Analysis of a MAP kinase in Yeast that is Required for Spore Development

真核细胞中的大量信号转导依赖于保守的激酶级联，其激活称为有丝分裂原活化蛋白（MAP）激酶的酶家族。 MAP激酶是对环境变化的适应性反应、对有丝分裂原的增殖反应和对发育过程中发生的信号的分化反应所必需的。 SMKI，编码一种发育调节的MAP激酶，是酿酒酵母孢子形成所需的。 酵母中的孢子形成是研究发育过程的一个很好的模型系统。 与高等真核细胞的分化程序类似，诱导受细胞类型和环境信号的组合控制。 一旦启动，观察到孢子形成特异性基因的精确控制的瞬时表达模式，最终导致细胞（或孢子）在遗传和生物化学上与其前体不同。 分子和细胞学分析表明，早期孢子形成程序（包括减数分裂I和II）正常发生在纯合smk 1二倍体。 然而，显微镜和功能分析表明，smk1 asci执行孢子壁形态发生和随后的发育事件是有缺陷的。 已经分离出一系列条件性和部分功能性smk1等位基因，这些等位基因显示出各种不同的发育缺陷。 我们将描述不同smk1等位基因的发育和形态发生缺陷。 在选定的smk1遗传背景中使用剂量抑制方法的相应突变体Smk1途径的生化缺陷。 MAP激酶信号通路的高度进化保守性使得这项研究可能为这些信号通路在协调各种生物体发育过程中的作用提供基本见解。

Winter 9630656 A large amount of signal transduction in eukaryotic cells depends on conserved kinase cascades that activate a family of enzymes called mitogen activated protein (MAP) kinases. MAP kinases are required for adaptive responses to changes in the environment, proliferative responses to mitogens, and differentiative responses to signals that occur during development. SMKI, encodes a developmentally regulated MAP kinase that is required for sporulation in Saccharomyces cerevisiae. Sporulation in yeast represents an excellent model system with which to study developmental processes. Similar to differentiation programs in higher eukaryotic cells, induction is controlled by a combination of cell-type and environmental signals. Once initiated, a precisely controlled, transient expression pattern is observed for sporulation-specific genes that ultimately leads to a cell (or spore) that is both genetically and biochemically distinct from its precursor. Molecular and cytological analysis show that the early sporulation program (including meiosis I and II) occurs normally in homozygous smk1 diploids. However, both microscopic and functional assays show that smk1 asci are defective for executing spore wall morphogenesis and subsequent developmental events. A collection of conditional and partial-function smk1 alleles have already been isolated that display a variety of distinct developmental defects. We will characterize the developmental and morphogenetic defects of different smk1 alleles. The biochemical defects of the corresponding mutant Smk1 pathway using dosage suppression approaches in selected smk1 genetic backgrounds. The high degree of evolutionary conservation in MAP kinase signaling pathways make it likely that this study will provide fundamental insights into the role of these signaling pathways in coordinating developmental processes in a wide variety of organisms.