title: P2X7 receptor activation regulates microglial cell death during oxygen-glucose deprivation.
abstract: Brain-resident microglia may promote tissue repair following stroke but, like other cells, they are vulnerable to ischemia. Here we identify mechanisms involved in microglial ischemic vulnerability. Using time-lapse imaging of cultured BV2 microglia, we show that simulated ischemia (oxygen-glucose deprivation; OGD) induces BV2 microglial cell death. Removal of extracellular Ca(2+) or application of Brilliant Blue G (BBG), a potent P2X7 receptor (P2X7R) antagonist, protected BV2 microglia from death. To validate and extend these in vitro findings, we assessed parenchymal microglia in freshly isolated hippocampal tissue slices from GFP-reporter mice (CX3CR1(GFP/+)). We confirmed that calcium removal or application of apyrase, an ATP-degrading enzyme, abolished OGD-induced microglial cell death in situ, consistent with involvement of ionotropic purinergic receptors. Indeed, whole cell recordings identified P2X7R-like currents in tissue microglia, and OGD-induced microglial cell death was inhibited by BBG. These pharmacological results were complemented by studies in tissue slices from P2X7R null mice, in which OGD-induced microglia cell death was reduced by nearly half. Together, these results indicate that stroke-like conditions induce calcium-dependent microglial cell death that is mediated in part by P2X7R. This is the first identification of a purinergic receptor regulating microglial survival in living brain tissues. From a therapeutic standpoint, these findings could help direct novel approaches to enhance microglial survival and function following stroke and other neuropathological conditions.
authors.affiliation: Department of Biology, University of Iowa, 369 Biology Building, Iowa City, IA 52242, USA.
authors.forename: Ukpong B
authors.initials: UB
authors.lastname: Eyo
authors.forename: Sam A
authors.initials: SA
authors.lastname: Miner
authors.forename: Katelin E
authors.initials: KE
authors.lastname: Ahlers
authors.forename: Long-Jun
authors.initials: LJ
authors.lastname: Wu
authors.forename: Michael E
authors.initials: ME
authors.lastname: Dailey
mesh_terms: D000818:Animals; D001081:Apyrase / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000172:deficiency*; D006624:Hippocampus / Q000187:drug effects / Q000503:physiopathology; D000860:Hypoxia / Q000378:metabolism*; D007511:Ischemia / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D017628:Microglia / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology; D058486:Receptors, Purinergic P2X7 / Q000235:genetics / Q000502:physiology*; D012394:Rosaniline Dyes / Q000494:pharmacology
chemical_list: D058920:Purinergic P2X Receptor Antagonists; D058486:Receptors, Purinergic P2X7; D012394:Rosaniline Dyes; D001081:Apyrase; D005947:Glucose; C004692:coomassie Brilliant Blue; D002118:Calcium
keywords: ATP; Cell death; Microglia; OGD; P2X7; Stroke