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Chondrocyte apoptosis induced by hydrogen peroxide requires caspase activation but not mitochondrial pore transition

Marvin Y Lo1, Hubert T Kim

  • 1Department of Orthopaedic Surgery, University of California, San Francisco, CA, USA.

Journal of Orthopaedic Research : Official Publication of the Orthopaedic Research Society
|August 12, 2004
PubMed

Insights

Hydrogen peroxide (H2O2) induces chondrocyte apoptosis via caspase activation. Inhibiting mitochondrial permeability transition did not prevent this cell death, indicating caspases are the key mediators.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Background:

  • Chondrocyte apoptosis contributes to cartilage degradation in joint diseases.
  • Hydrogen peroxide (H2O2) is implicated in oxidative stress-induced chondrocyte death.

Purpose of the Study:

  • To investigate whether inhibiting mitochondrial permeability transition or caspase enzymes can prevent H2O2-induced chondrocyte apoptosis.
  • To elucidate the specific molecular pathways involved in H2O2-induced chondrocyte cell death.

Main Methods:

  • Primary human chondrocytes were isolated and exposed to H2O2 to induce apoptosis.
  • Apoptosis was quantified using ELISA for nucleosome formation and TUNEL analysis.
  • Chondrocytes were pre-treated with inhibitors of mitochondrial permeability transition or various caspase inhibitors before H2O2 exposure.

Main Results:

  • H2O2 induced chondrocyte apoptosis in a time- and dose-dependent manner.
  • Inhibitors of mitochondrial permeability transition failed to block H2O2-induced apoptosis.
  • Non-selective, caspase 3-selective, and caspase 1-selective inhibitors all effectively blocked H2O2-induced chondrocyte apoptosis.

Conclusions:

  • H2O2 triggers chondrocyte apoptosis primarily through caspase activation.
  • Mitochondrial membrane permeability transition is not the critical pathway for H2O2-induced chondrocyte apoptosis.
  • Targeting caspases may represent a therapeutic strategy for preventing cartilage damage in oxidative stress-related conditions.

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