Calmodulin dependent protein kinase increases conductance at gap junctions formed by the neuronal gap junction protein connexin36

Brain Res. 2012 Dec 3;1487:69-77. doi: 10.1016/j.brainres.2012.06.058. Epub 2012 Jul 13.

Abstract

The major neuronal gap junction protein connexin36 (Cx36) exhibits the remarkable property of "run-up", in which junctional conductance typically increases by 10-fold or more within 5-10min following cell break-in with patch pipettes. Such conductance "run-up" is a unique property of Cx36, as it has not been seen in cell pairs expressing other connexins. Because of the recent observation describing CaMKII binding and phosphorylation sites in Cx36 and evidence that calmodulin dependent protein kinase II (CaMKII) may potentiate electrical coupling in neurons of teleosts, we have explored whether CaMKII activates mammalian Cx36. Consistent with this hypothesis, certain Cx36 mutants lacking the CaMKII binding and phosphorylation sites or wild type Cx36 treated with certain cognate peptides corresponding to binding or phosphorylation sites blocked or strongly attenuated run-up of junctional conductance. Likewise, KN-93, an inhibitor of CaMKII, blocked run-up, as did a membrane permeable peptide corresponding to the CaMKII autoinhibitory domain. Furthermore, run-up was blocked by phosphatase delivered within the pipette and not affected by treatment with the phosphatase inhibitor okadaic acid. These results imply that phosphorylation by CaMKII strengthens junctional currents of Cx36 channels, thereby conferring functional plasticity on electrical synapses formed of this protein.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Benzylamines / pharmacology
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / antagonists & inhibitors
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / metabolism
  • Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors
  • Calcium-Calmodulin-Dependent Protein Kinases / physiology*
  • Cell Line, Tumor
  • Connexins / physiology*
  • Electrophysiological Phenomena
  • Enzyme Inhibitors / pharmacology
  • Gap Junctions / drug effects
  • Gap Junctions / physiology*
  • Mice
  • Neural Conduction / drug effects*
  • Neuronal Plasticity / drug effects
  • Patch-Clamp Techniques
  • Phosphorylation
  • Plasmids / genetics
  • Rats
  • Sulfonamides / pharmacology
  • Transfection

Substances

  • Benzylamines
  • Connexins
  • Enzyme Inhibitors
  • Sulfonamides
  • connexin 36
  • KN 93
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium-Calmodulin-Dependent Protein Kinases