Genetic ablation of calcium-independent phospholipase A2γ (iPLA2γ) attenuates calcium-induced opening of the mitochondrial permeability transition pore and resultant cytochrome c release

Sung Ho Moon, Christopher M. Jenkins, Michael A. Kiebish, Harold F. Sims, David J. Mancuso, Richard W. Gross

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Herein, we demonstrate that calcium-independent phospholipase A 2γ (iPLA2γ) is a critical mechanistic participant in the calcium-induced opening of the mitochondrial permeability transition pore (mPTP). Liver mitochondria from iPLA2γ -/-mice were markedly resistant to calcium-induced swelling in the presence or absence of phosphate in comparison with wild-type littermates. Furthermore, the iPLA2γ enantioselective inhibitor (R)-(E)-6-(bromomethylene)-3-(1-naphthalenyl)-2H-tetrahydropyran-2-one ((R)-BEL) was markedly more potent than (S)-BEL in inhibiting mPTP opening in mitochondria from wildtype liver in comparison with hepatic mitochondria from iPLA2γ-/- mice. Intriguingly, low micromolar concentrations of long chain fatty acyl-CoAs and the non-hydrolyzable thioether analog of palmitoyl-CoA markedly accelerated Ca2+-induced mPTP opening in liver mitochondria from wild-type mice. The addition of L-carnitine enabled the metabolic channeling of acyl-CoA through carnitine palmitoyltransferases (CPT-1/2) and attenuated the palmitoyl-CoA-mediated amplification of calcium-induced mPTP opening. In contrast, mitochondria from iPLA2γ-/- mice were insensitive to fatty acyl- CoA-mediated augmentation of calcium-induced mPTP opening. Moreover, mitochondria from iPLA2γ-/- mouse liver were resistant to Ca2+/t-butyl hydroperoxide-induced mPTP opening in comparison with wild-type littermates. In support of these findings, cytochrome c release from iPLA2γ-/- mitochondria was dramatically decreased in response to calcium in the presence or absence of either t-butyl hydroperoxide or phenylarsine oxide in comparison with wild-type littermates. Collectively, these results identify iPLA2γ as an important mechanistic component of the mPTP, define its downstream products as potent regulators of mPTP opening, and demonstrate the integrated roles of mitochondrial bioenergetics and lipidomic flux in modulating mPTP opening promoting the activation of necrotic and necroapoptotic pathways of cell death.

Original languageEnglish
Pages (from-to)29837-29850
Number of pages14
JournalJournal of Biological Chemistry
Volume287
Issue number35
DOIs
StatePublished - Aug 24 2012

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