title: Expression of miR-1, miR-133a, miR-133b and miR-206 increases during development of human skeletal muscle.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are small RNA molecules that post-transcriptionally regulate gene expression and have been shown to play an important role during development. miR-1, miR-133a, miR-133b and miR-206 are expressed in muscle tissue and induced during muscle cell differentiation, a process that directs myoblasts to differentiate into mature myotubes, which are organized into myofibers. Although miR-1, miR-133a, miR-133b and miR-206 are well-studied in muscle, there is no information about their expression and function during human development. The purpose of this study was to determine the profile of these miRNAs in muscle cells isolated from different stages of human development.
  
  
  RESULTS
  We examined the levels of miR-1, miR-133a, miR-133b and miR-206 during the development of human foetus. All four miRNA levels were found increased during late stages of human foetal muscle development. Increases in the expression levels of these miRNAs were proportional to the capacity of myoblasts to form myotubes. Changes in miRNA levels during human foetal development were accompanied by endogenous alterations in their known targets and also in their inducer, MyoD. Ectopic MyoD expression caused an induction of muscle cell differentiation in vitro, accompanied by an increase in the levels of miR-1, miR-133a, miR-133b and miR-206.
  
  
  CONCLUSIONS
  This study provides data about the profile of four miRNAs in human muscle cells isolated during different stages of foetal development. These results may shed light on the differentiation of muscle cells and regulation of muscle formation through miRNAs, during the development of human foetus.
authors.affiliation: Department of Molecular Genetics, Function & Therapy, The Cyprus Institute of Neurology & Genetics, PO Box 2346, 1683 Nicosia, Cyprus.
authors.forename: Andrie
authors.initials: A
authors.lastname: Koutsoulidou
authors.forename: Nikolaos P
authors.initials: NP
authors.lastname: Mastroyiannopoulos
authors.forename: Denis
authors.initials: D
authors.lastname: Furling
authors.forename: James B
authors.initials: JB
authors.lastname: Uney
authors.forename: Leonidas A
authors.initials: LA
authors.lastname: Phylactou
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D005333:Fetus / Q000033:anatomy & histology / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000254:growth & development* / Q000502:physiology*; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology / Q000502:physiology
chemical_list: C544547:MIRN1 microRNA, human; C548234:MIRN133 microRNA, human; C546087:MIRN206 microRNA, human; D035683:MicroRNAs; D017570:MyoD Protein