B-MYB REGULATION OF MATRIX GENE EXPRESSION

血管平滑肌细胞（SMC）合成大部分基质 主要动脉中层内的蛋白质， 基质蛋白的沉积阻塞了血管内的血流， 动脉粥样硬化斑块中的内膜。我们最近证明了B- myb是转录因子myb家族的一员， SMC呈细胞周期依赖性，B-myb呈阴性 调节编码两种I型胶原的基因的启动子活性 链以及α 2链和赖氨酰氧化酶（LO）启动子， 与J. Foster和H.卡根，分别。自从B-myb 在增殖活跃的SMC中表达较高，随着细胞增殖的增加， 生长减慢，B-myb对基质基因表达的负调节可能 表示先前的反向关系的重要组成部分 基质生产和血管平滑肌细胞的生长之间观察。四 提出了具体的目标，以提供额外的表征B-myb 表达，并开始阐明B-myb下调的机制。 调节基质表达，并评估这种负作用 影响体内基质基因表达。目标1：表征 碱性磷酸酶处理SMC细胞密度对B-myb表达的影响 成纤维细胞生长因子（bFGF）或调节cAMP水平。目标二： 定位启动子和可能的内含子序列介导B-myb下调， I型胶原、弹性蛋白和LO基因转录的调节。目标3： 阐明B-myb下调基质基因的机制 使用α 2（V）胶原基因作为范例进行转录。目标4： 用免疫组织化学方法确定B-myb在血管壁中表达的功能作用， 转基因小鼠模型。这些研究应该阐明 B-myb的表达及其在调控中的作用 基质的产生和正常血管壁的形成。最后， 这些发现将为血管疾病提供有价值的见解 涉及SMC的过度基质沉积和增殖，包括 动脉粥样硬化和再狭窄。

Vascular smooth muscle cells (SMCs) synthesize the bulk of the matrix proteins within the medial layer of major arteries and are responsible for the deposition of matrix proteins that occlude blood flow within the intima in an atherosclerotic plaque. We have recently demonstrated that B- myb, a member of the myb family of transcription factors, is expressed by the SMC in a cell cycle dependent fashion, and that B-myb negatively regulates promoter activity of the genes encoding the two type I collagen chains and the alpha2 chain and lysyl oxidase (LO) promoters, in collaboration with J. Foster and H. Kagan, respectively. Since B-myb expression was high in actively proliferating SMCs, and decreased as cell growth slowed, negative regulation of matrix gene expression by B-myb may represent an important component of the inverse relationship previously observed between matrix production and growth of vascular SMCs. Four specific aims are proposed to provide additional characterization of B-myb expression in SMCs and to begin to elucidate the mechanism of B-myb down- regulation of matrix expression and to evaluate the role of this negative effector on in vivo matrix gene expression. Aim 1: characterize the effects on B-myb expression of cell density treatment of SMCs with basic fibroblast growth factor (bFGF) or modulation of cAMP levels. Aim 2: localize promotor and possible intronic sequences mediating B-myb down- regulation of type I collagen, elastin and LO gene transcription. Aim 3: elucidate the mechanism of B-myb down-regulation of matrix gene transcription using the alpha2(V) collagen gene as paradigm. Aim 4: determine the functional role of B-myb expression in the vessel wall using a transgenic mouse model. These studies should shed light on the expression of B-myb and the role of this transcription factor in control of matrix production and formation of the normal vessel wall. Lastly, these findings should provide valuable insights into vascular disease involving excess matrix deposition and proliferation by the SMC, including atherosclerosis and restonosis.