A role of the amino-terminal (N) and carboxyl-terminal (C) interaction in binding of androgen receptor to chromatin
A role of the amino-terminal (N) and carboxyl-terminal (C) interaction in binding of androgen receptor to chromatin
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DOI：
10.1210/me.2005-0298
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发表时间：
2006-04-01
影响因子：
--
通讯作者：
Wong, JM
中科院分区：
文献类型：
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作者：
Li, JW;Fu, JJ;Wong, JM
已知AR的N-末端结构域与其C-末端配体结合区之间存在激素依赖性的相互作用，这种N/C相互作用可调节AR的转录活性。利用非洲爪哇卵母细胞作为模型系统来研究染色质的转录调控，我们发现了两个先前报道的N/C相互作用缺陷AR突变体，一个缺失(23)FQNLF(27)(AR Delta F)，另一个带有Gly 21 to Glu突变(ARG21E)，在激活组装成染色质的各种报告中的转录方面令人惊讶地不活跃。进一步的染色质免疫沉淀实验表明，这些突变体不能结合小鼠乳腺肿瘤病毒长末端重复序列和组装成染色质的前列腺特异性抗原增强子。这一缺陷是染色质所特有的，因为这两个突变体在体外都可以与一个共识的AR反应元件结合，并在瞬时转染中激活由小鼠乳腺肿瘤病毒-长端重复序列驱动的转录，与野生型AR一样有效。为了进一步证实这一新发现，我们建立了293个稳定表达AR或AR Delta F突变体的细胞系。利用这些细胞系，我们通过染色质免疫沉淀实验证实，AR而不是AR Delta F可以与内源性前列腺特异性抗原增强子结合。此外，我们发现AR Delta F突变体与染色质重塑因子SWI/SNF的ATPase亚单位BRG1的相互作用很差。综上所述，我们的研究揭示了AR N/C相互作用在AR染色质结合中的新作用，并提出了一个工作模型，即AR需要适当的N/C相互作用才能招募SWI/SNF复合体，进而重塑染色质，使AR与染色质中的AR反应元件结合。
The N-terminal domain of AR is known to engage a hormone-dependent interaction with its C-terminal ligand-binding domain, and this N/C interaction is known to modulate AR transcriptional activity. Using Xenopus oocytes as a model system to study transcriptional regulation in chromatin, we found that two previously reported N/C interaction-defective AR mutants, one with deletion of (23)FQNLF(27)(AR Delta F) and one with a Gly 21 to Glu mutation (ARG21E), were surprisingly inactive in activating transcription from various reporters assembled into chromatin. Further study using chromatin immunoprecipitation assay revealed that these mutants failed to bind both mouse mammary tumor virus-long terminal repeat and prostate-specific antigen enhancer assembled into chromatin. This defect is specific to chromatin because both mutants could bind to a consensus AR response element in vitro and activate transcription driven by mouse mammary tumor virus-long terminal repeat in transient transfection as effective as the wild-type AR. To further substantiate this novel finding, we established 293 cell lines that stably expressed either AR or AR Delta F mutant in an inducible manner. Using these cell lines, we confirmed by using chromatin immunoprecipitation assay that AR but not AR Delta F could bind to the endogenous prostate-specific antigen enhancer. Furthermore, we found that the AR Delta F mutant interacts poorly with Brg1, the ATPase subunit of the chromatin-remodeling factor SWI/SNF. Taken together, our study reveals a novel role of AR N/C interaction in control of AR chromatin binding and suggests a working model that the proper N/C interaction is required for AR to recruit SWI/SNF complex, which in turn remodels chromatin to allow AR to bind to AR response elements in chromatin.