Chromatin-dependent E1A activity modulates NF-κB RelA-mediated repression of glucocorticoid receptor-dependent transcription
Chromatin-dependent E1A activity modulates NF-κB RelA-mediated repression of glucocorticoid receptor-dependent transcription
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DOI：
10.1074/jbc.m411147200
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发表时间：
2005-02-25
影响因子：
4.8
通讯作者：
Archer, TK
中科院分区：
文献类型：
--
作者：
Burkhart, BA;Hebbar, PB;Archer, TK
利用染色质和瞬时转染的报告基因研究了染色质依赖的调控机制在p65和E1 A抑制小鼠乳腺肿瘤病毒（MMTV）启动子糖皮质激素依赖的转录中的作用。NF-κ B的p65 RelA亚基抑制MMTV在瞬时或整合报告基因上的表达。相反，病毒癌蛋白E1 A抑制一个短暂的，但不是一个集成的MMTV。E1 A的阻遏被染色质减弱，这表明p65而不是E1 A适当地操纵染色质以抑制GR。p65和E1 A的共表达额外地抑制了瞬时NMTV，但恢复了响应于糖皮质激素的染色质MMTV的转录激活。这表明E1 A具有减弱p65抑制的主要染色质依赖性活性。E1 A、p65和GR与MMTV启动子结合，染色质重塑增强了与受抑制和活化启动子的结合。此外，p65需要Brg来抑制整合的NMTV。这表明p65抑制和E1 A抑制的减弱都不是由阻止转录因子结合的重塑抑制引起的。此外，p300/CBP也是p65和E1 A抑制和减弱所必需的。不结合p300/CBP的E1 A和p65突变体是无活性的，这表明需要p300/CBP依赖性复合物的形成来抑制和减弱染色质。这些数据表明，无论是p65依赖性抑制和E1 A介导的抑制衰减需要Brg 1依赖性染色质重塑功能和p300/CBP依赖性复合物的形成在启动子组装在染色质内。
The role of chromatin-dependent regulatory mechanisms in the repression of glucocorticoid-dependent transcription from the murine mammary tumor virus (MMTV) promoter by p65 and E1A was investigated by using chromatin and transiently transfected reporters. The p65 RelA subunit of NF-kappaB represses MMTV expression on either transient or integrated reporters. In contrast, the viral oncoprotein E1A represses a transient but not an integrated MMTV. E1A repression is attenuated by chromatin, suggesting p65 but not E1A manipulates chromatin appropriately to inhibit the GR. Coexpression of p65 and E1A additively represses the transient NMTV but restores the transcriptional activation of the chromatin MMTV in response to glucocorticoids. This indicates that E1A has a dominant chromatin-dependent activity that attenuates repression by p65. E1A, p65, and GR bind the MMTV promoter, and chromatin remodeling enhances binding on both repressed and activated promoters. In addition, p65 requires Brg for repression of the integrated NMTV. This suggests that neither p65 repression nor E1A attenuation of repression results from an inhibition of remodeling that prevents transcription factor binding. Furthermore, p300/CBP is also required for both repression and attenuation by p65 and E1A. E1A and p65 mutants that do not bind p300/CBP are inactive, indicative of a requirement for p300/CBP-dependent complex formation for both repression and attenuation with chromatin. These data suggest that both the p65-dependent repression and the E1A-mediated attenuation of repression require the Brg1 dependent chromatin remodeling function and p300/CBP-dependent complex formation at a promoter assembled within chromatin.