Cyclophilin D and myocardial ischemia-reperfusion injury: a fresh perspective.

Journal of Molecular and Cellular Cardiology 78 (2015) 80–89

Contents lists available at ScienceDirect

Journal of Molecular and Cellular Cardiology journal homepage: www.elsevier.com/locate/yjmcc

Review article

Cyclophilin D and myocardial ischemia–reperfusion injury: A fresh perspective Muhammad Rizwan Alam a, Delphine Baetz a, Michel Ovize a,b,⁎ a b

INSERM U1060, CarMeN Laboratory, Claude Bernard Lyon 1 University, F-69373 Lyon, France Hospices Civils de Lyon, Hôpital Louis Pradel, Service d'Explorations Fonctionnelles Cardiovasculaires & CIC de Lyon, F-69394 Lyon, France

a r t i c l e

i n f o

Article history: Received 20 July 2014 Received in revised form 23 September 2014 Accepted 25 September 2014 Available online 2 October 2014 Keywords: Ischemia–reperfusion Cyclophilin D Mitochondrial permeability transition pore Cell death Necrosis

a b s t r a c t Reperfusion is characterized by a deregulation of ion homeostasis and generation of reactive oxygen species that enhance the ischemia-related tissue damage culminating in cell death. The mitochondrial permeability transition pore (mPTP) has been established as an important mediator of ischemia–reperfusion (IR)-induced necrotic cell death. Although a handful of proteins have been proposed to contribute in mPTP induction, cyclophilin D (CypD) remains its only bona fide regulatory component. In this review we summarize existing knowledge on the involvement of CypD in mPTP formation in general and its relevance to cardiac IR injury in specific. Moreover, we provide insights of recent advancements on additional functions of CypD depending on its interaction partners and post-translational modifications. Finally we emphasize the therapeutic strategies targeting CypD in myocardial IR injury. This article is part of a Special Issue entitled "Mitochondria: From Basic Mitochondrial Biology to Cardiovascular Disease". © 2014 Published by Elsevier Ltd.

Contents 1. 2. 3. 4.

Introduction . . . . . . . . . . . . . . . . . . . . . IR-mediated cell death . . . . . . . . . . . . . . . . Mitochondrial permeability transition pore . . . . . . . Cyclophilin D . . . . . . . . . . . . . . . . . . . . . 4.1. Historical overview . . . . . . . . . . . . . . . 4.2. The contribution of CypD in mPTP . . . . . . . . 4.3. Association of CypD with classical mPTP . . . . . 4.4. Pi carrier as a putative mPTP structural component 4.5. CypD and F1F0 ATP synthase-dependent mPTP . . 4.6. CypD-p53 complex as a trigger of mPTP . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . .

