Silencing of microRNAs in vivo with “antagomiRs”

Laboratory of RNA Molecular Biology, The Rockefeller University, New York, New York, United States
Nature (Impact Factor: 41.46). 01/2006; 438(7068):685-9. DOI: 10.1038/nature04303
Source: PubMed


MicroRNAs (miRNAs) are an abundant class of non-coding RNAs that are believed to be important in many biological processes through regulation of gene expression. The precise molecular function of miRNAs in mammals is largely unknown and a better understanding will require loss-of-function studies in vivo. Here we show that a novel class of chemically engineered oligonucleotides, termed 'antagomirs', are efficient and specific silencers of endogenous miRNAs in mice. Intravenous administration of antagomirs against miR-16, miR-122, miR-192 and miR-194 resulted in a marked reduction of corresponding miRNA levels in liver, lung, kidney, heart, intestine, fat, skin, bone marrow, muscle, ovaries and adrenals. The silencing of endogenous miRNAs by this novel method is specific, efficient and long-lasting. The biological significance of silencing miRNAs with the use of antagomirs was studied for miR-122, an abundant liver-specific miRNA. Gene expression and bioinformatic analysis of messenger RNA from antagomir-treated animals revealed that the 3' untranslated regions of upregulated genes are strongly enriched in miR-122 recognition motifs, whereas downregulated genes are depleted in these motifs. Analysis of the functional annotation of downregulated genes specifically predicted that cholesterol biosynthesis genes would be affected by miR-122, and plasma cholesterol measurements showed reduced levels in antagomir-122-treated mice. Our findings show that antagomirs are powerful tools to silence specific miRNAs in vivo and may represent a therapeutic strategy for silencing miRNAs in disease.

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    • "Current delivery methods of potential miRNAs therapeutics are via direct cellular delivery of synthesized miRNA inhibitors and delivery of a systemic or tissue specific expression vector construct containing mimics or anti-miRs [Li and Rana, 2014]. Antagomirs or modified antisense oligonucleotides can be used in mammals to manipulate expression of miRNAs [Krutzfeldt et al., 2005]. Antagomirs containing a 2 0 - O-methyl modified ribose sugars, terminal phosphorothiates, and a cholesterol group at the 3 0 enhances the cellular uptake due to their binding affinity to the cell surface membrane receptors. "
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    • "Off-target effects on miRNA with related sequences must be tested for each individual Antagomir. Of note, the efficiency of miRNA knockdown can be alternatively tested by Northern Blots (Krutzfeldt et al., 2005; Davis et al., 2006) instead of quantitative real time-PCR (qRT- PCR). "
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    • "Mir-21 AMOs and LNAs have been successfully used to knockdown the endogenous miR-21, reducing tumor growth and activating apoptosis in a number of cancers, including breast (Zhu et al., 2008) and colon cancer (Asangani et al., 2008), as well as glioblastoma (Gabriely et al., 2008). An in vivo study with intravenous administration of miR-16, miR-122, miR-192 and miR- 194 targeting AMOs demonstrated that these antagomirs are able to promote efficient and sustained silencing of corresponding miRNAs (Krützfeldt et al., 2005). MiRNA sponges are artificial RNAs containing repetitions of complementary binding sites to a miRNA of interest that consequently stechiometrically compete for miRNA binding with its natural target. "
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