Cytotoxicity of paraquat in microglial cells: Involvement of PKCdelta- and ERK1/2-dependent NADPH oxidase.
Excess production of reactive oxygen species (ROS) is an important mechanism underlying the pathogenesis of a number of neurodegenerative diseases including Parkinson's disease (PD) which is characterized by a progressive loss of dopaminergic neurons in the substantia nigra. Exposure to paraquat, an herbicide with structure similar to the dopaminergic neurotoxin, 1-methyl-4-phenylpyridinium (MPP+), has been shown to produce PD-like symptoms. Despite previous focus on the dopaminergic neurons and signaling pathways involved in their cell death, recent studies have implicated microglial cells as a major producer of ROS for damaging neighboring neurons. In this study, we examined the source of ROS and the underlying signaling pathway for paraquat-induced cytotoxicity to BV-2 microglial cells. Paraquat-induced ROS production (including superoxide anions) in BV-2 cells was accompanied by translocation of the p67phox cytosolic subunit of NADPH oxidase to the membrane. Paraquat-induced ROS production was inhibited by NADPH oxidase inhibitors, apocynin and diphenylene iodonium (DPI), but not the xanthine/xanthine oxidase inhibitor, allopurinol. Apocynin and DPI also rescued cells from paraquat-induced toxicity. The inhibitors for protein kinase C delta (PKCdelta) or extracellular signal-regulated kinases (ERK1/2) could partially attenuate paraquat-induced ROS production and cell death. Rottlerin, a selective PKCdelta inhibitor, also inhibited paraquat-induced translocation of p67phox. Taken together, this study demonstrates the involvement of ROS from NADPH oxidase in mediating paraquat cytotoxicity in BV-2 microglial cells and this process is mediated through PKCdelta- and ERK-dependent pathways.
Miller
Rebecca L
RL
Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65211, USA.
Sun
Grace Y
GY
Sun
Albert Y
AY
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000201:enzymology / Q000503:physiopathology; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects* / Q000378:metabolism; D006540:Herbicides / Q000633:toxicity; D051379:Mice; D017628:Microglia / Q000187:drug effects* / Q000201:enzymology; D019255:NADPH Oxidases / Q000187:drug effects* / Q000378:metabolism; D009410:Nerve Degeneration / Q000139:chemically induced / Q000201:enzymology / Q000503:physiopathology; D009498:Neurotoxins / Q000633:toxicity; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010269:Paraquat / Q000633:toxicity*; D010300:Parkinson Disease / Q000201:enzymology / Q000209:etiology / Q000503:physiopathology; D010750:Phosphoproteins / Q000187:drug effects / Q000378:metabolism; D051745:Protein Kinase C-delta / Q000187:drug effects* / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D004791:Enzyme Inhibitors; D006540:Herbicides; D009498:Neurotoxins; D010750:Phosphoproteins; D017382:Reactive Oxygen Species; C079789:neutrophil cytosol factor 67K; D019255:NADPH Oxidases; D051745:Protein Kinase C-delta; D048049:Extracellular Signal-Regulated MAP Kinases; D010269:Paraquat