A pore way to die: the role of mitochondria in reperfusion injury and cardioprotection

2010 ◽  
Vol 38 (4) ◽  
pp. 841-860 ◽  
Author(s):  
Andrew P. Halestrap
Keyword(s):  
Oxidative Stress ◽  
Reperfusion Injury ◽  
Mitochondrial Membrane ◽  
Heart Surgery ◽  
Mitochondrial Permeability Transition ◽  
Adenine Nucleotide ◽  
Physiological Role ◽  
Dark Side ◽  
Cyclophilin D ◽  
Mptp Opening

In addition to their normal physiological role in ATP production and metabolism, mitochondria exhibit a dark side mediated by the opening of a non-specific pore in the inner mitochondrial membrane. This mitochondrial permeability transition pore (MPTP) causes the mitochondria to breakdown rather than synthesize ATP and, if unrestrained, leads to necrotic cell death. The MPTP is opened in response to Ca2+ overload, especially when accompanied by oxidative stress, elevated phosphate concentration and adenine nucleotide depletion. These conditions are experienced by the heart and brain subjected to reperfusion after a period of ischaemia as may occur during treatment of a myocardial infarction or stroke and during heart surgery. In the present article, I review the properties, regulation and molecular composition of the MPTP. The evidence for the roles of CyP-D (cyclophilin D), the adenine nucleotide translocase and the phosphate carrier are summarized and other potential interactions with outer mitochondrial membrane proteins are discussed. I then review the evidence that MPTP opening mediates cardiac reperfusion injury and that MPTP inhibition is cardioprotective. Inhibition may involve direct pharmacological targeting of the MPTP, such as with cyclosporin A that binds to CyP-D, or indirect inhibition of MPTP opening such as with preconditioning protocols. These invoke complex signalling pathways to reduce oxidative stress and Ca2+ load. MPTP inhibition also protects against congestive heart failure in hypertensive animal models. Thus the MPTP is a very promising pharmacological target for clinical practice, especially once more specific drugs are developed.

Calcium, mitochondria and reperfusion injury: a pore way to die

2006 ◽  
Vol 34 (2) ◽  
pp. 232-237 ◽  
Author(s):  
A.P. Halestrap
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Reperfusion Injury ◽  
Mitochondrial Permeability Transition ◽  
Adenine Nucleotide ◽  
Coronary Thrombosis ◽  
Permeability Transition ◽  
Cyclophilin D ◽  
Inner Mitochondrial Membrane ◽  
Apoptotic Pathway

When mitochondria are exposed to high Ca2+ concentrations, especially when accompanied by oxidative stress and adenine nucleotide depletion, they undergo massive swelling and become uncoupled. This occurs as a result of the opening of a non-specific pore in the inner mitochondrial membrane, known as the MPTP (mitochondrial permeability transition pore). If the pore remains open, cells cannot maintain their ATP levels and this will lead to cell death by necrosis. This article briefly reviews what is known of the molecular mechanism of the MPTP and its role in causing the necrotic cell death of the heart and brain that occurs during reperfusion after a long period of ischaemia. Such reperfusion injury is a major problem during cardiac surgery and in the treatment of coronary thrombosis and stroke. Prevention of MPTP opening either directly, using agents such as cyclosporin A, or indirectly by reducing oxidative stress or Ca2+ overload, provides a protective strategy against reperfusion injury. Furthermore, mice in which a component of the MPTP, CyP-D (cyclophilin D), has been knocked out are protected against heart and brain ischaemia/reperfusion. When cells experience a less severe insult, the MPTP may open transiently. The resulting mitochondrial swelling may be sufficient to cause release of cytochrome c and activation of the apoptotic pathway rather than necrosis. However, the CyP-D-knockout mice develop normally and show no protection against a range of apoptotic stimuli, suggesting that the MPTP does not play a role in most forms of apoptosis.

