MCB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Adomeit, A.
Right arrow Articles by Liebmann, C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Adomeit, A.
Right arrow Articles by Liebmann, C.

Molecular and Cellular Biology, August 1999, p. 5289-5297, Vol. 19, No. 8
0270-7306/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.

Bradykinin B2 Receptor-Mediated Mitogen-Activated Protein Kinase Activation in COS-7 Cells Requires Dual Signaling via Both Protein Kinase C Pathway and Epidermal Growth Factor Receptor Transactivation

Antje Adomeit,1 Angela Graness,1 Steffen Gross,2 Klaus Seedorf,3 Reinhard Wetzker,2 and Claus Liebmann1,*

Institute of Biochemistry and Biophysics, Biological and Pharmaceutical Faculty, Friedrich Schiller University, D-07743 Jena,1 and Research Group "Molecular Cell Biology," Medical Faculty, Friedrich Schiller University, D-07747 Jena,2 Germany, and Hagedorn Research Institute, Department of Molecular Signaling, 2820 Gentofte, Denmark3

Received 14 December 1998/Returned for modification 4 February 1999/Accepted 25 March 1999

The signaling routes linking G-protein-coupled receptors to mitogen-activated protein kinase (MAPK) may involve tyrosine kinases, phosphoinositide 3-kinase gamma  (PI3Kgamma ), and protein kinase C (PKC). To characterize the mitogenic pathway of bradykinin (BK), COS-7 cells were transiently cotransfected with the human bradykinin B2 receptor and hemagglutinin-tagged MAPK. We demonstrate that BK-induced activation of MAPK is mediated via the alpha  subunits of a Gq/11 protein. Both activation of Raf-1 and activation of MAPK in response to BK were blocked by inhibitors of PKC as well as of the epidermal growth factor (EGF) receptor. Furthermore, in PKC-depleted COS-7 cells, the effect of BK on MAPK was clearly reduced. Inhibition of PI3-Kgamma or Src kinase failed to diminish MAPK activation by BK. BK-induced translocation and overexpression of PKC isoforms as well as coexpression of inactive or constitutively active mutants of different PKC isozymes provided evidence for a role of the diacylglycerol-sensitive PKCs alpha  and varepsilon  in BK signaling toward MAPK. In addition to PKC activation, BK also induced tyrosine phosphorylation of EGF receptor (transactivation) in COS-7 cells. Inhibition of PKC did not alter BK-induced transactivation, and blockade of EGF receptor did not affect BK-stimulated phosphatidylinositol turnover or BK-induced PKC translocation, suggesting that PKC acts neither upstream nor downstream of the EGF receptor. Comparison of the kinetics of PKC activation and EGF receptor transactivation in response to BK also suggests simultaneous rather than consecutive signaling. We conclude that in COS-7 cells, BK activates MAPK via a permanent dual signaling pathway involving the independent activation of the PKC isoforms alpha  and varepsilon  and transactivation of the EGF receptor. The two branches of this pathway may converge at the level of the Ras-Raf complex.

* Corresponding author. Mailing address: Institute of Biochemistry and Biophysics, Friedrich Schiller University Jena, Philosophenweg 12, D-07743 Jena, Germany. Phone: 49-3641-949357. Fax: 49-3641-949352. E-mail: b9licl{at}rZ.uni-jena.de.

Molecular and Cellular Biology, August 1999, p. 5289-5297, Vol. 19, No. 8
0270-7306/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. J. Virol. Eukaryot. Cell
Microbiol. Mol. Biol. Rev. Clin. Vaccine Immunol. All ASM Journals

Copyright © 1999 by the American Society for Microbiology. All rights reserved.