Identification and characterization of bovine mammary peptide transporters in response to tripeptide and lactogenic hormone treatment

Abstract

Oligopeptide transportation is mediated by the peptide transporter (PepT), which consists of two isoforms, PepT1 and PepT2. Because PepT play essential roles in amino acid metabolism and cell growth, the aim of the present study was to identify these transporters in bovine mammary glands and to analyze the potential functions of these transporters in mammary epithelial cells. Abundance of PepT1 and PepT2 mRNA was successfully measured in both mammary glands and cultured mammary epithelial cells. In addition, the two proteins were examined using immunohistochemistry, immunocytochemistry, and Western blots. The response of mammary epithelial cells to tripeptide and lactogenic hormone treatment was assayed. The PepT mRNA abundance of cultured epithelial cells and secreted protein in the culture medium were increased after tri-peptide substitution and addition of hormones such as insulin, hydrocortisone, and prolactin. The response of mammary epithelial cells to tripeptide and hormone treatments suggests that PepT affects the mammary gland function and increases bovine milk production.