Hippocampal microRNAs and their Targets based on Transcriptomic Data of Rats that underwent Aerobic Exercise: an in silico study

Abstract

Adult neurogenesis is the continual generation of new neurons from neural stem cells in brain regions such as the subgranular zone (SGZ) of the dentate gyrus in the hippocampus. This genesis is important in learning and memory function, which involve changing the strength of connections between neurons or neuroplasticity. These fundamental and important features of the brain are known to be promoted by exercise, which significantly alters the microenvironment of the hippocampus and increases neurotrophic factors. In recent years, it has been found that microRNAS (miRNAs), 21-23 nucleotide non-coding RNAs that post- transcriptionally suppress mRNA activity, are abundantly expressed in the adult brain and appear to regulate the maintenance of mature neural traits and synaptic plasticity. In this study, 913 target genes of 37 adult rat hippocampal miRNAs were computationally identified from the intersection of three prediction algorithms: TargetScanS, Pictar and miRanda. These were then compared with experimentally derived target genes that had differential expression after voluntary exercise of adult rats from two studies, yielding 25 genes. Using DAVID Functional Annotation Tool, the involvement of these 25 genes in neurogenesis/neuroplasticity was elucidated. It was found from groups of enriched GO terms with enrichment scores >1.3 that 18 out of the 25 target genes were directly involved in neurogenesis/neuroplasticity. Also, the study shed light on the possible role of the temporal expression of miRNAs on neurogenesis/neuroplasticity. The identification and elucidation of the 18 genes can lead to the promotion of good mental health and discovery of treatments for mental illnesses and disorders.