PROTEIN KINASE NETWORKS AND SPORULATION IN S. CEREVISIAE

描述（由申请人提供）：在所有真核生物中，蛋白质的可逆磷酸化是控制细胞周期进程和发育的主要调控机制。酵母的减数分裂和孢子形成为研究蛋白激酶信号通路提供了一个很好的模型系统。与高等真核生物的发育过程类似，产孢的诱导是由细胞类型和环境信号共同控制的。一旦启动，细胞类型特异性基因的转录级联最终导致细胞在遗传和生物化学上与起始细胞不同。一个蛋白激酶网络已被确定控制减数分裂发育的多个步骤。这个网络的核心组成部分是活化激酶Cak1。在孢子形成过程中，Cak1是MAP激酶同源物Smk1、CDK样激酶Ime2和CDK Cdc28的激活所必需的。CAK1， IME2和SMK1基因受到孢子形成转录级联的严格调控。该网络通过dna结合和染色质修饰调节蛋白控制减数分裂过程的多个自我强化步骤。本研究的目标是鉴定Cak1/Ime2/Smk1蛋白激酶网络的新组分，阐明控制其活性的分子机制，并鉴定将信号传导到减数分裂过程的靶标。该建议的具体目的是：1-阐明Cak1如何激活Smk1 MAP激酶。2-阐明Ime2是如何通过磷酸化调控的3-阐明调控中后期孢子形成特异性基因表达的分子机制，4-利用遗传抑制方法确定Smk1通路的负调控因子。这些研究将提供关于蛋白激酶网络如何控制发育程序的机制见解，特别是减数分裂发育。

DESCRIPTION (provided by applicant): The reversible phosphorylation of proteins is a major regulatory mechanism that controls cell cycle progression and development in all eukaryotic organisms. Meiosis and spore formation in yeast (sporulation) provides an outstanding model system to study protein kinase signaling pathways. Similar to developmental programs in higher eukaryotes, induction of sporulation is controlled by a combination of cell-type and environmental signals. Once initiated, a transcriptional cascade of cell-type specific genes ultimately leads to a cell that is genetically and biochemically distinct from the starting cell. A protein kinase network has been identified that controls multiple steps in meiotic development. A central component of this network is the activating kinase Cak1. During sporulation Cak1 is required for activation of the MAP kinase homolog Smk1, the CDK-like kinase Ime2, and the CDK Cdc28. The CAK1, IME2 and SMK1 genes are tightly regulated by the transcriptional cascade of sporulation. This network controls meiotic progression at multiple self-reinforcing steps through DNA-binding and chromatin-modifying regulatory proteins. The goal of this proposal is to identify new components of the Cak1/Ime2/Smk1 protein kinase network, to elucidate molecular mechanisms that control its activities, and to identify targets that couple signaling to meiotic progression. The specific aims of the proposal are: 1- Elucidate how Cak1 activates the Smk1 MAP kinase. 2- Elucidate how Ime2 is regulated by phosphorylation 3- Elucidate molecular mechanisms that regulate mid-late sporulation-specific gene expression, and 4- Identify negative regulators of the Smk1 pathway using genetic suppression approaches. These studies will provide mechanistic insights into how protein kinase networks control developmental programs in general and meiotic development in particular.