Hypoxia induces connexin 43 dysregulation by modulating matrix metalloproteinases via MAPK signaling

Mol Cell Biochem. 2013 Dec;384(1-2):155-62. doi: 10.1007/s11010-013-1793-5. Epub 2013 Sep 4.

Abstract

Connexin 43 (Cx43) is a major structural protein found in the gap junctions of the ventricular myocardium and a major determinant of its electrical properties. The effects of matrix metalloproteinases (MMPs), the mitogen-activated protein kinase (MAPK) signaling pathway, transcription factor NF-kB, and activator protein-1 (AP-1)/c-Jun on the regulation of Cx43 gene expression in H9c2 cardiomyocytes were assessed. The MAPK signaling pathway (MEK/ERK1/2 and PI3K) and transcription factors NF-kB and AP-1/c-Jun were inhibited, then Cx43 expression was assessed using Western blot analysis, and MMP-9 activity was assessed using gelatin zymography. Hypoxia decreased the Cx43 protein level by approximately 30-50 %. Doxycycline (10 μg/mL), an inhibitor of MMP, markedly attenuated the hypoxia-induced downregulation of Cx43 protein expression at 6 h. The hypoxia-induced decrease in Cx43 protein expression was significantly reversed by U0126 (10 μM), a MEK/ERK1/2 inhibitor, at 6 and 12 h; LY294002 (30 μM), a PI3K inhibitor, downregulated Cx43 expression. Hypoxia-induced MMP-9 activation was inhibited by treatment with LY294002, U0126, and, most especially, U0126. JSH-23 (30 μM), an NF-kB inhibitor, and SP600125 (10 μM), an AP-1/c-Jun inhibitor, attenuated the loss of Cx43. These results suggest that MAPK signaling and the activities NF-kB and MMPs play an important roles in the regulation of Cx43 expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anthracenes / pharmacology
  • Butadienes / pharmacology
  • Cell Hypoxia
  • Cell Survival / drug effects
  • Cells, Cultured
  • Chromones / pharmacology
  • Connexin 43 / biosynthesis
  • Connexin 43 / metabolism*
  • Down-Regulation
  • Doxycycline / pharmacology
  • Enzyme Inhibitors / pharmacology
  • Extracellular Signal-Regulated MAP Kinases / antagonists & inhibitors
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Gene Expression Regulation
  • JNK Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • MAP Kinase Signaling System / physiology*
  • Matrix Metalloproteinase 9 / metabolism*
  • Morpholines / pharmacology
  • Myocytes, Cardiac / cytology
  • Myocytes, Cardiac / metabolism
  • NF-kappa B / antagonists & inhibitors
  • NF-kappa B / metabolism
  • Nitriles / pharmacology
  • Phenylenediamines / pharmacology
  • Phosphoinositide-3 Kinase Inhibitors
  • Promoter Regions, Genetic / genetics
  • Rats
  • Transcription Factor AP-1 / metabolism

Substances

  • 4-methyl-N1-(3-phenylpropyl)benzene-1,2-diamine
  • Anthracenes
  • Butadienes
  • Chromones
  • Connexin 43
  • Enzyme Inhibitors
  • Gja1 protein, rat
  • Morpholines
  • NF-kappa B
  • Nitriles
  • Phenylenediamines
  • Phosphoinositide-3 Kinase Inhibitors
  • Transcription Factor AP-1
  • U 0126
  • pyrazolanthrone
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • Extracellular Signal-Regulated MAP Kinases
  • JNK Mitogen-Activated Protein Kinases
  • Matrix Metalloproteinase 9
  • Mmp9 protein, rat
  • Doxycycline