Fig. 4

Melatonin regulated mitophagy to enhance cellular apoptosis in response to TNF-α treatment. a The overlap of mitochondria and lysosome in the HeLa cells under TNF-α treatment in the presence of melatonin or not. Mitophagy was activated by TNF-α treatment and was suppressed by melatonin supplementation. b The number of mitophagy in each cell was recorded. c–f Western blotting was used to analyzd the expression of mitophagy-related parameters. g, h ELISA assay was used to observe the activity of caspase-3 and caspase-9 activity. FCCP (5 μM) was used to activate the mitophagy 2 h before the melatonin and TNF-α treatment. *P < 0.05 vs. ctrl group, ^#P < 0.05 vs. TNF-α group, ^@P < 0.05 vs. TNF-α + melatonin group