Visualization of the Drosophila dKeap1-CncC interaction on chromatin illumines cooperative, xenobiotic-specific gene activation
Visualization of the Drosophila dKeap1-CncC interaction on chromatin illumines cooperative, xenobiotic-specific gene activation
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DOI：
10.1242/dev.110528
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发表时间：
2014-08-01
期刊：
影响因子：
4.6
通讯作者：
Kerppola, Tom K.
中科院分区：
文献类型：
--
作者：
Deng, Huai;Kerppola, Tom K.
转录因子之间的相互作用通过调节它们的结合特异性和转录活性来控制它们的生理功能。我们实施了一种策略，直接可视化果蝇单个细胞中由多蛋白复合体结合的基因组位置。该方法基于多线染色体上蛋白质相互作用的双分子荧光互补(BIFC)分析。果蝇Keap1(DKeap1)-CNCC复合体定位于细胞核，并与dKeap1或CNCC分开表达时不优先结合的染色质基因座结合。苯巴比妥可增强dKeap1与CNCC的结合，而叔丁基对苯二酚(TBHQ)和百草枯则无此作用。内源性dKeap1和CNCC激活了Jheh(Jheh1，Jheh2，Jheh3)和dKeap1基因在这些位点的转录，而CNCC单独激活了其他异源反应基因。异位表达的dKeap1增加了Jheh和dKeap1基因的CNCC结合并激活了它们的转录，而dKeap1抑制了其他异种反应基因的CNCC结合并抑制了它们的转录。DKeap1-CNCC复合体结合染色质的特异性和转录活性介导了不同外源化合物对不同基因的选择性激活，部分是通过dKeap1转录的前馈激活。
Interactions among transcription factors control their physiological functions by regulating their binding specificities and transcriptional activities. We implement a strategy to visualize directly the genomic loci that are bound by multi-protein complexes in single cells in Drosophila. This method is based on bimolecular fluorescence complementation (BiFC) analysis of protein interactions on polytene chromosomes. Drosophila Keap1 (dKeap1)-CncC complexes localized to the nucleus and bound chromatin loci that were not bound preferentially by dKeap1 or CncC when they were expressed separately. dKeap1 and CncC binding at these loci was enhanced by phenobarbital, but not by tert-butylhydroquinone (tBHQ) or paraquat. Endogenous dKeap1 and CncC activated transcription of the Jheh (Jheh1, Jheh2, Jheh3) and dKeap1 genes at these loci, whereas CncC alone activated other xenobiotic response genes. Ectopic dKeap1 expression increased CncC binding at the Jheh and dKeap1 gene loci and activated their transcription, whereas dKeap1 inhibited CncC binding at other xenobiotic response gene loci and suppressed their transcription. The combinatorial chromatin-binding specificities and transcriptional activities of dKeap1-CncC complexes mediated the selective activation of different sets of genes by different xenobiotic compounds, in part through feed-forward activation of dKeap1 transcription.