Sterol carrier protein-2/sterol carrier protein-x expression differentially alters fatty acid metabolism in L cell fibroblasts.
Sterol carrier protein-2 (SCP-2) and SCP-x are ubiquitous proteins found in all mammalian tissues. Although both proteins interact with fatty acids, their relative contributions to the uptake, oxidation, and esterification of straight-chain (palmitic) and branched-chain (phytanic) fatty acids in living cells has not been resolved. Therefore, the effects of each gene product on fatty acid metabolism was individually examined. Based on the following, SCP-2 and SCP-x did not enhance the uptake/translocation of fatty acids across the plasma membrane into the cell: i) a 2-fold increase in phytanic and palmitic acid uptake was observed at long incubation times in SCP-2- and SCP-x-expressing cells, but no differences were observed at initial time points; ii) uptake of 2-bromo-palmitate, a nonoxidizable, poorly metabolizable fatty acid analog, was unaffected by SCP-2 or SCP-x overexpression; and iii) SCP-2 and SCP-x expression did not increase targeting of radiolabeled phytanic and palmitic acid to the unesterified fatty acid pool. Moreover, SCP-2 and SCP-x expression enhanced fatty acid uptake by stimulating the intracellular metabolism via fatty acid oxidation and esterification. In summary, these data showed for the first time that SCP-2 and SCP-x stimulate oxidation and esterification of branched-chain as well as straight-chain fatty acids in intact cells.
Atshaves
Barbara P
BP
Department of Physiology and Pharmacology, Texas A&M University, TVMC College Station, TX 77843-4466, USA.
Storey
Stephen M
SM
Schroeder
Friedhelm
F
D000101:Acetyl-CoA C-Acetyltransferase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism*; D015870:Gene Expression; D007739:L Cells; D051379:Mice; D010084:Oxidation-Reduction; D019308:Palmitic Acid / Q000378:metabolism; D010831:Phytanic Acid / Q000378:metabolism; D013997:Time Factors; D014316:Tritium
D002352:Carrier Proteins; D005227:Fatty Acids; C072087:sterol carrier proteins; D014316:Tritium; D010831:Phytanic Acid; D019308:Palmitic Acid; D000101:Acetyl-CoA C-Acetyltransferase