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• W2513244497 abstract "Calcium-independent phospholipase A2γ (iPLA2γ) is a mitochondrial enzyme that produces lipid second messengers that facilitate opening of the mitochondrial permeability transition pore (mPTP) and contribute to the production of oxidized fatty acids in myocardium. To specifically identify the roles of iPLA2γ in cardiac myocytes, we generated cardiac myocyte-specific iPLA2γ knock-out (CMiPLA2γKO) mice by removing the exon encoding the active site serine (Ser-477). Hearts of CMiPLA2γKO mice exhibited normal hemodynamic function, glycerophospholipid molecular species composition, and normal rates of mitochondrial respiration and ATP production. In contrast, CMiPLA2γKO mice demonstrated attenuated Ca2+-induced mPTP opening that could be rapidly restored by the addition of palmitate and substantially reduced production of oxidized polyunsaturated fatty acids (PUFAs). Furthermore, myocardial ischemia/reperfusion (I/R) in CMiPLA2γKO mice (30 min of ischemia followed by 30 min of reperfusion in vivo) dramatically decreased oxidized fatty acid production in the ischemic border zones. Moreover, CMiPLA2γKO mice subjected to 30 min of ischemia followed by 24 h of reperfusion in vivo developed substantially less cardiac necrosis in the area-at-risk in comparison with their WT littermates. Furthermore, we found that membrane depolarization in murine heart mitochondria was sensitized to Ca2+ by the presence of oxidized PUFAs. Because mitochondrial membrane depolarization and calcium are known to activate iPLA2γ, these results are consistent with salvage of myocardium after I/R by iPLA2γ loss of function through decreasing mPTP opening, diminishing production of proinflammatory oxidized fatty acids, and attenuating the deleterious effects of abrupt increases in calcium ion on membrane potential during reperfusion. Calcium-independent phospholipase A2γ (iPLA2γ) is a mitochondrial enzyme that produces lipid second messengers that facilitate opening of the mitochondrial permeability transition pore (mPTP) and contribute to the production of oxidized fatty acids in myocardium. To specifically identify the roles of iPLA2γ in cardiac myocytes, we generated cardiac myocyte-specific iPLA2γ knock-out (CMiPLA2γKO) mice by removing the exon encoding the active site serine (Ser-477). Hearts of CMiPLA2γKO mice exhibited normal hemodynamic function, glycerophospholipid molecular species composition, and normal rates of mitochondrial respiration and ATP production. In contrast, CMiPLA2γKO mice demonstrated attenuated Ca2+-induced mPTP opening that could be rapidly restored by the addition of palmitate and substantially reduced production of oxidized polyunsaturated fatty acids (PUFAs). Furthermore, myocardial ischemia/reperfusion (I/R) in CMiPLA2γKO mice (30 min of ischemia followed by 30 min of reperfusion in vivo) dramatically decreased oxidized fatty acid production in the ischemic border zones. Moreover, CMiPLA2γKO mice subjected to 30 min of ischemia followed by 24 h of reperfusion in vivo developed substantially less cardiac necrosis in the area-at-risk in comparison with their WT littermates. Furthermore, we found that membrane depolarization in murine heart mitochondria was sensitized to Ca2+ by the presence of oxidized PUFAs. Because mitochondrial membrane depolarization and calcium are known to activate iPLA2γ, these results are consistent with salvage of myocardium after I/R by iPLA2γ loss of function through decreasing mPTP opening, diminishing production of proinflammatory oxidized fatty acids, and attenuating the deleterious effects of abrupt increases in calcium ion on membrane potential during reperfusion. The salvage of jeopardized regions of myocardium during ischemia/reperfusion (I/R) 3The abbreviations used are: I/R,ischemia/reperfusion; CL,cardiolipin; CMiPLA2γKO,cardiac myocyte-specific iPLA2γ knock-out; EET,epoxyeicosatrienoic acid; FLP,flippase; HDoHE,hydroxydocosahexaenoic acid; HETE,hydroxyeicosatetraenoic acid; iPLA2γ,calcium-independent phospholipase A2γ; mPTP,mitochondrial permeability transition pore; oxoODE,oxo-octadecadienoic acid; PG,prostaglandin; I.S.,internal standard; oxlam,oxidized linoleic acid metabolite; FCCP,trifluoromethoxy