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Overexpression of cytosolic group IVA phospholipase A2 protects cells from Ca2+-dependent death

Javier Casas1, Miguel A Gijón, Ana G Vigo

  • 1Institute of Molecular Biology and Genetics, Spanish Research Council and University of Valladolid School of Medicine, 47003 Valladolid, Spain.

The Journal of Biological Chemistry
|January 13, 2006
PubMed

Insights

High levels of arachidonic acid prevent early cell death caused by calcium overload in human embryonic kidney cells. Expressing enhanced green fluorescent protein-conjugated cytosolic Group IVA phospholipase A2 alpha (EGFP-cPLA2α) also protects cells.

Area of Science:

  • Cell Biology
  • Biochemistry
  • Toxicology

Background:

  • Calcium ionophores like ionomycin trigger rapid apoptosis-like events in human embryonic kidney cells.
  • These early events include plasma membrane blebbing, mitochondrial depolarization, and phosphatidylserine externalization, but not caspase activation or chromatin condensation.

Purpose of the Study:

  • To investigate the role of cytosolic Group IVA phospholipase A2 alpha (cPLA2α) in ionomycin-induced cell death.
  • To determine if arachidonic acid can prevent calcium overload-induced cell death.

Main Methods:

  • Utilized human embryonic kidney cells expressing enhanced green fluorescent protein-conjugated cPLA2α (EGFP-cPLA2α) or a calcium-binding mutant (EGFP-D43N-cPLA2α).
  • Assessed ionomycin-induced apoptosis-like events, including phosphatidylserine externalization and mitochondrial depolarization.
  • Investigated the protective effects of exogenous arachidonic acid.

Main Results:

  • EGFP-cPLA2α expression prevented ionomycin-induced phosphatidylserine externalization and cell death.
  • Cells expressing the calcium-binding mutant EGFP-D43N-cPLA2α remained susceptible to ionomycin.
  • Pretreatment with arachidonic acid protected both non-expressing and EGFP-D43N-cPLA2α-expressing cells from ionomycin.
  • EGFP-cPLA2α-expressing cells showed reduced mitochondrial depolarization during calcium overload.

Conclusions:

  • Early cell death induced by calcium overload can be mitigated by high levels of arachidonic acid.
  • cPLA2α plays a protective role against calcium-induced cell death, potentially through mechanisms involving arachidonic acid metabolism.

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