Protease-activated receptor-1 stimulates Ca(2+)-dependent Cl(-) secretion in human intestinal epithelial cells.
The thrombin receptor, protease-activated receptor-1 (PAR-1), has wide tissue distribution and is involved in many physiological functions. Because thrombin is in the intestinal lumen and mucosa during inflammation, we sought to determine PAR-1 expression and function in human intestinal epithelial cells. RT-PCR showed PAR-1 mRNA expression in SCBN cells, a nontransformed duodenal epithelial cell line. Confluent SCBN monolayers mounted in Ussing chambers responded to PAR-1 activation with a Cl(-)-dependent increase in short-circuit current. The secretory effect was blocked by BaCl2 and the Ca(2+)-ATPase inhibitor thapsigargin, but not by the L-type Ca(2+) channel blocker verapamil or DIDS, the nonselective inhibitor of Ca(2+)-dependent Cl(-) transport. Responses to thrombin and PAR-1-activating peptides exhibited auto- and crossdesensitization. Fura 2-loaded SCBN cells had increased fluorescence after PAR-1 activation, indicating increased intracellular Ca(2+). RT-PCR showed that SCBN cells expressed mRNA for the cystic fibrosis transmembrane conductance regulator (CFTR) and hypotonicity-activated Cl(-) channel-2 but not for the Ca(2+)-dependent Cl(-) channel-1. PAR-1 activation failed to increase intracellular cAMP, suggesting that the CFTR channel is not involved in the Cl(-) secretory response. Our data demonstrate that PAR-1 is expressed on human intestinal epithelial cells and regulates a novel Ca(2+)-dependent Cl(-) secretory pathway. This may be of clinical significance in inflammatory intestinal diseases with elevated thrombin levels.
Buresi
M C
MC
Mucosal Inflammation Research Group, University of Calgary, Calgary, Alberta, T2N 4N1, Canada.
Schleihauf
E
E
Vergnolle
N
N
Buret
A
A
Wallace
J L
JL
Hollenberg
M D
MD
MacNaughton
W K
WK
D002118:Calcium / Q000502:physiology*; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism*; D000242:Cyclic AMP / Q000096:biosynthesis; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000096:biosynthesis / Q000235:genetics; D004553:Electric Conductivity; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D017136:Ion Transport; D009842:Oligopeptides / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin / Q000235:genetics / Q000502:physiology*; D013917:Thrombin / Q000494:pharmacology
C505032:CFTR protein, human; D002712:Chlorides; D009842:Oligopeptides; D012333:RNA, Messenger; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin; C113426:alanyl-4-fluorophenylalanyl-arginyl-cyclohexylalanyl-citrulline-tyrosinamide; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000242:Cyclic AMP; D013917:Thrombin; D002118:Calcium