ZFIN ID: ZDB-PUB-101222-33
dickkopf-3-related Gene Regulates the Expression of Zebrafish myf5 Gene through Phosphorylated p38a-dependent Smad4 Activity
Hsu, R.J., Lin, C.C., Su, Y.F., and Tsai, H.J.
Date: 2011
Source: The Journal of biological chemistry   286(8): 6855-6864 (Journal)
Registered Authors: Tsai, Huai-Jen
Keywords: Gene regulation, p38 MAPK, Skeletal muscle, SMAD transcription factor, Zebra fish
MeSH Terms:
  • Animals
  • Enzyme Inhibitors/pharmacology
  • Gene Expression Regulation, Developmental/drug effects
  • Gene Expression Regulation, Developmental/physiology*
  • Gene Knockdown Techniques
  • Imidazoles/pharmacology
  • Intercellular Signaling Peptides and Proteins/genetics
  • Intercellular Signaling Peptides and Proteins/metabolism*
  • MAP Kinase Signaling System/drug effects
  • MAP Kinase Signaling System/physiology
  • Multiprotein Complexes/genetics
  • Multiprotein Complexes/metabolism
  • Myogenic Regulatory Factor 5/biosynthesis*
  • Myogenic Regulatory Factor 5/genetics
  • Oligonucleotides/pharmacology
  • Phosphorylation/drug effects
  • Phosphorylation/physiology
  • Protein Stability
  • Pyridines/pharmacology
  • Smad2 Protein/genetics
  • Smad2 Protein/metabolism
  • Smad3 Protein/genetics
  • Smad3 Protein/metabolism
  • Smad4 Protein/genetics
  • Smad4 Protein/metabolism*
  • Zebrafish/embryology*
  • Zebrafish/genetics
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism*
  • p38 Mitogen-Activated Protein Kinases/antagonists & inhibitors
  • p38 Mitogen-Activated Protein Kinases/genetics
  • p38 Mitogen-Activated Protein Kinases/metabolism*
PubMed: 21159776 Full text @ J. Biol. Chem.
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ABSTRACT
Myf5 is a myogenic regulatory factor that functions in myogenesis. An intronic microRNA, miR-In300, located within zebrafish myf5 intron I, has been reported to silence myf5 through the targeting of dickkopf3 related gene (dkk3r). However, the molecular mechanism underlying the control of myf5 expression by dkk3r is unknown. By injecting dkk3r specific morpholino (dkk3r MO) to knock down Dkk3r, we found that the phosphorylated p38a protein was reduced. Knockdown of p38a resulted in malformed somites and reduced myf5 transcripts, which photocopied the defects induced by injection of dkk3r MO. To block the MAPK pathway, phosphorylation of p38 was inhibited by introduction of SB203580, which caused the down regulation of myf5 expression. The GFP signal was dramatically decreased in somites when we injected p38a MO into embryos derived from transgenic line Tg(myf5(80K):GFP), in which the GFP was driven by myf5 promoter. Although these p38a MO induced defects were rescued by co-injection with p38a mRNA, they were not rescued with p38a mRNA containing a mutation at the phosphorylation domain. Moreover, overexpression of Smad2 or Smad3a enhanced myf5 expression, but the defects induced by the dominant-negative form of either Smad2 or Smad3a equaled those of embryos injected with either dkk3r MO or p38a MO. These results support the involvement of Smad2/3a in p38a mediation. Overexpression of Smad4 enabled the rescue of myf5 defects in the dkk3r MO injected embryos, but knockdown of either dkk3r or p38a caused Smad4 protein to lose stability. Therefore, we concluded that Dkk3r regulates p38a phosphorylation to maintain Smad4 stability, in turn enabling the Smad2/3a/4 complex to form and activate myf5 promoter.
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