Mechanism of stimulation of glucose transport by H2O2: Role of phospholipase C

Exposure of Clone 9 cells, a rat liver cell line, to hydrogen peroxide (H2O 2) resulted in a striking and rapid stimulation of glucose transport (8- to 10-fold in 1 h). A comparable response was found in 3T3-L1 preadipocytes, C2C12 myoblasts, and NIH 3T3 fibroblasts, which, similar to Clone 9 cells, express only the Glut 1 glucose transporter isoform. The enhancement of glu cose transport in Clone 9 cells in response to H2O2 was significantly atten uated by genistein and the phospholipase C (PLC) inhibitor, U73122. Exposur e to H2O2 resulted in a rise in cell sn-1,2-diacylglycerol content, and the rise was significantly inhibited by U73122. Moreover, the H2O2-induced sti mulation of glucose transport was significantly blocked by thapsigargin. Ne ither staurosporine nor a 24-h preincubation in the presence of phorbol-12- myristate-13-acetate (TPA) affected the stimulatory effect of hydrogen pero xide on glucose transport. The activity of big mitogen-activated kinase (BM K1) and bf stress-activated protein kinase (SAPK), both members of mitogen- activated protein kinases, were enhanced in response to exposure to H2O2; h owever, neither protein kinase appeared to be linked to the enhancement of glucose transport by H2O2. It is concluded that the stimulation of glucose transport in response to H2O2 is independent of changes in PKC, BMK1, and S APK activity, and is mediated, at least in part, through H2O2-induced stimu lation of protein tyrosine kinase and PLC pathways. (C) 1999Academic Press.