carbonylcyanide phenylhydrazone; MRM,multiple reaction monitoring; AMPP,N-(4-aminomethylphenyl) pyridinium; TTC,triphenyltetrazolium chloride; D,diacyl; TPP+,tetraphenylphosphonium; LAD,left anterior descending; FRT,flippase recombinase target; MDMS-SL,multidimensional mass spectrometry-based shotgun lipidomics.; has been a long-standing goal of heart research. Because mortality and morbidity are related to infarct size, a variety of hemodynamic, metabolic, and pharmacological approaches have been used to reduce the severity of myocardial infarction during ischemia (1Bagai A. Dangas G.D. Stone G.W. Granger C.B. Reperfusion strategies in acute coronary syndromes.Circ. Res. 2014; 114: 1918-1928Crossref PubMed Scopus (70) Google Scholar, 2Sluijter J.P. Condorelli G. Davidson S.M. Engel F.B. Ferdinandy P. Hausenloy D.J. Lecour S. Madonna R. Ovize M. Ruiz-Meana M. Schulz R. Van Laake L.W. Nucleus of the European Society of Cardiology Working Group Cellular Biology of the Heart Novel therapeutic strategies for cardioprotection.Pharmacol. Ther. 2014; 144: 60-70Crossref PubMed Scopus (65) Google Scholar3Reddy K. Khaliq A. Henning R.J. Recent advances in the diagnosis and treatment of acute myocardial infarction.World J. Cardiol. 2015; 7: 243-276Crossref PubMed Google Scholar). Recent studies have accumulated evidence that the irreversible opening of the mitochondrial permeability transition pore (mPTP) upon oxidative stress is a principal mechanism of apoptotic/necrotic cardiac cell death accounting for the majority of I/R injury (4Hausenloy D.J. Yellon D.M. Myocardial ischemia-reperfusion injury: a neglected therapeutic target.J. Clin. Invest. 2013; 123: 92-100Crossref PubMed Scopus (1439) Google Scholar, 5Yellon D.M. Hausenloy D.J. Myocardial reperfusion injury.N. Engl. J. Med. 2007; 357: 1121-1135Crossref PubMed Scopus (2835) Google Scholar6Kwong J.Q. Molkentin J.D. Physiological and pathological roles of the mitochondrial permeability transition pore in the heart.Cell Metab. 2015; 21: 206-214Abstract Full Text Full Text PDF PubMed Scopus (279) Google Scholar). Although therapies for acute ischemia (e.g. reperfusion) have been extensively studied, at present there is no therapy for attenuating mPTP opening during reperfusion of ischemic zones in myocardium. Although the precise chemical composition of the mPTP is incompletely understood (6Kwong J.Q. Molkentin J.D. Physiological and pathological roles of the mitochondrial permeability transition pore in the heart.Cell Metab. 2015; 21: 206-214Abstract Full Text Full Text PDF PubMed Scopus (279) Google Scholar), a variety of initiators and modulators of mPTP opening has been identified (7Halestrap A.P. Clarke S.J. Javadov S.A. Mitochondrial permeability transition pore opening during myocardial reperfusion–a target for cardioprotection.Cardiovasc. Res. 2004; 61: 372-385Crossref PubMed Scopus (994) Google Scholar, 8Morciano G. Giorgi C. Bonora M. Punzetti S. Pavasini R. Wieckowski M.R. Campo G. Pinton P. Molecular identity of the mitochondrial permeability transition pore and its role in ischemia-reperfusion injury.J. Mol. Cell. Cardiol. 2015; 78: 142-153Abstract Full Text Full Text PDF PubMed Scopus (169) Google Scholar). For example, during reperfusion, the reoxygenation of ischemic tissue results in mitochondrial Ca2+ overload and renormalization of intracellular and matrix pH, which are accompanied by the prodigious generation of reactive oxygen species that synergistically induce the opening of the mPTP. Furthermore, both fatty acids and their acyl-CoA derivatives increase dramatically during myocardial ischemia and each greatly facilitate mPTP opening (9Moon S.H. Jenkins C.M. Kiebish M.A. Sims H.F. Mancuso D.J. Gross R.W. Genetic ablation of calcium-independent phospholipase A2γ (iPLA2γ) attenuates calcium-induced opening of the mitochondrial permeability transition pore and resultant cytochrome c release.J. Biol. Chem. 2012; 287: 29837-29850Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar10Furuno T. Kanno T. Arita K. Asami M. Utsumi T. Doi Y. Inoue M. Utsumi K. Roles of long chain fatty acids and carnitine in mitochondrial membrane permeability transition.Biochem. Pharmacol. 