YEAST PHEROMONE SIGNAL TRANSDUCTION

描述(由申请人提供)：细胞的功能和行为取决于对细胞外环境中信号的反应能力。在真核细胞中，对外界信号的反应通常始于细胞膜，然后通过控制细胞质和核事件(包括基因表达)的信号转导途径传播到整个细胞。由于不同隔室之间的这种信息传递，信号蛋白的亚细胞定位是其功能的一个重要方面。此外，细胞对给定信号的反应是否合适的决定也必须与有关细胞生理状态的其他信息结合起来。这项建议使用酿酒酵母的交配反应作为一个模型系统，利用分子遗传学和细胞生物学的方法来理解真核细胞的信号转导。酵母对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，包括从酵母到人类的各种信号系统中普遍存在的蛋白质，如PAK家族蛋白、异源三聚体G蛋白、MAP激酶级联和支架蛋白。这个项目的长期目标是从分子水平上了解信号是如何通过这一途径被启动和传播的，重点是支架蛋白的功能、亚细胞定位的作用以及信号和细胞周期之间的接口。其中一个目标是确定MAP激酶级联支架蛋白Ste5中不同的结构域如何调控不同途径激酶之间的信号传递，以及不同结构域如何相互作用和协调以控制定位和功能。另一个项目将探索信号蛋白如何限制在质膜上的离散区域，以及这如何影响信号传递的效率和动力学。该信号通路中的蛋白质在进入细胞周期过程中被特定形式的细胞周期蛋白-CDK激酶识别的机制也将在研究中。总体而言，这些研究将有助于我们对信号转导的总体理解，这与正常细胞和病变细胞决定分化或增殖的机制有关。

DESCRIPTION (provided by applicant): Cell function and behavior depends on the ability to respond to signals in the extracellular environment. In eukaryotic cells, response to external signals is commonly initiated at the plasma membrane and subsequently disseminated throughout the cell by signal transduction pathways, which control cytoplasmic and nuclear events including gene expression. Because of this transfer of information between different compartments, the subcellular localization of signaling proteins is an important aspect of their function. In addition, cellular decisions about whether it is appropriate to respond to a given signal must also be integrated with other information about the physiological status of the cell. This proposal uses the mating reaction of the yeast Saccharomyces cerevisiae as a model system for understanding eukaryotic signal transduction, using a molecular genetics and cell biological approach. Response to mating pheromones in yeast involves the dynamic assembly of plasma membrane-localized signaling complexes, which include proteins found ubiquitously in a variety of signaling systems from yeast to humans, such as a PAK-family kinase, a heterotrimeric G protein, a MAP kinase cascade, and a scaffold protein. The long-term objective of this project is to gain a molecular understanding of how signaling through this pathway is initiated and propagated, with an emphasis on the function of scaffold proteins, the role of subcellular localization, and the interface between signaling and the cell cycle. One goal will be to determine how distinct domains in the MAP kinase cascade scaffold protein, Ste5, regulate the transmission of signal between different pathway kinases, and how different domains interact and coordinate with each other in order to control localization and function. Another project will probe how signaling proteins become restricted to discrete regions at the plasma membrane, and how this impacts the efficiency and dynamics of signal transmission. Also under investigation will be the mechanism by which proteins in this signaling pathway are recognized by specific forms of the cyclin-Cdk kinase during entry into the cell cycle. Overall, these studies will contribute to our general understanding of signal transduction, with relevance to the mechanisms by which both normal and diseased cells make decisions regarding differentiation or proliferation.