MCT1 and CD147 gene polymorphisms in Standardbred horses

Abstract

Transport of lactate across membranes is facilitated by proton-monocarboxylate transporters (MCT). The most widely distributed isoform is MCT1, which needs an ancillary protein CD147. Studies on erythrocytes have shown that high activity of MCT1 is inherited as the dominant allele and that activity is regulated through CD147. Mutations of human MCT1 have been described that appear to impair lactate transport in muscles and cause exertional rhabdomyolysis. There are no reports of this potential relationship in the horse. To obtain sequences of equine MCT1 and CD147 to examine differences between horses with high and low lactate transport activity in their erythrocytes. Muscle biopsy samples were taken from 3 healthy Standardbred horses and from 7 horses which according to the owners had signs of myopathy after intense exercise. DNA and RNA were isolated and PCR analysis and sequencing performed. Currently, PCR fragments covering 100% of MCT1 and 70% of CD147 coding region are retained and sequence analysis has demonstrated one single nucleotide polymorphism (SNP) in the C-terminal area of MCT1 and one SNP in the extracellular domain of CD147. Both cause an amino acid change. The SNPs found are not related to lactate transport activity in erythrocytes or signs of myopathy. More samples need to be analysed to make conclusions on the significance of the polymorphisms found. Furthermore, full sequence coverage of the coding region of CD147 is needed. The molecular probes produced could be used as tools to study gene regulation of lactate transport.