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，即I型B类清道夫受体（SR-BI），通过以下途径介导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可以 结合LDL和VLDL，并可介导细胞摄取非脂蛋白胆固醇和刺激细胞 胆固醇流出使用小鼠的体内研究，我们已经表明SR-BI在以下方面起着关键作用：1）确定 HDL的结构以及血浆HDL和胆汁胆固醇的水平，2）在介导调节递送中 高密度脂蛋白胆固醇的类固醇生成组织和肝脏，和3）防止动脉粥样硬化。上 饮食喂养的apoE敲除（KO）遗传背景（自发性动脉粥样硬化的标准鼠模型）， SR-BI基因中的纯合无效突变（SR-BI KO）引起显著加速的动脉粥样硬化。在 此外，这些双KO小鼠（“dKO”）表达在人致死性冠状动脉疾病中常见的多种特征， 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、心肌梗塞等。 梗塞（MI）、心脏功能障碍和肥大、泵衰竭和过早死亡（5-8周龄， 6周时死亡率50%）。将各种转基因或靶向基因缺失杂交到dKO小鼠中或治疗 他们与药理学药物有助于阐明冠心病的机制，并提供了 额外的证据表明该系统可以作为人类CHD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（ApoeR 61-h/h）的小鼠，我们产生SR-BI KO/ApoeR 61-h/h小鼠 当喂食普通饲料时，这些血管似乎正常，但当喂食致动脉粥样硬化（“Paigen”）饲料时，这些血管发生致命性闭塞， CHD与普通饲料喂养的dKO小鼠几乎相同（开始给药后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）。分析这两种小鼠CHD模型， 机制的见解和新的治疗或预防策略的初步分析平台。 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/ApoeR 61-h/h小鼠中，并评估和提高这些小鼠作为模型的有效性 人CHD，和II）使用体细胞遗传学在细胞水平鉴定基因产物，和 这些功能是SR-BI活动所必需的，是SR-BI对心血管系统的深刻影响的基础。 系统广泛的分子、细胞、生理、成像、遗传、基因组和药理学 这些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爱马仕的系统， 广播和分析真实的时间连续EGG测量从非常年轻的（因此小） 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） 表达和心脏形态。我们将与第二和第五项目合作，评估以下方面的作用： 粘附分子、血小板及止血、炎症对冠心病的影响; 3）用项目III探讨 关键能量代谢激素脂联素对冠心病的作用，以及4）与项目III一起使用逆转录病毒 技术和体细胞遗传学来鉴定SR-BI活性所需的细胞基因。当我们确定 体细胞遗传学的其他基因可能是心血管疾病的重要贡献者， 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）我们目前的和遗传改良的基于SR-BI的鼠 系统是人类CHD的有效模型，可用于阐明疾病的潜在机制， 和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 这项工作应该有助于阐明心血管功能的关键生物学机制， 病理生理学