Archives of Toxicology

, Volume 88, Issue 2, pp 323–336

ERK pathway is activated in bare-FeNPs-induced autophagy

Molecular Toxicology

DOI: 10.1007/s00204-013-1134-1

Cite this article as:
Park, EJ., Umh, H.N., Kim, SW. et al. Arch Toxicol (2014) 88: 323. doi:10.1007/s00204-013-1134-1


Iron oxide nanoparticles (FeNPs) are known to be one of the most biocompatible and safe nanoparticles. However, their long-term persistence remains a problem, and macrophages play as an important mediator in continuous stimulation of the immune system due to biopersistence of nanoparticles. In the present study, we identified the mechanisms underlying the uptake and toxicity of bare-FeNPs using RAW264.7 cells, a mouse peritoneal macrophage cell line. The bare-FeNPs penetrated the cell membrane through electrostatic interactions together with the general phagocytic pathway. At 24 h after exposure, they distributed freely in the cytosol or within autophagosome-like vacuoles. Bare-FeNPs induced decrease in the cell viability along with the cell cycle arrest in G1 phase. In addition, they increased the generation of ROS and the secretion of NO and TNF alpha as well as the expression of SOD-1 and SOD-2 proteins, which are an antioxidant. While the mitochondrial calcium level, the intensity of labeled mitochondria, and ATP production decreased, the levels of autophagy-related proteins such as p62, beclin 1, ATG5, and LC3B increased in a dose-dependent manner together with the levels of ATF 3, p-EGFR, and p-ERK proteins. However, the level of p-JNK protein clearly decreased. TEM images also showed that damaged organelle exist within autophagosome-like vacuoles with bare-FeNPs. On the basis of these results, we suggest that bare-FeNPs induce autophagy by initiating oxidative stress in RAW264.7 cells. Furthermore, ERK, but not JNK, pathway is activated in bare-FeNPs-induced autophagy.


Iron oxide nanoparticlesMacrophageAutophagyERKMitochondria

Supplementary material

204_2013_1134_MOESM1_ESM.ppt (408 kb)
EDS analysis of cell exposed to bare-FeNPs. (a) bright field and (b) dark field, and (d) EDS spectra of star point in TEM image (PPT 408 kb)
204_2013_1134_MOESM2_ESM.docx (21 kb)
Supplementary material 2 (DOCX 21 kb)
204_2013_1134_MOESM3_ESM.ppt (264 kb)
Decrease in pH following bare-FeNPs exposure. The pH value in cell culture media was measured within maximum 5 min after incubation finishing. The experiment was performed three times, independently, and the value means AV ± SD (PPT 263 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Department of Molecular Science and TechnologyAjou UniversitySuwonKorea
  2. 2.Department of Chemical EngineeringKwangwoon UniversitySeoulKorea
  3. 3.College of Veterinary MedicineSeoul National UniversitySeoulKorea
  4. 4.Department of Nano Fusion Technology, Graduate School of Convergence Science and TechnologySeoul National UniversitySuwonKorea
  5. 5.Graduate Group of Tumor BiologySeoul National UniversitySeoulKorea
  6. 6.Advanced Institute of Convergence TechnologySeoul National UniversitySuwonKorea