ATP-dependent mobilization of the glucocorticoid receptor during chromatin remodeling
ATP-dependent mobilization of the glucocorticoid receptor during chromatin remodeling
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DOI：
10.1128/mcb.22.10.3255-3263.2002
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发表时间：
2002-05-01
影响因子：
5.3
通讯作者：
Hager, GL
中科院分区：
文献类型：
--
作者：
Fletcher, TM;Xiao, NQ;Hager, GL
糖皮质激素受体（GR）的染色质重塑与小鼠乳腺肿瘤病毒（MMTV）启动子的转录激活有关。我们重建了这个核蛋白转换与染色质组装在MMTV DNA。重塑事件是ATP依赖性的，并且需要来自HeLa细胞的核提取物或纯化的人Swi/Snf。通过使用直接相互作用测定（磁珠下拉），我们证明了GR将人Swi/Snf募集到MMTV染色质中。出乎意料的是，我们发现GR在重塑过程中从染色质模板中被主动置换。ATP依赖性GR位移逆转的三磷酸腺苷双磷酸酶的加入，是特定的染色质模板。分离反应也可以用纯化的人Swi/Snf诱导。虽然GR在Swi/Snf的染色质重塑过程中明显解离，但它参与了次级转录因子核因子1的结合。这些结果被最近的一项发现所证实，即在活细胞中，蛋白质占据的受体经历染色质和核质区室之间的快速交换。在体外和体内的结果是一致的动态模型（击中和运行），其中GR首先结合染色质后，配体活化，招募重塑活动，促进转录因子结合，并同时失去了从模板。
Chromatin remodeling by the glucocorticoid receptor (GR) is associated with activation of transcription at the mouse mammary tumor virus (MMTV) promoter. We reconstituted this nucleoprotein transition with chromatin assembled on MMTV DNA. The remodeling event was ATP dependent and required either a nuclear extract from HeLa cells or purified human Swi/Snf. Through the use of a direct interaction assay (magnetic bead pull-down), we demonstrated recruitment of human Swi/Snf to MMTV chromatin by GR. Unexpectedly, we found that GR is actively displaced from the chromatin template during the remodeling process. ATP-dependent GR displacement was reversed by the addition of apyrase and was specific to chromatin templates. The disengagement reaction could also be induced with purified human Swi/Snf. Although GR apparently dissociated during chromatin remodeling by Swi/Snf, it participated in binding of the secondary transcription factor, nuclear factor 1. These results are paralleled by a recent discovery that the hormone-occupied receptor undergoes rapid exchange between chromatin and the nucleoplasmic compartment in living cells. Both the in vitro and in vivo results are consistent with a dynamic model (hit and run) in which GR first binds to chromatin after ligand activation, recruits a remodeling activity, facilitates transcription factor binding, and is simultaneously lost from the template.