Abstract 168: Resveratrol Translocates Gsk-3β To Mitochondria And Protects The Heart At Reperfusion By Targeting The Mitochondrial Permeability Transition Pore

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Jinkun Xi ◽  
Huihua Wang ◽  
Guillaume Chanoit ◽  
Guang Cheng ◽  
Robert A Mueller ◽  
...  
Keyword(s):  
Reperfusion Injury ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Cyclophilin D ◽  
Risk Zone ◽  
Mitochondrial Permeability ◽  
Mptp Opening ◽  
Gsk 3Β

Although resveratrol has been demonstrated to be cardioprotective, the detailed cellular and molecular mechanisms that mediate the protection remain elusive. We aimed to determine if resveratrol protects the heart at reperfusion by modulating the mitochondrial permeability transition pore (mPTP) opening through glycogen synthase kinase 3β (GSK-3β). Resveratrol (10μM) given at reperfusion reduced infarct size (12.2 ± 2.5 % of risk zone vs. 37.9 ± 3.1 % of risk zone in control, n = 6) in isolated rat hearts subjected to 30 min regional ischemia followed by 2 h of reperfusion, an effect that was abrogated by the mPTP opener atractyloside (30.9 ± 8.1 % of risk zone), implying that resveratrol may protect the heart at reperfusion by modulating the mPTP opening. To define the signaling mechanism underlying the action of resveratrol, we determined GSK-3β activity by measuring its phosphorylation at Ser 9 . Resveratrol significantly enhanced GSK-3β phosphorylation upon reperfusion (225.2 ± 30.0 % of control at 5 min of reperfusion). Further experiments showed that resveratrol induces translocation of GSK-3β to mitochondria and translocated GSK-3β interacts with the mPTP component cyclophilin D but not VDAC (the voltage-dependent anion channel) or ANT (the adenine nucleotide translocator) in cardiac mitochondria. Taken together, these data suggest that resveratrol prevents myocardial reperfusion injury by targeting the mPTP opening via GSK-3β. Translocation of GSK-3β to mitochondria and its interaction with the mPTP component cyclophilin D may serve as an essential mechanism that mediates the protective effect of resveratrol on reperfusion injury.

scholarly journals Cyclophilin-D promotes the mitochondrial permeability transition but has opposite effects on apoptosis and necrosis

2004 ◽  
Vol 383 (1) ◽  
pp. 101-109 ◽  
Author(s):  
Yanmin LI ◽  
Nicholas JOHNSON ◽  
Michela CAPANO ◽  
Mina EDWARDS ◽  
Martin CROMPTON
Keyword(s):  
Oxidative Stress ◽  
Cell Injury ◽  
Mitochondrial Permeability Transition ◽  
Adenine Nucleotide ◽  
Permeability Transition ◽  
Cyclophilin D ◽  
Intact Cells ◽  
Inner Membrane ◽  
Mitochondrial Permeability ◽  
Apoptosis And Necrosis

Cyclophilin-D is a peptidylprolyl cis–trans isomerase of the mitochondrial matrix. It is involved in mitochondrial permeability transition, in which the adenine nucleotide translocase of the inner membrane is transformed from an antiporter to a non-selective pore. The permeability transition has been widely considered as a mechanism in both apoptosis and necrosis. The present study examines the effects of cyclophilin-D on the permeability transition and lethal cell injury, using a neuronal (B50) cell line stably overexpressing cyclophilin-D in mitochondria. Cyclophilin-D overexpression rendered isolated mitochondria far more susceptible to the permeability transition induced by Ca2+ and oxidative stress. Similarly, cyclophilin-D overexpression brought forward the onset of the permeability transition in intact cells subjected to oxidative stress. In addition, in the absence of stress, the mitochondria of cells overexpressing cyclophilin-D maintained a lower inner-membrane potential than those of normal cells. All these effects of cyclophilin-D overexpression were abolished by cyclosporin A. It is concluded that cyclophilin-D promotes the permeability transition in B50 cells. However, cyclophilin-D overexpression had opposite effects on apoptosis and necrosis; whereas NO-induced necrosis was promoted, NO- and staurosporine-induced apoptosis were inhibited. These findings indicate that the permeability transition leads to cell necrosis, but argue against its involvement in apoptosis.

