Molecular cloning of canine protease-activated receptor-2 and its expression in normal dog tissues and atopic skin lesions.

Protease-activated receptor-2 (PAR-2) belongs to a new G protein-coupled receptor subfamily and is activated by serine proteases. PAR-2 has been demonstrated to play an important role in inflammation and immune response in allergic diseases. In this study, we cloned canine PAR-2 cDNA from the canine kidney by RT-PCR. The canine PAR-2 clone contained a full-length open reading frame encoding 397 amino acids that had 84% and 80% homology with human and mouse homologues, respectively. Canine PAR-2 mRNA was detected in the heart, lung, liver, pancreas, stomach, small intestine, colon, kidney, adrenal gland, spleen, thyroid gland, thymus, skeletal muscle, lymph node, fat and skin of three healthy dogs. The expression pattern of PAR-2 mRNA in canine tissues was similar to that in humans. The expression level of PAR-2 mRNA in skin was not different between the atopic dermatitis (AD) and healthy dogs, suggesting that the level of PAR-2 mRNA transcription may not be associated with development of canine AD. The canine PAR-2 cDNA clone obtained in this study will be useful for further investigation of the immunopathogenesis of canine allergic diseases.