Chemerin is a novel regulator of lactogenesis in bovine mammary epithelial cells

Chemerin is a chemoattractant cytokine (chemokine) produced by adipocytes and hepatocytes; it regulates insulin sensitivity and adipocyte differentiation. The objective of this study was to investigate the effect of chemerin on the expression of genes related to lactogenesis and the regulators of chemerin signaling in a bovine mammary epithelial cell line (MAC-T). Two types of chemerin receptors, chemokine like-receptor 1 (CMKLR1) and chemokine (C-C motif) receptor-like 2 (CCRL2), were detected in cultured MAC-T cells, whereas chemerin was not detected. G protein-coupled receptor 1 (GPR1), another receptor of chemerin, was undetectable in MAC-T cells. Chemerin upregulated transcript expression of CMKLR1, CCRL2, and genes associated with fatty acid synthesis, glucose uptake, insulin signaling, and casein synthesis in MAC-T cells. Lactogenic hormones (insulin, growth hormone, and prolactin) downregulated the expression of CMKLR1 in MAC-T cells. Adiponectin suppressed CMKLR1 expression. TNF-α suppressed CMKLR1, but induced CCRL2 expression. These data suggest chemerin is a novel regulator of lactogenesis via its own receptor in bovine mammary epithelial cells.