Mechanism of Fatty Acid Uptake by CD36

CD36 摄取脂肪酸的机制

• 批准号: RGPIN-2016-05157
• 负责人: Febbraio, Maria
• 金额: $ 2.26万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=650549
• 关键词: Mechanism; Fatty; Acid; Uptake; CD36

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.

我的研究计划的总体目标是了解CD36介导的脂肪酸（FA）跨细胞膜运输的机制和影响，从最基本的问题开始：CD36的物理结构如何促进FA的摄取？，一直到体内的生理和病理生理变化。尽管目前已被广泛接受，但蛋白质介导的FA摄取仍然存在争议，因为未电离的FA可以快速地跨膜翻转/翻转。然而，翻转/翻转并不会导致FA进入三酰甘油和磷脂的细胞池中。相反，当CD36存在于膜上时，超过90%的FA随后在FA的细胞衍生物中被发现。cd36缺陷小鼠和人类的表型变化可以用fa摄取缺陷来解释。最近发表的CD36模型结构提供了重要的新信息，允许合理和战略性的结构：CD36的功能询问，也许是FA摄取争议的最终答案。我们假设，基于结构模型，CD36通道将FA隔离到膜上，在那里它们翻转/翻转。CD36定位于特定的结构域，脂筏，耐洗涤剂结构域和小窝蛋白，这些结构域可能作为运输枢纽。其他辅助CD36的蛋白质可能会发生物理相互作用，或者只是被富集。因此，我们设想CD36通道FA到细胞质脂肪酸结合蛋白（FABP）和脂肪酰基辅酶a合成酶，允许FA表面上单向流动并合并到细胞池中。然而，我们假设CD36的结构与结果是内在的。本研究计划的目标是：1。2.在FA通道中产生CD36突变体，使它们在FA摄取上死亡，但在其他方面有能力，并在细胞表面正确表达。为了测试这个（这些）突变体对巨噬细胞功能的影响。为了验证CD36通过信号传导影响FA酯化的另一种假设。这些目标补充和支持了我们在实验室中研究CD36与细胞质FABPs和脂肪酰基辅酶a合成酶共定位以及内皮细胞CD36对全身FA摄取、肥胖、胰岛素抵抗和动脉粥样硬化的影响的其他工作。这些项目还具有协同作用，因为为一个项目创建的试剂和技术可以合并到其他项目中，并且从一个项目中获得的知识可以通知其他项目。了解FA进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。