Figure 8. Activation of Drp1 by E2F5‐Drp1 complex enhances HPV‐E7/ceramide‐mediated lethal mitophagy.

• A
  Top computer‐generated model of E2F5 (orange)‐Drp1 (gray) docking is shown, with the first and last residues of the known dimerization domain of E2F5 indicated, including residues 85 and 177 (left panel). Models of GFP‐tagged wild‐type E2F5 (E2F5^WT) and dimerization domain deleted mutant of E2F5 (E2F5^Δ85–177) are shown (right panel).
• B
  UM‐SCC22A cells transfected with E2F5^WT‐GFP or E2F5^Δ84–177‐GFP were used for PLA to measure their association of RB using labeled anti‐RB and anti‐GFP antibodies in response to C₁₈‐pyr‐cer (10 μM, 1 h). PLA images (scale bars represent 100 μm) were quantified using the PLA software as described by the manufacturer. Data are means ± SD from three independent experiments, analyzed by unpaired Student's t‐test (n = 3, *P = 0.0049, **P = 0.00031).
• C–E
  UM‐SCC22A cells expressing vector, E2F5^WT or mutant E2F5^Δ85–177, were used for the measurement of Drp1‐E2F5 association in the absence/presence of C₁₈‐pyr‐cer (10 μM, 1 h) using PLA (C) compared to vector‐transfected controls. Transfection efficiency and abundance of ectopically expressed E2F5^WT‐GFP and mutant E2F5^Δ85–177‐GFP were detected by immunofluorescence (scale bars represent 100 μm). Vector‐GFP was used as a control (right panel, C). Moreover, effects of E2F5^WT versus mutant E2F5^Δ85–177 on cell death or mitophagy in response to C₁₈‐pyr‐cer (20 μM, 48 h) were measured by trypan blue exclusion assay (D) or by live cell imaging confocal micrographs (E) of UM‐SCC‐22A cells stained with LTR and MTDR (MitoTracker deep red, imaged with blue channel, and colored green for imaging). Images were quantified using ImageJ (scale bars represent 100 μm). Data are means ± SD from three independent experiments, analyzed by unpaired Student's t‐test (C and E, n = 3, *P = 0.011, **P = 0.0025) or two‐way ANOVA (D, n = 3, *P = 0.0142, **P = 1.6 × 10⁻⁸).