• Applied Biological Chemistry
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• v.48 no.1
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• pp.53-59
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• 2005

The effect of various stressors such as reductant ascorbic acid, signalling molecules (salicylic acid and methyl jasmonic acid), heavy metals $(NiCl_2,\;and\;MnSO_4)$ and NaCl on the glutathione peroxidase (GPX) activities and isoenzyme expression patterns were investigated in rice seedling roots. Total GPX activity increased according to the increase of ascorbic acid concentration. Prominent enhancement of GPX1 isozyme due to ascorbic acid contributed to the increase of total GPX activity. GPX showed different reactivity toward salicylic acid and methyl jasmonic acid. GPX activity increased at 0.1 mM salicylic acid, and then decreased thereafter. However, GPX increased gradually in a methyl jasmonic acid concentration-dependent manner, and 3 fold increase of GPX activity was found at 1 mM methyl jasmonic acid. Moreover, GPX1 isozyme increased according to the increase of salicylic acid, while GPX1 isozyme decreased according to the increase of methyl jasmonic acid. When metal ions were treated, GPX activity increased considerably according to the increase of $NiCl_2$ concentration, however, GPX activity increased about 2 fold at 0.5 mM $CuSO_4$ and then decreased. Enhancement of GPX1 isozyme contributed to the increase of total GPX activities in $NiCl_2-treated$ and $MnSO_4-treated$ rice seedlings. Total GPX activity increased 1.7 fold in response to 300 mM NaCl. Especially GPX2 isozyme showed gradual increase according to the increase of NaCl concentration.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.270-282
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• 2008

The yeast Saccharomyces cerevisiae has defense mechanisms identical to higher eukaryotes. It offers the potential for genome-wide experimental approaches owing to its smaller genome size and the availability of the complete sequence. It therefore represents an ideal eukaryotic model for studying cellular redox control and oxidative stress responses. S. cerevisiae Yap1 is a well-known transcription factor that is required for $H_2O_2$-dependent stress responses. Yap1 is involved in various signaling pathways in an oxidative stress response. The Gpx3 (Orp1/PHGpx3) protein is one of the factors related to these signaling pathways. It plays the role of a transducer that transfers the hydroperoxide signal to Yap1. In this study, using extensive proteomic and bioinformatics analyses, the function of the Gpx3 protein in an adaptive response against oxidative stress was investigated in wild-type, gpx3-deletion mutant, and gpx3-deletion mutant overexpressing Gpx3 protein strains. We identified 30 proteins that are related to the Gpx3-dependent oxidative stress responses and 17 proteins that are changed in a Gpx3-dependent manner regardless of oxidative stress. As expected, $H_2O_2$-responsive Gpx3-dependent proteins include a number of antioxidants related with cell rescue and defense. In addition, they contain a variety of proteins related to energy and carbohydrate metabolism, transcription, and protein fate. Based upon the experimental results, it is suggested that Gpx3-dependent stress adaptive response includes the regulation of genes related to the capacity to detoxify oxidants and repair oxidative stress-induced damages affected by Yap1 as well as metabolism and protein fate independent from Yap1.

• Biomolecules & Therapeutics
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• v.29 no.1
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• pp.52-57
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• 2021

Fumonisin B1 (FB1) structurally resembles sphingolipids and interferes with their metabolism leading to sphingolipid dysregulation. We questioned if FB1 could exacerbate liver or kidney toxicities in glutathione peroxidase 1 (Gpx1) and catalase (Cat) knockout mice. While higher serum levels of thiobarbituric acid reactive substances (TBARS) and sphinganine (Sa) were measured in Gpx1/Cat knockout mice (Gpx1/Cat KO) than wild type mice after 5 days of FB1 treatment, serum levels of alanine aminotransferase (ALT), sphingosine-1 phosphate (So-1-P), and sphinganine-1 phosphate (Sa-1-P) were found to be relatively low. Although Sa was highly elevated in Gpx1/Cat KO mice and wild mice, lower levels of So and Sa were found in both the kidney and liver tissues of Gpx/Cat KO mice than wild type mice after FB1 treatment. Paradoxically, FB1-induced cellular apoptosis and necrosis were hastened under oxidative stress in Gpx1/Cat KO mice.

