An Important Role for CDK2 in G1 to S Checkpoint Activation and DNA Damage Response in Human Embryonic Stem Cells
An Important Role for CDK2 in G1 to S Checkpoint Activation and DNA Damage Response in Human Embryonic Stem Cells
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DOI：
10.1002/stem.620
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发表时间：
2011-04-01
期刊：
影响因子：
5.2
通讯作者：
Lako, Majlinda
中科院分区：
文献类型：
--
作者：
Neganova, Irina;Vilella, Felipe;Lako, Majlinda
准确了解人类胚胎干细胞（hESCs）维持基因组完整性的机制对其潜在的临床应用非常重要。G1检查点的作用是保护基因组完整性，防止DNA受损的细胞进入s期。之前，我们已经证明，hESC中周期蛋白依赖性激酶2 （CDK2）的下调会导致G1停滞、多能性丧失、细胞周期抑制剂p21和p27的上调以及向胚胎外谱系的分化。在这项研究中，我们详细研究了CDK2在细胞过程中的作用，这些过程对维持hESC基因组稳定性至关重要，如G1检查点激活、DNA修复和凋亡。我们的研究结果表明，CDK2的下调通过激活ATM-CHK2-p53-p21通路触发G1检查点。CDK2的下调能够诱导持续的DNA损伤，并引发DNA损伤反应（DDR），其证据是形成不同的γ - h2。AX和RAD52-BRCA1在hESC核中的病灶。CDK2下调导致早期高凋亡；然而，随着DDR的启动，这种情况会随着时间的推移而逐渐减少。我们的质谱分析表明，CDK2确实与大量参与关键细胞过程的蛋白质相互作用，如DNA复制、细胞周期进程、DNA修复、染色质建模，因此，这表明CDK2在hESC中协调细胞增殖、细胞死亡和DNA修复之间的良好平衡中起着至关重要的作用。干细胞2011；29日:651 - 659
A precise understanding of mechanisms used by human embryonic stem cells (hESCs) to maintain genomic integrity is very important for their potential clinical applications. The G1 checkpoint serves to protect genomic integrity and prevents cells with damaged DNA from entering S-phase. Previously, we have shown that downregulation of cyclin-dependent kinase 2 (CDK2) in hESC causes G1 arrest, loss of pluripotency, upregulation of cell cycle inhibitors p21 and p27 and differentiation toward extraembryonic lineages. In this study, we investigate in detail the role of CDK2 in cellular processes, which are crucial to the maintenance of genomic stability in hESC such as G1 checkpoint activation, DNA repair, and apoptosis. Our results suggest that downregulation of CDK2 triggers the G1 checkpoint through the activation of the ATM-CHK2-p53-p21 pathway. Downregulation of CDK2 is able to induce sustained DNA damage and to elicit the DNA damage response (DDR) as evidenced by the formation of distinct gamma-H2.AX and RAD52-BRCA1 foci in hESC nuclei. CDK2 downregulation causes high apoptosis at the early time points; however, this is gradually decreased overtime as the DDR is initiated. Our mass spectrometry analysis suggest that CDK2 does interact with a large number of proteins that are involved in key cellular processes such as DNA replication, cell cycle progression, DNA repair, chromatin modeling, thus, suggesting a crucial role for CDK2 in orchestrating a fine balance between cellular proliferation, cell death, and DNA repair in hESC. STEM CELLS 2011; 29: 651-659