ETA receptor mediates the signaling of endothelin-1 in osteoblast-like cells.
We previously reported that endothelin-1 (ET-1) stimulates phosphatidylcholine-hydrolyzing phospholipase D independently of phosphoinositide hydrolysis in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the characteristics of the receptors mediating ET-1-induced intracellular signaling pathway in MC3T3-E1 cells. Cyclo-D-Trp-D-Asp-Pro-D-Val-Leu (BQ123), a selective ETA receptor antagonist, significantly inhibited the ET-1-induced formation of inositol phosphates in a dose-dependent manner in the range between 22 nmol/L (IC50) and 2.2 mumol/L (IC50 x 100). On the contrary, N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma MeLeu-D-Trp(COOMe)-D-Nle-ONa (BQ788), a selective ETB receptor antagonist, had no effect on the ET-1-induced formation of inositol phosphates in the range between 1.2 nmol/L (IC50) and 120 nmol/L (IC50 x 100). BQ123 significantly suppressed the ET-1-induced formation of choline dose-dependently, however, BQ788 did not affect the choline formation. BQ123 also inhibited the ET-1-induced release of arachidonic acid, but BQ788 had little effect. The results strongly suggest that ETA receptor mediates the three intracellular signaling pathways of ET-1: (1) phosphoinositide hydrolysis by phospholipase C; (2) phosphatidylcholine hydrolysis by phospholipase D; (3) arachidonic acid release in osteoblast-like cells.
Suzuki
A
A
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Shinoda
J
J
Watanabe-Tomita
Y
Y
Ozaki
N
N
Oiso
Y
Y
Kozawa
O
O
D016475:3T3 Cells; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000378:metabolism* / Q000494:pharmacology; D007295:Inositol Phosphates / Q000096:biosynthesis; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000494:pharmacology; D010713:Phosphatidylcholines / Q000378:metabolism; D010739:Phospholipase D / Q000378:metabolism; D010880:Piperidines / Q000494:pharmacology; D044022:Receptor, Endothelin A; D017466:Receptors, Endothelin / Q000187:drug effects / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism
D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D007295:Inositol Phosphates; D009842:Oligopeptides; D010456:Peptides, Cyclic; D010713:Phosphatidylcholines; D010880:Piperidines; D044022:Receptor, Endothelin A; D017466:Receptors, Endothelin; D016718:Arachidonic Acid; C086539:BQ 788; D010738:Type C Phospholipases; D010739:Phospholipase D; C072247:cyclo(Trp-Asp-Pro-Val-Leu)