Integrative analysis of sex-specific microRNA networks following stress in mouse nucleus accumbens

Adult women are twice as likely as men to suffer from affective and anxiety disorders, although the mechanisms underlying heightened female stress susceptibility are incompletely understood. Recent findings in mouse Nucleus Accumbens (NAc) suggest a role for DNA methyltransferase-driven sex differences in genome-wide transcriptional profiles. However, the role of another epigenetic process—microRNA (miR) regulation—has yet to be explored. We exposed male and female mice to Subchronic Variable Stress (SCVS), a stress paradigm that produces depression-like behavior in female, but not male, mice, and performed next-generation mRNA and miR sequencing on NAc tissue. We applied a combination of differential expression, miR-mRNA network and functional enrichment analyses to characterize the transcriptional and post-transcriptional landscape of sex differences in NAc stress response. We find that male and female mice exhibit largely non-overlapping miR and mRNA profiles following SCVS. The two sexes also show enrichment of different molecular pathways and functions. Collectively, our results suggest that males and females mount fundamentally different transcriptional and post-transcriptional responses to SCVS and engage sex-specific molecular processes following stress. These findings have implications for the pathophysiology and treatment of stress-related disorders in women. miR and mRNA profiles in male and female mice exposed to SCVS were generated to identify sex differences in transcriptional and post-transcriptional stress response. Profiles were generated from 3 libraries per sex/stress condition (male control, male stressed, female control, female stressed), totaling 12 libraries for both the miR and mRNA analyses. Libraries for miR and mRNA sequencing were generated from separate size-enriched fractions of RNA isolated from nucleus accumbens (NAc) of 5 pooled samples per library. All female pools contained NAc from females in estrus or proestrus to control for the female estrous cycle.