Hambidge S J, Sarnow P
Department of Microbiology and Immunology, University of Colorado Health Sciences Center, Denver 80262.
J Virol. 1991 Nov;65(11):6312-5. doi: 10.1128/JVI.65.11.6312-6315.1991.
We have used an RNA transfection assay to study the translation of cellular and viral mRNAs with and without 5'-terminal m7GpppG cap structures in human tissue culture cells. HeLa cells were transfected with in vitro-transcribed hybrid RNA molecules containing the 5' noncoding regions of either luciferase or poliovirus linked to the coding region of the firefly luciferase gene. Transcripts containing a capped luciferase 5' noncoding region produced luciferase, while similar uncapped transcripts did not. In contrast, transcripts containing a capped 5' noncoding region of poliovirus accumulated 10-fold-lower levels of luciferase than similar transcripts without a terminal cap structure. Inhibition of poliovirus mRNA translation by a 5'-terminal cap structure was not observed in in vitro translation systems. This finding indicates that factors involved in cap-independent translation of poliovirus RNA are quantitatively or qualitatively different in human tissue culture cells and in in vitro translation systems. Furthermore, this study emphasizes the importance of studying translational control of mRNAs in intact cells.
我们利用RNA转染试验，在人类组织培养细胞中研究了具有和不具有5'-末端m7GpppG帽结构的细胞和病毒mRNA的翻译情况。将含有与萤火虫荧光素酶基因编码区相连的荧光素酶或脊髓灰质炎病毒5'非编码区的体外转录杂交RNA分子转染入HeLa细胞。含有加帽荧光素酶5'非编码区的转录本产生了荧光素酶，而类似的未加帽转录本则没有。相比之下，含有脊髓灰质炎病毒加帽5'非编码区的转录本积累的荧光素酶水平比没有末端帽结构的类似转录本低10倍。在体外翻译系统中未观察到5'-末端帽结构对脊髓灰质炎病毒mRNA翻译的抑制作用。这一发现表明，参与脊髓灰质炎病毒RNA不依赖帽结构翻译的因子在人类组织培养细胞和体外翻译系统中在数量或质量上存在差异。此外，这项研究强调了在完整细胞中研究mRNA翻译控制的重要性。
