Atg5-dependent autophagy plays a protective role against methylmercury-induced cytotoxicity.
Methylmercury (MeHg) is a widespread environmental pollutant and causes a serious hazard to health worldwide. However, molecular mechanisms underlying MeHg toxicity remain elusive. We show that MeHg reduced mouse embryonic fibroblast (MEF) viability in a dose-dependent manner. Furthermore, MeHg treatment increased levels of autophagy markers LC3-II and p62, possibly by acting on the MAPKs signaling pathway in several cell types. MeHg exposure elevated the number of LC3 puncta in stable GFP-LC3 MEFs and the number of autophagic vacuoles. The accumulation of LC3-II and p62 increased further when complementing MeHg with autophagy inhibitor, chloroquine. Moreover, we found that autophagy-related gene 5-deficient (Atg5-/-) MEFs exhibited higher sensitivity and higher levels of p62 compared to their wild-type counterparts following MeHg exposure. This suggested that p62 was upregulated at the transcription level by MeHg and degraded by Atg5-dependent autophagy. Our data demonstrate that MeHg exposure promotes autophagy, and Atg5-dependent autophagy serves to protect cells from MeHg cytotoxicity.
Department of Public Health and Molecular Toxicology, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan. Electronic address: takanezaway@pharm.kitasato-u.ac.jp.
Yasukazu
Y
Takanezawa
Department of Public Health and Molecular Toxicology, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
Ryosuke
R
Nakamura
Department of Public Health and Molecular Toxicology, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
Yuka
Y
Sone
Department of Public Health and Molecular Toxicology, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
Shimpei
S
Uraguchi
Department of Public Health and Molecular Toxicology, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
Masako
M
Kiyono
D000818:Animals; D001343:Autophagy / Q000235:genetics*; D000071187:Autophagy-Related Protein 5 / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D002738:Chloroquine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D055786:Gene Knockout Techniques; D008767:Methylmercury Compounds / Q000633:toxicity*; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010588:Phagosomes / Q000187:drug effects / Q000378:metabolism; D000071456:Sequestosome-1 Protein / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
C495773:Atg5 protein, mouse; D000071187:Autophagy-Related Protein 5; C480860:Map1lc3b protein, mouse; D008767:Methylmercury Compounds; D008869:Microtubule-Associated Proteins; D000071456:Sequestosome-1 Protein; D002738:Chloroquine; D020928:Mitogen-Activated Protein Kinases
Atg5; Autophagy; LC3; Methylmercury; p62