Mitochondrial Fusion and Apoptosis

Mitochondrial fusion is essential for maintaining genomic stability and physiological functions of mitochondria. Since mitochondrial fusion and fission work in synergy to regulate mitochondrial morphology and functions, it has been challenging to quantitatively measure the direct roles of mitochondrial fusion in apoptosis and cancer progression. Here, a high-throughput in vitro method to quantify mitochondrial fusion through single mitochondria analysis by the Flow NanoAnalyzer was reported. 

Isolated mitochondria expressing green fluorescent protein (GFP-mito) or Discosoma red fluorescent protein (DsRed-mito) were mixed together, induced to fuse, and analyzed by the Flow NanoAnalyzer. An individual particle simultaneously exhibiting green and red fluorescence was identified as an event of heterotypic fusion, and the efficiency of heterotypic fusion was used as a surrogate for overall fusion efficiency. The as-developed method was applied to reveal the interplay between mitochondrial fusion and apoptosis without the interference of fission. The data suggests that disruption of mitochondrial fusion could be a potent strategy for cancer therapy. Furthermore, the as-developed method offers an effective approach to identify fusion inhibitors, including betulinic acid and antimycin A, providing reasons for their powerful utility in cancer treatment.

Figure 1. Analysis of the effect of mitochondrial fusion on cell apoptosis by the Flow NanoAnalyzer and comparison of the fusion effects of different compounds.

Fusion was promoted by cytosol derived from healthy cells but inhibited by cytosolic apoptotic pathways. Mitochondrial fusion could inhibit apoptosis by delaying the collapse of mitochondrial membrane potential. Thus, disruption of mitochondrial fusion could be an efficient strategy in cancer therapy.

Talanta, 2020, 222, 121523.