Function of the Ras Related Ral Proteins

Ras 相关 Ral 蛋白的功能

• 批准号: 7850413
• 负责人: LARRY FEIG
• 金额: $ 14.82万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-15 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7850413
• 关键词: 1-Phosphatidylinositol 3-Kinase; Adaptor Signaling Protein; Affect; Amino Acids; Binding; Binding Proteins; Biochemical; Biological; Biological Process; Cell Polarity; Cell Proliferation; Cell membrane; Cell physiology; Cells; Collaborations; Complement; Complex; Coupled; Cystic Fibrosis; Data; Disease; Doctor of Philosophy; EGF gene; Epithelial Cells; Event; Family; Family member; GTP Binding; Gene Expression; Genetic Transcription; Goals; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate Phosphohydrolases; Human; I-Cell Disease; Laboratories; Lead; Maintenance; Malignant Neoplasms; Mediating; Membrane; Membrane Proteins; Molecular; N-terminal; Oncogenic; PDPK1 gene; PH Domain; Phospholipase D; Phosphorylation; Phosphotransferases; Polycystic Kidney Diseases; Process; Protein Binding; Protein Kinase; Proteins; Regulation; Role; Signal Transduction; Sorting - Cell Movement; Surface; Testing; Vesicle; base; basolateral membrane; extracellular; interest; novel; polarized cell; protein activation; protein function; protein kinase D; ral A GTP-Binding Protein; ral Guanine Nucleotide Exchange Factor; response; trafficking; tumorigenesis

DESCRIPTION (provided by applicant): The overall goal of this proposal is to gain a better understanding of the functions of the Ras related Ral- GTPase family. RalA and RalB have been implicated in diverse cell functions including the control of vesicle sorting, gene expression and cell proliferation. As GTPases, Ral proteins function as molecular switches to transmit extracellular signals to specific intracellular signaling cascades. Ral proteins reach the active GTP bound state in cells by interacting with one of a family of Ral-specific guanine nucleotide exchange factors (Ral-GEFs). One class of Ral-GEFs binds to and is activated by GTP-bound Ras, and a growing body of evidence supports the idea that elevated Ral-GEF/Ral signaling has the potential to contribute to human oncogenesis. This proposal will attempt to reveal the mechanisms underlying two newly identified processes by which the Ral-GEF, Ral-GDS, is regulated. One process positively regulates Ral-GEF activity through interaction with the PDK1 protein kinase, and the other negatively regulates Ral-GEF activity through protein kinase D-mediated phosphorylation. Active GTP-bound Ral proteins bind to and alter the activity of a set of downstream "effector" proteins to influence cellular processes. Studies in this proposal will expand upon our recent finding that RalA but not RalB functions in the maintenance of cellular polarity by enhancing the rate of delivery of membrane proteins to the basolateral surface of epithelial cells through its newly identified effector, the exocyst, and possibly through an exocyst-independent mechanism. Thus, one set of goals is to define the biochemical basis for the difference in activities of these two closely related Ral family members. Another goal is to identify the additional RalA "effector" that participates in basolateral membrane delivery. We also plan to define how RalA binding to the exocyst or other Ral effectors promotes membrane delivery in MDCK epithelial cells. Understanding how Ral functions in this process is important because faulty delivery and polarization of membrane proteins can lead to serious diseases including cystic fibrosis, I cell disease, familial, polycystic kidney disease and possibly cancer. Finally, there is a growing appreciation that Ral-GEFs contribute to downstream signaling from GTPases by mechanisms that are independent from their ability to activate GTPases. Therefore, another aim of this proposal is to evaluate the contribution of Ral-GEF binding proteins for their ability to contribute functions that complement those of active Ral in cell processes mediated by the Ral-GEF/Ral signaling cascade.

描述（由申请人提供）：本提案的总体目标是更好地了解Ras相关Ral-GTdR家族的功能。RalA和RalB参与多种细胞功能，包括控制囊泡分选、基因表达和细胞增殖。作为GTP酶，Ral蛋白作为分子开关将细胞外信号传递到特定的细胞内信号级联。Ral蛋白通过与Ral特异性鸟嘌呤核苷酸交换因子（Ral-GEF）家族中的一个相互作用而在细胞中达到活性GTP结合状态。一类Ral-GEFs与GTP结合的Ras结合并被其激活，越来越多的证据支持这样的观点，即Ral-GEF/Ral信号传导的升高有可能促进人类肿瘤的发生。本建议将试图揭示两个新确定的过程的机制，其中Ral-GEF，Ral-GDS，是监管。一个过程通过与PDK 1蛋白激酶相互作用正向调节Ral-GEF活性，另一个过程通过蛋白激酶D介导的磷酸化负向调节Ral-GEF活性。 活性GTP结合的Ral蛋白结合并改变一组下游“效应”蛋白的活性以影响细胞过程。在这项建议中的研究将扩大我们最近的发现，RalA，但不是RalB的功能，在维持细胞的极性，通过其新确定的效应器，外囊，并可能通过外囊独立的机制，提高膜蛋白的传递率上皮细胞的基底外侧表面。因此，一组目标是确定这两个密切相关的Ral家族成员的活性差异的生化基础。另一个目标是鉴定参与基底外侧膜递送的另外的RalA“效应物”。我们还计划确定RalA如何与外囊或其他Ral效应物结合，以促进MDCK上皮细胞中的膜递送。了解Ral在这一过程中的功能是很重要的，因为膜蛋白的错误传递和极化可能导致严重的疾病，包括囊性纤维化，I细胞疾病，家族性多囊肾疾病和可能的癌症。 最后，越来越多的人认识到，Ral-GEF通过独立于其激活GTP酶的能力的机制促进来自GTP酶的下游信号传导。因此，该提议的另一个目的是评估Ral-GEF结合蛋白的贡献，以评估它们在由Ral-GEF/Ral信号级联介导的细胞过程中贡献补充活性Ral的功能的能力。