The mitochondrial genome encodes abundant small noncoding RNAs

Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
Cell Research (Impact Factor: 12.41). 03/2013; 23(6). DOI: 10.1038/cr.2013.37
Source: PubMed


Small noncoding RNAs identified thus far are all encoded by the nuclear genome. Here, we report that the murine and human mitochondrial genomes encode thousands of small noncoding RNAs, which are predominantly derived from the sense transcripts of the mitochondrial genes (host genes), and we termed these small RNAs mitochondrial genome-encoded small RNAs (mitosRNAs). DICER inactivation affected, but did not completely abolish mitosRNA production. MitosRNAs appear to be products of currently unidentified mitochondrial ribonucleases. Overexpression of mitosRNAs enhanced expression levels of their host genes in vitro, and dysregulated mitosRNA expression was generally associated with aberrant mitochondrial gene expression in vivo. Our data demonstrate that in addition to 37 known mitochondrial genes, the mammalian mitochondrial genome also encodes abundant mitosRNAs, which may play an important regulatory role in the control of mitochondrial gene expression in the cell.Cell Research advance online publication 12 March 2013; doi:10.1038/cr.2013.37.

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Available from: Loredana Moro, Aug 23, 2015
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    • "The studies suggested the presence of unique class of small RNAs in the human mitochondria (Mercer et al., 2011; Ro et al., 2013). Apart from this, a subset of the nuclear encoded microRNAs have been shown to localize to the mitochondria (Das et al., 2012). "
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    • "AGO2 was also hypothesized to function as a molecular conveyor for mitochondrial trafficking of miRNAs [59]. In a further work, Ro et al. [76] showed that both the production of mitochondrial small ncRNAs and the expression of mitochondrial genes were strongly affected in Dicer-null mutant mouse cells but they detected neither Dicer nor AGO2 in highly purified mitochondria from human HEK293T cells. As mentioned above, upon analysis of both intact mitochondria and mitoplasts from human HEK293 cells, Sripada et al. [69] in turn proposed that miRNAs, AGO2 and other RNA interference components would actually assemble into RISC complexes associated with target mRNAs bound to the outer membrane at the mitochondrial surface, building a site-specific platform for the regulation of mRNA turnover and translation (Fig. 2). "
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    • "In addition, some of these drugs increase dopamine levels, which lead to increased formation of ROS. ROS can affect mtDNA copy number and/or damage the mtDNA genome as well as influence chromatin remodeling via ATP level (Maryanovich & Gross, 2013). Furthermore, drugs of abuse influence the epigenetic machinery at several levels, either through the alteration of DNA and histone modifications or through the regulation of DNMTs, miRNAs and transcription factor expression. miRNAs and nuclear-encoded mitochondrial proteins are translocated into the mitochondrion. "
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