Mitophagy is primarily due to alternative autophagy and requires the MAPK1 and MAPK14 signaling pathways

Yuko Hirota, Shun ichi Yamashita, Yusuke Kurihara, Xiulian Jin, Masamune Aihara, Tetsu Saigusa, Dongchon Kang, Tomotake Kanki

Research output: Contribution to journalArticlepeer-review

157 Citations (Scopus)


In cultured cells, not many mitochondria are degraded by mitophagy induced by physiological cellular stress. We observed mitophagy in HeLa cells using a method that relies on the pH-sensitive fluorescent protein Keima. With this approach, we found that mitophagy was barely induced by carbonyl cyanide m-chlorophenyl hydrazone treatment, which is widely used as an inducer of PARK2/Parkin-related mitophagy, whereas a small but modest amount of mitochondria were degraded by mitophagy under conditions of starvation or hypoxia. Mitophagy induced by starvation or hypoxia was marginally suppressed by knockdown of ATG7 and ATG12, or MAP1LC3B, which are essential for conventional macroautophagy. In addition, mitophagy was efficiently induced in Atg5 knockout mouse embryonic fibroblasts. However, knockdown of RAB9A and RAB9B, which are essential for alternative autophagy, but not conventional macroautophagy, severely suppressed mitophagy. Finally, we found that the MAPKs MAPK1/ERK2 and MAPK14/p38 were required for mitophagy. Based on these findings, we conclude that mitophagy in mammalian cells predominantly occurs through an alternative autophagy pathway, requiring the MAPK1 and MAPK14 signaling pathways.

Original languageEnglish
Pages (from-to)332-343
Number of pages12
Issue number2
Publication statusPublished - 2015

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology


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