Mechanisms by which LRP1 Protects the Vasculature

LRP1 保护脉管系统的机制

• 批准号: 8722143
• 负责人: Dudley K. Strickland
• 金额: $ 38.38万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-04 至 2018-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8722143
• 关键词: Abdominal Aortic Aneurysm; Accounting; Acute; Affect; Amino Acid Substitution; Aneurysm; Aorta; Aortic Aneurysm; Aortic Diseases; Atherosclerosis; Binding; Biochemical; Blood - brain barrier anatomy; Blood Vessels; Cells; Cessation of life; Chest; Chymase; Clinical Data; Collaborations; Collagen; Coronary; Country; DNA; Data; Deposition; Development; Dideoxy Chain Termination DNA Sequencing; Dilatation - action; Disease; Dissection; Elastic Fiber; Elastin; Elderly; Event; Extracellular Matrix; Family; Family member; Filament; Gene Mutation; Genes; Genetic; Genetic Determinism; Heart; High temperature of physical object; Human; Inflammatory; Inherited; Intervention; LDL-Receptor Related Protein 1; Lead; Ligand Binding; Mediating; Modeling; Molecular; Mus; Muscle Contraction; Mutation; Operative Surgical Procedures; Orthologous Gene; Pathway interactions; Patients; Peptide Hydrolases; Phenotype; Physiological Processes; Physiology; Plant Roots; Plasma; Predisposition; Process; Proteins; Proteomics; Receptor Signaling; Role; Rupture; Signal Pathway; Signal Transduction; Smooth Muscle Myocytes; Symptoms; Testing; Thoracic Aortic Aneurysm; Variant; Vascular Proliferation; Vascular Smooth Muscle; age group; exome sequencing; genome wide association study; human disease; in vivo; inhibitor/antagonist; macrophage; mast cell protease 4; prevent; public health relevance; rare variant; receptor; receptor function; research study

Aortic aneurysms and aortic dissections account for 1% to 2% of all deaths in Western countries, and are usually asymptomatic until they rupture which most often results in death. Unfortunately, our current understanding of the molecular mechanisms leading to aneurysm formation is limited. Genome wide association studies reveal that the Lrp1 gene represents a susceptibility locus for abdominal aortic aneurysms. LRP1 encodes the LDL receptor related protein 1 (LRP1), a large endocytic and signaling receptor that regulates important physiological processes. Our recent studies reveal that mice in which the Lrp1 gene is selectively deleted in smooth muscle cells (smLRP1-/- mice) develop thoracic aneurysms. These mice display all of the symptoms detected in the human disease, including extensive in vivo aortic root and thoracic aortic dilatation, elastic lamina disorganization, recruitment of inflammatory cells into the vessel wall and excess collagen deposition. Proteomic studies revealed accumulation of proteases in the vessel wall, including HtrA1 (high-temperature requirement factor A1) and mast cell protease 4 (mMCP-4), the murine ortholog of human chymase. Both of these proteases are involved in matrix and elastic lamina degradation. Studies in Aim 1 will test the hypothesis that SMC LRP1 protects the vasculature by modulating protease activity, especially HtrA1 and mMCP-4, which in turn regulates the integrity of the elastic laminae. Ultrastructure studies of the aortic wall in smLRP1-/- mice reveal abnormal SMC. The TGF signaling pathway is a major pathway that is responsible for maintaining SMC in a contractile phenotype, and our preliminary data reveal that LRP1 binds several TGF family members and is required for the non-canonical signaling mediated by TGF Experiments in Aim 2 will test the hypothesis that LRP1 modulates SMC phenotypic transitions by regulating the TGF signaling pathway. Finally, we have initiated studies in collaboration with Dianna Milewicz (UT Houston) who has performed exome and Sanger sequencing of DNA from families with thoracic aortic aneurysms and acute aortic dissections. These studies identified several extremely rare LRP1 variants that segregate with aortic disease in these families, providing strong evidence that they are associated with the disease. Analysis of the amino acid substitutions in several of these variants suggest a strong rational for altered ligand binding and altered function in LRP1. Studies in Aim 3 will test the hypothesis that these rare variants result in defective LRP1 function, which in turn contributes to the development of this disease.

在西方国家，主动脉瘤和主动脉夹层占所有死亡的1%至2%。 在一些国家，通常无症状，直到破裂，最常导致死亡。 不幸的是，我们目前对导致动脉瘤的分子机制的理解 形成有限。全基因组关联研究表明，Lrp 1基因代表了一种 腹主动脉瘤的易感部位LRP 1编码LDL受体相关的 蛋白1（LRP 1），一种大的内吞和信号传导受体，调节重要的生理功能， 流程.我们最近的研究表明，Lrp 1基因选择性缺失的小鼠， 平滑肌细胞（smLRP 1-/-小鼠）发生胸动脉瘤。这些老鼠展示了 在人类疾病中检测到的症状，包括广泛的体内主动脉根， 胸主动脉扩张，弹性膜破坏，炎性细胞聚集， 血管壁和过量胶原沉积。蛋白质组学研究显示， 血管壁中的蛋白酶，包括HtrA 1（高温需要因子A1）和肥大细胞 细胞蛋白酶4（mMCP-4），人糜蛋白酶的鼠直系同源物。这两种蛋白酶都是 参与基质和弹性膜降解。目标1中的研究将检验以下假设： SMC LRP 1通过调节蛋白酶活性，特别是HtrA 1和HtrB 1， mMCP-4，其反过来调节弹性膜的完整性。超微结构研究 smLRP 1-/-小鼠主动脉壁显示异常SMC。TGF信号通路是一种 主要途径，负责维持SMC的收缩表型，我们的研究表明， 初步数据显示，LRP 1与几个TGF家族成员结合，是TGF-β 1表达所必需的。 目标2中TGF-β介导的非典型信号传导实验将检验以下假设： LRP 1通过调节TGF信号通路调节SMC表型转变。 最后，我们与Dianna Milewicz（UT Houston）合作开展了研究， 对胸主动脉瘤家系进行外显子组和桑格测序 和急性主动脉夹层这些研究确定了几种极其罕见的LRP 1变体， 在这些家庭中与主动脉疾病隔离，提供了强有力的证据表明他们是 与疾病有关。分析其中几个中的氨基酸取代， 变体表明LRP 1中改变的配体结合和改变的功能的强合理性。 目标3中的研究将检验这些罕见变异导致LRP 1缺陷的假设。 功能，这反过来又有助于这种疾病的发展。