Investigation of the Molecular Mechanisms of Lipoprotein Lipase Inhibitors

 描述(由申请人提供)：血清甘油三酯升高与心血管疾病风险增加有关。脂蛋白脂酶(LPL)是一种分泌型酶，通过分解循环脂蛋白中的甘油三酯成分来清除血液中的脂质。LPL有许多大分子抑制剂。在人类群体中，这些大分子抑制剂的已知突变导致抑制LPL的能力降低。结果, LPL活性升高，血清甘油三酯降低。我们最近发现，其中一种蛋白质ANGPTL4是一种可逆的、非竞争性的LPL抑制剂，而不是以前认为的去折叠的分子伴侣。这种对ANGPTL4功能的新理解促使我们问，是否有其他LPL抑制剂以类似的机制作用于LPL。本提案侧重于从生物化学的角度定义LPL/抑制剂的相互作用。在目标1中，我们将定义这些抑制剂用于降低LPL活性的序列基序和动力学和分子机制。在目标2中，我们将确定LPL上被抑制剂识别的特征。在目标3中，我们问为什么LPL的一个变体可以增强体内的活性。为了实现这些目标，我们将结合蛋白质生物化学、结构蛋白质组学和单分子TIRF显微镜。这些目标的成功完成将提供对LPL活性和调节机制的精确的分子理解。由于LPL在人类甘油三酯代谢中的关键作用，这些发现为开发治疗高甘油三酯血症的新疗法带来了希望。

 DESCRIPTION (provided by applicant): Elevated serum triglycerides are associated with increased risk for cardiovascular disease. Lipoprotein lipase (LPL) is a secreted enzyme that clears lipids from the blood by hydrolyzing the triglycerides component of circulating lipoproteins. LPL has a number of macromolecular inhibitors. In human populations, known mutations in these macromolecular inhibitors result in reduced ability to inhibit LPL. As a result, LPL activity is increased and serum triglycerides are decreased. We recently discovered that one of these proteins, ANGPTL4, acts as a reversible, noncompetitive LPL inhibitor rather than an unfolding molecular chaperone as was previously believed. This new understanding of ANGPTL4 function led us to ask if other LPL inhibitors act on LPL using a similar mechanism. This proposal focuses on biochemically defining the LPL/inhibitor interaction. In Aim 1 we will define the sequence motifs and kinetic and molecular mechanisms used by these inhibitors to reduce LPL activity. In Aim 2, we will identify the features on LPL that are recognized by the inhibitors. In Aim 3 we ask why a variant of LPL has enhanced activity in vivo. To achieve these aims we will combine protein biochemistry, structural proteomics and single molecule TIRF microscopy. Successful completion of these aims will provide a precise molecular understanding of the mechanism of LPL activity and regulation. Because of LPL's key role in human triglyceride metabolism, these discoveries hold promise for developing new therapies for hypertriglyceridemia.