A dual role of transient receptor potential melastatin 2 channel in cytotoxicity induced by silica nanoparticles.

Peilin Yu,Zunquan Zhao,Yifan Zheng,Xinqiang Zhu,Jin Li,Daishun Ling,Jun Zhang,Wei Yang,Zhaoyuan Hui,Lie Wang,Lin-Hua Jiang,Jialin Jiang,Jianhong Luo

doi:10.1038/srep18171

Abstract

Silica nanoparticles (NPs) have remarkable applications. However, accumulating evidence suggests NPs can cause cellular toxicity by inducing ROS production and increasing intracellular Ca2+ ([Ca2+]i), but the underlying molecular mechanism is largely unknown. Transient receptor potential melastatin 2 (TRPM2) channel is known to be a cellular redox potential sensor that provides an important pathway for increasing the [Ca2+]i under oxidative stress. In this study, we examined the role of TRPM2 channel in silica NPs-induced oxidative stress and cell death. By quantitation of cell viability, ROS production, [Ca2+]i, and protein identification, we showed that TRPM2 channel is required for ROS production and Ca2+ increase induced by silica NPs through regulating NADPH oxidase activity in HEK293 cells. Strikingly, HEK293 cells expressing low levels of TRPM2 were more susceptible to silica NPs than those expressing high levels of TRPM2. Macrophages from young mice showed significantly lower TRPM2 expression than those from senescent mice and had significantly lower viability after silica NPs exposure than those from senescent ones. Taken together, these findings demonstrate for the first time that TRPM2 channel acts as an oxidative stress sensor that plays a dual role in silica NPs-induced cytotoxicity by differentially regulating the NADPH oxidase activity and ROS generation.

Highlights

TRPM2 expression than those from senescent mice and had significantly lower viability after silica NPs exposure than those from senescent ones
1) TRPM2 channels are required for silica NPs-induced cytotoxicity; 2) The expression level of TRPM2 channels is critical in conferring susceptibility to silica NPs-induced cell death (Fig. 1); 3) silica NPs-induced reactive oxygen species (ROS) production and increase in the [Ca2+]i depend on the expression level of TRPM2 channels that bi-directionally regulates the activity of NADPH oxidase (Figs 2–4); and 4) exposure to both 30 and 100 μ g/mL silica NPs for 6 h reduced the viability of Bone marrow-derived macrophages (BMDMs), the viability of BMDMs from the young mice was much lower than in those from senescent mice, and this was correlated with the TRPM2 expression levels (Fig. 5), as seen in HEK293
By using several ROS scavengers (NAC, sodium L-ascorbate (SA), and diphenylenelodonium chloride (DPI)), we found that all of these compounds prevented the ROS production induced by silica NPs in the TRPM2-LE cells, indicating that the NADPH oxidase complex is mainly responsible for the ROS generation that leads to cell death (Figs 2 and 3)

Summary

Introduction

TRPM2 expression than those from senescent mice and had significantly lower viability after silica NPs exposure than those from senescent ones Taken together, these findings demonstrate for the first time that TRPM2 channel acts as an oxidative stress sensor that plays a dual role in silica NPs-induced cytotoxicity by differentially regulating the NADPH oxidase activity and ROS generation. Recent studies have shown that the TRPM2 channel forms a Ca2+-permeable cationic channel activated by intracellular ADP-ribose (ADPR), H2O2, and ROS9–12, indicating that it serves as a cellular redox potential sensor This channel provides an important pathway for oxidative stress-induced increases in the intracellular Ca2+ concentrations ([Ca2+]i) in many cell types[13]. Expression of the subunits of NADPH oxidase, which is responsible for silica NPs-induced ROS generation, was examined

Methods

Results

Conclusion