Chapter 16 Monitoring Mitochondrial Dynamics with Photoactivateable Green Fluorescent Protein

Mitochondria are dynamic organelles that undergo continuous cycles of fusion and fission. Monitoring and quantification of mitochondrial dynamics has proved to be challenging because these processes are distinctly different from movement and apposition. While the majority of contact events do not lead to fusion, fission can occur without translocation, leaving the two mitochondria juxtaposed. The advent of photoactivateable fluorescent proteins has enabled researchers to distinguish mitochondrial fusion and fission. These genetically encoded fluorophores can be targeted to the mitochondrial compartments of interest to visualize how these intermix and segregate between dynamic mitochondria over time. The PAGFPmt-based mitochondrial dynamics assay has proved to be a powerful technique for revealing the treatments and cellular processes that affect fusion and fission. By using this technique in combination with other parameters, such as measurements of mitochondrial membrane potential, we have begun to understand the processes that control fusion and fission as well as the significance of mitochondrial dynamics.