Cdc20 proteolysis requires p38 MAPK signaling and Cdh1‐independent APC/C ubiquitination during spindle assembly checkpoint activation by cadmium
Cdc20 proteolysis requires p38 MAPK signaling and Cdh1‐independent APC/C ubiquitination during spindle assembly checkpoint activation by cadmium
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DOI：
10.1002/jcp.22038
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发表时间：
2010-05
影响因子：
5.6
通讯作者：
Ai-Hsin Yen;Jia-Ling Yang
中科院分区：
文献类型：
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作者：
Ai-Hsin Yen;Jia-Ling Yang
Cdc 20是后期促进复合体/细胞周期体（APC/C）泛素连接酶的激活剂，其启动有丝分裂关键调节因子的破坏以促进有丝分裂，同时其受纺锤体组装检查点（SAC）的负调控以防止过早进入后期。p38丝裂原活化蛋白激酶的激活可能有助于有丝分裂阻滞，但其潜在机制尚不清楚。在这里，我们报告了一种新的途径，其中p38信号触发Cdc 20的破坏下SAC引起的镉，人类致癌物。我们发现，镉诱导的前中期阻滞与人类细胞中Cdc 20和细胞周期蛋白A蛋白水平的降低有关，而细胞周期蛋白B1-Cdk 1的活性不受影响。在镉处理的异步细胞或G2富集细胞中，Cdc 20半衰期沿着其通过26 S蛋白酶体的泛素化和降解而显著缩短。APC 3的消耗显著抑制镉诱导的Cdc 20泛素化和蛋白水解，而APC/C的另一种激活剂Cdh 1的消耗则没有。有趣的是，阻断p38活性恢复Cdc 20水平，继续有丝分裂镉下，而抑制JNK活性没有影响。镉诱导的Cdc 20蛋白水解在p38α的瞬时耗竭或p38的显性负性形式的稳定表达期间也受到抑制。抑制p38可阻断镉对Mad 2-Cdc 20-APC 3复合物的诱导作用。此外，MKK 6-p38信号的强制表达可以促进Cdc 20在Cdh 1非依赖性APC/C通路中的降解。总之，Cdc 20的加速泛素化和蛋白水解对于SAC激活期间通过p38信号传导介导的前中期阻滞是必不可少的。J.细胞。223：327-334，2010。© 2010 Wiley利斯公司
Cdc20, an activator of the anaphase promoting complex/cyclosome (APC/C) ubiquitin ligase, initiates the destruction of key mitotic regulators to facilitate mitosis, while it is negatively regulated by the spindle assembly checkpoint (SAC) to prevent premature anaphase entry. Activation of the p38 mitogen‐activated protein kinase could contribute to mitotic arrest, but the underlying mechanism is unknown. Here we report a novel pathway in which the p38 signaling triggers Cdc20 destruction under SAC elicited by cadmium, a human carcinogen. We found that the cadmium‐induced prometaphase arrest was linked to decreased Cdc20 and accumulated cyclin A protein levels in human cells, whereas the activity of cyclin B1–Cdk1 was unaffected. The Cdc20 half‐life was markedly shortened along with its ubiquitination and degradation via 26S proteasome in cadmium‐treated asynchronous or G2‐enriched cells. Depletion of APC3 markedly suppressed the cadmium‐induced Cdc20 ubiquitination and proteolysis, while depletion of Cdh1, another activator of APC/C, did not. Intriguingly, blockage of p38 activity restored the Cdc20 levels for continuing mitosis under cadmium, while inhibition of JNK activity had no effect. The cadmium‐induced Cdc20 proteolysis was also suppressed during transient depletion of p38α or stable expression a dominant negative form of p38. Inhibition of p38 abolished the induction of Mad2–Cdc20–APC3 complex by cadmium. Moreover, forced expression of MKK6–p38 signaling could promote Cdc20 degradation in a Cdh1‐independent APC/C pathway. In summary, accelerated ubiquitination and proteolysis of Cdc20 is essential for prometaphase arrest that is mediated via the p38 signaling during SAC activation. J. Cell. Physiol. 223: 327–334, 2010. © 2010 Wiley‐Liss, Inc.