Epigenetic Modulation of Gene Expression from Quiescent Herpes Simplex Virus Genomes
Epigenetic Modulation of Gene Expression from Quiescent Herpes Simplex Virus Genomes
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DOI：
10.1128/jvi.00785-09
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发表时间：
2009-09-01
影响因子：
5.4
通讯作者：
DeLuca, Neal A.
中科院分区：
文献类型：
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作者：
Ferenczy, Michael W.;DeLuca, Neal A.
单纯疱疹病毒在细胞中持续存在的能力取决于病毒基因表达的程度，这可能受表观遗传机制控制。我们使用静止感染的病毒突变体d109和d106，探讨细胞类型和存在的病毒蛋白ICP0的表达和染色质结构的人巨细胞病毒（HCMV）tk和gC启动子的病毒基因组上的影响。HCMV启动子在d109基因组上的表达随着时间的推移而降低，并且在HEL细胞中比在Vero细胞中少得多。在d106中从HCMV启动子的表达比在d109中更丰富，并且这在两种细胞类型中随时间增加。在病毒基因组上的tk和gC基因上观察到相同的表达模式，尽管在d106和d109中tk和gC RNA的水平分别比野生型病毒低约10（2）倍和10（5）倍。在微球菌核酸酶消化实验中，核小体在d109基因组上是明显的，并且通过染色质免疫沉淀法测定的总H3的量在d109上比d106基因组大得多。在Vero细胞中，组蛋白H3在d106基因组上的乙酰化在感染后的早期和晚期是明显的，但在HEL细胞中仅在晚期。对于在赖氨酸9上乙酰化的H3观察到相同的模式。三甲基化的H3K9 d109基因组是明显的，只有在晚期感染后在Vero细胞，而它被观察到早期和晚期在HEL细胞。异染色质蛋白1 γ（HP1 γ）一般只存在于d109基因组在感染后的晚期HEL细胞。染色质结构的观察结果与静止基因组上的三个分析基因的表达模式相关。因此，几种机制通常影响表达并有助于持续基因组的沉默。它们是核小体的丰度、组蛋白的乙酰化状态和异染色质。这些不同的机制在不同的细胞类型中对抑制的贡献程度不同，并且被ICP0的存在所抵消。
The ability of herpes simplex virus to persist in cells depends on the extent of viral-gene expression, which may be controlled by epigenetic mechanisms. We used quiescent infection with the viral mutants d109 and d106 to explore the effects of cell type and the presence of the viral protein ICP0 on the expression and chromatin structure of the human cytomegalovirus (HCMV) tk and gC promoters on the viral genome. Expression from the HCMV promoter on the d109 genome decreased with time and was considerably less in HEL cells than in Vero cells. Expression from the HCMV promoter in d106 was considerably more abundant than in d109, and this increased with time in both cell types. The same pattern of expression was seen on the tk and gC genes on the viral genomes, although the levels of tk and gC RNA were approximately 10(2)- and 10(5)-fold lower than those of wild-type virus in d106 and d109, respectively. In micrococcal-nuclease digestion experiments, nucleosomes were evident on the d109 genome, and the amount of total H3 as determined by chromatin immunoprecipitation was considerably greater on d109 than d106 genomes. The acetylation of histone H3 on the d106 genomes was evident at early and late times postinfection in Vero cells, but only at late times in HEL cells. The same pattern was observed for H3 acetylated on lysine 9. Trimethylation of H3K9 on d109 genomes was evident only at late times postinfection in Vero cells, while it was observed both early and late in HEL cells. Heterochromatin protein 1 gamma (HP1 gamma) was generally present only on d109 genomes at late times postinfection of HEL cells. The observations of chromatin structure correlate with the expression patterns of the three analyzed genes on the quiescent genomes. Therefore, several mechanisms generally affect the expression and contribute to the silencing of persisting genomes. These are the abundance of nucleosomes, the acetylation state of the histones, and heterochromatin. The extents to which these different mechanisms contribute to repression vary in different cell types and are counteracted by the presence of ICP0.