title: Magnetic iron oxide nanoparticles induce autophagy preceding apoptosis through mitochondrial damage and ER stress in RAW264.7 cells.
abstract: Magnetic nanoparticles have been widely used in a broad range of disciplines owing to their unique properties. However, many unexpected risks have been reported in their use. In this study, we investigated the uptake process and toxic mechanism of magnetic iron oxide nanoparticles (M-FeNPs) using RAW264.7 cells, a murine peritoneal macrophage cell line. M-FeNPs markedly enhanced the mobility of cells. At 24h after exposure, M-FeNPs were located freely in the cytosol or within autolysosomes containing various organelles, especially the endoplasmic reticulum (ER). Cell viability decreased in a dose-dependent manner in conjunction with the arrest in S phase. ATP production also rapidly decreased together with mitochondrial damage, the number of cells that generate ROS increased, and the secretions of pro-inflammatory cytokines enhanced. The levels of oxidative stress- and ER stress-related genes were up-regulated, whereas the levels of transcription-related genes were down-regulated. Additionally, the levels of autophagy- and ER stress-related proteins increased, and the number of apoptotic cells increased with time. We also investigated the function of the autolysosome in the cellular response after exposure of M-FeNPs. When cells were exposed to M-FeNPs for 24h with BaFA1 pretreatment, the plasma membrane disintegrated, cytosolic components disappeared, and the number of apoptotic cells significantly increased. Taken together, these results show that M-FeNPs induce autophagy preceding apoptosis through mitochondrial dysfunction and ER stress in RAW264.7 cells. Furthermore, blocking of autolysosome formation may accelerate apoptotic cell death and ER stress.
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Republic of Korea. Electronic address: pejtoxic@hanmail.net.
authors.forename: Eun-Jung
authors.initials: EJ
authors.lastname: Park
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Republic of Korea.
authors.forename: Dong-Hyuk
authors.initials: DH
authors.lastname: Choi
authors.affiliation: Department of Chemical Engineering, Kwangwoon University, Seoul 139-701, Republic of Korea.
authors.forename: Younghun
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea.
authors.forename: Eun-Woo
authors.initials: EW
authors.lastname: Lee
authors.affiliation: Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea.
authors.forename: Jaewhan
authors.initials: J
authors.lastname: Song
authors.affiliation: College of Veterinary Medicine, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Myung-Haing
authors.initials: MH
authors.lastname: Cho
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Republic of Korea.
authors.forename: Jae-Ho
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Republic of Korea.
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Kim
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D005290:Ferric Compounds / Q000633:toxicity*; D015870:Gene Expression / Q000187:drug effects; D008247:Lysosomes / Q000502:physiology; D053768:Metal Nanoparticles / Q000633:toxicity*; D051379:Mice; D008928:Mitochondria / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D005290:Ferric Compounds; D017382:Reactive Oxygen Species; C000499:ferric oxide
keywords: Apoptosis; Autophagy; ER stress; ER-phagy; Iron nanoparticles; Macrophages