge relating to FATPs and lipid disorders in vertebrates.
    Progress in lipid research 09/2015; 60. DOI:10.1016/j.plipres.2015.08.001 · 10.02 Impact Factor
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    • "2.1. Cell growth, expression of FATP2, and incubation of different classes of fatty acids Stable T-REx HEK293 cells allowing the regulated expression of FATP2 or transformed with the vector (control) have been previously described [12]. Cells were routinely maintained in DMEM medium containing 10% FBS; expression of FATP2 was accomplished by the addition of tetracycline to a final concentration of 2 lg/ml for 48 h; the cells are harvested and then subjected to analytical studies as detailed below. "
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    ABSTRACT: In mammals, the fatty acid transport proteins (FATP1 through FATP6) are members of a highly conserved family of proteins, which function in fatty acid transport proceeding through vectorial acylation and in the activation of very long chain fatty acids, branched chain fatty acids and secondary bile acids. FATP1, 2 and 4, for example directly function in fatty acid transport and very long chain fatty acids activation while FATP5 does not function in fatty acid transport but activates secondary bile acids. In the present work, we have used stable isotopically labeled fatty acids differing in carbon length and saturation in cells expressing FATP2 to gain further insights into how this protein functions in fatty acid transport and intracellular fatty acid trafficking. Our previous studies showed the expression of FATP2 modestly increased C16:0-CoA and C20:4-CoA and significantly increased C18:3-CoA and C22:6-CoA after 4hr. The increases in C16:0-CoA and C18:3-CoA suggest FATP2 must necessarily partner with a long chain acyl CoA synthetase (Acsl) to generate C16:0-CoA and C18:3-CoA through vectorial acylation. The very long chain acyl CoA synthetase activity of FATP2 is consistent in the generation of C20:4-CoA and C22:6-CoA coincident with transport from their respective exogenous fatty acids. The trafficking of exogenous fatty acids into phosphatidic acid (PA) and into the major classes of phospholipids (phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidyserine (PS)) resulted in distinctive profiles, which changed with the expression of FATP2. The trafficking of exogenous C16:0 and C22:6 into PA was significant where there was 6.9- and 5.3-fold increased incorporation, respectively, over the control; C18:3 and C20:4 also trended to increase in the PA pool while there were no changes for C18:1 and C18:2. The trafficking of C18:3 into PC and PI trended higher and approached significance. In the case of C20:4, expression of FATP2 resulted in increases in all four classes of phospholipid, indicating little selectivity. In the case of C22:6, there were significant increases of this exogenous fatty acids being trafficking into PC and PI. Collectively, these data support the conclusion that FATP2 has a dual function in the pathways linking the transport and activation of exogenous fatty acids. We discuss the differential roles of FATP2 and its role in both fatty acid transport and fatty acid activation in the context of lipid homeostasis.
    Biochemical and Biophysical Research Communications 10/2013; 440(4). DOI:10.1016/j.bbrc.2013.09.137 · 2.30 Impact Factor
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