Determination of mitochondrial fragmentation and autophagosome formation in C2C12 skeletal muscle cells

Aim: To investigate the effect of carbonyl cyanide 3-chlorophenylhydrazone (CCCP) on mitochondrial elimination in C2C12 skeletal muscle cells. Materials and methods: C2C12 muscle cells stably expressing Mito-DsRed were treated with DMSO or CCCP at the doses of 10, 20, and 30 mu M for 3, 6, and 24 h. After specific treatments, cells were fixed in 4% paraformaldehyde and immunocytochemistry assays were performed using appropriate antibodies to evaluate mitochondrial morphology and autophagosome formation. Total cell lysates were used for western blot assays. Results: CCCP induces mitochondrial fragmentation in C2C12 cells. In response to a mitochondrial uncoupler, endogenous autophagosome formation is significantly increased (P < 0.001). Co-localization analyses of confocal images indicate that fragmented mitochondria undergo engulfment by autophagosomes. Conclusion: The findings of this study will enhance our understanding of the mitophagic process in C2C12 skeletal muscle cells in order to identify molecular mechanisms governing removal of dysfunctional mitochondria.