Study of mitochondrial energy metabolism in D-galactose-induced cell ageing model

Objective To investigate the mitochondrial energy metabolism in D-galactose-induced cell ageing model. Methods MRC-5 cells were cultivated for 72 hours in a medium containing 55 mmol/L D-galactose.The analysis of cell proliferation capacity by CCK8 method, β-galactosidase staining and detection of p21 protein expression level were performed for identifying cell senescence.The cell oxidation-reduction state was evaluated by an analysis of cellular ROS levels, SOD activity, MDA content and oxidative damage level of mitochondrial DNA(mtDNA). For purpose of detecting mitochondrial function and its impairment, mitochondrial morphology was observed by electron microscope, mitochondrial quantity was analyzed by flow cytometry, mitochondrial membrane potential(ΔΨm)was measured by JC-1 staining, and ATP content was analyzed by HPLC, and mitochondrial oxygen consumption rate was detected by Seahorse cell energy metabolism detection system. Results The decreased MRC-5 cell proliferation, up-expression of p21 protein, increased β-galactosidase activity were observed in D-Gal-treated cells, which indicated the cell premature senescence.When treated with D-Gal, the significantly increased ROS and MDA level, decreased SOD activity and increased oxidized mtDNA proved that the cells kept higher oxidative stress.D-Gal induced-mitochondrial impairment was evidenced by the dimming of mitochondrial cristae and double membrane structure, decrease of transmembrane potential and ATP synthesis, and decrease of its oxygen consumption rate(OCR). Conclusions The 55 mmol/L D-Gal causes an impairment of mitochondrial structure and a decrease of function of energy metabolism, which is associated with cellular senescence induced by D-Gal. Key words: Galactose; Cell aging; Mitochondria; Energy metabolism