Molecular Basis of Oxidative Modification of LDL

LDL 氧化修饰的分子基础

• 批准号: 7094647
• 负责人: LAWRENCE M SAYRE
• 金额: $ 44.26万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-05-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7094647
• 关键词: adduct; apolipoprotein B; atherosclerosis; blood lipoprotein metabolism; blood lipoprotein transport; cholesterol; immunocytochemistry; laboratory mouse; laboratory rabbit; liquid chromatography mass spectrometry; low density lipoprotein; low density lipoprotein receptor; macrophage; mass spectrometry; membrane transport proteins; oxidized lipid; peroxidation; phosphatidylcholines; posttranslational modifications; protein localization; protein structure function; two dimensional gel electrophoresis

DESCRIPTION (provided by applicant): Substantial evidence suggests that the accumulation and subsequent poor processing of oxidatively modified low density lipoprotein (oxLDL) by macrophages in the arterial wall contributes to the initial stages of atherogenesis. Oxidative modification of LDL involves the derivatization of its constituent apolipoprotein B by reactive aldehydic breakdown products of lipid peroxidation, including HNE. The chemistry of protein adduction by these aldehydes is highly complex and includes cross-linking. A major breakthrough of the current funding period was the finding that uptake of oxLDL by macrophages may be largely mediated by the recognition of oxidized phospholipids in oxLDL by CD36. We further discovered that the HNE-like products (and their derivatives) resulting from "mirror-image" oxidation of the arachidonyl and linoleyl chains of phospholipids serve as CD36 ligands. Further studies are proposed to bring thorough definition to the structural basis of oxLDL recognition by and accumulation within macrophage cells. Recent pilot studies suggest that oxidized constituents in oxLDL may interfere not only with lipoprotein processing within, but also cholesterol efflux from macrophage cells exposed to oxLDL. A major new aim of the next funding period is to clarify the nature of the inhibitory effects of oxLDL on cholesterol efflux. Our working hypothesis is that oxidative changes to LDL contribute to its uptake into and deficient processing within macrophage cells, and that oxLDL itself or constituents emanating from it inhibit one or more mechanisms of cholesterol efflux, all of which together act as an important determinant of foam cell formation. We will continue to define lipoxidation-dependent protein adduction chemistry, including mass spectrometric approaches to identifying macrophage proteins that are particularly susceptible to modification as a result of exposure of these cells to oxLDL. This latter aim will be aided by continued development of immunochemical probes for specific adducts, also useful for identifying the nature of late-stage adducts present in human atheroma. The new work proposed continues to take advantage of the pooled expertise of three individual investigators at neighboring research institutions, particularly with respect to the application of novel structurally-specific reagents and tools to cell biological studies. Relevance to public health: In the initial stages of atherosclerosis, the main cholesterol-carrying lipoprotein in blood, LDL, becomes oxidatively damaged (oxLDL), resulting in an attempt by cells lining the artery wall to scavenge the oxLDL and break it down. Our research is aimed at understanding why there is an accumulation of cholesterol in these cells because of their inability to efficiently break down the oxLDL and clear the released cholesterol.

描述（由申请方提供）：大量证据表明，动脉壁中巨噬细胞对氧化修饰低密度脂蛋白（oxLDL）的积累和随后的不良处理有助于动脉粥样硬化形成的初始阶段。LDL的氧化修饰涉及其组分载脂蛋白B被脂质过氧化反应的反应性降解产物（包括HNE）衍生化。通过这些醛的蛋白质加合的化学是高度复杂的，并且包括交联。当前资助期间的一个重大突破是发现巨噬细胞对oxLDL的摄取可能主要是通过CD36识别oxLDL中的氧化磷脂介导的。我们进一步发现，由磷脂的花生四烯基和亚油基链的“镜像”氧化产生的HNE样产物（及其衍生物）充当CD 36配体。进一步的研究提出了彻底的定义巨噬细胞内的oxLDL识别和积累的结构基础。最近的初步研究表明，氧化型低密度脂蛋白中的氧化成分可能不仅干扰脂蛋白的加工，而且还干扰暴露于氧化型低密度脂蛋白的巨噬细胞的胆固醇流出。下一个资助期的一个主要新目标是澄清oxLDL对胆固醇流出的抑制作用的性质。 我们的工作假设是，LDL的氧化变化有助于其摄入和巨噬细胞内的处理不足，oxLDL本身或从它发出的成分抑制胆固醇流出的一种或多种机制，所有这些共同作为泡沫细胞形成的一个重要决定因素。我们将继续定义脂氧化依赖性蛋白加合化学，包括质谱方法，以确定巨噬细胞蛋白，特别容易修改这些细胞暴露于oxLDL的结果。后一个目标将有助于持续发展的免疫化学探针的特定加合物，也有助于确定的性质，晚期加合物存在于人类动脉粥样硬化。这项新工作继续利用邻近研究机构三名研究人员的专业知识，特别是在将新型结构特异性试剂和工具应用于细胞生物学研究方面。 与公共卫生的相关性：在动脉粥样硬化的初始阶段，血液中主要的携带胆固醇的脂蛋白LDL变得氧化损伤（oxLDL），导致动脉壁细胞试图破坏oxLDL并将其分解。我们的研究旨在了解为什么这些细胞中胆固醇积累，因为它们无法有效地分解oxLDL并清除释放的胆固醇。