2001; 62: 1037-1046Crossref PubMed Scopus (124) Google Scholar, 11Wolkowicz P.E. McMillin-Wood J. Dissociation between mitochondria calcium ion release and pyridine nucleotide oxidation.J. Biol. Chem. 1980; 255: 10348-10353Abstract Full Text PDF PubMed Google Scholar, 12Beatrice M.C. Palmer J.W. Pfeiffer D.R. The relationship between mitochondrial membrane permeability, membrane potential, and the retention of Ca2+ by mitochondria.J. Biol. Chem. 1980; 255: 8663-8671Abstract Full Text PDF PubMed Google Scholar, 13Mittnacht Jr., S. Farber J.L. Reversal of ischemic mitochondrial dysfunction.J. Biol. Chem. 1981; 256: 3199-3206Abstract Full Text PDF PubMed Google Scholar, 14Wojtczak L. Wieckowski M.R. The mechanisms of fatty acid-induced proton permeability of the inner mitochondrial membrane.J. Bioenerg. Biomembr. 1999; 31: 447-455Crossref PubMed Scopus (99) Google Scholar15Penzo D. Petronilli V. Angelin A. Cusan C. Colonna R. Scorrano L. Pagano F. Prato M. Di Lisa F. Bernardi P. Arachidonic acid released by phospholipase A2 activation triggers Ca2+-dependent apoptosis through the mitochondrial pathway.J. Biol. Chem. 2004; 279: 25219-25225Abstract Full Text Full Text PDF PubMed Scopus (145) Google Scholar). The extensive permeability of the inner mitochondrial membrane culminates in the release of proapoptotic factors and the efflux of toxic lipid metabolites into the cytosol that collectively precipitate irreversible myocardial necrosis and apoptosis (10Furuno T. Kanno T. Arita K. Asami M. Utsumi T. Doi Y. Inoue M. Utsumi K. Roles of long chain fatty acids and carnitine in mitochondrial membrane permeability transition.Biochem. Pharmacol. 2001; 62: 1037-1046Crossref PubMed Scopus (124) Google Scholar, 16Halestrap A.P. Richardson A.P. The mitochondrial permeability transition: a current perspective on its identity and role in ischaemia/reperfusion injury.J. Mol. Cell. Cardiol. 2015; 78: 129-141Abstract Full Text Full Text PDF PubMed Scopus (322) Google Scholar, 17Whelan R.S. Konstantinidis K. Wei A.C. Chen Y. Reyna D.E. Jha S. Yang Y. Calvert J.W. Lindsten T. Thompson C.B. Crow M.T. Gavathiotis E. Dorn 2nd, G.W. O'Rourke B. Kitsis R.N. Bax regulates primary necrosis through mitochondrial dynamics.Proc. Natl. Acad. Sci. U.S.A. 2012; 109: 6566-6571Crossref PubMed Scopus (219) Google Scholar). Previously, we identified a novel calcium-independent phospholipase A2γ (iPLA2γ; also known as PNPLA8) that was membrane-associated, present in multiple tissues, and possessed multiple discrete isoforms (18Mancuso D.J. Jenkins C.M. Gross R.W. The genomic organization, complete mRNA sequence, cloning, and expression of a novel human intracellular membrane-associated calcium-independent phospholipase A2.J. Biol. Chem. 2000; 275: 9937-9945Abstract Full Text Full Text PDF PubMed Scopus (179) Google Scholar). Further studies demonstrated that iPLA2γ transcription was tightly regulated through multiple complex mechanisms (19Mancuso D.J. Jenkins C.M. Sims H.F. Cohen J.M. Yang J. Gross R.W. Complex transcriptional and translational regulation of iPLA2γ resulting in multiple gene products containing dual competing sites for mitochondrial or peroxisomal localization.Eur. J. Biochem. 2004; 271: 4709-4724Crossref PubMed Scopus (61) Google Scholar). Through immunohistochemistry and cardiac myocyte-specific expression, iPLA2γ was shown to be localized to mitochondrial and peroxisomal compartments. Transgenic expression of iPLA2γ resulted in the dramatic increase of 2-arachidonoyl lysophosphatidylcholine and 2-docosahexaenoyl lysophosphatidylcholine in cardiac myocytes (19Mancuso D.J. Jenkins C.M. Sims H.F. Cohen J.M. Yang J. Gross R.W. Complex transcriptional and translational regulation of iPLA2γ resulting in multiple gene products containing dual competing sites for mitochondrial or peroxisomal localization.Eur. J. Biochem. 