Enhancement of cell surface expression and receptor functions of membrane progestin receptor α (mPRα) by progesterone receptor membrane component 1 (PGRMC1): evidence for a role of PGRMC1 as an adaptor protein for steroid receptors.
Enhancement of cell surface expression and receptor functions of membrane progestin receptor α (mPRα) by progesterone receptor membrane component 1 (PGRMC1): evidence for a role of PGRMC1 as an adaptor protein for steroid receptors.
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DOI：
10.1210/en.2013-1991
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发表时间：
2014-01
期刊：
影响因子：
4.8
通讯作者：
P. Thomas;Y. Pang;Jing Dong
中科院分区：
文献类型：
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作者：
P. Thomas;Y. Pang;Jing Dong
孕酮受体膜组分1（PGRMC 1）具有多种功能，包括作为膜孕酮受体的组分和作为接头蛋白。在这里，我们发现，在核孕酮受体（PR）阴性乳腺癌细胞系中稳定过表达人PGRMC 1，导致细胞膜上PGRMC 1和膜孕酮受体α（mPRα）表达增加，这与特异性[（3）H]孕酮结合增加有关。膜结合蛋白的亲和力和特异性是mPRα的特征，Kd为4.7 nM，对mPR特异性激动剂CANOD 02-0具有高亲和力，对皮质类固醇具有低亲和力。孕激素处理引起G蛋白的活化，进一步证明PGRMC 1转染的细胞膜上功能性mPR表达增加。免疫细胞化学和免疫共沉淀研究表明，PGRMC 1与细胞膜上的mPRα密切相关。将PGRMC 1转染到自发永生化的大鼠颗粒细胞中与PGRMC 1和mPRα的膜表达以及孕激素的抗凋亡作用相关，这些作用在与mPRα的小干扰RNA共转染后被取消。这些数据表明，PGRMC 1可以作为衔接蛋白，将mPRα转运到细胞表面，并且先前归因于PGRMC 1的β蛋白结合和凋亡功能依赖于mPRα的细胞表面表达。总的来说，结果表明PGRMC 1和mPRα是膜孕酮受体蛋白复合物的组分。在PGRMC 1转染的细胞膜中也观察到雌激素受体β的表达增加，表明PGRMC 1可以作为多种类固醇受体的衔接蛋白。
A variety of functions have been proposed for progesterone receptor membrane component 1 (PGRMC1), including acting as a component of a membrane progestin receptor and as an adaptor protein. Here we show that stable overexpression of human PGRMC1 in nuclear progesterone receptor (PR)-negative breast cancer cell lines causes increased expression of PGRMC1 and membrane progesterone receptor α (mPRα) on cell membranes that is associated with increased specific [(3)H]progesterone binding. The membrane progestin binding affinity and specificity were characteristic of mPRα, with a Kd of 4.7 nM and high affinity for the mPR-specific agonist, Org OD 02-0, and low affinity for corticosteroids. Progestin treatment caused activation of G proteins, further evidence for increased expression of functional mPRs on PGRMC1-transfected cell membranes. Immunocytochemical and coimmunoprecipitation studies showed a close association of PGRMC1 with mPRα in cell membranes. Transfection of PGRMC1 into spontaneously immortalized rat granulosa cells was associated with membrane expression of PGRMC1 and mPRα as well as antiapoptotic effects of progestins that were abolished after cotransfection with small interfering RNA for mPRα. These data demonstrate that PGRMC1 can act as an adaptor protein, transporting mPRα to the cell surface, and that the progestin binding and apoptotic functions previously ascribed to PGRMC1 are dependent on cell surface expression of mPRα. Collectively, the results suggest PGRMC1 and mPRα are components of a membrane progesterone receptor protein complex. Increased expression of estrogen receptor β was also observed in the membranes of PGRMC1-transfected cells, suggesting that PGRMC1 can act as an adaptor protein for multiple classes of steroid receptors.