eIF4GI plays a role in the miRNA-mediated gene silencing of the poly(A)-tailed m⁷G-capped mRNA.

<p>(<i>A</i>) Schematic diagrams of the reporter mRNAs used here. The abbreviations of each reporter are depicted in parentheses at the left side. (<i>B</i>) The effect of the 5′ cap structure and the poly(A) tail on the miRNA-mediated translational repression. m⁷G-capped/A-capped and/or poly(A)-tailed/nonadenylated FL mRNAs were co-transfected with the nonadenylated m⁷G-capped RL mRNAs in the presence of miControl or miCXCR4 into HeLa cells. After 19 h of incubation, the luciferase activities were measured to obtain the FL/RL activity ratios. (<i>C</i>) Total RNAs from the cells in panel B were extracted, and the relative levels of the mRNAs were analyzed by quantitative RT-PCR analysis. In panels <i>B</i> and <i>C</i>, the values from miControl-treated cells in all experiments were represented as 100% (lane 1). (<i>D</i>) De-repression of the miRNA-mediated gene silencing by siRNAs against translation factors using the RNA reporter system. The overall procedures for experiments and analyses were described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055725#s2" target="_blank">Materials and Methods</a>. All experiments were performed in triplicate. In panels <i>B</i> and <i>D</i>, the P-values are described (Student <i>t</i>-test). Standard deviations are indicated by bars.