2004; 271: 4709-4724Crossref PubMed Scopus (61) Google Scholar, 20Mancuso D.J. Han X. Jenkins C.M. Lehman J.J. Sambandam N. Sims H.F. Yang J. Yan W. Yang K. Green K. Abendschein D.R. Saffitz J.E. Gross R.W. Dramatic accumulation of triglycerides and precipitation of cardiac hemodynamic dysfunction during brief caloric restriction in transgenic myocardium expressing human calcium-independent phospholipase A2γ.J. Biol. Chem. 2007; 282: 9216-9227Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar). Later studies also identified iPLA2γ in the endoplasmic reticulum (21Eaddy A.C. Cummings B.S. McHowat J. Schnellmann R.G. The role of endoplasmic reticulum Ca2+-independent phospholipase A2γ in oxidant-induced lipid peroxidation, Ca2+ release, and renal cell death.Toxicol. Sci. 2012; 128: 544-552Crossref PubMed Scopus (7) Google Scholar). To begin the mechanistic dissection of the roles of iPLA2γ in biological function in health and disease, we generated a germ line knock-out of iPLA2γ in mice (iPLA2γ KO) (22Mancuso D.J. Sims H.F. Han X. Jenkins C.M. Guan S.P. Yang K. Moon S.H. Pietka T. Abumrad N.A. Schlesinger P.H. Gross R.W. Genetic ablation of calcium-independent phospholipase A2γ leads to alterations in mitochondrial lipid metabolism and function resulting in a deficient mitochondrial bioenergetic phenotype.J. Biol. Chem. 2007; 282: 34611-34622Abstract Full Text Full Text PDF PubMed Scopus (125) Google Scholar, 23Mancuso D.J. Sims H.F. Yang K. Kiebish M.A. Su X. Jenkins C.M. Guan S. Moon S.H. Pietka T. Nassir F. Schappe T. Moore K. Han X. Abumrad N.A. Gross R.W. Genetic ablation of calcium-independent phospholipase A2γ prevents obesity and insulin resistance during high fat feeding by mitochondrial uncoupling and increased adipocyte fatty acid oxidation.J. Biol. Chem. 2010; 285: 36495-36510Abstract Full Text Full Text PDF PubMed Scopus (71) Google Scholar24Mancuso D.J. Kotzbauer P. Wozniak D.F. Sims H.F. Jenkins C.M. Guan S. Han X. Yang K. Sun G. Malik I. Conyers S. Green K.G. Schmidt R.E. Gross R.W. Genetic ablation of calcium-independent phospholipase A2γ leads to alterations in hippocampal cardiolipin content and molecular species distribution, mitochondrial degeneration, autophagy, and cognitive dysfunction.J. Biol. Chem. 2009; 284: 35632-35644Abstract Full Text Full Text PDF PubMed Scopus (78) Google Scholar). These studies revealed that iPLA2γ loss of function dramatically reduced the opening of the mitochondrial permeability transition pore (mPTP) in liver mitochondria and that calcium challenge of myocardial mitochondria obtained from the iPLA2γ KO mouse markedly decreased the production of inflammatory eicosanoids in comparison with wild-type mice. However, germ line iPLA2γ KO mice displayed multiple defects in virtually every organ system studied, thus rendering definitive mechanistic interpretation of responses to in vivo cardiac ischemia difficult. To traverse this difficulty, in this study we generated cardiac myocyte-specific iPLA2γ knock-out mice (CMiPLA2γKO) by inserting flox sites proximal and distal to the active site serine of iPLA2γ (Ser-477 in exon 5) and subsequently excising the exon containing the active site by tamoxifen-activated cardiac myocyte-specific Cre recombinase. Utilizing this novel genetic mouse model, we have investigated the effects of cardiac myocyte-specific KO of iPLA2γ on ischemia/reperfusion in vivo. The regiospecificity of iPLA2γ toward phospholipid substrates is atypical among mammalian PLA2 enzymes in that the site of hydrolysis is dependent on the nature of the sn-2 aliphatic group (25Yan W. Jenkins C.M. Han X. Mancuso D.J. Sims H.F. Yang K. Gross R.W. The highly selective production of 2-arachidonoyl lysophosphatidylcholine catalyzed by purified calcium-independent phospholipase A2γ: identification of a novel enzymatic mediator for the generation of a key branch point intermediate in eicosanoid signaling.J. Biol. Chem. 2005; 280: 26669-26679Abstract Full Text Full Text PDF PubMed Scopus (77) Google Scholar). Specifically, if the sn-2 group is saturated or contains a single double bond, iPLA2γ exhibits no preference for cleavage of the fatty acyl group at the sn-1 or sn-2 position. In sharp contrast, if the sn-2 substituent is polyunsaturated, iPLA2γ serves predominantly as a PLA1 releasing the saturated fatty acid from the sn-1 position and generating 2-polyunsaturated fatty acyl lysolipids. Thus, the regiospecificity of hydrolysis is determined by the degree of unsaturation in the sn-2 phospholipid constituent. This unusual feature allows the enzyme to accomplish multiple regulatory functions in mitochondria, including the release of palmitate in the inner membrane, which opens the mPTP, the generation of polyunsaturated