Regulation of polarized cell growth by GTPases

GTPases 对极化细胞生长的调节

• 批准号: 7015774
• 负责人: Hay-Oak Park
• 金额: $ 31.22万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7015774
• 关键词: Saccharomyces cerevisiae; actins; cell cycle; cell growth regulation; cellular polarity; cytoskeleton; enzyme activity; enzyme complex; fluorescence spectrometry; fungal genetics; gene expression; gene interaction; genetic regulation; guanosinetriphosphatase activating protein; guanosinetriphosphatases; hydrolysis; macromolecule; molecular assembly /self assembly; molecular genetics; protein structure function

DESCRIPTION (provided by applicant): Polarity establishment and oriented cell divisions are central to the development of many organisms. Cells of the budding yeast S. cerevisiae exhibit two distinct patterns of budding depending on their cell type, reflecting genetic programming of cell polarization. It is believed that a cell responds to a cell-type-specific cortical marker, which is associated with the plasma membrane. All cell types use a common downstream pathway for polarity establishment, which involves the Ras and Rho family GTPases Rsr1/Bud1 and Cdc42. Despite current knowledge of many proteins involved in budding, how polarity is established toward a spatially defined site is largely unknown. This proposal focuses on how a macromolecular complex that specifies a specific bud site is assembled, and how polarity establishment is controlled in a spatial and temporal manner. Based on genetic and biochemical data, it is hypothesized that GTPases regulate various steps of polarity establishment. To test the hypothesis, multi-directional approaches will be undertaken using molecular genetic, biochemical, and cell biological methods. Specific aims are to understand: 1) How a macromolecular complex that specifies a bud site is assembled and how the transient spatial information is inherited in every cell division cycle; 2) how Bud2 and Bud5, regulators for Rsr1, interact with a distinct spatial landmark in each cell type, and whether the interactions regulate their activity; and 3) how Rsr1 regulates Cdc24, a GEF for Cdc42, and assembly of the Cdc42 complex at the bud site. Although polarity establishment is a complex problem, the facile genetics of yeast provides the unique opportunity to study a signaling pathway leading to polarized organization of the actin cytoskeleton at the molecular level. Development of mammalian cells also requires continual changes in the actin cytoskeleton in response to internal and external signals as seen during wound healing or chemotaxis during infection. Understanding the molecular mechanism underlying polarity establishment in yeast is expected to provide the molecular basis of actin cytoskeleton organization in mammalian cells. Given the structural and functional conservation of GTPases and their regulators in eukaryotes, knowledge gained will also allow an insight into novel mechanisms for these critical regulators of normal development, which is expected to be relevant to most eukaryotes including humans.

描述（由申请人提供）：极性建立和定向细胞分裂对于许多生物的发展至关重要。酿酒酵母芽的细胞根据其细胞类型表现出两种不同的发芽模式，反映了细胞极化的遗传编程。据信，一个细胞对细胞型特异性皮质标记有反应，该标志物与质膜有关。所有细胞类型都使用公共下游途径用于极性建立，其中涉及RAS和RHO家族GTPases RSR1/BUD1和CDC42。尽管目前了解许多参与萌芽的蛋白质，但如何建立对空间定义位点的极性是未知的。该提案的重点是如何组装特定芽位的大分子复合物，以及如何以空间和时间方式控制极性建立。基于遗传和生化数据，假设GTPases调节了极性建立的各个步骤。为了检验假设，将使用分子遗传，生化和细胞生物学方法进行多方向方法。具体目的是了解：1）如何组装芽位点的大分子复合物以及如何在每个细胞分裂周期中遗传瞬态空间信息； 2）RSR1的调节剂Bud2和Bud5如何与每种细胞类型中的不同空间地标相互作用，以及相互作用是否调节其活性； 3）RSR1如何调节Cdc24（用于Cdc42的GEF）以及在芽位处的CDC42复合物的组装。尽管极性建立是一个复杂的问题，但酵母的便捷遗传学为研究信号传导途径提供了独特的机会，从而导致分子水平的肌动蛋白细胞骨架的极化组织。哺乳动物细胞的发育还需要响应内部和外部信号的肌动蛋白细胞骨架的持续变化，如伤口愈合或感染过程中趋化性时所见。了解酵母中极性建立的分子机制有望提供哺乳动物细胞中肌动蛋白细胞骨架组织的分子基础。鉴于GTPa​​ses及其在真核生物中的调节剂的结构和功能保护，获得的知识也将洞悉正常发育的这些关键调节剂的新机制，这有望与包括人类在内的大多数真核生物有关。