• Preventive Nutrition and Food Science
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• v.8 no.1
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• pp.36-39
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• 2003

Many defined cell culture media were formulated over 3() years ago and may be deficient in certain micronutrients whose essentiality has only subsequently been recognised. The objective of this study was to evaluate whether alpha-minimal essential medium (MEM) supplemented with 10% foetal bovine serum contained sufficient selenium for optimal activity of the selenium containing enzymes cytosolic glutathione peroxidase (cGPx) and phospholipid hydroperoxide glutathione peroxidase (PHGPx) in cultured Chinese hamster ovary (CHO) cells. Additionally, the effect of zinc deficiency and metallothionein (MT) overexpression on cGPx and PHGPx activity was studied. The addition of 100 nM of selenous acid to the culture medium increased cGPx expression by 10-fold and PHGPx by about 2-fold in both wild-type CHO-K1 cells and CHO-K1 cells overexpressing mouse MT-1. Zinc deficiency had no significant effect on enzyme activity, but cells overexpressing mouse MT-1 had higher levels of cGPx activity. Zinc deficiency decreased cell survival but overexpression of MT-1 was partially protective, probably because its presence in quantity favoured the uptake, sequestration and cellular retention of any remaining zinc. This study demonstrates that selenium in complete alpha-MEM is insufficient for optimal cGPx and PHGPx activity and may compromise the cellular response to oxidative stress.

• BMB Reports
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• v.41 no.3
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• pp.204-209
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• 2008

The cDNAs encoding glutathione peroxidase (GPx) were cloned and sequenced from the liver of three Chinese carps with different tolerance to hepatotoxic microcystins, phyto-planktivorous silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis), and herbivorous grass carp (Ctenopharyngodon idellus). Using genome walker method, a 750 bp 5'-flanking region of the silver carp GPx gene was obtained, and several potential regulatory elements were identified in the promoter region of the GPx gene. The silver carp GPx gene was widely expressed in all tissues examined. Despite phylogenetic analysis, assigning this newly described carp GPx to the group of mammalian GPx2, the carp GPx seems more similar to GPx1 from a physiological point of view. The constitutive expression pattern of the three carp liver GPx gene, shows a positive relationship with their tolerance to microcystins.

• Journal of Plant Biotechnology
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• v.36 no.2
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• pp.149-156
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• 2009

Application of exogenous polyamines (PAs) reduced the paraquat (PQ)-induced cotyledon injuries in radish seedling plants with 1 mM spermidine (Spd) being the most effective protectant. PQ injury symptoms in the cotyledons, e.g., large accumulation of $H_2O_2$, and losses of fresh weight, chlorophyll, and proteins, were significantly alleviated. Likewise, analysis of $H_2O_2$-scavenging enzymes such as catalase (CAT) and guaiacol peroxidase (GPX) showed that pretreatment with Spd among PAs remarkably increased total CAT activity and strongly retarded PQ-induced rapid decline in total GPX activity. In a native gel assay, one CAT isozyme (CAT1) and two GPX isozymes (GPX1 and a newly synthesized GPX isozyme) proved to be more responsible for PQ tolerance, as manifested by the strong increases in their activities by Spd pretreatment. Based on these results, we can suggest that PAs (especially 1 mM Spd) may function as antioxidant protectors by invoking CAT and GPX enzymes which control the endogenous $H_2O_2$ level in radish cotyledons exposed to PQ.

• Journal of Ginseng Research
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• v.47 no.4
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• pp.561-571
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• 2023

