Mechanism of activation of natriuretic peptide receptors

描述（由申请人提供）：心房利钠肽（ANP）受体和同源的c型利钠肽受体是同源的，但启动不同的生理过程。ANP受体参与肾脏和心脏功能；它的激活导致肾内尿钠和利尿的增加和血压的降低。ANP受体激活肽BNP对充血性心力衰竭患者有临床益处。c型利钠肽受体最近被我们确定为导致骨骼生长受损的人类突变的目标。这两种受体都属于膜结合的鸟苷环化酶家族，包含细胞外配体结合域、跨膜螺旋结构域、激酶同源结构域、螺旋状结构域和鸟苷环化酶结构域。细胞外激素与这些受体结合导致细胞内第二信使cGMP的产生。我们之前已经确定了ANP受体胞外配体结合域的2.0埃分辨率晶体结构。提出的研究是我们多学科努力研究这些受体激活机制的延续。我们的第一个特定目的是研究激酶同源结构域的一个作用是否作为激活机制的一部分保持细胞外结构域的分离。这将使用细胞内结构域和全长ANP受体的结构生物学方法进行测试。第二个目的是测试ANP受体的结构域是正确定位的假设，并优化了长度。这将通过针对域间区域的插入和删除突变研究来探讨。第三个特定目的是确定在激活机制中跨膜螺旋是否参与膜内的横向运动。第四个目的是验证c型利钠肽受体的一些遗传缺陷涉及影响这些受体信号转导机制的突变的假设。这些关于利钠肽受体的研究将增加我们对其激活和功能机制的理解，并可能促进新的肾脏、心血管或骨骼生长刺激药物的开发。

DESCRIPTION (provided by applicant): The atrial natriuretic peptide (ANP) receptor and the homologous c-type natriuretic peptide receptor are homologous yet initiate distinct physiological processes. The ANP receptor is involved in renal and cardiac functions; its activation leads to an increase in natriuresis and diuresis in the kidney and decreased blood pressure. The ANP receptor activating peptide BNP has clinical benefits for congestive heart failure patients. The C-type natriuretic peptide receptor has recently been identified by us as the target for human mutations that cause impaired skeletal growth. Both receptors belong to the family of membrane bound guanylyl cyclases and contain an extracellular ligand binding domain, a transmembrane helix, a kinase-homology domain, a coiled-coil, and guanylyl cyclase domain. Extracellular hormone binding to these receptors leads to the intracellular production of the second messenger cGMP. We have previously determined the 2.0 Angstrom resolution crystal structure of the extracellular ligand binding domain of the ANP receptor. The proposed studies are a continuation of our multi-disciplinary efforts to investigate the mechanism of activation of these receptors. Our first Specific Aim is to investigate whether 1 of the roles of the kinase homology domain is to keep the extracellular domains apart as part of the activation mechanism. This will be tested using structural biology methods with both the intracellular domains as well as with the full length ANP receptor. The second Aim is to test the hypothesis that the domains of the ANP receptor are correctly positioned, and optimized for length. This will be probed by insertional and deletion mutagenesis studies targeting the inter-domain regions. The third Specific Aim is to determine whether the transmembrane helices are involved in lateral movements within the membrane during the activation mechanism. The fourth Aim is to test the hypothesis that a number of the genetic defects in the c-type natriuretic peptide receptor involve mutations that affect the signal transduction mechanism of these receptors. These proposed studies on natriuretic peptide receptors will increase our understanding of mechanisms of activation and function, and could enhance the development of new renal, cardiovascular, or skeletal growth stimulatory drugs.