Liver fatty acid-binding protein gene ablation inhibits branched-chain fatty acid metabolism in cultured primary hepatocytes
Liver fatty acid-binding protein gene ablation inhibits branched-chain fatty acid metabolism in cultured primary hepatocytes
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DOI：
10.1074/jbc.m313571200
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发表时间：
2004-07-23
影响因子：
4.8
通讯作者：
Schroeder, F
中科院分区：
文献类型：
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作者：
Atshaves, BP;McIntosh, AM;Schroeder, F
尽管肝脏脂肪酸结合蛋白(L-FABP)在正常直链脂肪酸的摄取、转运、线粒体氧化和酯化中的作用已被广泛研究，但对于L-FABP在过氧体氧化和支链脂肪酸代谢中的作用几乎一无所知。因此，我们选择了植酸(饮食中最常见的支链脂肪酸)来解决从L-FABP基因去除(-/-)和野生型(+/+)小鼠的肝脏分离的原代肝细胞中的这些问题。这些研究提供了三个新的见解：第一，L-FABP基因去除最大程度地减少了植酸摄取，但不是最初的3.2倍。由于质膜脂肪酸转运体/转位酶蛋白(谷草转氨酶、脂肪酸转运蛋白和脂肪酸转位酶)分别上调5.3、1.6和1.4倍，植酸摄取的初始水平没有明显变化。第二，L-FABP基因缺失抑制了植酸过氧化体的氧化和微粒体酯化。这些效应与多光子荧光光漂白恢复所证明的细胞质脂肪酸转运减少是一致的，其中L-FABP基因去除使NbD-硬脂酸运动的细胞质扩散成分减少了2倍，而不是细胞膜。第三，L-FABP基因去除的肝细胞的脂质分析显示脂肪酸表型发生了变化。游离脂肪酸和甘油三酯水平分别下降了1.9倍和1.6倍。综上所述，从L-FABP(+/+)和L-FABP(-/-)小鼠分离的原代肝细胞的实验结果首次证实了L-FABP在支链脂肪酸的摄取和代谢中的生理作用。
Whereas the role of liver fatty acid-binding protein (L-FABP) in the uptake, transport, mitochondrial oxidation, and esterification of normal straight-chain fatty acids has been studied extensively, almost nothing is known regarding the function of L-FABP in peroxisomal oxidation and metabolism of branched-chain fatty acids. Therefore, phytanic acid ( most common dietary branched-chain fatty acid) was chosen to address these issues in cultured primary hepatocytes isolated from livers of L-FABP gene- ablated (-/-) and wild type (+/+) mice. These studies provided three new insights: First, L-FABP gene ablation reduced maximal, but not initial, uptake of phytanic acid 3.2-fold. Initial uptake of phytanic acid uptake was unaltered apparently due to concomitant 5.3-, 1.6-, and 1.4-fold up-regulation of plasma membrane fatty acid transporter/translocase proteins ( glutamic-oxaloacetic transaminase, fatty acid transport protein, and fatty acid translocase, respectively). Second, L-FABP gene ablation inhibited phytanic acid peroxisomal oxidation and microsomal esterification. These effects were consistent with reduced cytoplasmic fatty acid transport as evidenced by multiphoton fluorescence photobleaching recovery, where L-FABP gene ablation reduced the cytoplasmic, but not membrane, diffusional component of NBD-stearic acid movement 2-fold. Third, lipid analysis of the L-FABP gene- ablated hepatocytes revealed an altered fatty acid phenotype. Free fatty acid and triglyceride levels were decreased 1.9- and 1.6-fold, respectively. In summary, results with cultured primary hepatocytes isolated from L-FABP (+/+) and L- FABP (-/-) mice demonstrated for the first time a physiological role of L- FABP in the uptake and metabolism of branched-chain fatty acids.