Metallothionein-IIA promoter induction alters rat intestinal fatty acid binding protein expression, fatty acid uptake, and lipid metabolism in transfected L-cells.
Mouse L-cell fibroblasts, transfected with the cDNA encoding for rat intestinal fatty acid-binding protein (I-FABP) under the control of the human metallothionein-IIA promoter, were tested for their protein inducibility by the heavy metals cadmium (Cd2+) and zinc (Zn2+). I-FABP levels were quantitated by Western immunoblotting. Expression of I-FABP in all transfected cell lines tested was induced several-fold by optimized levels of Cd2+ and Zn2+. Induction conditions had no effect on cell growth rates or cell densities for any of the cell lines. Induction of high I-FABP-expressing cells (H141) decreased the initial rate and extent of uptake of cis-parinaric acid, a nonmetabolizable fatty acid, and of [3H]oleic acid, an esterifiable fatty acid. These effects of induction were specific for I-FABP-expressing cells since they were not observed in control cells or cells expressing a high level of liver (L-) FABP. Induction of H141 cells also significantly altered the esterification and distribution of exogenous [3H]oleic acid, especially among triglycerides and phosphatidylcholine, but less so among other glycero-phospholipids, cholesteryl esters, and phosphatidylethanolamine. Induction of H141 cells normalized [3H]oleic acid esterification into cholesteryl esters, phosphatidylcholine, total neutral lipids, and total phospholipids such that they no longer differed from control levels. In contrast, induction did not normalize [3H]oleic acid esterification into triacylglycerols and phosphatidylethanolamine to control levels in H141 cells; both remained significantly increased over control cells. Therefore, promoter induction levels of Cd2+ and Zn2+ enhanced I-FABP expression in H141 cells, thereby modulating both fatty acid uptake and intracellular esterification into neutral and phospholipids.
Prows
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Division of Pharmacology and Medicinal Chemistry, College of Pharmacy, University of Cincinnati, Ohio 45267-0004, USA.
Schroeder
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D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics*; D002413:Cations, Divalent; D002455:Cell Division; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000378:metabolism*; D007739:L Cells; D050356:Lipid Metabolism; D008668:Metallothionein / Q000235:genetics*; D008670:Metals; D051379:Mice; D018996:Myelin P2 Protein / Q000235:genetics*; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D011401:Promoter Regions, Genetic; D051381:Rats; D014162:Transfection
D002352:Carrier Proteins; D002413:Cations, Divalent; C493319:FABP1 protein, human; C493320:Fabp1 protein, mouse; C493321:Fabp1 protein, rat; C082667:Fabp5 protein, mouse; C086936:Fabp7 protein, mouse; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D008670:Metals; D018996:Myelin P2 Protein; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D008668:Metallothionein