Background: Escalating evidence shows that ginseng possesses an antiaging potential with cognitive enhancing activity. As mountain cultivated ginseng (MCG) is cultivated without agricultural chemicals, MCG has emerged as a popular herb medicine. However, little is known about the MCG-mediated pharmacological mechanism on brain aging. Methods: As we demonstrated that glutathione peroxidase (GPx) is important for enhancing memory function in the animal model of aging, we investigated the role of MCG as a GPx inducer using GPx-1 (a major type of GPx) knockout (KO) mice. We assessed whether MCG modulates redox and cholinergic parameters, and memory function in aged GPx-1 knockout KOmice. Results: Redox burden of aged GPx-1 KO mice was more evident than that of aged wild-type (WT) mice. Alteration of Nrf2 DNA binding activity appeared to be more evident than that of NFκB DNA binding activity in aged GPx-1 KO mice. Alteration in choline acetyltransferase (ChAT) activity was more evident than that in acetylcholine esterase activity. MCG significantly attenuated reductions in Nrf2 system and ChAT level. MCG significantly enhanced the co-localization of Nrf2-immunoreactivity and ChAT-immunoreactivity in the same cell population. Nrf2 inhibitor brusatol significantly counteracted MCG-mediated up-regulation in ChAT level and ChAT inhibition (by k252a) significantly reduced ERK phosphorylation by MCG, suggesting that MCG might require signal cascade of Nrf2/ChAT/ERK to enhance cognition. Conclusion: GPx-1 depletion might be a prerequisite for cognitive impairment in aged animals. MCG-mediated cognition enhancement might be associated with the activations of Nrf2, ChAT, and ERK signaling cascade.

• Journal of Veterinary Clinics
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• v.30 no.6
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• pp.409-414
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• 2013

In the present study, we investigated and compared the cardiopulmonary and oxidative stress effects of dogs undergoing open and thoracoscopic lung lobectomy. Ten healthy dogs, 5-8 years old, weighing 9-12 kg were used. The animals were randomly assigned to one of two groups according to the type of surgical procedure; open (group 1, n=5) or thoracoscopic lung lobectomy (group 2, n=5). Cardiopulmonary parameters, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) concentrations were measured. There were statistically significant changes in arterial blood gases values in both groups. Total anesthesia and surgical times were significantly shorter in thoracoscopic lobectomy group compared with open surgery group. Increases in plasma SOD and CAT levels, and decreases in GPx levels were observed in both groups after surgery. Significant difference in GPx levels was found when the groups were compared. The GPx level was significantly lower in the thoracoscopic lobectomy group compared with the open surgery group.

• Journal of Plant Biotechnology
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• v.34 no.3
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• pp.213-221
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• 2007

The treatment of radish cotyledons with a nitric oxide (NO)-releasing substance, sodium nitroprusside (SNP) resulted in an increased adventitious root development in a dose-dependent manner. However, this NO-mediated enhancement effect was reversed when either 0.5 mM EGTA (an extracellular $Ca^{2+}$ chelator) or 0.1 mM $LaCl_3$ (a calcium channel blocker) was applied with $50\;{\mu}M$ SNP. Our results also showed that guaiacol peroxidase (GPX) and syringaldazine peroxidase (SPX) activities, which are known to play a key role in rooting, were more largely increased during adventitious root induction in the cotyledons treated with SNP. However, the treatment of cotyledons with SNP plus $LaCl_3$ inhibited the SNP-induced increases in the activities of both GPX and SPX. Trifluoperazine (TFP), an antagonist of calmodulin (a specific calcium-binding protein), also delayed adventitious root formation and significantly reduced the root length and number of the SNP-treated cotyledons as well as the deactivation of GPX and SPX enzymes. In conclusion, our results suggest that calcium is involved in the NO response leading to induction of adventitious root through a regulation of GPX and SPX.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.258-264
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• 2011

Glutathione (GSH) has important roles in cellular defense against oxidative stress, 1) direct scavenging of reactive oxygen species (ROS), and 2) coenzyme of ROS scavenging enzyme like glutathione peroxidases (GPx). GSH peroxidase reduces free hydrogen peroxide to water using 2GSH. $N$-acetyl-L-cysteine (NAC), one of the antioxidants, is used as a precursor for intracellular GSH. In this study, relation of GSH, NAC, and GSH peroxidase was investigated through transcriptional expression of $GPX1$ and $GPX2$, which are GSH peroxidase encoding genes, in yeast cells treated with 0 mM to 20 mM of NAC or in combination with 100 Gy gamma-rays. The transcriptional expression of $GPX1$ and $GPX2$ was induced by NAC and 100 Gy gamma-rays. The gene expression of both GSH peroxidases was decreased with increasing concentrations of NAC in irradiated yeast cells. These results suggest that elevation of intracellular GSH by NAC and oxidative stress and ROS generated from gamma-rays induces expression of GSH peroxidase genes, and that NAC can protect the yeast cells against ROS generated from gamma-rays through direct scavenging of ROS and transcriptional activation of GSH peroxidase.