Beta Andrenergic Receptor Structure and Desensitization

132-肾上腺素能受体(132AR)在“战或逃”反应中起主要作用 包括支气管扩张的调解。用激动剂引起的支气管扩张 132AR与用于治疗炎症的类固醇一起，是慢性哮喘的主要治疗方法。 已知支气管扩张剂的有效性随着时间的推移而降低(脱敏)， 因此，132AR激动剂脱敏的特征一直是 大量研究的焦点，从这些研究中得出的证据使其成为 G蛋白偶联受体的研究范式。然而，许多人 关于脱敏的分子机制仍然存在问题，以及 重要的是。132AR信号复合体是如何在去除 刺激。在系统生物学水平上，需要动态建模 132AR被PKA磷酸化的复杂抑制反馈环 G蛋白偶联受体激酶亚型及其下游后遗症 如arrestin与磷酸二酯酶的结合、内化和激活。自.以来 大多数对132AR脱敏的研究都是在细胞系中进行的 过度表达132AR，有必要研究初级脱敏 表达内源性132AR水平的人细胞。另一个方面是 脱敏抑制剂的研究进展很少受到关注。我们的 该小组在正在进行的132AR的三个领域的研究中取得了重大进展 脱敏过程；GRKs的GPCR激活的特征，发展 GRK活性抑制剂小组，以及脱敏和 再增敏，导致以下特定目的：(1)132AR的特性 HASM和模型细胞系统的脱敏作用，重点是定量 控制132AR功效和132AR效果损失的过程的系统建模 第二信使cAMP通过磷酸二酯酶的下游作用 (2)132AR活化GRKs机理的确定 受体和相关的GPCR视紫质通过详细的结构/功能研究 进化上重要的GRK残基；以及(3)多肽抑制剂的开发 这中断了基于获得的重要GRK知识的GPCRlGRK相互作用 参与相互作用的132AR结构域。

The 132-adrenergic receptor (132AR) plays a major role in the "fight-or-flight" response including mediation of bronchodilation. Eliciting bronchodilation with agonists of the 132AR is, along with steroids to treat inflammation, a major treatment of chronic asthma. The effectiveness of the bronchodilators is known to decrease over time (desensitize), and as such the characterization of agonist desensitization of the 132AR has been the focus of a multitude of studies, and the evidence derived from these has made it a paradigm for the study of G protein coupled receptors (GPCRs). However, many questions remain concerning the molecular mechanisms of desensitization, and importantly. how the 132AR signaling complex resensitizes following removal of stimulation. At the systems biology level, there is a need for a dynamic modeling of the complex inhibitory feedback loops involving 132AR phosphorylation by PKA and multiple G protein coupled receptor kinase (GRK) subtypes, and their downstream sequelae such as arrestin binding, internalization, and activation of phosphodiesterase. Since most studies of 132AR desensitization have been performed with cell lines overexpressing the 132AR, there is a need for studies of desensitization in primary human cells expressing endogenous levels of the 132AR. Another aspect that has received little attention has been the development of inhibitors of desensitization. Our group has made significant inroads in ongoing studies of three areas of the 132AR desensitization process; characterization of GPCR activation of GRKs, development of a panel of inhibitors of GRK activity, and systems modeling of desensitization and resensitization, leading to the following specific aims: (1) characterization of 132AR desensitization in both HASM and model cell systems with a focus on quantitative systems modeling of the processes that control loss of both 132AR efficacy and downstream actions of the second messenger cAMP through phosphodiesterase hydrolysis; (2) determination of the mechanism of activation of GRKs by the 132AR receptor and the related GPCR rhodopsin through detailed structure/function studies of evolutionarily important GRK residues; and (3) development of peptide inhibitors that disrupt the GPCRlGRK interaction based on knowledge gained of important GRK and 132AR domains involved in the interaction.