This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Leis, H. J. Articles by Windischhofer, W. Search for Related Content PubMed PubMed Citation Articles by Leis, H. J. Articles by Windischhofer, W.

Prostaglandin Endoperoxide Synthase-2 Contributes to the Endothelin/Sarafotoxin-Induced Prostaglandin E₂ Synthesis in Mouse Osteoblastic Cells (MC3T3-E1): Evidence for a Protein Tyrosine Kinase-Signaling Pathway and Involvement of Protein Kinase C¹

University Children’s Hospital, Department of Biochemical Analysis and Mass Spectrometry, University of Graz, A-8036 Graz, Austria

Address all correspondence and requests for reprints to: Dr. Hans Jörg Leis, University Children’s Hospital, Department of Biochemical Analysis and Mass Spectrometry, Auenbruggerplatz 30, A-8036 Graz, Austria. E-mail: hans.leis{at}kfunigraz.ac.at

Endothelin (ET) peptides are potent growth factors binding to G protein-coupled receptors. Sarafotoxins (S6) isolated from Atractaspis engaddensis are highly homologous to endothelins. In this study, we have investigated the effects of endothelin/sarafotoxin peptides on the prostaglandin synthesizing system in an osteoblast-like cell line, MC3T3-E1. ET-1, ET-2, ß-ET, and S6b rapidly stimulated prostaglandin E₂ production within 5 min, whereas ET-3, S6a, and S6c did not. ET-1, ET-2, ß-ET, S6b, and S6a induced prostaglandin synthesis after 3 h of incubation. Antagonizing these effects with BQ-123, PD 142893, BQ-788, and S6c suggests signaling through an ET_A receptor subtype in osteoblasts. Long-term prostaglandin synthesis was blocked by NS-398, and reduced to short-term levels by cycloheximide and actinomycin D, indicating induction of PGHS-2. There was only minor enhancement of cAMP accumulation by the agonists, which had no effect on prostaglandin synthesis. Induction of PGHS-2 was furthermore demonstrated by Northern blot analysis of PGHS-2 messenger RNA. Depletion of protein kinase C with TPA largely blunted the response. Genistein, an inhibitor of protein tyrosine kinases, also blocked long-term prostaglandin E₂ formation. We conclude that in osteoblast-like MC3T3-E1 cells, ET-1, ET-2, ß-ET, S6b, and S6a peptides induce PGHS-2 through a protein tyrosine kinase-dependent and protein kinase C-dependent pathway, signaling through ET_A receptor occupancy.