Michael Buszczak, Jorge H. Pinzón, Adrian Rothenfluh, Nevine A. Shalaby, Addison R. Reed, Aylin R. Rodan
Long-lasting transcriptional changes underlie a number of adaptations that contribute to alcohol use disorders (AUD). Chromatin remodeling, including histone methylation, can confer distinct, long-lasting transcriptional changes, and histone methylases are known to play a role in the development of addiction. Conversely, little is known about the relevance of Jumonji (JmjC) domain-containing demethylases in AUDs. We systematically surveyed the alcohol-induced phenotypes of null mutations in all 13 Drosophila JmjC genes.
We used a collection of JmjC mutants, the majority of which we generated by homologous recombination, and assayed them in the Booze-o-mat to determine their naïve sensitivity to sedation and their tolerance (change in sensitivity upon repeat exposure). Mutants with reproducible phenotypes had their phenotypes rescued with tagged genomic transgenes, and/or phenocopied by nervous system-specific knockdown using RNA interference (RNAi).
Four of the 13 JmjC genes (KDM3, lid, NO66, and HSPBAP1) showed reproducible ethanol (EtOH) sensitivity phenotypes. Some of the phenotypes were observed across doses, for example, the enhanced EtOH sensitivity of KDM3KO and NO66KO, but others were dose dependent, such as the reduced EtOH sensitivity of HSPBAP1KO, or the enhanced EtOH tolerance of NO66KO. These phenotypes were rescued by their respective genomic transgenes in KDM3KO and NO66KO mutants. While we were unable to rescue lidk mutants, knockdown of lid in the nervous system recapitulated the lidk phenotype, as was observed for KDM3KO and NO66KO RNAi-mediated knockdown.
Our study reveals that the Drosophila JmjC-domain histone demethylases Lid, KDM3, NO66, and HSPBAP1 are required for normal EtOH-induced sedation and tolerance. Three of 3 tested of those 4 JmjC genes are required in the nervous system for normal alcohol-induced behavioral responses, suggesting that this gene family is an intriguing avenue for future research.
Alcohol use disorders are accompanied by long-lasting transcriptional changes. Often, these changes are regulated by histone modification, including methylation. A comprehensive survey of all JmjC-domain histone demethylases in Drosophila reveals that a subset of them affect alcohol-induced sedation and rapid tolerance. Furthermore, the ones investigated are required in the nervous system for normal responses to ethanol. Select JmjC-domain histone demethylases are, therefore, participating in the regulation of ethanol-induced behaviors and plasticity.