Role of the serine-threonine kinase PAK1 in prolactin-dependent signaling

丝氨酸-苏氨酸激酶 PAK1 在催乳素依赖性信号传导中的作用

基本信息

批准号：
7277718
负责人：
MARIA DIAKONOVA
金额：
$ 17.48万
依托单位：
UNIVERSITY OF TOLEDO
依托单位国家：
美国
项目类别：
财政年份：
2006
资助国家：
美国
起止时间：
2006-06-01 至 2008-08-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): In normal mammary development, the hormone prolactin (PRL) is critical for alveolar proliferation and differentiation. Increasing evidence supports the involvement of PRL in breast cancer, the leading type of cancer in women and the second leading cause (after lung cancer) of cancer death among women. In 2002, 203,500 new cases of breast cancer were expected to be diagnosed, and 39,600 women were expected to die of the disease. The prolactin receptor (PRLR) is detected in 80% of human breast cancers, and is overexpressed in breast cancer cells. Normal and tumor mammary epithelial cells synthesize PRL and PRLR, thus the PRL could behave as an autocrine growth factor for human breast cancer cells. These results suggest the need for a more complete understanding of PRLR signaling to growth promoting, anti-apoptotic pathways. Tyrosine (Tyr) kinase JAK2 was identified as a PRLR-bound signaling molecule. Identification of the proteins recruited to the PRLR-JAK2 and dissection of the signaling pathways that are subsequently activated will ultimately provide a basis for understanding PRL action. Preliminary data demonstrate that the serine-threonine kinase PAK1 associates with and is Tyr phosphorylated by JAK2. Two-dimensional peptide mapping identified three Tyr(s) of PAK1 which are phosphorylated by JAK2. Tyr phosphorylation of PAK1 by JAK2 was also shown to protect cells from apoptosis. This grant proposes to examine the hypothesis that PAK1 is a substrate for JAK2 and that in response to PRL, PAK1 is activated by JAK2-dependent Tyr phosphorylation and enhances PRL-dependent cell survival. Aim1 will verify that PRL promotes Tyr phosphorylation of PAK1 in vivo. Aim2 will determine whether JAK2 phosphorylation of PAK1 alters PAK1 kinase activity and/or ability of PAK1 to bind PAK1 targets. In Aim3 the effect of JAK2 Tyr phosphorylation of PAK1 on PRL-dependent cell survival will be determined. Because both PAK1 and PRL have been implicated in breast cancer, the proposed studies may ultimately fill out the existing gap between upstream PRL-PRLR-JAK2 events and downstream PAK1-dependent functions in our understanding of the mechanism of human breast cancer. Tyr phosphorylation of PAK1 by JAK2 is likely to represent a novel molecular target in the search for the etiology and treatment of human breast cancer.

描述（由申请人提供）：在正常乳房发育中，催乳素激素（PRL）对于肺泡增殖和分化至关重要。越来越多的证据支持 PRL 与乳腺癌有关，乳腺癌是女性的主要癌症类型，也是女性癌症死亡的第二大原因（仅次于肺癌）。 2002年，预计将诊断出203,500例乳腺癌新病例，预计将有39,600名妇女死于该病。催乳素受体 (PRLR) 在 80% 的人类乳腺癌中检测到，并且在乳腺癌细胞中过度表达。正常和肿瘤乳腺上皮细胞合成PRL和PRLR，因此PRL可以作为人类乳腺癌细胞的自分泌生长因子。这些结果表明需要更全面地了解 PRLR 信号传导至生长促进、抗凋亡途径。酪氨酸 (Tyr) 激酶 JAK2 被鉴定为 PRLR 结合信号分子。鉴定招募到 PRLR-JAK2 的蛋白质并剖析随后激活的信号通路将最终为理解 PRL 作用提供基础。初步数据表明，丝氨酸-苏氨酸激酶 PAK1 与 JAK2 相关，并被 JAK2 磷酸化。二维肽图谱鉴定出 PAK1 的三个酪氨酸被 JAK2 磷酸化。 JAK2 对 PAK1 的 Tyr 磷酸化也被证明可以保护细胞免于凋亡。该资助计划检验以下假设：PAK1 是 JAK2 的底物，并且响应 PRL，PAK1 被 JAK2 依赖性 Tyr 磷酸化激活，并增强 PRL 依赖性细胞存活。 Aim1 将验证 PRL 在体内促进 PAK1 的 Tyr 磷酸化。 Aim2 将确定 PAK1 的 JAK2 磷酸化是否会改变 PAK1 激酶活性和/或 PAK1 结合 PAK1 靶标的能力。在 Aim3 中，将确定 PAK1 的 JAK2 Tyr 磷酸化对 PRL 依赖性细胞存活的影响。由于 PAK1 和 PRL 都与乳腺癌有关，因此拟议的研究可能最终填补上游 PRL-PRLR-JAK2 事件与下游 PAK1 依赖性功能之间现有的空白，以帮助我们了解人类乳腺癌的机制。 JAK2 对 PAK1 的 Tyr 磷酸化可能代表寻找人类乳腺癌病因和治疗的新分子靶点。