Fatty acid transport and its regulation

我们已经克隆并鉴定了五种哺乳动物脂肪酸转运蛋白（FATPs）。FATP 1在心脏、脂肪细胞、肌肉和脑中以高水平表达。FATP 4主要表达在吸收性小密集上皮细胞的刷状缘中，并且对于LCFA的摄取是必需的。人FATP 6仅在心肌中表达，其水平在肥大组织中升高。我们的总体目标是了解脂肪酸转运及其调控的分子机制。我们专注于脂肪酸转运蛋白以及其他蛋白质：“清道夫”受体CD 36和SRI-BI;拉克（长链脂肪酰辅酶A合成酶）;和细胞溶质脂肪酸结合蛋白（脂肪酸结合蛋白），以及它们在心脏，脂肪细胞和肠上皮细胞中的脂肪酸转运中的作用。我们的具体目标是1）确定这些蛋白质是否功能协同以增强培养细胞对LCFA的转运，以及根据所涉及的转运机制，脂肪酸是否在进入时酯化为CoA。2)确定各种FATP、FABP、SR-BI/CD 36和拉克之间是否发生稳定的物理相互作用。3)通过反义实验确定哪种蛋白质是脂肪细胞LCFA摄取的限速蛋白质，无论是在不存在还是存在胰岛素的情况下。4)确定胰岛素如何刺激和TNF-α如何抑制脂肪细胞摄取LCFA 5）克隆和研究心脏特异性人FATP 6的推定嘌呤同源物。6)根据获得的结果，使用表达模型系统来测试FATP 1，FATP 4和其他蛋白质在LCFA摄取中的作用，并确定这些蛋白质在整个小鼠脂质代谢中的作用。因此，我们将1）确定这些候选脂肪酸转运蛋白在发育和成年小鼠心脏内的表达模式。2)使用FATP 1敲除和转基因FATP 1过表达小鼠，确定FATP 1在LCFA中的作用，脂肪组织和心脏以及横纹肌的摄取和脂质代谢。3)使用基因敲除小鼠，确定FAT 4、SR-BI和CD 36在吸收上皮细胞从小肠摄取LCFA中的作用。

We have cloned and characterized five mammalian fatty acid transport proteins (FATPs). FATP1 is expressed at high levels in heart, adipocytes, muscle, and brain. FATP4 is expressed predominantly in the brush border of the absorptive small intensive epithelial cells and is essential for uptake of LCFAs. Human FATP6 is expressed exclusively in heart muscle and its level is elevated in hypertrophic tissue. Our overall goal is to understand the molecular mechanism of fatty acid transport and its regulation. We focus on the FATPs as well as other proteins implicated in fatty acid transport: the "scavenger" receptors CD36 and SRI-BI; LACS (long chain fatty acyl CoA synthetase); and cytosolic FABPs (fatty acid binding proteins), and their roles in fatty acid transport in heart, adipocytes, and intestinal epithelial cells. Our specific aims are to 1) Determine whether these proteins functional synergize to enhance the transports of LCFAs by cultured cells and whether, depending on the transport mechanism involved, fatty acids are esterified to CoA upon entry. 2) Determine whether stable physical interactions occur between various FATPs, FABPs, SR-BI/CD36, and LACS. 3) Determine by antisense experiments which protein is rate-limiting for adipocyte LCFA uptake, both in the absence and presence of insulin. 4) Determine how insulin stimulates and TNF-alpha inhibits LCFA uptake by adipocytes 5) Clone and study the putative purine homologue of the cardiac-specific human FATP6. 6) Depending on the results obtained, use expression model systems to test the roles of FATP1, FATP4, and other proteins in LCFA uptake and determine the role of these proteins in whole-mouse lipid metabolism. Thus we will 1) Determine the expression pattern of these candidate fatty acid transport proteins within the developing and adult murine heart. 2) Using both FATP1 knockout and transgenic FATP1 over-expressing mice, determine the role of FATP1 in LCFA, uptake and lipid metabolism by adipose tissue and heart and striated muscle. 3) Using gene knock-out mice, determine the role of FAT4, SR- BI, and CD36 in uptake of LCFAs from the small intestine by the absorptive epithelial cells.