Passive regeneration of glutathione: Glutathione reductase regulation from the freeze-tolerant North American wood frog, Rana sylvatica

We examined the regulation of glutathione reductase, the enzyme involved in recycling glutathione, in both the frozen and unfrozen state

Neal J. Dawson


Scholarcy highlights

  • The North American wood frog, Rana sylvatica, is able to overwinter in a remarkable fashion; it freezes solid where up to 70% of its total body water is converted into extracellular ice
  • This study of the regulation of Glutathione reductase in the freeze-tolerant frog R. sylvatica provides useful insights into the maintenance of the cellular redox states as well as the GSSG/GSH ratios involved in apoptotic cell signaling
  • GR from R. sylvatica seems to have coupled an increase in the affinity for GSSG with a natural increase in the concentration of glucose during freezing
  • Cytosolic concentrations of GSH are significantly higher in R. sylvatica than in other closely related frog species, an increase in GR activity may be vital to maintaining GSH/GSSG levels, in the mitochondria
  • The mitochondrial production of reactive oxygen species has been linked to apoptotic signaling, and GR activity may be augmented in order to combat the mitochondrial production of ROS during thawinduced reperfusion
  • Glutathione reductase activity from both the control and frozen state showed dramatic reduction in substrate specificity for oxidized glutathione when measured in the presence of glucose and a increase when measured in the presence of levels of urea encountered in the frozen state
  • It is clear from this study and others that the role of GSH and GR maintenance of the mitochondrial redox environment during freezing in R. sylvatica should be explored in greater detail, as it could provide valuable insight into disease pathology by offering an alternative perspective on the role of GR during ischemia

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