Characterization of the equine skeletal muscle transcriptome identifies novel functional responses to exercise training

BMC Genomics (Impact Factor: 3.99). 01/2010;
Source: DOAJ




Digital gene expression profiling was used to characterize the assembly of genes expressed in equine skeletal muscle and to identify the subset of genes that were differentially expressed following a ten-month period of exercise training. The study cohort comprised seven Thoroughbred racehorses from a single training yard. Skeletal muscle biopsies were collected at rest from the gluteus medius at two time points: T1 - untrained, (9 ± 0.5 months old) and T2 - trained (20 ± 0.7 months old).


The most abundant mRNA transcripts in the muscle transcriptome were those involved in muscle contraction, aerobic respiration and mitochondrial function. A previously unreported over-representation of genes related to RNA processing, the stress response and proteolysis was observed. Following training 92 tags were differentially expressed of which 74 were annotated. Sixteen genes showed increased expression, including the mitochondrial genes ACADVL , MRPS21 and SLC25A29 encoded by the nuclear genome. Among the 58 genes with decreased expression, MSTN , a negative regulator of muscle growth, had the greatest decrease.

Functional analysis of all expressed genes using FatiScan revealed an asymmetric distribution of 482 Gene Ontology (GO) groups and 18 KEGG pathways. Functional groups displaying highly significant ( P < 0.0001) increased expression included mitochondrion, oxidative phosphorylation and fatty acid metabolism while functional groups with decreased expression were mainly associated with structural genes and included the sarcoplasm, laminin complex and cytoskeleton.


Exercise training in Thoroughbred racehorses results in coordinate changes in the gene expression of functional groups of genes related to metabolism, oxidative phosphorylation and muscle structure.

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    • "The first analysis using next-generation technology in regards to changes in the gene expression profiles during exercise adaptation was applied in Thoroughbred horses. McGivney et al. (2010) confirmed the differential expression of 92 transcripts in equine muscle tissues before and after longterm exercise. Sixteen genes were upregulated in response to increase of physical activity, including some mitochondrial genes (ACADVL), troponin T type 3 (TNNT3), SLC25A29, and genes coding the period homology of 2 and 3 proteins (PER2, PER3). "
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    ABSTRACT: RNA sequencing (RNA-seq) by next-generation technology is a powerful tool which creates new possibilities in whole-transcriptome analysis. In recent years, with the use of the RNA-seq method, several studies expanded transcriptional gene profiles to understand interactions between genotype and phenotype, supremely contributing to the field of equine biology. To date, in horses, massive parallel sequencing of cDNA has been successfully used to identify and quantify mRNA levels in several normal tissues, as well as to annotate genes. Moreover, the RNA-seq method has been applied to identify the genetic basis of several diseases or to investigate organism adaptation processes to the training conditions. The use of the RNA-seq approach has also confirmed that horses can be useful as a large animal model for human disease, especially in the field of immune response. The presented review summarizes the achievements of profiling gene expression in horses (Equus caballus).
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    • "The beneficial effects of chronic training may be severely disrupted by major effort, although this effect is overcome in <24 h in well-trained subjects, suggesting that specific training may increase adaptive responses to exercise (Lira et al., 2009; Capomaccio et al., 2010). Previous studies have shown that repeated bouts of exercise can lead to new basal levels of gene expression in resting tissues (McGivney et al., 2010; Capomaccio et al., 2011) and horses seem to develop strong adaptation mechanisms capable of maintaining an anti-inflammatory body environment at rest (Capomaccio et al., 2011). An interesting outcome from this study result was that all of the tested genes (with the exception of CXCL2 and IL8) were expressed at significantly higher levels in the athletic horses compared to sedentary animals (Fig. 1A). "
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