Insulin-like Effects of Sodium Orthovanadate on Diacylglycerol-Protein Kinase C Signaling in BC3H-1 Myocytes

In this paper we examine whether sodium orthovanadate activates diacylglycerol (DAG)/protein kinase C (PKC) signaling systems that are activated by insulin in BC3H-1 myocytes. Like insulin, sodium orthovanadate provoked increases in membrane DAG, PKC enzyme activity, and immunoreactive PKC-β. Concomitantly, both PKC enzyme activity and immunoreactive PKC-β decreased in the cytosol, suggesting that sodium orthovanadate, like insulin, stimulated the translocation of PKC-β from the cytosol to the membrane fraction. Sodium orthovanadate was also found to activate phospholipid signaling pathways that were previously reported to be activated by insulin, viz., inositol-lipid synthesis/turnover; phosphatidylcholine hydrolysis; and de novo phospholipid synthesis by activation of glycerol-3-PO4 acyltransferase. Our findings suggest that vanadate mimicks insulin in the activation of specific phospholipid/DAG/PKC signaling pathways.