Anisomycin induces COX-2 mRNA expression through p38(MAPK) and CREB independent of small GTPases in intestinal epithelial cells.
Cyclooxygenase (COX)-2 expression in intestinal epithelial cells is associated with colorectal carcinogenesis. COX-2 expression is induced by numerous growth factors and gastrointestinal hormones through multiple protein kinase cascades. Here, the role of mitogen activated protein kinases (MAPKs) and small GTPases in COX-2 expression was investigated. Anisomycin and sorbitol induced COX-2 expression in non-transformed, intestinal epithelial IEC-18 cells. Both anisomycin and sorbitol activated p38(MAPK) followed by phosphorylation of CREB. SB202190 and PD169316 but neither PD98059 nor U0126 blocked COX-2 expression and CREB phosphorylation by anisomycin or sorbitol. Clostridium difficile toxin B inhibition of small GTPases did not affect anisomycin-induced COX-2 mRNA expression or phosphorylation of p38MAPK and CREB but did inhibit sorbitol-dependent COX-2 expression and phosphorylation of p38MAPK and CREB. Angiotensin (Ang) II-dependent induction of COX-2 mRNA and induced phosphorylation of p38MAPK and CREB were inhibited by toxin B. Reduction of CREB protein in cells transfected with CREB siRNAs inhibited anisomycin-induced COX-2 expression. These results indicate that activation of p38MAPK signaling is sufficient for COX-2 expression in IEC-18 cells. Ang II and sorbitol require small GTPase activity for COX-2 expression via p38MAPK while anisomycin-induced COX-2 expression by p38MAPK does not require small GTPases. This places small GTPase activity down-stream of the AT1 receptor and hyperosmotic stress and up-stream of p38MAPK and CREB.
Shafer
Lindsay M
LM
Department of Medicine, David Geffen School of Medicine, CURE: Digestive Diseases Research Center, Jonnson Comprehensive Cancer Center and the Molecular Biology Institute, University of California, Los Angeles, CA 90095-1786, USA.
Slice
Lee W
LW
D000818:Animals; D000841:Anisomycin / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000633:toxicity; D001427:Bacterial Toxins / Q000633:toxicity; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D017931:DNA Primers; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000378:metabolism*; D020559:Monomeric GTP-Binding Proteins / Q000037:antagonists & inhibitors; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D013012:Sorbitol / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D002070:Butadienes; D017362:Cyclic AMP Response Element-Binding Protein; D017931:DNA Primers; D005419:Flavonoids; D007093:Imidazoles; D009570:Nitriles; D011725:Pyridines; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C113580:U 0126; C031815:toxB protein, Clostridium difficile; D013012:Sorbitol; D000841:Anisomycin; D051546:Cyclooxygenase 2; C489691:Ptgs2 protein, rat; D048051:p38 Mitogen-Activated Protein Kinases; D020559:Monomeric GTP-Binding Proteins; C408604:2-(4-nitrophenyl)-4-(4-fluorophenyl)-5-(4-pyridinyl)-1H-imidazole; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one