@article{c123c449d9754a3d886bdd215fb50a49,
title = "Ubiquitination and receptor-mediated mitophagy converge to eliminate oxidation-damaged mitochondria during hypoxia",
abstract = "The contribution of the Ubiquitin-Proteasome System (UPS) to mitophagy has been largely attributed to the E3 ubiquitin ligase Parkin. Here we show that in response to the oxidative stress associated with hypoxia or the hypoxia mimic CoCl2, the damaged and fragmented mitochondria are removed by Parkin-independent mitophagy. Mitochondria isolated from hypoxia or CoCl2-treated cells exhibited extensive ubiquitination, predominantly Lysine 48-linked and involves the degradation of key mitochondrial proteins such as the mitofusins MFN1/2, or the import channel component TOM20. Reflecting the critical role of mitochondrial protein degradation, proteasome inhibition blocked CoCl2-induced mitophagy. The five conserved ubiquitin-binding autophagy receptors (p62, NDP52, Optineurin, NBR1, TAX1BP1) were dispensable for the ensuing mitophagy, suggesting that the mitophagy step itself was independent of ubiquitination. Instead, the expression of two ubiquitin-independent mitophagy receptor proteins BNIP3 and NIX was induced by hypoxia or CoCl2-treatment followed by their recruitment to the oxidation-damaged mitochondria. By employing BNIP3/NIX double knockout and DRP1-null cell lines, we confirmed that mitochondrial clearance relies on DRP1-dependent mitochondrial fragmentation and BNIP3/NIX-mediated mitophagy. General antioxidants such as N-Acetyl Cysteine (NAC) or the mitochondria-specific Mitoquinone prevented HIF-1α stabilization, ameliorated hypoxia-related mitochondrial oxidative stress, and suppressed mitophagy. We conclude that the UPS and receptor-mediated autophagy converge to eliminate oxidation-damaged mitochondria.",
keywords = "HIF-1 alpha, HIF-1α, Hypoxia, Mitochondria, Mitophagy, Oxidative stress, Proteasome, Ubiquitin",
author = "P Sulkshane and J Ram and A Thakur and N Reis and O Kleifeld and MH Glickman",
note = "Funding Information: We sincerely thank Prof. Richard Youle and his team for kindly providing us the penta knockout (5KO) and DRP1 knockout HeLa cell lines, and Dr. Michael Lassarou for the mitokeima plasmid. We thank Dr. Nitsan Dahan and all members of the Microscopy and sorting units of the LS&E institute at the Technion for painstakingly aiding fluorescence microscopy and FACS. We thank all members of the Smoler Proteomics Center at the Technion for sample handling, and members of the Glickman lab for critical comments. This work was supported by a Technion Integrated Cancer Center (TICC) fellowship to PS, grant 755/19 from the Israel Science Foundation for studying ubiquitination at mitochondria (MHG), and a grant 76251-12-9/19 (ZN3457) with S. Dennerlein from the Ministry of Science and Culture of Lower Saxony for research on mitochondria (MHG). Funding Information: We sincerely thank Prof. Richard Youle and his team for kindly providing us the penta knockout (5KO) and DRP1 knockout HeLa cell lines, and Dr. Michael Lassarou for the mitokeima plasmid. We thank Dr. Nitsan Dahan and all members of the Microscopy and sorting units of the LS&E institute at the Technion for painstakingly aiding fluorescence microscopy and FACS. We thank all members of the Smoler Proteomics Center at the Technion for sample handling, and members of the Glickman lab for critical comments. This work was supported by a Technion Integrated Cancer Center (TICC) fellowship to PS, grant 755/19 from the Israel Science Foundation for studying ubiquitination at mitochondria (MHG), and a grant 76251-12-9/19 (ZN3457) with S. Dennerlein from the Ministry of Science and Culture of Lower Saxony for research on mitochondria (MHG). Publisher Copyright: {\textcopyright} 2021",
year = "2021",
month = sep,
doi = "https://doi.org/10.1016/j.redox.2021.102047",
language = "American English",
volume = "45",
journal = "Redox Biology",
issn = "2213-2317",
publisher = "Elsevier",
}