Mitochondrial Hyperfusion Promotes Caspase 8 Dependent Cell Death.

<p>(A-C) U2OS cells were transfected with control (black), Drp1 (green), or Mff (red) siRNA for 96 hours. Cells were collected and stained for (A) cleaved caspase 3 or (B) cleaved caspase 8. Positivity of cleaved caspase 3 or 8 is indicated by an increase in fluorescence on the FACS histogram compared to control. (C) U2OS cells transfected with control, Drp1, or Mff siRNAs were treated with pan caspase inhibitor, zVAD (20 μM; dark gray bars), or the necroptosis inhibitor, necrostatin (10 μM; light gray bars), or vehicle (DMSO; black bars) every 24 hours for 96 hours following transfection. Cells were stained with propidium iodide (PI) and percent PI positivity was used as a marker of cell death. Error bars represent standard deviation from two replicate experiments where at least 10,000 events were collected for each treatment.