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Since ancient days, domestic horses have been closely associated with human civilization. Today, horse racing is an important industry. Various genes involved in energy production and muscle contraction are differentially regulated during a race. Among them, creatine kinase (CK) is well known for its regulation of energy preservation in animal cells. CK is an iso-enzyme, encoded by different genes and expressed in skeletal muscle, heart, brain and leucocytes. We confirmed that the expression of CK-M significantly increased in the blood after a 30 minute exercise period, while no considerable change was observed in skeletal muscle. Analysis of various tissues showed an ubiquitous expression of the CK-M gene in the horse; CK-M mRNA expression was predominant in the skeletal muscle and the cardiac muscle compared to other tissues. An evolutionary study by synonymous and non-synonymous single nucleotide polymorphism ratio of CK-M gene revealed a positive selection that was conserved in the horse. More studies are warranted in order to develop the expression of CK-M gene as a biomarker in blood of thoroughbred horses.

The purpose of this study was to investigate the alternative splicing in equine cordon-bleu WH2 repeat protein-like 1 (COBLL1) gene that was identified in horse muscle and blood leukocytes, and to predict functional consequences of alternative splicing by bioinformatics analysis. In a previous study, RNA-seq analysis predicted the presence of alternative spliced isoforms of equine COBLL1, namely COBLL1a as a long form and COBLL1b as a short form. In this study, we validated two isoforms of COBLL1 transcripts in horse tissues by the real-time polymerase chain reaction, and cloned them for Sanger sequencing. The sequencing results showed that the alternative splicing occurs at exon 9. Prediction of protein structure of these isoforms revealed three putative phosphorylation sites at the amino acid sequences encoded in exon 9, which is deleted in COBLL1b. In expression analysis, it was found that COBLL1b was expressed ubiquitously and equivalently in all the analyzed tissues, whereas COBLL1a showed strong expression in kidney, spinal cord and lung, moderate expression in heart and skeletal muscle, and low expression in thyroid and colon. In muscle, both COBLL1a and COBLL1b expression decreased after exercise. It is assumed that the regulation of COBLL1 expression may be important for regulating glucose level or switching of energy source, possibly through an insulin signaling pathway, in muscle after exercise. Further study is warranted to reveal the functional importance of COBLL1 on athletic performance in race horses.

The purpose of this study was to investigate the alternative splicing in equine cordon-bleu WH2 repeat protein-like 1 (COBLL1) gene that was identified in horse muscle and blood leukocytes, and to predict functional consequences of alternative splicing by bioinformatics analysis. In a previous study, RNA-seq analysis predicted the presence of alternative spliced isoforms of equine COBLL1, namely COBLL1a as a long form and COBLL1b as a short form. In this study, we validated two isoforms of COBLL1 transcripts in horse tissues by the real-time polymerase chain reaction, and cloned them for Sanger sequencing. The sequencing results showed that the alternative splicing occurs at exon 9. Prediction of protein structure of these isoforms revealed three putative phosphorylation sites at the amino acid sequences encoded in exon 9, which is deleted in COBLL1b. In expression analysis, it was found that COBLL1b was expressed ubiquitously and equivalently in all the analyzed tissues, whereas COBLL1a showed strong expression in kidney, spinal cord and lung, moderate expression in heart and skeletal muscle, and low expression in thyroid and colon. In muscle, both COBLL1a and COBLL1b expression decreased after exercise. It is assumed that the regulation of COBLL1 expression may be important for regulating glucose level or switching of energy source, possibly through an insulin signaling pathway, in muscle after exercise. Further study is warranted to reveal the functional importance of COBLL1 on athletic performance in race horses. [ABSTRACT FROM AUTHOR]