The Role of PIAS1 in EBV Biology

项目摘要 EB病毒（EBV）感染95%的人类，并导致所有人类癌症的1-2%。到 迄今为止，还没有特定的治疗方法来根除与这种病毒有关的癌症。成功 开发EBV特异性抗癌策略需要深入了解其分子机制， 控制病毒潜伏和再激活的机制。目前，我们的国家存在着根本性的差距， 了解细胞因子如何控制EBV潜伏期和再激活。这项研究的中心目标是 本研究旨在阐明活化的STAT 1蛋白抑制剂（PIAS 1）在EBV生命周期中的作用。 我们最近的研究表明，PIAS 1是一种EBV限制因子，可抑制病毒从潜伏期再激活。我们 已经证明PIAS 1通过半胱天冬酶裂解，并在裂解后被EBV蛋白激酶磷酸化 这是EBV复制所必需的。控制裂解性EBV复制的机制是 与PIAS 1抑制病毒和细胞转录因子的转录活性的能力相关， 用于裂解基因表达。此外，PIAS 1还调节一组宿主基因的表达，这些基因参与了 胆固醇生物合成过程，一个重要的途径EBV裂解复制。这些结果导致我们的中央 假设PIAS 1通过抑制病毒和细胞转录因子限制EBV裂解性复制， PIAS 1被胱天蛋白酶依赖性切割和病毒激酶介导的磷酸化拮抗，以促进细胞溶解。 复制的 针对这一假设，我们建议追求两个具体目标： 目的1：探讨PIAS 1抑制EBV裂解性复制的机制。我们将确定 并验证感染细胞中EBV和宿主基因组上的PIAS 1结合位点。我们将确定PIAS 1 通过抑制病毒和细胞转录因子调节EBV裂解基因表达。我们还将确定 PIAS 1如何通过调节胆固醇生物合成途径部分抑制EBV再活化。 目的2：阐明PIAS 1介导的抑制被拮抗以促进PIAS 1表达的机制。 EBV裂解性复制。PIAS 1被caspase-3、-6和-8切割，并被EBV蛋白激酶磷酸化 在裂解复制过程中。我们将使用蛋白质组学和分子方法鉴定PIAS 1磷酸化位点。 我们将阐明促进EBV复制的磷酸化和裂解PIAS 1之间的相互作用。 我们提出的研究将大大提高我们对PIAS 1作为一个限制因素， 调节EBV感染以及PIAS 1在再活化期间如何受病毒和细胞因子调节。这些 研究将有可能阐明EBV裂解性再激活的分子基础， 宿主因子

PROJECT SUMMARY Epstein-Barr virus (EBV) infects 95% of the human population and contributes to 1-2% of all human cancers. To date, there are no specific therapies to eradicate cancers associated with this virus. The successful development of EBV-specific anti-cancer strategies requires an in-depth understanding of the molecular mechanism controlling viral latency and reactivation. Currently, there are fundamental gaps in our understanding of how cellular factors control EBV latency and reactivation. The central goal of this research program is to elucidate the role of protein inhibitor of activated STAT1 (PIAS1) in the EBV life cycle. Our recent study revealed that PIAS1 is an EBV restriction factor that inhibits virus reactivation from latency. We have demonstrated that PIAS1 is cleaved via caspases and phosphorylated by an EBV protein kinase upon lytic induction and that this is required for EBV replication. The mechanism for controlling lytic EBV replication is related to the ability of PIAS1 to inhibit the transcriptional activity of viral and cellular transcription factors critical for lytic gene expression. In addition, PIAS1 also regulates the expression of a group host genes involved in the cholesterol biosynthesis process, a pathway important for EBV lytic replication. These results lead to our central hypothesis that PIAS1 restricts EBV lytic replication by inhibiting viral and cellular transcription factors, and that PIAS1 is antagonized by caspase-dependent cleavage and viral kinase-mediated phosphorylation to foster lytic replication. Towards this hypothesis, we propose to pursue two Specific Aims: AIM 1: To determine the mechanisms by which PIAS1 suppresses EBV lytic replication. We will identify and validate PIAS1 binding sites on the EBV and host genomes in infected cells. We will determine how PIAS1 regulates EBV lytic gene expression via inhibiting viral and cellular transcription factors. We will also determine how PIAS1 inhibits EBV reactivation partially through modulating the cholesterol biosynthesis pathway. Aim 2: To elucidate the mechanisms by which PIAS1-mediated suppression is antagonized to facilitate EBV lytic replication. PIAS1 is cleaved by caspase-3, -6 and -8, and phosphorylated by an EBV protein kinase during lytic replication. We will identify PIAS1 phosphorylation sites using proteomic and molecular approaches. We will elucidate the interplay between the phosphorylation and cleavage PIAS1 that facilitates EBV replication. Our proposed research will significantly improve our understanding of how PIAS1, as a restriction factor, regulates EBV infection and how PIAS1 is regulated by viral and cellular factors during reactivation. These studies will have the potential to illuminate the molecular basis of EBV lytic reactivation controlled by one central host factor.