Regulation of G0-G1 Transition in Hepatocytes

描述(申请人提供)：在肝脏再生过程中，静止的肝细胞重新进入细胞周期，增殖并重新填充病变的肝脏。在许多形式的急性肝损伤中都可以观察到这一过程，特别是那些由病毒、毒素和创伤引起的急性肝损伤。因此，急性肝功能衰竭的预后往往取决于肝细胞的增殖能力超过肝细胞坏死的时间。本文概述的研究的长期目标是利用调节从静止状态退出的事件的最新知识来确定启动肝脏再生的肝脏特异性靶点。这项研究的第一个目的是评估调节细胞周期从静止到活跃的转变的新的细胞周期蛋白依赖性激酶活性。我们认为，在再生过程中，典型的GI细胞周期蛋白之前的细胞周期蛋白依赖的激酶活性在从G0到GI的转变过程中是重要的。这项研究的第二个目的是设计一种基于siRNA的筛选，针对在肝脏再生的启动阶段上调的基因。目标是确定其产物对周期进程是必要的基因。我们希望找出与生理相关的分子，作为促进肝脏增殖的治疗靶点。使用H35大鼠肝细胞系的基于细胞的分析将用于这两种研究路线，该细胞系可以经历从静止到细胞周期重入的转变。

DESCRIPTION (provided by applicant): During liver regeneration, quiescent hepatocytes reenter the cell cycle, proliferate and repopulate the diseased liver. This process is observed in many forms of acute liver injury specifically those caused by viruses, toxins and trauma. Therefore, prognosis in acute liver failure often depends on the ability of proliferation to outlast liver cell necrosis. The long-term objective of the studies outlined here is to use recent knowledge of events that regulate exit from quiescence to identify liver specific targets in the initiation of liver regeneration. The first aim of the study is to evaluate for novel cyclin dependent kinase activities that regulate the transition from quiescence to active cell cycling. We believe that cyclin dependent kinase activities that precede the canonical Gi cyclins are important in transiting from G0 to GI during the regenerative process. The second aim of the study is to design a siRNA based screen that targets genes up regulated in the priming phase of liver regeneration. The goal is to identify genes whose products are necessary for cycle progression. Our hope is to identify physiologically relevant molecules that can be therapeutic targets for enhancement of liver proliferation. A cell based assay using H35 rat liver cell line, which can undergo the transition from quiescence to cell cycle reentry, will be used for both lines of inquiry.