Abstract P237: Exercise Training Prevents Hypercholesterolemia-Induced Cardiac Mitochondrial Dysfunction

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Allison M McGee ◽  
Kyle S McCommis ◽  
M H Laughlin ◽  
Douglas K Bowles ◽  
Christopher P Baines
Keyword(s):  
Oxidative Stress ◽  
Exercise Training ◽  
Manganese Superoxide Dismutase ◽  
Mitochondrial Permeability Transition ◽  
Adenine Nucleotide ◽  
Permeability Transition ◽  
Exercise Group ◽  
Ros Generation ◽  
Cyclophilin D ◽  
Negative Effects

Hypercholesterolemia has been suggested to have direct negative effects on myocardial function due to increased reactive oxygen species (ROS) generation and increased myocyte death. Mitochondrial permeability transition (MPT) is a significant mediator of cell death, which is enhanced by ROS generation and attenuated by exercise training. The purpose of this study was to investigate the effect of hypercholesterolemia on the MPT response of cardiac mitochondria. We hypothesized that familial hypercholesterolemic (FH) pigs would have an enhanced MPT response, and that exercise training could reverse this phenotype. FH pigs were obtained from the University of Wisconsin. Control, normolipidemic farm pigs were maintained on standard pig chow. After 4 months on a high-fat diet, the FH pigs were switched to the standard pig chow, and randomized to sedentary or exercise groups. The exercise group underwent a progressive treadmill-based training program for 4 months. At the end of the training protocol the animals were sacrificed and the heart removed. MPT was assessed by mitochondrial swelling in response to Ca2+. Protein nitrotyrosylation, GSH levels, and antioxidant enzyme expression were also examined. FH pigs did show an increased MPT response despite no change in the expression of putative MPT pore components adenine nucleotide translocase (ANT), mitochondrial phosphate carrier (PiC), and cyclophilin-D (CypD). FH also caused increased oxidative stress, depicted by increased protein nitrotyrosylation and decreased GSH levels. This was associated with concomitant decreases in the expression of mitochondrial antioxidant enzymes manganese superoxide dismutase (MnSOD) and thioredoxin-2 (Trx2). However, chronic exercise training was able to normalize the MPT response in FH pigs, reduce oxidative stress, and increase MnSOD expression. We conclude that hypercholesterolemia causes increased oxidative stress and enhances the MPT response in the porcine myocardium, and that exercise training can correct for both the increased oxidative stress and MPT alterations observed with hypercholesterolemia.

Mitochondria and cell death

2000 ◽  
Vol 28 (2) ◽  
pp. 170-177 ◽  
Author(s):  
A. P. Halestrap ◽  
E. Doran ◽  
J. P. Gillespie ◽  
A. O'Toole
Keyword(s):  
Cell Death ◽  
Outer Membrane ◽  
Mitochondrial Permeability Transition ◽  
Adenine Nucleotide ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Cyclophilin D ◽  
Ischaemia Reperfusion Injury ◽  
Mptp Opening ◽  
Cyt C

Mitochondria play a central role in both apoptosis and necrosis through the opening of the mitochondrial permeability transition pore (MPTP). This is thought to be formed through a Ca2+-triggered conformational change of the adenine nucleotide translocase (ANT) bound to matrix cyclophilin-D and we have now demonstrated this directly by reconstitution of the pure components. Opening of the MPTP causes swelling and uncoupling of mitochondria which, unrestrained, leads to necrosis. In ischaemia/reperfusion injury of the heart we have shown MPTP opening directly. Recovery of hearts correlates with subsequent closure, and agents that prevent opening or enhance closure protect from injury. Transient MPTP opening may also be involved in apoptosis by initially causing swelling and rupture of the outer membrane to release cytochrome c (cyt c), which then activates the caspase cascade and sets apoptosis in motion. Subsequent MPTP closure allows ATP levels to be maintained, ensuring that cell death remains apoptotic rather than necrotic. Apoptosis in the hippocampus that occurs after a hypoglycaemic or ischaemic insult is triggered by this means. Other apoptotic stimuli such as cytokines or removal of growth factors also involve mitochondrial cyt c release, but here there is controversy over whether the MPTP is involved. In many cases cyt c release is seen without any mitochondrial depolarization, suggesting that the MPTP does not open. Recent data of our own and others have revealed a specific outer-membrane cyt c-release pathway involving porin that does not release other intermembrane proteins such as adenylate kinase. This is opened by pro-apototic members of the Bcl-2 family such as BAX and prevented by anti-apoptotic members such as Bcl-xL. Our own data suggest that this pathway may interact directly with the ANT in the inner membrane at contact sites.

The mitochondrial permeability transition: its molecular mechanism and role in reperfusion injury

1999 ◽  
Vol 66 ◽  
pp. 181-203 ◽  
Author(s):  
Andrew P. Halestrap
Keyword(s):  
Oxidative Stress ◽  
Cyclosporin A ◽  
Reperfusion Injury ◽  
Molecular Mechanism ◽  
Mitochondrial Permeability Transition ◽  
Adenine Nucleotide ◽  
Apoptotic Cell ◽  
Heart Function ◽  
Permeability Transition ◽  
Mitochondrial Permeability

The mitochondrial permeability transition (mPT) involves the opening of a non-specific pore in the inner membrane of mitochondria, converting them from organelles whose production of ATP sustains the cell, to instruments of death. Here, I first summarize the evidence in favour of our model for the molecular mechanism of the mPT. It is proposed that the adenine nucleotide translocase (ANT) is converted into a non-specific pore through a calcium-mediated conformational change. This requires the binding of a unique cyclophilin (cyclophilin-D, CyP-D) to the ANT, except when matrix [Ca2+] is very high. Binding of CyP-D is increased in response to oxidative stress and some thiol reagents which sensitize the mPT to [Ca2+]. Matrix adenine nucleotides decrease the sensitivity of the mPT to [Ca2+] by binding to the ANT. This is antagonized by carboxyatractyloside (an inhibitor of the ANT) and by modification of specific thiol groups on the ANT by oxidative stress or thiol reagents; such treatments thus enhance the mPT. In contrast, decreasing intracellular pH below 7.0 greatly desensitizes the mPT to [Ca2+]. Conditions which sensitize the mPT towards [Ca2+] are found in hearts reperfused after a period of ischaemia, a process that may irreversibly damage the heart (reperfusion injury). We have demonstrated directly that mPT pores open during reperfusion (but not ischaemia) using a technique that involves entrapment of [3H]deoxyglucose in mitochondria that have undergone the mPT. The mPT may subsequently reverse in hearts that recover from ischaemia/reperfusion, the extent of resealing correlating with recovery of heart function. A variety of agents that antagonize the mPT protect the heart from reperfusion injury, including cyclosporin A, pyruvate and propofol. Mitochondria that undergo the mPT and then reseal may cause cytochrome c release and thus initiate apoptosis in cells subjected to stresses less severe than those causing necrosis. An example is the apoptotic cell death in the hippocampus that occurs several days after insulin-induced hypoglycaemia, and can be prevented by prior treatment with cyclosporin A.

Abstract 5420: Dephosphorylation of the Cardiac Mitochondrial Voltage-Dependent Anion Channel Prevents Inhibition by Hexokinase

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Qunli Cheng ◽  
Zeljko J Bosnjak ◽  
Wai-Meng Kwok
Keyword(s):  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition ◽  
Adenine Nucleotide ◽  
Standard Procedure ◽  
Anion Channel ◽  
Mitochondrial Outer Membrane ◽  
Cyclophilin D ◽  
Voltage Dependent Anion Channel ◽  
Voltage Dependent ◽  
The Mean

The mitochondrial permeability transition pore (mPTP) has been implicated as the end effector in ischemic and pharmacological preconditioning. Though the molecular composition of the mPTP is thought to consist of cyclophilin D located in the mitochondrial matrix, adenine nucleotide translocase on the inner mitochondrial membrane, and the voltage-dependent anion channel (VDAC) on the outer mitochondrial membrane, recent studies have raised the possibility that VDAC may be a regulatory, rather than a major, component of mPTP. Nevertheless, VDAC is likely to be a critical component of the preconditioning signaling pathway since it is the main conduit for metabolite diffusion across the mitochondrial outer membrane. Yet, the direct measurements of cardiac VDAC activity and modulation have been limited. In the present study, we purified VDAC from rat hearts using standard procedure and investigated its modulation by phosphatase and hexokinase. VDAC was incorporated into planar lipid bilayer for measurements of channel activities. The channel exhibited the reported voltage-dependent gating. Several conductance states were identified, with the most prevalent between 1.5 to 2 nS in 0.5 M NaCl. Koenig’s polyanion, a VDAC blocker, triggered channel flickering and decreased the mean current by 78±6%. In the presence of phosphatase (1 unit/ml), the mean conductance significantly increased from 1.81±0.03 to 3.68±0.61 nS (n=9; mean±SEM). However, the addition of a recombinant hexokinase (5 units/ml; GenWay Biotech) had no significant effect on the phosphatase-enhanced VDAC current (n=4). In contrast, recombinant hexokinase alone significantly decreased the mean conductance from 1.75±0.05 to 0.79±0.19 nS (n=4). The addition of phosphatase reversed the inhibitory effect of hexokinase and further enhanced VDAC activity, increasing the mean conductance to 2.69±0.19 nS (n=4). Our results suggest that the dephosphorylation of VDAC prevents the inhibitory effects of hexokinase. Furthermore, VDAC activity suppressed by hexokinase can be reversed by dephosphorylation of the channel. In conclusion, we have reported on a novel observation at the functional level that basal phosphorylation of the cardiac VDAC may be required for its modulation by hexokinase.

scholarly journals Adenine Nucleotide Translocase-1, a Component of the Permeability Transition Pore, Can Dominantly Induce Apoptosis

1999 ◽  
Vol 147 (7) ◽  
pp. 1493-1502 ◽  
Author(s):  
Manuel K.A. Bauer ◽  
Alexis Schubert ◽  
Oliver Rocks ◽  
Stefan Grimm
Keyword(s):  
Cell Death ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition ◽  
Adenine Nucleotide ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Adenine Nucleotide Translocase ◽  
Cyclophilin D ◽  
Protein Aggregate ◽  
Cytochrome C Release

Here, we describe the isolation of adenine nucleotide translocase-1 (ANT-1) in a screen for dominant, apoptosis-inducing genes. ANT-1 is a component of the mitochondrial permeability transition complex, a protein aggregate connecting the inner with the outer mitochondrial membrane that has recently been implicated in apoptosis. ANT-1 expression led to all features of apoptosis, such as phenotypic alterations, collapse of the mitochondrial membrane potential, cytochrome c release, caspase activation, and DNA degradation. Both point mutations that impair ANT-1 in its known activity to transport ADP and ATP as well as the NH2-terminal half of the protein could still induce apoptosis. Interestingly, ANT-2, a highly homologous protein could not lead to cell death, demonstrating the specificity of the signal for apoptosis induction. In contrast to Bax, a proapoptotic Bcl-2 gene, ANT-1 was unable to elicit a form of cell death in yeast. This and the observed repression of apoptosis by the ANT-1–interacting protein cyclophilin D suggest that the suicidal effect of ANT-1 is mediated by specific protein–protein interactions within the permeability transition pore.

scholarly journals Urocortin prevents mitochondrial permeability transition in response to reperfusion injury indirectly by reducing oxidative stress

2007 ◽  
Vol 293 (2) ◽  
pp. H928-H938 ◽  
Author(s):  
Paul A. Townsend ◽  
Sean M. Davidson ◽  
Samantha J. Clarke ◽  
Igor Khaliulin ◽  
Christopher J. Carroll ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Reperfusion Injury ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Neonatal Rat ◽  
Ischemia And Reperfusion Injury ◽  
Mitochondrial Permeability ◽  
Lactate Dehydrogenase Release ◽  
Mptp Opening

Urocortin (UCN) protects hearts against ischemia and reperfusion injury whether given before ischemia or at reperfusion. Here we investigate the roles of PKC, reactive oxygen species, and the mitochondrial permeability transition pore (MPTP) in mediating these effects. In Langendorff-perfused rat hearts, acute UCN treatment improved hemodynamic recovery during reperfusion after 30 min of global ischemia; this was accompanied by less necrosis (lactate dehydrogenase release) and MPTP opening (mitochondrial entrapment of 2-[3H]deoxyglucose). UCN pretreatment protected mitochondria against calcium-induced MPTP opening, but only if the mitochondria had been isolated from hearts after reperfusion. These mitochondria also exhibited less protein carbonylation, suggesting that UCN decreases levels of oxidative stress. In isolated adult and neonatal rat cardiac myocytes, both acute (60 min) and chronic (16 h) treatment with UCN reduced cell death following simulated ischemia and re-oxygenation. This was accompanied by less MPTP opening as measured using tetramethylrhodamine methyl ester. The level of oxidative stress during reperfusion was reduced in cells that had been pretreated with UCN, suggesting that this is the mechanism by which UCN desensitizes the MPTP to reperfusion injury. Despite the fact that we could find no evidence that either PKC-ε or PKC-α translocate to the mitochondria following acute UCN treatment, inhibition of PKC with chelerythrine eliminated the effect of UCN on oxidative stress. Our data suggest that acute UCN treatment protects the heart by inhibiting MPTP opening. However, the mechanism appears to be indirect, involving a PKC-mediated reduction in oxidative stress.

Chronic Tempol treatment restores pharmacological preconditioning in the senescent rat heart

2013 ◽  
Vol 304 (5) ◽  
pp. H649-H659 ◽  
Author(s):  
Jiang Zhu ◽  
Mario J. Rebecchi ◽  
Qiang Wang ◽  
Peter S. A. Glass ◽  
Peter R. Brink ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Permeability Transition Pore ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Cyclophilin D ◽  
Mitochondrial Permeability ◽  
Anesthetic Preconditioning ◽  
Permeability Transition Pore Opening ◽  
Pore Opening

Cardioprotective effects of anesthetic preconditioning and cyclosporine A (CsA) are lost with aging. To extend our previous work and address a possible mechanism underlying age-related differences, we investigated the role of oxidative stress in the aging heart by treating senescent animals with the oxygen free radical scavenger Tempol. Old male Fischer 344 rats (22–24 mo) were randomly assigned to control or Tempol treatment groups for 2 or 4 wk (T×2wk and T×4wk, respectively). Rats received isoflurane 30 min before ischemia-reperfusion injury or CsA just before reperfusion. Myocardial infarction sizes were significantly reduced by isoflurane or CsA in the aged rats treated with Tempol (T×4wk) compared with old control rats. In other experiments, young (4–6 mo) and old rats underwent either chronic Tempol or vehicle treatment, and the levels of myocardial protein oxidative damage, antioxidant enzymes, mitochondrial Ca2+ uptake, cyclophilin D protein, and mitochondrial permeability transition pore opening times were measured. T×4wk significantly increased MnSOD enzyme activity, GSH-to-GSSH ratios, MnSOD protein level, mitochondrial Ca2+ uptake capacity, reduced protein nitrotyrosine levels, and normalized cyclophilin D protein expression in the aged rat heart. T×4wk also significantly prolonged mitochondrial permeability transition pore opening times induced by reactive oxygen species in old cardiomyocytes. Our studies demonstrate that 4 wk of Tempol pretreatment restores anesthetic preconditioning and cardioprotection by CsA in the old rat and that this is associated with decreased oxidative stress and improved mitochondrial function. Our results point to a new protective strategy for the ischemic myocardium in the high-risk older population.

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