Analyses of exercise transcriptome: a next generation sequencing approach

Even if horse is a natural athlete, exercise exerts a great effect on its physiology. It has been hypothesized that syndromes developed in athlete subjected to heavy training (i.e. overtraining), are based on a so-called immune system derangement. The purpose of this study is to analyze the transcriptional response of horses to endurance races through RNAseq with SOLiD technology; sequencing was performed on PBMCs samples of two top-level horses with a time course strategy: at rest (t1) and immediately after the race (t2). After filtering, reads were mapped on to the horse genome (EquCab2.0) allowing at least 90% of identity, producing 102 million alignments. Genome coverage distribution was calculated at exonic, intronic and intergenic level; in particular, with respect to the unique mapping, we observed a 7% shift from intronic to exonic regions in the time course comparison, possibly indicating a poor annotation or a peculiar transcription direction. Another interesting finding, highlighted with the directional sequencing, is the strong antisense transcription increasing after the effort in all genomic sectors (exons, introns and intergenic regions) as well as the considerable induction of repetitive elements, in particular LINEs. For what concerns the resolution of the experiment in term of differentially expressed genes, 740 genes are down-regulated and 1424 up regulated in the t1 vs t2 comparison. These results highlight the complexity of mammalian transcription under stressing condition that could induce a regulation trough repeat and antisense transcriptome profile and an enhancement of the alternative splicing activity. Funded by InnovaGen