The Fbw7 ubiquitin ligase network: normal and neoplastic functions

Fbw7 泛素连接酶网络：正常和肿瘤功能

基本信息

批准号：
10639893
负责人：
Bruce E Clurman
金额：
$ 46.3万
依托单位：
FRED HUTCHINSON CANCER CENTER
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-06-01 至 2028-05-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10639893
关键词：
Ablation Apoptosis Area Binding CCNE1 gene Cancer Biology Cell Proliferation Cell physiology Cells Development Dimerization Engineering Exhibits Genetic Transcription Genomic approach Glycogen Synthase Kinase 3 Goals Heterozygote Human Knock-in Malignant Neoplasms Metabolism Missense Mutation Modeling Mus Mutation Normal Cell Oncogenic Oncoproteins Pathway interactions Phosphoric Monoester Hydrolases Phosphorylation Phosphorylation Site Phosphotransferases Physiological Proliferating Proteins Regulation Research Role Signal Pathway Signal Transduction Substrate Specificity Testing Tumor Suppressor Proteins Ubiquitination Work c-myc Genes cancer cell cancer therapy cell type cellular engineering dimer glycosylation neoplastic neoplastic cell notch protein novel novel therapeutic intervention protein degradation transcription factor treatment strategy tumor tumorigenesis ubiquitin ligase ubiquitin-protein ligase

项目摘要

This application focuses on Fbw7, an E3 ubiquitin ligase and tumor suppressor, and on its substrate c-Myc (hereafter, Myc), an oncogenic transcription factor widely implicated in human cancers. E3 ligases mark protein substrates for degradation through ubiquitin conjugation. Fbw7 recognizes a network of proteins with crucial roles in proliferation, differentiation, metabolism, and apoptosis. Fbw7 substrates include important oncoproteins (e.g., cyclin E, Notch, Myc, Jun) and thus Fbw7 mutations promote tumorigenesis by deregulating its oncogenic substrates. The Fbw7 pathway therefore has broad implications for cancer biology and for the development of new therapeutic strategies. We will address important and unresolved aspects of this pathway in two general areas. The first involves how phosphorylation and Fbw7 control Myc stability and activity, in both normal cells and in cancers. The second area will address new paradigms in the ways that Fbw7 recognizes substrates and how these interactions may underlie Fbw7 mutations in cancers. This proposal may thus impact many areas of research related to Myc and the Fbw7 pathway. Fbw7 binds substrates after they are phosphorylated within motifs termed degrons, that typically contain two phosphorylated residues that interact with Fbw7. The first two Aims are focused on Myc regulation by phosphorylation of a newly discovered Myc T244 degron that acts in concert with the canonical Myc T58 degron to bind Fbw7 dimers. Aim 1 will study how T244 degron phosphorylation is regulated in normal and tumor cells and whether hierarchical Myc T244 degron phosphorylation controls Myc stability, as well as how the T58 and T244 degrons are coordinately regulated by mitogenic and oncogenic signaling pathways. Aim 2 will study the functions of the T244 degron in normal cells and tumorigenesis and how it cooperates with the T58 degron. This will be accomplished through physiologic knockin models, in human cells and mice, to create engineered Myc mutations that ablate Myc degron phosphorylations. Aim 3 will study how Fbw7 dimers interact with substrates and how these interactions underlie Fbw7 mutations and their functions in cancers. This includes determining the extent to which two separate degrons are required for degradation across the Fbw7 substrate network. Identifying these new degrons may lead to entirely new pathways that control the degradation of critical substrates and that may be abnormal in cancer cells. Tumors often have heterozygous Fbw7 missense mutations that dimerize with wt-Fbw7, and the hypothesis that these mutations specifically stabilize oncogenic substrates that require two degrons will be tested. Finally, the Myc T244 degron binds Fbw7 through a novel mode that involves Fbw7 R689, a tumor hotspot, and the role of R689 in dimer-dependent selective substrate recognition will be studied, as well as similar possible functions for other Fbw7 missense mutations.

该应用的重点是FBW7，E3泛素连接酶和肿瘤抑制剂，以及其底物C-MYC （以下简称MYC），一种广泛与人类癌症有关的致癌转录因子。 E3连接酶标记蛋白质底物通过泛素结合降解。 FBW7识别具有的蛋白质网络在增殖，分化，代谢和凋亡中的关键作用。 FBW7底物包括重要癌蛋白（例如Cyclin E，Notch，Myc，Jun），因此FBW7突变促进了肿瘤的发生放大其致癌底物。因此，FBW7途径对癌症具有广泛的影响生物学和开发新的治疗策略。我们将解决重要且尚未解决的问题这条途径在两个一般领域的各个方面。首先涉及磷酸化和FBW7如何控制MYC 正常细胞和癌症中的稳定性和活性。第二个区域将解决新的范式 FBW7识别底物的方式以及这些相互作用如何构成FBW7突变的基础癌症。因此，该建议可能会影响与MYC和FBW7途径有关的许多研究领域。 FBW7在称为Degrons的基序中磷酸化后结合底物，通常包含两个与FBW7相互作用的磷酸化残基。前两个目的专注于MYC调节新发现的Myc T244 Degron的磷酸化，该Degron与规范MYC T58合作 DEGRON结合FBW7二聚体。 AIM 1将研究如何在正常和肿瘤细胞以及分层MYC T244 DEGRON磷酸化是否控制MYC稳定性，以及 T58和T244 DEGRON如何通过有丝分裂和致癌信号通路协调调节。 AIM 2将研究正常细胞和肿瘤发生中T244 DEGRON的功能以及它如何合作与T58 Degron。这将通过生理敲击素模型，人类细胞和小鼠，创建工程化的MYC突变，以消融MYC DEGRON磷酸化。 AIM 3将研究如何 FBW7二聚体与底物相互作用，以及这些相互作用如何构成FBW7突变及其的基础癌症的功能。这包括确定需要两个单独的degron的程度 FBW7基板网络跨越降解。识别这些新的DEGRON可能会导致全新控制临界底物降解并且在癌细胞中可能异常的途径。肿瘤通常具有与WT-FBW7二聚体的杂合FBW7错义突变，并假设这些突变特异性稳定了需要两个DEGRON的致癌底物。最后，MYC T244 DEGRON通过涉及FBW7 R689的新模式结合FBW7，肿瘤热点， R689在二聚体依赖性选择性底物识别中的作用以及类似其他FBW7错义突变的可能功能。