Short-chain fatty acid signaling pathways in bovine mammary epithelial cells

GPR41 and 43 have recently been identified as G-protein-coupled cell-surface receptors for short-chain fatty acids (SCFAs). Bovine orthologs of GPR41 and 43 (bGPR41 and 43) mRNA were detected by RT-PCR in cloned bovine mammary epithelial cells (bMEC) and various lactation stages of bovine mammary gland. Acetate and propionate caused an increase in intracellular Ca²⁺ concentrations in these cells that was blocked by the treatment with pertussis toxin (PTX). SCFAs significantly reduced forskolin-induced cAMP concentrations in these cells. The phosphorylation of mitogen-activated protein kinase (MAPK) p38 was selectively increased by SCFAs. The downstream substrate heat shock protein 27 (HSP27) was also phosphorylated by SCFAs at Ser-78 and -82, but not -15. These results suggest that bGPR41 mainly, but not bGPR43, mediate SCFA signaling in mammary epithelial cells and thereby plays some important role in mammary gland.