MAP kinase cascade signal transmission and specificity

说明书(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和医学重要过程的调节，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一个问题，即它们如何实现信号与细胞反应的特定耦合。级联中的激酶如何区分它们的正确底物和大量不正确的底物？此外，当不同的信号由相同的组件传输时，它们如何引起不同的响应？这一竞争性更新提案提供了一些实验，这些实验解决了MAP激酶及其底物和调节器之间识别的特异性，并研究了限制不同通路共享成分之间不适当的信号交叉(或“泄漏”)的机制。我们继续研究酵母和哺乳动物的MAPK途径，以创新地利用从这两个实验系统获得的见解的协同交叉受精。其具体目的是(1)描述MAPK激酶(MKK或MEK)中同源MAPK和非同源MAPK的MAPK对接位点(‘D-Site’)的选择性，并开发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对接位点来寻找JNK MAP激酶的新底物和调节因子；(4)确定酵母中依赖Fus3MAPK的反馈控制特异性的分子机制；(5)研究酵母Ste5支架蛋白如何促进信号特异性；(6)询问MAPKs Kss1和Fus3是否有不同的目标位点偏好。慢性激活、对反馈控制的敏感性丧失和特异性的丧失似乎是许多癌症中MAPK调节失调的重要方面，这项研究将增加我们对这些问题的理解。更广泛地说，这项研究可以更好地理解MAP激酶(和其他激酶)是如何找到他们的靶点的，并提高我们预测底物和调节因子的能力，并最终可能提出基于蛋白激酶相互作用调节的新的治疗方法。

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.