Liver and intestinal fatty acid-binding protein expression increases phospholipid content and alters phospholipid fatty acid composition in L-cell fibroblasts.
Although fatty acid-binding proteins (FABP) differentially affect fatty acid uptake, nothing is known regarding their role(s) in determining cellular phospholipid levels and phospholipid fatty acid composition. The effects of liver (L)- and intestinal (I)-FABP expression on these parameters were determined using stably transfected L-cells. Expression of L- and I-FABP increased cellular total phospholipid mass (nmol/mg protein) 1.7- and 1.3-fold relative to controls, respectively. L-FABP expression increased the masses of choline glycerophospholipids (ChoGpl) 1.5-fold, phosphatidylserine (PtdSer) 5.6-fold, ethanolamine glycerophospholipids 1.4-fold, sphingomyelin 1.7-fold, and phosphatidylinositol 2.6-fold. In contrast, I-FABP expression only increased the masses of ChoGpl and PtdSer, 1.2- and 3.1-fold, respectively. Surprisingly, both L- and I-FABP expression increased ethanolamine plasmalogen mass 1.6- and 1.1-fold, respectively, while choline plasmalogen mass was increased 2.3- and 1.7-fold, respectively. The increase in phospholipid levels resulted in dramatic 48 and 33% decreases in the cholesterol-to-phospholipid ratio in L- and I-FABP expressing cells, respectively. L-FABP expression generally increased polyunsaturated fatty acids, primarily by increasing 20:4n-6 and 22:6n-3, while decreasing 18:1n-9 and 16:1n-7. I-FABP expression generally increased only 20:4n-6 proportions. Hence, expression of both I- and L-FABP differentially affected phospholipid mass, class composition, and acyl chain composition. Although both proteins enhanced phospholipid synthesis, the effect of L-FABP was much greater, consistent with previous work suggesting that these two FABP differentially affect lipid metabolism.
Murphy
E J
EJ
Department of Physiology and Pharmacology, Texas A & M University, TVMC, College Station 77843-4466, USA. murphye@mail.nih.gov
Prows
D R
DR
Stiles
T
T
Schroeder
F
F
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007739:L Cells; D008099:Liver / Q000378:metabolism; D051379:Mice; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D010743:Phospholipids / Q000737:chemistry* / Q000378:metabolism*; D010955:Plasmalogens / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection
D002352:Carrier Proteins; C493320:Fabp1 protein, mouse; C082667:Fabp5 protein, mouse; C086936:Fabp7 protein, mouse; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D010743:Phospholipids; D010955:Plasmalogens; D011994:Recombinant Proteins; D002784:Cholesterol