Modulation of a transcription factor counteracts heterochromatic gene silencing in Drosophila
Modulation of a transcription factor counteracts heterochromatic gene silencing in Drosophila
复制标题
DOI：
10.1016/s0092-8674(01)00281-1
复制
发表时间：
2001-03-23
期刊：
影响因子：
64.5
通讯作者：
Henikoff, S
中科院分区：
文献类型：
--
作者：
Ahmad, K;Henikoff, S
杂色是基因沉默现象的一个共同特征，但随机开/关表达的基础是未知的。我们使用了一个条件系统，允许探测异染色质在报告GFP基因通过改变GAL 4转录因子水平在果蝇眼睛发育。令人惊讶的是，基因沉默的频率对GAL 4水平非常敏感，就好像结合位点的占用影响沉默状态一样。沉默状态是可塑的，因为自发的去抑制偶尔发生在有丝分裂活跃和分化的细胞中。通过同时测定附近基因的表达，我们进一步表明异染色质内激活区域的大小很小。我们认为杂色的发生是因为异染色质抑制了因子结合位点的瞬时暴露。
Variegation is a common feature of gene silencing phenomena, yet the basis for stochastic on/off expression is unknown. We used a conditional system that allows probing of heterochromatin at a reporter GFP gene by altering GAL4 transcription factor levels during Drosophila eye development. Surprisingly, the frequency of gene silencing is exquisitely sensitive to GAL4 levels, as though binding site occupancy affects the silenced state. The silent state is plastic, as spontaneous derepression occasionally occurs in both mitotically active and differentiating cells. By simultaneously assaying expression of a nearby gene, we further show that the size of an activated region within heterochromatin is small. We propose that variegation occurs because heterochromatin inhibits the transient exposure of factor binding sites.