Wardell Suzanne E, Narayanan Ramesh, Weigel Nancy L, Edwards Dean P
Baylor College of Medicine, Department of Molecular and Cellular Biology, Houston, Texas 77030, USA.
Mol Endocrinol. 2010 Feb;24(2):335-45. doi: 10.1210/me.2008-0081. Epub 2009 Dec 11.
Jun dimerization protein-2 (JDP-2) is a progesterone receptor (PR) coregulatory protein that acts by inducing structure and transcriptional activity in the disordered amino-terminal domain (NTD) of PR. JDP-2 can also potentiate the partial agonist activity of the PR antagonist RU486 by mechanisms that have not been defined. Functional mutagenesis experiments revealed that a subregion of the NTD (amino acids 323-427) was required for the partial agonist activity of RU486 induced by PR interaction with JDP-2. However, this subregion was not required for JDP-2 enhancement of the activity of progestin agonists. Mutation of phosphorylation sites within this region of the NTD showed that phosphorylation of serine 400 was required for the partial agonist activity of RU486 stimulated by JDP-2, but was not required for activity of hormone agonist, either in the presence or absence of JDP-2. Cyclin-dependent kinase 2 (Cdk2)/cyclin A is a novel PR coregulator that binds the NTD and acts by phosphorylating steroid receptor coactivator-1 and modulating steroid receptor coactivator-1 interaction with PR. Cdk2/cyclin A also potentiated the partial agonist activity of RU486; however, phosphorylation of serine 400 was not required, indicating that JDP-2 and Cdk2/cyclin A act by distinct mechanisms. We conclude that PR bound to RU486 and associated with JDP-2 adopts an active conformation in a subregion of the NTD requiring phosphorylation of serine 400 that is distinct from that promoted by progestin agonists. These data underscore the structural flexibility of the NTD of PR, and the ability of steroid ligands together with interacting proteins to affect the conformation and activity of the NTD.
Jun二聚化蛋白2（JDP-2）是一种孕激素受体（PR）共调节蛋白，它通过诱导PR无序氨基末端结构域（NTD）的结构和转录活性发挥作用。JDP-2还可通过尚未明确的机制增强PR拮抗剂RU486的部分激动剂活性。功能诱变实验表明，PR与JDP-2相互作用诱导的RU486部分激动剂活性需要NTD的一个亚区域（氨基酸323-427）。然而，该亚区域对于JDP-2增强孕激素激动剂的活性并非必需。NTD该区域内磷酸化位点的突变表明，JDP-2刺激的RU486部分激动剂活性需要丝氨酸400的磷酸化，但无论有无JDP-2，激素激动剂的活性都不需要该磷酸化。细胞周期蛋白依赖性激酶2（Cdk2）/细胞周期蛋白A是一种新型PR共调节因子，它与NTD结合，通过磷酸化类固醇受体辅激活因子-1并调节类固醇受体辅激活因子-1与PR的相互作用发挥作用。Cdk2/细胞周期蛋白A也增强了RU486的部分激动剂活性；然而，不需要丝氨酸400的磷酸化，这表明JDP-2和Cdk2/细胞周期蛋白A通过不同的机制发挥作用。我们得出结论，与RU486结合并与JDP-2相关的PR在NTD的一个亚区域采用一种活性构象，该亚区域需要丝氨酸400的磷酸化，这与孕激素激动剂促进的构象不同。这些数据强调了PR的NTD的结构灵活性，以及类固醇配体与相互作用蛋白一起影响NTD构象和活性的能力。