81 81 81 82 82 82 82 83 83 83

Abbreviations: ANT, adenine nucleotide translocator; ATP, adenosine triphosphate; ATP5G, ATP synthase, H+ transporting, mitochondrial F0 complex, subunit C1 (subunit 9); BAK, BCL2antagonist/killer; BAX, BCL2-associated X protein; BCL-2, B cell lymphoma protein 2; C1QBP, complement 1q-binding protein; CGP37157, 7-Chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1benzothiazepin-2(3H)-one; CKMT1, creatine kinase mitochondrial 1; CsA, cyclosporin A; CSMDHs, calcium-sensitive matrix dehydrogenases; CypA, cyclophilin A; CypD, cyclophilin D; DnaJC15, DnaJ (Hsp40) homolog, subfamily C, member 15; EMRE, essential MCU regulator; ER, endoplasmic reticulum; ERK2, extracellular regulated kinase 2; GRP75, Glucose regulated protein 75; GSK3β, glycogen synthase kinase 3β; HK1/2, hexokinase 1/2; HSP60/90, heat shock protein 60/90; IMM, inner mitochondrial membrane; IP3, inositol 1, 4, 5 trisphosphate; IP3R1, inositol 1, 4, 5 trisphosphate receptor type 1; IR, ischemia reperfusion; LV, left ventricle; KO, Knockout; MAMs, mitochondria-associated membranes; MCU, mitochondrial calcium uniporter; MI, myocardial infarction;MICU1, mitochondrial calcium uptake 1;MLKL, mixedlineage kinase domain-like protein;mPTP, mitochondrialpermeability transition pore; MST1,mammalian sterile 20-like kinase 1; mΔΨ, mitochondrial membrane potential; NAD+, nicotinamide adenine dinucleotide oxidized; NADH, nicotinamide adenine dinucleotide reduced; NCLX, sodium calcium lithium exchanger; NIM811, N-methyl-4-isoleucine cyclosporine; OSCP, oligomycin-sensitivity conferring protein; PAGE, polyacrylamide gel electrophoresis; Pi, inorganic phosphate; PiC, mitochondrial phosphate carrier; PostC, post-conditioning; PPIase, peptidyl-prolyl cis-trans isomerase; PPIF, peptide-prolyl isomerase F; PreC, pre-conditioning; PT, mitochondrial permeability transition; PTMs, post-translational modifications; RIPK1, receptor-interacting protein kinase 1; RIPK3, receptor-interacting protein kinase 3; ROS, reactive oxygen species; SfA, sanglifehrin A; SERCA, sarco/endoplasmic reticulum Ca2 +-ATPase; siRNA, small interfering RNA; SIRT3, sirtuin 3; SNO, S-nitrosylation; STEMI, ST segment elevation myocardial infarction; STAT3, signal transducer and activator of transcription 3; TRAP1, tumor necrosis factor receptor-associated protein 1; TSPO, translocator protein; VDAC, voltage-dependent anion channel. ⁎ Corresponding author at: Inserm U1060 – CarMeN team 5 (Cardioprotection), 8 avenue Rockefeller, 69373 Lyon cedex 08, France. Tel.: +33 4 78 77 71 21; fax: +33 4 78 77 71 75. E-mail address: [email protected] (M. Ovize). URL: https://ihu-opera.com (M. Ovize).

http://dx.doi.org/10.1016/j.yjmcc.2014.09.026 0022-2828/© 2014 Published by Elsevier Ltd.

M.R. Alam et al. / Journal of Molecular and Cellular Cardiology 78 (2015) 80–89

4.7. 4.8. 4.9.

Other CypD binding proteins . . . . . . . . . . . . . . . . . Novel interacting partners of CypD . . . . . . . . . . . . . . Role of CypD in cell physiology . . . . . . . . . . . . . . . . 4.9.1. CypD in mitochondrial calcium efflux . . . . . . . . . 4.9.2. CypD in mitochondrial calcium uptake . . . . . . . . 4.9.3. CypD in metabolic homeostasis . . . . . . . . . . . . 4.9.4. CypD D in autophagy . . . . . . . . . . . . . . . . 4.9.5. Involvement of CypD in mitochondria–nucleus signaling 4.10. Regulation of CypD by post-translational modifications . . . . 4.11. CypD in myocardial IR injury and cardioprotection . . . . . . . Conflict of interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1. Introduction Myocardial infarction (MI) remains the most common debilitating disease and important cause of death in developed world [1,2]. Following coronary occlusion, deprivation of oxygen and nutrient metabolites is the primary cause of damage to the myocardium and its severity depends on the scale and duration of artery obstruction. Reoxygenation of hypoxic tissue, referred to as ischemia–reperfusion (IR), exacerbates injury experienced during the ischemic episode. Experimental evidence suggests that reperfusion per se contributes to up to half of the myocardial infarct size and it diminishes the beneficial effects of myocardial reflow [2,3]. For many years various pre- and post-conditioning (PreC and PostC) modalities are extensively being tested to improve usefulness of reperfusion therapy. Although ischemic PreC, a potent endogenous protective strategy, was first reported many decades ago [4], its utility in MI patients with an abrupt onset of disease in clinical settings undermines its implementation. Therefore, most modern approaches are focusing on the application of pharmacological or ischemic PostC maneuvers to reduce lethal outcomes of IR injury [3,5]. IR triggers many pro-death signaling pathways which converge on to the mitochondria [6,7]. Therefore mitochondrial dysfunction is considered to be one of the major mechanisms responsible for IR-induced cell death in ischemic heart. Reoxygenation of cardiomyocytes after an ischemic insult leads to accumulation of superfluous calcium and reactive oxygen species (ROS) in the mitochondrial matrix. It triggers mitochondrial permeability transition (PT) which is associated with the opening of the so-called mitochondrial permeability transition pore (mPTP). The subsequent swelling of mitochondria due to influx of water and ions leads to dissipation of mitochondrial membrane potential (mΔΨ), uncoupling of oxidative phosphorylation, loss of ATP and finally rupture of mitochondrial membranes, thus activating necrotic signaling cascades. Although mild PT can be recovered by autophagic degradation of damaged mitochondria, disseminated PT may lead to irreversible tissue/organ damage [7–10] 2. IR-mediated cell death In addition to their role in cellular metabolism and calcium homeostasis, mitochondria have also been established as major players in triggering cell death signaling cascades resulting in necrosis and/or apoptosis which contributes to pathogenesis of many diseases. Mitochondria harbor molecular machineries both for the execution of apoptosis and regulated necrosis in response to a variety of stimuli [6,11,12]. Although apoptosis has been reported to contribute to IR injury, mPTP-mediated necrosis remains a major therapeutic target. Necrosis, which has been generally regarded as a random accidental event causing a passive cell death, is now considered a well regulated process (at least in some context). While RIPK1–RIPK3-MLKL dependent programmed necrosis (necroptosis) is the most well characterized form of regulated necrosis, cyclophilin D (CypD)-mediated necrosis has

