Qi Zhan-Heng, Song Maengseok, Wallace Melisa J, Wang Dan, Newton Philip M, McMahon Thomas, Chou Wen-Hai, Zhang Chao, Shokat Kevan M, Messing Robert O
Ernest Gallo Clinic and Research Center, Department of Neurology, University of California-San Francisco, 5858 Horton Street, Emeryville, CA 94608, USA.
J Biol Chem. 2007 Nov 9;282(45):33052-63. doi: 10.1074/jbc.M707233200. Epub 2007 Sep 17.
Ethanol enhances gamma-aminobutyrate (GABA) signaling in the brain, but its actions are inconsistent at GABA(A) receptors, especially at low concentrations achieved during social drinking. We postulated that the epsilon isoform of protein kinase C (PKCepsilon) regulates the ethanol sensitivity of GABA(A) receptors, as mice lacking PKCepsilon show an increased behavioral response to ethanol. Here we developed an ATP analog-sensitive PKCepsilon mutant to selectively inhibit the catalytic activity of PKCepsilon. We used this mutant and PKCepsilon(-/-) mice to determine that PKCepsilon phosphorylates gamma2 subunits at serine 327 and that reduced phosphorylation of this site enhances the actions of ethanol and benzodiazepines at alpha1beta2gamma2 receptors, which is the most abundant GABA(A) receptor subtype in the brain. Our findings indicate that PKCepsilon phosphorylation of gamma2 regulates the response of GABA(A) receptors to specific allosteric modulators, and, in particular, PKCepsilon inhibition renders these receptors sensitive to low intoxicating concentrations of ethanol.
乙醇可增强大脑中的γ-氨基丁酸（GABA）信号传导，但其作用在GABA（A）受体上并不一致，尤其是在社交饮酒时达到的低浓度下。我们推测蛋白激酶C（PKCε）的ε亚型调节GABA（A）受体的乙醇敏感性，因为缺乏PKCε的小鼠对乙醇的行为反应增强。在此，我们开发了一种对ATP类似物敏感的PKCε突变体，以选择性抑制PKCε的催化活性。我们使用该突变体和PKCε基因敲除小鼠确定PKCε在丝氨酸327处使γ2亚基磷酸化，并且该位点磷酸化的减少增强了乙醇和苯二氮䓬类药物对α1β2γ2受体的作用，α1β2γ2受体是大脑中最丰富的GABA（A）受体亚型。我们的研究结果表明，γ2的PKCε磷酸化调节GABA（A）受体对特定变构调节剂的反应，特别是PKCε抑制使这些受体对低中毒浓度的乙醇敏感。
