BACKGROUND Immature mammalian oocytes are held arrested at prophase I of meiosis by an inhibitory phosphorylation of cyclin-dependent kinase 1 (CDK1). Release from this meiotic arrest and germinal vesicle breakdown is dependent on dephosphorylation of CDK1 by the protein, cell cycle division 25B (CDC25B). Evidence suggests that phosphorylated CDC25B is bound to YWHA (14-3-3) proteins in the cytoplasm of immature oocytes and is thus maintained in an inactive form. The importance of YWHA in meiosis demands additional studies. RESULTS Messenger RNA for multiple isoforms of the YWHA protein family was detected in mouse oocytes and eggs. All seven mammalian YWHA isoforms previously reported to be expressed in mouse oocytes, were found to interact with CDC25B as evidenced by in situ proximity ligation assays. Interaction of YWHAH with CDC25B was indicated by Förster Resonance Energy Transfer (FRET) microscopy. Intracytoplasmic microinjection of oocytes with R18, a known, synthetic, non-isoform-specific, YWHA-blocking peptide promoted germinal vesicle breakdown. This suggests that inhibiting the interactions between YWHA proteins and their binding partners releases the oocyte from meiotic arrest. Microinjection of isoform-specific, translation-blocking morpholino oligonucleotides to knockdown or downregulate YWHA protein synthesis in oocytes suggested a role for a specific YWHA isoform in maintaining the meiotic arrest. More definitively however, and in contrast to the knockdown experiments, oocyte-specific and global deletion of two isoforms of YWHA, YWHAH (14-3-3 eta) or YWHAE (14-3-3 epsilon) indicated that the complete absence of either or both isoforms does not alter oocyte development and release from the meiotic prophase I arrest. CONCLUSIONS Multiple isoforms of the YWHA protein are expressed in mouse oocytes and eggs and interact with the cell cycle protein CDC25B, but YWHAH and YWHAE isoforms are not essential for normal mouse oocyte maturation, fertilization and early embryonic development.

中文翻译：

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YWHA（14-3-3）蛋白同工型及其与CDC25B磷酸酶的相互作用在小鼠卵子发生和卵母细胞成熟中。

背景技术未成熟的哺乳动物卵母细胞通过细胞周期蛋白依赖性激酶1（CDK1）的抑制性磷酸化作用而停滞在减数分裂的前期I。从这种减数分裂停滞和生胚囊泡破裂的释放依赖于CDK1被该蛋白的去磷酸化作用，即细胞周期分裂25B（CDC25B）。有证据表明，磷酸化的CDC25B与未成熟卵母细胞的细胞质中的YWHA（14-3-3）蛋白结合，因此处于非活性状态。YWHA在减数分裂中的重要性需要进一步的研究。结果在小鼠卵母细胞和卵中检测到YWHA蛋白家族的多种同工型的信使RNA。如原位邻近结扎法所证实，先前报道在小鼠卵母细胞中表达的所有七个哺乳动物YWHA亚型均与CDC25B相互作用。Förster共振能量转移（FRET）显微镜显示了YWHAH与CDC25B的相互作用。用R18，一种已知的，合成的，非异构体特异性的，YWHA阻断肽对卵母细胞进行胞质内显微注射促进了生小泡的分解。这表明，抑制YWHA蛋白与其结合伴侣之间的相互作用可将卵母细胞从减数分裂停滞中释放出来。显微注射同种型特异性，翻译阻断性吗啉代寡核苷酸以敲低或下调卵母细胞中的YWHA蛋白合成表明，特定的YWHA同种型在维持减数分裂阻滞中起作用。然而，更确切地说，与敲除实验相反，卵母细胞特异性和YWHA的两个同工型的整体缺失，YWHAH（14-3-3 eta）或YWHAE（14-3-3 epsilon）表示，完全不存在一种或两种同工型不会改变卵母细胞的发育和从减数分裂前期I逮捕中释放。结论YWHA蛋白的多种同工型在小鼠卵母细胞和卵中表达，并与细胞周期蛋白CDC25B相互作用，但是YWHAH和YWHAE同工型对于正常的小鼠卵母细胞成熟，受精和早期胚胎发育不是必需的。