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

81

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . . . . . .

83 83 84 84 84 84 85 85 85 85 86 86 86

been studied extensively in context of IR injury [12–14]. Intriguingly, both of these pathways can also work side by side independent of each other as demonstrated by an augmentation of beneficial effects of CypD and RIPK3 silencing in a murine model of IR-mediated cell death [15]. However, this review will mainly focus on CypDdependent necrosis as comprehensive articles on other types of regulated necrosis are already published [13,14,16]. 3. Mitochondrial permeability transition pore The mPTP, a non-specific channel formed in the inner mitochondrial membrane (IMM), contributes to the pathogenesis of many diseases including (but not limited to) myocardial IR injury [17,18]. It is suggested as an equivalent of the electrophysiologically sought mitochondrial mega-channel that allows the passage of molecules of b1500 Da to pass through the IMM which is normally impermeable to most solutes [8,18]. A number of stress agents trigger formation of the mPTP making it a common cell death pathway [8]. Moreover, there is experimental evidence linking the mPTP both with necrotic and apoptotic cell deaths depending upon the energetic status of cells [19,20]. Nevertheless, necrosis is believed to be the major culprit in myocardial IR injury [12,21,22]. The mPTP has been extensively characterized in numerous cell models and remains an important therapeutic target in various diseases, particularly the lethal IR injury [10,22–24]. Although several proteins have been reported to contribute to formation and function of the mPTP, its exact molecular identity remains incompletely understood [18,22]. Prior to the investigation of mice lacking the adenine nucleotide translocator (ANT) and the voltage-dependent anion channel (VDAC), these proteins were the principal candidates for mPTP formation [8,25–27]. But studies in knockout (KO) models raised questions about their involvement in mPTP formation. Although a regulatory role of VDAC and ANT cannot be completely omitted in mPTP modulation [8,22], they are dispensable for its formation [17,28,29]. Correspondingly, creatine kinase mitochondrial 1 (CKMT1) and hexokinase 1 (HK1), as part of supramolecular complexes containing VDAC1 and ANT, were also documented to bear mPTP-like electrophysiological properties [22]. Since both CKMT1 and HK1 are involved in important metabolic reactions, they are proposed to have a more regulatory role in mPTP formation [22,27,30]. Largely based on pharmacological studies, the translocator protein (TSPO), a component of peripheral benzodiazepine receptor, has also been listed as a regulator of the mPTP [31,32]. But a recent report in mice with a conditional elimination of the TSPO gene has ruled out its involvement in mPTP induction [33]. Furthermore, experimental evidence suggests that the mitochondrial phosphate carrier (PiC) also contributes to mPTP activity which is generally based on its presence in the IMM and interaction with ANT1 and CypD [34, 35]. However, two new studies performed on mice genetically depleted of the PiC gene have challenged this idea [36,37]. Although the mPTP is generally thought to be an inner membrane phenomenon [38,39],

