Trypsin activates pancreatic duct epithelial cell ion channels through proteinase-activated receptor-2.

Abstract

Proteinase-activated receptor-2 (PAR-2) is a G protein-coupled receptor that is cleaved by trypsin within the NH2-terminus, exposing a tethered ligand that binds and activates the receptor. We examined the secretory effects of trypsin, mediated through PAR-2, on well-differentiated nontransformed dog pancreatic duct epithelial cells (PDEC). Trypsin and activating peptide (AP or SLIGRL-NH2, corresponding to the PAR-2 tethered ligand) stimulated both an 125I- efflux inhibited by Ca2+-activated Cl- channel inhibitors and a 86Rb+ efflux inhibited by a Ca2+-activated K+ channel inhibitor. The reverse peptide (LRGILS-NH2) and inhibited trypsin were inactive. Thrombin had no effect, suggesting absence of PAR-1, PAR-3, or PAR-4. In Ussing chambers, trypsin and AP stimulated a short-circuit current from the basolateral, but not apical, surface of PDEC monolayers. In monolayers permeabilized basolaterally or apically with nystatin, AP activated apical Cl- and basolateral K+ conductances. PAR-2 agonists increased [Ca2+]i in PDEC, and the calcium chelator BAPTA inhibited the secretory effects of AP. PAR-2 expression on dog pancreatic ducts and PDEC was verified by immunofluorescence. Thus, trypsin interacts with basolateral PAR-2 to increase [Ca2+]i and activate ion channels in PDEC. In pancreatitis, when trypsinogen is prematurely activated, PAR-2-mediated ductal secretion may promote clearance of toxins and debris.

• Authors: T D Nguyen, M W Moody, M Steinhoff, C Okolo, D S Koh, N W Bunnett
• Journal: The Journal of clinical investigation (J Clin Invest) Vol. 103 Issue 2 Pg. 261-9 (Jan 1999) ISSN: 0021-9738 [Print] United States
• PMID: 9916138 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Iodine Radioisotopes
• Ion Channels
• Oligopeptides
• Peptides
• Receptor, PAR-2
• Receptors, Thrombin
• Rubidium Radioisotopes
• seryl-leucyl-isoleucyl-glycyl--arginyl-leucinamide
• Trypsin
• Thrombin
• Calcium

Topics

• Animals
• Calcium (metabolism)
• Cells, Cultured
• Dogs
• Fluorescent Antibody Technique
• Iodine Radioisotopes (metabolism)
• Ion Channels (metabolism)
• Ion Transport (drug effects)
• Oligopeptides (pharmacology)
• Pancreatic Ducts (cytology, metabolism)
• Peptides (pharmacology)
• Receptor, PAR-2
• Receptors, Thrombin (agonists, metabolism)
• Rubidium Radioisotopes (metabolism)
• Signal Transduction (physiology)
• Thrombin (pharmacology)
• Trypsin (pharmacology)