Angiotensin II Receptor Signaling Domains

描述：（来自申请的逐字记录）：肾素-血管紧张素系统是 在正常生理和高血压疾病中很重要， 动脉粥样硬化血管紧张素II（Ang II）与血管紧张素受体相互作用。 血管平滑肌细胞（VSMCs）的II型1A受体（AT，AR），导致 几种磷脂酶（PL）的激活。第二阶段或主音阶段 信号传导需要AT 1 4 R的内吞作用或螯合作用， 离散信令域，这一建议的主要重点。此外，Ang II 增加细胞内钙，激活蛋白激酶C，Src家族 激酶和Jak激酶，以及促分裂原活化蛋白激酶， 介导VSMC肥大和生长。重要的是，Mg II诱导稳健的 产生活性氧物质（ROS），其是信号的主要调节剂 一代表皮生长因子的钙依赖性反式激活 受体（EGF R）作为信号复合物组装的“支架” 包括cSrc、Pyk 2和下游衔接子（Shc、Grb 2、Sos），导致 ERK 1/2和蛋白激酶B/Akt激活。关于这一点，我们知之甚少。 血管平滑肌细胞膜AT、AR信号的时空组织及其机制 实现了特异性。有证据表明，受体和相关的 信号分子不是随机分布的，而是定位在 专业领域。具有特征的功能不同的微区 在质膜中已经鉴定出脂质组成“脂筏”。 “筏”定位信号分子，包括受体，G蛋白亚基， 衔接分子和大量的信号产生蛋白质。他们作为 支架以促进通路和信号蛋白之间的相互作用。 小窝是细胞膜内陷，包含主要的结构 蛋白质小窝蛋白和特殊形式的筏。我们已经证明，Ang II 刺激VSMCs引起AT、A R运动到富含小窝的细胞中， 膜组分其原始的基底位置是不确定的。另一个主要 信号传导域是粘着斑或复合物，其包含整合素 受体和许多相关的信号分子以及小窝蛋白。的EGF R与小窝和局灶性粘连有关。我们的初步 数据表明，MgII诱导的EGF-R和某些 下游途径依赖于ROS，并表明两者都参与 小窝蛋白和粘着斑相关分子。我们假设， 血管紧张素11诱导的VSMC信号库依赖于几个主要的 “支架”和离散的信号传导结构域。为了深入了解这些问题 我们提出了三个具体的目标，包括：1）基础位置和机制 AT 1ARS向富含小窝的组分移动; 2）测定 这种移动或隔离的功能后果;以及3）确定 ROS在影响相关信号通路中的作用。获得的见解 了解血管紧张素II信号传导机制将导致增加 了解高血压的发病机制和潜在治疗方法， 动脉粥样硬化

DESCRIPTION: (Verbatim from the application): The renin-angiotensin system is important in normal physiology and the diseases hypertension and atherosclerosis. Angiotensin II (Ang II), interacts with, among others, the Ang II type 1A receptor (AT, AR) of vascular smooth muscle cells (VSMCs), leading to activation of several phospholipases (PL). The second or tonic phase of signaling requires endocytosis or sequestration of the AT1 4R to an undefined discrete signaling domain, a major focus of this proposal. Additionally, Ang II increases intracellular calcium, and activates protein kinase C, Src family kinases and Jak kinases, as well as mitogen activated protein kinases that mediate VSMC hypertrophy and growth. Importantly, Mg II induces robust generation of reactive oxygen species (ROS) that are major modifiers of signal generation. Calcium-dependent transactivation of the epidermal growth factor receptor (EGF R) serves as a "scaffold" for the assembly of a signaling complex including cSrc, Pyk2, and downstream adaptors (Shc, Grb2, Sos), leading to ERK1/2 and protein kinase B/Akt activation. Little is known of the spatial-temporal organization of AT,A R signaling in the VSMC membrane and how specificity is achieved. Evidence suggests that receptors and associated signaling molecules are not randomly distributed but are localized in specialized domains. Functionally distinct microdomains with characteristic lipid composition, "lipid rafts," have been identified in plasma membranes. "Rafts" localize signaling molecules including receptors, G-protein subunits, adaptor molecules, and a host of signal generating proteins. They serve as scaffolds to facilitate interactions among pathways and signaling proteins. Caveolae are cell membrane invaginations that contain the major structural protein caveolin and are specialized forms of rafts. We have shown that Ang II stimulation of VSMCs causes movement of the AT, A R into caveolae-enriched membrane fractions. Its original, basal location is undefined. Another major signaling domain is the focal adhesion or complex, which contains integrin receptors and many associated signaling molecules as well as caveolin. The EGF R has been associated with both caveolae and focal adhesions. Our preliminary data indicate that the Mg Il-induced transmodulation of the EGF-R and certain downstream pathways are dependent upon ROS and suggest involvement of both caveolin and focal adhesion associated molecules. We hypothesize that the full repertoire of Ang 11-induced signals in VSMC is dependent upon several major "scaffolds" and discrete signaling domains. To gain insight into these issues we propose three Specific Aims involving: 1) the basal location and mechanisms by which AT1ARS move to caveolae-enriched fractions; 2) determination of the functional consequences of this movement or sequestration; and 3) determination of the role of ROS in affecting the related signaling pathways. Insights gained in understanding of the mechanisms of Ang II signaling will lead to increased understanding of the pathogenesis and potential treatment of hypertension and atherosclerosis.