Article

Mechanism of translational regulation by miR-2 from sites in the 5¢ untranslated region or the open reading frame. Rna

European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
RNA (Impact Factor: 4.94). 10/2010; 16(12):2493-502. DOI: 10.1261/rna.2384610
Source: PubMed

ABSTRACT

MicroRNAs (miRs) commonly regulate translation from target mRNA 3' untranslated regions (UTRs). While effective miR-binding sites have also been identified in 5' untranslated regions (UTRs) or open reading frames (ORFs), the mechanism(s) of miR-mediated regulation from these sites has not been defined. Here, we systematically investigate how the position of miR-binding sites influences translational regulation and characterize their mechanistic basis. We show that specific translational regulation is elicited in vitro and in vivo not only from the 3'UTR, but equally effectively from six Drosophila miR-2-binding sites in the 5'UTR or the ORF. In all cases, miR-2 triggers mRNA deadenylation and inhibits translation initiation in a cap-dependent fashion. In contrast, single or dual miR-2-binding sites in the 5'UTR or the ORF yield rather inefficient or no regulation. This work represents the first demonstration that 5'UTR and ORF miR-binding sites can function mechanistically similarly to the intensively investigated 3'UTR sites. Using single or dual binding sites, it also reveals a biological rationale for the high prevalence of miR regulatory sites in the 3'UTR.

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Available from: Francesca Moretti, Jan 24, 2014
    • "A single strand of this mature miRNA is loaded into the miRNA-induced silencing complex (miRISC) which allows the miRNA to base-pair with a specifi c target mRNA. Pairing of a miRNA usually occurs within the 3′UTR of the mRNA, although 5′UTRs and open reading frame pairing has also been reported (McIver et al. 2012b ;Moretti et al. 2010). miRNA nucleotides 2–8 of the 5′ end of the RNA commonly form the 'seed region' of the sequence where perfect pairing takes place and which isessential for effi cient target binding (Fig. 6.2). "
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    • "The potential of miRNA regulation of mRNAs through binding sites that occur in 5 ′ UTRs was demonstrated early on (Lytle et al. 2007; Moretti et al. 2010). However, only a few validated examples of naturally occurring 5 ′ UTR miRNA targets exist in the literature to date (Jopling et al. 2005; Lytle et al. 2007; Orom et al. 2008; Lee et al. 2009; Grey et al. 2010; Vora et al. 2013). "
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    • "The mechanism by which a miRNA can diminish protein expression is unclear, but several proposals are there from different experimental evidences. miRNAs can interfere with translation process at the stage of initiation (Figure 2) or elongation (Figure 3), or target mRNA may be affected by isolating it from ribosomal machinery [8] [9] [10]. "
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