title: The NADPH oxidase pathway is dysregulated by the P2X7 receptor in the SOD1-G93A microglia model of amyotrophic lateral sclerosis.
abstract: Inflammation and oxidative stress are thought to play determinant roles in the pathogenesis of amyotrophic lateral sclerosis (ALS). Degenerating motor neurons produce signals that activate microglia to release reactive oxygen species (ROS) and proinflammatory cytokines, resulting in a vicious cycle of neurodegeneration. The ALS-causing mutant protein Cu(+)/Zn(+) superoxide dismutase SOD1-G93A directly enhances the activity of the main ROS-producing enzyme in microglia, NADPH oxidase 2 (NOX2), a well-known player in the pathogenesis of ALS. Considering that extracellular ATP through P2X7 receptor constitutes a neuron-to-microglia alarm signal implicated in ALS pathology, we used primary microglial cells derived from transgenic SOD1-G93A mice and SOD1-G93A mice lacking the P2X7 receptor to investigate the effects of both pharmacological induction and genetic ablation of receptor activity on the NOX2 pathway. We observed that, in SOD1-G93A microglia, the stimulation of P2X7 receptor by 2'-3'-O-(benzoyl-benzoyl) ATP enhanced NOX2 activity in terms of translocation of p67(phox) to the membrane and ROS production; this effect was totally dependent on Rac1. We also found that, following P2X7 receptor stimulation, the phosphorylation of ERK1/2 was augmented in ALS microglia, and there was a mutual dependency between the NOX2 and ERK1/2 pathways. All of these microglia-mediated damaging mechanisms were prevented by knocking out P2X7 receptor and by the use of specific antagonists. These findings suggest a noxious mechanism by which P2X7 receptor leads to enhanced oxidative stress in ALS microglia and identify the P2X7 receptor as a promising target for the development of therapeutic strategies to slow down the progression of ALS.
authors.affiliation: Cellular Biology and Neurobiology Institute, National Research Council, Rome 00143, Italy.
authors.forename: Savina
authors.initials: S
authors.lastname: Apolloni
authors.forename: Chiara
authors.initials: C
authors.lastname: Parisi
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Pesaresi
authors.forename: Simona
authors.initials: S
authors.lastname: Rossi
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Carrì
authors.forename: Mauro
authors.initials: M
authors.lastname: Cozzolino
authors.forename: Cinzia
authors.initials: C
authors.lastname: Volonté
authors.forename: Nadia
authors.initials: N
authors.lastname: D'Ambrosi
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000690:Amyotrophic Lateral Sclerosis / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007249:Inflammation; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D017628:Microglia / Q000378:metabolism*; D009046:Motor Neurons / Q000378:metabolism; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism; D018384:Oxidative Stress; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D017382:Reactive Oxygen Species; D058486:Receptors, Purinergic P2X7 / Q000235:genetics / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D013777:Tetrazoles / Q000494:pharmacology; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020830:rac1 GTP-Binding Protein
chemical_list: C523668:3-(5-(2,3-dichlorophenyl)-1H-tetrazol-1-yl)methylpyridine; C545178:A-839977; D016207:Cytokines; D008562:Membrane Glycoproteins; D009479:Neuropeptides; D010750:Phosphoproteins; D058920:Purinergic P2X Receptor Antagonists; D011725:Pyridines; C484602:Rac1 protein, mouse; D017382:Reactive Oxygen Species; D058486:Receptors, Purinergic P2X7; D013777:Tetrazoles; C079789:neutrophil cytosol factor 67K; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; D000255:Adenosine Triphosphate; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D048049:Extracellular Signal-Regulated MAP Kinases; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein