Regulation of Peripheral Protein-Membrane Interactions by Lipid Second Messengers

描述（由申请人提供）：在细胞和细胞外水平，心血管疾病和其他疾病的特征是脂基结构（如脂蛋白和细胞膜）富含磷脂的表面的动态重塑。这种重塑涉及脂质代谢物表面的生成，称为脂质第二信使，以二酰基甘油为例。对一种产生这些代谢物的脂肪酶的研究表明，它们的存在是脂肪酶从周围的水介质转移到它起作用的表面的关键条件。此外，脂肪酶易位需要这些脂质第二信使的水平超过临界值。低于此值，二酰基甘油与表面磷脂络合，转运受到抑制。我们假设这种调节机制不仅对脂肪酶的功能至关重要，而且对许多其他结构无关的蛋白质的功能至关重要，这些蛋白质对细胞稳态和疾病过程至关重要。该项目的目标是通过确定二酰基甘油调节表面寻找的程度和机制来测试这一假设，所选蛋白质的独立折叠单元，即结构域，到高度控制的模型脂质表面。目的1研究确定了二酰基甘油和其他脂类在表面的预先分布如何调节结构域向表面转运的能力。目的2研究确定结构域和表面内二酰基甘油的横向相互作用如何调节其在表面上花费的时间。目的3研究确定存在于表面的多结构域蛋白的一个结构域如何与二酰基甘油相互作用，产生“自组装受体”，以影响该蛋白的另一个表面寻找结构域的易位。这些蛋白结构域是载脂蛋白E、munc 13-1和胰脂肪酶的一部分，并作为一系列其他生物学上重要的蛋白共享其结构域基序的模型。使这些研究得以进行的是为这个项目开发的新方法和独特的新仪器。该项目的完成将更好地了解二酰基甘油调节基本生物过程的机制，如胆固醇清除（载脂蛋白E）和神经传递（munc 13-1）。此外，研究结果预计将提出调节其他过程的策略，这些过程严重依赖于脂质表面组织。

DESCRIPTION (provided by applicant): At both cellular and extracellular levels, cardiovascular and other diseases are characterized by the dynamic remodeling of the phospholipid-rich surfaces of lipid-based structures, like lipoproteins and cell membranes. This remodeling involves the generation in the surface of lipid metabolites, termed lipid second messengers, exemplified by diacylglycerols. Studies of one lipase that generates these metabolites have shown that their presence is a key requirement for the lipase to translocate from the surrounding aqueous medium to the surface where it functions. Moreover, lipase translocation requires a level of these lipid second messengers that exceeds a critical value. Below this value diacylglycerols are complexed with surface phospholipids and translocation is inhibited. We hypothesize that this regulatory mechanism is essential to the functions of not only lipases but many other, structurally-unrelated proteins that are crucial to cellular homeostasis and disease processes. The goal of this project is to test that hypothesis by determining the extent to which and mechanism by which diacylglycerol regulates the translocation of surface-seeking, independent folding units of selected proteins, i.e. domains, to and from highly controlled model lipid surfaces. Aim 1 studies determine how preexisting distribution of diacylglycerol and other lipid species in the surface regulates the ability of a domain to translocate to the surface. Aim 2 studies determine how lateral interaction of the domain and diacylglycerol within the surface regulates the time it spends at the surface. Aim 3 studies determine how the presence of one domain of a multi-domain protein residing in a surface can interact with diacylglycerol to produce a "self-assembled receptor" for effecting the translocation of another surface-seeking domain of that protein. The protein domains are parts of apolipoprotein E, munc 13-1 and pancreatic lipase and serve as models for a range of other biologically important proteins that share their domain motifs. Enabling these studies to be carried out is new methodology and unique new instrumentation developed for this project. The completion of this project will provide better understanding of the mechanisms by which diacylglycerols regulate essential biological processes, like cholesterol clearance (apolipoprotein E) and nerve transmission (munc 13-1). Moreover, results are expected to suggest strategies for regulating other processes which depend critically on the lipid surface organization.