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


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
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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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    ABSTRACT: MicroRNAs (miRNAs) are short noncoding RNAs that regulate the expression of their targets in a sequence-dependent manner. For protein-coding transcripts, miRNAs regulate expression levels through binding sites in either the 3' untranslated region (3' UTR) or the amino acid coding sequence (CDS) of the targeted messenger RNA (mRNA). Currently, for the 5' untranslated region (5' UTR) of mRNAs, very few naturally occurring examples exist whereby the targeting miRNA down-regulates the expression of the corresponding mRNA in a seed-dependent manner. Here we describe and characterize two miR-103a-3p target sites in the 5' UTR of GPRC5A, a gene that acts as a tumor suppressor in some cancer contexts and as an ongocene in other cancer contexts. In particular, we show that the interaction of miR-103a-3p with each of these two 5' UTR targets reduces the expression levels of both GPRC5A mRNA and GPRC5A protein in one normal epithelial and two pancreatic cancer cell lines. By ectopically expressing "sponges" that contain instances of the wild-type 5' UTR targets we also show that we can reduce miR-103a-3p levels and increase GPRC5A mRNA and protein levels. These findings provide some first knowledge on the post-transcriptional regulation of this tumor suppressor/oncogene and present additional evidence for the participation of 5' UTRs in miRNA driven post-transcriptional regulatory control.
    RNA 07/2014; 20(9). DOI:10.1261/rna.045757.114 · 4.94 Impact Factor
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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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    ABSTRACT: The production of different types of blood cells including their formation, development, and differentiation is collectively known as haematopoiesis. Blood cells are divided into three lineages erythriod (erythrocytes), lymphoid (B and T cells), and myeloid (granulocytes, megakaryocytes, and macrophages). Haematopoiesis is a complex process regulated by several mechanisms including microRNAs (miRNAs). miRNAs are small RNAs which regulate the expression of a number of genes involved in commitment and differentiation of hematopoietic stem cells. Evidence shows that miRNAs play an important role in haematopoiesis; for example, myeloid and erythroid differentiation is blocked by the overexpression of miR-15a. miR-221, miR-222, and miR-24 inhibit the erythropoiesis, whereas miR-150 plays a role in B and T cell differentiation. miR-146 and miR-10a are downregulated in megakaryopoiesis. Aberrant expression of miRNAs was observed in hematological malignancies including chronic myelogenous leukemia, chronic lymphocytic leukemia, multiple myelomas, and B cell lymphomas. In this review we have focused on discussing the role of miRNA in haematopoiesis.
    Advances in Hematology 12/2013; 2013(8):695754. DOI:10.1155/2013/695754
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    • "In animals, miRNAs are phylogenetically conserved and primarily inhibit transcript translation by binding in the 3′ untranslated region (UTR) sequences of targeted gene transcripts (Bartel, 2004; Lee et al., 1993; Wightman et al., 1993). However, there is growing evidence that miRNAs also posttranscriptionally regulate gene expression through complementary binding in the 5′ UTRs (Lee et al., 2009; Lytle et al., 2007; Moretti et al., 2010) and coding regions (Tay et al., 2008; Zhou et al., 2009). "
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    ABSTRACT: Testicular toxicity is an important safety endpoint in drug development and risk assessment, but reliable and translatable biomarkers for predicting injury have eluded researchers. However, this area shows great potential for improvement, with several avenues currently being pursued. This was the topic of a symposium session during the 2013 Society of Toxicology Annual Meeting in San Antonio, TX, entitled (")Translatable Indicators of Testicular Toxicity: Inhibin B, microRNAs, and Sperm Signatures.(") This symposium brought together stakeholders from academia, government, and industry to present the limitations and drawbacks of currently used indicators of injury, and discussed the ongoing efforts in developing more predictive biomarkers of injury. The presentations highlighted the early challenges of using circulating inhibin B and microRNA levels, and sperm mRNA transcript abundance and DNA methylation profiles, as novel biomarkers of testicular toxicity.
    Toxicological Sciences 09/2013; 136(2). DOI:10.1093/toxsci/kft207 · 3.85 Impact Factor
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