Regulation of gap junction coupling through the neuronal connexin Cx35 by nitric oxide and cGMP

Cell Commun Adhes. Jan-Apr 2006;13(1-2):41-54. doi: 10.1080/15419060600631474.


Gap-junctional coupling among neurons is subject to regulation by a number of neurotransmitters including nitric oxide. We studied the mechanisms by which NO regulates coupling in cells expressing Cx35, a connexin expressed in neurons throughout the central nervous system. NO donors caused potent uncoupling of HeLa cells stably transfected with Cx35. This effect was mimicked by Bay 21-4272, an activator of guanylyl cyclase. A pharmacological analysis indicated that NO-induced uncoupling involved both PKG-dependent and PKG-independent pathways. PKA was involved in both pathways, suggesting that PKG-dependent uncoupling may be indirect. In vitro, PKG phosphorylated Cx35 at three sites: Ser110, Ser276, and Ser289. A mutational analysis indicated that phosphorylation on Ser110 and Ser276, sites previously shown also to be phosphorylated by PKA, had a significant influence on regulation. Ser289 phosphorylation had very limited effects. We conclude that NO can regulate coupling through Cx35 and that regulation is indirect in HeLa cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cell Communication
  • Connexins / metabolism*
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Cyclic GMP / metabolism*
  • Cyclic GMP / pharmacology
  • Cyclic GMP-Dependent Protein Kinases / metabolism*
  • Eye Proteins / metabolism*
  • Gap Junctions / drug effects
  • Gap Junctions / metabolism*
  • Guanylate Cyclase / metabolism
  • HeLa Cells
  • Humans
  • Models, Biological
  • Neurons / metabolism
  • Nitric Oxide / metabolism*
  • Nitric Oxide / pharmacology
  • Patch-Clamp Techniques
  • Phosphorylation
  • Serine / metabolism


  • Connexins
  • Eye Proteins
  • connexin 35 protein, vertebrate
  • Nitric Oxide
  • Serine
  • Cyclic AMP-Dependent Protein Kinases
  • Cyclic GMP-Dependent Protein Kinases
  • Guanylate Cyclase
  • Cyclic GMP