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Sphingosine 1-phosphate stimulation of the p42/p44 mitogen-activated protein kinase pathway in airway smooth muscle. Role of endothelial differentiation gene 1, c-Src tyrosine kinase and phosphoinositide 3-kinase

Rakhit, S and Conway, A M and Tate, R and Bower, T and Pyne, N J and Pyne, S (1999) Sphingosine 1-phosphate stimulation of the p42/p44 mitogen-activated protein kinase pathway in airway smooth muscle. Role of endothelial differentiation gene 1, c-Src tyrosine kinase and phosphoinositide 3-kinase. Biochemical journal, 338 (3). pp. 643-649. ISSN 0264-6021

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Abstract

We report here that cultured airway smooth muscle cells contain transcripts of endothelial differentiation gene 1 (EDG-1), a prototypical orphan Gi-coupled receptor whose natural ligand is sphingosine 1-phosphate (S1P). This is consistent with data that showed that S1P activated both c-Src and p42/p44 mitogen-activated protein kinase (p42/p44 MAPK) in a pertussis toxin (PTX)-sensitive manner in these cells. An essential role for c-Src was confirmed by using the c-Src inhibitor, PP1, which markedly decreased p42/p44 MAPK activation. We have also shown that phosphoinositide 3-kinase (PI-3K) inhibitors (wortmannin and LY294002) decreased p42/p44 MAPK activation. An essential role for PI-3K was supported by experiments that showed that PI-3K activity was increased in Grb-2 immunoprecipitates from S1P-stimulated cells. Significantly, Grb-2 associated PI-3K activity was decreased by pretreatment of cells with PTX. Finally, we have shown that the co-stimulation of cells with platelet-derived growth factor (PDGF) and S1P (which failed to stimulate DNA synthesis) elicited a larger p42/p44 MAPK activation over a 30 min stimulation compared with each agonist alone. This was associated with a S1P-dependent increase in PDGF-stimulated DNA synthesis. These results demonstrate that S1P activates c-Src and Grb-2-PI-3K (intermediates in the p42/p44 MAPK cascade) via a PTX-sensitive mechanism. This action of S1P is consistent with the stimulation of EDG-1 receptors. S1P might also function as a co-mitogen with PDGF, producing a more robust activation of a common permissive signal transduction pathway linked to DNA synthesis.

Item type: Article
ID code: 34948
Keywords: animals, calcium-calmodulin-dependent protein kinases, cell line, enzyme activation, guinea pigs, immediate-early proteins, lysophospholipids, muscle, smooth, phosphatidylinositol 3-kinases, receptors, cell surface, receptors, G-protein-coupled, receptors, growth factor, receptors, lysophospholipid, signal transduction, sphingosine, trachea, transcriptional activation, src-family kinases, Pharmacy and materia medica, Biochemistry, Cell Biology, Molecular Biology
Subjects: Medicine > Pharmacy and materia medica
Department: Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences
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    Depositing user: Pure Administrator
    Date Deposited: 15 Nov 2011 16:11
    Last modified: 05 Sep 2014 12:36
    URI: http://strathprints.strath.ac.uk/id/eprint/34948

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