Chromatin and Coactivators in HSV-1 gene regulation

描述（由申请人提供）：真核基因组包装在染色质中，染色质是一种含有DNA、组蛋白和非组蛋白染色体蛋白的核蛋白复合物。由此提供的压实对需要接近模板DNA的细胞过程如复制和转录呈现显著的障碍。感染真核细胞的DNA病毒是研究染色质对基因调控和复制的影响的有用实验对象。HSV-1的VP 16蛋白有效地刺激病毒立即早期基因的转录，从而在裂解性感染周期中触发病毒基因表达的级联反应。在异源实验环境中，VP 16可以募集染色质修饰共激活因子以靶向启动子。然而，先前的报道表明，大HSV-1病毒DNA基因组在裂解感染期间主要保持非核小体。这些观察揭示了一个明显的悖论：为什么像VP 16这样的病毒激活因子会将染色质修饰辅激活蛋白招募到缺乏核小体的DNA模板上？本项目的总体目标是确定组蛋白和染色质在HSV-1基因调控中的作用，包括感染期间病毒基因上染色质修饰辅激活蛋白的募集和活性。迄今为止，我们的工作表明，某些辅激活因子在HSV感染期间确实以依赖于VP 16激活结构域的方式与病毒DNA结合。此外，组蛋白存在于病毒DNA的许多区域，但以VP 16依赖性方式不存在于IE启动子中。在拟定的项目期间，将检测在整个裂解感染过程中其他组蛋白和非组蛋白染色体蛋白与HSV DNA的相关性。将检查IE启动子处其他共激活蛋白的存在，以及IE转录对这些共激活蛋白的依赖性。这项工作将促进对细胞调控机制的理解，以及HSV用于适应病毒基因表达的机制的策略。 单纯疱疹病毒感染在美国人群中广泛存在，并导致严重不适和偶尔死亡。病毒感染的早期阶段似乎依赖于宿主细胞的某些酶。这项研究将验证这些酶在病毒感染中的作用，这可能导致新的抗病毒药物靶点。

DESCRIPTION (provided by applicant): Eukaryotic genomes are packaged in chromatin, a nucleoprotein complex containing DNA, histones, and nonhistone chromosomal proteins. The compaction thus provided presents a significant barrier to cellular processes such as replication and transcription that require access to template DNA. DNA viruses that infect eukaryotic cells have served as useful experimental subjects for studying effects of chromatin on gene regulation and replication. The VP16 protein of HSV-1 potently stimulates transcription of the viral immediate early genes and thus triggers the cascade of viral gene expression during the lytic infection cycle. In heterologous experimental contexts, VP16 can recruit chromatin modifying coactivators to target promoters. However, previous reports indicated that the large HSV-1 viral DNA genome remains predominantly non-nucleosomal during lytic infection. These observations reveal an apparent paradox: why would a viral activator such as VP16 recruit chromatin modifying coactivator proteins to a DNA template that lacks nucleosomes? The overall goal of this project is to define the roles of histones and chromatin in HSV-1 gene regulation, including the recruitment and activity of chromatin-modifying coactivator proteins on viral genes during infection. Our work to date has shown that certain coactivators do associate with viral DNA during HSV infection in a manner dependent on the VP16 activation domain. Moreover, histones are present at many regions of the viral DNA, but are absent from IE promoters in a VP16-dependent manner. In the proposed project period, the association of additional histones and nonhistone chromosomal proteins with HSV DNA throughout lytic infection will be tested. The presence of other coactivator proteins at IE promoters will be examined, as will the dependence of IE transcription on those coactivators. This work will advance the understanding of cellular regulatory mechanisms and the strategies used by HSV to adapt those mechanisms for viral -gene expression. Herpes simplex virus infections are widespread in the US population, and cause significant discomfort and occasional death. Early stages in virus infection seem to depend on certain enzymes from the host cell. This research will validate the roles of those enzymes in virus infection, which may lead to new antiviral drug targets.