Choline phosphate potentiates sphingosine-1-phosphate-induced Raf-1 kinase activation dependent of Ras--phosphatidylinositol-3-kinase pathway.
In NIH3T3 cells, sphingosine-1-phosphate ( S1P) caused a significant increase of Raf-1 kinase activity as early as 2 min. Interestingly, choline phosphate (ChoP) produced synergistic increase of S1P- stimulated Raf-1 kinase activation in the presence of ATP while showing additive effect in the absence of ATP. However, Raf-1 kinase activation induced by S1P decreased in the presence of ATP when applied alone. The overexpression of N-terminal fragment of Raf-1 (RfI) to inhibit Raf--Ras interaction caused the inhibition of S1P- induced Raf-1 kinase activation. Also, wortmannin, phosphatidylinositol-3-kinase ( PI3K) inhibitor, exhibited inhibitory effects on S1P- induced activation of Raf-1 kinase. In addition, we demonstrated that the chemical antioxidant, N-acetylcysteine attenuated Raf-1 activation induced by S1P, suggesting that H(2)O(2) may be required for the signalling pathway leading to Raf-1 activation. This H(2)O(2)-induced Raf-1 kinase activation was also blocked by inhibition of Ras--PI3K signalling pathway using alpha-hydroxyfarnesylphosphonic acid and wortmannin. Taken together, these results indicate that S1P- induced Raf-1 kinase activation is mediated by H(2)O(2) stimulation of Ras--PI3K pathway, and is enhanced by ChoP in the presence of ATP.[1]References
- Choline phosphate potentiates sphingosine-1-phosphate-induced Raf-1 kinase activation dependent of Ras--phosphatidylinositol-3-kinase pathway. Lee, M., Han, S.S. Cell. Signal. (2002) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
