Protein 14-3-3σ interacts with and favors cytoplasmic subcellular localization of the glucocorticoid receptor, acting as a negative regulator of the glucocorticoid signaling pathway
Protein 14-3-3σ interacts with and favors cytoplasmic subcellular localization of the glucocorticoid receptor, acting as a negative regulator of the glucocorticoid signaling pathway
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DOI：
10.1074/jbc.m302818200
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发表时间：
2003-07-11
影响因子：
4.8
通讯作者：
Chrousos, GP
中科院分区：
文献类型：
--
作者：
Kino, T;Souvatzoglou, E;Chrousos, GP
糖皮质激素受体（GR）α与高度保守的14-3-3家族蛋白相互作用。后者结合“伴侣”分子的磷酸化丝氨酸/苏氨酸残基，并通过改变它们的亚细胞定位和/或保护它们免受蛋白水解而影响许多信号转导事件。为了研究14-3-3对糖皮质激素信号通路的生理作用，我们研究了GR α在充满或缺乏14-3-3sigma的细胞系中的核质穿梭和反式激活特性。我们发现，内源性14-3- 3 σ有助于本地化绿色荧光蛋白融合GR α在细胞质中的配体的情况下，并加强其核输出后，配体撤出。14-3-3 sigma还抑制GR α在糖皮质激素应答启动子上的转录活性。14-3-3sigma的经典核输出信号的破坏使其影响GR α的核质运输和反式激活活性的能力失活，而引入突变使14-3-3sigma与其一些伴侣蛋白的结合活性失活则没有。14-3-3σ通过其COOH-末端部分以部分配体依赖的方式结合GR α的配体结合结构域，而它根本不与GR β的“配体结合结构域”相互作用。这些结果表明，14-3-3sigma在糖皮质激素信号通路中起负调节剂的作用，可能是通过其核输出信号将该受体的亚细胞定位/循环向细胞质转移。由于14-3-3蛋白在许多细胞活动中发挥重要作用，如细胞周期进程、生长、分化和凋亡，这些作用可能间接影响GR α的转录活性。相反，通过其14-3-3蛋白质相互作用，GR α可能会影响这些过程。
The glucocorticoid receptor (GR) alpha interacts with the highly conserved 14-3-3 family proteins. The latter bind phosphorylated serine/threonine residues of "partner" molecules and influence many signal transduction events by altering their subcellular localization and/or protecting them from proteolysis. To examine the physiologic role of 14-3-3 on the glucocorticoid-signaling pathway, we studied the nucleocytoplasmic shuttling and transactivation properties of GRalpha in a cell line replete with or devoid of 14-3-3sigma. We found that endogenous 14-3-3sigma helped localize green fluorescent protein-fused GRalpha in the cytoplasm in the absence of ligand and potentiated its nuclear export after ligand withdrawal. 14-3-3sigma also suppressed the transcriptional activity of GRalpha on a glucocorticoid-responsive promoter. Disruption of the classic nuclear export signal of 14-3-3sigma inactivated its ability to influence the nucleocytoplasmic trafficking and transactivation activity of GRalpha, whereas introduction of a mutation inactivating the binding activity of 14-3-3sigma to some of its partner proteins did not. 14-3-3sigma bound the ligand-binding domain of GRalpha through its COOH-terminal portion, in a partially ligand-dependent fashion, while it did not interact with "ligand-binding domain" of GRbeta at all. These results suggest that 14-3-3sigma functions as a negative regulator in the glucocorticoid signaling pathway, possibly by shifting the subcellular localization/circulation of this receptor toward the cytoplasm through its nuclear export signal. Since 14-3-3 proteins play significant roles in numerous cellular activities, such as cell cycle progression, growth, differentiation, and apoptosis, these actions might indirectly influence the transcriptional activity of GRalpha. Conversely, through its 14-3-3 protein interactions, GRalpha may influence these processes.