Protein kinase Cε regulates γ-aminobutyrate type A receptor sensitivity to ethanol and benzodiazepines through phosphorylation of γ2 subunits

Abstract

Ethanol enhances γ-aminobutyrate (GABA) signaling in the brain, but its actions are inconsistent at GABAA receptors, especially at low concentrations achieved during social drinking. We postulated that the ε isoform of protein kinase C (PKCε) regulates the ethanol sensitivity of GABAA receptors, as mice lacking PKCε show an increased behavioral response to ethanol. Here we developed an ATP analog-sensitive PKCε mutant to selectively inhibit the catalytic activity of PKCε. We used this mutant and PKCε-/- mice to determine that PKCε phosphorylates γ2 subunits at serine 327 and that reduced phosphorylation of this site enhances the actions of ethanol and benzodiazepines at α1β2γ2 receptors, which is the most abundant GABAA receptor subtype in the brain. Our findings indicate that PKCε phosphorylation of γ2 regulates the response of GABAA receptors to specific allosteric modulators, and, in particular, PKCε inhibition renders these receptors sensitive to low intoxicating concentrations of ethanol. © 2007 by The American Society for Biochemistry and Molecular Biology, Inc.