title: Type 1 interferons inhibit myotube formation independently of upregulation of interferon-stimulated gene 15.
abstract: BACKGROUND
  Type 1 interferon (IFN)-inducible genes and their inducible products are upregulated in dermatomyositis muscle. Of these, IFN-stimulated gene 15 (ISG15) is one of the most upregulated, suggesting its possible involvement in the pathogenesis of this disease. To test this postulate, we developed a model of type 1 IFN mediated myotube toxicity and assessed whether or not downregulation of ISG15 expression prevents this toxicity.
  
  
  METHODS
  Mouse myoblasts (C2C12 cell line) were cultured in the presence of type 1 or type 2 IFNs and ISG15 expression assessed by microarray analysis. The morphology of newly formed myotubes was assessed by measuring their length, diameter, and area on micrographs using imaging software. ISG15 expression was silenced through transfection with small interference RNA.
  
  
  RESULTS
  Type 1 IFNs, especially IFN-beta, increased ISG15 expression in C2C12 cells and impaired myotube formation. Silencing of ISG15 resulted in knockdown of ISG15 protein, but without phenotypic rescue of myotube formation.
  
  
  CONCLUSIONS
  IFN-beta affects myoblast differentiation ability and myotube morphology in vitro.These studies provide evidence that ISG15, which is highly upregulated in dermatomyositis muscle, does not appear to play a key role in IFN-beta-mediated C2C12 myoblast cell fusion.
authors.affiliation: Children's Hospital Informatics Program, Boston Children's Hospital, Boston, Massachusetts, USA.
authors.forename: Sara
authors.initials: S
authors.lastname: Franzi
authors.forename: Mohammad
authors.initials: M
authors.lastname: Salajegheh
authors.forename: Remedios
authors.initials: R
authors.lastname: Nazareno
authors.forename: Steven A
authors.initials: SA
authors.lastname: Greenberg
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D016207:Cytokines / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007370:Interferon Type I / Q000494:pharmacology*; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D014452:Ubiquitins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D016207:Cytokines; C489550:G1p2 protein, mouse; D007370:Interferon Type I; D014452:Ubiquitins