PAK1-Nck regulates cyclin D1 promoter activity in response to prolactin.
PAK1-Nck regulates cyclin D1 promoter activity in response to prolactin.
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DOI：
10.1210/me.2011-0062
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发表时间：
2011-06
影响因子：
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通讯作者：
J. Tao;Peter O. Oladimeji;Leah C. Rider;M. Diakonova
中科院分区：
文献类型：
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作者：
J. Tao;Peter O. Oladimeji;Leah C. Rider;M. Diakonova
泌乳素（PRL）在正常乳腺发育中对肺泡增殖和分化至关重要，也与乳腺癌有关。PRL通过改变细胞周期蛋白D1的表达影响细胞的增殖和生长。PRL通过Janus kinase 2 (JAK2)/信号转导和转录激活因子介导Cyclin D1启动子的转录激活，直接调控Cyclin D1的表达。p21激活的丝氨酸-苏氨酸激酶（PAK）1也参与了cyclin D1基因表达的调控。我们之前已经证明JAK2直接磷酸化PAK1，并在这里扩展这些数据以证明PAK1激活周期蛋白D1启动子以响应PRL。我们发现PAK1 Tyr 153、201和285 （JAK2磷酸化位点；PAK1 Y3F）的突变使响应PRL的PAK1核易位和PRL诱导的cyclin D1启动子活性降低了55%。PAK1核定位信号的突变使prl诱导的cyclin D1启动子活性降低46%。缺乏功能性核定位信号的PAK1 Y3F突变体使prl诱导的cyclin D1活性降低68%，这表明存在另一种依赖PAK1的机制来激活cyclin D1启动子。我们发现连接蛋白Nck在细胞质中隔离PAK1， PAK1和Nck的共表达抑制prl诱导的PAK1对细胞周期蛋白D1启动子活性的放大作用（95%的抑制）。这种抑制被PAK1-Nck结合的破坏部分消除。我们提出了两种依赖PAK1的机制来激活周期蛋白D1启动子活性，以响应PRL：通过酪氨酸磷酸化PAK1的核易位和通过Nck-PAK1复合物的形成将PAK1隔离在细胞质中。
Prolactin (PRL) is critical for alveolar proliferation and differentiation in normal mammary development and is also implicated in breast cancer. PRL influences cell proliferation and growth by altering the expression of cyclin D1. Cyclin D1 expression is directly regulated by PRL through the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 5-mediated transcriptional activation of the cyclin D1 promoter. A p21-activated serine-threonine kinase (PAK)1 has also been implicated in the regulation of cyclin D1 gene expression. We have previously demonstrated that JAK2 directly phosphorylates PAK1 and extend these data here to demonstrate that PAK1 activates the cyclin D1 promoter in response to PRL. We show that mutation of PAK1 Tyr 153, 201, and 285 (sites of JAK2 phosphorylation; PAK1 Y3F) decreases both PAK1 nuclear translocation in response to PRL and PRL-induced cyclin D1 promoter activity by 55%. Mutation of the PAK1 nuclear localization signals decreases PRL-induced cyclin D1 promoter activity by 46%. A PAK1 Y3F mutant lacking functional nuclear localization signals decreases PRL-induced cyclin D1 activity by 68%, suggesting that there is another PAK1-dependent mechanism to activate the cyclin D1 promoter. We have found that adapter protein Nck sequesters PAK1 in the cytoplasm and that coexpression of both PAK1 and Nck inhibits the amplifying effect of PRL-induced PAK1 on cyclin D1 promoter activity (95% inhibition). This inhibition is partially abolished by disruption of PAK1-Nck binding. We propose two PAK1-dependent mechanisms to activate cyclin D1 promoter activity in response to PRL: via nuclear translocation of tyrosyl-phosphorylated PAK1 and via formation of a Nck-PAK1 complex that sequesters PAK1 in the cytoplasm.