Involvement of SAPK/JNK in prostaglandin E(1)-induced VEGF synthesis in osteoblast-like cells.
We previously reported that prostaglandin E(1) (PGE(1)) activates both p44/p42 mitogen-activated protein (MAP) kinase and p38 MAP kinase via cAMP-dependent protein kinase in osteoblast-like MC3T3-E1 cells, and that p38 MAP kinase but not p42/p44 MAP kinase is involved in PGE(1)-induced synthesis of vascular endothelial growth factor (VEGF). In the present study, we investigated the involvement of stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) in the PGE(1)-induced VEGF synthesis in MC3T3-E1 cells. PGE(1) induced the phosphorylation of SAPK/JNK. SP600125, a specific inhibitor of SAPK/JNK, markedly reduced the PGE(1)-induced VEGF synthesis. Forskolin, a direct activator of adenylyl cyclase, elicited the phosphorylation of SAPK/JNK, and 8bromo-cAMP, a plasma membrane-permeable cAMP analogue-stimulated VEGF synthesis was significantly reduced by SP600125. SP600125 suppressed the PGE(1)-induced phosphorylation of SAPK/JNK without affecting the phosphorylation of p38 MAP kinase induced by PGE(1). The phosphorylation of c-Jun induced by PGE(1) was also inhibited by SP600125. SB203580, a p38 MAP kinase inhibitor, failed to reduce the PGE(1) induced phosphorylation of SAPK/JNK. A combination of SP600125 and SB203580 suppressed the PGE(1)-stimulated VEGF synthesis in an additive manner. These results strongly suggest that PGE(1) activates SAPK/JNK in osteoblasts, and that SAPK/JNK plays a part in PGE(1)-induced VEGF synthesis.
Kanno
Y
Y
Department of Pharmacology, Gifu University School of Medicine, Gifu 500-8705, Japan.
Tokuda
H
H
Nakajima
K
K
Ishisaki
A
A
Shibata
T
T
Numata
O
O
Kozawa
O
O
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000527:Alprostadil / Q000494:pharmacology*; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D000873:Anthracenes; D007093:Imidazoles; D016755:Proto-Oncogene Proteins c-jun; D011725:Pyridines; D042461:Vascular Endothelial Growth Factor A; D005576:Colforsin; C432165:pyrazolanthrone; D015124:8-Bromo Cyclic Adenosine Monophosphate; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D000527:Alprostadil; C093642:SB 203580