Different roles of H-ras for regulation of myosin heavy chain promoters in satellite cell-derived muscle cell culture during proliferation and differentiation

Michael E Scholz, Joachim D Meissner, Renate J Scheibe, Patrick K Umeda, Kin-Chow Chang, Gerolf Gros, Hans-Peter Kubis

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The effect of constitutively activated proto-oncogene H-ras (H-rasQ61L) on the regulation of myosin heavy chain (MHC) promoter activities was investigated in rabbit satellite cell-derived muscle cell culture during the proliferation stage and early and later stages of differentiation, respectively. During proliferation, overexpression of H-rasQ61L did not affect basal level of activity of the slow MHCI/beta or the fast MHCIId/x promoter luciferase reporter gene construct in transient transfection assays. By contrast, H-rasQ61L affected both MHC promoter activities during differentiation, and this effect changes from inactivation after 2 days to activation after 4 days of differentiation. The activating effect of H-rasQ61L on both MHC promoters after 4 days of differentiation was significantly reduced by LY-294002, a specific inhibitor of the phosphoinositol-3-kinase (PI3K), a downstream target of Ras. Furthermore, the protein kinase Akt (protein kinase B), a downstream target of PI3k, was activated 4 days after initiation of differentiation in myotubes overexpressing H-rasQ61L. By contrast, inhibition of another Ras downstream pathway, mitogen-activated protein kinase kinase 1/2-extracellular signal-regulated protein kinase 1/2 (MKK1/2-ERK1/2-MAPK), increased activities of both MHC promoters, indicating a suppressive role of this pathway. Moreover, the Ras-PI3K-Akt signaling pathway is involved in the activation of MHCI/beta and IId/x promoters in a later stage of differentiation of muscle cells, presumably by a known inhibiting effect of activated Akt on the MKK1/2-ERK1/2-MAPK pathway. The experiments demonstrate that during differentiation of muscle cells activated H-ras is an important regulator of MHC isoform promoter function with opposite effects during early and later stages.
Original languageEnglish
Pages (from-to)C1012-C1018
Number of pages7
JournalAmerican Journal of Physiology: Cell Physiology
Volume297
Issue number4
DOIs
Publication statusPublished - 22 Jul 2009

Keywords

  • 1-phosphatidylinositol 3-kinase
  • animals
  • cell differentiation
  • cell proliferation
  • cells, cultured
  • chromones
  • genes, ras
  • MAP kinase signaling system
  • morpholines
  • myosin heavy chains
  • promoter regions, genetic
  • proto-oncogene proteins p21(ras)
  • rabbits
  • satellite cells, skeletal muscle
  • signal transduction

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