Regulation of the cell cycle by SCF and APC/C ubiquitin ligases

SCF 和 APC/C 泛素连接酶对细胞周期的调节

• 批准号: 7614302
• 负责人: MICHELE PAGANO
• 金额: $ 45.51万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7614302
• 关键词: Basic Science; Binding; Biochemical; Biological Assay; Biological Process; Boxing; Cancer Biology; Cell Cycle; Cell Cycle Progression; Cell Cycle Proteins; Cell Cycle Regulation; Cell Proliferation; Collection; Commit; Complex; Cyclin E; DNA biosynthesis; Dominant-Negative Mutation; Ensure; F-Box Proteins; Figs - dietary; Funding; Funding Agency; Human; Ligase; Malignant - descriptor; Mass Spectrum Analysis; Molecular; Protein Subunits; Proteins; Proteolysis; Recruitment Activity; Regulation; Rest; Role; SKP Cullin F-Box Protein Ligases; Schedule; Specificity; System; Time; Ubiquitin; Ubiquitin-Conjugating Enzymes; anaphase-promoting complex; base; beta-Transducin Repeat-Containing Proteins; cancer cell; multicatalytic endopeptidase complex; mutant; novel; protein complex; protein degradation; protein function; ubiquitin ligase

DESCRIPTION (provided by applicant): Temporally coordinated destruction of key cell cycle regulatory proteins by the ubiquitin-proteasome system represents an important regulatory mechanism to ensure that specific protein functions are turned off at the right time, in the right compartment and in a unidirectional fashion. Proteolysis of many core components of the cell cycle machinery is controlled by two major classes of ubiquitin ligases: the SCF (Skp1-Cul1-F-box protein) complexes and the Anaphase Promoting Complex/Cyclosome (APC/C). In humans there are sixty- eight SCF ligases, each characterized by a different F-box protein subunit that provides specificity by directly recruiting the substrate to the rest of the ligase and, ultimately, to the ubiquitin conjugating enzyme. Despite the large number of F-box proteins, only three human SCF ubiquitin ligases (containing the F-box proteins betaTrcp, Fbw7 and Skp2, respectively) have well-established substrates, many of which are involved in cell cycle control (e.g., Cdc25A, cyclin E, Emi1, p21, p27, Wee1). We propose a project focused on a new tier of control of the cell cycle networks and its integration with the ubiquitin system. Using a novel screen, we have identified six novel putative SCF substrates, and we will characterize the mechanism, regulation and biological function of the degradation of one of them, namely E2F3, a protein intimately involved in the control of the cell cycle (Aim 1). We will furthermore identify and characterize those biologically significant substrates that are targeted for destruction by the F-box protein Fbw5 to regulate cell cycle progression (Aim 2). Finally, we will study the role of betaTrcp in controlling the degradation of a novel substrate identified using a biochemical screen: Claspin, a protein that is part of the DMA replication surveillance machinery (Aim 3). Given the crucial function of the cell cycle machinery, altered degradation of cell cycle regulatory proteins is clearly a contributing determinant of the unrestrained proliferation typical of cancer cells. As we continue to unravel the mechanisms of how the scheduled degradation of regulatory proteins by the ubiquitin system controls cellular proliferation, we are committed to the integration of our basic research results with an understanding of malignant transformation. It is anticipated that the results of our studies will have an impact on both basic science and cancer biology.

描述（由申请人提供）：泛素-蛋白酶体系统对关键细胞周期调节蛋白的时间协调破坏代表了一种重要的调节机制，以确保在正确的时间，在正确的室中以单向的方式关闭特定的蛋白质功能。细胞周期机制的许多核心成分的蛋白质水解由两类主要的泛素连接酶控制：SCF （Skp1-Cul1-F-box蛋白）复合物和后期促进复合物/环小体（APC/C）。人体内有68种SCF连接酶，每一种都有不同的F-box蛋白亚基，通过直接将底物募集到连接酶的其余部分，并最终募集到泛素偶联酶，从而提供特异性。尽管F-box蛋白数量众多，但只有三种人SCF泛素连接酶（分别含有F-box蛋白betaTrcp、Fbw7和Skp2）具有确定的底物，其中许多底物参与细胞周期控制（例如，Cdc25A、cyclin E、Emi1、p21、p27、Wee1）。我们提出了一个项目，专注于细胞周期网络的新控制层及其与泛素系统的整合。使用一种新的筛选方法，我们鉴定了六种新的假定的SCF底物，我们将表征其中一种即E2F3的降解机制、调控和生物学功能，E2F3是一种密切参与细胞周期控制的蛋白质（目的1）。我们将进一步鉴定和表征那些生物学上重要的底物，这些底物被F-box蛋白Fbw5破坏，以调节细胞周期进程（目的2）。最后，我们将研究betaTrcp在控制使用生化筛选鉴定的新型底物降解中的作用：Claspin，一种蛋白质，是DMA复制监视机制的一部分（Aim 3）。考虑到细胞周期机制的关键功能，细胞周期调节蛋白降解的改变显然是癌细胞无限制增殖的决定性因素。随着我们继续揭示泛素系统对调节蛋白的预定降解如何控制细胞增殖的机制，我们致力于将我们的基础研究成果与对恶性转化的理解相结合。预计我们的研究结果将对基础科学和癌症生物学产生影响。