KSHV RTA: more than viral replication

描述(申请人提供)：自从它们存在以来，病毒和它们的宿主细胞之间就一直在进行着一场无休止的军备竞赛。宿主细胞已经开发出许多策略来抑制病毒基因的表达，而病毒总是能找到克服这些障碍的方法。因此，病毒已经进化到充分利用现有的细胞染色质成分，在需要时激活或抑制自己的基因。事实上，宿主对疱疹病毒基因组染色质的表观遗传修饰在病毒产生的生命周期中对潜伏和裂解基因的转录控制起着关键作用。Kaposi肉瘤相关疱疹病毒(KSHV)是一种普遍存在的疱疹病毒，可在人类中建立终身持续感染，并与Kaposi肉瘤和几种淋巴系统恶性肿瘤有关。在潜伏期，KSHV基因组以组装成核小体结构的多拷贝环状DNA形式持续存在。虽然病毒潜伏期的特征是限制病毒基因的表达，但重新激活会诱导裂解复制程序，并以确定的顺序和时间顺序表达病毒基因。我们的初步研究表明：(1)KSHV的潜染色质和裂解染色质与激活和抑制组蛋白修饰的独特模式有关，其分布在重新激活后以有组织的方式发生变化，与病毒裂解基因的时间有序表达相关。此外，进化上保守的Polycomb group蛋白和组蛋白去泛素酶也通过调节病毒染色质结构在调节KSHV潜伏期和重新激活过程中发挥关键作用。因此，KSHV的表观遗传程序是限制潜伏基因表达和裂解基因有序表达的关键。本研究的目的是更好地了解KSHV基因组的表观遗传修饰如何影响病毒的潜伏期和裂解复制，从而促进持续感染的发展和体内随后的致病事件。根据我们的初步研究，我们假设KSHV基因组的适当表观遗传调节对于病毒在潜伏和重新激活期间的持久性以及对KSHV感染皮损的致病至关重要。这一建议是高度创新的，利用了成熟的全面全基因组芯片阵列、BAC遗传学和体内实验条件。

DESCRIPTION (provided by applicant): Ever since their existence, there has been an everlasting arms race between viruses and their host cells. Host cells have developed numerous strategies to silence viral gene expression, whereas viruses always find ways to overcome these obstacles. Accordingly, viruses have evolved to take full advantage of existing cellular chromatin components to activate or repress its own genes when needed. In fact, host epigenetic modifications of the herpesviral genome chromatin play a key role in the transcriptional control of latent and lytic genes during a productive viral lifecycle. Kaposi's sarcoma-associated herpesvirus (KSHV) is a ubiquitous herpesvirus that establishes a life-long persistent infection in humans and is associated with Kaposi's sarcoma and several lymphoid malignancies. During latency, the KSHV genome persists as a multicopy circular DNA assembled into nucleosomal structures. While viral latency is characterized by restricted viral gene expression, reactivation induces the lytic replication program and the expression of viral genes in a defined sequential and temporal order. Our preliminary study demonstrates that (1) the latent and lytic chromatins of KSHV are associated with a distinctive pattern of activating and repressive histone modifications whose distribution changes upon reactivation in an organized manner in correlation with the temporally ordered expression of viral lytic genes. Furthermore, (2) the evolutionarily conserved Polycomb group proteins and histone deubiquitinases also play a critical role in the regulation of KSHV latency and reactivation by regulating the viral chromatin structure. Thus, the epigenetic program of KSHV is at the crux of restricting latent gene expression and the orderly expression of lytic genes. The goal of this study is to better understand how epigenetic modifications of the KSHV genome affect viral latency and lytic replication, to thereby contribute to the development of a persistent infection and subsequent pathogenic events in vivo. Based on our preliminary studies, we hypothesize that the proper epigenetic regulation of the KSHV genome is critical for viral persistency during latency and reactivation, and for pathogenesis in KSHV infected lesions. This proposal is highly innovative, utilizing well-established comprehensive genome-wide ChIP array, BAC genetics, and in vivo experimental conditions.