Coordinated Control of Vascular SMC Growth & Fibrogeneni

血管平滑肌细胞(SMCs)是动脉的主要细胞成分，它合成大量的血管壁结缔组织，包括弹性蛋白、I型和V/XI型胶原纤维。在损伤和某些疾病状态下，如动脉粥样硬化，通常静止的中膜SMC迁移到它们经历增殖的内膜，并沉积基质成分，从而促进动脉粥样硬化斑块的形成和血管闭塞。重要的是，越来越多的证据表明，斑块纤维帽的破裂会导致动脉粥样硬化的冠状动脉和颈动脉血栓栓塞症并发症。 疾病。巨细胞病毒(CMV)感染被认为是动脉粥样硬化和再狭窄的致病因素之一。PI实验室的工作导致了一种假设，即MYB和NF-kappaB家族的转录因子在协调控制基质合成和血管SMC增殖方面发挥关键作用。B-Myb可抑制培养的SMC I型和V型胶原和弹性蛋白基因转录，细胞周期蛋白A/CDK2的磷酸化可解除对α2(V)型胶原启动子的抑制。最近建立了一个携带B-MYB转基因的转基因小鼠模型；与野生型小鼠相比，转基因小鼠的主动脉和分离的SMC显示出弹性蛋白的大幅减少，胶原和赖氨酸氧化酶的mRNA表达显著减少。B-myb基因表达受SMC生长状态调控，c-Myb和A-Myb可促进血管SMC增殖。此外，CMV即刻早期(IE)1蛋白被发现选择性地诱导RelB/p50 NF-kappaB复合体，这可能控制 促进SMC增殖的基因。本文旨在阐明Myb和NF-kappaB因子在心血管疾病中的作用：目的1.确定B-Myb的异位表达对股动脉损伤所致病变形成的影响。为了阐明高脂肪饮食的影响，将B-MYB转基因小鼠与ApoE基因敲除小鼠杂交，以将B-Myb过度表达置于ApoE-/背景的背景中。将评估B-Myb表达对基质沉积、病变形成和血管壁几何重构的影响；目的2.阐明转录抑制的机制 目的3.阐明Cyclin A磷酸化抑制B-Myb抑制基质基因表达的机制；目的4.阐明CMV IE1蛋白激活NF-kappaB RelB亚单位的机制及其在调控细胞增殖的基因反式激活中的作用。这些研究将为心血管疾病中两个关键介质的控制提供重要的新信息：血管SMC增殖和基质产生。

Vascular smooth muscle cells (SMCs), the major cellular constituent of an artery, synthesize of the bulk of the connective tissue of the vessel wall, including elastin and the fibrillar collagens type I and V/XI. In response to injury and in certain disease states such as atherosclerosis, normally quiescent medial SMCs migrate to the intima where they undergo proliferation, and deposit matrix components, thereby contributing to formation of an atherosclerotic plaque and to vessel occlusion. Importantly, mounting evidence indicates that rupture of the fibrous cap of the plaque leads to thromboembolic complications in atherosclerotic coronary and carotid artery disease. Cytomegalovirus (CMV) infection has been implicated as a contributing agent in the pathogenesis of atherosclerosis, as well as in restenosis. Work in the PI's lab has led to the hypothesis that the myb and NF-kappaB families of transcription factors play key roles in coordinated control of matrix synthesis and proliferation of the vascular SMC. B-Myb was found to repress SMC type I and V collagen and elastin gene transcription in culture and phosphorylation by cyclin A/cdk2 relieved repression of the alpha2(V) collagen promoter. A transgenic mouse model carrying the B-myb transgene was recently created; the aortae and isolated SMCs of the transgenic mice were found to display a large decrease in elastin and substantially reduced collagen and lysyl oxidase mRNA expression compared to wild type mice. While B-myb gene expression is regulated by SMC growth state, c-Myb and A-Myb were shown to promote vascular SMC proliferation. Furthermore, the CMV immediate early (IE) 1 protein was found to selectively induce RelB/p50 NF-kappaB complexes, which may control transcription of genes that promote SMC proliferation. Here, four aims are proposed to elucidate the roles of Myb and NF-kappaB factors in cardiovascular disease: Aim 1. Determine the effects of ectopic expression of B-Myb on lesion formation as a result of femoral artery injury. To elucidate the effects of a high fat diet, the B-myb transgenic mice will be crossbred with an ApoE knockout mouse to place B-Myb overexpression within the context of an ApoE -/ background. The effects of B-Myb expression on matrix deposition, lesion formation, and geometric remodeling of the vessel wall will be evaluated; Aim 2. Elucidate the mechanism of transcriptional repression of elastin gene expression by B-Myb; Aim 3. Elucidate the mechanism whereby cyclin A phosphorylation ablates the ability of B-Myb to repress matrix gene expression; Aim 4. Elucidate the mechanism of NF-kappaB RelB subunit activation by CMV IE1 protein and its role in transactivation of genes that control cell proliferation. These studies should provide important new information on control of two critical mediators in cardiovascular disease: vascular SMC proliferation and matrix production.