Effects of 18-glycyrrhetinic acid on serine 368 phosphorylation of connexin43 in rat neonatal cardiomyocytes

Cell Biol Int. 2008 Nov;32(11):1371-9. doi: 10.1016/j.cellbi.2008.08.007. Epub 2008 Aug 19.

Abstract

18Beta-glycyrrhetinic acid (18beta-GA) regulates serine/threonine dephosphorylation of connexin43 (Cx43). Phospho-specific antibodies were used here to determine the effect of 18beta-GA on serine 368-phosphorylated Cx43 (pSer368Cx43) in cultured rat neonatal cardiomyocytes by immunofluorescence microscopy and immunoblot analyses. 18beta-GA caused a time-dependent increase in pSer368Cx43 levels and induced gap junction disassembly, shown by a change in pSer368Cx43 immunostaining from large aggregates to dispersed punctates at cell-cell contact areas. 18beta-GA also induced a time-dependent increase in the levels of serine 729-phosphorylated PKCepsilon, the active form of PKCepsilon. The 18beta-GA-induced increase in pSer368Cx43 levels and changes in pSer368Cx43 staining pattern were abolished by the PKC inhibitor, chelerythrine. Furthermore, 18beta-GA increased the co-immunoprecipitation of Cx43 with PKCepsilon. However, the 18beta-GA-induced increase in pSer368Cx43 levels and increased association of Cx43 with PKCepsilon were inhibited by co-treatment with the protein phosphatase type 1 and type 2A inhibitor, calyculin A. We conclude that 18beta-GA induces Ser368 phosphorylation of Cx43 via PKCepsilon.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence / drug effects
  • Amino Acid Sequence / physiology
  • Animals
  • Animals, Newborn
  • Anti-Inflammatory Agents / pharmacology
  • Antineoplastic Agents / pharmacology
  • Benzophenanthridines / pharmacology
  • Cells, Cultured
  • Connexin 43 / chemistry
  • Connexin 43 / drug effects
  • Connexin 43 / metabolism*
  • Enzyme Activation / drug effects
  • Enzyme Activation / physiology
  • Enzyme Inhibitors / pharmacology
  • Female
  • Gap Junctions / drug effects
  • Gap Junctions / metabolism*
  • Gap Junctions / ultrastructure
  • Glycyrrhetinic Acid / pharmacology*
  • Immunohistochemistry
  • Male
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / metabolism*
  • Myocytes, Cardiac / ultrastructure
  • Phosphorylation / drug effects
  • Protein Kinase C-epsilon / drug effects*
  • Protein Kinase C-epsilon / metabolism
  • Rats
  • Rats, Wistar
  • Serine / chemistry
  • Serine / metabolism
  • Time Factors
  • Up-Regulation / drug effects
  • Up-Regulation / physiology

Substances

  • Anti-Inflammatory Agents
  • Antineoplastic Agents
  • Benzophenanthridines
  • Connexin 43
  • Enzyme Inhibitors
  • Serine
  • chelerythrine
  • Protein Kinase C-epsilon
  • Glycyrrhetinic Acid