CELL CYCLE GENES AND CELLULAR SENESCENCE AND AGING

正常人类细胞在培养中表现出有限的分裂潜力，称为 衰老。细胞分裂一定的世代数，然后 未能进入后续的S阶段。现有证据表明 衰老细胞有一个完整的途径，可以防止某些方面的 激活细胞周期调节装置。我们的整体利益 是确定没有激活的哪一个方面，以及是否 细胞周期调控基因和蛋白质的引入 促进进入S阶段可以克服这种失活。近期 遗传和生化证据表明，G1期到S期 真核细胞周期的转变，部分是由 蛋白激酶(S)p34cdc2及其相关蛋白的协同作用 调节亚单位，细胞周期蛋白。该计划的主要重点将是 CDK2和CDc2Hs蛋白激酶与G1的作用分析 细胞周期蛋白在细胞衰老和细胞调控中的作用 循环过渡。CDK2是一种与CDC2相关的蛋白激酶，形成一种 不同的CDC2激酶亚家族。目前认为，CDK2， 它与细胞周期蛋白A形成复合体，参与DNA的控制 复制和/或G1-S转换。非洲爪哇CDK2的耗竭 蛋白质，而不是CDC2蛋白，阻止了DNA在周期中的复制 胚胎提取物的体外研究。进一步的证据表明早期的 在细胞周期中的作用是一些CDK2 mRNA持续存在于G0细胞中， 当G0细胞被刺激进入细胞周期时，其mRNA水平 在CDC2Hs mRNAs增加之前，G1增加。 本研究的具体目的是利用G1期细胞周期蛋白、CDK2和 CDC2Hs基因作为工具用于：1)探索静止的表达状态 和衰老细胞与关键的细胞周期调节因子有关，2) 确定去除CDK2和其他相关蛋白对 细胞周期的进展，3)探索CDK2的调控 磷酸化，以及4)以确定是否表达 细胞周期蛋白和p34蛋白激酶可促进静止期或 衰老细胞进入S时相。我们对衰老过程中G1期调控的分析 Cells的目的是识别其功能是 在老化的细胞中负调控。此信息可用于 进一步阐述负性监管的机制 在衰老的细胞中建立。

Normal human cells in culture show a limited division potential known as senescence. Cells divide for a defined number of generations and then fail to enter subsequent S phases. Available evidence suggests that senescent cells have intact a pathway that prevents some aspect of activation of the cell cycle regulatory apparatus. Our overall interests are to determine what aspect of activation is absent, and whether introduction of cell cycle regulatory genes and proteins that normally promote entry into S phase can overcome this inactivation. Recent genetic and biochemical evidence suggests that the G1 to S phase transition in the eukaryotic cell cycle is controlled, in part, by the coordinate action of a protein kinase(s), p34cdc2, and its associated regulatory subunits, cyclins. The principal focus of this program will be the analysis of the role that Cdk2 and Cdc2Hs protein kinases and G1 cyclins play in the process of senescence and the regulation of cell cycle transitions. Cdk2 is a Cdc2-related protein kinase that forms a distinct sub-family of Cdc2 kinases. It is currently believed that Cdk2, which is found complexed with cyclin A, is involved in the control of DNA replication and/or the G1-S transition. Depletion of the Xenopus Cdk2 protein, but not the Cdc2 protein, blocks DNA replication in cycling embryonic extracts in vitro. Further evidence suggestive of an early role in the cell cycle is that some CDK2 mRNA persists in G0 cells and, when G0 cells are stimulated to enter the cell cycle, its mRNA levels increase in G1 prior to the increase in CDC2Hs mRNAs. The specific aims of this research are to use the G1 cyclins, CDK2 and CDC2Hs genes as tools to: 1) explore the expression state of quiescent and senescent cells with respect to key cell cycle regulators, 2) determine the effects of removal of Cdk2 and other relevant proteins on the progression of the cell cycle, 3) to explore regulation of Cdk2 by phosphorylation, and 4) to determine if expression of combinations of cyclins and p34 protein kinases can promote entry of quiescent or senescent cells into S phase. Our analysis of G1 control in senescent cells is aimed at identifying those key regulators whose functions are negatively regulated in aging cells. This information can be used to further elaborate the mechanisms by which negative regulation is established in senescent cells.