RAC1 GTPase plays an important role in γ-irradiation induced G2/M checkpoint activation.
RAC1 GTPase plays an important role in γ-irradiation induced G2/M checkpoint activation.
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DOI：
10.1186/bcr3164
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发表时间：
2012-04-11
期刊：
影响因子：
--
通讯作者：
Cowan KH
中科院分区：
文献类型：
--
作者：
Yan Y;Greer PM;Cao PT;Kolb RH;Cowan KH
为了响应γ辐射（IR）诱导的双链DNA断裂，细胞经历细胞周期停滞，在重新进入细胞周期之前允许DNA修复的时间。G2/M检查点激活涉及共济失调毛细血管扩张突变（ATM）/ATM-和rad 3-相关（ATR）激酶的激活和Cdc 25磷酸酶的抑制，导致Cdc 2激酶的抑制和随后的G2/M细胞周期阻滞。我们实验室的前期研究表明，MCF-7乳腺癌细胞IR暴露后G2/M检查点的激活依赖于细胞外信号调节蛋白激酶1和2（ERK 1/2）信号的激活。在本研究中，我们研究了Ras相关的C3肉毒杆菌毒素底物1（Rac 1）鸟苷三磷酸酶（GTdR）在IR诱导的G2/M检查点反应和ERK 1/2激活中的作用，以及在IR后细胞存活中的作用。在人乳腺癌细胞中检测Rac 1对IR诱导的G2/M检查点应答和ERK 1/2活化的作用。此外，通过使用Rac 1特异性抑制剂评估Rac 1对照射后细胞存活的影响。MCF-7乳腺癌细胞的IR暴露与Rac 1 GT3的显著活化相关。此外，通过使用特异性抑制剂、显性负性Rac 1突变体或特异性siRNA抑制Rac 1导致IR诱导的G2/M期阻滞减弱，并伴随IR诱导的ATM、ATR、Chk 1和Chk 2激酶活化以及Cdc 2-Tyr 15磷酸化的减少。此外，Rac 1抑制或减少Rac 1表达也废除IR诱导的促分裂原活化蛋白激酶激酶1和2（MEK 1/2）和ERK 1/2的磷酸化。最终，Rac 1的抑制显著增加了细胞对IR暴露的敏感性，这涉及诱导细胞凋亡。本报告中的研究表明，Rac 1 GTdR在IR诱导的ERK 1/2信号转导和随后的G2/M检查点反应的激活中起着重要作用。此外，结果还支持Rac 1在辐射处理后促进细胞存活中的作用。
In response to gamma-irradiation (IR)-induced double-strand DNA breaks, cells undergo cell-cycle arrest, allowing time for DNA repair before reentering the cell cycle. G2/M checkpoint activation involves activation of ataxia telangiectasia mutated (ATM)/ATM- and rad3-related (ATR) kinases and inhibition of Cdc25 phosphatases, resulting in inhibition of Cdc2 kinase and subsequent G2/M cell-cycle arrest. Previous studies from our laboratory showed that the G2/M checkpoint activation after IR exposure of MCF-7 breast cancer cells is dependent on the activation of extracellular signal-regulated protein kinase 1 and 2 (ERK1/2) signaling. In the present studies, we investigated the role of Ras-related C3 botulinum toxin substrate 1 (Rac1) guanosine triphosphatase (GTPase) in IR-induced G2/M checkpoint response and ERK1/2 activation, as well as in cell survival after IR. With Rac1-specific inhibitor, dominant negative mutant Rac1 (N17Rac1) and specific small interfering RNA, the effect of Rac1 on IR-induced G2/M checkpoint response and ERK1/2 activation was examined in human breast cancer cells. In addition, the effect of Rac1 on cell survival after irradiation was assessed by using Rac1-specific inhibitor. IR exposure of MCF-7 breast cancer cells was associated with a marked activation of Rac1 GTPase. Furthermore, inhibition of Rac1 by using specific inhibitor, dominant-negative Rac1 mutant, or specific siRNA resulted in attenuation of IR-induced G2/M arrest and concomitant diminution of IR-induced activation of ATM, ATR, Chk1, and Chk2 kinases, as well as phosphorylation of Cdc2-Tyr15. Moreover, Rac1 inhibition or decreased Rac1 expression also abrogated IR-induced phosphorylation of mitogen-activated protein kinase kinase 1 and 2 (MEK1/2) and ERK1/2. Ultimately, inhibition of Rac1 markedly increased cellular sensitivity to IR exposure, which involves induction of apoptosis. Studies in this report suggest that Rac1 GTPase plays an essential role in the activation of IR-induced ERK1/2 signaling and subsequent G2/M checkpoint response. Furthermore, results also support a role for Rac1 in promoting cell survival after irradiation treatment.
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DOI：
10.1083/jcb.200801047
发表时间：
2008-05-05
期刊：
The Journal of cell biology
影响因子：
--
作者：
Michaelson D;Abidi W;Guardavaccaro D;Zhou M;Ahearn I;Pagano M;Philips MR
通讯作者：
Philips MR
DOI：
10.3109/10409238.2011.575764
发表时间：
2011-08
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6.5
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64.8
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