Sex-Specific Expression of Non-Coding RNA Fragments in Frontal Cortex, Hippocampus and Cerebellum of Rats.

Non-coding RNA fragments (ncRFs) are processed from various non-coding RNAs (ncRNAs), with the most abundant being those produced from tRNAs. ncRFs were reported in many animal and plant species. Many ncRFs exhibit tissue specificity or/and are affected by stress. There is, however, only a handful of reports that describe differential expression of ncRFs in the brain regions. In this work, we analyzed the abundance of ncRFs processed from four major ncRNAs, including tRNA (tRFs), snoRNA (snoRFs), snRNA (snRFs), and rRNA (rRFs) in the frontal cortex (FC), hippocampus (HIP), and cerebellum (CER) of male and female rats. We found brain-specific and sex-specific differences. Reads mapping to lincRNAs were significantly larger in CER as compared to HIP and CER, while those mapping to snRNAs and tRNA were smaller in HIP than in FC and CER. tRF reads were the most abundant among all ncRF reads, and FC had more reads than HIP and CER. Reads mapping to antisense ncRNAs were significantly larger in females than in males in FC. Additionally, males consistently had more tRF, snRF, and snoRF reads in all brain regions. rRFs were more abundant in males in FC and females in HIP. Several tRFs were significantly underrepresented, including tRF-ValCAC, tRF-ValACC, and tRF-LysCTT in all brain regions. We also found brain- and sex-specific differences in the number of brain function-related mRNA targets. To summarize, we found sex-specific differences in the expression of several ncRNA fragments in various brain regions of healthy rats.