ATRAP IN VASCULAR GROWTH AND REMODELING

描述(申请人提供)：血管紧张素II(AT1)受体相关蛋白ATRAP是一种新的跨膜蛋白，被鉴定为AT1受体的选择性伙伴，但ATRAP对AT1受体功能的作用尚未阐明(S)。我们最近的体外研究表明，用RNAi敲除ATRAP导致Akt磷酸化降低，血管平滑肌细胞(VSMC)增殖减少，而通过体内基因转移过表达ATRAP导致心脏和血管肥大。综上所述，我们的数据表明ATRAP在血管生长中发挥着重要作用。我们的中心假设是ATRAP与AT1受体的生化相互作用在受体的信号活性中起着关键作用，并且在体内AT1受体介导的血管活动中具有重要的功能。因此，本研究将重点研究ATRAP介导的血管生长的机制，并通过以下目的来研究ATRAP在血管功能中的作用：目的1)确定ATRAP介导的细胞生长的分子机制。我们将研究ATRAP基因敲除下调Akt的机制及其对细胞生长和凋亡的影响；我们将表征Akt的磷酸化，并确定Akt、PI3-K和PDK1的直接调节因子的激活状态；目的2)在体内研究ATRAP表达不足对血管功能和重塑的影响。根据VSMCs的数据，我们推测ATRAP将是血管功能的决定因素，它的缺失将导致血管平滑肌细胞生长、血管收缩和血管重塑的迟钝。因此，我们将评估血管的收缩能力，我们将使用血管重塑的活体模型来评估血管壁对血管紧张素转换酶基因敲除小鼠或野生型小鼠的结构反应。我们还将描述ATRAP基因敲除对血管血流动力学的影响。这项拨款申请中描述的研究将为了解AT1受体与ATRAP相互作用的机制和功能意义提供关键信息，并将对开发新的心血管疾病治疗药物具有重要意义。

DESCRIPTION (provided by applicant): The Angiotensin II type I (AT1) receptor-associated protein, ATRAP, is a novel transmembrane protein identified as a selective partner of AT1 receptor, however the role of ATRAP on AT1 receptor function(s) has not been elucidated. Our recent in vitro studies showed that ATRAP knock down using RNAi resulted in a decrease in Akt phosphorylation and a reduction in vascular smooth muscle cell (VSMC) proliferation whereas overexpression of ATRAP by in vivo gene transfer resulted in cardiac and vascular hypertrophy. Taken together, our data suggest that ATRAP plays an important role in vascular growth. Our central hypothesis is that the biochemical interaction of ATRAP with AT1 receptor plays a critical role in the signaling activity of the receptor and is functionally important for AT1 receptor-mediated vascular actions in vivo. Accordingly, this application will focus on the mechanism of ATRAP mediated vascular growth and will examine the role of ATRAP in vascular function by the following aims: Aim 1) To identify the molecular mechanism of ATRAP-mediated cell growth. We will examine the mechanisms of Akt downregulation by ATRAP knockdown, and its consequences on cell growth and apoptosis; we will characterize the phosphorylation of Akt and we will determine the state of activation of the immediate regulators of Akt, PI3-K and PDK1; Aim 2) To study in vivo the consequences of deficiency in ATRAP expression on vascular function and remodeling. Based on the data in VSMCs we postulate that ATRAP will be determinant in vascular function and its loss would result in a blunting of smooth muscle cell growth, vascular contractility and vascular remodeling. Therefore, we will evaluate vessel contractility and we will use an in vivo model of vascular remodeling to assess the structural response in the vessel wall to Ang II infusion into ATRAP knockout or wild type mice. We will also characterize the consequences of ATRAP knockout on vascular hemodynamics. The studies described in this grant application will provide critical information to understand the mechanism and functional significance of AT1 receptor interaction with ATRAP and will have important implications for the development of novel therapeutic agents for cardiovascular diseases.