Sequence variations and two levels of MCT1 and CD147 expression in red blood cells and gluteus muscle of horses.

This study examined whether genetic variations are tied to the different levels of expression of two transport proteins MCT1 and CD147 in horses’ red blood cells and muscles. The researchers discovered that certain sequence changes are linked to lower levels of CD147, but these variations don’t explain the bimodal expression of this protein. Moreover, the levels of MCT1 and CD147 mRNA correlated with CD147 expression level, suggesting that this bimodal expression might be regulated at the level of transcription.

Study Setting and Background

• The transport proteins MCT1 and CD147 are responsible for lactate transport in most mammals, including horses. These proteins exhibit a bimodal expression in horses – high in about 70% and low in approximately 30% of the population.
• The researchers endeavored to explore whether genetic variations could explain this bimodality in protein expression.

Methodology

• The researchers collected samples of blood and cremaster muscle from 24 horses during castrations. Additional gluteus muscle samples were collected from 15 Standardbreds, seven of which were known to express low CD147 levels in their red blood cells.
• The cDNA of MCT1 and CD147, along with a promoter region of CD147, were sequenced to look for genetic variations.
• The protein expressions of MCT1 and CD147 in red blood cell and muscle membranes were measured using Western blot technique, and mRNA levels in muscles were determined via qPCR.

Findings

• MCT1 and CD147 were expressed in 20 of the castrated horses, only traces were found in the remaining four.
• The researchers detected no link between the identified sequence variations in MCT1 and its protein expression. However, two specific heterozygous single nucleotide polymorphisms (SNPs) in CD147 were associated with a low expression of this protein. Also, a particular mutation in CD147 was associated with low expression of both MCT1 and CD147.
• Low MCT1 and CD147 mRNA levels were discovered in those Standardbreds with low CD147 expression in their red blood cells.
• Notably, although sequence variations appear to affect the expression level of CD147, they do not explain the protein’s bimodal expression. This indicates that other factors may be involved in regulating this phenomenon.

Conclusion

• The study concludes that the bimodal expression of MCT1 and CD147 may be regulated at the transcriptional level, given the association between mRNA levels and protein expression.
• While sequence variations are related to expression rates of CD147, there are yet unexplained factors behind the protein’s bimodal expression. This opens up a path for further research on the regulation of these important transport proteins.