Aim: 

Diabetes is associated with an increased formation of advanced glycation end-products (AGE) and oxidative stress, leading to endothelial dysfunction. Activation of the redox sensitive transcription factor Nrf2 mediates the induction of phase II and antioxidant defence genes such as NAD(P)H:quinone oxidoreductase-1 (NQO1) and heme oxygenase-1 (HO-1) (Mann et al., 2007). The present study investigates the molecular mechanisms underlying AGE-induced superoxide (O₂^-•) generation and Nrf2 mediated induction of HO-1 and NQO1 in bovine aortic (BAEC) and human umbilical vein (HUVEC) endothelial cells.

Methods: 

Confluent cell monolayers were serum-deprived (1% FCS) and then treated for 0-24 h with vehicle (BSA, 100 mg ml^-1) or AGE-BSA (100 mg ml^-1). Cell lysates were analyzed for changes in mRNA or protein expression of HO-1, NQO1 and/or GPx-1. O₂^-• production was assayed by lucigenin chemiluminescence.

Results: 

Treatment with AGE-BSA or AGE-HSA (100 mg ml^-1), but not native BSA/HSA, elicited a significant increase in O₂^-• generation, nuclear translocation of Nrf2 and increases in HO-1 mRNA (4-12 h) and protein (8-24 h) expression. Increased HO-1 protein expression induced by AGE-BSA was attenuated by inhibitors of NADPH oxidase and the JNK signaling pathway, indicating that NADPH oxidase-derived O₂^-• and the JNK signaling pathway may underlie AGE-induced gene expression.

Conclusions: 

Our findings establish that increased AGE in diabetes upregulate adaptive antioxidant gene expression in endothelial cells via the Nrf2/ARE pathway.

Mann GE et al. (2007). Cardiovasc. Res. 75: 261-274.

Supported by Heart Research UK, COST ACTION B35, K.C. Wong