Molecular characterisation, genetic variability and detection of a functional polymorphism influencing the promoter activity of OXT gene in goat and sheep

The purpose of the study described in this Research Communication was to report the full characterisation of the goat and sheep oxytocin-neurophysin I gene (OXT), their promoters and amino acid sequences. Using the genomic DNA as template, we sequenced and compared the whole OXT gene (3 exons), plus 958/960 nucleotides at the 5' flanking region and 478/477 nucleotides at the 3' flanking region, in 46 sheep and 24 goats belonging to different breeds/genetic types reared in Italy, Greece and Germany. The comparison of the obtained sequences showed a high degree of genetic variability at these loci. In particular, we focused on the SNP g.438T > C as possible example of trans-specific polymorphism. This SNP alters a putative binding site of the transcription factor Oct-1. The set-up of a luciferase assay confirmed that the C variant of this SNP negatively affects the promoter activity of the sheep OXT gene. The results of this study suggest that the SNP g.438T > C might be useful to promote association studies with traits/physiological processes controlled by this hormone.