The antiviral drug ribavirin does not mimic the 7-methylguanosine moiety of the mRNA cap structure in vitro.
The antiviral drug ribavirin does not mimic the 7-methylguanosine moiety of the mRNA cap structure in vitro.
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DOI：
10.1261/rna.2132505
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发表时间：
2005-10
期刊：
影响因子：
4.5
通讯作者：
B. Westman;L. Beeren;E. Grudzien;J. Stȩpiński;R. Worch;J. Zuberek;J. Jemielity;R. Stolarski;E. Darżynkiewicz;R. Rhoads;T. Preiss
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文献类型：
--
作者：
B. Westman;L. Beeren;E. Grudzien;J. Stȩpiński;R. Worch;J. Zuberek;J. Jemielity;R. Stolarski;E. Darżynkiewicz;R. Rhoads;T. Preiss
真核起始因子eIF4E结合mRNA 5'帽结构，并在翻译起始过程中起核心作用。eIF4E及其活性控制机制具有致癌特性，因此已成为抗癌药物开发的靶点。最近的一项研究（Elissis et al. 2004）提供的证据表明，抗病毒核苷利巴韦林及其磷酸化衍生物是mRNA帽的结构模拟物、eIF4E的高亲和力配体以及eIF4E介导的细胞转化和肿瘤生长的有效阻遏物。基于这些发现，我们测试了利巴韦林、三磷酸利巴韦林（RTP）和二核苷酸RpppG在体外抑制翻译的能力。令人惊讶的是，基于利巴韦林的化合物在典型帽类似物有效阻断帽依赖性翻译的浓度下不影响翻译。使用一组通过帽依赖性或病毒内部核糖体进入位点（IRES）依赖性起始翻译的报告mRNA，我们发现这些含利巴韦林的化合物在高浓度（毫摩尔）下确实抑制翻译，但这种抑制与eIF4E翻译要求无关。在mRNA中添加含有利巴韦林的帽并不刺激翻译。用eIF4E和核帽结合复合物CBC进行的荧光滴定实验表明，RTP和RpppG的亲和力比m（7）GTP和m（7）GpppG的亲和力低两到四个数量级。我们的结论是，至少在翻译方面，利巴韦林在体外不作为mRNA帽的功能模拟物。
The eukaryotic initiation factor eIF4E binds the mRNA 5' cap structure and has a central role during translational initiation. eIF4E and the mechanisms to control its activity have oncogenic properties and thus have become targets for anticancer drug development. A recent study (Kentsis et al. 2004) presented evidence that the antiviral nucleoside ribavirin and its phosphorylated derivatives were structural mimics of the mRNA cap, high-affinity ligands for eIF4E, and potent repressors of eIF4E-mediated cell transformation and tumor growth. Based on these findings, we tested ribavirin, ribavirin triphosphate (RTP), and the dinucleotide RpppG for their ability to inhibit translation in vitro. Surprisingly, the ribavirin-based compounds did not affect translation at concentrations where canonical cap analogs efficiently block cap-dependent translation. Using a set of reporter mRNAs that are translated via either cap-dependent or viral internal ribosome entry sites (IRES)-dependent initiation, we found that these ribavirin-containing compounds did inhibit translation at high (millimolar) concentrations, but there was no correlation of this inhibition with an eIF4E requirement for translation. The addition of a ribavirin-containing cap to mRNA did not stimulate translation. Fluorescence titration experiments with eIF4E and the nuclear cap-binding complex CBC indicated affinities for RTP and RpppG that were two to four orders of magnitude lower than those of m(7)GTP and m(7)GpppG. We conclude that, at least with respect to translation, ribavirin does not act in vitro as a functional mimic of the mRNA cap.