Novel genetic Insight into the molecular pathogenesis of atherosclerosis

动脉粥样硬化分子发病机制的新遗传学见解

• 批准号: 10360600
• 负责人: DIANNA M MILEWICZ
• 金额: $ 64.05万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-01 至 2024-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10360600
• 关键词: Actins; Acute; Address; Affect; Aorta; Aortic Diseases; Apolipoprotein E; Arterial Fatty Streak; Atherosclerosis; Bone Marrow; Bone Marrow Transplantation; Carotid Arteries; Cell Proliferation; Cells; Chest; Cholesterol; Chronic; Complex; Coronary Arteriosclerosis; Defect; Differentiation Antigens; Disease Progression; Dissection; Engineering; Etiology; Exposure to; GKLF protein; Genetic; High Fat Diet; In Vitro; Individual; Inflammation; Inflammatory; Knock-in; Knock-in Mouse; Lead; Lesion; Lipids; Missense Mutation; Modeling; Molecular; Morbidity - disease rate; Mus; Muscle Proteins; Mutant Strains Mice; Mutation; Necrosis; Onset of illness; Pathogenesis; Pathway interactions; Phenotype; Polymers; Proliferating; Protein Isoforms; Research; Risk; Risk Factors; Role; Smooth Muscle; Smooth Muscle Myocytes; Testing; Thin Filament; Thoracic Aortic Aneurysm; Variant; Vascular Diseases; Vascular Smooth Muscle; Work; alpha Actin; atherosclerosis risk; cell motility; chaperonin CCT; early onset; experimental study; genetic manipulation; genetic variant; insight; macrophage; monomer; mortality; mouse model; mutant; new therapeutic target; novel; prevent; therapeutic target; transcriptome

Atherosclerosis is a chronic inflammatory condition characterized by arterial plaques composed of cholesterol- filled macrophages, a necrotic lipid core, and a fibrous cap containing vascular smooth muscle cells (SMCs). Extensive work has defined how genetic variants altering lipid levels and inflammation contribute to atherosclerosis, but less is known as to how genetic alterations affecting SMCs predispose to atherosclerosis. An expanded role for SMCs in atherosclerotic lesions is evoked by the finding that SMCs in plaques lose SMC differentiation markers and initiate expression of macrophage markers, thus becoming a macrophage-like cell. Similarly, SMCs downregulate SMC markers in vitro, but upregulate macrophage markers with exposure to free cholesterol. We determined that some heterozygous missense mutations in ACTA2, which encodes the SMC-specific isoform of α-actin, predispose individuals to both thoracic aortic disease and early onset coronary artery disease (CAD). We have engineered a mouse model with one such mutation and SMCs explanted from Acta2R149C/+ aortas de-differentiate and increase expression of macrophage markers at much lower concentrations of free cholesterol than wildtype SMCs. Furthermore, when the Acta2R149C/+ mice are crossed into Apoe-/- mice and fed a high fat diet, the double mutant mice have a significantly increased burden of atherosclerotic plaques when compared to similarly treated Apoe-/- mice. We hypothesize that early onset CAD associated with the SM α-actin R149C mutation is due to disrupted folding of the mutant actin, leading to increased Klf4 activation and augmented SMC phenotypic switching to macrophage-like cells. We further speculate that, although many ACTA2 mutations may increase SMC proliferation and migration, only variants that increase SMC switching to macrophage-like cells will predispose to early onset CAD. The aims to address these hypotheses are the following: (1) Characterize the atherosclerotic lesions in the Acta2R149C/+ mice, including identifying the origin of the SMCs and macrophages in the lesions; (2) Identify cellular pathways responsible for enhanced Acta2R149C/+ SMC switching to a macrophage-like cell with exposure to cholesterol, and assess the role of these pathways in the increased plaque burden in Acta2R149C/+ mice through genetic manipulation. (3) Determine how CAD-associated ACTA2 mutations disrupt folding by the chaperonin CCT complex, and show causality between SM α-actin folding defects and CAD-predisposing ACTA2 missense mutations. Thus, the proposed research will provide valuable new insights into the role of SMC phenotypic switching as a risk factor for atherosclerosis, and may also identify novel therapeutic targets that can delay or even prevent disease progression.

动脉粥样硬化是一种慢性炎症性疾病，其特征是动脉斑块由胆固醇组成 充满的巨噬细胞、坏死的脂质核心和含有血管平滑肌细胞（SMC）的纤维帽。 大量的工作已经确定了基因变异如何改变脂质水平和炎症导致 动脉粥样硬化，但对于影响 SMC 的基因改变如何导致动脉粥样硬化却知之甚少。 斑块中 SMC 失去 SMC 的发现引发了 SMC 在动脉粥样硬化病变中的扩大作用 分化标记并启动巨噬细胞标记的表达，从而成为巨噬细胞样细胞。 同样，SMC 在体外下调 SMC 标记，但在暴露于 游离胆固醇。我们确定 ACTA2 中存在一些杂合错义突变，该突变编码 SMC 特异性 α-肌动蛋白亚型，使个体易患胸主动脉疾病和早发型 冠状动脉疾病（CAD）。我们设计了一种具有此类突变和 SMC 的小鼠模型 从 Acta2R149C/+ 移植的主动脉去分化并增加巨噬细胞标记物的表达 游离胆固醇浓度低于野生型 SMC。此外，当 Acta2R149C/+ 小鼠 与 Apoe-/- 小鼠杂交并喂食高脂肪饮食，双突变小鼠的负担显着增加 与经过类似处理的 Apoe-/- 小鼠相比，动脉粥样硬化斑块的减少。我们假设早发 与 SM α-肌动蛋白 R149C 突变相关的 CAD 是由于突变肌动蛋白的折叠被破坏，导致 增加 Klf4 激活并增强 SMC 表型转换为巨噬细胞样细胞。我们进一步 推测，虽然许多 ACTA2 突变可能会增加 SMC 增殖和迁移，但只有变体 增加 SMC 向巨噬细胞样细胞的转化将导致早发 CAD。目的是解决 这些假设如下：（1）表征 Acta2R149C/+ 小鼠的动脉粥样硬化病变， 包括识别病变中 SMC 和巨噬细胞的起源； (2) 识别细胞通路 负责增强 Acta2R149C/+ SMC 在暴露于胆固醇的情况下转换为巨噬细胞样细胞， 并通过遗传评估这些途径在 Acta2R149C/+ 小鼠斑块负荷增加中的作用 操纵。 (3) 确定 CAD 相关的 ACTA2 突变如何破坏伴侣蛋白 CCT 的折叠 复杂，并显示 SM α-肌动蛋白折叠缺陷与 CAD 易感性 ACTA2 错义之间的因果关系 突变。因此，拟议的研究将为 SMC 表型的作用提供有价值的新见解。 转换作为动脉粥样硬化的危险因素，并且还可能确定可以延迟或延迟的新治疗靶点 甚至阻止疾病进展。