Multi‐animal‐model study reveals mutations in neural plasticity and nociception genes linked to excessive alcohol drinking

Abstract

BackgroundThe basis for familial alcohol use disorder (AUD) remains an enigma due to various biological and societal confounds. The present study used three of the most adopted and documented rat models, combining the alcohol‐preferring/non‐alcohol‐preferring (P/NP) lines and high alcohol‐drinking/low alcohol‐drinking (HAD/LAD) replicated lines, of AUD as examined through the lens of whole genomic analyses.MethodsWe used complete genome sequencing of the P/NP lines and previously published sequences of the HAD/LAD replicates to enhance the discovery of variants associated with AUD and to remove confounding with genetic background and random genetic drift. Specifically, we used high‐order statistical methods to search for genetic variants whose frequency changes in whole sets of gene ontologies corresponded with phenotypic changes in the direction of selection, that is, ethanol‐drinking preference.ResultsOur first finding was that in addition to variants causing translational changes, the principal genetic changes associated with drinking predisposition were silent mutations and mutations in the 3′ untranslated regions (3′UTR) of genes. Neither of these types of mutations alters the amino acid sequence of the translated protein but they influence both the rate and conformation of gene transcription, including its stability and posttranslational events that alter gene efficacy. This finding argues for refocusing human genomic studies on changes in gene efficacy. Among the key ontologies identified were the central genes associated with the Na+ voltage–gated channels of neurons and glia (including the Scn1a, Scn2a, Scn2b, Scn3a, Scn7a, and Scn9a subtypes) and excitatory glutamatergic secretion (including Grm2 and Myo6), both of which are essential in neuroplasticity. In addition, we identified “Nociception or Sensory Perception of Pain,” which contained variants in nociception (Arrb1, Ccl3, Ephb1) and enlist sodium (Scn1a, Scn2a, Scn2b, Scn3a, Scn7a), pain activation (Scn9a), and potassium channel (Kcna1) genes.ConclusionThe multi‐model analyses used herein reduced the confounding effects of random drift and the “founders” genetic background. The most differentiated bidirectionally selected genes across all three animal models were Scn9a, Scn1a, and Kcna, all of which are annotated in the nociception ontology. The complexity of neuroplasticity and nociception adds strength to the hypothesis that neuroplasticity and pain (physical or psychological) are prominent phenotypes genetically linked to the development of AUD.

Identification of ethanol analgesia quantitative trait loci and candidate genes in BXD recombinant inbred mouse lines

“…In the field of alcohol research, Myo6 has been shown to be downregulated in myelin-forming oligodendrocyte cells in mouse cerebellum following chronic-plus-binge ethanol exposure [52]. A synonymous single nucleotide variant in Myo6 was one of only 12 loci in the rat genome significantly associated with ethanol consumption in the alcohol-preferring (P) rodent model and the high-alcohol drinking (HAD) replicated lines[53]. Given the recent findings in model organism and human alcohol literature, the genomic position in the novel Etadq1 ethanol analgesia QTL, the correlation between midbrain Myo6 expression and ethanol-mediated antinociception, and the significant cis -eQTL regulating expression in PFC, we hypothesize a role for Myo6 in regulating ethanol analgesia in mice.…”