title: Overexpression of microRNA-206 in the skeletal muscle from myotonic dystrophy type 1 patients.
abstract: BACKGROUND
  MicroRNAs 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.
  
  
  METHODS
  To 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.
  
  
  RESULTS
  Only 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.
  
  
  CONCLUSIONS
  This 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.
authors.affiliation: Biopathology Department, Tor Vergata University, Rome, Italy. stefanogambardella@gmail.com
authors.forename: Stefano
authors.initials: S
authors.lastname: Gambardella
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Rinaldi
authors.forename: Saverio M
authors.initials: SM
authors.lastname: Lepore
authors.forename: Antonella
authors.initials: A
authors.lastname: Viola
authors.forename: Emanuele
authors.initials: E
authors.lastname: Loro
authors.forename: Corrado
authors.initials: C
authors.lastname: Angelini
authors.forename: Lodovica
authors.initials: L
authors.lastname: Vergani
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Novelli
authors.forename: Annalisa
authors.initials: A
authors.lastname: Botta
mesh_terms: D000328:Adult; D015152:Blotting, Northern; D015153:Blotting, Western; D016022:Case-Control Studies; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D017403:In Situ Hybridization; D008297:Male; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology*; D009223:Myotonic Dystrophy / Q000235:genetics* / Q000473:pathology; D034443:RNA Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014020:Tissue Extracts; D049411:Utrophin / Q000235:genetics / Q000378:metabolism
chemical_list: C546087:MIRN206 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger; D014020:Tissue Extracts; D049411:Utrophin