title: Mitochondrial dysfunction is involved in P2X7 receptor-mediated neuronal cell death.
abstract: P2X7 receptor (P2X7R) is known to be a 'death receptor' in immune cells, but its functional expression in non-immune cells such as neurons is controversial. Here, we examined the involvement of P2X7R activation and mitochondrial dysfunction in ATP-induced neuronal death in cultured cortical neurons. In P2X7R- and pannexin-1-expressing neuron cultures, 5 or more mM ATP or 0.1 or more mM BzATP induced neuronal death including apoptosis, and cell death was prevented by oxATP, P2X7R-selective antagonists. ATP-treated neurons exhibited Ca(2+) entry and YO-PRO-1 uptake, the former being inhibited by oxATP and A438079, and the latter by oxATP and carbenoxolone, while P2X7R antagonism with oxATP, but not pannexin-1 blocking with carbenoxolone, prevented the ATP-induced neuronal death. The ATP treatment induced reactive oxygen species generation through activation of NADPH oxidase and activated poly(ADP-ribose) polymerase, but both of them made no or negligible contribution to the neuronal death. Rhodamine123 efflux from neuronal mitochondria was increased by the ATP-treatment and was inhibited by oxATP, and a mitochondrial permeability transition pore inhibitor, cyclosporine A, significantly decreased the ATP-induced neuronal death. In ATP-treated neurons, the cleavage of pro-caspase-3 was increased, and caspase inhibitors, Q-VD-OPh and Z-DEVD-FMK, inhibited the neuronal death. The cleavage of apoptosis-inducing factor was increased, and calpain inhibitors, MDL28170 and PD151746, inhibited the neuronal death. These findings suggested that P2X7R was functionally expressed by cortical neuron cultures, and its activation-triggered Ca(2+) entry and mitochondrial dysfunction played important roles in the ATP-induced neuronal death.
authors: Department of Environmental Biochemistry, Kyoto Pharmaceutical University, Kyoto, Japan.
authors: Kentaro
authors: K
authors: Nishida
authors: Tsunetoshi
authors: T
authors: Nakatani
authors: Akihiro
authors: A
authors: Ohishi
authors: Hiroto
authors: H
authors: Okuda
authors: Youichirou
authors: Y
authors: Higashi
authors: Takaaki
authors: T
authors: Matsuo
authors: Sadaki
authors: S
authors: Fujimoto
authors: Kazuki
authors: K
authors: Nagasawa
mesh_terms: D000255:Adenosine Triphosphate / Q000633:toxicity; D000818:Animals; D020013:Calcium Signaling / Q000502:physiology; D016923:Cell Death / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism* / Q000473:pathology*; D028361:Mitochondrial Diseases / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D009474:Neurons / Q000378:metabolism* / Q000473:pathology*; D061251:Primary Cell Culture; D051381:Rats; D058486:Receptors, Purinergic P2X7 / Q000378:metabolism* / Q000502:physiology
chemical_list: D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate