Molecular characterization of free fatty acid receptors FFAR2 and FFAR3 in the domestic cat.

G protein-coupled receptors 41 and 43 were identified and characterized as free fatty acid receptors (FFAR) 3 and 2, respectively. FFAR2 and FFAR3 mediate short-chain fatty acids (SCFAs) as signalling molecules. The present study aimed to give molecular characterization of FFAR2 and FFAR3 in the domestic cat. High homology with that in other mammals was revealed by cDNA cloning of cat FFAR2 FFAR3. We analyzed the tissue distribution of cat FFAR2 and FFAR3 mRNA using quantitative polymerase chain reaction. The inhibition of intracellular cAMP concentrations was observed in cells transfected with cat FFAR2 or FFAR3 and treated with SCFAs. The activation of nuclear factor of activated T cells-luciferase reporter was only observed in cat FFAR2 transfected cells but not in FFAR3. Split luciferase assay (NanoLuc Binary Technology; NanoBiT) for FFAR2 or FFAR3 and Arrestin-3/β-arrestin-2 revealed acetate-/propionate-induced recruitment to cat FFAR2 or FFAR3 in CHO-K1 cells. Our results indicate that FFAR2 and FFAR3 are functional receptor proteins that are expressed in cat tissues and show differential distribution patterns.