Ethanol Exposure Regulates Expression via Histone Deacetylation at the Promoter in Cultured Cortical Neurons.

-Aminobutyric acid A receptors (GABA-Rs) mediate the majority of inhibitory neurotransmission in the adult brain. The 1-containing GABA-Rs are the most prominent subtype in the adult brain and are important in both homeostatic function and several disease pathologies including alcohol dependence, epilepsy, and stress. Ethanol exposure causes a decrease of 1 transcription and peptide expression both in vivo and in vitro, but the mechanism that controls the transcriptional regulation is unknown. Because ethanol is known to activate epigenetic regulation of gene expression, we tested the hypothesis that ethanol regulates 1 expression through histone modifications in cerebral cortical cultured neurons. We found that class I histone deacetylases (HDACs) regulate ethanol-induced changes in 1 gene and protein expression as pharmacologic inhibition or knockdown of HDAC1-3 prevents the effects of ethanol exposure. Targeted histone acetylation associated with the promoter using CRISPR (clustered regularly interspaced palindromic repeat) dCas9-P300 (a nuclease-null Cas9 fused with a histone acetyltransferase) increases histone acetylation and prevents the decrease of expression. In contrast, there was no effect of a mutant histone acetyltransferase or generic transcriptional activator or targeting P300 to a distant exon. Conversely, using a dCas9-KRAB construct that increases repressive methylation (H3K9me3) does not interfere with ethanol-induced histone deacetylation. Overall our results indicate that ethanol deacetylates histones associated with the promoter through class I HDACs and that pharmacologic, genetic, or epigenetic intervention prevents decreases in 1 expression in cultured cortical neurons.