Integrin Signaling In Vascular Cells

描述（申请人提供）：血管平滑肌细胞（SMC）生长和迁移异常导致高血压、动脉粥样硬化和再狭窄。SMC功能受复杂的调控机制控制，部分受与细胞外基质的相互作用控制。整合素是细胞外基质的主要受体，激活粘附依赖的信号通路，并与生长因子和g蛋白偶联受体相互作用，影响细胞功能。本应用程序的目的是了解整合素α - vbeta3依赖性信号传导如何影响SMC生长和迁移。我们观察到，用β 3-整合素抗体抑制剂治疗的野生型小鼠，而不是β 3-整合素缺陷（β 3-/-）小鼠，可以防止内膜增生的发生，并且发现培养的野生型和β 3-/- SMCs的特性存在差异，这可能解释了我们在体内的观察结果。基于我们的初步数据，我们假设在刺激和静止的SMCs中，整合素依赖性的细胞内信号通过不同的途径正向和负向调节SMC的生长和迁移。拟议的研究将利用遗传学、药理学和RNA干扰技术，在具有良好特征的细胞和动物SMC功能模型中靶向整合素alphaVbeta3。首先，我们将确定受刺激的SMCs中依赖alphavbeta3的通路。我们的初步数据表明，alphaVbeta3作为分子开关调节Rho家族GTPase并控制焦点粘附组装。我们将描述负责调控GTPase的机制。其次，根据我们的初步数据，我们已经确定了alphaVbeta3在细胞静止期间下调p38MAPK的作用。我们将使用p38 MAPK通路作为模型来了解依赖alphavbeta3的通路如何促进SMC静止。第三，我们将描述alphaVbeta3在培养血管和完善的小鼠动脉损伤模型中的生理反应。这些结果将为了解SMC alphaVbeta3在再狭窄和动脉粥样硬化中的功能提供具体的见解，并可能对了解alphaVbeta3整合素在血管生成、骨质疏松和其他疾病中的功能具有广泛的意义。

DESCRIPTION (provided by applicant): Abnormal vascular smooth muscle cell (SMC) growth and migration contributes to hypertension, atherosclerosis, and restenosis. SMC function is controlled by complex regulatory mechanisms, which are governed in part by interactions with the extracellular matrix. Integrins, the predominant receptors for the extracellular matrix, activate adhesion-dependent signaling pathways and cross-talk with growth factor and G-protein coupled receptors to influence cellular functions. The objective of this application is to understand how integrin alphaVbeta3-dependent signaling influences SMC growth and migration. We observed that wild-type mice treated with an antibody-inhibitor of beta3-integrins, but not beta3-integrin-deficient (beta3-/-) mice, were protected from the development of intimal hyperplasia and have found differences in the properties of cultured wild-type and beta3-/- SMCs that may account for our in vivo observations. Based on our preliminary data, we hypothesize that integrin alphaVbeta3- dependent intracellular signaling positively and negatively regulates SMC growth and migration thorough distinct pathways in stimulated and quiescent SMCs. The proposed studies will utilize genetic, pharmacologic, and RNA interference techniques to target integrin alphaVbeta3 in well-characterized cellular and animal models of SMC function. First, we will identify alphaVbeta3-dependent pathways in stimulated SMCs. Our preliminary data indicates that alphaVbeta3 serves as a molecular switch to regulate Rho Family GTPase and control focal adhesion assembly. We will delineate the mechanism(s) responsible for GTPase regulation. Second, based on our preliminary data, we have identified a role for alphaVbeta3 in downregulation of p38MAPK during cellular quiescence. We will use the p38 MAPK pathway as a model to understand how alphaVbeta3-dependent pathways contribute to SMC quiescence. Third, we will delineate the contribution of alphaVbeta3 to physiologic responses in cultured vessels and well-established mouse models of arterial injury. These results will provide specific insights into the function of SMC alphaVbeta3 in restenosis and atherosclerosis and may have broad implications for understanding alphaVbeta3 integrin function in angiogenesis, osteoporosis, and other disorders.