基因素H3.3对于胚胎干细胞内源性逆转录病毒元素沉默是必需的
Simon J Elsässer1,2, Kyung-Min Noh3, Nichole Diaz3
1MRC Laboratory of Molecular Biology, Francis Crick Ave, Cambridge, CB2 0QH, United Kingdom.
Nature
|May 5, 2015
概括
基因组变异H3.3控制胚胎干细胞内源性逆转录病毒元素 (ERV) 逆转录. 它的沉积与KAP1和ESET联系在一起,建立了一个独特的异染色体状态,使ERV沉默,防止基因组不稳定.
科学领域:
- 基因组学和表观遗传学
- 分子生物学分子生物学
- 哺乳动物基因组法规 哺乳动物基因组法规
背景情况:
- 可移植元素 (TE) 构成了哺乳动物基因组的很大一部分,有助于遗传变异,但也导致基因组不稳定.
- 内源逆转录病毒元素 (ERVs) 是TEs的一个子集,通常通过ESET和KAP1在小鼠胚胎干细胞中通过基因组素H3氨酸9三甲基化 (H3K9me3) 沉默.
研究的目的:
- 调查子胚胎干细胞中ERVs的调节和沉默中组织蛋白变异H3.3的作用.
- 阐明H3.3沉积,H3K9me3和ERV逆转换之间的关系.
主要方法:
- 染色体免疫沉 (ChIP) 用于评估H3.3,H3K9me3,KAP1,ATRX和DAXX在ERV中的丰富度.
- 在H3.3删除或耗尽后分析ERV和相邻基因表达.
- 对特定ERV家族 (ETn/MusD,IAPs) 的逆转换率的评估.
主要成果:
- 基因组变异H3.3在特定的ERV (I类,II类,ETn/MusD,IAP) 中得到丰富,其沉积取决于ATRX/DAXX伴侣复合体.
- 将DAXX,H3.3和KAP1招募到ERV是相互依赖的,并且在ESET介导的H3K9me3之前,将H3.3与ERV异性染色体形成联系起来.
- 在ERV中,H3.3的枯竭减少了H3K9me3,导致邻近基因的脱抑制,并增加了IAP的逆转换.
结论:
- 在ERVs中发现了一种由H3.3和H3K9me3两种特征的新型异性染色质状态.
- H3.3在控制ERV逆转换和维持胚胎干细胞基因组稳定性方面发挥着关键作用.
- H3.3介导沉默的失调有助于异常的基因表达和潜在的基因组不稳定性.
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