Role of rockfish (Sebastes schlegelii) glutaredoxin 1 in innate immunity, and alleviation of cellular oxidative stress: Insights into localization, molecular characteristics, transcription, and function

Glutaredoxin 1 from Evolutionary Ancient Hydra: Characteristics of the Enzyme and Its Possible Functions in Cell

Glutaredoxin (Grx) is an antioxidant redox protein that uses glutathione (GSH) as an electron donor. Grx plays a crucial role in various cellular processes, such as antioxidant defense, control of cellular redox state, redox control of transcription, reversible S-glutathionylation of specific proteins, apoptosis, cell differentiation, etc. In the current study, we have isolated and characterized dithiol glutaredoxin from Hydra vulgaris Ind-Pune (HvGrx1). Sequence analysis showed that HvGrx1 belongs to the Grx family with the classical Grx motif (CPYC). Phylogenetic analysis and homology modeling revealed that HvGrx1 is closely related to Grx2 from zebrafish. HvGrx1 gene was cloned and expressed in Escherichia coli cells; the purified protein had a molecular weight of 11.82 kDa. HvGrx1 efficiently reduced β-hydroxyethyl disulfide (HED) with the temperature optimum of 25°C and pH optimum 8.0. HvGrx1 was ubiquitously expressed in all body parts of Hydra. Expression of HvGrx1 mRNA and enzymatic activity of HvGrx1 were significantly upregulated post H2O2 treatment. When expressed in human cells, HvGrx1 protected the cells from oxidative stress and enhanced cell proliferation and migration. Although Hydra is a simple invertebrate, HvGrx1 is evolutionary closer to its homologs from higher vertebrates (similar to many other Hydra proteins).

Glutaredoxin 1 protects neurons from oxygen-glucose deprivation/reoxygenation (OGD/R)-induced apoptosis and oxidative stress via the modulation of GSK-3β/Nrf2 signaling

Increasing evidence has indicated that glutaredoxin 1 (GRX1) is a potent antioxidant protein that promotes cell survival under conditions of oxidative stress. Oxidative stress-induced neuronal injury contributes to cerebral ischemia/reperfusion injury. However, the role of GRX1-mediated antioxidant defense against neuronal damage during cerebral ischemia/reperfusion injury has not been thoroughly investigated. Thus, the objective of this study was to evaluate whether GRX1 protects neurons against oxygen-glucose deprivation/reoxygenation (OGD/R)-evoked oxidative stress injury in an in vitro model of cerebral ischemia/reperfusion injury. Our data revealed that GRX1 was induced by OGD/R treatment in neurons. Functional assays indicated that loss of GRX1 exacerbated OGD/R-induced apoptosis and the generation of reactive oxygen species (ROS), while GRX1 up-regulation protected against OGD/R-evoked neuronal injury. Further investigation revealed that GRX1 promoted the nuclear expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and enhanced transcription of the Nrf2/antioxidant response element (ARE) in GOD/R-exposed neurons. Furthermore, GRX1 promoted the activation of Nrf2/ARE associated with the modulation of glycogen synthase kinase-3β (GSK-3β). GSK-3β inhibition blocked GRX1 knockdown-mediated suppression of Nrf2 activation. Notably, the suppression of Nrf2 partially reversed GRX1-mediated anti-oxidative stress injury in OGD/R-exposed neurons. In summary, these findings indicate that GRX1 protects neurons against OGD/R-induced oxidative stress injury by enhancing Nrf2 activation via the modulation of GSK-3β. Our study suggests that GRX1 is a potential neuroprotective protein that protects against cerebral ischemia/reperfusion injury.