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Hum Mol Genet. 2013 Feb 15;22(4):704-16. doi: 10.1093/hmg/dds478. Epub 2012 Nov 8.

Expanded CTG repeats trigger miRNA alterations in Drosophila that are conserved in myotonic dystrophy type 1 patients.

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1
Department of Genetics, University of Valencia, Burjasot 46100, Spain.

Abstract

Myotonic dystrophy type 1 (DM1) is caused by the expansion of CTG repeats in the 3' untranslated region of the DMPK gene. Several missplicing events and transcriptional alterations have been described in DM1 patients. A large number of these defects have been reproduced in animal models expressing CTG repeats alone. Recent studies have also reported miRNA dysregulation in DM1 patients. In this work, a Drosophila model was used to investigate miRNA transcriptome alterations in the muscle, specifically triggered by CTG expansions. Twenty miRNAs were differentially expressed in CTG-expressing flies. Of these, 19 were down-regulated, whereas 1 was up-regulated. This trend was confirmed for those miRNAs conserved between Drosophila and humans (miR-1, miR-7 and miR-10) in muscle biopsies from DM1 patients. Consistently, at least seven target transcripts of these miRNAs were up-regulated in DM1 skeletal muscles. The mechanisms involved in dysregulation of miR-7 included a reduction of its primary precursor both in CTG-expressing flies and in DM1 patients. Additionally, a regulatory role for Muscleblind (Mbl) was also suggested for miR-1 and miR-7, as these miRNAs were down-regulated in flies where Mbl had been silenced. Finally, the physiological relevance of miRNA dysregulation was demonstrated for miR-10, since over-expression of this miRNA in Drosophila extended the lifespan of CTG-expressing flies. Taken together, our results contribute to our understanding of the origin and the role of miRNA alterations in DM1.

PMID:
23139243
DOI:
10.1093/hmg/dds478
[Indexed for MEDLINE]

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