Formation of mos RNA granules in the zebrafish oocyte that differ from cyclin B1 RNA granules in distribution, density and regulation
Formation of mos RNA granules in the zebrafish oocyte that differ from cyclin B1 RNA granules in distribution, density and regulation
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DOI：
10.1016/j.ejcb.2016.10.001
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发表时间：
2016-12-01
影响因子：
6.6
通讯作者：
Kotani, Tomoya
中科院分区：
文献类型：
--
作者：
Horie, Mayu;Kotani, Tomoya
许多翻译抑制mrna沉积在卵母细胞细胞质中，参与减数分裂细胞周期的进展和早期发育。mos和cyclin B1 mrna编码促进卵母细胞减数分裂的蛋白，这些mrna的翻译控制对减数分裂细胞的正常分裂过程很重要。我们之前证明了细胞周期蛋白B1 mRNA在斑马鱼和小鼠卵母细胞细胞质中形成RNA颗粒，并且RNA颗粒的形成对于调节mRNA的翻译激活时间至关重要。然而，颗粒形成是否特异性cyclin B1 mRNA仍然未知。在本研究中，我们发现斑马鱼的mos mRNA形成的颗粒与细胞周期蛋白B1 mRNA形成的颗粒不同。荧光原位杂交分析显示，细胞周期蛋白B1 RNA颗粒密集聚集，而大多数RNA颗粒弥散分布在动物的极性细胞质中。蔗糖密度梯度超离心分析表明，大多数RNA颗粒的密度部分低于cyclin B1 mRNA的密度。与细胞周期蛋白B1 RNA颗粒相似，大多数RNA颗粒在卵母细胞成熟开始后被分解，此时聚(A)尾被拉长。然而，当几乎所有的细胞周期蛋白B1颗粒同时被分解时，大部分RNA颗粒首先消失，然后大部分被分解。此外，虽然细胞周期蛋白B1 RNA颗粒的分解依赖于肌动蛋白丝的解聚，但大多数RNA颗粒的某些部分的分解独立于肌动蛋白丝。这些结果表明，胞质通过形成不同的RNA颗粒来调节翻译抑制mrna是卵母细胞中不同mrna翻译控制的关键机制。(C) 2016 Elsevier GmbH版权所有。
Many translationally repressed mRNAs are deposited in the oocyte cytoplasm for progression of the meiotic cell cycle and early development. mos and cyclin B1 mRNAs encode proteins promoting oocyte meiosis, and translational control of these mRNAs is important for normal progression of meiotic cell division. We previously demonstrated that cyclin B1 mRNA forms RNA granules in the zebrafish and mouse oocyte cytoplasm and that the formation of RNA granules is crucial for regulating the timing of translational activation of the mRNA. However, whether the granule formation is specific to cyclin B1 mRNA remains unknown. In this study, we found that zebrafish mos mRNA forms granules distinct from those of cyclin B1 mRNA. Fluorescent in situ hybridization analysis showed that cyclin B1 RNA granules were assembled in dense clusters, while mos RNA granules were distributed diffusely in the animal polar cytoplasm. Sucrose density gradient ultracentrifugation analysis showed that the density of mos RNA granules was partly lower than that of cyclin B1 mRNA. Similar to cyclin B1 RNA granules, mos RNA granules were disassembled after initiation of oocyte maturation at the timing at which the poly(A) tail was elongated. However, while almost all of the granules of cyclin B1 were disassembled simultaneously, a fraction of mos RNA granules firstly disappeared and then a large part of them was disassembled. In addition, while cyclin B1 RNA granules were disassembled in a manner dependent on actin filament depolymerization, certain fractions of mos RNA granules were disassembled independently of actin filaments. These results suggest that cytoplasmic regulation of translationally repressed mRNAs by formation of different RNA granules is a key mechanism for translational control of distinct mRNAs in the oocyte. (C) 2016 Elsevier GmbH. All rights reserved.