PROTEIN KINASE NETWORKS AND SPORULATION IN S. CEREVISIAE

描述(申请人提供)：蛋白质的可逆磷酸化是所有真核生物中控制细胞周期进程和发育的主要调控机制。酵母菌的减数分裂和孢子形成(孢子形成)为研究蛋白激酶信号通路提供了一个出色的模型系统。与高等真核生物的发育程序类似，产孢子的诱导是由细胞类型和环境信号共同控制的。一旦启动，细胞类型特定基因的转录级联最终导致一个在遗传和生化上与起始细胞不同的细胞。蛋白激酶网络已经被发现，它控制着减数分裂发育的多个步骤。这个网络的一个中心组成部分是激活蛋白激酶Cak1。在孢子形成过程中，MAP同源物Smk1、CDK样激酶IME2和CDK CDC28的激活需要Cak1。CAK1、IME2和SMK1基因受孢子形成的转录级联调控。这个网络通过DNA结合和染色质修饰调节蛋白在多个自我加强的步骤中控制减数分裂的进展。该建议的目的是确定Cak1/IME2/Smk1蛋白激酶网络的新成分，阐明控制其活性的分子机制，并确定与减数分裂进程相关的信号靶标。该提案的具体目的是：1-阐明Cak1是如何激活Smk1的MAPK的。2-阐明IME2是如何被磷酸化调控的3-阐明调节中晚期产孢子特异基因表达的分子机制，4-利用基因抑制方法识别Smk1途径的负调控因子。这些研究将为蛋白激酶网络如何控制一般的发育程序，特别是减数分裂发育提供机械性的见解。

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.