lysophospholipids, which are readily hydrolyzed by endogenous lipases to lead to the production of bioactive oxidized fatty acids (e.g. eicosanoids, docosanoids, etc.), and the provision of fatty acid substrates for use in mitochondrial energy generation. Accordingly, we hypothesized that loss of cardiac iPLA2γ function would decrease I/R injury through a four-tiered synergistic mechanism involving the following: 1) attenuation of mPTP opening; 2) decreased inflammatory lipid second messengers; 3) preservation of mitochondrial membrane potential; and 4) attenuated release of toxic lipid metabolites (e.g. non-esterified saturated fatty acids, lysolipids, acyl-CoAs, and acylcarnitines) that accumulate during myocardial ischemia and are released during reperfusion. In this study, we utilized CMiPLA2γKO mice to investigate iPLA2γ-mediated mPTP opening upon calcium challenge, its role in the production of proinflammatory lipid metabolites (eicosanoids, docosanoids, and oxidized linoleic acid metabolites) in the border zone, and the development of cardiac necrosis after I/R in the absence of the confounding pathologies that were present in the germ line knock-out. Importantly, we demonstrate that myocardial loss of iPLA2γ function substantially reduces infarct size after I/R in vivo and markedly decreases production of inflammatory oxidized fatty acids (oxylipins) in the ischemic border zone. Through ablation of iPLA2γ-facilitated mPTP opening, generation of inflammatory lipid second messengers, and the release of toxic mitochondrial metabolites, a novel strategy to attenuate cardiac necrosis and inflammation during acute coronary syndromes has been identified. To definitively identify the mechanistic importance of iPLA2γ in cardiac myocytes, we engineered an inducible cardiac myocyte-specific knock-out of iPLA2γ. Because of the presence of multiple transcriptional start sites in iPLA2γ, our strategy was to flox exon 5 containing the active site and remove it by tamoxifen induction of cardiac myocyte-specific Cre recombinase (Fig. 1). Southern analysis for the floxed iPLA2γ allele in multiple tissues of the f/f mouse and PCR analyses for the identification of ablation of the PGK-neo cassette and iPLA2γf/f Cre+ in the iPLA2γ conditional KO mice are shown in Fig. 1. Northern and Western analyses demonstrated the specific ablation of iPLA2γ in heart but not in other tissues in the CMiPLA2γKO mouse (Fig. 1, E and F). Myocardium is composed of multiple cell types, including cardiac myocytes, endothelial cells, smooth muscle cells, fibroblasts, and macrophages. Although myocardium contains substantial amounts of iPLA2γ activity and protein, the cell type of origin of iPLA2γ is not known with certainty. Comparisons of WT Cre+ with CMiPLA2γKO mice definitively demonstrate that the overwhelming majority of iPLA2γ protein of murine myocardium is present in cardiac myocytes by tissue-specific knock-out mediated by the specificity of cardiac myocyte-specific expression of Cre recombinase. Moreover, the results of Fig. 1F demonstrate the diverse tissue-specific distribution of iPLA2γ isoforms (e.g. 88, 74, 63, and 52 kDa), which were previously identified by germ line knock-out and transgenic overexpression of iPLA2γ (9Moon S.H. Jenkins C.M. Kiebish M.A. Sims H.F. Mancuso D.J. Gross R.W. Genetic ablation of calcium-independent phospholipase A2γ (iPLA2γ) attenuates calcium-induced opening of the mitochondrial permeability transition pore and resultant cytochrome c release.J. Biol. Chem. 2012; 287: 29837-29850Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar, 19Mancuso D.J. Jenkins C.M. Sims H.F. Cohen J.M. Yang J. Gross R.W. Complex transcriptional and translational regulation of iPLA2γ resulting in multiple gene products containing dual competing sites for mitochondrial or peroxisomal localization.Eur. J. Biochem. 