SOD1 Overexpression Alleviates H₂O₂-Induced Oxidative Stress and Reshapes Transcriptomic Responses in Chicken DF-1 Cells

Oxidative stress is a major consequence of environmental, metabolic, and disease-related challenges in poultry and can compromise cellular integrity and function. Although antioxidant defense mechanisms are broadly conserved across vertebrates, oxidative-stress responses in avian cells remain less well characterized than those in mammalian systems. Superoxide dismutase 1 (SOD1) is a key antioxidant enzyme, but how elevated SOD1 expression influences both oxidative injury and stress-responsive transcription in chicken cells remains incompletely understood. In this study, we established a stable SOD1-overexpressing chicken DF-1 fibroblast cell line and induced acute oxidative stress using hydrogen peroxide (H₂O₂). Cellular responses were evaluated using CCK-8 viability assays and Hoechst 33342/propidium iodide staining, followed by RNA sequencing and transcriptomic analyses. SOD1 overexpression markedly improved cell viability under H₂O₂ challenge and substantially reduced necrotic cell death, whereas its effect on apoptosis-associated changes was comparatively limited. Transcriptomic profiling showed that H₂O₂ induced extensive transcriptional reprogramming, while SOD1 overexpression reshaped this response by attenuating a subset of stress-inducible gene programs. Trend clustering further identified an H₂O₂-responsive module associated mainly with basic amino acid transport and stress-related regulatory processes that was less strongly induced in SOD1-overexpressing cells. Collectively, these findings demonstrate that elevated SOD1 expression enhances resistance to acute oxidative injury and modifies stress-responsive transcription in chicken fibroblasts. This study extends our current understanding of SOD1-mediated antioxidant cytoprotection in an avian cellular model and provides a molecular basis for further investigation of oxidative-stress regulation in poultry.