Mechanical stretch exacerbates the cell death in SH-SY5Y cells exposed to paraquat: mitochondrial dysfunction and oxidative stress.
Recent studies suggest that traumatic brain injury (TBI) and pesticide exposure increase the risk of Parkinson's disease (PD), but the molecular mechanisms involved remain unclear. Using an in vitro model of TBI, we evaluated the role of mitochondrial membrane potential (ΔΨm) and mitochondrial reactive oxygen species (ROS) induced by stretch on dopaminergic cell death upon paraquat exposure. Human dopaminergic neuroblastoma SH-SY5Y cells grown on silicone membrane were stretched at mild (25%) and moderate (50%) strain prior to paraquat exposure. We observed that moderate stretch (50% strain) increased the vulnerability of cells to paraquat demonstrated by the loss of plasma membrane integrity (propidium iodide-uptake) and decreased mitochondrial activity (MTT assay). Mitochondrial depolarization occurred immediately after stretch, while mitochondrial ROS increased rapidly and remained elevated for up to 4h after the stretch injury. Intracellular glutathione (GSH) stores were also transiently decreased immediately after moderate stretch. Cells treated with paraquat, or moderate stretch exhibited negligible mitochondrial depolarization at 48h post treatment, whereas in cells stretched prior to paraquat exposure, a significant mitochondrial depolarization occurred compared to samples exposed to either paraquat or stretch. Moderate stretch also increased mitochondrial ROS formation, as well as exacerbated intracellular GSH loss induced by paraquat. Overexpression of manganese superoxide dismutase (MnSOD) markedly diminished the deleterious effects of stretch in paraquat neurotoxicity. Our findings demonstrate that oxidative stress induced by mitochondrial dysfunction plays a critical role in the synergistic toxic effects of stretch (TBI) and pesticide exposure. Mitigation of oxidative stress via mitochondria-targeted antioxidants appears an attractive route for treatment of neurodegeneration mediated by TBI.
Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu 210029, China; Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0526, USA.
Fang
F
Wang
Redox Biology Center & School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583-0905, USA.
Rodrigo
R
Franco
Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0526, USA.
Maciej
M
Skotak
Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu 210029, China. Electronic address: ghu@njmu.edu.cn.
Gang
G
Hu
Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ 07102-1982, USA. Electronic address: namas.chandra@njit.edu.
Namas
N
Chandra
D000256:Adenoviridae / Q000235:genetics; D000704:Analysis of Variance; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D005822:Genetic Vectors; D005978:Glutathione / Q000378:metabolism; D006540:Herbicides / Q000494:pharmacology*; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects*; D009447:Neuroblastoma / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects*; D010269:Paraquat / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013314:Stress, Mechanical; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors
D006540:Herbicides; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D005978:Glutathione; D010269:Paraquat
Mitochondria; MnSOD; Paraquat; Reactive oxygen species; Traumatic brain injury