Expression and regulation of gap junctions in rat cholangiocytes

Hepatology. 2002 Sep;36(3):631-40. doi: 10.1053/jhep.2002.35274.


Hepatocytes and other digestive epithelia exchange second messengers and coordinate their functions by communicating through gap junctions. However, little is known about intercellular communication in cholangiocytes. The aim of this study was to examine expression and regulation of gap junctions in cholangiocytes. Connexin expression was determined by confocal immunofluorescence in rat bile ducts and in normal rat cholangiocyte (NRC) cells, a polarized cholangiocyte cell line. Intercellular Ca(2+) signaling was monitored by fluorescent microscopy. Microinjection studies assessed regulation of gap junction permeability in NRC cells and in SKHep1 cells, a liver-derived cell line engineered to express connexin 43. Immunochemistry showed that cholangiocytes from normal rat liver as well as the NRC cells express connexin 43. Localization of apical, basolateral, and tight junction proteins confirmed that NRC cells are well polarized. Apical exposure to ATP induced Ca(2+) oscillations that were coordinated among neighboring NRC cells, and inhibition of gap junction conductance desynchronized the Ca(2+) oscillations. NRC cells transfected with a connexin 43 antisense were significantly less coupled. Transcellular dye spreading was inhibited by activation of protein kinase A or protein kinase C. The same was observed in transfected SKHep1 cells, which expressed only connexin 43. Rat cholangiocytes and NRC cells express connexin 43, which permits synchronization of Ca(2+) signals among cells. Permeability of connexin 43-gap junctions is negatively regulated by protein kinases A and C. In conclusion, cholangiocytes have the capacity for intercellular communication of second messenger signals via gap junctions in a fashion that is under hormonal control.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / pharmacology
  • Animals
  • Bile Ducts / cytology*
  • Bile Ducts / metabolism*
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology
  • Cell Line
  • Cell Polarity / physiology
  • Connexin 43 / analysis
  • Connexin 43 / genetics
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Fluorescent Dyes / pharmacokinetics
  • Gap Junctions / chemistry
  • Gap Junctions / metabolism*
  • Gene Expression / physiology
  • Isoquinolines / pharmacokinetics
  • Rats
  • Second Messenger Systems / physiology
  • Transfection


  • Connexin 43
  • Fluorescent Dyes
  • Isoquinolines
  • Adenosine Triphosphate
  • lucifer yellow
  • Cyclic AMP-Dependent Protein Kinases