Connexin43 hemichannel-mediated regulation of connexin43

PLoS One. 2013;8(2):e58057. doi: 10.1371/journal.pone.0058057. Epub 2013 Feb 27.

Abstract

Background: Many signaling molecules and pathways that regulate gap junctions (GJs) protein expression and function are, in fact, also controlled by GJs. We, therefore, speculated an existence of the GJ channel-mediated self-regulation of GJs. Using a cell culture model in which nonjunctional connexin43 (Cx43) hemichannels were activated by cadmium (Cd(2+)), we tested this hypothesis.

Principal findings: Incubation of Cx43-transfected LLC-PK1 cells with Cd(2+) led to an increased expression of Cx43. This effect of Cd(2+) was tightly associated with JNK activation. Inhibition of JNK abolished the elevation of Cx43. Further analysis revealed that the changes of JNK and Cx43 were controlled by GSH. Supplement of a membrane-permeable GSH analogue GSH ethyl ester or GSH precursor N-acetyl-cystein abrogated the effects of Cd(2+) on JNK activation and Cx43 expression. Indeed, Cd(2+) induced extracellular release of GSH. Blockade of Cx43 hemichannels with heptanol or Cx43 mimetic peptide Gap26 to prevent the efflux of GSH significantly attenuated the Cx43-elevating effects of Cd(2+).

Conclusions: Collectively, our results thus indicate that Cd(2+)-induced upregulation of Cx43 is through activation of nonjunctional Cx43 hemichannels. Our findings thus support the existence of a hemichannel-mediated self-regulation of Cx43 and provide novel insights into the molecular mechanisms of Cx43 expression and function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Cadmium / pharmacology
  • Connexin 43 / antagonists & inhibitors
  • Connexin 43 / metabolism*
  • Enzyme Activation / drug effects
  • Gap Junctions / drug effects
  • Gap Junctions / metabolism*
  • Glutathione / metabolism
  • Glutathione / pharmacology
  • Humans
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • LLC-PK1 Cells
  • Models, Biological
  • Peptides / pharmacology
  • Phosphorylation / drug effects
  • Protein Transport / drug effects
  • Proto-Oncogene Proteins c-jun / metabolism
  • Rats
  • Swine
  • Up-Regulation / drug effects

Substances

  • Connexin 43
  • Gap 26 peptide
  • Peptides
  • Proto-Oncogene Proteins c-jun
  • Cadmium
  • Adenosine Triphosphate
  • JNK Mitogen-Activated Protein Kinases
  • Glutathione

Grant support

This work was supported by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan (17659255 and 20590953 to JY; B21390324 to HM). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.