Occupancy of the Drosophila hsp70 promoter by a subset of basal transcription factors diminishes upon transcriptional activation
Occupancy of the Drosophila hsp70 promoter by a subset of basal transcription factors diminishes upon transcriptional activation
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DOI：
10.1073/pnas.0509063102
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发表时间：
2005-12-13
影响因子：
11.1
通讯作者：
Tora, L
中科院分区：
文献类型：
--
作者：
Lebedeva, LA;Nabirochkina, EN;Tora, L
在果蝇体内hsp70基因启动子中，一般转录因子和其他共激活因子的存在已经通过内源性热休克位点或含有hsp70启动子的转基因的多烯染色体免疫荧光和染色质免疫沉淀进行了检测。这些研究表明，hsp70启动子在热休克前已经被TBP结合蛋白（TBP）和几个TBP相关因子（TAFs）、TFIIB、TFIIF （RAP30）、TFIIH （XPB）、不含TBP / taf复合物（GCN5和TRRAP）以及Mediator复合物亚基13占据。热休克后，热休克转录因子、RNA聚合酶II、XPD、GCN5、TRRAP或Mediator复合物13向hsp70启动子大量募集。令人惊讶的是，在热休克时，TBP、六种不同的TAFs、TFIIB和TFIIF的占据率显著降低，而在相同条件下，这些因子在包含蜕皮激素的位点的占据率没有变化。因此，这些发现揭示了hsp70启动子的转录诱导机制，并进一步表明一般转录因子的启动子占据并不一定反映基因的转录状态。
The presence of general transcription factors and other coactivators at the Drosophila hsp70 gene promoter in vivo has been examined by polytene chromosome immunofluorescence and chromatin immunoprecipitation at endogenous heat-shock loci or at a hsp70 promoter-containing transgene. These studies indicate that the hsp70 promoter is already occupied by TATA-binding protein (TBP) and several TBP-associated factors (TAFs), TFIIB, TFIIF (RAP30), TFIIH (XPB), TBP-free/TAF-containg complex (GCN5 and TRRAP), and the Mediator complex subunit 13 before heat shock. After heat shock, there is a significant recruitment of the heat-shock transcription factor, RNA polymerase II, XPD, GCN5, TRRAP, or Mediator complex 13 to the hsp70 promoter. Surprisingly, upon heat shock, there is a marked diminution in the occupancy of TBP, six different TAFs, TFIIB, and TFIIF, whereas there is no change in the occupancy of these factors at ecdysone-incluced loci under the same conditions. Hence, these findings reveal a distinct mechanism of transcriptional induction at the hsp70 promoters, and further indicate that the apparent promoter occupancy of the general transcriptional factors does not necessarily reflect the transcriptional state of a gene.