Signal Mediated Growth Control by Osmotic Stress

本项目的重点是酵母的两个突变系，酿酒酵母，它们对高渗胁迫有异常反应。这些突变体被称为HOG1和HOG4，因为它们在高渗透压甘油实验中改变了细胞周期反应。这些突变体中改变的基因类似于编码一组蛋白激酶的基因，这些蛋白激酶已知参与细胞生长和分裂过程中的信号事件。渗透休克后会发生HOG1蛋白的酪氨酸磷酸化，这表明渗透应激反应是由蛋白磷酸化的变化介导的。蛋白磷酸化变化似乎是暴露于高渗溶液后信号转导链的基础。实验计划旨在表征信号转导途径中涉及HOG1和HOG4蛋白的中间步骤，并分析这些突变体在高渗休克后细胞周期进程的变化。这个项目旨在研究细胞如何感知和响应渗透胁迫。酵母的高渗处理通常会导致细胞周期停滞，但在最近发现的两种突变体中，不会发生停滞。这些突变体中改变的基因为高渗应激反应中激活的信号转导链提供了线索。该项目将为酵母中渗透胁迫反应的信号转导途径提供重要信息，并为其他类型细胞中渗透胁迫激活的潜在调节级联提供线索。

This project is focused on two mutant lines of the yeast, Saccharomyces cerevisiae, that respond anomalously to hyperosmotic stress. The mutants are known as HOG1 and HOG4, because of their altered cell cycle response in a High Osmolarity Glycerol assay. The altered genes in these mutants resemble genes that encode a group of protein kinases known to be involved in signalling events during cell growth and division. Osmotic shock is followed by the tyrosine phosphorylation of the HOG1 protein and suggests that osmotic stress responses are mediated by changes in protein phosphorylation. Protein phosphorylation changes appear to underlie the signal transduction chain that follows exposure to hypertonic solutions. The experimental plan is directed toward the characterization of intermediate steps in the signal transduction pathway that involve the HOG1 and HOG4 proteins, and in an analysis of changes in cell cycle progression in these mutants after hypertonic shock. %%% This project is directed toward the study of how cells sense and respond to osmotic stress. Hyperosmotic treatment in yeast normally results in cell cycle arrest, but in two recently-discovered mutants, arrest does not occur. The altered genes in these mutants have provided clues to the signal transduction chain that is activated during the hyperosmotic stress response. This project will provide important information on the signal transduction pathway responsible for the osmotic stress response in yeast, and clues to the underlying regulatory cascades that are activated by osmotic stress in other kinds of cells.