Splicing is required for rapid and efficient mRNA export in metazoans
Splicing is required for rapid and efficient mRNA export in metazoans
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DOI：
10.1073/pnas.96.26.14937
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发表时间：
1999-12-21
影响因子：
11.1
通讯作者：
Reed, R
中科院分区：
文献类型：
--
作者：
Luo, MJ;Reed, R
目前，前 mRNA 剪接是成熟 mRNA 输出到细胞质之前最后已知的核事件之一；目前尚不清楚剪接和 mRNA 输出是否是生化耦合过程。在这项研究中，我们将含有单个内含子的前 mRNA 或缺少内含子的相同 mRNA (Delta i-mRNA) 注射到非洲爪蟾卵母细胞核中。我们发现剪接的 mRNA 比相同的 Delta i-mRNA 输出得更快、更有效。此外，使用过量 Delta i-mRNA 的竞争研究表明，低效输出 df Delta i-mRNA 与有效输出剪接 mRNA 涉及不同的因素。与这一结论一致，剪接的mRNA和Delta i-mRNA虽然序列相同，但在体外组装成不同的信使核糖核蛋白颗粒(mRNP)。引人注目的是，剪接后的 mRNP 中的 mRNA（而非 Delta i-mRNP 中的）可以快速有效地输出。我们得出的结论是，剪接生成了一种特定的核蛋白复合物，该复合物以 mRNA 为输出目标。我们的结果揭示了剪接和有效 mRNA 输出之间的联系，这可能解释了后生动物中许多蛋白质编码基因的有效表达需要内含子的报道。
Pre-mRNA splicing is among the last known nuclear events before export of mature mRNA to the cytoplasm, At present; it is not known whether splicing and mRNA export are biochemically coupled processes. In this study, we have injected pre-mRNAs containing a single intron or the same mRNAs lacking an intron (Delta i-mRNAs) into Xenopus oocyte nuclei. We find that the spliced mRNAs are exported much more rapidly and efficiently than the identical Delta i-mRNAs. Moreover, competition studies using excess Delta i-mRNA indicate that different factor(s) are involved in the inefficient export df Delta i-mRNA vs. the efficient export of spliced mRNA. Consistent with this conclusion, spliced mRNA and Delta i-mRNA, though identical in sequence, are assembled into different messenger ribonucleoprotein particles (mRNP) in vitro. Strikingly, the mRNA in the spliced mRNP, but not in the Delta i-mRNP, is exported rapidly and efficiently. We conclude that splicing generates a specific nucleoprotein complex that targets mRNA for export. Our results, revealing a link between splicing and efficient mRNA export, may explain the reports that an intron is required for efficient expression of many protein-coding genes in metazoans.