Elevated expression of hexokinase II protects human lung epithelial-like A549 cells against oxidative injury.
Increased glucose utilization and hexokinase (HK)-II expression are adaptive features of lung cells exposed to hypoxia or hyperoxia. HK-II is the most regulated isoform of HK. Whether its overexpression could be protective against oxidative stress was explored in human lung epithelial-like (A549) cells. HK-II was overexpressed in A549 cells in a tetracycline-repressible retroviral vector system. Elevated expression of HK-II was confirmed by Western blot and activity measurements. Cell death caused by exposure to hyperoxia was decreased in HK-II-overexpressing cells. This effect was reversed when HK-II expression was suppressed with doxycycline. A similar protective effect was observed in HK-II-overexpressing cells after treatment with 1 mM hydrogen peroxide for 48 h. At baseline, fluorescence microscopy showed that overexpressed HK-II was localized to mitochondria. Electron microscopic studies showed that hyperoxia-exposed HK-II overexpressors had better-preserved and quantitatively smaller mitochondria than those in which the HK-II expression was suppressed or in the nontransduced A549 cells. Mitochondrial membrane potential was increased in HK-II-overexpressing cells exposed to hyperoxia compared with the nontransduced control cells under similar conditions. The present study demonstrates that HK-II protects human lung epithelial-like A549 cells against oxidative insults by protecting the mitochondria.
Ahmad
Aftab
A
Department of Pediatrics, National Jewish Medical and Research Center, Denver, Colorado 80206, USA.
Ahmad
Shama
S
Schneider
B Kelly
BK
Allen
Corrie B
CB
Chang
Ling-Yi
LY
White
Carl W
CW
D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D019610:Cytoprotection; D005455:Fluorescent Antibody Technique; D005947:Glucose / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018496:Hyperoxia / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology; D008168:Lung / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000502:physiology; D016877:Oxidants / Q000494:pharmacology; D013194:Staining and Labeling
D016877:Oxidants; D006861:Hydrogen Peroxide; D006593:Hexokinase; D005947:Glucose