Regulation of the cell cycle and signaling by CUL-2 E3 complexes

描述(由申请人提供)：库林双环泛素连接酶(CRL2)复合体针对降解的蛋白质，控制动态的细胞过程，包括细胞周期、极性和信号转导。这一建议侧重于了解调节CRL2复合体如何调控的分子通路：肌动蛋白细胞骨架和细胞运动性；RAS和Notch信号通路；以及有丝分裂调节因子Cyclin B。这些CRL2调节的通路对控制细胞增殖、发育和癌症具有重要意义。目的1研究CRL2对胞浆内CDK抑制因子p21Cip1和p27Kip2的调节作用。CRL2LRR1针对胞浆p21的降解来控制肌动蛋白的细胞骨架动力学和细胞运动。建议的实验涉及p21与CRL2LRR1结合的调节，以及某些癌基因绕过CRL2LRR1介导的p21降解的机制。一个独特的CRL2复合体通过负调控RAS途径效应分子RSK1和RSK2的水平，通过间接机制调节细胞质p27的水平。实验涉及RSK1/2的降解是如何调节的；降解的功能后果；以及CRL2复合体的底物识别亚单位的鉴定。目的研究CRL2LRR-1在线虫外阴发育过程中抑制Notch信号转导的分子途径。目的3着重于有丝分裂调节因子细胞周期蛋白B被APC/C复合体(目前被认为是唯一能降解细胞周期蛋白B的泛素连接酶)和CRL2ZYG-11复合体的作用。细胞周期蛋白B-CDK1复合体是驱动细胞进入有丝分裂的关键细胞周期调节因子，细胞周期蛋白B的降解是细胞有丝分裂退出所必需的。发现细胞周期蛋白B的降解是如何被调控的，对于理解有丝分裂的整体调控是至关重要的。以此为目标的实验将描述 Cyclin B与CRL2ZYG-11结合，确定细胞周期调节降解的机制，并探索该途径在哺乳动物中是否保守。 公共卫生相关性：转移性癌症是由能够在全身移动的细胞不受控制的增殖引起的。这项建议阐述了CRL2蛋白质复合体(降解其他蛋白质)如何起作用：抑制促进癌症的RAS和Notch信号通路；阻止细胞运动；以及降解细胞分裂的中央调节因子(细胞周期蛋白B)。该项目将为癌症相关的基本过程提供新的见解，并为癌症治疗的未来发展提供潜力。

DESCRIPTION (provided by applicant): Cullin 2-RING ubiquitin ligase (CRL2) complexes target proteins for degradation to control dynamic cellular processes including the cell cycle, polarity, and signal transduction. This proposal focuses on understanding the molecular pathways that regulate how CRL2 complexes control: the actin cytoskeleton and cell motility; the Ras and Notch signaling pathways; and the mitotic regulator cyclin B. These CRL2-regulated pathways have important implications for the control of cell proliferation, development, and cancer. Aim 1 focuses on CRL2-mediated regulation of the CDK-inhibitors p21Cip1 and p27Kip2 in the cytoplasm. CRL2LRR1 targets the degradation of cytoplasmic p21 to control actin cytoskeletal dynamics and cell motility. Proposed experiments address the regulation of p21 binding to CRL2LRR1, and the mechanism by which certain oncogenes circumvent CRL2LRR1-mediated degradation of p21. A distinct CRL2 complex regulates cytoplasmic p27 levels through an indirect mechanism by negatively regulating the levels of the Ras pathway effectors RSK1 and RSK2. Experiments address how the degradation of RSK1/2 is regulated; the functional consequences of the degradation; and the identification of the substrate-recognition subunit for the CRL2 complex. Aim 2 seeks to identify the molecular pathway by which CRL2LRR-1 represses Notch signaling in the developing C. elegans vulva, through the use of genetic analysis in combination with reporter transgenes. Aim 3 focuses on the paradigm-shifting observation that the mitotic regulator cyclin B is targeted for degradation not only by the APC/C complex (which is currently regarded as the sole ubiquitin ligase for cyclin B degradation) but also by the CRL2ZYG-11 complex. The cyclin B-CDK1 complex is the key cell cycle regulator that drives cells into mitosis; and the degradation of cyclin B is essential for mitotic exit. Discovering how the degradation of cyclin B is regulated is critical for understandin the overall regulation of mitosis. The experiments in this aim will characterize the interaction of cyclin B with CRL2ZYG-11, determine the mechanism through which the degradation is cell cycle regulated, and explore whether the pathway is conserved in mammals. PUBLIC HEALTH RELEVANCE: Metastatic cancer is caused by the unregulated proliferation of cells that are able to move throughout the body. This proposal addresses how CRL2 protein complexes (which degrade other proteins) act to: inhibit the Ras and Notch signaling pathway that promote cancer; block cell movements; and degrade a central regulator of cell division (cyclin B). This project will provide new insights into fundamental cancer-related processes, and provide the potential for the future development of cancer therapies.