HCMV US28 Signal Transduction by Betaarrestin proteins

描述（由申请人提供）：人类巨细胞病毒（HCMV）感染是病毒相关先天性出生缺陷的主要原因，已被证明是器官移植受者和艾滋病患者的重大公共卫生问题。越来越多的证据表明，HCMV可能与血管疾病的发生有关。HCMV和免疫系统之间的相互作用是导致疾病发生的关键因素。有趣的是，HCMV编码了几个似乎可以调节免疫系统功能的基因。其中一个被称为US28的基因与哺乳动物趋化因子g蛋白偶联受体（gpcr）同源。虽然最近在US28下游信号通路的鉴定方面取得了进展，但对于US28附近促进信号通路激活的分子细节知之甚少。本提案的目的是确定US28附近的特定受体特性和分子事件，这些特性和事件对已知信号转导途径的激活至关重要。我们假设对β捕捕素蛋白与US28分子相互作用的详细研究将对US28信号的调控产生新的见解。β -拘捕素最初是在终止“传统”g蛋白信号传导效应物（如腺苷酸环化酶和磷脂酶）的背景下发现的。这种终止过程，也被称为脱敏，涉及grk的受体磷酸化和β抑制素蛋白的结合。现在很清楚，β -拘捕素同时作为适配器/支架分子，将信号蛋白招募到受体，以激活额外的“非传统”信号通路。我们已经确定了一个US28突变体，它不能与β捕捕素相互作用，并产生了大量关于该突变体信号传导的初步数据。我们建议分析β捕捕素蛋白在US28信号通路中的参与，以便更好地了解导致US28信号通路激活的近端事件。为实现这一目标，我们提出三个具体目标。首先，我们将在HCMV感染的背景下描述US28突变体的“传统”信号，并分析该突变体如何影响US28刺激平滑肌细胞迁移的能力。其次，我们将分析可能由β捕捕素募集介导的US28到US28羧基末端调控域的“非传统”信号通路。第三，我们将分析缺乏β捕虏素表达的细胞中的US28信号，以明确β捕虏素的参与。

DESCRIPTION (provided by applicant): Human Cytomegalovirus (HCMV) infection is a leading cause of viral associated congenital birth defects and has proven to be a significant public health problem in organ transplant recipients as well as in individuals with AIDS. Accumulating evidence indicates that there may be a relationship between HCMV and the development of vascular disease. The interplay between HCMV and the immune system is a critical factor in the events leading to initiation of disease. Interestingly, HCMV encodes several genes that appear to modulate immune system function. One of these genes, termed US28, is homologous to the mammalian chemokine G-protein coupled receptors (GPCRs). While progress has recently been made in the identification of signaling pathways downstream of US28, very little is known regarding the molecular details proximal to US28 that contribute to the activation of signaling pathways. The objective of this proposal is to identify specific receptor properties and molecular events proximal to US28 that are critical for activation of known signal transduction pathways. We hypothesize that a detailed study of the molecular interactions of betaarrestin proteins with US28 will generate novel insights into the regulation of US28 signaling. The betaarrestins were originally identified in the context of termination of "traditional" G-protein signaling to effectors such as adenylyl cyclases and phospholipases. This termination process, also known as desensitization, involves receptor phosphorylation by GRKs and binding of betarrestin proteins. It is now clear that the betaarrestins simultaneously function as adapter/scaffold molecules to recruit signaling proteins to receptors in order to activate additional "non-traditional" signaling pathways. We have identified a US28 mutant that is unable to interact with betaarrestin and have generated a significant amount of preliminary data regarding signaling from this mutant. We propose to analyze the involvement of betaarrestin proteins in US28 signaling in order to gain a greater understanding of the proximal events leading to activation of US28 signaling pathways. To accomplish this goal, we propose three specific aims. First, we will characterize "traditional" signaling from this US28 mutant in the context of HCMV infection and will analyze how this mutant affects the ability of US28 to stimulate smooth muscle cell migration. Second, we will analyze "non-traditional" signaling pathways from US28 potentially mediated by betaarrestin recruitment to the US28 carboxy terminal regulatory domain. Third, we will analyze US28 signaling in cells deficient for betaarrestin expression in order to specifically define the involvement of betaarrestins. Our preliminary data indicate that US28 engages ?arrestin proteins suggesting that we will be able to make rapid progress toward our goal of defining the role of these important regulatory proteins in US28 signaling. These studies will identify mechanisms regulating US28 mediated signal transduction and will enhance our understanding of how US28 participates in pathogenesis and initiation of HCMV disease.