Sequence analysis and expression profiling of the equine ACTN3 gene during exercise in Arabian horses.

The research investigates the functionality and expression levels of the ACTN3 gene in Arabian horses, which is associated with muscle contraction and the metabolic process during exercise. High levels of this gene were found in untrained horses, while low expression levels were found in horses fully adapted to racing. Through structural analysis, 14 polymorphisms were identified, two of which may affect gene expression.

About the ACTN3 gene

• The ACTN3 gene is responsible for producing α-actinin-3, a protein that resides in the skeletal muscle of the body.
• This protein plays a crucial role in facilitating muscle contraction, by anchoring the myofibrillar actin filaments.
• The α-actinin-3 also engages in metabolism by cross-linking glycogen phosphorylase (GP), an enzyme essential for glycogen metabolism.

The Study

• The central aim of this research was to determine the expression levels of the ACTN3 gene in the gluteus medius muscle of Arabian horses and correlate it with their training intensity.
• In addition to the expression analysis, the researchers also did a structural analysis of the gene to detect any polymorphisms that may contribute to racing performance.
• The research found a significant decrease in the expression of ACTN3 in the skeletal muscle during the training periods for flat-racing, with expression varying based on the intensity of exercise.
• The highest gene expression was found in untrained horses, while the lowest, was identified at the end of the racing season, where the horses are fully adapted to the racing workload.

ACTN3 Gene Polymorphisms

• In their investigation of the ACTN3 structure, the team discovered 14 polymorphisms. These were found in various areas: the promoter region, the 5’UTR, exons, and introns.
• Two polymorphisms in particular (a novel c.2334C>T – splice variant and the g.1104G>A polymorphism in the promoter region) are believed to potentially affect gene expression.

Conclusions and Future Directions

• The study establishes the crucial role of the ACTN3 gene in Arabian horses’ physiological adaptation to exertion.
• Given the significance of its role and known variable expression, further studies are suggested to verify the ACTN3 gene’s potential as a genetic marker to determine exercise performance in not just Arabian horses, but other horse breeds as well.