Activation of Protease-Activated Receptor-2 (PAR-2) Triggers Mucin Secretion in the Rat Sublingual Gland

• Published in: Biochemical and biophysical research communications Vol. 270; no. 1; pp. 298 - 302
• Main Authors: Kawabata, Atsufumi, Morimoto, Nao, Nishikawa, Hiroyuki, Kuroda, Ryotaro, Oda, Yasuo, Kakehi, Kazuaki
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 02.04.2000
• Subjects: Animals; Genistein - pharmacology; In Vitro Techniques; Male; mucin; Mucins - secretion; Oligopeptides - pharmacology; Phosphatidylinositol 3-Kinases - antagonists & inhibitors; protease (proteinase)-activated receptor; Protein Kinase C - antagonists & inhibitors; Protein-Tyrosine Kinases - antagonists & inhibitors; Rats; Rats, Wistar; Receptor, PAR-2; Receptors, Thrombin - agonists; Receptors, Thrombin - metabolism; Sialic Acids - secretion; sublingual gland; Sublingual Gland - metabolism; trypsin; sublingual gland; trypsin; protease (proteinase)-activated receptor; mucin
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.2000.2404

Protease-activated receptor-2 (PAR-2) is distributed throughout the gastrointestinal systems. The present study investigated the role for PAR-2 in the rat salivary glands. PAR-2 mRNA was detected in the sublingual, submaxillary, and parotid glands by a reverse-transcriptase polymerase chain reaction. In the isolated sublingual gland that exhibited the strongest signal for PAR-2, Ser-Leu-Ile-Gly-Arg-Leu-NH2, a PAR-2-activating peptide, and trypsin, a PAR-2-activating enzyme, but not thrombin that can activate PARs 1, 3, and 4, triggered secretion of N-acetylneuraminic acid, an indicator of mucin, that was a unique major sialic acid detectable after hydrolysis of the sublingual mucin with 0.1 N HCl. The PAR-2-mediated secretion of mucin was attenuated by genistein, a tyrosine kinase inhibitor, but not by inhibitors of protein kinase C and phosphatidyl inositol 3′-kinase. Thus, PAR-2 is expressed by the three distinct salivary glands in the rat, and sublingual PAR-2 appears to play a role in triggering mucin secretion, at least in part, via activation of tyrosine kinase.