Poly(A)-binding protein modulates mRNA susceptibility to cap-dependent miRNA-mediated repression
Poly(A)-binding protein modulates mRNA susceptibility to cap-dependent miRNA-mediated repression
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DOI：
10.1261/rna.1795410
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发表时间：
2010-01-01
期刊：
影响因子：
4.5
通讯作者：
Gromeier, Matthias
中科院分区：
文献类型：
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作者：
Walters, Robert W.;Bradrick, Shelton S.;Gromeier, Matthias
微小RNA（microRNAs，miRNAs）通过与靶mRNA的3'非翻译区（UTR）内的特异性位点结合，在转录后调节基因表达。许多研究已经证明了miRNA的抑制作用，并确定了其活性所需的因素。然而，miRNAs调节基因表达的确切机制仍然不清楚。在这里，我们研究了多种miRNA对人类细胞培养物中含有人工或天然存在的3'UTR的多种靶转录物的影响。与以前的研究一致，我们报道了5' m 7 G帽和3' poly（A）尾对于最大限度地抑制miRNA是必不可少的。这些顺式作用元件还赋予miRNA对靶mRNA的易感性，所述靶mRNA在病毒和真核mRNA衍生的5' UTR结构的控制下翻译，所述5' UTR结构能够进行帽非依赖性翻译。此外，我们评估了多聚腺苷酸结合蛋白（PABP）在miRNA功能中的作用，利用多种方法来调节细胞中活性PABP的水平。PABP的表达和活性与miRNA沉默的强度呈负相关，部分原因是靶mRNA去腺苷化的拮抗作用。总之，这些发现进一步定义了调节miRNA功效的顺式和反式作用因子。
MicroRNAs (miRNAs) regulate gene expression post-transcriptionally through binding specific sites within the 3' untranslated regions (UTRs) of their target mRNAs. Numerous investigations have documented repressive effects of miRNAs and identified factors required for their activity. However, the precise mechanisms by which miRNAs modulate gene expression are still obscure. Here, we have examined the effects of multiple miRNAs on diverse target transcripts containing artificial or naturally occurring 3' UTRs in human cell culture. In agreement with previous studies, we report that both the 5' m 7 G cap and 3' poly( A) tail are essential for maximum miRNA repression. These cis-acting elements also conferred miRNA susceptibility to target mRNAs translating under the control of viral- and eukaryotic mRNA-derived 5' UTR structures that enable cap-independent translation. Additionally, we evaluated a role for the poly(A)-binding protein (PABP) in miRNA function utilizing multiple approaches to modulate levels of active PABP in cells. PABP expression and activity inversely correlated with the strength of miRNA silencing, in part due to antagonism of target mRNA deadenylation. Together, these findings further define the cis- and trans-acting factors that modulate miRNA efficacy.