Angiotensin II Receptor Signaling Domains

描述：(逐字摘自申请)：肾素-血管紧张素系统是 在正常生理和高血压和疾病中的重要作用 动脉硬化。血管紧张素II(Ang II)与血管紧张素转换酶等相互作用 血管平滑肌细胞II型1A型受体(AT、AR) 几种磷脂酶(PL)的激活。第二阶段或主要阶段 信号需要AT14R的内吞作用或将其隔离到未定义的 离散信令领域，这是该提案的一个主要焦点。此外，Ang II 增加细胞内钙离子，激活蛋白激酶C、Src家族 激酶和JAK激酶，以及丝裂原激活的蛋白激酶， 介导VSMC肥大和生长。重要的是，镁II诱导健壮 产生的活性氧物种(ROS)是信号的主要修饰物 一代。依赖钙离子的表皮生长因子反式激活 受体(EGF-R)是组装信号复合体的“支架” 包括CSRC、PYK2和下游适配器(Shc、Grb2、SOS)，导致 ERK1/2和蛋白激酶B/Akt的激活。人们对此知之甚少 VSMC膜AT、A-R信号的时空组织及其机制 实现了专一性。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 专门化领域。功能截然不同的微域，具有 脂类成分，即“脂筏”，已在质膜中被鉴定。 “木筏”定位信号分子，包括受体、G蛋白亚基、 适配器分子，以及一系列信号产生蛋白。它们的作用是 促进通路和信号蛋白之间相互作用的支架。 小凹是包含主要结构的细胞膜内陷。 蛋白质小窝和木筏的特殊形式。我们已经证明了Ang II 刺激VSMC导致AT、A-R进入富含小窝的运动 膜组分。它最初的基本位置还没有确定。另一大专业 信号结构域是含有整合素的焦点黏附或复合体 受体和许多相关的信号分子以及小窝蛋白。EGF R与小窝和灶性粘连有关。我们的预赛 有数据表明，镁诱导的EGF-R和某些 下游通路依赖于ROS，提示两者都参与其中 小窝蛋白和焦点黏附相关分子。我们假设 血管紧张素转换酶11诱导的VSMC信号谱系取决于几个主要的 “脚手架”和离散的信号域。要深入了解这些问题 我们提出了三个具体目标：1)基本定位和机制 AT1ARS转移到小窝富集组分；2)测定 这种转移或封存的功能后果；以及3)确定 ROS在影响相关信号通路中的作用。获得洞察力 在对Ang II信号转导机制的了解中将导致 对高血压的发病机制和潜在治疗的认识 动脉硬化。

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.