2004; 271: 4709-4724Crossref PubMed Scopus (61) Google Scholar, 20Mancuso D.J. Han X. Jenkins C.M. Lehman J.J. Sambandam N. Sims H.F. Yang J. Yan W. Yang K. Green K. Abendschein D.R. Saffitz J.E. Gross R.W. Dramatic accumulation of triglycerides and precipitation of cardiac hemodynamic dysfunction during brief caloric restriction in transgenic myocardium expressing human calcium-independent phospholipase A2γ.J. Biol. Chem. 2007; 282: 9216-9227Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar). For example, note the predominance of the lower molecular mass iPLA2γ isoforms (50–60 kDa) in liver in comparison with myocardium and brain. Collectively, these results demonstrate that iPLA2γ in myocardium is predominantly located in cardiac myocytes and identify the tissue-specific distributions of different isoforms of iPLA2γ. In contrast to the global iPLA2γ knock-out, which demonstrated a thin body habitus, decreased length, cognitive dysfunction, kyphosis, and decreased locomotor activity (22Mancuso D.J. Sims H.F. Han X. Jenkins C.M. Guan S.P. Yang K. Moon S.H. Pietka T. Abumrad N.A. Schlesinger P.H. Gross R.W. Genetic ablation of calcium-independent phospholipase A2γ leads to alterations in mitochondrial lipid metabolism and function resulting in a deficient mitochondrial bioenergetic phenotype.J. Biol. Chem. 2007; 282: 34611-34622Abstract Full Text Full Text PDF PubMed Scopus (125) Google Scholar, 24Mancuso D.J. Kotzbauer P. Wozniak D.F. Sims H.F. Jenkins C.M. Guan S. Han X. Yang K. Sun G. Malik I. Conyers S. Green K.G. Schmidt R.E. Gross R.W. Genetic ablation of calcium-independent phospholipase A2γ leads to alterations in hippocampal cardiolipin content and molecular species distribution, mitochondrial degeneration, autophagy, and cognitive dysfunction.J. Biol. Chem. 2009; 284: 35632-35644Abstract Full Text Full Text PDF PubMed Scopus (78) Google Scholar), the CMiPLA2γKO mice gained weight normally, possessed normal insulin sensitivity, did not develop kyphosis, and had no demonstrable sensory-motor abnormalities (data not shown). Echocardiographic analyses of myocardial hemodynamic function in the CMiPLA2γKO mice at 6 months of age (3 months after tamoxifen administration) revealed no significant alterations in left ventricular wall thickness, left ventricular mass index, or chamber diameters during end systole/diastole and displayed normal fractional shortening in comparison with WT littermates (Table 1).TABLE 1Echocardiographic analysis of myocardial hemodynamic function in wild-type (WT) and cardiac myocyte-specific iPLA2γ knock-out (KO) mice under light anesthesiaTypeBody wtHRLVPWdIVSdLVIDdLVPWIVSLVIDLVMLVMIRWTFSgbeats/minmmmmmmmmmmmmmg%WT30.3±1.7638.7±51.80.93±0.060.99±0.043.59±0.251.56±0.201.67±0.141.60±0.20124.7±9.44.12±0.280.54±0.0555.3±5.0KO31.2±2.9651.0±11.80.95±0.060.96±0.033.72±0.251.63±0.141.68±0.121.59±0.24131.1±7.64.22±0.340.51±0.0657.2±4.9 Open table in a new tab High resolution respirometry of myocardial mitochondria was performed to identify alterations in mitochondrial function and respiratory coupling efficiency in CMiPLA2γKO mice. To examine mitochondrial bioenergetic efficiency under different conditions, we utilized multiple substrates, including pyruvate/malate, palmitoylcarnitine/malate, and pyruvate/glutamate/malate. Mitochondria from CMiPLA2γKO mice demonstrated similar oxygen consumption rates in comparison with WT littermates during both state 2 and 3 respiration or after inhibition of complex I (rotenone) or complex V (oligomycin-induced state 4) (Fig. 2). The coupling of electron transport to oxidative phosphorylation (P/O ratio), which was determined by quantifying ATP production and O2 consumption during state 3 respiration, was not significantly different in WT versus CMiPLA2γKO mice (Fig. 2). These results demonstrate the ability of mitochondria from the CMiPLA2γKO to respire normally and efficiently synthesize ATP. To determine alterations in the myocardial lipidome of WT versus CMiPLA2γKO mice, we utilized multidimensional mass spectrometry-based shotgun lipidomics (MDMS-SL) (26Han X. Yang K. Gross R.W. Multi-dimensional mass spectrometry-based shotgun lipidomics and novel strategies for lipidomic analyses.Mass Spectrom. Rev. 2012; 31: 134-178Crossref PubMed Scopus (418) Google Scholar). The major phospholipid classes in myocardium are choline and ethanolamine glycerophospholipids. Examination of choline glycerophospholipids demonstrated the presence of over 45 molecular species in murine myocardium that were largely composed of diacyl (D) phosphatidylcholine molecular species containing D16:0–22:6/D18:2–20:4, D18:0–22:6, D16:0–20:4/D18:2–18:2, D18:2–22:6, and