Increased nuclear thioredoxin-1 potentiates cadmium-induced cytotoxicity

Toxicol Sci. 2013 Jan;131(1):84-94. doi: 10.1093/toxsci/kfs271. Epub 2012 Sep 7.

Abstract

Cadmium (Cd) is a widely dispersed environmental agent that causes oxidative toxicity through mechanisms that are sensitive to thioredoxin-1 (Trx1). Trx1 is a cytoplasmic protein that translocates to nuclei during oxidative stress. Recent research shows that interaction of Trx1 with actin plays a critical role in cell survival and that increased nuclear Trx-1 potentiates proinflammatory signaling and death in cell and mouse models. These observations indicate that oxidative toxicity caused by low-dose Cd could involve disruption of actin-Trx1 interaction, nuclear Trx1 translocation, and potentiation of proinflammatory cell death mechanisms. In this study, we investigated the role of nuclei-localized Trx1 in Cd-induced inflammation and cytotoxicity using in vitro and in vivo models. The results show that Cd stimulated nuclear translocation of Trx1 and p65 of NF-κB. Elevation of Trx1 in nuclei in in vitro cells and kidney of transgenic mice potentiated Cd-stimulated NF-κB activation and cell death. Cd-stimulated Trx1 nuclear translocation and NF-κB activation were inhibited by cytochalasin D, an inhibitor of actin polymerization, suggesting that actin regulates Trx1 nuclear translocation and NF-κB activation by Cd. A nuclear-targeted dominant negative form of Trx1 blocked Cd-stimulated NF-κB activation and decreased cell death. Addition of zinc, known to antagonize Cd toxicity by increasing metallothionein, had no effect on Cd-stimulated nuclear translocation of Trx1 and NF-κB activation. Taken together, the results show that nuclear translocation and accumulation of redox-active Trx1 in nuclei play an important role in Cd-induced inflammation and cell death.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Blotting, Western
  • Cadmium / toxicity*
  • Cell Culture Techniques
  • Cell Nucleus / drug effects*
  • Cell Nucleus / metabolism
  • Cell Survival / drug effects
  • Cysteine / metabolism
  • Dose-Response Relationship, Drug
  • Electrophoretic Mobility Shift Assay
  • Environmental Pollutants / toxicity*
  • Gene Expression / drug effects
  • Glutathione / metabolism
  • HeLa Cells
  • Humans
  • Immunohistochemistry
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Microscopy, Fluorescence
  • NF-kappa B / metabolism
  • Nuclear Localization Signals / genetics
  • Oxidation-Reduction
  • Protein Transport
  • Thioredoxins / genetics
  • Thioredoxins / metabolism*

Substances

  • Environmental Pollutants
  • NF-kappa B
  • Nuclear Localization Signals
  • TXN protein, human
  • Cadmium
  • Thioredoxins
  • Glutathione
  • Cysteine