Polo-like kinase-1 controls proteasome-dependent degradation of claspin during checkpoint recovery
Polo-like kinase-1 controls proteasome-dependent degradation of claspin during checkpoint recovery
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DOI：
10.1016/j.cub.2006.08.026
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发表时间：
2006-10-10
期刊：
影响因子：
9.2
通讯作者：
Freire, Raimundo
中科院分区：
文献类型：
--
作者：
Mamely, Ivan;van Vugt, Marcel A. T. M.;Freire, Raimundo
dna损伤检查点通过介导细胞周期延迟来应对基因毒性应激或停滞的复制分叉，从而维持基因组的完整性。在对损伤的反应中，检查点激酶ATR磷酸化并激活其效应激酶Chk1，这一过程严重依赖于Claspin[1]。然而，目前尚不清楚这种激酶级联是如何被沉默的。在这里，我们证明了Claspin的丰度是通过蛋白酶体降解调节的。在DNA损伤的反应中，Claspin是短暂稳定的，其表达依赖于Chk1激酶的活性。此外，我们发现Claspin在有丝分裂进入时被降解，这一过程取决于β - trcp - scf泛素连接酶和polo样激酶-1 （Plk1）。我们证明Claspin与β - trcp和Plk1相互作用，并且Claspin中这些成分或β - trcp识别基序的失活可阻止其有丝分裂降解。有趣的是，不可降解的Claspin突变体的表达抑制了dna损伤诱导的检查点阻滞的恢复。因此，我们得出结论，无论是在未受干扰的细胞周期还是在DNA损伤后，Claspin水平都受到严格调节。此外，我们的数据表明，有丝分裂开始时Claspin的降解是细胞从dna损伤诱导的细胞周期停滞中恢复的重要步骤。
DNA-damage checkpoints maintain genomic integrity by mediating a cell-cycle delay in response to genotoxic stress or stalled replication forks. In response to damage, the checkpoint kinase ATR phosphorylates and activates its effector kinase Chk1 in a process that critically depends on Claspin [1]. However, it is not known how exactly this kinase cascade is silenced. Here we demonstrate that the abundance of Claspin is regulated through proteasomal degradation. In response to DNA damage, Claspin is transiently stabilized, and its expression depends on Chk1 kinase activity. In addition, we show that Claspin is degraded upon mitotic entry, a process that depends on the beta-TrCP-SCF ubiquitin ligase and Polo-like kinase-1 (Plk1). We demonstrate that Claspin interacts with both beta-TrCP and Plk1 and that inactivation of these components or the beta-TrCP recognition motif in Claspin prevents its mitotic degradation. Interestingly, expression of a nondegradable Claspin mutant inhibits recovery from a DNA-damage-induced checkpoint arrest. Thus, we conclude that Claspin levels are tightly regulated, both during unperturbed cell cycles and after DNA damage. Moreover, our data demonstrate that the degradation of Claspin at the onset of mitosis is an essential step for the recovery of a cell from a DNA-damage-induced cell-cycle arrest.