Block of CDK1-dependent polyadenosine elongation of Cyclin B mRNA in metaphase I-arrested starfish oocytes is released by intracellular pH elevation upon spawning
Block of CDK1-dependent polyadenosine elongation of Cyclin B mRNA in metaphase I-arrested starfish oocytes is released by intracellular pH elevation upon spawning
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中期 I 停滞的海星卵母细胞中细胞周期蛋白 B mRNA 的 CDK1 依赖性多腺苷延伸阻断在产卵时通过细胞内 pH 升高而释放
DOI：
10.1002/mrd.22599
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发表时间：
2016
影响因子：
2.5
通讯作者：
Masatoshi Hara and Kazuyoshi Chiba
中科院分区：
文献类型：
--
作者：
Hiroe Ochi;Saki Aoto;Kazunori Tachibana;Masatoshi Hara and Kazuyoshi Chiba
减数分裂进程需要严格按照时间顺序翻译母体mRNA。在分离的动物卵母细胞中，含有细胞质多聚腺苷酸化元件（CPE）（如ascyclin B）的母体mRNA的翻译通过体外刺激减数分裂恢复激活，诱导CPEB（CPE结合蛋白）磷酸化及其聚腺苷（poly（A））尾的延长;该模型是否可以在体内应用于卵巢中减数分裂中期I的卵母细胞尚不清楚。在这项研究中，我们发现在海星体腔中，在卵巢卵母细胞中，激活的CDK 1（细胞周期蛋白依赖性激酶1）磷酸化CPEB，CPEB被阻滞在中期I，但CPEB的磷酸化不足以延长细胞周期蛋白Bpoly（A）尾部。然而，在产卵后立即，mRNA被聚腺苷酸化，这表明产卵后细胞内pH（pHi）的增加触发了poly（A）尾的伸长。使用由中期I的成熟卵母细胞制成的无细胞系统，我们证明了多聚腺苷酸化在pH低于7.0时确实受到抑制。这些结果表明，在CPEB磷酸化后发挥作用的pH敏感性过程在生理学低pHi（<7.0）下在中期I停滞的卵母细胞中被阻断。产卵后pHi的增加（>7.0）触发细胞周期蛋白BmRNA的多聚腺苷酸化并进入减数分裂II。Reprod. Dev. 83：79-87，2016.© 2015威利期刊公司.
Meiotic progression requires the translation of maternal mRNAs in a strict temporal order. In isolated animal oocytes, translation of maternal mRNAs containing a cytoplasmic polyadenylation element (CPE), such ascyclin B, is activated by in vitro stimulation of meiotic resumption which induces phosphorylation of CPEB (CPE‐binding protein) and elongation of their polyadenosine (poly(A)) tails; whether or not this model can be applied in vivo to oocytes arrested at metaphase of meiosis I in ovaries is unknown. In this study, we found that active CDK1 (cyclin‐dependent kinase 1) phosphorylated CPEB in ovarian oocytes arrested at metphase I in the starfish body cavity, but phosphorylation of CPEB was not sufficient for elongation ofcyclin Bpoly(A) tails. Immediately after spawning, however, mRNA was polyadenylated, suggesting that an increase in intracellular pH (pHi) upon spawning triggers the elongation of poly(A) tails. Using a cell‐free system made from maturing oocytes at metaphase I, we demonstrated that polyadenylation was indeed suppressed at pH below 7.0. These results suggest that a pH‐sensitive process, functioning after CPEB phosphorylation, is blocked under physiologically low pHi(<7.0) in metaphase‐I‐arrested oocytes. The increase in pHi(>7.0) that occurs after spawning triggers polyadenylation ofcyclin BmRNA and progression into meiosis II.Mol. Reprod. Dev. 83: 79–87, 2016. © 2015 Wiley Periodicals, Inc.