CK2-dependent phosphorylation of Progesterone Receptors mediates proliferative si

项目摘要 孕激素是一种对乳房发育至关重要的卵巢类固醇激素。孕激素受体（PR） 主要存在于两种共表达的同种型PR-A和PR-B中。对基因敲除小鼠的研究表明， PR-B是乳腺腺泡形成过程中增殖信号传导所必需的。相反，需要PR-A 用于子宫发育，其中孕酮抑制增殖。对监管了解甚少 PR组织和亚型特异性转录。同种型特异性促有丝分裂（乳腺PR-B）和 是否达到抑制/分化（子宫中的PR-A）效应？PR-A和PR-B最常共表达于 相同的组织和细胞只表达一种PR亚型是罕见的，除了乳腺癌， 正常的1：1比例经常改变。选择性PR亚型抑制（阻断PR-B的促增殖作用） 同时保留PR-A的保护或抗增殖作用）将代表在以下方面的重大进展： 乳腺癌预防和/或治疗。PR是高度事后修改的。磷酸化， 主要作用于PR-B N-末端丝氨酸残基，显著改变受体的稳定性、定位、转录 活性和启动子选择性。我们的初步数据表明，PR-B特异性增殖的基础， 在乳腺癌细胞中的作用涉及CK2依赖性PR-B Ser81的选择性磷酸化， 蛋白质相互作用结构域，共同对接（CD）结构域，只在PR-B中发现，而不是PR-A。 PR-B Ser81的磷酸化调节增殖和促存活基因的高度特异性子集， 包括已知调节乳腺干细胞区室的所选PR调节基因，例如 Wnt1和STAT5A。此外，我们的数据表明，STAT5A可能作为一个"先锋因子"， 募集/指导磷酸化Ser81-PR-B特异性基因调控的基因组结合配偶体。这个目标 研究计划是确定蛋白质如何通过CD结构域与PR-B相互作用， PR-B在Ser81上的磷酸化，从而决定PR-B亚型特异性的基因转录事件 对于乳腺癌细胞增殖、促存活和干细胞区室的扩增是重要的。 假设：PR和STAT 5共调节磷酸化PR-B靶基因的特定亚组（通过CD结构域）。 MKP 3和ck2的依赖性募集，随后是ck2介导的PR-B Ser81的磷酸化）， 调节乳腺癌细胞增殖和促存活，部分通过调节乳腺干细胞 所选基因在配体不存在的情况下由磷酸-PR-B调节。CK 2依赖 PR-B的活化可加速乳腺肿瘤的发展和/或驱动早期乳腺癌的进展。

Project Summary Progesterone is an ovarian steroid hormone essential for breast development. The progesterone receptor (PR) exists primarily in two co-expressed isoforms, PR-A and PR-B. Studies from knockout-mice have shown that PR-B is required for proliferative signaling during mammary gland alveologenesis. In contrast, PR-A is required for uterine development, where progesterone inhibits proliferation. Very little is understood regarding regulation of PR tissue- and isoform-specific transcription. How are isoform-specific mitogenic (PR-B in the breast) and inhibitory/differentiative (PR-A in the uterus) effects achieved? PR-A and PR-B are most often co-expressed in the same tissues, and cells that express only a single PR isoform are rare, except in breast cancer where the normal 1:1 ratio is frequently altered. Selective PR isoform inhibition (blocking pro-proliferative effects of PR-B while preserving the protective or anti-proliferative effects of PR-A) would represent significant progress in breast cancer prevention and/or treatment. PR is highly post-translationally modified. Phosphorylation, primarily on PR-B N-terminal serine residues, significantly alters receptor stability, localization, transcriptional activity and promoter selectivity. Our preliminary data suggest that the basis for PR-B-specific proliferative actions in breast cancer cells involves ck2-dependent selective phosphorylation of PR-B Ser81 via a unique protein interaction domain, the common docking (CD) domain, found exclusively in PR-B but not PR-A. Phosphorylation of PR-B Ser81 regulates a highly specific subset of proliferative and pro-survival genes, including selected PR-regulated genes known to modulate the mammary stem cell compartment, such as Wnt1 and STAT5A. Additionally, our data suggest that STAT5A may serve as a “pioneer factor”, an early genomic binding partner that recruits/directs phospho-Ser81-PR-B-specific gene regulation. The goal of this research proposal is to determine how proteins that interact with PR-B via the CD domain regulate direct phosphorylation of PR-B on Ser81, thereby dictating PR-B isoform-specific transcriptional events at genes important for breast cancer cell proliferation, pro-survival, and expansion of the stem cell compartment. Hypothesis: PR and STAT5 co-regulate a specific subset of phospho-PR-B target genes (through CD domain- dependent recruitment of MKP3 and ck2, followed by ck2-mediated phosphorylation of PR-B Ser81) that regulate breast cancer cell proliferation and pro-survival, in part via modulation of the mammary stem cell compartment; selected genes are regulated by phospho-PR-B in the absence of ligand. ck2-dependent activation of PR-B may accelerate mammary tumor development and/or drive early breast cancer progression.