Regulation of Ras by Monoubiquitination

单泛素化对 Ras 的调节

• 批准号: 8669021
• 负责人: Sharon L Campbell
• 金额: $ 38.68万
• 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 2017-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8669021
• 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; Human; Hydrolysis; In Vitro; 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; public health relevance; 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基因包括人类癌症中最常见的突变致癌基因类别（33%）。它们的蛋白质对应物作为GDP-GTP调节的开关来调节控制细胞生长、分化和凋亡的信号网络。突变激活的Ras蛋白难以被GTP酶激活蛋白灭活，并且持续与GTP结合，导致慢性下游效应物激活和信号传导。尽管经过了三十年的努力，但没有直接靶向突变Ras蛋白的有效抑制剂成功地达到临床应用。因此，许多过去和当前正在进行的努力都采取了间接方法，这些方法遇到了失败或缺乏抗肿瘤功效。在此，我们研究了Ras激活的一种新机制，涉及通过遍在蛋白化进行翻译后修饰。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，单泛素化对内在Ras功能的直接影响是什么？其次，先前的研究表明，当在NIH 3 T3小鼠成纤维细胞中异位表达时，防止单泛素化损害了活化的K-Ras促进肿瘤异种移植物生长的能力。这种修饰对于人结肠直肠肿瘤细胞中的内源性突变型和正常K-Ras有多重要，其中对突变型K-Ras和正常K-Ras在细胞增殖中的功能具有经验证的成瘾性？我们将通过对单泛素化的Ras进行生物化学和结构研究以及对泛素化缺陷的K-Ras进行生物学研究来解决这些问题，以严格评估其作用 在野生型和突变型K-Ras生物活性、效应子信号传导和调节中。