Control of Translation in Herpesvirus infected Cells

描述（由申请人提供）：真核细胞对多种形式的应激（从热不耐受或营养缺乏到病毒感染）作出反应的能力部分涉及它们调节eIF 2（一种关键的翻译起始因子）活性的能力。在其α亚基上被四种已知的eIF 2 α激酶之一磷酸化后，eIF 2失活并且翻译被抑制。该项目的总体长期目标是了解eIF 2 α磷酸化是如何响应于病毒感染产生的应激而调节的。在受感染的细胞中，许多细胞功能的挪用和重定向加上病毒基因产物的快速积累会诱导细胞应激并激活宿主防御。在病毒感染的细胞中产生的大量双链（ds）RNA激活细胞eIF 2 α激酶PKR，而病毒糖蛋白的合成增加内质网上的负荷，超过其正确折叠和加工ER客户蛋白的能力。后一种情况触发未折叠蛋白反应（UPR），随后eIF 2 α的磷酸化阻止翻译。 在这个提议中，我们调查病毒策略，防止宿主防御失活的翻译因子elF 2。我们的研究集中在单纯疱疹病毒-1，一种神经营养性疱疹病毒，其生产性复制是负责一系列疾病，从上皮溃疡，严重的眼部疾病和危及生命的脑炎在免疫功能正常的主机传播疾病的新生儿和免疫功能低下的个人。已知gamma（1）34.5和Us 11基因产物均调节eIF 2 α磷酸化。虽然γ（1）34.5基因产物募集细胞磷酸酶以使eIF 2 α去磷酸化，但Us 11通过未知机制阻止细胞eIF 2 α激酶PKR的活化。此外，HSV-1表达一种以前未表征的功能，不同于Us 11和gamma（1）34.5基因的多肽产物，其赋予对ER应激的抗性。我们将（i）评估HSV-1感染对ER应激转导物的影响;（ii）鉴定负责防止eIF 2 α磷酸化的基因产物，以响应刺激UPR的效应物;和（iii）研究Us 11防止PKR活化的分子机制。

DESCRIPTION (provided by applicant): The capacity of eukaryotic cells to respond to numerous forms of stress, ranging from thermal intolerance or nutrient deprivation to viral infection, involves, in part, their ability to regulate the activity of elF2, a critical translation initiation factor. Upon phosphorylation on it's alpha subunit by one of four known elF2alpha kinases, elF2 is inactivated and translation is inhibited. The overall long - term objective of this project is to understand how elF2alpha phosphorylation is regulated in response to stress generated by viral infection. In infected cells, the appropriation and redirection of many cellular functions coupled with the rapid accumulation of viral gene products induces cellular stress and activates host defenses. Copious quantities of double stranded (ds)RNA produced in virus infected cells activates the cellular elF2alpha kinase PKR, while the synthesis of viral glycoproteins increases the load on the endoplasmic reticulum, exceeding its capacity to correctly fold and process ER client proteins. This latter condition triggers the unfolded protein response (UPR) and the ensuing phosphorylation of elF2alpha arrests translation. In this proposal, we investigate viral strategies that prevent host defenses from inactivating the translation factor elF2. Our studies focus on herpes simplex virus-1, a neurotrophic herpesvirus whose productive replication is responsible for a spectrum of diseases, ranging from epithelial sores, severe ocular disease and life threatening encephalitis in immunocompetent hosts to disseminated disease in neonates and immunocompromised individuals. Both the gamma(1)34.5 and Us11 gene products are known to regulate elF2alpha phosphorylation. While the gamma(1)34.5 gene product recruits a cellular phosphatase to dephosphorylate elF2alpha, Us11 prevents activation of the cellular elF2alpha kinase PKR via an unknown mechanism. Furthermore, HSV-1 expresses a previously uncharacterized function, distinct from the polypeptide products of the Us11and gamma(1)34.5 genes, that confers resistance to ER stress. We will (i) evaluate the effects of HSV-1 infection on ER stress transducers; (ii) identify the gene product (s) responsible for preventing elF2alpha phosphorylation in response to effectors that stimulate the UPR; and (iii) investigate the molecular mechanisms by which Us11 prevents PKR activation.