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Epigenetic modulation upon exposure of lung fibroblasts to TiO2 and ZnO nanoparticles: alterations in DNA methylation

Authors Patil N, Gade WN, Deobagkar DD

Received 12 April 2016

Accepted for publication 1 June 2016

Published 7 September 2016 Volume 2016:11 Pages 4509—4519


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 2

Editor who approved publication: Prof. Dr. Thomas Webster

Nayana A Patil,1,2 WN Gade,2 Deepti D Deobagkar1

1Department of Zoology, Molecular Biology Research Laboratory, Centre of Advanced Studies, 2Department of Biotechnology, Proteomic Research Laboratory, Savitribai Phule Pune University, Pune, India

Abstract: Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) are promising candidates for numerous applications in consumer products. This will lead to increased human exposure, thus posing a threat to human health. Both these types of NPs have been studied for their cell toxicity, immunotoxicity, and genotoxicity. However, effects of these NPs on epigenetic modulations have not been studied. Epigenetics is an important link in the genotype and phenotype modulation and misregulation can often lead to lifestyle diseases. In this study, we have evaluated the DNA methylation-based epigenetic changes upon exposure to various concentrations of NPs. The investigation was designed to evaluate global DNA methylation, estimating the corresponding methyltransferase activity and expression of Dnmt gene using lung fibroblast (MRC5) cell line as lungs are the primary route of entry and target of occupational exposure to TiO2 and ZnO NPs. Enzyme-linked immunosorbent assay-based immunochemical assay revealed dose-related decrease in global DNA methylation and DNA methyltransferase activity. We also found direct correlation between the concentration of NPs, global methylation levels, and expression levels of Dnmt1, 3A, and 3B genes upon exposure. This is the first study to investigate effect of exposure to TiO2 and ZnO on DNA methylation levels in MRC5 cells. Epigenetic processes are known to play an important role in reprogramming and adaptation ability of an organism and can have long-term consequences. We suggest that changes in DNA methylation can serve as good biomarkers for early exposure to NPs since they occur at concentrations well below the sublethal levels. Our results demonstrate a clear epigenetic alteration in response to metal oxide NPs and that this effect was dose-dependent.

Keywords: nanotoxicity, epigenetics, global DNA methylation, 5-mC, DNA methyltransferase, Dnmt

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