Murphy E J, Prows D R, Jefferson J R, Schroeder F
Department of Physiology and Pharmacology, Texas A and M University, College Station 77843-4466, USA.
Biochim Biophys Acta. 1996 Jun 11;1301(3):191-8. doi: 10.1016/0005-2760(96)00024-0.
The role of cytosolic liver fatty acid binding protein (L-FABP) in fatty acid uptake and metabolism was examined using cultured L-cell fibroblasts transfected with the cDNA encoding for L-FABP. [3H]Oleic acid was used to determine the effects of intracellular esterification on fatty acid uptake and to determine esterified fatty acid localization to specific lipid classes. cis-Parinaric acid, a poorly esterified fatty acid, was used to determine uptake in the absence of any appreciable esterification. High-expression L-cells had a 80% and 50% greater initial uptake rate for both [3H]oleic acid and cis-parinaric acid, respectively compared to low-expression L-cells. Maximal uptake of [3H]oleic acid did not plateau because of intracellular esterification. In high-expressing cells, maximal cis-parinaric acid uptake rapidly plateaued at a level 34% higher than in low-expression cells. After 1 min of incubation, the majority of cellular [3H]oleic acid was unesterified, with the bulk of the esterified portion preferentially localized to phospholipids. After 5 and 30 min, cells expressing L-FABP esterified a significantly greater amount of [3H]oleic acid into both the neutral lipid and phospholipid fractions than did low-expression cells. L-FABP expression also selectively stimulated [3H]oleic acid incorporation into choline glycerophospholipids. Thus, L-FABP expression not only stimulated fatty acid uptake at all time points, but also stimulated intracellular esterification into specific lipid pools. These results show in detail for the first time using an intact cell culture system that L-FABP expression not only stimulated fatty acid uptake, but also increased intracellular esterification of exogenously supplied fatty acids.
利用转染了编码胞质肝脂肪酸结合蛋白（L-FABP）的cDNA的培养L细胞成纤维细胞，研究了胞质肝脂肪酸结合蛋白（L-FABP）在脂肪酸摄取和代谢中的作用。[3H]油酸用于确定细胞内酯化对脂肪酸摄取的影响，并确定酯化脂肪酸在特定脂质类别的定位。顺式十八碳四烯酸是一种酯化程度较低的脂肪酸，用于确定在没有任何明显酯化的情况下的摄取情况。与低表达L细胞相比，高表达L细胞对[3H]油酸和顺式十八碳四烯酸的初始摄取率分别高出80%和50%。由于细胞内酯化，[3H]油酸的最大摄取量没有达到平台期。在高表达细胞中，顺式十八碳四烯酸的最大摄取量迅速达到平台期，比低表达细胞高34%。孵育1分钟后，大多数细胞内的[3H]油酸未被酯化，酯化部分的大部分优先定位于磷脂。孵育5分钟和30分钟后，表达L-FABP的细胞将显著更多的[3H]油酸酯化到中性脂质和磷脂部分，而低表达细胞则不然。L-FABP的表达还选择性地刺激了[3H]油酸掺入胆碱甘油磷脂中。因此，L-FABP的表达不仅在所有时间点刺激了脂肪酸摄取，还刺激了细胞内向外源供应脂肪酸的特定脂质池的酯化。这些结果首次使用完整的细胞培养系统详细表明，L-FABP的表达不仅刺激了脂肪酸摄取，还增加了外源供应脂肪酸的细胞内酯化。
