Functional validation of a finding from a mouse genome-wide association study demonstrates that a mutant allele of Azi2 alters sensitivity to methamphetamine

Methamphetamine is a widely abused psychostimulant. In a previous genome-wide association study (), we identified a locus that influenced the stimulant response to methamphetamine. That locus was also an eQTL for the gene . Based on those findings, we hypothesized that heritable differences in the expression of were causally related to the differential response to methamphetamine. In this study, we created a mutant allele that caused lower expression and enhanced the locomotor response to methamphetamine; however, based on the GWAS findings, we had expected lower to decrease rather than increase the stimulant response to methamphetamine. We then sought to explore the mechanism by which influenced methamphetamine sensitivity. A recent publication had reported that the 3’UTR of mRNA downregulates the expression of , which encodes the dopamine transporter (), which is a key target of methamphetamine. We evaluated the relationship between / 3’UTR and expression in the VTA in the mutant mice and in a new cohort of CFW mice. We did not observe any correlation between and in the VTA in either cohort. However, RNA sequencing confirmed that the mutation altered expression and also revealed a number of potentially important genes and pathways that were regulated by , including the metabotropic glutamate receptor group III pathway and nicotinic acetylcholine receptor signaling pathway. Our results support a role for in methamphetamine sensitivity; however, the exact mechanism does not appear to involve regulation of and thus remains unknown.