Protein Kinase Signaling and Cell Cycle Control

描述(申请人提供)：我们实验室的长期目标是在分子细节上了解蛋白激酶信号通路与磷酸丝氨酸/苏氨酸结合域如何调控细胞增殖的多个方面，包括细胞周期进程和细胞对DNA损伤的反应。在本研究中，我们探讨了MAPKAP Kinase-2的功能，MAPKAP Kinase-2是一种由p38MAPK激活的应激反应蛋白激酶，作为S期和有丝分裂进程的关键调节因子，对环境和内源性类型的DNA损伤做出反应。我们采用广泛的生物化学和分子细胞生物学相结合的方法，探讨了化学物质和UV-C辐射诱导DNA损伤后MAPKAP Kinase-2激活的信号转导机制，并研究了MAPKAP Kinase-2如何与Chk1等其他检查点激酶一起在培养的细胞中控制遗传毒性应激后细胞周期的进展。我们继续发展一个有条件的MAPKAP Kinase-2基因敲除小鼠，以探索MAPKAP Kinase-2是否在肉瘤和肺癌的基因定义模型中以及在环境致癌物诱导的结直肠癌和皮肤癌模型中作为肿瘤抑制因子发挥作用。最后，我们探讨了MAPKAP Kinase-2的下调是否促进了化学故意诱导的DNA损伤(如化疗)后的细胞死亡。这些研究应该阐明来自p38MAPK-MAPKAP Kinase-2通路的信号是如何与来自专门的DNA损伤反应通路的信号相结合来调节细胞对遗传毒性应激的反应的。拟议的实验结果将揭示MAPKAP Kinase-2是否作为一种肿瘤抑制基因在暴露于环境因素后调节癌症风险，以及MAPKAP Kinase-2的特异性靶向是否具有治疗价值，使肿瘤对传统化疗的细胞毒效应敏感。

DESCRIPTION (provided by applicant): The long-term goal of our laboratory is to understand, in molecular detail, how protein kinase signaling pathways together with phosphoserine/threonine-binding domains regulate multiple aspects of cell proliferation, including cell cycle progression and the cellular response to DNA damage. In the present proposal, we explore the function of MAPKAP Kinase-2, a stress-responsive protein kinase activated by p38 MAPK, as a critical regulator of S-phase and mitotic progression in response to environmental and endogenous types of DNA damage. We use a combination of extensive biochemistry and molecular cell biology to explore the signal transduction mechanisms involved in MAPKAP Kinase-2 activation after DNA damage induced by chemicals and UV-C irradiation, and examine how MAPKAP Kinase-2 functions together with other checkpoint kinases such as Chk1, to control cell cycle progression after genotoxic stress in cells in culture. We go on to develop a conditional MAPKAP Kinase-2 knock-out mouse to explore whether MAPKAP Kinase-2 functions as a tumor suppressor in genetically defined models of sarcoma and lung cancer, and in environmental carcinogen-induced models of colorectal and skin cancer. Finally, we explore whether down-regulation of MAPKAP Kinase-2 facilitates cell death after intentional chemically-induced DNA damage such as chemotherapy. These studies should clarify how signals from the p38 MAPK-MAPKAP Kinase-2 pathway, a global stress-responsive network that is activated by a wide variety of toxic insults, integrate with those from dedicated DNA damage response pathways, to regulate the cellular response to genotoxic stress. The results of the proposed experiments should reveal whether MAPKAP Kinase-2 functions as a tumor suppressor gene that modulates the risk of cancer after exposure to environmental agents, and whether specific targeting of MAPKAP Kinase-2 would be of therapeutic value for sensitizing tumors to the cytotoxic effects of conventional chemotherapy.