Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Impairment of lung aconitase activity, citric acid cycle, and mitochondrial respiration by hyperoxia necessitates the elevation of glycolysis for energy production and of pentose shunt activity for reducing equivalents. The molecular mechanisms that allow increased glucose utilization are unknown. Adult male and female rats were adapted to sublethal hyperoxia, equivalent to 83% oxygen at sea level, or air for 7 days. Lung RNA and protein increased in hyperoxia (197 and 57%, respectively), whereas total DNA was unchanged. In hyperoxia, lung total hexokinase (HK) activity increased threefold, and mRNAs for HK-II and -III were specifically upregulated. HK-I mRNA was unchanged. mRNAs for HK-II and -III gradually increased during the first 72 h in hyperoxia. HK-II mRNA was significantly elevated at 72 h, preceding changes in lung cell populations. Although virtually absent in air, HK-II activity was highly expressed in hyperoxia. Among lung glucose transporters, specific expression of mRNAs for GLUT-4 (insulin dependent) and sodium-glucose cotransporter-1 was decreased, whereas that for GLUT-1 was minimally changed. Adaptation to hyperoxia involves coordinated changes in gene expression for the proteins regulating pulmonary glucose transport.
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PMID:Changes in pulmonary expression of hexokinase and glucose transporter mRNAs in rats adapted to hyperoxia. 953 Jan 66

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.
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PMID:Elevated expression of hexokinase II protects human lung epithelial-like A549 cells against oxidative injury. 1216 77

This study examined the effects of different oxygenation levels and substrate availability on cardiac performance, metabolism, and biochemistry in sexually immature male and female rainbow trout (Oncorhynchus mykiss). Ventricle strips were electrically paced (0.5 Hz, 14 degrees C) in hyperoxic or hypoxic Ringer solution. Our results demonstrate that 1) males sustain isometric force production (F) longer than females under hyperoxia (P O2 = 640 mmHg) with exogenous glucose present; 2) contractility is not maintained under moderate (P O2 = 130 mmHg) or severe hypoxia (P O2 = 10-20 mmHg) with glucose in either sex; however, following reoxygenation, F is higher in females compared with males; and 3) female tissue has higher lactate levels, net lactate efflux, and lactate dehydrogenase activity than males, whereas males have higher glycogen, citrate synthase, and beta-hydroxy acyl-CoA dehydrogenase activities, and greater inotropic responses to exogenous glucose and octanoate. No sex differences were detected in responsiveness to epinephrine and inhibitors of glucose transport or activities of hexokinase and pyruvate kinase. We conclude that sex differences exist in rainbow trout cardiac tissue: females appear to prefer glycolysis for ATP production, whereas males have a higher capacity for aerobic and lipid metabolism.
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PMID:Sex differences in energy metabolism and performance of teleost cardiac tissue. 1703 42

Due to the substantial photosynthetic biomass in their habitat, salmonids such as the rainbow trout (Oncorhynchus mykiss) can be subject to hyperoxia in addition to high temperatures associated with climate change. Both stressful conditions increase the incidence of damaging reactive oxygen species (ROS). The mitochondrial association of hexokinase has been shown to increase in the hearts of certain fish experiencing hypoxia in a putative cardioprotective response to oxidative stress. In this study, the mitochondrial association of hexokinase I (HKI) and markers of oxidative damage and metabolic stress were probed to elucidate the cardioprotective role of hexokinase in the rainbow trout. Results showed that the co-administration of hyperoxia and hyperthermia increased the ventricular mitochondrially-bound fraction of HKI, whereas exposure to hyperthermia in normoxia had no effect; in the combined condition there was little evidence of increased stress. A second in vitro study using ventricular strips and isolated cardiomyocytes was undertaken to reconcile the cardioprotective role of HK in the rainbow trout with findings in mammalian studies, confirming that mitochondrial association of HK maintains aerobic efficiency and inhibits apoptosis. Finally, protein sequence analysis suggested that the physiological contributions of HKI and HKII in salmonids vary from those in mammals, further explaining the dynamic nature of the traditionally-inert HKI. Together, these findings help to explain the broader functions of HKI in the salmonid heart, and illustrate the role of complex environmental conditions in defining physiological responses.
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PMID:Cardioprotective mitochondrial binding by hexokinase I is induced by a hyperoxic acute thermal insult in the rainbow trout (Oncorhynchus mykiss). 2872 90