Assessment of mitophagy in mt‐Keima Drosophila revealed an essential role of the PINK1‐Parkin pathway in mitophagy induction in vivo

Abstract

Mitophagy has been implicated in mitochondrial quality control and in various human diseases. However, the study of in vivo mitophagy remains limited. We previously explored in vivo mitophagy using a transgenic mouse expressing the mitochondria‐targeted fluorescent protein Keima (mt‐Keima). Here, we generated mt‐Keima Drosophila to extend our efforts to study mitophagy in vivo. A series of experiments confirmed that mitophagy can be faithfully and quantitatively measured in mt‐Keima Drosophila. We also showed that alterations in mitophagy upon environmental and genetic perturbation can be measured in mt‐Keima Drosophila. Analysis of different tissues revealed a variation in basal mitophagy levels in Drosophila tissues. In addition, we found a significant increase in mitophagy levels during Drosophila embryogenesis. Importantly, loss‐of‐function genetic analysis demonstrated that the phosphatase and tensin homolog‐induced putative kinase 1 (PINK1)‐Parkin pathway is essential for the induction of mitophagy in vivo in response to hypoxic exposure and rotenone treatment. These studies showed that the mt‐Keima Drosophila system is a useful tool for understanding the role and molecular mechanism of mitophagy in vivo. In addition, we demonstrated the essential role of the PINK1‐Parkin pathway in mitophagy induction in response to mitochondrial dysfunction.—Kim, Y. Y., Um, J.‐H., Yoon, J.‐H., Kim, H., Lee, D.‐Y., Lee, Y. J., Jee, H. J., Kim, Y. M., Jang, J. S., Jang, Y.‐G., Chung, J., Park, H. T., Finkel, T., Koh, H., Yun, J. Assessment of mitophagy in mt‐Keima Drosophila revealed an essential role of the PINK1‐Parkin pathway in mitophagy induction in vivo. FASEB J. 33, 9742–9751 (2019). http://www.fasebj.org

PINK1 alleviates thermal hypersensitivity in a paclitaxel-induced Drosophila model of peripheral neuropathy

“…Jan (University of California, San Francisco, CA). The UAS-mt-Keima line was generated previously [19]. The UAS-PINK1 and PINK1 RNAi lines were generated previously [16].…”

Autophagy in the mammalian nervous system: a primer for neuroscientists

“…Recent Drosophila studies also support the notion that PINK1-Parkin signalling is dispensable for basal mitophagy, but may also play a role in stress-induced mitophagy [126,127]. Independent of mitophagy, other studies have delineated the mechanics of how matrix-localised mtDNA can activate cGAS-STING signalling [163], and have also linked cGAS-STING signalling to macroautophagy [164].…”

“…Additionally, microglia and cerebral vasculature also had noticeably high levels of mitochondrial turnover [122]. Recent data utilising these reporters also demonstrated the conservation of basal mitophagy from mammals to flies [126,127].…”

PINK1 and Parkin mitochondrial quality control: a source of regional vulnerability in Parkinson’s disease

“…However, the effects on mitochondrial protein half-lives were only weakly correlated between the two mutants, suggesting either that mitophagy may be influenced by Parkinindependent regulatory pathways or that Parkin may regulate mitochondrial protein turnover through autophagyindependent mechanisms [107]. Moreover, three of the previously mentioned studies found that PINK1 and Parkin knockouts had no effect on basal mitophagy in mouse and Drosophila [103][104][105], whereas one study found that PINK1 or Parkin deficiency in Drosophila abrogated an age-dependent increase in basal mitophagy [106]. Furthermore, if driving mitophagy is a primary role of endogenous Parkin/PINK1, then one might expect that loss of either gene would lead to accumulation of mitochondria.…”

“…A few recent studies using mitochondria-targeted pHsensitive fluorescent indicators suggest that low levels of basal mitophagy occur throughout both wild-type mouse and Drosophila brains, including in DA neurons [101][102][103][104][105][106]. The rate of basal mitophagy appears to increase with the metabolic demands of the tissue and in response to stressors such as hypoxia and mtDNA mutagenic stress [102,104,106].…”