G PROTEIN-MEDIATED NUTRITIONAL SIGNALING IN YEAST

酵母中 G 蛋白介导的营养信号传导

• 批准号: 6030324
• 负责人: Jeanne P. Hirsch
• 金额: $ 23.79万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-01 至 2003-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6030324
• 关键词: G protein; biological signal transduction; cell growth regulation; fungal genetics; growth media; guanine nucleotide binding protein; guanosine triphosphate; microorganism growth; nutrient requirement; nutrition related tag; pheromone; plant physiology; receptor binding; receptor coupling; yeasts

Cell growth is regulated by signal transduction pathways that respond to extracellular stimuli. In yeast, the signal that promotes growth is thought to be the availability of nutrients. Nutritional signaling involves the activation of Ras proteins and adenylyl cyclase through a process that is not well understood. Results presented in this proposal demonstrate that nutritional signaling in yeast also involves the activation of a G protein alpha-subunit by a G protein-coupled receptor. Several observations suggest that this pathway is activated in response to nitrogen starvation. For example, strains lacking the receptor or the G protein are defective for pseudohyphal growth, a developmental switch that is induced by nitrogen starvation. The long-term objective of this project is a description of the mechanisms employed by the G protein-mediated pathway to signal in response to nutritional conditions. Classical genetics and protein biochemistry will be used to elucidate the roles of genes and their encoded proteins in this process. The aims of this project are to characterize and identify the ligand for a newly described G protein-coupled receptor and to determine when the receptor is physiologically active. The first specific aim will investigate the conditions under which the Gpr1p receptor is bound to its ligand. These studies will be performed by coupling the Gpr1p receptor to the pheromone response pathway and using a well-established reporter construct that detects activation of the pathway. The second specific aim will employ the Gpr1p reporter system to characterize and identify the Gpr1p ligand. Identification of such a ligand would be one of the first examples of a receptor-binding molecule that activates a nutritional signaling pathway in a eukaryotic organism. The final specific aim will characterize the regulation of Gpr1p receptor expression and stability. Investigation of this novel signaling system will contribute to an understanding of nutritional signaling in eukaryotes, an area in which many important questions have not yet been addressed. Significant progress in elucidating signal transduction mechanisms has been made in organisms in which sophisticated genetic manipulations can easily be performed. A complete understanding of growth control in yeast is likely to provide insight into growth control in mammals, which is also regulated by signaling through G proteins and Ras. Such information is essential for understanding the process of carcinogenesis, in which cells escape this regulation and exhibit uncontrolled growth.

细胞生长受响应细胞外刺激的信号转导通路的调节。在酵母中，促进生长的信号被认为是营养的可获得性。营养信号涉及RAS蛋白和腺苷环化酶的激活，这一过程还不是很清楚。这项研究的结果表明，酵母中的营养信号还涉及G蛋白偶联受体激活G蛋白α亚单位。一些观察表明，这一途径是在氮饥饿反应中被激活的。例如，缺乏受体或G蛋白的菌株在假菌丝生长方面存在缺陷，这是一种由氮饥饿诱导的发育开关。这个项目的长期目标是描述G蛋白介导的信号通路对营养条件做出反应的机制。经典遗传学和蛋白质生物化学将被用来阐明基因及其编码的蛋白质在这一过程中的作用。该项目的目的是表征和鉴定一种新描述的G蛋白偶联受体的配体，并确定该受体何时具有生理活性。第一个特定目标将调查Gpr1p受体与其配体结合的条件。这些研究将通过将Gpr1p受体与信息素反应途径偶联，并使用公认的检测该途径激活的报告结构来进行。第二个具体目标将利用Gpr1p报告系统来表征和鉴定Gpr1p配体。这种配体的鉴定将是激活真核生物中营养信号通路的受体结合分子的第一个例子之一。最终的特定目标将表征Gpr1p受体表达的调节和稳定性。对这种新的信号系统的研究将有助于理解真核生物中的营养信号，这是一个许多重要问题尚未解决的领域。在阐明信号转导机制方面已经取得了重大进展，在生物体中可以很容易地进行复杂的遗传操作。对酵母生长控制的全面了解可能有助于深入了解哺乳动物的生长控制，而哺乳动物的生长控制也受G蛋白和RAS信号的调控。这些信息对于理解癌变过程是必不可少的，在癌变过程中，细胞逃避这一调控，表现出不受控制的生长。