Mitochondrial fragmentation is required for PMR. (A) Images showing mitochondrial shape before and after PM injury in MFN DKO MEFs. Dotted red box marks the magnified region on the right. (B) FM 1-43 dye intensity after injury to WT (n = 56) and MFN DKO MEFs (n = 37). (C) Percentage of cells that failed to repair in independent experiments (n = 6 experiments). (D) Kinetics of Lifeact-mCherry at injury site in MFN DKO MEFs (n = 4). (E) Maximal Lifeact-mCherry intensity after injury in WT (n = 3) and MFN DKO (n = 4) MEFs. (F) Images showing mitochondria near the site of PM injury in healthy control and MiD49 patient fibroblasts. (G) Plot quantifying mitochondrial fragmentation after injury in control (n = 21) and MiD49 patient fibroblasts (n = 28 cells). (H) FM 1-43 dye intensity after injury in control (n = 50) and MiD49 patient fibroblasts (n = 48 cells). (I) Percentage of cells that failed to repair (n = 5 experiments). (J) Lifeact-mCherry intensity after PM injury in control and MiD49 patient fibroblasts (n = 13 control and 19 MiD49 patient cells). Mitochondria are marked by MitoTracker Green. Arrows mark the site of injury. Scale bar = 10 µm (whole cell, A) and 5 µm (zoom, A and F). *, P < 0.05 by unpaired t test. #, P < 0.05 by Mann–Whitney U test. Error bars represent SEM.