Manganese (II) chloride leads to dopaminergic neurotoxicity by promoting mitophagy through BNIP3-mediated oxidative stress in SH-SY5Y cells

Yanning Huang,Ruikang Mo,Jinfeng Huang,Qiaolin Wen,Man Luo,Jin Wang,Yousheng Xiao

doi:10.1186/s11658-021-00267-8

Abstract

BackgroundManganese overexposure can induce neurotoxicity, lead to manganism and result in clinical manifestations similar to those of parkinsonism. However, the underlying molecular mechanism is still unclear. This study demonstrated that MnCl2 induces mitophagy and leads to neurotoxicity by promoting BNIP3-mediated reactive oxygen species (ROS) generation.MethodsHuman neuroblastoma SH-SY5Y cells were used throughout our experiments. Cell viability was detected by cell proliferation/toxicity test kits. Mitochondrial membrane potential was measured by flow cytometry. ROS generation was detected using a microplate reader. Protein levels were evaluated by Western blot. Transmission electron microscopy was used to evaluate mitochondrial morphology. Co-immunoprecipitation was used to verify the interaction between BNIP3 and LC3.ResultsMnCl2 led to loss of mitochondrial membrane potential and apoptosis of SH-SY5Y cells by enhancing expression of BNIP3 and conversion of LC3-I to LC3-II. Moreover, MnCl2 reduced expression of the mitochondrial marker protein TOMM20 and promoted interaction between BNIP3 and LC3. The results also indicated that a decrease in BNIP3 expression reduced the mitochondrial membrane potential loss, attenuated apoptosis and reduced mitochondrial autophagosome formation in SH-SY5Y cells after MnCl2 treatment. Finally, we found that manganese-induced ROS generation could be reversed by the antioxidant N-acetyl cysteine (NAC) or silencing BNIP3 expression.ConclusionsBNIP3 mediates MnCl2-induced mitophagy and neurotoxicity in dopaminergic SH-SY5Y cells through ROS. Thus, BNIP3 contributes to manganese-induced neurotoxicity by functioning as a mitophagy receptor protein.

Highlights

Manganese overexposure can induce neurotoxicity, lead to manganism and result in clinical manifestations similar to those of parkinsonism
After 12 h, the inhibition of SH-SY5Y cells treated with different concentrations of M nCl2 was not significantly different from that of cells treated with the control treatment
The results showed that the mitochondrial membrane potential decreased in a concentration-dependent manner after treatment with 200, 400, and 800 μM Manganese(II) chloride (MnCl2) for 24 h (Fig. 1b)

Summary

Introduction

Manganese overexposure can induce neurotoxicity, lead to manganism and result in clinical manifestations similar to those of parkinsonism. It is generally agreed that the incidence of parkinsonism increases with aging and the presence of genetic factors and various environmental factors, including pesticides, insecticides, metals and other industrial chemicals [5, 6]. Some metals, such as iron, manganese, and copper, are present in our daily diet. Studies have shown that excessive exposure to manganese can affect multiple cellular processes, such as ROS generation [10], mitochondrial dysfunction [11], and autophagy [12], and lead to neurotoxicity [13]. Research on manganese exposure and its relevance to parkinsonism has increased annually, the underlying molecular mechanism is still unclear

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