Mechanisms of KSHV post-transcriptional gene regulation

描述（由申请人提供）：病毒利用广泛的分子机制在受感染宿主细胞的复杂环境中促进自身基因表达。最近的进展表明，病毒对细胞RNA衰变途径的调节比以前所认识的更为普遍。例如，卡波西肉瘤相关疱疹病毒（KSHV）中的几个因子已被证明可以调节宿主或病毒的RNA周转率。在本研究中，我们研究了KSHV ORF57蛋白在病毒转录物稳定性中的作用。ORF57是一种裂解相蛋白，对病毒复制至关重要，据报道，ORF57影响mRNA生物发生中的多种核事件，但其分子机制尚不清楚。本提案中的实验旨在验证ORF57与核RNA结合并保护它们免受细胞RNA衰变途径的假设。具体而言，本文将通过以下研究来阐明ORF57核功能的分子机制：1)ORF57对病毒mrna核稳定性的影响；2)RNA结合与ORF57功能的关系；3)ORF57 RNA结合和稳定性活性在病毒裂解感染中的作用。了解ORF57的分子机制是理解KSHV生物学的基础，KSHV是卡波西肉瘤、原发性积液性淋巴瘤（PEL）和某些类型的多中心Castleman病（MCD）的病原体。对ORF57分子机制的认识可能会带来新的治疗方法，并加强对控制肿瘤发生的重要途径的认识。因此，通过揭示ORF57的功能机制，这些研究将为这一重要的人类病原体及其人类宿主细胞的生物学提供分子见解。

DESCRIPTION (provided by applicant): Viruses use a wide spectrum of molecular mechanisms to favor their own gene expression in the complex environment of an infected host cell. Recent advances suggest that viral regulation of cellular RNA decay pathways is more common than previously appreciated. For example, several factors in the Kaposi's sarcoma-associated herpesvirus (KSHV) have been demonstrated to regulate host or viral RNA turnover rates. In this proposal, a role for the KSHV ORF57 protein in viral transcript stability is examined. ORF57 is a lytic phase protein that is essential for viral replication and has been reported to affect a wide variety of nuclear events in mRNA biogenesis, but its molecular mechanisms remain unknown. The experiments in this proposal are designed to test the hypothesis that ORF57 binds to nuclear RNAs and protects them from cellular RNA decay pathways. Specifically, the studies described here will elucidate the molecular mechanisms of ORF57 nuclear function by examining 1) the effects of ORF57 on nuclear stability of viral mRNAs, 2) the relationship between RNA binding and ORF57 function, and 3) the roles of ORF57 RNA-binding and stability activities in the context of viral lytic infection. Understanding the molecular mechanism of ORF57 is fundamental to understanding the biology of KSHV, the causative agent for Kaposi's sarcoma, primary effusion lymphoma (PEL), and some types of multicentric Castleman's disease (MCD). An appreciation of ORF57 molecular mechanisms may lead to novel therapeutic approaches and bolster knowledge of the pathways important for controlling tumorigenesis. Thus, by revealing the mechanisms of ORF57 function, these studies will provide molecular insights into this important human pathogen and into the biology of its human host cells. PUBLIC HEALTH RELEVANCE: Kaposi's sarcoma-associated herpesvirus (KSHV) causes several malignancies including Kaposi's sarcoma and certain lymphoproliferative disorders. This proposal examines specific mechanisms of KSHV gene regulation essential for viral replication. A deeper understanding of KSHV gene regulation will lead to a more complete knowledge of this important human pathogen and may reveal aspects of gene regulation in its human host cell.