FIGURE 2.
Parkin promotes mitophagy but not autophagy induction. A, HeLa cells were transfected with mCherry-Parkin for 24 h and then treated with CCCP (30 μm) for 6 h. The cells were fixed and stained with anti-Tom20, followed by confocal microscopy. The cells marked with the yellow dotted ovals expressed no or low levels of Parkin and still had mitochondria, whereas cells marked with white solid ovals expressed a high level of Parkin and had no mitochondria. Bars, 20 μm. B, the percentage of cells with less or no mitochondria were quantified in Parkin-positive and -negative cells. *, p < 0.01, Z test. C, HEK 293-mCherry-Parkin cells were treated as indicated with CQ (10 μm) or bafilomycin A1 (BafA1, 100 nm). The percentages of cells with less or no mitochondria were quantified in Parkin-positive cells. *, p < 0.05, Z-test. Ctl, control. D, GFP-LC3-HeLa cells were transfected with mCherry-Parkin (red) for 24 h and then treated with CCCP (30 μm) for 6 h. The cells were fixed and immunostained for Tom20 (blue). Bars, 10 μm. Enlarged images from the boxed areas demonstrate the co-localization of Tom20 with GFP-LC3 and/or with Parkin. E, the number of GFP-LC3 dots that were co-localized with mitochondria was quantified in Parkin-positive and Parkin-negative cells. *, p < 0.01, one-way ANOVA. F, the total number of GFP-LC3 dots was quantified in Parkin-positive and -negative cells. *, p < 0.01. n.s., not significant (p > 0.05), one-way ANOVA. All of the data shown are the means ± S.D.