PKC and MAPKs pathways mediate EGF-induced stimulation of 2-deoxyglucose uptake in mouse embryonic stem cells

It has been reported that epidermal growth factor (EGF) and EGF receptor were highly expressed in embryo, suggesting that the EGF system is related to early embryo development in an autocrine and/ or paracrine manner. Glucose becomes the preimplantation exogenous energy substrate and enters the blastocyst via glucose transporters. Thus, the effect of EGF on [H-3]-2-deoxyglucose (2-DG) uptake and its related signaling pathways were examined in mouse embryonic stem (ES) cells. EGF significantly increased 2- DG uptake in time- and concentration-dependent manner (> 12 hr, > 10 ng/ ml) and increased mRNA and protein level of glucose transporter 1 (GLUT1) compared to control, respectively. Actinomycin D and cycloheximide completely blocked the effect of EGF on 2-DG uptake. EGF-induced increase of 2-DG uptake was blocked by AG1478 (EGF receptor tyrosine kinase blocker), genistein or herbimycin (tyrosine kinase inhibitors). In addition, EGF effect was blocked by neomycin and U 73122 [phospholipase C (PLC) inhibitors] as well as staurosporine and bisindolylmaleimide I [protein kinase C (PKC) inhibitors]. EGF was also observed to increase inositol phosphates (IPs) formation and activate a PKC translocation from the cytosolic to membrane fraction, suggesting a role of PLC and PKC. SB 203580 [p38 mitogen activated protein kinase (MAPK) inhibitor] or PD 98059 (p44/42 MAPKs inhibitor) blocked EGF-induced increase of 2-DG uptake. EGF also increased phosphorylation of p38 MAPK and p44/42 MAPKs, which was blocked by genistein or bisindolylmaleimide I, respectively. In conclusion, EGF partially increased 2-DG uptake via PKC, p38 MAPK, and p44/42 MAPKs in mouse ES cells.