AMPK activation promotes mitochondrial quality control under nutrient starvation. ARPE-19 cells were starved with HBSS medium in the presence or absence of Met (1 mM; pre-treated for 2 h) for 36 h. (A) Fluorescence microscopy images of DCF-DA-stained ARPE-19 cells. Scale bar: 275 μm. Bar graph indicates the fluorescence intensity of DCF, which was normalized to starvation 0 h in the presence or absence of Met. Data are presented as the mean ± SEM, n = 3. **P < 0.01. (B) Images of PGC1-α-immunostained (green) ARPE-19 cells under nutrient starvation for 36 h in the presence or absence of Met. Nuclei were stained with DAPI (blue). Scale bar: 10 μm. (C) MitoTracker Red-stained cells under nutrient starvation for 36 h in the presence or absence of Met. Nuclei were stained with DAPI (blue). Scale bar: 10 μm. (D) TEM images showing mitochondrial internal structures of cells under nutrient starvation for 36 h in the presence or absence of Met. Green- and yellow-colored arrows indicate healthy and damaged mitochondria, respectively. Scale bar: 500 nm.
