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: 9897648
• 负责人: DIANNA M MILEWICZ
• 金额: $ 64.03万
• 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 2023-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9897648
• 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。 充满巨噬细胞、坏死的脂核和含有血管平滑肌细胞(SMCs)的纤维帽。 广泛的研究已经确定了改变血脂水平和炎症的基因变异是如何促成 动脉粥样硬化，但关于影响SMC的基因改变如何易患动脉粥样硬化知之甚少。 斑块中的SMC丢失SMC的发现引发了SMC在动脉粥样硬化病变中作用的扩大 分化标志物并启动巨噬细胞标志物的表达，从而成为巨噬细胞样细胞。 类似地，SMC在体外下调SMC标记，但在暴露于SMC后上调巨噬细胞标记 不含胆固醇。我们确定了ACTA2中的一些杂合错义突变，它编码 SMC特异性α-肌动蛋白亚型易患胸主动脉疾病和早期发病 冠状动脉疾病。我们已经用一种这样的突变和SMC设计了一种小鼠模型 从Acta2R149C/+移植的主动脉在很大程度上去分化和增加巨噬细胞标志物的表达 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，并喂食高脂饮食，双突变小鼠的负担显著增加 与类似治疗的APOE-/-小鼠相比，动脉粥样硬化斑块的减少。我们假设早期发病 与SMα-肌动蛋白R149C突变相关的冠心病是由于突变的肌动蛋白折叠中断，导致 KLF4活化增强，SMC表型向巨噬细胞样细胞转化。我们进一步 推测，虽然许多ACTA2突变可能会增加SMC的增殖和迁移，但只有变体 SMC向巨噬细胞样细胞转化增加易发生早发冠心病。其目的是解决 这些假设如下：(1)表征Acta2R149C/+小鼠的动脉粥样硬化病变， 包括确定病变中SMC和巨噬细胞的来源；(2)确定细胞途径 负责增强型Acta2R149C/+SMC向暴露于胆固醇的巨噬细胞样细胞转化， 并评估这些途径在Acta2R149C/+小鼠斑块负荷增加中的作用 操纵。(3)确定与CAD相关的ACTA2突变如何通过伴侣CCT破坏折叠 复杂，并表明SMα-肌动蛋白折叠缺陷与易患冠心病的ACTA2错义之间存在因果关系 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 转换为动脉粥样硬化的危险因素，也可能确定新的治疗靶点，可以延缓或 甚至可以防止疾病的发展。