N-acetyl-l-cysteine Ethyl Ester (NACET) Induces the Transcription Factor NRF2 and Prevents Retinal Aging and Diabetic Retinopathy

Age-related macular degeneration (AMD) and diabetic retinopathy (DR) are leading causes of visual impairment in older people, with oxidative stress playing a central role in the development of these diseases. In this study, we showed that N-acetylcysteine ethyl ester (NACET) not only increases intracellular cysteine and glutathione levels, but also strongly stimulates the expression and activity of the transcription factor NRF2, a master regulator of oxidative stress response, in RPE cells. Using RNA interference, mass spectrometry and mutagenesis of the NRF2 regulator KEAP1, we identified direct cysteinylation of the sensor residues Cys226 and Cys613 on KEAP1 as the molecular mechanism underlying NRF2 activation after NACET treatment. Furthermore, we demonstrated that oral administration of NACET induces NRF2 activity in the retina in vivo, attenuates retinal aging hallmarks, and prevents diabetes-induced retinal neurodegeneration in mouse models. These results position NACET as a promising therapeutic candidate for age- and oxidative stress-related retinal diseases such as AMD and DR.