Mechanism of Fatty Acid Uptake by CD36

我的研究计划的总体目标是了解CD 36介导的脂肪酸（FA）跨细胞膜转运的机制和影响，从最基本的问题开始：CD 36的物理结构如何促进FA摄取？一直到体内的生理和病理生理变化。虽然今天被更广泛地接受，但蛋白质介导的FA摄取仍然存在争议，因为非离子化的FA可以快速翻转/翻转穿过膜。然而，触发器/触发器不会导致FA有效地掺入三酰甘油酯和磷脂的细胞池中。相反，当CD 36存在于膜上时，随后在FA的细胞衍生物中发现超过90%的FA。CD 36缺陷的小鼠和人类具有表型变化，这可以通过FA摄取缺陷来解释。最近发表的模型结构的CD 36提供了重要的新信息，允许合理的和战略的结构：功能询问的CD 36，也许是最终的答案FA摄取的争议。我们假设，基于结构模型，CD 36通道隔离FA通过膜，在那里他们翻转/翻转。CD 36定位于特定结构域、脂筏、抗洗涤剂结构域和小窝蛋白中，这些结构域可能充当运输枢纽。其他辅助CD 36的蛋白质可以物理相互作用，或者可以简单地富集。因此，我们设想CD 36通道FA细胞质脂肪酸结合蛋白（FABP）和脂肪酰辅酶A合成酶允许似乎单向FA流动和纳入细胞池。然而，我们假设CD 36的结构是结果的内在因素。本研究的目的是1。为了在FA通道中产生CD 36的突变体，使得它们是FA摄取死亡的，但在其他方面是有能力的，并且在细胞表面上正确表达，2.为了测试该（这些）突变体对巨噬细胞功能的影响，以及3.检验CD 36通过信号传导影响FA酯化的备择假设。这些目标补充并支持实验室中的其他工作，其中我们使用小鼠模型研究CD 36与细胞质FABP和脂肪酰辅酶A合成酶的共定位以及内皮细胞CD 36对全身FA摄取、肥胖、胰岛素抵抗和动脉粥样硬化的影响。这些项目还可以产生协同作用，因为为一个项目创造的试剂和技术可以被纳入其他项目，从一个项目获得的知识可以为其他项目提供信息。了解FA摄入细胞的基本原理增加了我们的科学知识，并有可能影响肥胖，胰岛素抵抗/糖尿病和心血管疾病的策略。

The overall objective of my research program is to understand the mechanism and impact of CD36 mediated transport of fatty acids (FA) across cell membranes, starting from the most basic question: how does the physical structure of CD36 facilitate FA uptake?, all the way to physiological and pathophysiological changes in vivo. Although more widely accepted today, protein mediated FA uptake remains controversial because un-ionized FA can rapidly flip/flop across membranes. Flip/flop, however, does not lead to productive incorporation of FA into cellular pools of triacylglycerides and phospholipids. In contrast, when CD36 is present on membranes, more than 90% of FA are subsequently found in cellular derivatives of FA. CD36-deficient mice and humans have phenotypic changes that could be explained by a defect in FA-uptake. The recently published model structure of CD36 provides important new information that allows rational and strategic structure:function interrogation of CD36 and perhaps a final answer to the FA uptake controversy. We hypothesize that, based on the structural model, a CD36 channel sequesters FA through to the membrane, where they flip/flop over. CD36 is localized in specific domains, lipid rafts, detergent resistant domains and caveolin, which may act as transport hubs. Other proteins which assist CD36 may interact physically, or may simply be enriched. Thus we imagine CD36 channels FA to cytoplasmic fatty acid binding proteins (FABP) and fatty acyl-CoA synthetase allowing for seemingly unidirectional FA flow and incorporation into cellular pools. It is the structure of CD36, however, that we hypothesize is intrinsic to the outcome. The objectives of this research proposal are 1. To create mutants of CD36 in the FA channel, such that they are FA-uptake dead, but otherwise competent, and expressed correctly on the cell surface, 2. To test the impact of this (these) mutant(s) on macrophage function and 3. To test an alternative hypothesis that CD36 affects FA esterification through signaling. These Aims complement and support other work in the lab in which we study CD36 co-localization with cytoplasmic FABPs and fatty acyl-CoA synthetase and the impact of endothelial cell CD36 on systemic FA uptake, obesity, insulin resistance and atherosclerosis using mouse models. The projects also synergize in that reagents and techniques created for one project can be incorporated into others, and knowledge gained from one informs the others. Understanding the fundamentals of FA uptake into cells increases our scientific knowledge and has the potential to effect strategies for obesity, insulin resistance/diabetes and cardiovascular diseases.