Activation of members of the mitogen-activated protein kinase family by glucose in endothelial cells.

To better understand the molecular mechanisms for hyperglycemia-induced proatherogenic changes in endothelial cells, the effect of high glucose on activation of members of the mitogen-activated protein kinase (MAPK) family, including c-Jun NH(2)-terminal kinase (JNK), extracellular signal-regulated kinase (ERK)-1, -2, and -5, and p38 kinase, was examined in bovine pulmonary artery endothelial cells (PAEC). Glucose, fructose, and raffinose induced a concentration-dependent decrease in PAEC growth. Addition of 25 mM glucose, fructose, or raffinose to normal growth medium stimulated an approximately twofold increase in JNK1 activity that was maximal after 24 h, whereas only glucose markedly increased ERK5 activity. Neither ERK1/2 nor p38 kinase activity was increased by glucose, fructose, or raffinose. The antioxidant N-acetylcysteine partially abrogated the glucose-induced increase in ERK5 activity but had no effect on the increase in JNK1 activity. In contrast, azaserine, which prevents increased flux through the hexosamine pathway, decreased glucose-induced JNK1 activity but had no effect on fructose- or raffinose-induced JNK1 activity. Consistent with this finding, glucosamine stimulated a 2.4-fold increase in JNK1 activity and reproduced the inhibitory effect of glucose on PAEC growth. In summary, glucose activates different members of the MAPK family in PAEC via distinct mechanisms. Moreover, the correlation between the ability of different sugars to activate JNK1 and inhibit cell growth suggests that activation of this signaling pathway may contribute to the growth inhibitory effect of glucose in endothelial cells.