LncRNA gadd7 promotes mitochondrial membrane potential decrease and apoptosis of alveolar type II epithelial cells by positively regulating MFN1 in an in vitro model of hyperoxia-induced acute lung injury

Hyperoxia-induced acute lung injury (HALI) is a complication of oxygen therapy. LncRNA gadd7 shows associations with HALI. We explored the effects of gadd7 on mitochondrial membrane potential (MMP) and apoptosis of alveolar type II epithelial cells (AEC II) in HALI. RLE-6TN cells were transfected with 50 nM silenced and overexpressed gadd7 and MFN1 plasmids (sh-gadd7, oe-gadd7 and/or oe-MFN1), respectively for 48 h, followed by hyperoxic culture for 24 h. gadd7 and MFN1 levels were assessed by RT-qPCR and Western blot. RLE-6TN cells were stained by JC-1 and MMP changes were observed using a fluorescence microscope. The average fluorescence intensity of red and green fluorescence was evaluated with the help of Image J software, and the ratio of red/green fluorescence intensity represented MMP. Cell apoptosis was assessed by flow cytometry using Annexin V-FITC/PI double staining method. The levels of apoptosis proteins [Bax, Bcl-2, Cleaved caspase-3, Cleaved poly ADP-ribose polymerase (PARP)] were measured by Western blot. LncRNA gadd7 and MFN1 were highly expressed in hyperoxia-induced AEC II. Hyperoxia induced MMP decrease and apoptosis promotion in RLE-6TN cells. LncRNA gadd7 positively regulated MFN1 expression. Knockdown of gadd7 inhibited MMP decrease and apoptosis of hyperoxia-induced RLE-6TN cells. MFN1 overexpression annulled the inhibitory effects of gadd7 silencing on MMP decrease and apoptosis in RLE-6TN cells. Briefly, lncRNA gadd7 promoted MMP decrease and apoptosis of AEC II by positively regulating the expression of MFN1 in the HALI model in vitro.