microRNA-sequencing of inbred mouse strain hippocampus and frontal cortex

Purpose: We carried out small RNA sequencing to determine miRNA expression patterns of hippocampus and frontal cortex in six inbred mouse strains. We analyzed miRNA expression levels, isomiR distribution and miRNA editing events. Methods: We constructed small RNA libraries starting from the total RNA extracted from the hippocampus and frontal cortex of three animals per strain. The sequencing was carried out using Illumina HiSeq2000 (single-end). The sequence reads that passed quality filters were mapped to the mouse genome (mm10) and to known miRNAs (miRBase v21) using miRDeep2, SeqBuster, and sRNAbench, to obtain miRNA and isomiR expression levels and to predict novel miRNAs. Genome alignments were analysed for miRNA editing using FreeBayes. Results: We detected significant miRNA and isomiR expression level differences between the strains and brain regions. Most of the miRNA loci produced a number of isomiRs. Some miRNAs were consistently edited with a pattern that matches the activity of known RNA editing enzymes. Overall design: Small RNA sequencing of hippocampus and frontal cortex of 6 inbred mouse strains using Illumina HiSeq2000