Surprisingly, ethanol exposure increased expression of both GIRK2 immunoreactivity and KCNJ6 mRNA. Following 7 days of IEE, GIRK2 puncta in the AF group increased to levels significantly higher than the UN group (Fig. 5B). Similarly, KCNJ6 mRNA levels were shown to be increased by scRNAseq results (Fig. 1C) and FISH analysis (Fig. 5J). While previous studies identified a binding site for ethanol in a defined pocket of GIRK2 [53], suggesting that it could affect protein stabilization, this could not explain the increased mRNA level. There is no indication that ethanol or KCNJ6 haplotype altered translocation of KCNJ6 mRNA to neuronal processes (Fig. 5J.d, e). Ethanol has been found to affect microRNA expression patterns that regulate mRNA [49, 54–59]. It is intriguing to speculate that ethanol might increase expression of GIRK2 through this type of mechanism, with polymorphisms in the 3′UTR serving as the modulator.
