Alcohol‐Induced Behaviors Require a Subset of Drosophila JmjC‐Domain Histone Demethylases in the Nervous System

Abstract

Background 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. Methods 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 knock down using RNA interference (RNAi). Results Four of the 13 JmjC genes (KDM3, lid, NO66 and HSPBAP1) showed reproducible ethanol-sensitivity phenotypes. Some of the phenotypes were observed across doses, e.g. the enhanced ethanol-sensitivity of KDM3KO and NO66KO, but others were dose-dependent, such as the reduced ethanol sensitivity of HSPBAP1KO, or the enhanced ethanol 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, knock down of lid in the nervous system recapitulated the lidk phenotype, as was observed for KDM3KO and NO66KO RNAi-mediated knock down. Conclusion Our study reveals that the Drosophila JmjC-domain histone demethylases Lid, KDM3, NO66, and HSPBAP1 are required for normal ethanol-induced sedation and tolerance. Three of three tested of those four 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.

Epigenetic Mechanisms of Alcohol Neuroadaptation: Insights fromDrosophila

“…In the past 2 years, 3 alcohol studies from different Drosophila groups have identified a set of histone-modifying enzymes with direct roles in controlling adaptive alcohol responses. 60 – 62 These findings, reviewed below, have strengthened the link between epigenetic modifications and alcohol-induced neuroadaptations and have solidified the importance of the Drosophila model in elucidating the mechanisms of alcohol addiction.…”

“…In Drosophila , there are at least 13 JmjC-KDMs each with different substrate specificity. 80 In a recent study, Pinzón et al 62 systematically tested the role of all known Drosophila JmjC-KDM in alcohol-induced responses. They focused on 2 main alcohol-related behaviors: innate sensitivity and rapid tolerance.…”

Unraveling the Mechanisms of Behaviors Associated With AUDs Using Flies and Worms

“…To date, over 91 genes in Drosophila and over 50 genes in C. elegans have been identified that regulate EtOH‐induced behaviors (reviewed by Grotewiel and Bettinger, ). The list of genes in Drosophila includes genes involved in the regulation of processes, such as learning and memory, circadian rhythm, innate immune defense, and the blood–brain barrier; on a cellular level, these effects extend to the regulation of the cell cycle, neuronal activity, synaptic function, axonal transport, insulin signaling, immediate early response on transcriptional level, cytoskeleton dynamics, chromosome dynamics, cellular stress responses, and intracellular detoxification of endogenous and xenobiotic substrates (Adhikari et al., ; Choi et al., ; Iacobucci and Gunawardena, ; Morozova et al., ; Parkhurst et al., ; Pinzon et al., , among others; for review, see also Park et al., ).…”

Flying Together: Drosophila as a Tool to Understand the Genetics of Human Alcoholism

“…As a notable alternative to typical transcriptomics, two groups performed ChIP-seq on post-mortem samples to show that, like gene expression, histone methylation is altered in the brains of alcoholics [10,169]. These studies supported later fly research that revealed a role of various histone demethylases in alcohol responses [121]. Given that covalent epigenetic markers are more stable than mRNA, there is great potential for epigenome studies in this context, though these approaches are still in their infancy [10].…”

“…For example, global expression of a protein kinase A (PKA) inhibitor causes sensitivity to alcohol sedation [114], while anatomically limited inhibition causes resistance or sensitivity, depending on the neuroanatomical locus [65,114]. Many studies demonstrate the utility of these Drosophila genetic tools to establish causal roles of various genes in alcohol phenotypes, including many linked to specific cell populations [31,66,101,[115][116][117][118][119][120][121]. The split-Gal4 system permits even further refinement by limiting manipulations to subsets defined by two criteria (e.g., GABAergic neurons in the ellipsoid body) [122], thus allowing investigation into the contribution of neuronal subpopulations or even individual neurons to the development of alcohol abuse disorders ( Figure 1).…”