Yeast Pheromone Signal Transduction

 描述(申请人提供)：细胞的功能和行为取决于对细胞外环境中的信号做出反应的能力，并就是否增殖做出适当的决定。在真核细胞中，对外界信号的反应通常是从细胞膜开始的，然后通过信号转导途径传播到整个细胞，信号转导途径控制细胞质和核事件，包括基因表达。此外，对给定信号的潜在响应还必须与有关细胞的生理状态的其他信息相结合，例如细胞分裂周期中的位置。细胞分裂的过程包括一系列经过精心策划的 涉及许多蛋白质功能的深刻变化的事件。这些事件必须经过精心策划，以确保它们以高保真的方式发生，并且它们必须与信号通路协调，以便细胞分裂机制能够对相关信号做出反应并抵消干扰信号。本研究以酿酒酵母的交配反应为模型系统，运用分子遗传学和细胞生物学的方法，对真核细胞的信号转导和细胞分裂进行了研究。酵母交配信息素的反应涉及到质膜定位的信号复合体的动态组装，其中包括从酵母到人类普遍存在的蛋白质，如异源三聚体G蛋白和MAP激酶级联。这个项目的长期目标是从分子上了解细胞中的蛋白激酶活性是如何被调节和利用来控制细胞分裂和对刺激的反应的。具体的项目强调亚细胞定位在信号通路激活中的作用，以及 细胞周期蛋白在激活细胞周期蛋白激酶中的作用。一个目标将是确定MAP激酶级联支架蛋白Ste5的质膜定位如何受到动态磷酸化的调节，而动态磷酸化可能由多个蛋白激酶控制。另一个项目将探索Ste5中膜结合结构域的亲和力是如何通过相互作用受到多个侧翼位置的磷酸化调控的。此外，还将研究特定的细胞周期蛋白如何识别细胞周期蛋白依赖激酶(CDK)的底物蛋白，以及这些特定的相互作用如何有助于控制细胞形态。总体而言，这些研究将有助于我们对信号机制和细胞分裂的总体理解，这与正常和病变细胞做出分化或增殖决定的机制相关。

 DESCRIPTION (provided by applicant): Cell function and behavior depends on the ability to respond to signals in the extracellular environment and make appropriate decisions about whether or not to proliferate. In eukaryotic cells, responses to external signals are commonly initiated at the plasma membrane and then disseminated throughout the cell by signal transduction pathways, which control both cytoplasmic and nuclear events including gene expression. In addition, the potential responses to a given signal must also be integrated with other information about the physiological status of the cell such as the position in the cell division cycle. The process of cell division involves a sequential series of carefully orchestrated events that involve profound alterations in the functions of numerous proteins. These events must be carefully orchestrated to ensure that they occur with high fidelity, and they must coordinate with signaling pathways so that the cell division machinery can respond to relevant signals and counteract interfering signals. This proposal uses the mating reaction of the yeast Saccharomyces cerevisiae as a model system for understanding both eukaryotic signal transduction and cell division, using a molecular genetics and cell biological approach. The response to yeast mating pheromones involves a dynamic assembly of plasma membrane-localized signaling complexes, which include proteins found ubiquitously from yeast to humans, such as a heterotrimeric G protein and a MAP kinase cascade. The long-term objective of this project is to gain a molecular understanding of how protein kinase activities in cells are regulated and harnessed to control cell division and responses to stimuli. The specific projects emphasize the role of subcellular localization in the activation of signaling kinases, and the role of cyclin proteins in the activation of cell cycle kinases. One goal will be to determine how the plasma membrane localization of the MAP kinase cascade scaffold protein, Ste5, is regulated by dynamic phosphorylation that may be controlled by more than one protein kinase. Another project will probe how the affinity of the membrane-binding domain in Ste5 is controlled by interaction is modulated by phosphorylation at multiple flanking positions. Also under investigation will be how specific cyclin proteins recognize substrate proteins of the cyclin dependent kinase (CDK), and how these specific interactions contribute to control of cell morphology. Overall, these studies will contribute to our general understanding of signaling mechanisms and cell division, with relevance to the mechanisms by which both normal and diseased cells make decisions regarding differentiation or proliferation.