Dynamic expression of the RNA-binding protein Sam68 during mouse pre-implantation development
Dynamic expression of the RNA-binding protein Sam68 during mouse pre-implantation development
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DOI：
10.1016/j.gep.2008.01.005
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发表时间：
2008-05-01
影响因子：
1.2
通讯作者：
Sette, Claudio
中科院分区：
文献类型：
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作者：
Paronetto, Maria Paola;Bianchi, Enrica;Sette, Claudio
STAR蛋白Sam68(KHDRBS1)参与转录后mRNA代谢的多个方面。在此，我们研究了Sam68在小鼠胚胎发育早期的表达和亚细胞定位。我们发现，小鼠卵母细胞高水平表达Sam68基因，低水平表达两个高度同源的STAR基因Khdrbs2(当前符号为SLM-1)，而不表达Khdrbs3(当前符号为SLM-2)。Sam68蛋白在卵母细胞减数分裂成熟和早期胚胎发育过程中均有表达。它在减数分裂恢复时释放到细胞质中，受精后在细胞核中缓慢积累。与观察到的其他RNA结合蛋白不同，Sam68的核积累不依赖于从头转录。然而，我们发现，在单细胞胚胎中，放线菌胺或嘌呤霉素抑制了mRNA的翻译，导致了Sam68在细胞质颗粒中的积累。反卷积显微镜分析表明，这些颗粒是参与mRNA翻译起始的蛋白质的聚集部位，如eIF4A1、eIF4E和eIF4G。这些颗粒含有RNA，经RNaseA处理后被溶解，受精卵表达的其他蛋白质，如剪接因子SC35或胞浆激酶ERK2，经mRNA翻译抑制剂处理后没有积聚在这样的结构中，表明Sam68和翻译起始因子在这些颗粒中的定位是一个特定的事件。这些结果表明，Sam68参与了受精卵中母体mRNAs的翻译调控，并参与了受精引发的早期信号事件。(C)2008爱思唯尔B.V.保留所有权利。
The STAR protein Sam68 (KHDRBS1) is involved in several aspects of post-transcriptional mRNA metabolism. Herein, we have investigated the expression and subcellular localization of Sam68 during early mouse embryogenesis. We found that mouse oocytes express high levels of Sam68 mRNA, low levels of the transcript for Khdrbs2 (current symbol for Slm-1) and no Khdrbs3 (current symbol for Slm-2), two highly homologous STAR genes. Sam68 protein is expressed throughout oocyte meiotic maturation and early embryogenesis. It is released in the cytoplasm upon meiotic resumption and it slowly accumulates in the nucleus after fertilization. Unlike what was observed for other RNA-binding proteins, nuclear accumulation of Sam68 was independent of de novo mRNA transcription. However, we found that inhibition of mRNA translation by either cycloheximide or puromycin in one-cell embryos caused the accumulation of Sam68 in cytoplasmic granules. Analysis of these granules by deconvolution microscopy demonstrated that they are sites of accumulation for proteins involved in the initiation of mRNA translation, such as eIF4A1, eIF4E and eIF4G. These granules contained RNA and were dissolved by treatment with RNase A. Other proteins expressed by the zygote, like the splicing factor SC35 or the cytoplasmic kinase ERK2, did not accumulate in such structures after treatment with inhibitors of mRNA translation, indicating that the localization of Sam68 and of the translation initiation factors in these granules is a specific event. These results indicate that Sam68 is involved in translational regulation of maternal mRNAs in the zygote and in the early signaling events triggered by fertilization. (c) 2008 Elsevier B.V. All rights reserved.