ApoE receptor-2 in vascular disease progression and regression

apoE 受体 2 (apoER2) 编码基因 LRP8 是早发动脉粥样硬化和早发性动脉粥样硬化的主要基因位点。 急性心肌梗塞。一种具有 R952Q 突变（等位基因频率 0.29）的 apoER2 变体与 急性心肌梗塞的风险增加2-4倍。 LRP8多态性与LRP8的关系 心血管疾病风险与血浆胆固醇水平无关，但与 apoER2 相关的病因学 心血管疾病的功能障碍尚不清楚。该应用的前提是apoER2功能障碍 损害平滑肌和树突状细胞功能，对动脉粥样硬化进展产生不利影响 回归。我们之前已经证明，高脂血症 Ldlr-/- 小鼠中 apoER2 缺乏会加速 动脉粥样硬化病变坏死。 ApoER2 缺陷也会促进细胞贫乏但富含纤维化的细胞的形成 内皮剥脱后出现新内膜，提示过度衰老相关的分泌平滑肌 肌肉细胞。其他体外数据显示 apoER2 与蛋白质的催化亚基相互作用 平滑肌细胞中的磷酸酶 2 (PP2A-C)，其缺失会损害中期阶段的 PP2A-C 功能 后期转变，从而导致细胞周期停滞、有丝分裂滑移和细胞过早衰老。 其他初步研究还发现 CD11c 树突状细胞中 apoER2 表达及其缺陷导致 粘斑蛋白 VASP 的持续磷酸化以及迁移和迁移受损 胞吞作用。该项目的目标之一是建立细胞表面受体如何作用的机制框架 apoER2 调节平滑肌细胞和树突状细胞中的这些细胞内事件。另一个目标是测试 CD11c 树突状细胞中的 apoER2 功能障碍阻碍病变消退并发挥作用的假设 与apoER2缺陷的平滑肌细胞协同作用，加速病灶坏死。机理研究 目标 1 中提出的问题将询问细胞表面受体结合/回收和信号传导是否足够，或者是否 有效平滑肌需要生成 apoER2 细胞内胞质结构域 (ICD) 肽 细胞胞质分裂和树突状细胞胞吞作用和迁移。目标2将比较apoER2的影响 细胞质剪接变异以及 R952Q 突变如何影响 apoER2 对纤维化新生内膜的保护 高脂血症中内皮剥脱后的形成和晚期动脉粥样硬化病变的发展 Ldlr-/- 小鼠。目标 3 将使用组织特异性 Lrp8 敲除小鼠以及骨髓移植方法 检验 CD11c 树突状细胞中 apoER2 功能障碍会降低动脉粥样硬化能力的假设 病变消退并与平滑肌 apoER2 缺乏症协同作用，加速动脉粥样硬化 病灶坏死。这些研究将提供新的机制来描述细胞表面受体 apoER2 如何 调节与细胞分裂和运动相关的细胞内事件，从而影响心血管疾病。的 信息还可用于设计对抗心血管疾病的个性化治疗策略 在大量个体中存在Lrp8基因多态性和突变。

The apoE receptor-2 (apoER2) encoding gene LRP8 is a major gene locus for premature atherosclerosis and acute myocardial infarction. One apoER2 variant with the R952Q mutation (allele frequency 0.29) is associated with a 2-4 fold increase risk of acute myocardial infarction. The relationship between LRP8 polymorphism and cardiovascular disease risk is independent of plasma cholesterol levels, but the etiology associating apoER2 dysfunction with cardiovascular disease is unknown. The premise of this application is that apoER2 dysfunctions impair smooth muscle and dendritic cell functions to adversely influence atherosclerosis progression and regression. We have shown previously that apoER2 deficiency in hyperlipidemic Ldlr-/- mice accelerates atherosclerotic lesion necrosis. ApoER2 deficiency also promotes formation of cell-poor but fibrotic-rich neointima after endothelial denudation, suggestive of excessive senescence-associated secretory smooth muscle cells. Additional in vitro data revealed that apoER2 interacts with the catalytic subunit of protein phosphatase 2 (PP2A-C) in smooth muscle cells, and its absence impairs PP2A-C functions during metaphase- anaphase transition, thereby causing cell cycle arrest, mitotic slippage, and premature cell senescence. Additional preliminary studies also found apoER2 expression in CD11c+ dendritic cells and its deficiency leads to persistent phosphorylation of the focal adhesion protein VASP and the impairment of migration and efferocytosis. One goal of this project is to establish a mechanistic framework of how the cell surface receptor apoER2 modulates these intracellular events in smooth muscle cells and dendritic cells. Another goal is to test the hypothesis that apoER2 dysfunction in CD11c+ dendritic cells impedes lesion regression and works synergistically with apoER2-deficient smooth muscle cells to accelerate lesion necrosis. Mechanistic studies proposed in Aim 1 will interrogate whether cell surface receptor binding/recycling and signaling is sufficient or if generation of an apoER2 intracellular cytoplasmic domain (ICD) peptide is required for efficient smooth muscle cell cytokinesis and dendritic cell efferocytosis and migration. Aim 2 will compare the influence of apoER2 cytoplasmic splice variants and how the R952Q mutation impact on apoER2 protection against fibrotic neointimal formation after endothelial denudation and advanced atherosclerotic lesion development in hyperlipidemic Ldlr-/- mice. Aim 3 will use tissue-specific Lrp8 knockout mice as well as bone marrow transplant approach to test the hypothesis that apoER2 dysfunction in CD11c+ dendritic cells reduces the capacity for atherosclerosis lesion regression and act synergistically with smooth muscle apoER2 deficiency to accelerate atherosclerotic lesion necrosis. These studies will offer novel mechanisms depicting how the cell surface receptor apoER2 modulates intracellular events associated with cell division and motility to impact cardiovascular disease. The information may also be leveraged to design personalized therapeutic strategy to combat cardiovascular disease in a large number of individuals with Lrp8 gene polymorphism and mutation.