Atypical MAP Kinase Signal Transduction

项目总结： MAPK是许多信号转导的调节成分 影响真核细胞生长、分化和运动的途径。相对的 人们对非典型MAPK的功能和调控知之甚少 哺乳动物中的MAPK15/Erk8)仅在具有细胞运动性的真核生物中发现。非典型 MAPK不被传统的MAPK激酶激活，而外部信号 触发激活是未知的，除了模式生物Dictyostelius的阿米巴 用于趋化运动和发育。我们发现Dictyostelius 非典型的MAPK，ERK2，对多种信号的趋化运动是必不可少的。在我们的 我们之前资助的研究还发现ERK2可以磷酸化特定的 GATA转录因子GTAC的残基导致该因子的易位 从细胞核到细胞质，对至少两个趋化信号做出反应 促进不同的细胞命运。我们还证明了ERK2的活性并不是 体内激活所需，表明非传统的MAPK激酶调节 非典型的MAPK，而不是自动磷酸化。拟议的研究将 研究ERK2是否通过差异性修饰促进不同的细胞命运 GTAC或通过调节其他转录因子。我们将使用标记为GFP的 GTAC绘制ERK2对接地点地图，并将这些地点与其他组的对接地点进行比较 MAPK。我们还将使用免疫共沉淀、质谱学和基因 分析鉴定信号通路中与ERK2相关并发挥作用的蛋白质 并确定直接调节ERK2激活的蛋白质。这个项目的成果是 期望确定非典型MAPK调节和功能的具体机制和 揭示非典型MAPK信号在趋化运动和细胞命运中的作用 可以指导其他生物体中MAPK研究的测定，如 哺乳动物。

Project Summary: MAP kinases (MAPKs) are regulatory components of many signal transduction pathways that impact eukaryotic cell growth, differentiation, and movement. Relatively little is known about the function and regulation of atypical MAPKs (represented by MAPK15/Erk8 in mammals) found only in eukaryotes that have cell motility. Atypical MAPKs are not activated by conventional MAPK kinases and the external signals that trigger activation are not known except in the amoeba Dictyostelium, a model organism for chemotactic movement and development. We have found that the Dictyostelium atypical MAPK, Erk2, is essential for chemotactic movement to multiple signals. In our previously funded research we also discovered that Erk2 phosphorylates specific residues of a GATA transcription factor, GtaC, resulting in the translocation of this factor from the nucleus to the cytoplasm in response to at least two chemotactic signals that promote different cell fates. We have also demonstrated that Erk2 kinase activity is not required for activation in vivo indicating that an unconventional MAPK kinase regulates atypical MAPKs rather than autophosphorylation. The proposed research will investigate if Erk2 promotes different cell fates through the differentially modification of GtaC or through the regulation of other transcription factors. We will use a GFP tagged GtaC to map Erk2 docking sites and compare these to docking sites of other groups of MAPKs. We will also use co-immunoprecipitations, mass spectrometry, and genetic analysis to identify proteins that associate and function with Erk2 in signaling pathways and identify proteins that directly regulate Erk2 activation. The results of this project are expected to identify specific mechanisms of atypical MAPK regulation and function and uncover roles for atypical MAPK signaling in chemotactic movement and cell fate determination that can guide the research of MAPKs in other organisms such as mammals.