Molecular Regulation of Cardiovascular 7 TM Receptors

 描述(申请人提供)：心血管功能的所有方面都由七个跨膜受体(7TMR或GPCR)家族的受体调节，它们是治疗药物最常见的靶点。调节这些受体的一个普遍机制是异源三聚体G蛋白信号的脱敏。传统上，这是通过两个步骤进行调解的 激活的受体被G蛋白偶联受体激酶磷酸化的过程，导致G蛋白进一步激活的空间位阻分子的结合。最近，情况变得很清楚，它还可以充当多功能适配器，它们本身就可以充当信号传感器。此外，可以找到许多受体配体，它们不成比例地激活G蛋白或B arr介导的信号转导。 “有偏向的配体”，可能具有更强的作用专一性和更少的副作用。血管紧张素II 1型受体(AT1R)的一个这样的配体现在正在进行失代偿性充血性心力衰竭的临床试验。因此，这项提议有三个紧密联系的目标，涉及发展分子和原子水平的理解，以两个对心血管具有重大意义的受体--2-肾上腺素能受体和AT1R-受体为模型系统，研究这种由ARR介导的信号是如何产生的。1)利用一组值得注意的G-和？arr-倾向性AT1R多肽配体来确定AT1R偏向激动性的分子机制，我们之前已经对其进行了表征。我们将利用动态生物物理技术，如电子顺磁共振和氢-氚交换质谱仪，来揭示偏向受体构象的本质。2)通过将这些相同的技术应用于这两个受体与？arr的复合体，获得关于受体和？arr构象的信息，以确定7TMR-？arr相互作用的分子机制。3)结晶并确定了7TMR-？ARR络合物的结构。我们将产生的见解有可能指导强大的新心血管药物的设计，并将进一步加深我们对7TMR家族保守的信号机制的理解。

 DESCRIPTION (provided by applicant): All aspects of cardiovascular function are regulated by receptors of the seven transmembrane receptor (7TMR or GPCR) families, and they are the commonest target of therapeutic drugs. A universal mechanism regulating these receptors is desensitization of heterotrimeric G protein signaling. Classically, this is mediated by a two- step process in which activated receptors are phosphorylated by G protein-coupled receptor kinases, leading to the binding of a ß-arrestin (ßarr) molecule which sterically interdicts further activaion of the G protein. More recently it has become clear that ßarrs can also serve as multifunctional adaptors which act as signal transducers in their own right. Moreover, many receptors ligands can be found which disproportionately activate either G protein- or ßarr-mediated signaling - i.e. "biased ligands" which may possess greater specificity of action and fewer side effects. One such ligand for the angiotensin II type 1 receptor (AT1R) is now in clinical trials for decompensated congestive heart failure. Accordingly this proposal has three closely linked aims which involve developing a molecular- and atomic-level understanding of how such ßarr-mediated signaling is generated using as model systems two receptors of great cardiovascular significance, the ß2- adrenergic receptor and the AT1R. 1) To determine the molecular mechanisms underlying biased agonism at the AT1R utilizing a remarkable panel of both G- and ßarr-biased AT1R peptide ligands which we have previously characterized. The dynamic biophysical techniques of electron paramagnetic resonance and hydrogen deuterium exchange mass spectrometry will be utilized to reveal the nature of the biased receptor conformations. 2) To determine the molecular mechanisms underlying 7TMR-ßarr interactions by applying these same techniques to complexes of these two receptors with ßarr, obtaining information on both receptor and ßarr conformations. 3) To crystallize and determine the structures of these 7TMR-ßarr complexes. The insights which we will generate have the potential to guide the design of powerful new cardiovascular drugs and will further our understanding of the conserved signaling mechanisms of the greater 7TMR family.