Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
J Gen Virol. 2010 Sep;91(Pt 9):2331-40. doi: 10.1099/vir.0.022004-0. Epub 2010 Jun 2.
RNA segment 8 (NS) of influenza A virus encodes two proteins. The NS1 protein is translated from the unspliced primary mRNA transcript, whereas the second protein encoded by this segment, NS2/NEP, is translated from a spliced mRNA. Splicing of influenza NS1 mRNA is thought to be regulated so that the levels of NS2 spliced transcripts are approximately 10 % of total NS mRNA. Regulation of splicing of the NS1 mRNA has been studied at length, and a number of often-contradictory control mechanisms have been proposed. In this study, we used (32)P-labelled gene-specific primers to investigate influenza A NS1 mRNA splicing regulation. It was found that the efficiency of splicing of NS1 mRNA was maintained at similar levels in both virus infection and ribonucleoprotein-reconstitution assays, and NS2 mRNA comprised approximately 15 % of total NS mRNA in both assays. The effect of NS1 protein expression on the accumulation of viral NS2 mRNA and spliced cellular beta-globin mRNA was analysed, and it was found that NS1 protein expression reduced spliced beta-globin mRNA levels, but had no effect on the accumulation of NS2 mRNA. We conclude that the NS1 protein specifically inhibits the accumulation of cellular RNA polymerase II-driven mRNAs, but does not affect the splicing of its own viral NS1 mRNA.
流感 A 病毒的 RNA 片段 8（NS）编码两种蛋白质。NS1 蛋白是从未剪接的初级 mRNA 转录本翻译而来的，而该片段编码的第二种蛋白质 NS2/NEP 则是从剪接的 mRNA 翻译而来的。据认为，流感 NS1 mRNA 的剪接受到调控，以使 NS2 剪接转录本的水平约为总 NS mRNA 的 10%。NS1 mRNA 剪接的调控已进行了深入研究，并提出了许多常常相互矛盾的控制机制。在这项研究中，我们使用（32）P 标记的基因特异性引物来研究流感 A NS1 mRNA 剪接的调控。结果发现，在病毒感染和核糖核蛋白重建测定中，NS1 mRNA 的剪接效率保持在相似水平，并且在两种测定中，NS2 mRNA 约占总 NS mRNA 的 15%。分析了 NS1 蛋白表达对病毒 NS2 mRNA 和剪接的细胞β-珠蛋白 mRNA 积累的影响，结果发现 NS1 蛋白表达降低了剪接的β-珠蛋白 mRNA 水平，但对 NS2 mRNA 的积累没有影响。我们得出结论，NS1 蛋白特异性地抑制细胞 RNA 聚合酶 II 驱动的 mRNA 的积累，但不影响其自身的病毒 NS1 mRNA 的剪接。
