Structure-Guided Analysis of Mechanisms of AT1R Functions

 描述(申请人提供)：众所周知，血管紧张素转换酶1型受体(AT1R)是正常心血管生理的主要调节因子。在多种疾病中，AT1R的慢性刺激可通过血管紧张素转换酶诱导的细胞异常生长、黏附、迁移和炎症基因表达而导致器官损伤。AT1R受体阻滞剂(ARB)能有效控制高血压，但由于机制不明，其预防器官损伤的效果差异很大。已有多个实验室致力于阐明AT1R信号转导过程的分子基础。我们的研究主要集中在AT1R的结构、构象和药理机制等方面。我们是第一个在AT1R中显示配体非依赖和有偏信号的人，这导致了AT1R功能子集的配体调节的概念。我们最近首次阐明了ARB结合的人类AT1R的3D结构，这是开始对这种降压药物靶点进行基于结构的研究的重要一步。利用这一新知识，我们将解决尚未解决的问题，包括：(I)针对AT1R的临床药物的功能疗效是如何由受体内不同的配体亚袋决定的？(Ii)AT1R中嵌入的假定的细丝素-A结合基序如何调节细胞骨架动力学和细胞黏附特性？(Iii)AT1R功能的激活和调节的哪个方面会因AT1R中自然发生的结构变化而改变？我们的初步研究提供了以下方面的见解：(I)AT1R-配体亚袋影响ARB的不同疗效；(Ii)血管紧张素Ⅱ诱导AT1R与细丝素的结合，这可能是导致黏附依赖细胞功能的新途径；以及(Iii)自然存在于人群中的人类AT1R变体可能的结构效应。我们这一应用的具体目标是：(目标1)验证如下假设，即在临床实践中，结构上不同的ARB的疗效取决于AT1R 3D结构中的不同配位子口袋。(目的2)验证Angii诱导的AT1R与细丝素的相互作用受一种新的蛋白质-蛋白质相互作用机制调节的假设。(目的3)检验在人类群体研究中报道的AT1R变体改变功能结构域之间耦合的假设。我们将在临床前研究中使用最先进的分子、生物物理、细胞生物学和体内技术，以促进我们对AT1R生物学中长期悬而未决的问题的理解。我们的发现很容易转化到临床上，并可能促进新疗法的开发。

 DESCRIPTION (provided by applicant): The AngII type 1 receptor (AT1R) is widely known to be the master regulator of normal cardiovascular physiology. In a variety of diseases chronic stimulation of AT1R causes organ damage due to AngII-induced abnormal growth, adhesion, migration and inflammatory gene expression in cells. AT1R blockers (ARBs) effectively control hypertension but their efficacy in preventing organ damage varies widely due to unknown mechanism. Efforts have been made in several laboratories to elucidate the molecular basis of pleotropic AT1R signaling process. We have focused our research on structure, conformation and pharmacological mechanisms governing AT1R. We were the first to show ligand-independent and biased signaling in AT1R, leading to the concept of ligand modulation of subset of AT1R functions. We have recently elucidated first 3D-structure of an ARB-bound human AT1R, as an important step for beginning structure-based studies of this antihypertensive drug-target. With this new knowledge, we will address unresolved questions including: (i) how functional efficacy of clinically used drugs targeting AT1R is determined by different ligand sub-pockets within the receptor? (ii) How does a putative filamin-A binding motif embedded in AT1R operates in regulating cytoskeletal dynamics and cell adhesion properties? (iii) What aspect of activation and regulation of AT1R functions is altered by naturally occurring structural variations in AT1R? Our preliminary studies provide insight regarding (i) AT1R-ligand sub-pockets influencing differential efficacies of ARBs; (ii) AngII-induced engagement of filamin by AT1R which may be a novel pathway leading to adhesion- dependent cell functions; and (iii) possible structural effects of human AT1R variants naturally occurring in population. Our specific goals for this application are: (Aim 1) to test the hypothesis that efficacy of structuraly different ARBs in clinical practice is determined by different ligand sub-pockets found in the AT1R 3D-structure. (Aim 2) to test the hypothesis that AngII-induced AT1R interaction with filamin is regulated by a novel protein- protein interaction mechanism. (Aim 3) to test the hypothesis that AT1R variants reported in human population studies alter coupling between functional domains. We will use state-of-the-art molecular, biophysical, cell biology and in vivo techniques in our preclinical studies to advance our understanding of long unresolved issues in AT1R biology. Our findings are easily translatable to the clinic and may facilitate the development of novel therapeutics.