NF‐κB is a transcription factor tha

NF‐κB is a transcription factor that acts as a key regulator of stressresponse and plays a crucial role in cell injury.29 NF‐κB activation iscontrolled by the sequential phosphorylation, ubiquitination, and degradation of its inhibitory subunit IκB. The rapid degradation of IκBαenables nuclear translocation of NF‐κB, which then binds specificDNA motifs in the promoter/enhancer regions of target genes to activate transcription.30,31 In our experimental conditions, cytoplasmicIκBα was prominently accumulated time dependently in MNU‐treatedretina, indicating that increased IκBα would block NF‐κB nuclear translocation. Consistently, only low levels of p65 protein in the nuclearextracts were detected at P1, and nuclear p65 protein was notdetected at P3, P5, and P7. These data demonstrate that nuclear p65subunit of NF‐κB may be important for photoreceptor cell survival,and MNU may inhibit NF‐κB activity to promote photoreceptor celldeath.