MAP kinase links the fertilization signal transduction pathway to the G(1)/S-phase transition in starfish eggs
MAP kinase links the fertilization signal transduction pathway to the G(1)/S-phase transition in starfish eggs
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DOI：
10.1093/emboj/16.14.4333
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发表时间：
1997-07-16
期刊：
影响因子：
11.4
通讯作者：
Kishimoto, T
中科院分区：
文献类型：
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作者：
Tachibana, K;Machida, T;Kishimoto, T
通过对海星成熟卵中MAP激酶活性的调控，探讨了受精启动受精卵S期的机制。这些未受精的海星卵在减数分裂完成后被阻滞在G（1）期，具有较高的MAP激酶活性，但检测不到cdc_2激酶活性。受精或蛋白质合成的抑制均引起MAP激酶活性的降低，随后是DNA合成。失活的MAP激酶与其特定的磷酸酶，CL 100，启动DNA合成在受精的情况下，而组成激活的MAP激酶与MEK抑制受精后的DNA合成的启动。因此，在未受精的成熟海星卵中，已经获得了DNA复制的能力，但是进入S期受到MAP激酶活性的负调控，MAP激酶活性由连续合成的蛋白质而不是cdc 2激酶支持。受精后，MAP激酶活性的下调是触发G（1）/S期转变所必需的和充分的。
The mechanism by which fertilization initiates S-phase in the zygote is examined by manipulating the activity of MAP kinase in mature starfish eggs, These unfertilized eggs, which are arrested at G(1)-phase after the completion of meiosis, have high MAP kinase activity but undetectable cdc2 kinase activity, Either fertilization or inhibition of protein synthesis causes a decrease in MAP kinase activity, which is followed by DNA synthesis. Inactivation of MAP kinase with its specific phosphatase, CL100, initiates DNA synthesis in the absence of fertilization, while constitutive activation of MAP kinase with MEK represses the initiation of DNA synthesis following fertilization. Thus, in unfertilized mature starfish eggs, a capacity for DNA replication is already acquired, but entry into S-phase is negatively regulated by MAP kinase activity that is supported by a continuously synthesized protein(s) but not by cdc2 kinase, Upon fertilization, downregulation of MAP kinase activity is necessary and sufficient for triggering the G(1)/S-phase transition.