Modulation and Utilization of RNA Polymerase III by Herpes Simplex Virus

单纯疱疹病毒的基因组除了编码大量非编码RNA外，还编码约90种蛋白质编码基因的mRNA。这些基因的集合通过RNA pol II以顺序方式转录。其表达的时机取决于其启动子中细胞转录因子的顺式作用位点、其对病毒转录因子的需求以及病毒DNA复制的状态。多种病毒蛋白修饰或隔离pol II转录机制的元件，以使病毒基因组的稳健转录成为可能，从而减弱细胞mRNA转录。我们已经发现RNA pol III及其一些转录因子也与HSV基因组结合。RNA pol III转录tRNA和其他细胞非编码RNA。我们还表明，方面的结合的聚合酶III的病毒基因组是相似的，所看到的聚合酶II方面的要求病毒激活剂和病毒DNA复制的效果。然而，与pol II不同，我们发现特定细胞pol III转录单位（即tRNA基因）的转录通过感染而增加。我们假设RNA pol III在HSV基因组上发挥转录非编码RNA的功能，并且pol III在基因组上的功能受到一些调节pol II基因组转录的相同顺式和反式作用元件的调节。我们进一步假设HSV感染通过改变与细胞pol III启动子结合的pol III转录因子的丰度或活性来诱导特定类型的pol III转录。提出了两个具体的目标，以解决这些假设。我们将确定pol III与HSV基因组和由此产生的pol III转录物相关的基础，并确定HSV如何影响细胞pol III转录。其他DNA病毒编码pol III转录本;然而，这是第一项研究表明pol III与HSV基因组相关。可能已知的HSV非编码RNA或尚未发现的非编码RNA由pol III转录。还已知其它病毒刺激pol III转录。HSV对pol III转录的激活可以促进病毒基因组的pol III转录，正如其对腺病毒或EBV所做的那样，和/或提供用于翻译病毒蛋白编码mRNA的最佳水平的tRNA。这项探索性资助将确定感染细胞的病毒和细胞RNA pol III转录组，以及病毒感染调节pol III转录的机制，作为更深入研究pol III与HSV相互作用及其对病毒感染意义的前奏。

The genome of herpes simplex virus encodes mRNAs for about 90 protein coding genes in addition to numerous noncoding RNAs. Sets of these genes are transcribed in a sequential manner by RNA pol II. The timing of their expression is dependent on the cis-acting sites for cellular transcription factors in their promoters, their requirements for virus transcription factors, and the state of viral DNA replication. Multiple viral proteins modify or sequester elements of the pol II transcription machinery to enable the robust transcription of the viral genome, which consequently attenuates cellular mRNA transcription. We have found that RNA pol III and some of its transcription factors also bind to the HSV genome. RNA pol III transcribes tRNAs and other cellular non-coding RNAs. We also show that aspects of the binding of pol III to the viral genome are similar to those seen for pol II with respect to the requirement for viral activators and the effect of viral DNA replication. However, unlike with pol II, we find that the transcription of specific cellular pol III transcription units, namely tRNA genes, is increased by infection. We hypothesize that RNA pol III is functioning on the HSV genome to transcribe noncoding RNAs, and that the function of pol III on the genome is regulated by some of the same cis- and trans- acting elements that regulate pol II transcription of the genome. We further hypothesize that HSV infection induces a specific type of pol III transcription by altering the abundance or activity of the pol III transcription factors that bind to cellular pol III promoters. Two specific aims are proposed to address these hypotheses. We will determine the basis for the association of pol III with the HSV genome and the resulting pol III transcripts, and determine how HSV affects cellular pol III transcription. Other DNA viruses encode pol III transcripts; however, this is the first study to show that pol III associates with the HSV genome. It may be that known HSV noncoding RNAs, or yet to be discovered noncoding RNAs, are transcribed by pol III. Other viruses are also known to stimulate pol III transcription. The activation of pol III transcription by HSV may promote the pol III transcription of the viral genome as it does for adenovirus or EBV, and/or provide for the optimal levels of tRNAs for the translation of viral protein coding mRNAs. This exploratory grant will determine the viral and cellular RNA pol III transcriptome of infected cells, and the mechanisms by which virus infection modulates pol III transcription as prelude to a more in depth investigation of the interaction of pol III with HSV and its significance for viral infection.