Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
J Biol Chem. 2012 Nov 9;287(46):39193-204. doi: 10.1074/jbc.M112.391854. Epub 2012 Sep 10.
The prevailing model suggests that cell fate after mitotic arrest depends on two independent and competing networks that control cyclin B1 degradation and the generation of death signals. However, recent evidence for Cdk1/cyclin B1-mediated phosphorylation and inactivation of antiapoptotic Bcl-2 proteins suggests the existence of significant cross-talk and interdependence between these pathways. Further, the nature of the mitotic death signals has remained elusive. In this study, we sought to test the hypothesis that fate after mitotic arrest is dictated by the robustness of Cdk1/cyclin B1 signaling to Bcl-2 proteins and to identify signals that may represent a mitotic death signature. We show that when treated with Taxol, slippage-resistant HT29 colon carcinoma cells display robust Cdk1 activity and extensive Mcl-1/Bcl-x(L) phosphorylation and die in mitosis, whereas slippage-prone DLD-1 colon carcinoma cells display weak Cdk1 activity and partial and transient Mcl-1/Bcl-x(L) phosphorylation and die in subsequent interphase or survive. Furthermore, modulation of this signaling axis, either by inhibition of Cdk1 in slippage-resistant HT29 or by enforcing mitotic arrest in slippage-prone DLD-1 cells, evokes a switch in fate, indicating that the strength of Cdk1 signaling to Bcl-2 proteins is a key determinant of outcome. These findings provide novel insight into the pathways that regulate mitotic death, suggest that the robustness of these signaling events may be useful as a marker to define susceptibility to antimitotic drugs, and encourage a revision in the current model describing fate after mitotic arrest.
流行的模型表明,有丝分裂后细胞命运取决于两个独立且相互竞争的网络,这两个网络控制细胞周期蛋白 B1 的降解和死亡信号的产生。然而,最近有证据表明 Cdk1/细胞周期蛋白 B1 介导的抗凋亡 Bcl-2 蛋白磷酸化和失活,表明这些途径之间存在显著的交叉对话和相互依存关系。此外,有丝分裂死亡信号的性质仍然难以捉摸。在这项研究中,我们试图检验这样一个假设,即在有丝分裂后,命运是由 Cdk1/细胞周期蛋白 B1 信号对 Bcl-2 蛋白的稳健性决定的,并确定可能代表有丝分裂死亡特征的信号。我们表明,在用紫杉醇处理时,耐滑 HT29 结肠癌细胞显示出强大的 Cdk1 活性和广泛的 Mcl-1/Bcl-x(L)磷酸化,并在有丝分裂中死亡,而易滑 DLD-1 结肠癌细胞显示出较弱的 Cdk1 活性和部分和短暂的 Mcl-1/Bcl-x(L)磷酸化,并在随后的间期中死亡或存活。此外,通过抑制耐滑 HT29 中的 Cdk1 或通过强制易滑 DLD-1 细胞中的有丝分裂停滞来调节该信号轴,会引发命运的转变,表明 Cdk1 信号对 Bcl-2 蛋白的强度是决定结果的关键决定因素。这些发现为调节有丝分裂死亡的途径提供了新的见解,表明这些信号事件的稳健性可能可用作定义对抗有丝分裂药物敏感性的标志物,并鼓励对描述有丝分裂后命运的当前模型进行修订。