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Increased oxidative stress and antioxidant expression in mouse keratinocytes following exposure to paraquat

Journal Article · · Toxicology and Applied Pharmacology
;  [1];  [2];  [1];  [3]
  1. Department of Pharmacology and Toxicology, Rutgers University (United States)
  2. Department of Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, NJ 08854 (United States)
  3. Department of Environmental and Occupational Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, NJ 08854 (United States)
Paraquat (1,1'-dimethyl-4,4'-bipyridinium) is a widely used herbicide known to induce skin toxicity. This is thought to be due to oxidative stress resulting from the generation of cytotoxic reactive oxygen intermediates (ROI) during paraquat redox cycling. The skin contains a diverse array of antioxidant enzymes which protect against oxidative stress including superoxide dismutase (SOD), catalase, glutathione peroxidase-1 (GPx-1), heme oxygenase-1 (HO-1), metallothionein-2 (MT-2), and glutathione-S-transferases (GST). In the present studies we compared paraquat redox cycling in primary cultures of undifferentiated and differentiated mouse keratinocytes and determined if this was associated with oxidative stress and altered expression of antioxidant enzymes. We found that paraquat readily undergoes redox cycling in both undifferentiated and differentiated keratinocytes, generating superoxide anion and hydrogen peroxide as well as increased protein oxidation which was greater in differentiated cells. Paraquat treatment also resulted in increased expression of HO-1, Cu,Zn-SOD, catalase, GSTP1, GSTA3 and GSTA4. However, no major differences in expression of these enzymes were evident between undifferentiated and differentiated cells. In contrast, expression of GSTA1-2 was significantly greater in differentiated relative to undifferentiated cells after paraquat treatment. No changes in expression of MT-2, Mn-SOD, GPx-1, GSTM1 or the microsomal GST's mGST1, mGST2 and mGST3, were observed in response to paraquat. These data demonstrate that paraquat induces oxidative stress in keratinocytes leading to increased expression of antioxidant genes. These intracellular proteins may be important in protecting the skin from paraquat-mediated cytotoxicity.
OSTI ID:
21140963
Journal Information:
Toxicology and Applied Pharmacology, Journal Name: Toxicology and Applied Pharmacology Journal Issue: 3 Vol. 231; ISSN TXAPA9; ISSN 0041-008X
Country of Publication:
United States
Language:
English

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