MAP kinase cascade signal transmission and specificity

描述（由申请人提供）：丝裂原活化蛋白激酶（MAPK）信号通路参与许多生物学和医学重要过程的调控，包括细胞生长、分裂、分化和死亡的正常和病理方面。它们的普遍性和多功能性提出了它们如何实现信号与细胞反应的特定耦合的问题。级联中的激酶如何区分它们的正确底物与大量过量的错误底物？此外，当不同的信号由相同的组件传输时，它们是如何引起不同的反应的？这一竞争性更新提议提出的实验解决了MAP激酶及其底物和调节因子之间识别的特异性，并研究了限制不同通路共享组分之间不适当的信号交叉（或“泄漏”）的机制。我们将继续研究酵母和哺乳动物的MAPK通路，以创新地利用从这两个实验系统中获得的见解的协同交叉受精。具体目标是：(1)描述MAPK激酶（mkk或mek）中MAPK对接位点（“d位点”）对其同源与非同源MAPK的选择性，并建立一个模型来解释这些关系；(2)评估MEK d位点在体内的功能和特异性；(3)通过预测JNK对接位点，鉴定新的JNK MAP激酶底物和调控因子；(4)确定酵母中fus3mapk依赖性反馈调控特异性的分子机制；(5)研究酵母Ste5支架蛋白在信号特异性中的作用；(6)了解MAPKs Kss1和Fus3是否具有不同的靶点偏好。慢性激活、反馈控制敏感性的丧失和特异性的丧失似乎是许多癌症中MAPK失调的重要方面，这项研究将增加我们对这些问题的理解。更一般地说，这项研究可以更好地理解MAP激酶（和其他激酶）如何找到它们的靶标，提高我们预测底物和调节因子的能力，并可能最终提出基于蛋白激酶相互作用调节的新治疗方法。

DESCRIPTION (provided by applicant): Mitogen-activated protein kinase (MAPK) signaling pathways participate in the regulation of many biologically and medically important processes, including normal and pathological aspects of cell growth, division, differentiation, and death. Their ubiquity and versatility raise the issue of how they achieve specific coupling of signal to cellular response. How do the kinases in the cascade distinguish their correct substrates from the vast excess of incorrect substrates? Furthermore, how do different signals elicit distinct responses when they are transmitted by the same components? This competitive renewal proposal presents experiments that address the specificity of recognition between MAP kinases and their substrates and regulators, and that investigate the mechanisms that restrict inappropriate signal crossover (or 'leaking') between distinct pathways sharing components. We continue to investigate both yeast and mammalian MAPK pathways, in order to innovatively exploit the synergistic cross-fertilization of insights gained from these two experimental systems. Specific Aims are (1) to delineate the selectivity of MAPK-docking sites ('D-sites') in MAPK kinases (MKKs, or MEKs) for their cognate vs. non-cognate MAPKs and to develop a model to explain these relationships; (2) to assess MEK D-site function and specificity in vivo; (3) to identify new substrates and regulators of the JNK MAP kinase by predicting JNK-docking sites; (4) to determine the molecular mechanism of Fus3MAPK-dependent feedback control of specificity in yeast; (5) to investigate how the yeast Ste5 scaffold protein contributes to signaling specificity; (6) to ask if the MAPKs Kss1 and Fus3 have distinct target site preferences. Chronic activation, loss of sensitivity to feedback controls and loss of specificity appear to be important aspects of the MAPK dysregulation seen in many cancers, and this research will increase our understanding of these issues. More generally, this research could lead to a better understanding of how MAP kinases (and other kinases) find their targets and improve our ability to predict substrates and regulators and may ultimately suggest novel approaches to therapy based on the modulation of protein kinase interactions.