Studies on ROC1-dependent Ubiquitin E3 Ligases

描述(由申请人提供)：校长最近的作品 研究人员的实验室和其他人发现了泛素的超级家族 含有共同二聚体核心元件的E3连接酶 ROC/APC11环-H2指蛋白与cullin(Cul)/APC2的相互作用 家族蛋白质。该E3连接酶类中的成员包括SCF-ROC1， 后期促进复合体与von Hippel-Lindau(VHL)肿瘤抑制因子 很复杂。拟议的研究生涯的一个主要目标是了解 依赖于ROC 1的E3连接酶调节蛋白质底物的丰度 需要控制细胞周期的进程，激活信号 转导途径和肿瘤抑制活性的执行。 初步研究表明，ROC1-CUL1是一种核心泛素 连接酶，并被接头Skp1和F-box蛋白HOS招募 (β-TRCP同源物)，形成四亚单位SCFHos/β-Trcp-ROC1复合体 启动和催化磷酸化的IKB-α泛素化 Cdc34的存在。这些结果提供了一个概念性的分子 描述ROC/APC11-Cu1/APC2连接酶作用的框架：底物 靶向分子通过适配蛋白招募同源核心连接酶 促进其隔离底物泛素化的元素。 在这份申请中，首席调查员打算继续我们的 侧重于阐明中华民国 依赖于1的E3连接酶参与促进泛素化反应。 具体来说，潘博士建议：i)确定ROC-1介导的机制 泛素连接反应；ii)确定激活的机制 通过Nedd8连接的ROC 1-cull泛素连接酶；以及iii)测定和 新型F-box蛋白Fbx22p44在靶向KLF6、a 诱导转录因子对肝损伤作出反应，以实现泛素化。 这些拟议的研究将提供以下信息：i)增进我们的知识 2)ROC1环-H2指泛素连接酶的作用机制；及 确定管理肝脏损伤和恢复的调节机制 小路。

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.