Lipoproteins in Cardiovascular Biology and Pathology

心血管生物学和病理学中的脂蛋白

• 批准号: 7217664
• 负责人: MONTY KRIEGER
• 金额: $ 42.9万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7217664
• 关键词: adiponectin; bioenergetics; cell adhesion; coronary disorder; disease /disorder model; gene expression; genetically modified animals; heart failure; hemostasis; high density lipoproteins; inflammation; laboratory mouse; lipid transport; microRNAs; platelets; protein transport; receptor; transfection /expression vector

The HDL receptor, scavenger receptor class B type I (SR-BI), mediates cellular delivery of HDL cholesterol by selective lipid uptake, a mechanism distinct from classic receptor-mediated endocytosis. In addition, SR-BI can bind LDL and VLDL and can mediate both cellular uptake of non-lipoprotein cholesterol and stimulate cellular cholesterol efflux. Using in vivo studies with mice, we have shown that SR-BI plays a key role 1) in determining the structure of HDL and levels of both plasma HDL and biliary cholesterol, 2) in mediating the regulated delivery of HDL-cholesterol to steroidogenic tissues and the liver, and 3) in protecting against atherosclerosis. On a chow-fed apoE knockout (KO) genetic background (standard murine model of spontaneous atherosclerosis), homozygous null mutations in the SR-BI gene (SR-BI KO) cause dramatically accelerated atherosclerosis. In addition, these double KO mice ('dKO') express multiple characteristics commonly seen in human fatal coronary heart disease (CHD) and heart failure, including hypercholesterolemia, occlusive atherosclerosis, myocardial infarction (Ml), cardiac dysfunction and hypertrophy, pump failure and premature death (5-8 weeks of age, 50% mortality at 6 weeks). Crossing various transgenes or targeted gene deletions into dKO mice or treating them with pharmacologic agents is helping to elucidate the mechanisms underlying CHD and has provided additional evidence that this system may serve as a powerful model for human CHD. By crossing SR-BI single KO mice with mice carrying a hypomorphic apoE allele (ApoeR61-h/h), we generated SR-BI KO/ApoeR61-h/h mice that appear normal when fed a chow diet, but when fed an atherogenic ('Paigen') diet develop fatal occlusive CHD that is virtually identical to that in chow-fed dKO mice (50% mortality 32+/-6 days after initiation of the atherogenic diet). Withdrawal of the atherogenic diet can be used to study regression/recovery of disease (atherosclerosis, Ml, heart failure). Analysis of these two murine models of CHD should provide new mechanistic insights and a platform for preliminary analysis of new treatment or prevention strategies. The twin goals of this Project are I) to characterize the mechanisms underlying early onset CHD and death in dKO and SR-BI KO/ApoeR61-h/h mice and assess and improve the validity of these mice as models for human CHD, and II) to use somatic cell genetics to identify at the cellular level the gene products and functions that are required for SR-BI activity and underlie SR-BI's profound effects on the cardiovascular system. A wide array of molecular, cellular, physiologic, imaging, genetic, genomic and pharmacologic approaches will be used in close conjunction with the other Projects and Cores. For example, 1) with the Murine Genetics and Physiology Core we will continue to develop a system called HERMES to acquire, web broadcast and analyze in real time continuous EGG measurements from the very young (and thus small) dKO mice, which will allow us to correlate cardiac function with biochemistry, gene (including microRNA) expression and cardiac morphology. We will collaborate 2) with Projects II and V to evaluate the roles of adhesion molecules, platelets and hemostasis, and inflammation on CHD, 3) with Project III to explore the role of the key energy metabolism hormone adiponectin on CHD, and 4) with Project III in using retroviral technologies and somatic cell genetics to identify cellular genes required for SR-BI activity. As we identify additional genes by somatic cell genetics that are potentially significant contributors to cardiovascular pathophysiology, we will assess the contributions of genetic variation in these genes to clinical phenotypes. We will test the hypotheses that 1) our current and genetically improved SR-BI-based murine systems are valid models for human CHD and can be used to elucidate mechanisms underlying disease, and 2) identification of genes required for SR-BI function in cultured cells will help uncover both SR-BI-specific and globally important mechanisms of membrane protein processing and function. The proposed work should help elucidate key biological mechanisms underlying cardiovascular function and pathophysiology.

