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）：该提案的总体目标是更好地了解与RAS相关的Ral-GTPase家族的功能。 Rala和Ralb与各种细胞功能有关，包括控制囊泡分选，基因表达和细胞增殖。作为GTPases，RAL蛋白充当分子开关，以将细胞外信号传输到特定的细胞内信号传导级联反应。 RAL蛋白通过与一个RAL特异性鸟嘌呤核苷酸交换因子（RAL-GEF）的家族之一相互作用，达到细胞中的活性GTP结合态。一类RAL-GEF与GTP结合的RA结合并激活，并且越来越多的证据支持了这样一种观念，即升高的Ral-GEF/RAL信号传导有可能有助于人类的发生。该提案将试图揭示两个新确定的过程的基础机制，通过该过程，将RAL-GEF（RAL-GDS）受到调节。一个过程通过与PDK1蛋白激酶相互作用来积极调节RAL-GEF活性，而另一个过程通过蛋白激酶D介导的磷酸化来调节RAL-GEF活性。 活性GTP结合的RAL蛋白与一组下游“效应子”蛋白的活性结合并改变了细胞过程。该提案中的研究将扩大我们最近的发现，即通过增强膜蛋白通过其新近鉴定的效应子，外外外侧细胞的基底外侧表面增强膜蛋白向基底外侧表面的传递速率，通过其新近鉴定的外循环剂，可能通过异常依赖性机制来增强膜蛋白在上皮细胞的基底外侧表面的递送速度。因此，一组目标是定义这两个密切相关的RAL家族活动差异的生化基础。另一个目标是确定参与基底外侧膜输送的其他RALA“效应器”。我们还计划定义RALA与外囊肿或其他RAL效应子的结合如何促进MDCK上皮细胞中的膜递送。了解RAL在此过程中的功能如何很重要，因为膜蛋白的递送和极化会导致严重的疾病，包括囊性纤维化，I细胞疾病，家族性，多囊性肾脏疾病以及可能的癌症。 最后，人们越来越多地认识到，RAL-GEF通过独立于激活GTPases的能力的机制来促进GTPases的下游信号传导。因此，该提案的另一个目的是评估RAL-GEF结合蛋白的贡献，以贡献功能，以补充由RAL-GEF/RAL信号级联介导的细胞过程中活性RAL的功能。