NOVEL CDK2 MECHANISM CONTROLS CELL PROLIFERATION

新型 CDK2 机制控制细胞增殖

• 批准号: 7012829
• 负责人: Warren Jackson Pledger
• 金额: $ 25.2万
• 依托单位: UNIVERSITY OF SOUTH FLORIDA
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-02-07 至 2007-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7012829
• 关键词: T cell receptor; T lymphocyte; cell cycle; cell proliferation; cyclin dependent kinase; cyclins; cytokine receptors; developmental genetics; enzyme activity; gel mobility shift assay; gene deletion mutation; genetic promoter element; immunogenetics; interleukin 2; laboratory mouse; leukopoiesis; messenger RNA; phosphoproteins; phosphorylation; posttranscriptional RNA processing; receptor expression; western blottings

Nontransformed T cells require IL-2 for proliferation, and IL-2Ralpha is an obligatory component of the high affinity biologically relevant IL-2R. Numerous studies have characterized the transcriptional up-regulation of IL-2Ralpha in mitogenically stimulated T cells. On the other hand, and of potential biological importance, post transcriptional control of IL-2Ralpha expression has yet to be adequately explored or definitively demonstrated. Data presented in this proposal clearly show that IL-2Ralpha expression is regulated at the translational level in primary T cells exposed to mitogenic stimuli. We show that increased translation of the IL-2Ralpha transcript is paralleled by the induction of IL-2 signaling pathways, and we suggest that translational up-regulation of IL-2Ralpha requires the activity of the cell cycle regulatory kinase, cdk2. Interestingly, we found that cdk2 expression was also controlled at a post- transcriptional level and, most likely, by a cdk2-dependent mechanism. These studies identify novel actions of cdk2 and suggest that previously unrecognized mechanisms contribute to the expression of IL-2Ralpha and cdk2. We also present data showing that cdk2 activation and IL-2 signaling are interdependent processes in splenic T cells. We suggest that cdk2 activity is required for the efficient translation of IL-2R and that signals generated by the IL-2R facilitate cdk2 activation by maintaining the down-regulation of the cdk2 inhibitor, P27kip1. These interactions and the involvement of cdk2 in the translation of two important cell cycle regulatory molecules - IL-2Ralpha and cdk2 itself - form the focus of our proposal. Specifically, we will examine potential mechanisms by which cdk2 activity might control the translation of IL-2Ralpha in primary splenocytes. We will identify the region of the 5' untranslated region of the IL-2Ralpha mRNA that is responsible for translational regulation and will determine if proteins bind to this region in a manner dependent on cdk2 activity. We will also determine if cdk2 activity modulates the synthesis or the stability of cdk2. Additional experiments will assess the contribution of IL-2 signaling to the continued down-regulation of p27kip1 in TCR-activated splenocytes. Lastly, the mechanism by which TCR activation promotes the expression of cyclin A will be delineated.

未转化的T细胞需要IL-2进行增殖，而IL-2Rα是高亲和力的生物相关IL-2R的必需成分。大量研究表明，在有丝分裂刺激的T细胞中，IL-2Rα转录上调。另一方面，在潜在的生物学意义上，对IL-2Rα表达的转录后控制还没有得到充分的探索或明确的证明。这项建议中的数据清楚地表明，IL-2Rpha的表达在有丝分裂刺激下的原代T细胞的翻译水平上受到调节。我们发现，IL-2Rα转录本的翻译增加与IL-2信号通路的诱导是平行的，我们认为IL-2Rα的翻译上调需要细胞周期调节激酶CDK2的活性。有趣的是，我们发现CDK2的表达也在转录后水平上受到控制，而且很可能是由CDK2依赖的机制控制的。这些研究发现了CDK2的新作用，并表明先前未知的机制有助于IL-2Rpha和CDK2的表达。我们还提供了数据显示，CDK2激活和IL-2信号在脾T细胞中是相互依赖的过程。我们认为，CDK2活性是IL-2R有效翻译所必需的，IL-2R产生的信号通过维持CDK2抑制物P27kip1的下调而促进CDK2的激活。这些相互作用和CDK2参与两个重要的细胞周期调节分子-IL-2Rpha和CDK2本身的翻译形成了我们建议的焦点。具体地说，我们将研究CDK2活性可能控制原代脾细胞中IL-2Ra翻译的潜在机制。我们将确定IL-2Rpha mRNA 5‘非翻译区中负责翻译调控的区域，并将确定蛋白质是否以依赖于CDK2活性的方式与该区域结合。我们还将确定CDK2的活性是否调节CDK2的合成或稳定性。其他实验将评估IL-2信号对TCR激活的脾细胞中p27kip1持续下调的作用。最后，我们将描述TCR激活促进细胞周期蛋白A表达的机制。

项目成果

Roscovitine inhibits STAT5 activity and induces apoptosis in the human leukemia virus type 1-transformed cell line MT-2.

• 发表时间: 2003-12
• 期刊: Cancer research
• 影响因子: 11.2
• 作者: S. Mohapatra;B. Chu;Sheng Wei;J. Djeu;P. Epling-Burnette;T. Loughran;R. Jove;W. J. Pledger