82


Fig. 1. A proposed model of the mPTP based on the existing data. ATP synthase F0 domain may form a core with ANT, PiC, CypD, CKMT1 and p53 as the peripheral regulatory components of a fundamental unit. GSK3-β and SIRT3 (not shown) may also indirectly contribute by modifying the phosphorylation and acetylation status of the either regulatory or core components. Although debated, outer membrane VDAC–HKII and BAK–BAX protein complexes may also have important contributions in mPTP formation in addition to their involvement in outer membrane permeabilization. Future studies should help us to demystify the critical role of c-subunit of ATP synthase in the formation of mysterious mPTP pore. Uniplex is the mitochondrial calcium uptake complex which is composed of MCU (Green), MICU1/2 (Orange) and EMRE (Purple).

pro-apoptotic BAX and BAK proteins responsible for permeabilization of the outer mitochondrial membrane (OMM) [40,41], have been additionally suggested to contribute to mPTP-dependent necrotic cell death (Fig. 1) [42]. Lately, also the ATP synthase has been proposed to play a role in mPTP formation fetching a lot of excitement in this field [43]. However, like other mPTP candidates, there are open questions (discussed in Section 4.5) which need to be answered before the ATP synthase can be firmly established as a structural/regulatory component of the mPTP. Regardless of all controversies in resolving the molecular enigma of mPTP, a general consensus exists on the role of CypD as a regulator of mPTP. Since the first report of a CypD KO mouse model [44,45], a plethora of studies have described its participation both in physiology and mPTP-dependent pathologies [23,46–48]. This review will focus on the role of CypD in cellular physiology based on its contribution to the mPTP and also on its function out of mPTP with implications in myocardial IR injury. 4. Cyclophilin D 4.1. Historical overview CypD belongs to a family of proteins which have been named as ‘cyclophilins’ due to their affinity to an immunosuppressant drug: cyclosporin A (CsA). Found both in prokaryotes and eukaryotes, cyclophilins are characterized by an evolutionarily conserved peptidyl-prolyl cis-trans isomerase (PPIase) activity [46]. First cyclophilin was discovered in 1984 as a cytosolic target of CsA [49]. Later it was observed that cyclophilin and PPIase are identical proteins and PPIase activity, which is inhibited by CsA, might be involved in immunosuppression [50,51]. The quest for existence of a mitochondrial cyclophilin isoform started when CsA was demonstrated to: (1) modulate mitochondrial calcium homeostasis and 2) inhibit calcium-induced permeabilization of the IMM [52–54]. The Halestrap laboratory was the first to provide evidence for a mitochondrial PPIase isoform [55]. These findings were later confirmed by two studies demonstrating purification and partial

sequencing of matrix PPIase from rat and bovine liver mitochondria; thus revealing the presence of a distinct mitochondrial cyclophilin isoform [55,56]. Later named as CypD, this mitochondrial PPIase is encoded by peptide-prolyl isomerase F (PPIF) gene in humans with a full length protein of 207 amino acids having a N85% homology to its rodent counterparts [47,57]. The mitochondrial targeting sequence of CypD is cleaved as a result of post-translational processing to form a mature protein of ~ 18 kDa which localizes to mitochondrial matrix [58]. However, a longer ~ 21 kDa uncleaved protein has also been proposed to exist in heart tissue which has recently caught attention due to the latest work by our laboratory (see Section 4.8) [47,59,60]. Although physiological role of CypD has not been established so far, it remains a thought-provoking target for scientists in biomedical research due to its potential involvement in mitochondria–dependent cell death pathways in cardiovascular, liver, kidney and brain pathologies along with its contribution to drug resistance in cancer [22]. Out of its involvement in mPTP regulation, CypD has also been recently proposed to bear some extra-mitochondrial activities [61]. Moreover, CypD KO mouse models, which are widely used for exploring the role of CypD in physiology and disease processes, have perturbations in their metabolism and calcium homeostasis which will also be a part of this discussion. It is worthwhile to emphasize that while using CypD KO mice as disease models one should not attribute data solely to mPTP modulation as CypD KO may also result in extra-mPTP yet unknown physiological alterations. 4.2. The contribution of CypD in mPTP Since the initial reports on existence of mitochondrial cyclophilin in late 1980s, a vast majority of studies have recognized the crucial role of CypD in mPTP regulation. Most of these data were based on pharmacological (CsA) or transient (siRNA) inhibition of CypD and a clear demonstration of its pathophysiological function was hampered until 2005 when three studies in KO mouse models confirmed its connection with the mPTP [44,45,62]. These discoveries instigated a scrutiny of many different cellular models including the heart, liver, kidney and brain both in vivo and in vitro to clarify exact CypD function in the mPTP. Since then a consensus has been established on the fundamental role of CypD in mPTP regulation. CypD modulates mPTP-dependent process by interacting with other proteins which has led to development of different models over the last two decades. 4.3. Association of CypD with classical mPTP The contact-site hypothesis of mPTP formation, which developed in the last two decades, was based on various studies suggesting the presence of VDAC and ANT in the OMM and IMM respectively as major mPTP components [18]. CypD binds to ANT and VDAC-ANT complexes and this association is enhanced by oxidation of distinct thiol species in ANT molecule [63,64]. Thus oxidative stress may increase mPTP activity by enhancing thiol oxidation-dependent formation of CypD-ANT complexes in the IMM [23,65,66]. Similarly calciuminduced binding of CypD to matrix face of ANT has also been proposed to bring a conformational change converting it into a non-specific channel [66]. The first model of mPTP which is mainly based on the structural and functional communication of VDAC, ANT and CypD was undermined by more robust studies in the genetically-manipulated mice [22]. The cells from KO mouse models of ANT and VDAC display robust mPTP activity, consequently weakening the critical role of VDAC and ANT as mPTP components [28,29]. Nevertheless, a regulatory function of ANT in mPTP formation could not be excluded due to the fact that more calcium is required to activate mPTP in ANT1/ANT2 KO cells [28]. Similarly the existence of two additional isoforms of ANT (ANT3 and ANT4), which were not manipulated in the above mentioned studies, may also contribute to mPTP formation. [28,67,68]. Although VDAC has been demonstrated to be indispensable for the mPTP,


