Role of CHF1 in Occlusive Vascular Disease

描述（由申请人提供）：血管平滑肌细胞从分化、收缩到增生、迁移和合成表型的转变被认为是闭塞性血管病变发展的重要因素。调控这种表型转变的遗传开关尚未完全被理解。我们之前已经发现CHF1，一种在心血管系统中表达的bHLH转录因子，是室间隔和功能的重要调节因子。我们假设该蛋白也是血管平滑肌细胞（VSMC）功能在血管疾病发展中的关键调节因子。我们从CHF1基因敲除小鼠中获得的初步数据支持了这一假设，因为这些小鼠在血管损伤后新内膜形成减少，并且这些小鼠的VSMCs在血小板衍生生长因子（PDGF）和肝素结合表皮生长因子（HB-EGF）的作用下迁移减少。分子缺陷至少部分涉及到Racl活化的衰减。我们的具体目标是：目标1：表征缺乏CHF1的VSMCs的分子表型，并确定对生长因子反应性降低的基础。我们将测量PDGF和HB-EGF信号通路中已知组分的表达和激活，最初将重点关注Racl活性的调节因子。我们还将在PDGF刺激后的不同时间点对野生型和敲除型细胞进行基因组分析。目的2：生成血管平滑肌特异性缺乏CHF1的条件型CHF1 KO小鼠。目前尚不清楚CHF1 KO小鼠损伤后新生内膜减少是由于局部血管平滑肌、内皮、循环干细胞的影响，还是通过多种细胞类型的组合。为了解决这个问题，我们将产生血管壁平滑肌层特异性缺乏CHF1的条件敲除小鼠，然后评估它们对血管损伤的反应。目的3：探讨血管平滑肌细胞CHF1缺乏对实验性动脉粥样硬化的影响。我们假设chfl介导的血管平滑肌效应对动脉粥样硬化病变的发展至关重要。我们将血管平滑肌中缺乏CHF1的条件敲除小鼠与ApoE缺失的小鼠杂交，并测量双敲除小鼠动脉粥样硬化病变的发展。

DESCRIPTION (provided by applicant): The transition of vascular smooth muscle cells from a differentiated, contractile to a proliferative, migratory and synthetic phenotype is hypothesized to be important in the development of occlusive vascular lesions. The genetic switches that regulate this phenotypic transition are not completely understood. We have previously identified CHF1, a bHLH transcription factor expressed in the cardiovascular system, as an important regulator of ventricular septation and function. We hypothesize that this protein is also a critical regulator of vascular smooth muscle cell (VSMC) function in the development of vascular disease. Our preliminary data from CHF1 knockout mice support this hypothesis, in that these mice show decreased neointimal formation after vascular injury, and that VSMCs from these mice show decreased migration in response to platelet derived growth factor (PDGF) and heparin binding epidermal growth factor (HB-EGF). The molecular defect at least partially involves attenuation of Racl activation. Our specific aims are: Aim 1: Characterize the molecular phenotype of VSMCs lacking CHF1 and determine the basis for decreased responsiveness to growth factors We will measure expression and activation of known components of the PDGF and HB-EGF signaling pathways, focusing initially on regulators of Racl activity. We will also perform a genomic analysis of wild type and knockout cells at varying time points after PDGF stimulation. Aim 2: Generate conditional CHF1 KO mice lacking CHF1 specifically in vascular smooth muscle. At present, it is unclear whether decreased neointima after injury in CHF1 KO mice is due to effects on local vascular smooth muscle, endothelium, circulating stem cells, or through a combination of cell types. To address this question, we will generate conditional knockout mice that lack CHF1 specifically in the smooth muscle layer of the vessel wall and then assess their response to vascular injury. Aim 3: Measure the effect of vascular smooth muscle cell CHF1 deficiency on experimental atherosclerosis. We hypothesize that CHFl-mediated effects on vascular smooth muscle are essential for the development of atherosclerotic lesions. We will cross conditional knockout mice lacking CHF1 in vascular smooth muscle with ApoE null mice and measure the development of atherosclerotic lesions in the double knockout mice.