Oleic acid distribution in small intestinal epithelial cells expressing intestinal-fatty acid binding protein.
Intestinal-fatty acid binding protein (I-FABP) has been proposed to target long chain fatty acids (LCFA) to triglyceride synthesis pathways in the intestinal epithelium. In the present studies hBRIE 380i cells, which endogenously express I-FABP only when fully differentiated, were used to investigate the role of I-FABP in LCFA incorporation and targeting by examining the relative distribution of [3H]-oleic acid in cellular lipids in these cells. [3H]-oleic acid incorporation into triglyceride was significantly higher in hBRIE 380i cells expressing I-FABP than in cells not expressing I-FABP. After 15 min, 1 and 4 h of incubation, cells expressing I-FABP incorporated 24.0%, 34.0% and 43.9% of [3H]-oleic acid into triglyceride, while newly confluent cells (no I-FABP expression) incorporated 15.6%, 18.3% and 31.9%. An I-FABP negative cell line, hBRIE 380i-neg cells, was stably transfected to investigate the effect of adding I-FABP to small intestinal epithelial cell lines. No measurable differences in [3H]-oleic acid incorporation into triglyceride was detected in these transfectants. Additionally I-FABP expression had no effect on [3H]-oleic acid incorporation or distribution within phospholipid subclasses in hBRIE 380i or transfected hBRIE 380i-neg fabpi cells. Our data from hBRIE 380i cells suggest that I-FABP can target LCFA to triglyceride synthesis pathway. However, endogenous I-FABP expression was also correlated to cellular differentiation and therefore raises the possibility that other differentiation-dependent factors may have a role in LCFA targeting. Because no effects of I-FABP were detected in the transfected hBRIE 380i-neg fabpi cells, it is concluded that factors in addition to I-FABP play a major role in determining the metabolic fate of LCFA in small intestinal epithelial cells. (c) 1998 Elsevier Science B.V.
Holehouse
E L
EL
Department of Nutritional Sciences, University of California, 119 Morgan Hall, Berkeley, CA 94720, USA.
Liu
M L
ML
Aponte
G W
GW
D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D004847:Epithelial Cells / Q000378:metabolism; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D018996:Myelin P2 Protein / Q000378:metabolism*; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D019301:Oleic Acid / Q000493:pharmacokinetics*; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D014162:Transfection
D002352:Carrier Proteins; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D018996:Myelin P2 Protein; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D010743:Phospholipids; D019301:Oleic Acid