UNDERSTANDING THE FIDELITY OF MAP KINASE SIGNALING

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 丝裂原活化蛋白激酶(MAPK)信号转导通路在真核细胞中发挥着重要作用，参与了细胞的生长、分化和应激反应等多种生物学过程。在酵母中，交配、丝状化和高渗透压甘油(HOG)途径对不同的刺激产生特定的反应，但共享多种成分。 我们观察到交配和丝化途径的MEK和MAPK在通过HOG途径的信号传递过程中都在其激活残基上被磷酸化。因此，必须在MAPK下游存在机制，以确保交配和丝状化基因不会在渗透胁迫下转录。此外，我们发现这是一种新的机制，不同于用于防止丝化和交配路径之间的串扰的机制。 我们测试了在交配和丝化特异性转录因子STE12和Tec1被招募到它们的基因靶标之前或之后是否实现了特异性，发现在没有Hog1的情况下，Tec1与丝化特异性启动子的结合水平有很大的增加。这表明，Hog1通过阻止Tec1与其目标启动子结合，在抑制错误信号方面发挥了重要作用。这些结果表明，真核细胞使用新的调控模式来执行维持信号特异性这一不可或缺的功能。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Mitogen-activated protein kinase (MAPK) signaling cascades play a fundamental role in eukaryotic cells, acting as signal transducers involved in many biological processes including growth, differentiation and response to stress. In yeast, the mating, filamentation, and high osmolarity glycerol (HOG) pathways elicit specific responses to distinct stimuli, yet share multiple components. We observed that both the MEK and the MAPKs of the mating and filamentation pathways are phosphorylated on their activating residues during signaling through the HOG pathway. Therefore, mechanisms must exist downstream of the MAPKs to ensure that mating and filamentation genes are not transcribed in response to osmotic stress. In addition, we found that this is a novel mechanism, distinct from the mechanisms used to prevent cross-talk between the filamentation and mating pathways. We tested whether specificity is achieved before or after the mating and filamentation specific transcription factors, Ste12 and Tec1, are recruited to their gene targets, and found that in the absence of Hog1 there is a large increase in the levels of Tec1 binding to filamentation specific promoters. This indicates that Hog1 plays an essential role in inhibiting erroneous signaling by preventing Tec1 from binding to its target promoters. These results point to new modes of regulation used by eukaryotic cells to perform the indispensable function of maintaining signaling specificity.