Mitochondrial division is associated with autophagosome formation during mitophagy

Identification: Yamashita, Shun-ichi



Mitochondrial division is associated with autophagosome formation during mitophagy
Shun-ichi Yamashita1, Tomotake Kanki1
1Department of Cellular Physiology, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
Mitophagy, an autophagy specific for mitochondria, may contribute to maintaining mitochondria quality control. During mitophagy, it has been believed that a damaged portion of mitochondria is first divided from healthy mitochondria, and then it is recognized by autophagy machinery. Dynamin-related protein 1 (Drp1) plays a pivotal role for mitochondrial division, thus implying Drp1 is also required for mitophagy. However, the contribution of Drp1 to mitophagy remains controversial.
To elucidate this issue, we examined mitochondrial morphology in Drp1 knockout (KO) cells upon mitophagy. Autophagosomes containing small fragmented mitochondria were observed both in WT and Drp1 KO cells upon mitophagy. These results suggest that mitochondria can be divided in Drp1 KO cells. To further examine how mitochondria are divided in Drp1 KO cells, we performed time-lapse imaging using GFP-LC3 and mito-mCherry. After induction of mitophagy, GFP-LC3 signals were first emerged on tubular mitochondria, and then mitochondrial portion was divided at the site simultaneously with isolation membrane elongation. Taken together, these results suggest that mitochondria are divided from tubular mitochondria simultaneously with autophagosome formation but independently of Drp1 during mitophagy.
Yamashita SI et al., 2016. J Cell Biol. 215:649-665.



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