title: Ca v 1.2 L-type Ca2+ channel protects mast cells against activation-induced cell death by preventing mitochondrial integrity disruption.
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.
authors.affiliation: Division of Molecular Cell Immunology and Allergology, Nihon University Graduate School of Medical Science, Tokyo, Japan. ysuzuki@med.nihon-u.ac.jp
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Yoshimaru
authors.forename: Toshio
authors.initials: T
authors.lastname: Inoue
authors.forename: Chisei
authors.initials: C
authors.lastname: Ra
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D001854:Bone Marrow Cells / Q000187:drug effects / Q000502:physiology; D020746:Calcium Channels, L-Type / Q000502:physiology*; D020013:Calcium Signaling; D002460:Cell Line; D002470:Cell Survival; D015640:Ion Channel Gating; D008407:Mast Cells / Q000187:drug effects / Q000502:physiology*; D053078:Membrane Potential, Mitochondrial; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D021122:Protein Subunits / Q000187:drug effects / Q000502:physiology; D017455:Receptors, IgE / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: C514350:CACNA1C protein, mouse; D020746:Calcium Channels, L-Type; C521907:Fc-epsilon receptor I beta-chain, mouse; D021122:Protein Subunits; D017455:Receptors, IgE; D019284:Thapsigargin; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009543:Nifedipine