DNA replication checkpoint prevents precocious chromosome segregation by regulating spindle behavior
DNA replication checkpoint prevents precocious chromosome segregation by regulating spindle behavior
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DOI：
10.1016/j.molcel.2004.11.001
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发表时间：
2004-12-03
期刊：
影响因子：
16
通讯作者：
Surana, U
中科院分区：
文献类型：
--
作者：
Krishnan, V;Nirantar, S;Surana, U
DNA复制检查点维持复制叉的完整性，并防止在复制应激期间染色体分离。Mec1和Rad53（分别为人类ATM/ATR-和chk2样激酶）是酵母中该途径的关键效应物。当使用复制抑制剂处理时，检查点缺陷的mec1或rad53突变体不能维持复制叉的完整性，并继续分割未复制的染色体。我们发现，这种非自然的染色体分离既不需要有丝分裂的发生，也不需要APC的激活、内聚蛋白的分裂或着丝点的双向性。相反，检查点缺陷导致微管相关蛋白Cin8和Stu2的失调，在缺乏染色体内聚和着丝点与微管的双极性附着的情况下，诱导纺锤体过早伸长，导致染色体过早分离。检查点阻止核分裂的能力被微管不稳定马达Kip3和Mad2功能的联合缺乏所废除。因此，DNA复制检查点防止染色体过早分离，不是像人们普遍认为的那样通过抑制进入有丝分裂，而是通过直接调节纺锤体动力学。
The DNA replication checkpoint maintains replication fork integrity and prevents chromosome segregation during replication stresses. Mec1 and Rad53 (human ATM/ATR- and Chk2-like kinases, respectively) are critical effectors of this pathway in yeast. When treated with replication inhibitors, checkpoint-deficient mec1 or rad53 mutant fails to maintain replication fork integrity and proceeds to partition unreplicated chromosomes. We show that this unnatural chromosome segregation requires neither the onset of mitosis nor APC activation, cohesin cleavage, or biorientation of kinetochores. Instead, the checkpoint deficiency leads to deregulation of microtubule-associated proteins Cin8 and Stu2, which, in the absence of both chromosome cohesion and bipolar attachment of kinetochores to microtubules, induce untimely spindle elongation, causing premature chromosome separation. The checkpoint's ability to prevent nuclear division is abolished by combined deficiency of microtubule-destabilizing motor Kip3 and Mad2 functions. Thus, the DNA replication checkpoint prevents precocious chromosome segregation, not by inhibiting entry into mitosis as widely believed, but by directly regulating spindle dynamics.