Regulation of Ras by Monoubiquitination

单泛素化对 Ras 的调节

• 批准号: 8881223
• 负责人: Sharon L Campbell
• 金额: $ 38.32万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8881223
• 关键词: Address; Affect; Affinity; Apoptosis; Binding; Biochemical; Biological; Cell Differentiation process; Cell Proliferation; Cells; Chronic; Clinic; Colorectal Cancer; Colorectal Neoplasms; Data; Dependence; Drug Industry; Embryo; Failure; Fibroblasts; Future; GTP Binding; GTPase-Activating Proteins; Gene Expression; Goals; Growth; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate; HRAS gene; Health; Human; Hydrolysis; In Vitro; KRAS2 gene; Ligation; Light; Malignant Neoplasms; Modification; Molecular; Monoubiquitination; Mus; Mutate; Mutation; Normal Cell; Nucleotides; Oncogene Proteins; Oncogenes; Phosphotransferases; Physiological; Population; Post-Translational Protein Processing; Process; Property; Protein Family; Proteins; Ras Inhibitor; Receptor Protein-Tyrosine Kinases; Refractory; Regulation; Role; Sampling; Signal Transduction; Signaling Molecule; Ubiquitin; Ubiquitination; United States National Institutes of Health; addiction; cancer cell; cancer therapy; cell growth; clinical application; genetic regulatory protein; in vivo; inhibitor/antagonist; innovation; meetings; mutant; neoplastic cell; novel; prevent; protein function; ras Proteins; tumor; tumor xenograft; tumorigenesis; tumorigenic

DESCRIPTION (provided by applicant): RAS genes comprise the most commonly mutated class of oncogenes in human cancer (33%). Their protein counterparts function as GDP-GTP regulated switches to modulate signaling networks that control cell growth, differentiation and apoptosis. Mutationally activated Ras proteins are refractory to inactivation by GTPase activating proteins, and are persistently GTP- bound, leading to chronic downstream effectors activation and signaling. Despite three decades of intensive effort, no effective inhibitors that directly target mutant Ras proteins have successfully reached clinical application. Therefore, much of the past and current ongoing efforts have taken indirect approaches, which have met with failure or lack of anti-tumor efficacy. Herein, we investigate a novel mechanism of Ras activation involving posttranslational modification by ubiquitination. Recent findings that covalen modification of Ras by monoubiquitination may be key for its ability to drive human oncogenesis, suggest one possible direction for developing direct Ras inhibitors. To rigorously assess this possibility, two key issues need to be addressed. First, what are the direct consequences of monoubiquitination on intrinsic Ras function? Second, the previous study showed that preventing monoubiquitination impaired the ability of activated K-Ras to promote tumor xenograft growth when ectopically- expressed in NIH3T3 mouse fibroblasts. How important is this modification for endogenous mutant and normal K-Ras in human colorectal tumor cells with validated addiction to mutant K- Ras and normal K-Ras function in cell proliferation? We will address these issues, by performing biochemical and structural studies on monoubiquitinated Ras as well as biological studies with ubiquitination-deficient K-Ras to rigorously assess its role in wild type and mutant K-Ras biological activity, effectors signaling and regulation.

描述（由申请人提供）：RAS 基因包含人类癌症中最常见的突变类癌基因（33%）。它们的蛋白质对应物充当 GDP-GTP 调节开关，调节控制细胞生长、分化和凋亡的信号网络。突变激活的 Ras 蛋白难以被 GTP 酶激活蛋白失活，并且持续与 GTP 结合，导致慢性下游效应器激活和信号传导。尽管经过三十年的努力，仍然没有直接针对突变Ras蛋白的有效抑制剂成功地达到临床应用。因此，过去和当前正在进行的许多努力都采取了间接方法，但都失败或缺乏抗肿瘤功效。在此，我们研究了 Ras 激活的新机制，涉及泛素化翻译后修饰。最近的研究结果表明，通过单泛素化对 Ras 进行共价修饰可能是其驱动人类肿瘤发生能力的关键，这为开发直接 Ras 抑制剂提供了一个可能的方向。为了严格评估这种可能性，需要解决两个关键问题。首先，单泛素化对 Ras 内在功能的直接后果是什么？其次，先前的研究表明，当在 NIH3T3 小鼠成纤维细胞中异位表达时，防止单泛素化会损害激活的 K-Ras 促进肿瘤异种移植物生长的能力。这种修饰对于人结直肠肿瘤细胞中的内源突变体和正常 K-Ras 有多重要，并且已验证对突变体 K-Ras 和正常 K-Ras 在细胞增殖中的功能成瘾？我们将通过对单泛素化 Ras 进行生化和结构研究以及对泛素化缺陷 K-Ras 进行生物学研究来解决这些问题，以严格评估其作用 野生型和突变型 K-​​Ras 生物活性、效应信号传导和调节。