Protein nitration promotes inducible nitric oxide synthase transcription mediated by NF-κB in high glucose-stimulated human lens epithelial cells.

Although an important event in hyperglycaemia-induced oxidative stress is the nuclear factor-kappa b (NF-κB)-activated inducible nitric oxide synthase (iNOS) expression, the underlying mechanism is not fully characterized. Peroxynitrite, formed from NO and superoxide, can induce multiple proteins nitration, even including NF-κB and iNOS, to alter their functions. In this study, we found high glucose caused conspicuous nitration of nuclear NF-κB p65 and its co-activator p300 in human lens epithelial cells. The nitration of NF-κB and p300 promoted their co-localization and binding to ensure the activation of the iNOS gene transcription. Moreover, nearly all predicted NF-κB binding sites in the human iNOS gene promoter were responsive to high glucose stimulation, might for a synergistic role. While, only the NF-κB binding site -5212 showed significant alterations by high glucose and peroxynitrite stimulations, indicating it a more important role in the protein nitration promoted iNOS gene transcription. Our results demonstrated that protein nitration can promote the NF-κB-activated iNOS gene transcription in human lens epithelial cells by high glucose stimulation.