Effects of the bovine SLICK1 mutation in PRLR on sweat gland area and FOXA1 abundance and on global gene expression

The SLICK1 mutation confers thermotolerance to cattle inheriting one or two copies of the gene. Results are unclear as to whether the mutation changes capacity of animals to undergo sweating during heat stress. Accordingly, differences in characteristics of sweat glands between slick and wildtype Holstein heifers was determined. There were no differences in the proportion of skin occupied by sweat glands but sweat glands from slick heifers had higher amounts of immunoreactive FOXA1 than wildtype heifers. FOXA1 is a transcription factor important for sweating. While results do not support the idea that the SLICK1 mutation changes the abundance of sweat glands in skin, it did affect functional properties of sweat glands, as indicated by increased abundance of immunoreactive FOXA1. Overall design: All animal procedures were approved by the University of Florida and University of California Davis Institutional Animal Care and Use Committees. Heifers were genotyped for the SLICK1 mutation in PRLR using either the CLARIFIDE? Plus platform from Zoetis (Parsippany, NJ, USA) or ta KASP-PCR procedure previously described (Sosa et al., 2021). For the purposes of this paper, animals were referred to as SL-/- if they did not inherit a SLICK1 allele (i.e., were wild-type) and SL+/- if they were heterozygous for the SLICK1 allele. The objectives were to determine whether Holstein heifers heterozygous for the SLICK1 mutation (termed SL+/-) have a higher proportion of the dermis of the skin occupied by sweat glands than wildtype heifers without the mutation (termed SL-/-), evaluate whether amounts of immunoreactive FOXA1 in sweat glands differed between SL-/- and SL+/- heifers, and identify differences in skin transcriptome associated with inheritance of the SLICK1 allele.