Mechanisms for prostaglandin E2 formation caused by proteinase-activated receptor-1 activation in rat gastric mucosal epithelial cells.
Proteinase-activated receptor-1 (PAR1), a thrombin receptor, plays a protective role in gastric mucosa via prostanoid formation. Thus, we studied effects of PAR1 stimulation on prostaglandin E(2) (PGE(2)) formation in rat normal gastric mucosal epithelial RGM1 cells and analyzed the underlying signal transduction mechanisms. The PAR1-activating peptide (PAR1-AP) and thrombin increased PGE(2) release from RGM1 cells for 18h, an effect being suppressed by inhibitors of COX-1, COX-2, MEK, p38 MAP kinase (p38 MAPK), protein kinase C (PKC), Src and EGF receptor-tyrosine kinase (EGFR-TK), but not JNK and matrix metalloproteinase (MMP)/a disintegrin and metalloproteinases (ADAMs). PAR1-AP caused persistent (6h or more) and transient (5min) phosphorylation of ERK and p38 MAPK, respectively, followed by delayed reinforcement at 18h. PAR1-AP up-regulated COX-2 in a manner dependent on MEK and EGFR-TK, but not p38 MAPK. The PAR1-mediated persistent ERK phosphorylation was reduced by inhibitors of Src and EGFR-TK. PAR1-AP actually phosphorylated EGF receptors and up-regulated mRNA for heparin-binding-EGF (HB-EGF), the latter effect being blocked by inhibitors of Src, EGFR-TK and MEK. Heparin, an inhibitor for HB-EGF, suppressed PAR1-mediated PGE(2) formation and persistent ERK phosphorylation. These results suggest that PAR1 up-regulates COX-2 via persistent activation of MEK/ERK that is dependent on EGFR-TK activation following induction of HB-EGF, leading to PGE(2) formation. In addition, our data also indicate involvement of COX-1, PKC and p38 MAPK in PAR1-triggered PGE(2) formation. PAR1, thus stimulates complex multiple signaling pathways responsible for PGE(2) formation in RGM1 cells.
Sekiguchi
Fumiko
F
Division of Physiology and Pathophysiology, School of Pharmacy, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502, Japan.
Saito
Shino
S
Takaoka
Kaori
K
Hayashi
Hitomi
H
Nagataki
Mami
M
Nagasawa
Keita
K
Nishikawa
Hiroyuki
H
Matsui
Hirofumi
H
Kawabata
Atsufumi
A
D000818:Animals; D001483:Base Sequence; D051546:Cyclooxygenase 2 / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D017931:DNA Primers; D015232:Dinoprostone / Q000096:biosynthesis*; D004815:Epidermal Growth Factor / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism; D005753:Gastric Mucosa / Q000166:cytology / Q000378:metabolism*; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D044463:Receptor, PAR-1 / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D016861:Cyclooxygenase Inhibitors; D017931:DNA Primers; C587885:Hbegf protein, rat; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D044463:Receptor, PAR-1; D004815:Epidermal Growth Factor; D051546:Cyclooxygenase 2; D066246:ErbB Receptors; D020928:Mitogen-Activated Protein Kinases; D015232:Dinoprostone