D18:0–20:4/D18:2–20:2 in both the WT and the CMiPLA2γKO mice. Mirror plots of choline glycerophospholipids from averaged tandem mass spectra collected from six different mice demonstrated nearly identical profiles of individual molecular species (Fig. 3A). Similarly, MDMS-SL analysis of ethanolamine glycerophospholipids demonstrated over 30 diacyl phosphatidylethanolamine molecular species largely composed of D18:0–22:6, D16:0–22:6, D18:1–22:6, and D18:0–20:4 molecular species as well as 20 plasmenyl (P) ethanolamine phospholipid molecular species largely composed of P16:0–22:6, P18:1–20:4/P16:0–22:5, P18:0–22:6, and P18:1–22:6 molecular species. Mirror plots of ethanolamine glycerophospholipids from averaged mass spectra from six separate mice did not identify any significant differences between WT and CMiPLA2γKO mouse hearts (Fig. 3B). Triglyceride analysis by MDMS-SL demonstrated nearly identical total amounts of triglycerides and no differences in their molecular species composition in WT versus CMiPLA2γKO mice (Fig. 3C). Negative ion mass spectra did not reveal any significant differences in phosphatidylinositol, phosphatidylserine, or phosphatidylglycerol molecular species (Fig. 3D). Next, because tetra-18:2 cardiolipin (CL) has been previously proposed to enhance mitochondrial efficiency by stabilizing the formation of mitochondrial supercomplexes (27Chicco A.J. Sparagna G.C. Role of cardiolipin alterations in mitochondrial dysfunction and disease.Am. J. Physiol. Cell Physiol. 2007; 292: C33-C44Crossref PubMed Scopus (493) Google Scholar28Chicco A.J. Sparagna G.C. McCune S.A. Johnson C.A. Murphy R.C. Bolden D.A. Rees M.L. Gardner R.T. Moore R.L. Linoleate-rich high-fat diet decreases mortality in hypertensive heart failure rats compared with lard and low-fat diets.Hypertension. 2008; 52: 549-555Crossref PubMed Scopus (51) Google Scholar, 29Kiebish M.A. Yang K. Sims H.F. Jenkins C.M. Liu X. Mancuso D.J. Zhao Z. Guan S. Abendschein D.R. Han X. Gross R.W. Myocardial regulation of lipidomic flux by cardiolipin synthase: setting the beat for bioenergetic efficiency.J. Biol. Chem. 2012; 287: 25086-25097Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar30Mulligan C.M. Sparagna G.C. Le C.H. De Mooy A.B. Routh M.A. Holmes M.G. Hickson-Bick D.L. Zarini S. Murphy R.C. Xu F.Y. Hatch G.M. McCune S.A. Moore R.L. Chicco A.J. Dietary linoleate preserves cardiolipin and attenuates mitochondrial dysfunction in the failing rat heart.Cardiovasc. Res. 2012; 94: 460-468Crossref PubMed Scopus (44) Google Scholar), we determined the content and composition of myocardial CL using the M+1/2 isotopologue approach (Fig. 4) (31Han X. Yang K. Yang J. Cheng H. Gross R.W. Shotgun lipidomics of cardiolipin molecular species in lipid extracts of biological samples.J. Lipid Res. 2006; 47: 864-879Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar). The results demonstrated no significant differences in the total content of CL. The composition of most molecular species of CL, including symmetric tetra-18:2 CL (m/z 723.5 in Fig. 4A) in WT versus CMiPLA2γKO myocardium, were nearly identical. Modest decreases in the levels of 18:2–18:2–18:2–22:6 CL and 18:2–18:2–22:6–22:6 CL (m/z 747.5 and m/z 771.5, respectively, in Fig. 4A) were present in CMiPLA2γKO mice (Fig. 4B). Previous studies have demonstrated the important roles of iPLA2γ in releasing polyunsaturated fatty acids from mitochondria that are subsequently oxidized by a wide variety of downstream oxygenases (32Yoda E. Hachisu K. Taketomi Y. Yoshida K. Nakamura M. Ikeda K. Taguchi R. Nakatani Y. Kuwata H. Murakami M. Kudo I. Hara S. Mitochondrial dysfunction and reduced prostaglandin synthesis in skeletal muscle of Group VIB Ca2+-independent phospholipase A2γ-deficient mice.J. Lipid Res. 2010; 51: 3003-3015Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar33Sharma J. McHowat J. PGE2 release from tryptase-stimulated rabbit ventricular myocytes is mediated by calcium-independent phospholipase A2γ.Lipids. 2011; 46: 391-397Crossref PubMed Scopus (8) Google Scholar, 34Moon S.H. Jenkins C.M. Liu X. Guan S. Mancuso D.J. Gross R.W. Activation of mitochondrial calcium-independent phospholipase A2γ (iPLA2γ) by divalent cations mediating arachidonate" @default.
