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

描述（由申请人提供）：Cullin 2-RING泛素连接酶（CRL 2）复合物靶蛋白降解，以控制动态细胞过程，包括细胞周期、极性和信号转导。该提案侧重于了解调节CRL 2复合物如何控制的分子途径：肌动蛋白细胞骨架和细胞运动; Ras和Notch信号通路;以及有丝分裂调节因子细胞周期蛋白B。这些CRL 2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CRL 2介导的细胞质中CDK抑制剂p21 Cip 1和p27 Kip 2的调节。CRL 2LRR 1靶向细胞质p21的降解以控制肌动蛋白细胞骨架动力学和细胞运动性。拟议的实验解决了p21与CRL 2LRR 1结合的调节，以及某些癌基因规避CRL 2LRR 1介导的p21降解的机制。一种独特的CRL 2复合物通过负调节Ras途径效应物RSK 1和RSK 2的水平，通过间接机制调节细胞质p27水平。实验解决了RSK 1/2的降解是如何调节的;降解的功能后果;以及鉴定CRL 2复合物的底物识别亚基。目的二是确定CRL 2LRR-1抑制发育中的C. elegans vulva，通过使用遗传分析结合报告转基因。目的3集中于范式转移观察，即有丝分裂调节因子细胞周期蛋白B不仅被APC/C复合物（其目前被认为是细胞周期蛋白B降解的唯一泛素连接酶）降解，而且被CRL 2 ZYG-11复合物降解。细胞周期蛋白B-CDK 1复合物是驱动细胞进入有丝分裂的关键细胞周期调节因子;而细胞周期蛋白B的降解对于有丝分裂的退出是必不可少的。发现细胞周期蛋白B的降解是如何调节的，对于理解有丝分裂的整体调节至关重要。在这一目标的实验将表征的相互作用， 细胞周期蛋白B与CRL 2 ZYG-11，确定降解是细胞周期调节的机制，并探索该途径在哺乳动物中是否保守。

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.