MAFF Expression Reshapes Key Stress-Response Proteins During Light-Induced Injury

MAFF is a small MAF family transcription factor involved in antioxidant signaling and cytoprotective gene regulation. MAFF is differentially expressed across retinal regions, with particularly low expression in macular Müller cells, which play a central role in retinal redox balance. Reduced MAFF expression may weaken macular resilience to oxidative stress (OS), increasing susceptibility to age-related macular degeneration (AMD) and macular telangiectasia type 2. However, the function of MAFF in Müller cells remains unclear. Human primary Müller cells (huPMCs) from non-diseased human donor eyes were used to investigate MAFF modulation under stress. Cells were transfected with MAFF plasmid DNA to evaluate intracellular reactive oxygen species (ROS) following H₂O₂-induced stress. For functional and proteomic analyses, MAFF was overexpressed using mRNA or knocked down using siRNA and validated by Western blot. huPMCs were exposed to light stress and cell viability was assessed using the AlamarBlue assay. Molecular changes were characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based quantitative proteomics. MAFF upregulation significantly reduced intracellular ROS following H₂O₂-induced stress. MAFF protein expression decreased following siRNA-mediated knockdown (KD) and increased following mRNA-mediated overexpression (OE). MAFF OE improved Müller cell viability under light stress, whereas MAFF KD reduced viability. Exploratory proteomic profiling quantified 5907 proteins and identified candidate molecular changes associated with MAFF expression. Pathway analyses suggested that reduced MAFF expression was associated with oxidative-stress response signatures, whereas elevated MAFF expression was associated with changes in mitochondrial and immune/inflammatory pathways. KEAP1, BMP2K, VPS28, and PDCD4 were negatively associated with MAFF expression, suggesting potential regulation of antioxidant defense, vesicle trafficking, and apoptosis-related processes. Elevated MAFF expression was associated with reduced ROS accumulation and improved cell viability, while exploratory proteomic analysis identified changes in mitochondrial, oxidative-stress, and immune/inflammatory pathways. These findings support further investigation of MAFF as a contributor to macular stress susceptibility and as a candidate for future therapeutic studies.