Expression analysis of protease-activated receptor-2 in cats

Chronic kidney disease (CKD) is a common disease in geriatric cats. Despite its high prevalence, the pathogenesis of feline CKD is poorly understood. Recently, there has been increasing evidence for the role of protease-activated receptor-2 (PAR-2) in the progression of CKD in humans and rodents. However, the role of PAR-2 in feline CKD has not been evaluated. In this study, we determined nucleotide sequence of feline PAR-2 from the kidney, evaluated PAR-2 mRNA and protein expression in normal feline tissues, and analyzed functional expression in the feline kidney epithelial cell line Crandell-Rees Feline Kidney (CRFK). The open reading frame of feline PAR-2 comprised 1,194 bp and encoded 397 amino acids, showing 90%, 90%, and 85% identities to human, dog, and mouse PAR-2, respectively. In healthy cats, expression levels of the PAR-2 mRNA and protein were relatively higher in the gastrointestinal tract and kidney, and was lowest in the heart. The feline PAR-2 protein expression was confirmed, and stimulation of trypsin and PAR-2 agonists induced a prompt increase in the intracellular calcium ion concentration in CRFK cells. The present study will provide fundamental information for investigation of the involvement of PAR-2 in the pathogenesis of CKD in cats.