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

基本信息

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
项目类别：
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

项目摘要

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疾病，其特征是由胆固醇组成的动脉斑块填充的巨噬细胞，坏死脂质芯和含有血管平滑肌细胞（SMC）的纤维帽。广泛的工作已经定义了如何改变脂质水平和注射的遗传变异动脉粥样硬化，但鲜为人知的是如何影响SMC的遗传变化对动脉粥样硬化的易感性。 SMC在斑块中丢失SMC的发现唤起了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，从而成为巨噬细胞样细胞。同样，SMC在体外下调SMC标记，但在暴露于免费胆固醇。我们确定Acta2中的一些杂合错义突变，该突变编码 α-肌动蛋白的SMC特异性同工型，易感性个体均对胸部主动脉疾病和早期发作冠状动脉疾病（CAD）。我们已经设计了一种具有这样突变和SMC的鼠标模型从ACTA2R149C/+主动脉脱离分化并增加巨噬细胞标记的表达比野生型SMC浓度低的游离胆固醇。此外，当acta2r149c/+小鼠是双重突变小鼠越过Apoe - / - 小鼠并喂养高脂肪饮食，燃烧明显增加与经过类似处理的APOE - / - 小鼠相比，动脉粥样硬化斑块的斑块。我们假设早期发作与SMα-肌动蛋白R149C突变相关的CAD是由于突变肌动蛋白的折叠而导致的，导致 KLF4激活增加并增强了SMC表型转换为巨噬细胞样细胞。我们进一步推测，尽管许多ACTA2突变可能会增加SMC的增殖和迁移，但只有变体这种增加的SMC切换到巨噬细胞样细胞会易于早期发作CAD。解决的目的这些假设如下：（1）表征ACTA2R149C/+小鼠中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）确定细胞途径负责增强的ACTA2R149C/+ SMC切换到类似巨噬细胞的细胞，暴露于胆固醇，并通过遗传评估这些途径在ACTA2R149C/+小鼠中增加的斑块伯嫩中的作用操纵。（3）确定与CAD相关的ACTA2突变如何破坏伴侣蛋白CCT的折叠复合物，并显示SMα-肌动蛋白折叠缺陷与CAD-PREDISPOSIDAS ACTA2错过之间的因果关系突变。这是拟议的研究将为SMC表型的作用提供宝贵的新见解切换为动脉粥样硬化的危险因素，还可以识别出可能延迟或甚至预防疾病进展。