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，清道夫受体B类I类（SR-BI）介导HDL胆固醇的细胞递送 选择性脂质摄取，这是一种与经典受体介导的内吞作用不同的机制。另外，SR-BI可以 结合LDL和VLDL，可以介导非脂蛋白胆固醇的细胞摄取并刺激细胞 胆固醇外排。使用小鼠体内研究，我们表明SR-BI在确定中起关键作用1） HDL的结构以及血浆HDL和胆汁胆固醇的水平，2）介导调节递送 HDL-胆固醇与类固醇组织和肝脏的抗体，3）防止动脉粥样硬化。在 杂志喂养的Apoe敲除（KO）遗传背景（自发动脉粥样硬化的标准鼠模型）， SR-BI基因（SR-BI KO）中的纯合无效突变引起大幅加速的动脉粥样硬化。在 此外，这些双重KO小鼠（'dko'）表达了在人类致命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 梗塞（ML），心脏功能障碍和肥大，泵衰竭和过早死亡（5-8周龄，年龄， 6周时死亡率为50％）。将各种转基因或靶向基因缺失跨到DKO小鼠或治疗 他们与药理学剂一起有助于阐明冠心病的机制，并提供了 其他证据表明该系统可能是人类冠心病的强大模型。通过越过SR-BI单 KO小鼠的小鼠携带肌肌apoE等位基因（ApoER61-H/h），我们产生了SR-BI KO/Apoer61-H/H小鼠 喂食饮食时看起来很正常 冠心病与乔喂养的DKO小鼠几乎相同（在开始启动后32 +/- 6天死亡率32 +/- 动脉粥样硬化饮食）。戒断饮食可用于研究疾病的回归/恢复 （动脉粥样硬化，ML，心力衰竭）。分析这两种CHD的鼠模型应提供新的 机械洞察力和新疗法或预防策略初步分析的平台。 该项目的双目标是i）表征早期发作和死亡的机制 在DKO和SR-BI KO/APOER61-H/H小鼠中，并评估并提高了这些小鼠的有效性作为模型 人冠心，ii）使用体细胞遗传学在细胞水平上鉴定基因产物和 SR-BI活动所需的功能和SR-BI对心血管的深刻影响 系统。各种各样的分子，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密切结合使用。例如，1） 鼠类遗传学和生理核心我们将继续开发一个名为爱马仕的系统以获取，网络 从非常年轻的（因此很小）的实时连续鸡蛋测量进行广播和分析 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，以及冠心病上的炎症，3）与项目III一起探索 关键能量代谢激素脂联素在CHD上的作用，以及使用逆转录病毒的项目III的作用4） 鉴定SR-BI活性所需的细胞基因的技术和体细胞遗传学。当我们确定 体细胞遗传学的其他基因可能是心血管造成的重要重要因素 病理生理学，我们将评估这些基因遗传变异对临床的贡献 表型。我们将测试以下假设，即1）我们的电流和基于遗传改善的SR-BI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发现两个SR-BI特异性 以及膜蛋白质加工和功能的全球重要机制。提议 工作应有助于阐明心血管功能的关键生物学机制和 病理生理学。