Regulation of heterotrimeric G proteins by non-receptor activators

非受体激活剂对异源三聚体 G 蛋白的调节

基本信息

批准号：
9336939
负责人：
Gregory Gordon Tall
金额：
$ 32.51万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-01 至 2018-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9336939
关键词：
Affinity Alanine Alleles Aspartic Acid Attenuated Binding Binding Proteins Biochemical Biological Assay Biosynthetic Proteins Cell Extracts Cell-Free System Cells Client Complex Defect Disease Event Exhibits G-Protein-Coupled Receptors G-substrate GNAQ gene GTP Binding GTP-Binding Proteins Gene Deletion Genes Genetic Germ Glutaminase Goals Guanine Nucleotide Exchange Factors Guanine Nucleotides Guanosine Triphosphate Phosphohydrolases Heterotrimeric G Protein Subunit Heterotrimeric GTP-Binding Proteins Hormones Hyperactive behavior In Vitro Individual Insecta Kinetics Knock-out Knockout Mice Knowledge Learning Malignant Neoplasms Measures Mediating Methods Modeling Molecular Chaperones Molecular Conformation Mus Neurotransmitters Nucleotides Nude Mice Ocular Melanoma Oncogenes Oncogenic Oryctolagus cuniculus Pharmaceutical Preparations Phosphorylation Phosphorylation Site Physiological Production Protein Biosynthesis Proteins Refractory Regulation Reticulocytes Signal Transduction Site Specificity System Techniques Testing Therapeutic Tissues Titrations Translations Tube Tumorigenicity Wheat Work actionable mutation activation-induced cytidine deaminase base experimental study high throughput screening inhibitor/antagonist melanocyte melanoma mimetics mutant new therapeutic target promoter protein folding protein function protein protein interaction public health relevance small molecule inhibitor small molecule libraries stem tumorigenic

项目摘要

DESCRIPTION (provided by applicant): Ric-8A and Ric-8B are positive regulators of heterotrimeric G protein a subunit function. We have recently defined the cellular action of Ric-8 proteins towards Ga subunits. Ric-8 proteins act as molecular chaperones of nucleotide-free Ga conformations during biosynthetic Ga protein folding. In cells in which Ric-8 genes are deleted, cellular abundances of subsets of Ga subunits were reduced by 95%. Ric-8 proteins also exhibit in vitro guanine nucleotide exchange stimulatory activity towards Ga subunits, and we now believe this to be an in vitro phenomenon stemming from the capacity of Ric-8 to induce a partially folded Ga state that has reduced affinity for GDP. We will develop our hypothesis that Ric-8 proteins are Ga subunit molecular chaperones and investigate the mechanisms by which Ric-8 proteins work with other cellular chaperones including the TRiC/CCT (Chaperonin) complex and HSC70/90 systems to fold individual Ga subunits. We have preliminary evidence that there are complex rules and unique chaperone requirements of individual Ga subunits. We will then test a hypothesis that mouse tissue-specific Ric-8A gene deletion can genetically suppress oncogenic G protein or overactive GPCR-driven cancers. Two mouse melanoma models will be used in which GNAQ/11-Q209L (constitutively-active) alleles are the oncogenic driver mutations of metastatic ocular melanoma, and ectopic mGluR5 expression from a melanocyte promoter elicited robust melanoma. We hypothesize that melanocyte mGluR5 inappropriately activates Gq/11 to promote melanoma. Upon proof-of-concept that Ric-8 deletion will suppress the actions of these oncogenes by reducing Gaq/11 cellular abundances, we will perform screens to identify small molecule inhibitors of Ric-8 and G protein interactions. Our goal is to develop Ric-8 inhibitors as a means to indirectly block G protein disease signaling by reducing the abundance of (mutant) Ga subunits folded by Ric-8. Ric-8 inhibitors may prove efficacious against oncogenic G protein diseases and/or as augmentation therapies for existing GPCR therapeutics. We will also conduct a small project to investigate Ric-8A regulation by phosphorylation events and 14-3-3 binding to Ric-8A.

描述（由申请人提供）：RIC-8A和RIC-8B是异三聚体G蛋白A亚基函数的阳性调节剂。我们最近定义了RIC-8蛋白对GA亚基的细胞作用。 RIC-8蛋白在生物合成GA蛋白折叠过程中充当无核苷酸GA构象的分子伴侣。在删除RIC-8基因的细胞中，GA亚基子集的细胞丰度降低了95％。 RIC-8蛋白还表现出体外的鸟嘌呤核苷酸交换刺激活性对GA亚基，现在我们认为这是RIC-8的能力诱导诱导GDP亲和力的部分折叠GA状态的体外现象。我们将提出假设，即RIC-8蛋白是GA亚基分子伴侣蛋白，并研究RIC-8蛋白与其他细胞伴侣（包括Tric/CCT（伴侣蛋白）复合物）和HSC70/90系统的机制，以折叠单个Ga ununits。我们有初步证据表明，单个GA亚基有复杂的规则和独特的伴侣要求。然后，我们将检验一个假设，即小鼠组织特异性的RIC-8A基因缺失可以在遗传上抑制致癌G蛋白或过度活跃的GPCR驱动的癌症。将使用两个小鼠黑色素模型，其中GNAQ/11-Q209L（组成型活性）等位基因是转移性眼部黑色素瘤的致癌驱动突变，以及来自黑素细胞启动子引起的强稳健黑色素瘤的异位MGLUR5表达。我们假设黑素细胞MGLUR5不适当地激活GQ/11以促进黑色素瘤。概念证明RIC-8缺失将通过减少GAQ/11细胞丰度来抑制这些癌基因的作用，我们将执行筛选以鉴定RIC-8和G蛋白相互作用的小分子抑制剂。我们的目标是开发RIC-8抑制剂，作为通过减少RIC-8折叠的（突变）GA亚基的丰度来间接阻断G蛋白质疾病信号的一种手段。 RIC-8抑制剂可能证明对肿瘤G蛋白疾病和/或作为现有GPCR疗法的增强疗法有效。我们还将进行一个小型项目，以研究RIC-8A通过磷酸化事件调节，并与RIC-8A结合14-3-3。