Molecular Regulation of Cardiovascular 7 TM Receptors

 描述（由申请人提供）：心血管功能的所有方面均由七跨膜受体（7 TMR或GPCR）家族的受体调节，并且它们是治疗药物最常见的靶标。调节这些受体的普遍机制是异源三聚体G蛋白信号转导的脱敏。传统上，这是通过两步 活化受体被G蛋白偶联受体激酶磷酸化的过程，导致β-抑制蛋白（β-arrestin，β-R）分子的结合，后者在空间上阻止G蛋白的进一步活化。最近，人们清楚地看到，ßarrs还可以作为多功能适配器，其本身就充当信号转换器。此外，可以发现许多受体配体不成比例地激活G蛋白或β arr介导的信号传导，即 “偏向配体”可能具有更大的作用特异性和更少的副作用。一种这样的血管紧张素II 1型受体（AT 1 R）配体目前正在进行失代偿性充血性心力衰竭的临床试验。因此，该提议具有三个紧密相关的目标，其涉及使用具有重要心血管意义的两种受体（β 2-肾上腺素能受体和AT 1 R）作为模型系统，发展对如何产生这种β arr介导的信号传导的分子和原子水平的理解。1)为了确定在AT 1 R的偏激动作用的分子机制，利用我们先前表征的一组显著的G-和β arr-偏AT 1 R肽配体。动态生物物理技术的电子顺磁共振和氢氘交换质谱将被用来揭示的性质的偏见受体构象。2)通过将这些相同的技术应用于这两种受体与β受体的复合物，获得关于受体和β受体构象的信息，确定7 TMR-β受体相互作用的分子机制。3)结晶并确定这些7-TMR-β-内酰胺配合物的结构。我们将产生的见解有可能指导设计强大的新型心血管药物，并将进一步了解更大的7 TMR家族的保守信号传导机制。

 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.