PAR-2 modulates pepsinogen secretion from gastric-isolated chief cells.
In the present study, we investigated whether activation of protease-activated receptor type 2 (PAR-2) with SLIGRL (SL)NH2, a short mimetic agonistic peptide, directly stimulates pepsinogen secretion from gastric-isolated, pepsinogen-secreting (chief) cells. Immunostaining of gastric-dispersed chief cells with a specific anti-PAR-2 antibody demonstrated expression of PAR-2 receptors on membrane and cytoplasm. SL-NH2 and trypsin potently stimulated pepsinogen secretion (EC50 = 0.3 nM) and caused Ca2+ mobilization (EC50 = 0.6 nM). In contrast to SL-NH2, the scramble peptide LSIGRL-NH2 failed to stimulate pepsinogen release. Exposure to SL-NH2 also resulted in ERK1/2 phosphorylation and activation. Exposure of chief cells to phosphotyrosine kinase inhibitors and 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one, a selective MEK inhibitor, significantly reduced secretion induced by SL-NH2. Pepsinogen secretion induced by SL-NH2 was desensitized by pretreating the cells with the mimetic peptide and trypsin, and exposure to SL-NH2 abrogates pepsinogen secretion induced by carbachol and CCK-8, but not secretion induced by secretin and vasointestinal peptide. Exposure to Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2 (substance P) but not to calcitonin gene-related peptide increased pepsinogen release. The neurokinin-1 receptor antagonist, N-acetyl-l-tryptophan 3,5-bis(trifluoromethyl)benzyl ester, inhibited substance P-stimulated pepsinogen secretion, whereas it did not affect secretion induced by SL-NH2. Collectively, these data indicate that PAR-2 is expressed on gastric chief cells and that its activation causes a Ca2+-ERK-dependent stimulation of pepsinogen secretion.
Dipartimento di Medicina Clinica, Universitá di Perugia, 06122 Perugia, Italy. fiorucci@unipg.it
Stefano
S
Fiorucci
Eleonora
E
Distrutti
Barbara
B
Federici
Barbara
B
Palazzetti
Monia
M
Baldoni
Antonio
A
Morelli
Giuseppe
G
Cirino
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D019872:Chief Cells, Gastric / Q000187:drug effects / Q000378:metabolism*; D006168:Guinea Pigs; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D020116:Pepsinogen A / Q000378:metabolism*; D010766:Phosphorylation; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin / Q000502:physiology*; D013373:Substance P / Q000494:pharmacology
D009842:Oligopeptides; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin; C099570:seryl-leucyl-isoleucyl-glycyl-arginyl-leucine; D013373:Substance P; D020116:Pepsinogen A; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium