Regulation of cdk2 activity in endothelial cells that are inhibited from growth by cell contact
Regulation of cdk2 activity in endothelial cells that are inhibited from growth by cell contact
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DOI：
10.1161/01.atv.20.3.629
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发表时间：
2000-03-01
影响因子：
8.7
通讯作者：
Wang, J
中科院分区：
文献类型：
--
作者：
Chen, DH;Walsh, K;Wang, J
内皮细胞（EC）在正常血管中是静止的，但在血管损伤后和血管生成期间经历快速的增殖爆发。在这里，我们表明，细胞周期蛋白依赖性激酶-2（cdk 2），细胞周期的G1期和S期的关键调节因子的活性，在增殖的内皮细胞中以高水平表达，但在接触抑制生长的内皮细胞中以低水平表达。尽管激酶活性存在这些差异，但cdk 2及其活化亚基之一细胞周期蛋白E的蛋白水平并不受这些不同生长条件的调节。cdk抑制剂p27在接触抑制但不增殖的EC中高度表达，而细胞周期蛋白A蛋白的水平优先在增殖的EC中表达。在接触抑制生长的培养物中，在与cdk 2或细胞周期蛋白E的免疫沉淀复合物中检测到p27蛋白。通过检测由内皮细胞-细胞接触诱导的热稳定cdk 2抑制活性，表明p27诱导的功能意义，并且可以用抗p27抗体免疫耗竭。在汇合的EC单层，cdk 2激酶活性被激活的刮伤，导致细胞迁移和增殖。损伤诱导的cdk 2激活与p27的下调和细胞周期蛋白A的诱导同时发生。这些数据表明，p27在EC的汇合培养物中被诱导。他们还表明，p27诱导和细胞周期蛋白A下调有助于抑制cdk 2和细胞增殖的细胞接触在EC中。
Endothelial cells (ECs) are quiescent in normal blood vessels but undergo rapid bursts of proliferation after vascular injury and during angiogenesis. Here we show that the activity of cyclin-dependent kinase-2 (cdk2), a key regulator of the G1 and S phases of the cell cycle, is expressed at high levels in proliferating ECs but at low levels in ECs that are contact-inhibited for growth. Despite these differences in kinase activity, the protein levels of cdk2 and 1 of its activating subunits, cyclin E, are not modulated by these different growth conditions. The cdk inhibitor p27 is highly expressed in contact-inhibited but not proliferating ECs, whereas the level of cyclin A protein is preferentially expressed in proliferating ECs. p27 protein was detected in immunoprecipitable complexes with cdk2 or cyclin E in cultures that were contact-inhibited for growth. The functional significance of the p27 induction was indicated by the detection of a heat-stable cdk2 inhibitory activity that was induced by endothelial cell-cell contact and could be immunodepleted with anti-p27 antibodies. In a confluent EC monolayer, cdk2 kinase activity was activated by a scraping injury that led to cell migration and proliferation. The injury-induced activation of cdk2 coincided with the downregulation of p27 and the induction of cyclin A. These data demonstrate that p27 is induced in confluent cultures of ECs. They also indicate that both p27 induction and cyclin A downregulation contribute to the inhibition of cdk2 and cell proliferation by cell-cell contact in ECs.