title: Alcohol-dose-dependent DNA methylation and expression in the nucleus accumbens identifies coordinated regulation of synaptic genes.
abstract: Alterations in DNA methylation have been associated with alcohol exposure and proposed to contribute to continued alcohol use; however, the molecular mechanisms involved remain obscure. We investigated the escalating effects of alcohol use on DNA methylation, gene expression and predicted neural effects in the nucleus accumbens of rhesus macaques that self-administered 4% alcohol for over 12 months. Using an exploratory approach to identify CpG-rich regions, followed by bisulfite sequencing, the methylation levels of 2.7 million CpGs were compared between seven low-binge drinkers and nine heavy-very heavy drinking subjects. We identified 17 significant differential methylation regions (DMRs), including 14 with methylation levels that were correlated with average daily alcohol consumption. The size of the DMRs ranged from 29 to 158 bp (mean=63.7), included 4-19 CpGs per DMR (mean=8.06) and spanned a range of average methylation values from 5 to 34%. Eight of the DMRs mapped to genes implicated in modulating synaptic plasticity. Six of the synaptic genes have not previously been linked to alcohol use. Validation studies of these eight DMRs using bisulfite amplicon sequencing and an expanded set of 30 subjects confirmed the significant alcohol-dose-associated methylation of the DMRs. Expression analysis of three of the DMR-associated genes, LRP5, GPR39 and JAKMIP1, revealed significant correlations between DMR methylation and whole-gene or alternative transcript expression, supporting a functional role in regulating gene expression. Together, these studies suggest that alcohol-associated synaptic remodeling may be regulated and coordinated at the level of DNA methylation.
authors.affiliation: Department of Neurosciences, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA.
authors.forename: R
authors.initials: R
authors.lastname: Cervera-Juanes
authors.affiliation: Department of Neurosciences, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Wilhelm
authors.affiliation: Department of Public Health and Preventive Medicine, Oregon Health and Science University, Portland, OR, USA.
authors.forename: B
authors.initials: B
authors.lastname: Park
authors.affiliation: Department of Neurosciences, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Grant
authors.affiliation: Department of Neurosciences, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA.
authors.forename: B
authors.identifier: 0000-0002-6992-3538
authors.initials: B
authors.lastname: Ferguson
mesh_terms: D000437:Alcoholism / Q000235:genetics; D000818:Animals; D063425:Binge Drinking / Q000235:genetics; D016022:Case-Control Studies; D002492:Central Nervous System Depressants / Q000008:administration & dosage / Q000494:pharmacology*; D018899:CpG Islands / Q000187:drug effects / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000235:genetics; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008253:Macaca mulatta; D008297:Male; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012646:Self Administration; D017423:Sequence Analysis, RNA; D013569:Synapses / Q000378:metabolism
chemical_list: D002492:Central Nervous System Depressants; D000431:Ethanol