Transcriptomic hallmarks of bone remodeling revealed by RNA-seq profiling in blood of Arabian horses during racing training regime

Purpose: RNA-seq method was used to identify differentially expressed genes in whole blood involved in bone remodelling during racing training in young Arabian horses.Methods: The comparisons of transcriptomes of whole blood between GI (6 untrained horses) and GII (4 horses after 24 weeks of flat racing training) has been performed. The RNA was isolated using MagMAX™-96 Total RNA Isolation Kit and 400ng were directed to cDNA libraries construction Illumina deep sequencing (75 single-end cycles on Illumina HiScan SQ platform). The bioinformatics analysis include the RSEM and STAR aligner. The raw reads were aligned to the Equus caballus reference genome. Differentially expressed genes were detected by DESeq2.The validation of RNA-seq results were performed by qPCR.Results: After comparison of whole blood transcriptomes from control and trained horses, we identified 1290 training induced genes. Among significant deregulated molecules we recognized twelve genes potentially involved in metabolism of bone (BGLAP, CTSK, TYROBP, PDLIM7, SLC9B2, TWSG1, NOTCH2, IL6ST, VAV3, NFATC1, CLEC5A, TXLNG). Within significantly deregulated pathways one from the most overrepresented was associated with osteoclast differentiation.Conclusions: In the presented study, we identified a panel of DEGs which should be evaluated as candidate biomarkers for bone homeostasis indicators in Arabians performed racetrack. In our results, we pinpointed that intense training has itself effect on immature skeletal system. Thus, further studies are essential to establish biomarkers which could be used in assessment of bone remodelling state during training for race track competition.