Ca v 1.2 L-type Ca2+ channel protects mast cells against activation-induced cell death by preventing mitochondrial integrity disruption

Mol Immunol. 2009 Jul;46(11-12):2370-80. doi: 10.1016/j.molimm.2009.03.017. Epub 2009 May 17.

Abstract

In non-excitable cells, store-operated Ca(2+) channels (SOCs) are the principal routes of Ca(2+) entry. Recently, store-independent Ca(2+) channels which are pharmacologically and/or immunologically similar to L-type Ca(2+) channels (LTCCs) have been shown to exist in various hematopoietic cells, including T cells, B cells and neutrophils. We previously reported that mast cells express LTCCs which regulate mast cell effector responses in a distinct manner from SOCs. In the present study, we examined the possible role for LTCCs in mast cell survival. Both RBL-2H3 mast cells and bone marrow-derived mast cells underwent considerable apoptosis after treatment with thapsigargin (Tg) but not stimulation through the high-affinity IgE receptor (Fc epsilon RI). The LTCC-selective antagonists such as nifedipine greatly augmented Fc epsilon RI-mediated apoptosis, while the LTCC-selective agonist (S)-BayK8644 blocked Tg-induced apoptosis. The modulation of apoptosis was accompanied by altered mitochondrial integrity, as measured with the mitochondrial membrane potential, cytochrome c release and caspase-3/7 activation. Fc epsilon RI stimulation induced mitochondrial Ca(2+) ([Ca(2+)](m)) entry through both SOCs and LTCCs, while Tg evoked [Ca(2+)](m) entry through LTCCs but not SOCs. The LTCC-selective antagonists blocked [Ca(2+)](m) entry, whereas (S)-BayK8644 augmented Tg-induced [Ca(2+)](m) entry. Moreover, blockade of the expression of the alpha(1C) subunit of Ca(v)1.2 LTCC using small-interfering RNA strongly augmented Fc epsilon RI-mediated apoptosis, mitochondrial integrity, and mitochondrial Ca(2+) collapse, and abolished the protective effects of (S)-BayK8644 against Tg-induced apoptosis. These findings suggest that Ca(v)1.2 LTCC protects mast cells against activation-induced cell death by preventing mitochondrial integrity disruption.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / pharmacology
  • Animals
  • Apoptosis*
  • Bone Marrow Cells / drug effects
  • Bone Marrow Cells / physiology
  • Calcium Channels, L-Type / physiology*
  • Calcium Signaling
  • Cell Line
  • Cell Survival
  • Ion Channel Gating
  • Mast Cells / drug effects
  • Mast Cells / physiology*
  • Membrane Potential, Mitochondrial
  • Mice
  • Mitochondria / drug effects
  • Mitochondria / physiology*
  • Nifedipine / pharmacology
  • Protein Subunits / drug effects
  • Protein Subunits / physiology
  • Receptors, IgE / metabolism
  • Thapsigargin / pharmacology

Substances

  • CACNA1C protein, mouse
  • Calcium Channels, L-Type
  • Fc-epsilon receptor I beta-chain, mouse
  • Protein Subunits
  • Receptors, IgE
  • Thapsigargin
  • 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
  • Nifedipine