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Reactive oxygen species mediate the down-regulation of mitochondrial transcripts and proteins by tumour necrosis

José A Sánchez-Alcázar1, Erasmus Schneider, Inmaculada Hernández-Muñoz

  • 1Laboratorio Andaluz de Biología, Universidad Pablo de Olavide, Carretera de Utrera Km 1, Sevilla 41013, Spain. jasanalc@dex.upo.es

The Biochemical Journal
|December 10, 2002
PubMed

Insights

Tumor necrosis factor alpha (TNF-alpha) increases reactive oxygen species, decreasing mitochondrial gene expression and increasing glycolysis in L929 cells. Antioxidants block these effects, suggesting a direct link to TNF-alpha-induced cell death.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Tumor necrosis factor alpha (TNF-alpha) is a key cytokine involved in inflammation and immunity.
  • TNF-alpha can induce cellular responses, including cell death, through various signaling pathways.
  • Mitochondria play crucial roles in cellular energy production and apoptosis.

Purpose of the Study:

  • To investigate the effects of TNF-alpha-induced reactive oxygen species (ROS) on gene expression in L929 cells.
  • To determine the impact of TNF-alpha on mitochondrial and glycolytic pathways.
  • To elucidate the role of ROS in mediating TNF-alpha's cytotoxic effects.

Main Methods:

  • Treatment of L929 cells with TNF-alpha.
  • Measurement of steady-state mRNA levels for mitochondrial (ATPase 6-8) and nuclear-encoded glycolytic (GAPDH, phosphofructokinase) genes using quantitative PCR.
  • Assessment of protein levels for ATPase subunit a, cytochrome c oxidase subunit II, and phosphofructokinase using Western blotting.
  • Evaluation of the effects of ROS scavengers (butylated hydroxianisole, butylated hydroxytoluene) on gene expression, protein levels, and cell viability.

Main Results:

  • TNF-alpha treatment led to decreased mRNA levels of the mitochondrial transcript ATPase 6-8.
  • Concurrently, TNF-alpha increased mRNA levels of glycolytic enzymes GAPDH and phosphofructokinase.
  • Protein analysis revealed decreased levels of mitochondrial proteins (ATPase subunit a, cytochrome c oxidase subunit II) and increased levels of phosphofructokinase.
  • ROS scavengers prevented these changes in gene and protein expression and attenuated TNF-alpha-induced cytotoxicity.

Conclusions:

  • TNF-alpha-induced reactive oxygen species production directly impacts cellular metabolism.
  • These ROS mediate down-regulation of mitochondrial gene expression and up-regulation of glycolysis.
  • Antioxidant intervention can mitigate TNF-alpha's metabolic effects and cytotoxicity, highlighting a critical role for ROS in TNF-alpha signaling.

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