title: Heme oxygenase-1 inhibits myoblast differentiation by targeting myomirs.
abstract: OBJECTIVE
  Heme oxygenase-1 (HMOX1) is a cytoprotective enzyme degrading heme to biliverdin, iron ions, and carbon monoxide, whose expression is induced in response to oxidative stress. Its overexpression has been suggested as a strategy improving survival of transplanted muscle precursors.
  
  
  RESULTS
  Here we demonstrated that HMOX1 inhibits differentiation of myoblasts and modulates miRNA processing: downregulates Lin28 and DGCR8, lowers the total pool of cellular miRNAs, and specifically blocks induction of myomirs. Genetic or pharmacological activation of HMOX1 in C2C12 cells reduces the abundance of miR-1, miR-133a, miR-133b, and miR-206, which is accompanied by augmented production of SDF-1 and miR-146a, decreased expression of MyoD, myogenin, and myosin, and disturbed formation of myotubes. Similar relationships between HMOX1 and myomirs were demonstrated in murine primary satellite cells isolated from skeletal muscles of HMOX1(+/+), HMOX1(+/-), and HMOX1(-/-) mice or in human rhabdomyosarcoma cell lines. Inhibition of myogenic development is independent of antioxidative properties of HMOX1. Instead it is mediated by CO-dependent inhibition of c/EBPδ binding to myoD promoter, can be imitated by SDF-1, and partially reversed by enforced expression of miR-133b and miR-206. Control C2C12 myoblasts injected to gastrocnemius muscles of NOD-SCID mice contribute to formation of muscle fibers. In contrast, HMOX1 overexpressing C2C12 myoblasts form fast growing, hyperplastic tumors, infiltrating the surrounding tissues, and disseminating to the lungs.
  
  
  METHODS
  We evidenced for the first time that HMOX1 inhibits differentiation of myoblasts, affects the miRNA processing enzymes, and modulates the miRNA transcriptome.
  
  
  CONCLUSIONS
  HMOX1 improves the survival of myoblasts, but concurrently through regulation of myomirs, may act similarly to oncogenes, increasing the risk of hyperplastic growth of myogenic precursors.
authors.affiliation: Department of Medical Biotechnology, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kozakowska
authors.forename: Maciej
authors.initials: M
authors.lastname: Ciesla
authors.forename: Anna
authors.initials: A
authors.lastname: Stefanska
authors.forename: Klaudia
authors.initials: K
authors.lastname: Skrzypek
authors.forename: Halina
authors.initials: H
authors.lastname: Was
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Jazwa
authors.forename: Anna
authors.initials: A
authors.lastname: Grochot-Przeczek
authors.forename: Jerzy
authors.initials: J
authors.lastname: Kotlinowski
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Szymula
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Bartelik
authors.forename: Milena
authors.initials: M
authors.lastname: Mazan
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Yagensky
authors.forename: Urszula
authors.initials: U
authors.lastname: Florczyk
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Lemke
authors.forename: Anna
authors.initials: A
authors.lastname: Zebzda
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Dyduch
authors.forename: Witold
authors.initials: W
authors.lastname: Nowak
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Szade
authors.forename: Jacek
authors.initials: J
authors.lastname: Stepniewski
authors.forename: Marcin
authors.initials: M
authors.lastname: Majka
authors.forename: Rafal
authors.initials: R
authors.lastname: Derlacz
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Loboda
authors.forename: Jozef
authors.initials: J
authors.lastname: Dulak
authors.forename: Alicja
authors.initials: A
authors.lastname: Jozkowicz
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D051547:Heme Oxygenase-1 / Q000502:physiology*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology* / Q000378:metabolism; D059467:Transcriptome
chemical_list: D035683:MicroRNAs; D051547:Heme Oxygenase-1