MAP kinase cascade signal transmission and specificity

描述（由申请方提供）：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节，包括细胞生长、分裂、分化和死亡的正常和病理学方面。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异性偶联的问题。级联反应中的激酶如何区分正确的底物和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？这种竞争性的更新建议提出的实验，解决MAP激酶和它们的底物和监管机构之间的识别的特异性，并调查的机制，限制不适当的信号交叉（或“泄漏”）之间的不同途径共享组件。我们继续研究酵母和哺乳动物MAPK途径，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。具体目的是（1）阐明MAPK对接位点的选择性MAPK激酶的D位点（2）评估MEK D-位点功能和体内特异性;（3）通过预测JNK-对接位点鉴定JNK MAP激酶的新底物和调节剂;（4）确定酵母中特异性的Fus 3 MAPK依赖性反馈控制的分子机制;（5）研究酵母Ste 5支架蛋白如何有助于信号传导特异性;（6）询问MAPK Kss 1和Fus 3是否具有不同的靶位点偏好。慢性激活，对反馈控制的敏感性丧失和特异性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）如何找到它们的靶点，提高我们预测底物和调节剂的能力，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.