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• W2513244497 title "Cardiac Myocyte-specific Knock-out of Calcium-independent Phospholipase A2γ (iPLA2γ) Decreases Oxidized Fatty Acids during Ischemia/Reperfusion and Reduces Infarct Size" @default.
• W2513244497 cites W134684325 @default.
• W2513244497 cites W1496479559 @default.
• W2513244497 cites W1536035248 @default.
• W2513244497 cites W1549466745 @default.
• W2513244497 cites W1607777232 @default.
• W2513244497 cites W1673932087 @default.
• W2513244497 cites W1976348423 @default.
• W2513244497 cites W1977221909 @default.
• W2513244497 cites W1977595115 @default.
• W2513244497 cites W1982994793 @default.
• W2513244497 cites W1983617509 @default.
• W2513244497 cites W1986179656 @default.
• W2513244497 cites W2000864465 @default.
• W2513244497 cites W2001993009 @default.
• W2513244497 cites W2012988962 @default.
• W2513244497 cites W2016079109 @default.
• W2513244497 cites W2017711362 @default.
• W2513244497 cites W2023039726 @default.
• W2513244497 cites W2029370462 @default.
• W2513244497 cites W2037242261 @default.
• W2513244497 cites W2040238011 @default.
• W2513244497 cites W2040913240 @default.
• W2513244497 cites W2041264206 @default.
• W2513244497 cites W2043081679 @default.
• W2513244497 cites W2043355876 @default.
• W2513244497 cites W2043614277 @default.
• W2513244497 cites W2047322721 @default.
• W2513244497 cites W2049018086 @default.
• W2513244497 cites W2049298036 @default.
• W2513244497 cites W2051395985 @default.
• W2513244497 cites W2052894996 @default.
• W2513244497 cites W2057622336 @default.
• W2513244497 cites W2059323997 @default.
• W2513244497 cites W2059544508 @default.
• W2513244497 cites W2065150396 @default.
• W2513244497 cites W2067143095 @default.
• W2513244497 cites W2074357838 @default.
• W2513244497 cites W2079341775 @default.
• W2513244497 cites W2080721744 @default.
• W2513244497 cites W2088901531 @default.
• W2513244497 cites W2101841000 @default.
• W2513244497 cites W2103010344 @default.
• W2513244497 cites W2117977069 @default.
• W2513244497 cites W2119486534 @default.
• W2513244497 cites W2121986747 @default.
• W2513244497 cites W2124114189 @default.
• W2513244497 cites W2128916765 @default.
• W2513244497 cites W2129585784 @default.
• W2513244497 cites W2129849952 @default.
• W2513244497 cites W2135091756 @default.
• W2513244497 cites W2143046500 @default.
• W2513244497 cites W2152061367 @default.
• W2513244497 cites W2153619230 @default.
• W2513244497 cites W2156979985 @default.
• W2513244497 cites W2159939354 @default.
• W2513244497 cites W2169006029 @default.
• W2513244497 cites W2169957088 @default.
• W2513244497 cites W2170347547 @default.
• W2513244497 cites W2254382629 @default.
• W2513244497 cites W2402438269 @default.
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