Analysis of MAP kinase cascades in S. cerevisiae

描述（由申请人提供）：细胞通常通过利用丝裂原活化蛋白（MAP）激酶级联来调节负责适当细胞反应的基因表达来响应环境线索。我提议进行的实验旨在促进对细胞如何感知环境压力的理解，激活适当的MAP激酶级联反应，然后在细胞做出反应后停用级联反应。氮饥饿通过MAP激酶级联诱导酿酒酵母假菌丝的形成，该级联与高细胞外渗透压触发的MAP激酶级联具有相同的成分。Herskowitz实验室的研究已经确定了Sho1p作为氮饥饿的潜在传感器，除了它作为渗透压传感器的既定作用。我将进行基因筛选，以确定参与感知低氮的其他蛋白质。此外，我将研究如何调节Sho1p信号以防止高渗透压甘油和假菌丝生长途径的组成性激活。最后，使用MAPK Hog1p的化学抑制版本与DNA微阵列相结合，我将确定在应激和非应激条件下由Hog1p调节的基因。

DESCRIPTION (provided by applicant): Cells often respond to environmental cues by utilizing mitogen-activated protein (MAP) kinase cascades to regulate the expression of genes responsible for the appropriate cellular response. The experiments that I am proposing to conduct seek to advance the understanding of how cells sense environmental stress, activate the appropriate MAP kinase cascade, and then deactivate the cascade once the cell has responded. Nitrogen starvation induces the formation of pseudohyphae in S. cerevisiae via a MAP kinase cascade that shares components with a MAP kinase cascade triggered by high extracellular osmolarity. Studies from the Herskowitz lab have identified Sho1p as a potential sensor for nitrogen starvation in addition to its established role as a sensor of osmolarity. I will carry out genetic screens to identify other proteins involved in sensing low nitrogen. In addition, I shall investigate how Sho1p signaling is regulated to prevent constitutive activation of the high osmolarity glycerol and pseudohyphal growth pathways. Finally, using chemically inhibitable versions of the MAPK Hog1p in conjunction with DNA microarrays, I will identify genes regulated by Hog1p during both stress and non-stress conditions.