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Gi-mediated activation of the p21ras-mitogen-activated protein kinase pathway by alpha 2-adrenergic receptors expressed in fibroblasts

Gi-mediated activation of the p21ras-mitogen-activated protein kinase pathway by alpha 2-adrenergic receptors expressed in fibroblasts

Authors :
Peter L. Hordijk
Wouter H. Moolenaar
Graeme Milligan
E J van Corven
Jacqueline Alblas
Other departments
Source :
Journal of biological chemistry, 268(30), 22235-22238. American Society for Biochemistry and Molecular Biology Inc.
Publication Year :
1993

Abstract

The alpha 2-adrenergic receptors are linked to inhibition of adenylylcyclase and, under certain circumstances, to stimulation of phospholipid hydrolysis via pertussis toxin-sensitive G proteins. Here we show that alpha 2-adrenergic receptors can couple to an alternative signaling pathway. When expressed in Rat-1 cells, stimulation of the alpha 2A receptor, which couples to Gi2 and Gi3, causes rapid, transient activation of the protooncogene product p21ras as measured by an increase in the amount of bound GTP. Furthermore, alpha 2A receptor stimulation causes rapid phosphorylation of the p42 mitogen-activated protein (MAP) kinase. Pertussis toxin completely inhibits both p21ras activation and MAP kinase phosphorylation, but both responses appear to be independent of adenylylcyclase inhibition or phospholipase stimulation. Thus, alpha 2-adrenergic receptors can couple to the p21ras-MAP kinase pathway via Gi, which may explain the mitogenic potential of alpha 2 agonists in certain cell types; together with previous results, these findings further suggest that activation of this pivotal signaling pathway may be a common event in the action of Gi-coupled receptors.

Details

Language :
English
ISSN :
00219258
Database :
OpenAIRE
Journal :
Journal of biological chemistry, 268(30), 22235-22238. American Society for Biochemistry and Molecular Biology Inc.
Accession number :
edsair.doi.dedup.....5e7b4f864275bcc88cd4c762326bf609