Studies on ROC1-dependent Ubiquitin E3 Ligases

描述（由申请人提供）：最近的工作从校长 研究人员的实验室和其他人发现了一个超家族的泛素 E3连接酶，其含有通过组合形成的共同二聚体核心元件 ROC/APC 11 RING-H2指蛋白和cullin（CUL）/APC 2之间的相互作用 家族蛋白质该E3连接酶类别中的成员包括SCF-ROC 1， 后期促进复合物和von Hippel-Lindau（VHL）肿瘤抑制因子 复杂.拟议的研究生涯的一个主要目标是了解如何 ROC 1依赖性E3连接酶调节蛋白质底物的丰度 控制细胞周期的进程，信号的激活， 转导途径和肿瘤抑制活性的执行。 初步研究表明，ROC 1-CUL 1作为核心泛素发挥功能 连接酶，并由衔接子Skpl和F-box蛋白HOS募集 （β-TRCP同源物），以形成四亚基SCFHos/β-Trcp-ROC 1复合物 启动和催化磷酸化的IKB-α的泛素化， Cdc 34的存在。这些结果提供了一个概念性的分子 描述ROC/APC 11-CUL/APC 2连接酶作用的框架：底物 靶向分子通过衔接蛋白募集同源核心连接酶 元件，以促进其螯合底物的泛素化。 在本申请中，主要研究者打算继续我们的 调查的重点是阐明的机制， 1-依赖性E3连接酶参与促进泛素化反应。 具体而言，潘博士建议：i）确定ROC 1介导的 泛素连接反应; ii）定义激活的潜在机制 iii）通过Nedd 8缀合测定ROC 1-CUL 1泛素连接酶的活性;和 描述新型F-box蛋白Fbx 22 p44在靶向KLF 6中的作用， 转录因子诱导的响应肝损伤，泛素化。 这些拟议的研究将提供信息，以：i）推进我们的知识 ROC 1 RING-H2指泛素连接酶的作用机制;和ii） 确定肝损伤和恢复的调控机制 途径。

DESCRIPTION (provided by applicant): Recent work from the principal investigator's laboratory and others has uncovered a super-family of ubiquitin E3 ligases containing a common dimeric core element formed by combinatorial interactions between the ROC/APC11 RING-H2 finger protein and cullin (CUL)/APC2 family proteins. Members among this E3 ligase class include SCF-ROC1, Anaphase-Promoting Complex and the von Hippel-Lindau (VHL) tumor suppressor complex. A major goal of the proposed research career is to understand how the ROC 1-dependent E3 ligases regulate the abundance of protein substrates required to control the progression of the cell cycle, the activation of signal transduction pathways and the execution of tumor suppressor activities. The initial studies have shown that ROC1-CUL1 functions as a core ubiquitin ligase and is recruited by an adapter, Skpl, and an F-box protein, HOS (beta-TRCP homologue), to form a four-subunit SCFHos/beta-Trcp-ROC1 complex that initiates and catalyzes the ubiquitination of phosphorylated IKB-alpha in the presence of Cdc34. These results have provided a conceptual molecular framework depicting the action of the ROC/APC11-CUL/APC2 ligases: a substrate targeting molecule, via an adapter protein, recruits a cognate core ligase element to promote the ubiquitination of its sequestered substrate. In this application, the principal investigator intends to continue our investigation focusing on the elucidation of the mechanisms by which the ROC 1-dependent E3 ligases engage to promote ubiquitination reactions. Specifically Dr. Pan proposes to: i) determine the mechanism of ROC 1-mediated Ubiquitin ligation reaction; ii) define the mechanism underlying the activation of the ROC 1-CULl ubiquitin ligase by Nedd8 conjugation; and iii) determine and characterize role of the novel F-box protein, Fbx22p44 in targeting KLF6, a transcription factor induced in response to liver injury, for ubiquitination. These proposed studies will provide information that: i) advances our knowledge of the mechanism of action of the ROC1 RING-H2 finger ubiquitin ligase; and ii) identify regulatory mechanisms governing the liver injury and recovery pathways.