Deubiquitination regulation of c-Myc

c-Myc 的去泛素化调控

基本信息

批准号：
9245658
负责人：
Mu-Shui Dai
金额：
$ 37.65万
依托单位：
OREGON HEALTH & SCIENCE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-04-01 至 2020-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9245658
关键词：
Affect Binding Biochemical Biogenesis Biology Burkitt Lymphoma Cell Culture Techniques Cell Nucleolus Cell Proliferation Cells Complex Cultured Cells DNA Polymerase II DNA Polymerase III Deubiquitinating Enzyme Deubiquitination Event Family member Gene Targeting Genes Genetic Transcription Goals Growth Homeostasis Hot Spot Human In Vitro Investigation Lead Link MCF10A cells MYC Box Malignant Neoplasms Mammary Tumorigenesis Mediating Messenger RNA Molecular Mus Mutation Normal Cell Nucleoplasm Oncogenic Oncoproteins Phosphorylation Play Post-Translational Protein Processing Proteins Proteolysis Proto-Oncogene Proteins c-myc Recombinant DNA Recruitment Activity Regulation Reporting Research Ribosomes Role Serine Serum Signal Transduction Stress System Testing Threonine Translations Ubiquitin Ubiquitination base c-myc Genes cancer therapy cell growth feeding high throughput screening in vivo insight killings knock-down malignant breast neoplasm mammary epithelium mouse model multicatalytic endopeptidase complex mutant novel novel therapeutics overexpression promoter protein degradation public health relevance response small molecule inhibitor therapeutic development therapeutic target tumor xenograft tumorigenesis ubiquitin ligase ubiquitin-protein ligase ubiquitin-specific protease

项目摘要

DESCRIPTION (provided by applicant): The c-Myc oncoprotein is essential for normal cell growth and proliferation. However, overexpression of c-Myc occurs in most human cancers. Thus, its level and activity must be tightly regulated during normal cell homeostasis. The ubiquitination-proteasome system plays a key role in controlling c-Myc levels and activity. c-Myc normally undergoes rapid ubiquitin-dependent proteolysis, but it is transiently stabilized by key phosphorylation events in response to growth signals. Phosphorylation of Serine 62 (S62) stabilizes c-Myc, whereas phosphorylation of Threonine 58 (T58) promotes c-Myc ubiquitination by the SCFFbw7 ubiquitin ligase and proteasomal degradation, mainly in the nucleolus. Like other post-translational modifications, ubiquitination can be reversed by the action of deubiquitinating enzymes (DUBs). While several ubiquitin ligases have been identified for c-Myc, only one DUB, USP28, has been reported to target c-Myc. We have recently discovered that the nucleolar deubiquitinating enzyme USP36 is a novel c-Myc regulator. USP36 binds to c-Myc and deubiquitinates c-Myc in cells and in vitro. Overexpression of wild-type USP36, but not its catalytic-inactive C131A mutant, stabilizes c-Myc and enhances c-Myc-driven transcription. Knockdown of USP36 reduces c-Myc levels and drastically suppresses cell proliferation. Importantly, USP36 interacts with the nucleolar Fbw7γ and abolishes Fbw7γ-mediated c-Myc degradation. In contrast, USP28 antagonizes Fbw7-mediated c-Myc degradation. Since the bulk of c-Myc is degraded in the nucleolus, our discovery leads to the novel hypothesis that USP36 functions as a crucial regulator of c-Myc by deubiquitinating c-Myc in the nucleolus. Interestingly, we found that USP36 itself is a c-Myc target gene, suggesting that USP36 and c-Myc form a positive feed-forward regulatory loop. To gain further insight into the role of USP36 in the regulation of c-Myc protein stability, activity and oncogenicity, we will investigate the molecular and biochemical mechanisms underlying the regulation of c-Myc by USP36 in Aim 1, including how USP36 interplays with Fbw7γ to regulate c-Myc in the nucleolus, whether it interplays with USP28 in the dynamic control of c-Myc ubiquitination, and the importance of c-Myc-USP36 feed-forward regulation. We will elucidate the functional consequences of USP36 regulation of c-Myc in cells in Aim 2 by analyzing whether USP36 regulates c-Myc binding and turnover at target gene promoters, whether it promotes c-Myc-dependent ribosome biogenesis, and whether it promotes c-Myc's oncogenic potential in cells and in vivo. Finally, we will elucidate whether USP36 is a therapeutic target using cell based and mouse models as proposed in Aim 3, including the investigation of USP36 deregulation in human breast cancers, whether deletion of USP36 inhibits c-Myc-driven mammary tumorigenesis in mice, and high-throughput screening of small molecule inhibitors for USP36. Achieving these goals will provide critical insight into how c-Myc is properly regulated by dynamic ubiquitination and deubiquitination, how deregulation of this dynamic contributes to tumorigenesis, and how USP36 can be targeted in human cancers.

描述（由申请人提供）：在大多数人类癌症中，C -YC癌蛋白对于正常的细胞生长至关重要。控制C-YC水平和活性的关键作用。 -CFFFBW7泛素连接酶和蛋白酶的泛素化，主要是在其他翻译后修饰中，可以通过泛素化合物的作用来逆转泛素。 DUB已被rep28过度，核酸酶usp36是一种新型的C-myc usp36与C-YC结合，并在细胞中deuperligitine c-yc和c-myc。 YC驱动的usp36的转录降低了C- MYC水平，并抑制了细胞的序言，USP36与核仁FBW7γ相互作用，并取消了FBW7γ介导的YC降解。 YC在核仁中降解，我们的发现导致了一个新的假设，即USP36作为C-Myc的C-Myc的关键调节剂C-Myc，我们发现USP36本身是C-YC靶基因，这表明USP3666 C-MyC对USP36在C-YC蛋白质，活性和致癌性的调节中的作用形成了阳性的洞察力。 C-YC在AIM 1中由usp36，与fbw7γ的相互作用，与核酸c-yc泛素化中的常规c-myc，以及C-myc-usp36进料法调节的重要性。 AIM 2中细胞中的C-YC通过分析靶基因启动子的USP36周转，是否促进C-YC依赖性核糖体生物发生，以及它是否促进了C- MYC的c- myc的致癌潜力和体内。 A。 C-Myc I通过动态泛液和去泛素化，去泛素化，动态如何促进肿瘤发生以及如何靶向人类癌症中的USP36。