Alternative polyadenylation in the brain is altered by chronic ethanol exposure in a sex- and cell type-specific manner

Abstract

Alternative polyadenylation (APA) is a common posttranscriptional mechanism to regulate gene expression. APA generates mRNAs with varying lengths of 3' UTRs or transcripts that encode distinct protein carboxy-terminal ends. APA is especially important in neurons, where different mRNA variants are often asymmetrically localized to dendrites and axons, and can be locally translated into proteins. Local protein synthesis is crucial for axon guidance, synaptic plasticity, and learning and memory, key processes associated with the development of alcohol use disorder (AUD). We investigated the role of APA in AUD using a mouse model of alcohol dependence characterized by increased voluntary drinking after chronic intermittent ethanol (CIE) exposure. We examined APA during protracted withdrawal from alcohol in three brain regions of male and female mice. Our analyses revealed hundreds of genes undergoing APA in males, but substantially fewer in females, suggesting sex-specific effects of CIE on APA. Notably, male and female mice displayed distinct APA signatures. APA genes were different from differentially expressed genes (DEGs), suggesting that these molecular processes are regulated independently. We also determined that the expression of APA genes was associated with neurons, while DEGs were associated with non-neuronal cells. Many of the APA genes were involved in synaptic integrity, neuroplasticity, and neuronal maintenance, which was consistent with their enrichment in neurons. Our study suggests that APA is a crucial sex- and cell type-specific mechanism in AUD with the potential to influence localized neuronal protein expression during protracted withdrawal and to modify alcohol consumption behavior. HIGHLIGHTSO_LIChronic ethanol exposure in mice results in profound changes of APA genes in brain. C_LIO_LICommonly regulated cleavage and polyadenylation sites and genes were identified in male but not in female mice. C_LIO_LIThere was a minimal overlap between APA and differentially expressed genes (DEGs). C_LIO_LIAPA genes were primarily associated with neurons, whereas DEGs were associated with non-neuronal cells. C_LI