Phosphorylation of maskin by Aurora-A participates in the control of sequential protein synthesis during Xenopus laevis oocyte maturation
Phosphorylation of maskin by Aurora-A participates in the control of sequential protein synthesis during Xenopus laevis oocyte maturation
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DOI：
10.1074/jbc.m410584200
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发表时间：
2005-04-08
影响因子：
4.8
通讯作者：
Arlot-Bonnemains, Y
中科院分区：
文献类型：
--
作者：
Pascreau, G;Delcros, JG;Arlot-Bonnemains, Y
在卵子发生结束时，非洲爪蟾VI期卵母细胞在G（2）/M转换（前期）被阻滞，等待孕酮释放阻滞并开始成熟。孕酮触发磷酸化事件的级联反应，例如pK（a）的降低和促成熟因子活性的增加。减数分裂的进程由几种蛋白质的顺序合成控制。例如，MAPK激酶激酶c-Mos是最先产生的蛋白质，而细胞周期蛋白B1仅在减数分裂I后出现。在减数分裂周期后，卵母细胞在减数分裂II中期停滞，c-Mos激酶活性升高（细胞生长抑制因子）。通过使用双杂交筛选，我们已经确定了maskin，一种参与mRNA顺序翻译控制的蛋白质，作为Aurora-A的结合伴侣，Aurora-A是卵母细胞成熟所必需的蛋白激酶。在这里，我们表明，在体外，极光-A直接结合到面具，这两种蛋白质可以从卵母细胞提取物共免疫沉淀，这表明它们在体内关联。我们还证明了Aurora-A磷酸化maskin上的丝氨酸残基保守的酸性卷曲螺旋蛋白从果蝇转化到人类。当在体内通过显微注射模拟maskin磷酸化序列的合成肽来抑制该Ser的磷酸化时，我们观察到过早成熟。在这些条件下，蛋白质，如细胞周期蛋白B1和Cdc 6，通常只在减数分裂II中检测到，大量产生在减数分裂I核膜破裂的发生之前。这一结果有力地表明，Aurora-A对maskin的磷酸化阻止了减数分裂I期间产生减数分裂II蛋白。
At the end of oogenesis, Xenopus laevis stage VI oocytes are arrested at the G(2)/M transition (prophase) waiting for progesterone to release the block and begin maturation. Progesterone triggers a cascade of phosphorylation events such as a decrease of pK(a) and an increase of maturating-promoting factor activity. Progression through meiosis was controlled by the sequential synthesis of several proteins. For instance, the MAPK kinase kinase c-Mos is the very first protein to be produced, whereas cyclin B1 appears only after meiosis I. After the meiotic cycles, the oocyte arrests at metaphase of meiosis II with an elevated c-Mos kinase activity (cytostatic factor). By using a two-hybrid screen, we have identified maskin, a protein involved in the control of mRNA sequential translation, as a binding partner of Aurora-A, a protein kinase necessary for oocyte maturation. Here we showed that, in vitro, Aurora-A directly binds to maskin and that both proteins can be co-immunoprecipitated from oocyte extracts, suggesting that they do associate in vivo. We also demonstrated that Aurora-A phosphorylates maskin on a Ser residue conserved in transforming acidic coiled coil proteins from Drosophila to human. When the phosphorylation of this Ser was inhibited in vivo by microinjection of synthetic peptides that mimic the maskin-phosphorylated sequence, we observed a premature maturation. Under these conditions, proteins such as cyclin B1 and Cdc6, which are normally detected only in meiosis II, were massively produced in meiosis I before the occurrence of the nuclear envelope breakdown. This result strongly suggests that phosphorylation of maskin by Aurora-A prevents meiosis II proteins from being produced during meiosis I.