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Intracellular calcium release is required for caspase-3 and -9 activation

Lee Tantral1, Krishnamurthy Malathi, Shinya Kohyama

  • 1Vascular Biology Laboratory, Department of Medicine, St. Luke's Roosevelt Hospital Center, New York, NY 10025, USA.

Cell Biochemistry and Function
|December 26, 2003
PubMed

Insights

Inositol trisphosphate receptors (IP3Rs) mediate calcium (Ca2+) release crucial for T-cell receptor-induced apoptosis. IP3R-deficient cells resist apoptosis by not activating caspases-3 and -9, independent of Bcl-2.

Area of Science:

  • Cellular biology
  • Immunology
  • Molecular biology

Background:

  • Intracellular calcium ([Ca2+]i) regulates vital cellular processes, including apoptosis.
  • The precise proteins linking [Ca2+]i signaling to apoptosis remain incompletely elucidated.
  • Previous work demonstrated T-cell receptor (TCR)-induced apoptosis resistance in inositol trisphosphate receptor (IP3R)-deficient cells due to impaired Ca2+ release and calcineurin activation.

Purpose of the Study:

  • To investigate the role of IP3R-mediated calcium release in the activation of apoptosis-related caspases.
  • To determine if Bcl-2 expression is a determining factor in the observed apoptosis resistance in IP3R-deficient cells.

Main Methods:

  • Utilized IP3R-deficient cells and control cells.
  • Stimulated cells via T-cell receptor (TCR) signaling.
  • Assessed caspase-9 and caspase-3 activation.
  • Quantified Bcl-2 protein expression levels.

Main Results:

  • IP3R-deficient cells exhibited resistance to TCR-induced apoptosis.
  • Caspase-9 and caspase-3 activation were significantly reduced in IP3R-deficient cells post-TCR stimulation.
  • Bcl-2 expression levels were comparable between IP3R-deficient and control cells.

Conclusions:

  • IP3R-mediated calcium release is critical for the activation of caspase-9 and caspase-3 during TCR-induced apoptosis.
  • This calcium signaling pathway regulates caspase activity independently of Bcl-2 expression.
  • IP3Rs represent a key link between calcium homeostasis and the apoptotic machinery in T-cells.

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