Sphingosine-1-phosphate enhances IL-1{beta}-induced COX-2 expression in mouse intestinal subepithelial myofibroblasts.
Intestinal subepithelial myofibroblasts (SEMFs) is a specific population of cells involved in intestinal inflammation and carcinogenesis via an elaborate network of cytokines, chemokines and other inflammatory factors, including PGE(2). Sphingosine-1-phosphate (S1P) has been implicated as an important mediator of inflammation and cancer and in certain cell types increases cyclooxygenase-2 (COX-2) expression. In the present study, we aimed to assess involvement of S1P in COX-2 expression by SEMFs. Primary SEMFs were obtained from C57BL/6J mouse and their identity was verified by fluorescent staining of specific marker proteins. Expression of S1P receptors 1, 2, 3 and sphingosine kinases 1 and 2 in SEMFs were determined by RT-PCR analysis. COX-2 expression and PGE(2) production were assayed by Western blotting and ELISA, respectively. COX-2 mRNA stability was assayed by Northern blotting. S1P produced dose-dependent increase in COX-2 expression, resulting in increased PGE(2) release from SEMFs. Using specific inhibitors, we show that actions of p38, ERK, IKK, and PKC were involved in S1P-induced COX-2 expression. On the other hand, p38 and PKC had lesser roles in IL-1beta-induced COX-2 expression. Inhibition of sphingosine kinase to block S1P production did not affect IL-1beta-induced COX-2 expression, but S1P amplified IL-1beta-induced p38 activation and COX-2 expression. PKC inhibition blocked S1P amplified COX-2 expression. S1P addition increased COX-2 mRNA stability. In SEMFs, S1P amplifies IL-1beta-induced COX-2 expression through increased mRNA stability. These observations point to involvement of S1P in activation of SEMFs that may contribute to intestinal inflammation and carcinogenesis.
Ohama
Takashi
T
Dept. of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The Univ. of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
Okada
Muneyoshi
M
Murata
Takahisa
T
Brautigan
David L
DL
Hori
Masatoshi
M
Ozaki
Hiroshi
H
D000818:Animals; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D015232:Dinoprostone / Q000096:biosynthesis; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D051550:I-kappa B Kinase / Q000502:physiology; D053583:Interleukin-1beta / Q000502:physiology*; D007413:Intestinal Mucosa / Q000166:cytology; D008246:Lysophospholipids / Q000494:pharmacology*; D051379:Mice; D008954:Models, Biological; D011493:Protein Kinase C / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
D053583:Interleukin-1beta; D008246:Lysophospholipids; D012333:RNA, Messenger; C060506:sphingosine 1-phosphate; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D051550:I-kappa B Kinase; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D015232:Dinoprostone; D013110:Sphingosine