Role of LC3II in hyperoxia-induced apoptosis in alveolar typeII epithelial cells

Objective To investigate the role of microtubule-associated protein 1 light chain 3 Ⅱ (LC3 Ⅱ) in hyperoxia-induced apoptosis in alveolar typeⅡ epithelial cells. Methods A549 cells were seeded in 6-well culture plates at a density of 1×105 cells/ml (0.5 ml/well) and were divided into 3 groups (n=12 each) using a random number table method: control group (group C), 95% oxygen group (group 95% O2) and 95% oxygen plus autophagy inhibitor 3-methyladenine (3-MA) group (group 95% O2+ 3-MA). Cells in group C were cultured in incubators containing 95% air and 5% CO2 at 37 ℃.Cells were cultured in sealed chambers flushed with 95% O2 and 5% CO2 at 37 ℃ in group 95% O2 and group 95% O2+ 3-MA.The cells in each well were pretreated with 3-MA 5 mmol/L before exposure to 95% O2 in group 95% O2+ 3-MA.When the A549 cells were incubated for 24 h, 6 wells in each group were selected to detect the expression of LC3Ⅱ protein and caspase-3 using Western blot, and the left 6 wells in each group were selected to calculate the cell mortality rate by trypan blue dye. Results Compared with group C, the expression of LC3Ⅱ and caspase-3 was significantly up-regulated, and the cell mortality rate was increased in group 95% O2 and group 95% O2+ 3-MA (P<0.05). Compared with group 95% O2, the expression of LC3Ⅱ was significantly down-regulated, the expression of caspase-3 was up-regulated, and the cell mortality rate was increased in group 95% O2 and group 95% O2+ 3-MA (P<0.05). Conclusion The up-regulated expression of LC3Ⅱ can inhibit hyperoxia-induced apoptosis in alveolar typeⅡ epithelial cells. Key words: Microtubule-associated proteins; Oxygen; Pulmonary alveoli; Epithelial cells; Apoptosis