Epigenetic control of exercise adaptations in the equine athlete: Current evidence and future directions

Abstract

Horses (Equus ferus caballus) have evolved over the past 300 years in response to man‐made selection for particular athletic traits. Some of the selected traits were selected based on the size and horses’ muscular power (eg Clydesdales), whereas other breeds were bred for peak running performance (eg Thoroughbred and Arabian). Although the physiological changes and some of the cellular adaptations responsible for athletic potential of horses have been identified, the molecular mechanisms are only just beginning to be comprehensively investigated. The purpose of this review was to outline and discuss the current understanding of the molecular mechanisms underpinning the athletic performance and cardiorespiratory fitness in athletic breeds of horses. A brief review of the biology of epigenetics is provided, including discussion on DNA methylation, histone modifications and small RNAs, followed by a summary and critical review of the current work on the exercise‐induced epigenetic and transcriptional changes in horses. Important unanswered questions and currently unexplored areas that deserve attention are highlighted. Finally, a rationale for the analysis of epigenetic modifications in the context with exercise‐related traits and ailments associated with athletic breeds of horses is outlined in order to help guide future research.

Assessment and Distribution of Runs of Homozygosity in Horse Breeds Representing Different Utility Types

“…The next identified gene, DNMT1 , encoded DNA (cytosine-5)-methyltransferase 1 and can be strongly related to exercise adaptation. The rates of DNA methylation and epigenetic modification were also recognized as critical adjustments to effort in equine athletes [ 52 ]. What is more, exercise-induced DNA methylation changes allow for optimal adaptation to exercise [ 53 ].…”

The Emerging Role of Hypoxic Training for the Equine Athlete

“…The transient changes in transcription and expression of mRNA for metabolic genes have been examined following a single bout or session of exercise [20,21] and the effects on the concentration of the proteins [17,22,23]. The role of exercise-induced epigenetic modifications in exercise adaptations is also beginning to emerge in the equine field [24]. In addition to the training stimuli, a stimulus in the form of hypoxia may well provide additional training stress and greater physiological adaptations.…”

Equine Endothelial Cells Show Pro-Angiogenic Behaviours in Response to Fibroblast Growth Factor 2 but Not Vascular Endothelial Growth Factor A

“…This process is important for normal tissue maintenance and repair and is disordered in disease states where endothelial dysfunction is prevalent [ 1 ]. Despite growing interest in the horse as a large animal model for a range of diseases, including various musculoskeletal conditions [ 2 , 3 , 4 , 5 ], neoplasia [ 6 ], cardiac disease [ 7 ], retinal disease [ 8 ], pulmonary conditions [ 9 , 10 ], endocrinopathies [ 11 ], and Raynaud’s disease [ 12 ], and the recognition that this species has utility for investigating wound healing [ 13 ], regenerative medicine [ 14 , 15 , 16 ], reproductive [ 17 ], immunological [ 18 ], and stem cell [ 16 ] research, alongside the horse’s extreme athletic ability [ 19 ], equine EC biology has received minimal scientific attention.…”