title: Autophagy Mediates Astrocyte Death During Zinc-Potentiated Ischemia--Reperfusion Injury.
abstract: Pathological release of excess zinc ions and the resultant increase in intracellular zinc has been implicated in ischemic brain cell death, although the underlying mechanisms are not fully understood. Since zinc promotes the formation of the autophagic signal, reactive oxygen species (ROS), and increases autophagy, a known mechanism of cell death, we hypothesized that autophagy is involved in zinc-induced hypoxic cell death. To study this hypothesis, we determined the effect of zinc on autophagy and ROS generation in C8-D1A astrocytes subjected to hypoxia and rexoygenation (H/R), simulating ischemic stroke. C8-D1A astrocytes subjected to 3-h hypoxia and 18-h reoxygenation exhibited dramatically increased autophagy and astrocyte cell death in the presence of 100 μM zinc. Pharmacological inhibition of autophagy decreased zinc-potentiated H/R-induced cell death, while scavenging ROS reduced both autophagy and cell death caused by zinc-potentiated H/R. These data indicate that zinc-potentiated increases in ROS lead to over-exuberant autophagy and increased cell death in H/R-treated astrocytes. Furthermore, our elucidation of this novel mechanism indicates that modulation of autophagy, ROS, and zinc levels may be useful targets in decreasing brain damage during stroke.
authors.affiliation: Department of Pharmaceutical Sciences, University of New Mexico Health Sciences Center, Albuquerque, NM, 87131, USA.
authors.forename: Rong
authors.initials: R
authors.lastname: Pan
authors.forename: Graham S
authors.initials: GS
authors.lastname: Timmins
authors.forename: Wenlan
authors.initials: W
authors.lastname: Liu
authors.forename: Ke Jian
authors.initials: KJ
authors.lastname: Liu
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000473:pathology; D001343:Autophagy / Q000187:drug effects*; D015153:Blotting, Western; D018929:Cell Culture Techniques; D015687:Cell Hypoxia / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002712:Chlorides / Q000494:pharmacology; D051379:Mice; D017382:Reactive Oxygen Species / Q000378:metabolism; D015427:Reperfusion Injury / Q000378:metabolism* / Q000473:pathology; D020521:Stroke / Q000378:metabolism* / Q000473:pathology; D015032:Zinc / Q000378:metabolism*; D017967:Zinc Compounds / Q000494:pharmacology
chemical_list: D002712:Chlorides; D017382:Reactive Oxygen Species; D017967:Zinc Compounds; C016837:zinc chloride; D015032:Zinc