Degradation of maternal mRNA in mouse embryos: selective degradation of specific mRNAs after fertilization
Degradation of maternal mRNA in mouse embryos: selective degradation of specific mRNAs after fertilization
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DOI：
10.1002/mrd.20340
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发表时间：
2005-11-01
影响因子：
2.5
通讯作者：
Aoki, F
中科院分区：
文献类型：
--
作者：
Alizadeh, Z;Kageyama, S;Aoki, F
在卵子发生过程中，mRNA 在生长中的卵母细胞中积极转录和积累，但这种转录在卵母细胞长到完全大小之前停止。积累的母体 mRNA 在减数分裂成熟过程中用于卵母细胞中的蛋白质合成，甚至在胚胎中用于维持受精后的发育。因此，积累的母体mRNA的降解在减数分裂成熟期间开始，但其速度很慢。然而，如果某些 mRNA 编码的蛋白质在减数分裂过程中的特定事件中发挥作用并且对受精后的发育有害，那么它们在受精后应该会迅速降解。在本研究中，为了确定受精后母体转录物的选择性降解，我们在减去单细胞中期胚胎的cDNA后构建卵母细胞cDNA文库，寻找受精后早期降解的mRNA。 H1oo、c-mos、tPA（组织型纤溶酶原激活基因）和 Gdf9 被确定为转录物在受精后快速降解的基因。 RT-PCR 分析表明，这些转录本一旦被消除，在植入前发育过程中就不再表达，这表明卵子发生所需的 mRNA 种类（而非早期植入前发育所需）在受精后迅速降解。嵌合 mRNA 的显微注射，其中编码区和 T-非翻译区 (3'UTR) 在 c-mos 和次黄嘌呤磷酸核糖基转移酶 mRNA 之间交换，结果表明 3'UTR 在受精后发生的快速降解中发挥作用。在所有被鉴定为快速降解 mRNA 的 mRNA 种类的 3'UTR 中，在聚腺苷酸 (poly(A)) 信号附近发现了细胞质聚腺苷酸化元件 (CPE)。讨论了选择性降解的机制及其生物学意义。
During oogenesis, mRNA is actively transcribed and accumulated in growing oocytes, but this transcription stops before the oocytes grow to their full size. The accumulated maternal mRNA is used for protein synthesis in the oocytes during meiotic maturation and even in the embryos to sustain development after fertilization. Therefore, the degradation of accumulated maternal mRNA starts during meiotic maturation, but its rate is slow. Nevertheless, some mRNA species should rapidly degrade after fertilization if they encode proteins that play a role in specific events during meiosis and are detrimental for development after fertilization. In this study, to identify the selective degradation of maternal transcripts after fertilization, we sought mRNAs that are degraded in the early hours after fertilization by constructing an oocyte cDNA library after subtracting the cDNA of embryos at the mid one-cell stage. H1oo, c-mos, tPA (tissue type plasminogen activator gene), and Gdf9 were identified as genes whose transcripts undergo rapid degradation after fertilization. RT-PCR analysis showed that none of these transcripts was expressed during pre-implantation development once they were eliminated, suggesting that the mRNA species that are required for oogenesis, but not for early preimplantation development, are degraded rapidly after fertilization. Microinjection of chimeric mRNAs in which the coding and T-untranslated regions (3'UTR) were exchanged between c-mos and hypoxanthine phosphoribosyltransferase mRNAs revealed that the 3'UTR plays a role in the rapid degradation that occurs after fertilization. Cytoplasmic polyadenylation elements (CPEs) was found near a poly(A) signal in the 3'UTR of all the mRNA species identified as rapidly degrading mRNA. The mechanism for the selective degradation is discussed, in relation to its biological significance.