Landscape of rat microRNA BodyMap across 11 organs, four ages, and two sexes

The rat has been used extensively as a model system for biological studies. However, its microRNA (miRNA) transcriptome has not been well established. Here, we constructed a comprehensive rat miRNA BodyMap based on miRNA-seq of 320 samples from 11 organs of both sexes of juvenile, adolescent, adult, and aged Fischer 344 rats. We quantified the expression profiles of 993 rat miRNAs, including 268 novel miRNA candidates. A large number of miRNAs showed organ-specific, age-dependent, or sex-specific expression patterns. Particularly, brain exhibited the strongest organ-enriched expression patterns, and testis showed the most strikingly age-dependent expression patterns. Interestingly, the expression levels of two clusters of miRNAs were highly correlated with those of mRNAs and were highly age dependent. The miRNA dataset along with previously reported mRNA data from the same set of samples represents a unique resource to improve understanding of rat transcriptome and subsequently better utilize rats for biomarker discovery.