Specific histone tail modification and not DNA methylation is a determinant of herpes simplex virus type 1 latent gene expression
Specific histone tail modification and not DNA methylation is a determinant of herpes simplex virus type 1 latent gene expression
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DOI：
10.1128/jvi.78.3.1139-1149.2004
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发表时间：
2004-02-01
影响因子：
5.4
通讯作者：
Bloom, DC
中科院分区：
文献类型：
--
作者：
Kubat, NJ;Tran, RK;Bloom, DC
在单纯疱疹病毒1型（HSV-1）潜伏期，除了潜伏相关转录本（IAT）外，基因表达受到严格抑制。这种抑制的机制基础尚不清楚，但其整体性质表明通过表观遗传机制（如DNA甲基化）进行调节。之前的工作表明，潜伏的HSV-1基因组并未广泛甲基化，但这些研究缺乏检查单个CpG甲基化的解决方案，这些甲基化可能在潜伏期间抑制单个启动子的转录。为了解决这一点，我们采用已建立的模型来预测甲基化概率最高的基因组区域，并使用亚硫酸氢盐测序分析这些区域的甲基化谱。我们没有发现显着的甲基化从小鼠背根神经节中分离的潜伏DNA在任何检查的区域，包括ICP 4和LAT启动子。该分析表明甲基化不太可能在调节HSV-1潜伏基因表达中起主要作用。随后，我们集中在差异组蛋白修饰作为另一种表观遗传机制，可以调节潜在的转录。染色质免疫沉淀分析的潜伏HSV-1 DNA重复区表明，LAT区域的一部分是与组蛋白H3乙酰化赖氨酸9和14，与常染色质和非抑制结构一致。与此相反，与HSV-1 DNA聚合酶基因位于独特的长片段的染色质中没有丰富的H3乙酰化的赖氨酸9和14，这表明转录失活的结构。这些数据表明，组蛋白组成可能是HSV潜伏期的主要调控决定因素。
During herpes simplex virus type 1 (HSV-1) latency, gene expression is tightly repressed except for the latency-associated transcript (IAT). The mechanistic basis for this repression is unknown, but its global nature suggests regulation by an epigenetic mechanism such as DNA methylation. Previous work demonstrated that latent HSV-1 genomes are not extensively methylated, but these studies lacked the resolution to examine methylation of individual CpGs that could repress transcription from individual promoters during latency. To address this point, we employed established models to predict genomic regions with the highest probability of being methylated and, using bisulfite sequencing, analyzed the methylation profiles of these regions. We found no significant methylation of latent DNA isolated from mouse dorsal root ganglia in any of the regions examined, including the ICP4 and LAT promoters. This analysis indicates that methylation is unlikely to play a major role in regulating HSV-1 latent gene expression. Subsequently we focused on differential histone modification as another epigenetic mechanism that could regulate latent transcription. Chromatin immuno-precipitation analysis of the latent HSV-1 DNA repeat regions demonstrated that a portion of the LAT region is associated with histone H3 acetylated at lysines 9 and 14, consistent with a euchromatic and nonrepressed structure. In contrast, the chromatin associated with the HSV-1 DNA polymerase gene located in the unique long segment was not enriched in H3 acetylated at lysines 9 and 14, suggesting a transcriptionally inactive structure. These data suggest that histone composition may be a major regulatory determinant of HSV latency.