The F-domain of estrogen receptor-alpha inhibits ligand induced receptor dimerization.
The F-domain of estrogen receptor-alpha inhibits ligand induced receptor dimerization.
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雌激素受体-α 的 F 结构域抑制配体诱导的受体二聚化。
DOI：
10.1016/j.mce.2008.08.001
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发表时间：
2008
影响因子：
4.1
通讯作者：
Khan,SohaibA
中科院分区：
文献类型：
--
作者：
Yang,Jun;Singleton,DavidW;Shaughnessy,ElizabethA;Khan,SohaibA
雌激素受体（ERα）羧基端F结构域的作用尚不确定，但有证据表明，在17β-雌二醇（E2）存在下，该区域可能对ER二聚化产生内部抑制作用。为了鉴定影响人ERα激活的C-末端残基，我们创建了一系列缺失并检查了E2诱导的受体二聚化和反式激活。使用酵母双杂交试验，在存在2 nM E2的情况下，与野生型（wt）ERα相比，F结构域（Δ 7 b）的最后24个C末端氨基酸的缺失导致二聚化增加5倍。这种二聚化的增加类似于当整个F结构域缺失时观察到的增加。突变体：突变体同二聚体形成的测量与突变体：wt相互作用相比产生类似的增加。有趣的是，C末端的点突变（mut 3）显示出与纳摩尔量E2存在下的Δ 7 b相当的二聚化增加。然而，在亚纳摩尔水平的E2下，mut 3的行为与wt ERα相似，而Δ 7 b在二聚化中保持显著增加。E2结合亲和力（Kd）常数的测定显示，野生型和F-结构域突变体只有边际差异，表明F-结构域直接影响二聚化。我们还观察到F结构域突变体与p160家族共激活因子SRC 1的相互作用增强。最后，雌激素反应性报告基因2XERE-LacZ和3XERE-Luc在酵母和哺乳动物细胞中的转录调控分别反映了F结构域突变体二聚化倾向的增加。总之，这些数据表明ERα的C-末端氨基酸对于减弱E2诱导的受体二聚化和转录活性至关重要。
The role of the carboxyl terminal F-domain of estrogen receptor (ERα) is uncertain, but evidence suggests that this region may impart internal restraint on ER dimerization in the presence of 17β-estradiol (E2). To identify the C-terminal residues affecting human ERα activation, we created a series of deletions and examined E2 induced receptor dimerization and transactivation. Deletion of the final 24 C-terminal amino acids of the F-domain (Δ7b) yielded a fivefold increase in dimerization, when compared to wild type (wt) ERα in the presence of 2nM E2, utilizing a yeast two-hybrid assay. This increase in dimerization is similar to that observed when the entire F-domain was deleted. Measurement of mutant:mutant homodimer formation yielded similar increases compared to mutant:wt interactions. Interestingly, a point mutation at the C-terminus (mut 3) showed increases in dimerization comparable to that of Δ7b in the presence of nanomolar amounts of E2. However, at sub-nanomolar levels of E2, mut 3 behaved similarly to wt ERα, whereas Δ7b maintained striking increases in dimerization. Determination of E2 binding affinity (Kd) constants revealed only marginal differences for wt and F-domain mutants, suggesting that the F-domain affects dimerization directly. We also observed enhanced interaction of F domain mutants with p160 family coactivator SRC1. Finally, transcriptional regulation of estrogen responsive reporters, 2XERE-LacZ and 3XERE-Luc in yeast and mammalian cells, respectively, reflected the increased propensity for dimerization by F domain mutants. Together, these data indicate that the C-terminal amino acids of ERα are critical for attenuation of E2 induced receptor dimerization and transcriptional activity.