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

Abstract

BackgroundDigital 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).ResultsThe 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.ConclusionExercise 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.

Comparative Transcriptomic Analyses by RNA-seq to Elucidate Differentially Expressed Genes in the Muscle of Korean Thoroughbred Horses

“…Currently, Illumina technologies are offering higher resolution and are relatively consistent with each other [20]. Nevertheless, the variations in GC content in our sequence data have been seen before [21] and are attributable to dinucleotide fragmentation sites, primer biases, and the protocol followed by the laboratory [22].…”

“…Recent studies have identified PER3 to be upregulated in response to training in skeletal muscle from elite equine athletes [21,37]. It was reported that circadian and metabolic regulation is tightly interlocked at both physiological and molecular levels [52].…”

An Approach to Identify Single Nucleotide Polymorphisms in the Period Circadian Clock 3 (PER3) Gene and Proposed Functional Associations with Exercise Training in a Thoroughbred Horse

“…Signifi- cantly, higher expression of PER3 of horse after exercise supports the role of PER3 in circadian rhythms that may play an important role in sports performance and its importance to achieve the optimal athletic performance [10]. Both RT-PCR and real-time qRT-PCR were performed to clarify the qualitative and quantitative expressions of the genes under study.…”

La génomique: un outil performant pour une gestion intégrée de l'élevage, de l'entraînement et de la santé des chevaux

“…Une étude transcriptomique comparée avant et après 10 mois d'entraînement a été réalisée en 2010 sur le muscle, montrant une diminution de l'expression de 58 gènes, dont le gène codant la myostatine (McGivney et al 2010), une protéine régulant négativement la masse musculaire. Une recherche de polymorphisme par séquen-çage du gène équin, ainsi qu'une analyse d'association pangénomique, ont montré qu'un polymorphisme C>T dans l'intron 1 du gène était associé aux aptitudes sportives : les chevaux C/C sont plus doués pour les courses rapides (sprinters), les individus T/T ont plus d'endurance et gagnent les courses de fond (stayers), alors que les hétérozygotes C/T peuvent être d'excellents milers.…”