FIGURE 5:

Drp1 Ser 579 phosphorylation promotes fission activity. SH-SY5Y cells were transfected with control (Con siRNA) and Drp1 siRNA for 48 h. Cells were then transfected with the plasmids of control, wild-type Drp1 (Drp1^wt), or mutant Drp1 at Ser 579 (Drp1^S579A) for 24 h. (A) Top: Control and cells treated with H₂O₂ (200 μM) or Ang II (1 μM) for 6 h after cells were transfected with control siRNA followed by control vector. The cells were stained with antibodies of Tom20 (green), a mitochondrial marker, and Drp1 (red) and Hoechst nuclear stain (blue). Bottom: Drp1 knockdown was confirmed by staining with anti-Drp1 antibody (top). Tom20 and nuclei were stained as in the left panel. The cells in which endogenous Drp1 was replaced with wild-type (Drp1^wt) or Ser 579 mutant (Drp1^S579A) are outlined with a dashed line. Arrow shows the cells transfected by only Drp1 siRNA. Scale bar is 0.5 μm. Enlarged mitochondrial network is shown in the yellow box, underneath each panel. (B) Histogram: The percentage of cells with fragmented mitochondria relative to the total number of cells is presented as the mean ± SE of three independent experiments. At least 200 cells per group were counted. *p < 0.05.