Phosphorylation-dependent antagonism of sumoylation derepresses progesterone receptor action in breast cancer cells
Phosphorylation-dependent antagonism of sumoylation derepresses progesterone receptor action in breast cancer cells
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DOI：
10.1210/me.2007-0248
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发表时间：
2007-12-01
影响因子：
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通讯作者：
Lange, Carol A.
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文献类型：
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作者：
Daniel, Andrea R.;Faivre, Emily J.;Lange, Carol A.
孕激素受体(PR)调节乳腺发育过程中的增殖并促进乳腺癌的进展，部分是通过与多肽生长因子的协同作用实现的。我们以前已经确定PR Ser294是直接调节PR位置、活性和周转的关键位点，以响应磷酸化事件。在这里，我们试图更好地了解荷尔蒙串扰如何改变公关功能。我们证明，孕激素(R5020和RU486)诱导PR Lys388的快速(15分钟)SUMOM化；SUMOM化抑制选定的孕酮反应元件驱动的和内源性启动子上的PR转录活性，并延缓配体诱导的PR下调。与这一发现一致，我们表明稳定但弱活性的磷酸突变体S294A PR严重相加。相反，由PR Lys388(K388R)突变或Sentrin(SUMO)特异性蛋白水解酶过度表达所产生的脱苏糖化PR对低浓度的孕激素敏感。K388R和S294A突变(KRSA双突变PR)的组合可以挽救受损的磷酸突变(S294A)受体的转录和周转。值得注意的是，磷酸化事件拮抗PR-B，但不能拮抗PR-A相扑。用表皮生长因子或瞬时表达活化的丝裂原活化蛋白/ERK激酶或细胞周期依赖性蛋白激酶2处理细胞，可诱导PR-B Ser294的磷酸化，并阻断PR-B的总氧化，从而降低受体的活性；PR-A对这些事件具有抵抗力。对不同激素信号的可逆PR总合作用的调节为激素反应性的快速异构体特异性改变提供了机制。在蛋白激酶活性升高的背景下，例如在乳腺发育或乳腺癌进展期间，磷酸化的PR-B可能被低估，转录过度活跃，并且不稳定/无法检测到。
Progesterone receptors (PRs) mediate proliferation during breast development and contribute to breast cancer progression, in part by synergizing with peptide growth factors. We have previously identified PR Ser294 as a key site for direct regulation of PR location, activity, and turnover in response to phosphorylation events. Herein, we sought to better understand how hormonal cross talk alters PR function. We demonstrate that progestins (R5020 and RU486) induce rapid (15 min) sumoylation of PR Lys388; sumoylation represses PR transcriptional activity on selected progesterone response element-driven and endogenous promoters and retards ligand-induced PR down-regulation. Consistent with this finding, we show that stabilized but weakly active phospho-mutant S294A PRs are heavily sumoylated. Conversely, desumoylated PR, created by mutation of PR Lys388 (K388R) or by overexpression of sentrin (SUMO)-specific protease desumoylating enzymes, are hypersensitive to low progestin concentrations. Combination of K388R and S294A mutations (KRSA double-mutant PR) rescues both transcription and turnover of impaired phospho-mutant (S294A) receptors. Notably, phosphorylation events antagonize PR-B but not PR-A sumoylation. Treatment of cells with epidermal growth factor or transient expression of activated mitogen-activated protein/ERK kinase kinase or cyclindependent protein kinase 2 induces PR-B Ser294 phosphorylation and blocks PR-B sumoylation, thereby derepressing receptor activity; PR-A is resistant to these events. Modulation of reversible PR sumoylation in response to diverse hormonal signals provides a mechanism for rapid isoform-specific changes in hormone responsiveness. In the context of elevated protein kinase activities, such as during mammary gland development or breast cancer progression, phosphorylated PR-B may be undersumoylated, transcriptionally hyperactive, and unstable/undetectable.