Canonical Prolactin Signaling and Global mRNA Expression in the Skin of Holstein Heifers Carrying the SLICK1 Allele of the Prolactin Receptor Gene

The study examined the impact of the SLICK1 allele of the prolactin receptor gene on prolactin signaling and mRNA expression in the skin of Holstein heifers. It involved 11 heifers for immunohistochemistry and 12 for RNA sequencing, comparing slick and nonslick genotypes. Results indicated that slick skin had more hair follicles lacking pSTAT3 immunoreactivity, with no differences in pSTAT1 or pSTAT5. RNA sequencing identified 87 upregulated and 79 downregulated transcripts in slick skin, affecting pathways related to immune regulation, hair growth inhibition, and tissue remodeling. The SLICK1 allele was linked to unique hair and immune characteristics, with upregulated pathways involving IL-17 signaling, leukocyte extravasation, and wound healing. Despite these differences, prolactin, its receptor, and STAT protein expression did not significantly vary between genotypes.