[Down-regulation of SIRT1 and PGC-1α expression caused by hyperoxia induces mitochondrial dysfunction in human...

Objective To investigate SIRT1-PGC-1α signaling pathway-mediated effect of hyperoxia on mitochondrial function in A549 human alveolar epithelial cells and its possible mechanism. Methods Human alveolar epithelial cells in logarithmic growth phase were randomly divided into control group and hyperoxia group. The control group was cultured in a 37DegreesCelsius, 50 mL/L CO₂ saturated humidity incubator, and the hyperoxia group was treated with 950 mL/L O₂. Following 24-hour culture, Mito SOX^TM staining was used to detect the level of mitochondrial reactive oxygen species (Mito-ROS) and JC-1 staining to detect the mitochondrial membrane potential. Real-time quantitative PCR was performed to detect the mitochondrial DNA content and the mRNA levels of SIRT1, PGC-1α, nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM), and Western blotting to detect the protein levels of SIRT1, PGC-1α, NRF1 and TFAM. Results Compared with the control group, the Mito-ROS of the hyperoxia group increased significantly, while the membrane potential decreased obviously; the mitochondrial DNA content of the hyperoxia group went down, and the mRNA and protein expression of SIRT1, PGC-1α, NRF1 and TFAM dropped. Conclusion Hyperoxia induces mitochondrial dysfunction in human alveolar epithelial cells by inhibiting the expression of SIRT1 and PGC-1α.