A Glutathione-Nrf2-Thioredoxin Cross-Talk Ensures Keratinocyte Survival and Efficient Wound Repair

PLoS Genet. 2016 Jan 25;12(1):e1005800. doi: 10.1371/journal.pgen.1005800. eCollection 2016 Jan.

Abstract

The tripeptide glutathione is the most abundant cellular antioxidant with high medical relevance, and it is also required as a co-factor for various enzymes involved in the detoxification of reactive oxygen species and toxic compounds. However, its cell-type specific functions and its interaction with other cytoprotective molecules are largely unknown. Using a combination of mouse genetics, functional cell biology and pharmacology, we unraveled the function of glutathione in keratinocytes and its cross-talk with other antioxidant defense systems. Mice with keratinocyte-specific deficiency in glutamate cysteine ligase, which catalyzes the rate-limiting step in glutathione biosynthesis, showed a strong reduction in keratinocyte viability in vitro and in the skin in vivo. The cells died predominantly by apoptosis, but also showed features of ferroptosis and necroptosis. The increased cell death was associated with increased levels of reactive oxygen and nitrogen species, which caused DNA and mitochondrial damage. However, epidermal architecture, and even healing of excisional skin wounds were only mildly affected in the mutant mice. The cytoprotective transcription factor Nrf2 was strongly activated in glutathione-deficient keratinocytes, but additional loss of Nrf2 did not aggravate the phenotype, demonstrating that the cytoprotective effect of Nrf2 is glutathione dependent. However, we show that deficiency in glutathione biosynthesis is efficiently compensated in keratinocytes by the cysteine/cystine and thioredoxin systems. Therefore, our study highlights a remarkable antioxidant capacity of the epidermis that ensures skin integrity and efficient wound healing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antioxidants / metabolism
  • Apoptosis / genetics
  • Cell Survival
  • DNA Damage / genetics
  • Glutamate-Cysteine Ligase / deficiency
  • Glutamate-Cysteine Ligase / genetics
  • Glutamate-Cysteine Ligase / metabolism
  • Glutathione / biosynthesis
  • Glutathione / metabolism*
  • Keratinocytes / metabolism
  • Keratinocytes / pathology
  • Mice
  • NF-E2-Related Factor 2 / genetics
  • NF-E2-Related Factor 2 / metabolism*
  • Oxidative Stress
  • Reactive Oxygen Species / metabolism
  • Skin / metabolism*
  • Skin / pathology
  • Thioredoxins / genetics*
  • Thioredoxins / metabolism
  • Wound Healing / genetics

Substances

  • Antioxidants
  • NF-E2-Related Factor 2
  • Nfe2l2 protein, mouse
  • Reactive Oxygen Species
  • Thioredoxins
  • Glutamate-Cysteine Ligase
  • Glutathione

Grant support

This work was supported by the Swiss National Science Foundation 310030_132884, www.snf.ch, Promedica Stiftung Chur, and by the CERIES Award. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.