Single Nucleotide Polymorphism in Interleukin-6 and Interleukin-8 Genes of Equines

In equines, muscle exercise highly affects the expression of genes which are associated with secretion of cytokines. Myokines are the group of cytokines that are produced by skeletal muscles during exercise. Interleukin-6 (IL-6) and Interleukin-8 (IL-8) are among such myokines. This study was therefore taken up in 42 animals of Marwari, Kathiawari, Manipuri and Zanskari horses; and Poitou and Halari donkeys to find out the Single Nucleotide Polymorphisms (SNPs) in the IL-6 and IL-8 genes. Sequence analysis of exon 2 of IL-6 gene revealed an intronic SNP (C>T) at position Equcab3.0:4:54607583 in Poitou donkey. No SNP was detected in the equines covered in the study for IL-6 exon 5, exon 6 and their flanking sequences. However, in exon 1 of the IL-8 gene of all 4 horse breeds and 2 donkey breeds, a non-synonymous SNP (G > C) leading to a change in amino acid from leucine (L) to phenylalanine (F) (p. Leu10> p. Phe10) was observed at position EquCab3.0:3:63720817. Another nucleotide substitution was T>C in the intron 1-2 of IL-8 gene in all equids studied at position EquCab3.0:3:63720770. In addition to above two substitutions, in the 5' UTR of IL-8 gene in Poitou donkey, in place of guanosine (G), heterozygous condition S (C/G) was observed at position EquCab3.0:3: 63720883. This paper presents four SNPs with one non-synonymous SNP leading to a change in IL-8 protein sequence in equines.