Molecular Characterization and Expression Analysis of Equine Vascular Endothelial Growth Factor Alpha (VEGFα) Gene in Horse (Equus caballus)

The objective of this study was to determine the molecular characteristics of the horse vascular endothelial growth factor alpha gene ($VEGF{\alpha}$) by constructing a phylogenetic tree, and to investigate gene expression profiles in tissues and blood leukocytes after exercise for development of suitable biomarkers. Using published amino acid sequences of other vertebrate species (human, chimpanzee, mouse, rat, cow, pig, chicken and dog), we constructed a phylogenetic tree which showed that equine $VEGF{\alpha}$ belonged to the same clade of the pig $VEGF{\alpha}$. Analysis for synonymous (Ks) and non-synonymous substitution ratios (Ka) revealed that the horse $VEGF{\alpha}$ underwent positive selection. RNA was extracted from blood samples before and after exercise and different tissue samples of three horses. Expression analyses using reverse transcription-polymerase chain reaction (RT-PCR) and quantitative-polymerase chain reaction (qPCR) showed ubiquitous expression of $VEGF{\alpha}$ mRNA in skeletal muscle, kidney, thyroid, lung, appendix, colon, spinal cord, and heart tissues. Analysis of differential expression of $VEGF{\alpha}$ gene in blood leukocytes after exercise indicated a unimodal pattern. These results will be useful in developing biomarkers that can predict the recovery capacity of racing horses.