A MAP KINASE-DEPENDENT SPINDLE ASSEMBLY CHECKPOINT IN XENOPUS EGG EXTRACTS
A MAP KINASE-DEPENDENT SPINDLE ASSEMBLY CHECKPOINT IN XENOPUS EGG EXTRACTS
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DOI：
10.1016/0092-8674(94)90256-9
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发表时间：
1994-11-04
期刊：
影响因子：
64.5
通讯作者：
MURRAY, AW
中科院分区：
文献类型：
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作者：
MINSHULL, J;SUN, H;MURRAY, AW
像早期非洲爪蟾胚胎一样，从非洲爪蟾卵中提取的提取物缺乏细胞周期检查点，该检查点在纺锤体组装完成之前阻止后期发生。然而，在精子核密度很高的情况下，微管解聚会阻止提取物的有丝分裂。被捕的提取物具有高水平的促成熟因子活性，不能降解细胞周期蛋白B，并含有活化的ERK 2/促分裂原活化蛋白（MAP）激酶。此外，纯化的MAP激酶特异性磷酸酶MKP-1表明，MAP激酶活性的建立和维护所需的纺锤体解聚诱导的有丝分裂停滞。增加钙浓度，释放未受精的青蛙卵从他们的自然逮捕中期减数分裂II，有丝分裂逮捕没有影响。
Like early Xenopus embryos, extracts made from Xenopus eggs lack the cell cycle checkpoint that keeps anaphase from occurring before spindle assembly is complete. At very high densities of sperm nuclei, however, microtubule depolymerization arrests the extracts in mitosis. The arrested extracts have high levels of maturation-promoting factor activity, fail to degrade cyclin B, and contain activated ERK2/mitogen-activated protein (MAP) kinase. The addition of the purified MAP kinase-specific phosphatase MKP-1 demonstrates that MAP kinase activity is required for both the establishment and maintenance of the mitotic arrest induced by spindle depolymerization. Increased calcium concentrations, which release unfertilized frog eggs from their natural arrest in metaphase of meiosis II, have no effect on the mitotic arrest.