Mutation of histidine 874 in the androgen receptor ligand-binding domain leads to promiscuous ligand activation and altered p160 coactivator interactions
Mutation of histidine 874 in the androgen receptor ligand-binding domain leads to promiscuous ligand activation and altered p160 coactivator interactions
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DOI：
10.1210/me.2005-0231
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发表时间：
2005-12-01
影响因子：
--
通讯作者：
McEwan, IJ
中科院分区：
文献类型：
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作者：
Duff, J;McEwan, IJ
雄激素受体（AR）信号通路是前列腺癌治疗的主要靶点。在同源激素配体睾酮和二氢睾酮（DHT）存在的情况下，AR作为配体激活的转录因子发挥作用。我们在配体结合结构域（LBD）的螺旋10/11 c末端发现了一个高度保守的序列，该序列在前列腺癌中容易发生受体点突变。该序列包括苏氨酸877，它与类固醇分子D环的氢键有关，当突变为丙氨酸或丝氨酸时，会导致AR的混杂配体激活。该区域的第二个突变H874Y也产生了一个受体蛋白，该受体蛋白具有更宽的配体结合特异性，但与野生型受体相似，保留了对DHT的亲和力（K-d = 0.77 nM）。在大肠杆菌中表达的突变型AR-LBD的结构与野生型AR-LBD相比，在DHT存在时没有显著改变，但在没有激素的情况下，对蛋白酶消化的敏感性略有增加。该突变体AR表现出野生型AR- lbd / n末端结构域相互作用，但与p160共激活蛋白家族的所有三个成员的结合和转激活活性显著增强。总之，这些表型变化可能赋予肿瘤细胞在激素治疗导致的低雄激素环境中的选择性优势。
The androgen receptor (AR) signaling pathway is a major therapeutic target in the treatment of prostate cancer. The AR functions as a ligand-activated transcription factor in the presence of the cognate hormone ligands testosterone and dihydrotestosterone (DHT). We have characterized a highly conserved sequence at the C-terminal end of helix 10/11 in the ligand-binding domain (LBD), which is prone to receptor point mutations in prostate cancer. This sequence includes threonine 877 that is involved in hydrogen bonding to the D ring of the steroid molecule and leads to promiscuous ligand activation of the AR when mutated to alanine or serine. A second mutation in this region, H874Y, also results in a receptor protein that has broadened ligand-binding specificity, but retains an affinity for DHT (K-d = 0.77 nM) similar to that of the wild-type receptor. The structure of the mutant LBD, expressed in Escherichia coli, is not dramatically altered compared with the wild-type AR-LBD in the presence of DHT, but shows a modestly increased sensitivity to protease digestion in the absence of hormone. This mutant AR showed wildtype AR-LBD/N-terminal domain interactions, but significantly enhanced binding and transactivation activity with all three members of the p160 family of coactivator proteins. Together, these phenotypic changes are likely to confer a selective advantage for tumor cells in a low androgen environment resulting from hormone therapy.