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Gene expression patterns of the four cardiac chambers in the Thoroughbred horse
Charlotte E Edling1, Magdalena Arevalo-Turrubiarte1, Antoine Premont1
1School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Daphne Jackson Road, Guildford, Surrey GU2 7AL, United Kingdom.
Insights
Gene expression in healthy racehorse hearts reveals distinct patterns between chambers. The right atrium shows lower metabolism genes, while the left atrium has higher cardiac conduction genes, impacting equine athletic performance.
Area of Science:
- Equine cardiology
- Molecular biology
- Gene expression analysis
Background:
- Cardiac function is crucial for athletic horse performance.
- Understanding heart gene expression in Thoroughbreds is limited.
- Electrophysiological differences across heart chambers are not fully characterized.
Purpose of the Study:
- To investigate gene expression in the four chambers of healthy Thoroughbred racehorse hearts.
- To identify chamber-specific differences in genes related to cardiac electrophysiology.
- To provide a comprehensive gene expression overview in equine cardiac tissue.
Main Methods:
- Microarray analysis of RNA from left atrium, right atrium, left ventricle, and right ventricle.
- Comparison of gene expression between atrial and ventricular chambers.
- Comparison of gene expression between left and right heart sides.
Main Results:
- Right atrium exhibits significantly lower expression of energy metabolism genes compared to other chambers.
- Left atrium shows higher expression of cardiac conduction genes and lower expression of cardiac morphogenesis genes than ventricles.
- Distinct atrial-ventricular specificity observed for potassium channels (KCNE1, KCNJ2,3,4).
- Calcium regulation genes are more abundant in atria than ventricles.
Conclusions:
- Significant chamber-specific gene expression differences exist in healthy equine hearts.
- These differences, particularly in ion channels and metabolism, may influence cardiac function and performance.
- This study provides foundational gene expression data for equine cardiac research.
Abstract:
Athlete horses' contraction and conduction of the healthy heart influences racing performance. Gene expression patterns in the horse heart are not yet fully investigated. We aim to evaluate the gene expression of the four chambers of the heart overall and with focus on genes involved in the electrophysiology of the heart in Thoroughbred racehorses with no clinical cardiac abnormalities. Tissue was collected from the left atrium (LA), right atrium (RA), left ventricle (LV), and right ventricle (RV). Total RNA was analysed by microarray technique. We compared gene expression in the heart chambers by contrasting atrial against ventricular chambers (chamber related differences), and by contrasting left side to right side (left-to-right related differences). The pathway analyses revealed that RA was characterised by significantly lower expression of genes related to energy derivation and metabolism in comparison to both ventricles and left atria. LA, on the other hand, was characterised by higher expression of genes related to cardiac conduction, and less expression of cardiac morphogenesis, compared to ventricles. The left-to-right related comparisons indicated wider differences between the atria than between the ventricles. Mapping of the genes specifically involved in cardiac conduction and contraction indicated clear chamber related differences. Some potassium channels, KCNE1 and KCNJ2,3 and 4, showed distinct atrial-ventricular specificity and genes involved in calcium regulation were, as a group, more abundant in both atria compared to ventricles. Our results provide a general overview of the gene expression pattern in the healthy racehorse, with particular focus on the cardiac ion channels.
