Overexpression of microRNA-206 in the skeletal muscle from myotonic dystrophy type 1 patients

Abstract

BackgroundMicroRNAs are highly conserved, noncoding RNAs involved in post-transcriptional gene silencing. They have been shown to participate in a wide range of biological processes, including myogenesis and muscle regeneration. The goal of this study is to test the hypothesis that myo-miRs (myo = muscle + miR = miRNA) expression is altered in muscle from patients affected by myotonic dystrophy type 1 (DM1), the most frequently inherited neuromuscular disease in adults. In order to gain better insights about the role of miRNAs in the DM1 pathogenesis, we have also analyzed the muscular expression of miR-103 and miR-107, which have been identified in silico as attractive candidates for binding to the DMPK mRNA.MethodsTo this aim, we have profiled the expression of miR-133 (miR-133a, miR-133b), miR-1, miR-181 (miR-181a, miR-181b, miR-181c) and miR-206, that are specifically induced during myogenesis in cardiac and skeletal muscle tissues. miR-103 and miR-107, highly expressed in brain, heart and muscle have also been included in this study. QRT-PCR experiments have been performed on RNA from vastus lateralis biopsies of DM1 patients (n = 7) and control subjects (n = 4). Results of miRNAs expression have been confirmed by Northern blot, whereas in situ hybridization technique have been performed to localize misexpressed miRNAs on muscle sections from DM1 and control individuals.ResultsOnly miR-206 showed an over-expression in 5 of 7 DM1 patients (threshold = 2, fold change between 1.20 and 13.22, average = 5.37) compared to the control group. This result has been further confirmed by Northern blot analysis (3.37-fold overexpression, R2 = 0.89). In situ hybridization localized miR-206 to nuclear site both in normal and DM1 tissues. Cellular distribution in DM1 tissues includes also the nuclear regions of centralized nuclei, with a strong signal corresponding to nuclear clumps.ConclusionsThis work provides, for the first time, evidences about miRNAs misexpression in DM1 muscle tissues, adding a new element in the pathogenesis of this complex genetic disease.

In situ hybridization-based detection of microRNAs in human diseases

“…Gambardella et al [74] detected overexpression of miR-206 in the skeletal muscle from myotonic dystrophy type 1 (Dm1) patients. ISH localized miR-206 to the nucleus in both normal and Dm1 tissues.…”

RNA-Binding Protein Misregulation in Microsatellite Expansion Disorders

“…In DM1 skeletal muscle biopsies, microRNA (miR) expression patterns are variable between studies with miR-206 overexpression compared to controls (Gambardella et al, 2010) while another study found that miR-1 and miR-335 were upregulated, miRs 29b,c and miR-33 were downregulated, and miR-1, miR133b and miR-206 were mislocalized (Perbellini et al, 2011). Mis-processing of miR-1 occurs in the DM1 heart and this has been linked to MBNL loss-of-function.…”

Myotonic dystrophy

“…They proposed that MBNL1 sequestration in DM1 allowed LIN28 to bind and repress synthesis of miR-1 in DM1 cardiac tissues and increased expression of miR-1 targets such as connexin 43 resulting in cardiac pathology. As yet, there is no consensus with regard to miRNA levels in DM1 skeletal muscles [38 ▪ ,39 ▪ ]. Nevertheless, these studies highlight the potential role of miRNAs in DM1.…”