B-MYB REGULATION OF MATRIX GENE EXPRESSION

血管平滑肌细胞(SMCs)合成大部分基质 主要动脉中层中的蛋白质，并负责 阻塞血管内血流的基质蛋白的沉积 动脉粥样硬化斑块中的内膜。我们最近证明了B- MYB是MYB转录因子家族的成员，其表达方式为 SMC呈细胞周期依赖方式，而B-MYB呈负相关 调节编码两种I型胶原基因的启动子活性 链和α2链和赖氨酰氧化酶(LO)启动子，在 分别与J.Foster和H.Kagan合作。自B-MYB以来 在增殖活跃的SMC中高表达，随着细胞的增多而降低 生长缓慢，B-MYB对基质基因表达的负面调节可能 代表先前反向关系的一个重要组成部分 观察基质生成与血管平滑肌细胞生长之间的关系。四 提出了具体的目标，以提供B-MYB的附加特征 并开始阐明B-myb下调的机制。 调节基质的表达并评价这种负性的作用 体内基质基因表达的效应因子。目标1：描述 碱性成纤维细胞密度对B-MYB表达的影响 成纤维细胞生长因子或cAMP水平的调节。目标2： 定位启动子和可能的内含子序列，介导B-myb的下调- I型胶原、弹性蛋白和LO基因转录的调控。目标3： B-MYB下调基质基因表达机制的研究 以α2(V)胶原基因为范式进行转录。目标4： 确定B-MYB在血管壁表达的功能作用 转基因小鼠模型。这些研究应该会揭示 B-myb的表达及其转录因子在调控中的作用 基质的产生和正常管壁的形成。最后， 这些发现应该为血管疾病提供有价值的见解。 涉及SMC的过量基质沉积和增殖，包括 动脉粥样硬化和血管再通。

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.