ROLE OF CHROMATIN IN HERPES SIMPLEX VIRUS TYPE 1 (HSV-1) GENE REGULATION

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 在其人类宿主的初次感染期间，单纯疱疹病毒1型（HSV-1）在神经元中建立潜伏期，其中病毒基因组以与核小体相关的环状形式维持在染色质构型中。在潜伏期，大多数病毒基因被沉默，尽管对此负责的分子机制尚不清楚。我们假设，神经元因素抑制HSV-1基因的表达在潜伏期。通过对HSV-1 DNA序列进行搜索，确定了位于HSV-1基因ICP 22和ICP 4之间的阻遏元件-1/神经元限制性沉默元件（RE-1/NRSE）。我们预测阻遏元件沉默转录因子/神经元限制性沉默因子（REST/NRSF）调节ICP 22和ICP 4的表达。瞬时共转染表明REST/NRSF抑制两种启动子的活性。与此相反，共转染的REST/NRSF的突变体形式编码的DNA结合结构域的蛋白质导致显着减少抑制。含有具有染色质结构的附加型报告质粒的稳定转化的细胞系表明，REST/NRSF特异性抑制ICP 4启动子，但不抑制ICP 22启动子。REST/NRSF对ICP 4启动子的抑制作用可被组蛋白脱乙酰酶（HDAC）抑制剂曲古抑菌素A（TSA）逆转。此外，染色质免疫沉淀（ChIP）分析表明，辅阻遏物CoREST被募集到ICP 4启动子附近，组蛋白H4的乙酰化在REST/NRSF的存在下减少。由于ICP 4蛋白是HSV-1裂解周期基因的关键反式激活因子，这些结果表明REST/NRSF可能在潜伏期HSV-1基因沉默的建立和/或维持中起重要作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. During primary infection of its human host, Herpes Simplex Virus Type-1 (HSV-1) establishes latency in neurons where the viral genome is maintained in a circular form associated with nucleosomes in a chromatin configuration. During latency, most viral genes are silenced, although the molecular mechanisms responsible for this are unclear. We hypothesized that neuronal factors repress HSV-1 gene expression during latency. A search of the HSV-1 DNA sequence for potential regulatory elements identified a Repressor Element-1/Neuronal Restrictive Silencer Element (RE-1/NRSE) located between HSV-1 genes ICP22 and ICP4. We predicted that the Repressor Element Silencing Transcription Factor/Neuronal Restrictive Silencer Factor (REST/NRSF) regulates expression of ICP22 and ICP4. Transient cotransfection indicated that REST/NRSF inhibited the activity of both promoters. In contrast, cotransfection of a mutant form of REST/NRSF encoding only the DNA-binding domain of the protein resulted in significantly less inhibition. Stably transformed cell lines containing episomal reporter plasmids with a chromatin structure showed that REST/NRSF specifically inhibited the ICP4 promoter, but not the ICP22 promoter. REST/NRSF inhibition of the ICP4 promoter was reversed by histone deacetylase (HDAC) inhibitor Trichostatin A (TSA). Additionally, chromatin immuno-precipitation (ChIP) assays indicated that the corepressor CoREST was recruited to the proximity of ICP4 promoter and that acetylation of histone H4 was reduced in the presence of REST/NRSF. Since the ICP4 protein is a key transactivator of HSV-1 lytic cycle genes, these results suggest that REST/NRSF may have an important role in the establishment and/or maintenance of HSV-1 gene silencing during latency.