Genetic and Molecular Analysis of Differentiation Mechanismsin Saccharomyces cerevisae

酿酒酵母分化机制的遗传和分子分析

• 批准号: 9604247
• 负责人: Alan Myers
• 金额: $ 31.5万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-07-15 至 2000-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9604247&HistoricalAwards=false
• 关键词: Genetic; Molecular; Analysis; Differentiation; Mechanismsin

Myers 9604247 This project seeks to characterize mechanisms that specifically regulate cellular form and function in response to environmental stimuli. The ascomycete Saccharomyces cerevisiae can switch between the yeast form (YF) and the pseudohyphal form (PH) in response to defined culture conditions. Cellular characteristics that are affected in this differentiation include cell shape, cell size, cell polarity, and cell division cycle mechanisms. This project has identified two protein kinases, Elm1p and CDC28, in which mutations cause cells to adopt pseudohyphal form characteristics in all growth conditions. Elimination of Elm1p function causes cells to adopt the pseudohyphal form constitutively, indicating that this protein inhibits development of pseudohyphal characteristics in inappropriate environments. One or more forms of the cyclin-dependent kinase complex (CDK) in which CDC28 is the catalytic subunit also regulates yeast- pseudohyphal differentiation. A specific amino acid substitution in CDC28 causes constitutive execution of most aspects of the pseudohyphal form. These data are consistent with the hypothesis that various signaling processes impinge on CDC28, which in response, is functionally modified in a specific way. Modified CDK activity then causes various aspects of the pseudohyphal growth form to occur. In this way CDK may function to integrate various input signals from the environment and control the decision of whether or not to execute a certain differentiation process. This project will address the following specific objectives: 1) Determination of whether CDK alteration is required for cells to attain the pseudohyphal form in response to either of two signaling regimes known to induce this differentiation process in wild type cells; 2) Characterization of the functional differences between CDK in yeast form- and pseudohyphal form cells; 3) Characterization of the interaction between Elm1p and the evolutionarily conserved protein kinase cascade coded for by SEL2, SWE1, and CDC28; 4) Characterization of additional proteins that function in this differentiation circuitry. Completion of this research will advance our knowledge of the basic mechanisms by which genetically identical cells convert between different functional forms, and the mechanisms by which cell division is controlled. Cells with identical genetic information can take a wide variety of shapes and execute many different functions. Because multicellular animals and plants develop from a single cell, specific mechanisms must exist that cause the various descendants of the progenitor cell to adopt the specific forms and functions that arise reproducibly in mature organisms. Fundamental understanding of how multicellular organisms arise requires an understanding of these mechanisms, however, little is understood currently about the ways in which cells are instructed to adopt a specific shape. This project uses a tractable experimental system in which cell shape changes reproducibly in response to an external signal. By discerning the molecular mechanism that control this programmed shape change, fundamental information regarding the processes by which multicellular organisms develop is likely to be obtained.

MYERS 9604247这个项目试图描述特定调节细胞形态和功能以响应环境刺激的机制。子囊菌酿酒酵母可以在酵母形态(YF)和假菌丝形态(PH)之间切换，以响应特定的培养条件。在这种分化中受到影响的细胞特征包括细胞形状、细胞大小、细胞极性和细胞分裂周期机制。该项目已经确定了两种蛋白激酶Elm1p和CDC28，其中突变会导致细胞在所有生长条件下采用假菌丝形式的特征。Elm1p功能的消除导致细胞结构性地采用伪菌丝形式，表明该蛋白在不适当的环境中抑制伪菌丝特征的发展。以CDC28为催化亚基的一种或多种形式的细胞周期蛋白依赖性激酶复合体(CDK)也调节酵母-假菌丝的分化。CDC28中特定的氨基酸替换导致伪菌丝形式的大部分方面的结构性执行。这些数据与各种信号过程影响CDC28的假设是一致的，CDC28作为回应，以特定的方式在功能上被修改。然后，修饰的CDK活性导致假菌丝生长形式的各个方面发生。通过这种方式，CDK可以集成来自环境的各种输入信号，并控制是否执行特定的区分过程的决定。本项目将致力于以下具体目标：1)确定细胞是否需要根据已知的两种诱导野生型细胞分化的信号机制之一获得假菌丝形式；2)鉴定酵母形式的CDK和伪菌丝形式细胞之间的功能差异；3)鉴定Elm1p与由SEL2、SWE1和CDC28编码的进化保守的蛋白激酶级联之间的相互作用；4)鉴定在这种分化通路中发挥作用的其他蛋白质。这项研究的完成将促进我们对遗传相同的细胞在不同功能形式之间转换的基本机制的了解，以及控制细胞分裂的机制。具有相同遗传信息的细胞可以采取各种各样的形状，并执行许多不同的功能。因为多细胞动植物是从单个细胞发育而来的，所以必须存在特定的机制，使祖先细胞的不同后代采用成熟生物体中可重复出现的特定形式和功能。对多细胞生物体如何产生的基本理解需要了解这些机制，然而，目前对细胞被指示采用特定形状的方式知之甚少。这个项目使用了一种易于处理的实验系统，在该系统中，细胞形状会随着外部信号的变化而重复变化。通过辨别控制这种程序性形状变化的分子机制，很可能获得关于多细胞生物体发育过程的基本信息。