Significance of KLK7 expression, polymorphisms, and function in sheep horn growth

Our results demonstrate that KLK7 was highly expressed in soft horn and skin tissues, and its expression was significantly higher in small-horned sheep than it was in large-horned sheep, suggesting that KLK7 may have an inhibitory effect on horn growth. By comparing the amino acid sequence of KLK7 with KLK7 sequences in other species, we discovered eight amino acids at specific positions in the KLK7 protein sequence that may have regulatory functions in determining the size of horns in ruminant animals. Thirteen SNPs with F-statistic value (Fst) > 0.15 were identified. By integrating RNA-Seq and WGS data, we discovered two SNPs (g.56695395 T > C and g.56695484A > C) with allele specific expression between the large- and small-horned sheep. The two SNPs were validated and were found to have significantly different (P < 0.05) effects on horn length. Our findings suggest a strong association between KLK7 and sheep horn length, indicating the potential role of KLK7 in inhibiting horn growth and providing novel insights into the functionality of KLK7.