Histone modifications are associated with the persistence or silencing of vector-mediated transgene expression in vivo
Histone modifications are associated with the persistence or silencing of vector-mediated transgene expression in vivo
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DOI：
10.1038/sj.mt.6300177
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发表时间：
2007-07-01
影响因子：
12.4
通讯作者：
Kay, Mark A.
中科院分区：
文献类型：
--
作者：
Riu, Efren;Chen, Zhi-Ying;Kay, Mark A.
非病毒基因治疗成功的主要障碍之一是DNA载体的转录沉默。哺乳动物细胞中基因沉默/抑制的潜在机制是复杂的，并且仍然不清楚。由于染色质结构的变化，特别是组蛋白修饰参与内源性基因的转录调控，我们假设组蛋白修饰模式的变化与观察到的外源性DNA载体的转录沉默有关。我们使用针对特定修饰组蛋白的抗体对用两种类型质粒转染的小鼠的肝裂解物进行染色质免疫沉淀（ChIP）分析：（i）缺乏细菌质粒骨架DNA的DNA微环（MC），其显示转基因表达的显著持续性，和（ii）其亲本质粒，其随时间沉默。来自亲本载体的转基因沉默伴随着异染色质相关组蛋白修饰的增加和通常与常染色质相关的修饰的减少。相反，MC DNA上的组蛋白修饰模式与常染色质一致。我们的数据表明，（i）附加型载体在体内经历染色质化，和（ii）转基因表达的持续和沉默都与特定的组蛋白修饰有关。
One of the major obstacles to success in non-viral gene therapy is transcriptional silencing of the DNA vector. The mechanisms underlying gene silencing/repression in mammalian cells are complex and remain unclear. Because changes in chromatin structure and, in particular, histone modifications are involved in transcriptional regulation of endogenous genes, we hypothesized that changes in the pattern of histone modifications were related to the observed transcriptional silencing of exogenous DNA vectors. We used antibodies against specific modified histones to perform chromatin immunoprecipitation (ChIP) analyses on liver lysates from mice transfected with two types of plasmids: (i) DNA minicircles (MCs) devoid of bacterial plasmid backbone DNA, which showed marked persistence of transgene expression, and (ii) their parental plasmids, which were silenced over time. Silencing of the transgene from the parental vectors was accompanied by an increase in heterochromatin-associated histone modifications and a decrease in modifications typically associated with euchromatin. Conversely, the pattern of histone modifications on the MC DNA was consistent with euchromatin. Our data indicates that (i) episomal vectors undergo chromatinization in vivo, and (ii) both persistence and silencing of transgene expression are associated with specific histone modifications.