Overexpression of Mfn1/Mfn2 and Drp1/Fis1 promotes mitochondrial fusion and fission in DM cybrid, respectively. Gene overexpression was conducted by the transfecting plasmid. GFP-expressing plasmid (vector) was used as vector control. (a) Abundance of dynamic proteins Mfn1, Mfn2, Drp1, and Fis1 was determined using Western blotting. β-Actin served as loading control. (b) Mitochondrial morphology was visualized by transfecting cox4-DsRed (red fluorescence) in DM cybrid expressing GFP alone or GFP-tagged mitochondrial dynamic proteins (green fluorescence). An enlarged segment of each image was shown by a lower right square. (c) The MicroP algorithm categorized mitochondrial morphology into six types: small globe (blue), large globe (yellow), simple tube (green), twisted tube (orange), donut (red), and branching tube (purple). N = 75–400 mitochondria from 15–30 cells and three independent experiments.