HDL 受体，B 型清道夫受体 I 型 (SR-BI)，通过以下方式介导 HDL 胆固醇的细胞递送： 选择性脂质摄取，一种不同于经典受体介导的内吞作用的机制。此外，SR-BI 还可以 结合 LDL 和 VLDL，可以介导细胞对非脂蛋白胆固醇的摄取并刺激细胞 胆固醇外流。通过对小鼠进行体内研究，我们发现 SR-BI 在 1) 确定中发挥着关键作用 HDL 的结构以及血浆 HDL 和胆汁胆固醇的水平，2) 介导调节输送 HDL-胆固醇对类固醇生成组织和肝脏的影响，3) 预防动脉粥样硬化。上一个 饲料喂养的 apoE 敲除 (KO) 遗传背景（自发性动脉粥样硬化的标准小鼠模型）， SR-BI 基因的纯合无效突变（SR-BI KO）会导致动脉粥样硬化急剧加速。在 此外，这些双敲除小鼠（“dKO”）表现出人类致命性冠状动脉中常见的多种特征 心脏病（CHD）和心力衰竭，包括高胆固醇血症、闭塞性动脉粥样硬化、心肌病 梗塞（MI）、心脏功能障碍和肥厚、泵衰竭和过早死亡（5-8周龄、 6 周时死亡率为 50%）。将各种转基因或靶向基因缺失杂交到 dKO 小鼠中或进行治疗 他们与药物制剂的结合有助于阐明 CHD 的潜在机制，并提供了 更多证据表明该系统可以作为人类冠心病的强大模型。通过交叉SR-BI单 KO 小鼠与携带亚型 apoE 等位基因 (ApoeR61-h/h) 的小鼠，我们生成 SR-BI KO/ApoeR61-h/h 小鼠 当喂食食物时，这些细胞看起来正常，但当喂食致动脉粥样硬化（“Paigen”）饮食时，会出现致命的闭塞 CHD 与食物喂养的 dKO 小鼠几乎相同（开始治疗后 32+/-6 天死亡率为 50%） 致动脉粥样硬化饮食）。停止致动脉粥样硬化饮食可用于研究疾病的消退/恢复 (动脉粥样硬化、MI、心力衰竭)。对这两种小鼠先心病模型的分析应该提供新的 机制见解和新治疗或预防策略初步分析的平台。 该项目的双重目标是 I) 描述早发冠心病和死亡的潜在机制 在 dKO 和 SR-BI KO/ApoeR61-h/h 小鼠中进行研究，并评估和提高这些小鼠作为模型的有效性 人类冠心病，以及 II) 使用体细胞遗传学在细胞水平上鉴定基因产物和 SR-BI 活性所需的功能以及 SR-BI 对心血管产生深远影响的基础 系统。广泛的分子、细胞、生理、成像、遗传、基因组和药理学 方法将与其他项目和核心紧密结合使用。例如，1）与 小鼠遗传学和生理学核心，我们将继续开发一个名为 HERMES 的系统来获取、网络 实时广播和分析来自很小的孩子（因此很小）的连续 EGG 测量结果 dKO 小鼠，这将使我们能够将心脏功能与生物化学、基因（包括 microRNA）相关联 表达和心脏形态。我们将与项目 II 和 V 合作 2) 评估 粘附分子、血小板和止血以及 CHD 的炎症，3) 与 Project III 一起探索 关键能量代谢激素脂联素对 CHD 的作用，以及 4) 项目 III 使用逆转录病毒 技术和体细胞遗传学来识别 SR-BI 活性所需的细胞基因。正如我们所确定的 体细胞遗传学的其他基因可能对心血管有重要影响 病理生理学，我们将评估这些基因的遗传变异对临床的贡献 表型。我们将测试以下假设：1) 我们当前的和基于 SR-BI 的基因改良小鼠 系统是人类冠心病的有效模型，可用于阐明疾病的机制， 2) 鉴定培养细胞中 SR-BI 功能所需的基因将有助于揭示 SR-BI 特异性 以及膜蛋白加工和功能的全球重要机制。拟议的 工作应有助于阐明心血管功能和潜在的关键生物学机制 病理生理学。