Segmented expression of a human cytomegalovirus-encoded heptaspanning protein

描述（由申请人提供）：人巨细胞病毒（HCMV）是一种重要的人类病原体，在免疫功能低下的个体和先天性感染的儿童中引起严重疾病。需要改进预防和控制HCMV感染的方法。开发新型抗病毒药物的一条途径是从鉴定和利用病毒与细胞生物学之间的新交叉点开始的。这方面的一个例子是HCMV编码几个七跨膜（7TM）蛋白，这些蛋白具有序列特性，使人联想到七聚氰胺信号分子，如G蛋白偶联受体。其中，pUS17（由US17基因编码）以分段方式表达，其n端结构域定位于细胞质病毒粒子装配室外围的细胞质，c端结构域定位于装配室中心和被感染的细胞核。我们假设pUS17片段是受调控的膜内蛋白水解（RIP）的产物，并且n端和c端pUS17片段在感染过程中具有生物学作用。RIP是一种重要的细胞调控机制，很少有病毒先例，其细胞机制尚未完全了解。因此，这代表了一个及时的机会，利用一个进化良好的病毒系统来研究具有普遍重要性的细胞机制，并确定这一过程在感染中的作用，以便这些信息可以用于设计新的抗病毒策略。因此，我们将确定和描述US17被分割的机制。这将包括(i)确定片段的边界（目标1），以及（ii）确定片段的生物发生是由于蛋白质水解、翻译还是转录过程（目标2）。这项工作的意义在于我们发现了一种新的病毒编码的7TM蛋白的细胞内调控模式，这种模式可能在细胞内通讯中发挥重要作用。如果有蛋白水解的需求，这将打开抗病毒开发工作的一个全新领域。这项工作将为理解HCMV生物学及其致病机制开辟重要的新途径。

DESCRIPTION (provided by applicant): Human cytomegalovirus (HCMV) is an important human pathogen, causing serious disease in immune compromised individuals and in congenitally infected children. Improved methods are needed for prevention and control of HCMV infections. One path for development of novel antiviral agents begins with identification and exploitation of novel intersections between virus and cell biology. An example of this is that HCMV encodes several seven-transmembrane (7TM) proteins that have sequence properties reminiscent of heptaspanning signaling molecules such as G protein-coupled receptors. One of these, pUS17 (encoded by the US17 gene) is expressed in a segmented manner, with its N-terminal domain localizing to the cytoplasm at the periphery of the cytoplasmic virion assembly compartment, and the C-terminal domain localizing to the center of the assembly compartment and to infected cell nuclei. We hypothesize that pUS17 segmentation is the product of regulated intramembrane proteolysis (RIP), and that the N-terminal and C-terminal pUS17 segments have biological roles during infection. RIP is an important mechanism for cellular regulation, for which there are few viral precedents and for which the cellular mechanisms are not fully understood. Thus, this represents a timely opportunity to use a well-evolved viral system to study a cellular mechanism of general importance, and to define the role of this process in infection, so that this information can be used to devise novel antiviral strategies. Thus, we will identify and characterize the mechanisms by which US17 is segmented. This will include (i) determining the boundaries of the segments (Aim 1), and (ii) identifying whether segment biogenesis is due to a proteolytic, translational, or transcriptional process (Aim 2).The significance of the proposed work rests on our identification of a novel mode of intracellular regulation of a virally-encoded 7TM protein that is likely to play an important role in intracellular communication. If there is a proteolysis requirement, this opens a whole new area of antiviral development work. The proposed work will open important new avenues for understanding HCMV biology and its pathogenic mechanisms.