Growth factor-stimulated protein synthesis is inhibited by sodium orthovanadate.
The study of intracellular signaling pathways has been aided by the use of sodium orthovanadate, a cell-permeable inhibitor of tyrosine phosphatases. However, long-term addition of sodium orthovanadate is often cytotoxic. In this study we demonstrate that the growth factor-mediated increase in the rate of protein synthesis was inhibited by sodium orthovanadate. This effect of sodium orthovanadate was dose-dependent, with an IC50 of 40 microM and maximal inhibition obtained at 100 microM. As a consequence, the fetal bovine serum-mediated induction of the immediate-early genes, c-Fos and MKP-1, at the protein level was inhibited by orthovanadate. Orthovanadate's ability to attenuate protein synthesis was partially reversible, and was no longer evident when the agent was added 6 h after addition of growth factor to cells. Analysis of several elements of signaling pathways which are known to regulate protein synthesis in a positive manner (p42/p44 MAPK, AKT and p70 S6K stimulation, and hyperphosphorylation of PHAS-I) were not inhibited but rather were stimulated by orthovanadate. Thus, sodium orthovanadate is a potent inhibitor of growth factor-stimulated protein synthesis independent of p42/p44 MAPK or PI3K-p70 S6K activation.
Viñals
F
F
Institute of Signaling, Developmental Biology and Cancer Research, Nice, France. fvinals@bell.ub.es
McKenzie
F R
FR
Pouysségur
J
J
D000818:Animals; D015153:Blotting, Western; D018797:Cell Cycle Proteins; D002460:Cell Line; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D054638:Dual Specificity Phosphatase 1; D004791:Enzyme Inhibitors / Q000494:pharmacology; D039561:Eukaryotic Initiation Factor-4E; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D006133:Growth Substances / Q000378:metabolism*; D017874:Immediate-Early Proteins / Q000378:metabolism; D020128:Inhibitory Concentration 50; D010448:Peptide Initiation Factors / Q000378:metabolism; D010749:Phosphoprotein Phosphatases; D010766:Phosphorylation; D011485:Protein Binding; D054645:Protein Phosphatase 1; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D012685:Sepharose / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013917:Thrombin / Q000378:metabolism; D013997:Time Factors; D014638:Vanadates / Q000494:pharmacology*
D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D039561:Eukaryotic Initiation Factor-4E; D006133:Growth Substances; D017874:Immediate-Early Proteins; D010448:Peptide Initiation Factors; D011500:Protein Synthesis Inhibitors; D016760:Proto-Oncogene Proteins c-fos; D016222:Fibroblast Growth Factor 2; D014638:Vanadates; D012685:Sepharose; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054638:Dual Specificity Phosphatase 1; D017027:Protein Tyrosine Phosphatases; D013917:Thrombin