Protein Kinase Signaling and Cell Cycle Control

描述（由申请人提供）：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如何与磷酸丝氨酸/苏氨酸结合结构域一起调节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。在本提案中，我们探讨的功能MAPKAP激酶-2，应激反应蛋白激酶激活p38 MAPK，作为一个关键的调节器的S期和有丝分裂的进展，在响应环境和内源性类型的DNA损伤。我们使用广泛的生物化学和分子细胞生物学相结合，探索化学品和UV-C辐射诱导的DNA损伤后MAPKAP激酶-2激活的信号转导机制，并研究MAPKAP激酶-2如何与其他检查点激酶如Chk 1一起发挥作用，以控制细胞培养中遗传毒性应激后的细胞周期进程。我们继续开发条件性MAPKAP激酶-2敲除小鼠，以探索MAPKAP激酶-2是否在遗传定义的肉瘤和肺癌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激酶-2的下调是否会促进有意化学诱导的DNA损伤（如化疗）后的细胞死亡。这些研究应该阐明来自p38 MAPK-MAPKAP激酶-2通路的信号如何与来自专用DNA损伤反应通路的信号整合，以调节细胞对遗传毒性应激的反应。拟议的实验结果应揭示MAPKAP激酶-2是否作为肿瘤抑制基因发挥作用，调节暴露于环境因子后的癌症风险，以及MAPKAP激酶-2的特异性靶向是否具有治疗价值，可使肿瘤对常规化疗的细胞毒性作用敏感。

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.