components of the OMM are still known to contribute to its induction [42,69]. Remarkably and unlike ANT and VDAC, deletion of CypD in Ppif KO mice resulted in a marked desensitization of the mPTP to calcium and oxidative stress establishing it as a crucial mPTP component [44,45,62]. Nonetheless, although CypD null mitochondria are more resistant to calcium and ROS, they still display mPTP activity. Therefore one should be careful in interpretation of data obtained from experiments using pharmacological or genetic CypD inhibition, which only show desensitization but not complete blockage of mPTP [18]. Similarly, one has to acknowledge that the classical measurement of calcium retention capacity of isolated mitochondria to assess mPTP function may represent one (but not all) aspects of PT. 4.4. Pi carrier as a putative mPTP structural component In 2008, Halestrap laboratory proposed PiC as mPTP component based on its interaction with CypD in a CsA-sensitive fashion. They also demonstrated the binding of PiC with ANT and modulation of these interactions by mPTP-triggering and inhibiting agents [35]. However, like ANT and VDAC, its role as a core component of mPTP remained a matter of debate until very recently when two back-to-back studies in mice, with an inducible and cardiac specific ablation of PiC, revealed that PiC does not directly participate in mPTP formation [36,37]. Although results of two groups differ at the level of calcium-induced induction of mPTP in isolated mitochondria, they reached a similar final conclusion that mitochondria from PiC-ablated hearts still have the capability to form mPTP. However, Kwong et al. found that heart mitochondria lacking PiC required a considerably higher amount of calcium for mPTP opening as compared to their wild type counterparts. Moreover, MEFs from these mice exhibited a significantly attenuated necrotic cell death in response to ionomycin. Consistent with this data there was also a reduction in cardiac IR injury in KO mice suggesting PiC as a promising therapeutic target. [36]. Based on these data and also that of others (showing PiC interaction with ANT and CypD), it is tempting to speculate that PiC may contribute in modulation of mPTP without having a direct involvement in mPTP formation. 4.5. CypD and F1F0 ATP synthase-dependent mPTP CypD interacts with lateral stalk (Oligomycin-sensitivity conferring proteins (OSCP), b and d subunits) of ATP synthase in a CsA-sensitive fashion. This binding negatively regulates the catalytic activity of ATP synthase without impacting the assembly of ATP synthase as demonstrated in CypD KO mouse model [70]. Additionally, CypD ablation has been observed to increase matrix ATP levels with no influence on cytosolic fraction or ATP influx/efflux via ANT [71]. Interestingly, the recent demonstration of ATP synthase as a putative structural component of mPTP has revised classical model of the mPTP. Paolo Bernardi's group showed that dimers of ATP synthase produce calcium currents in reconstituted lipid bilayers with electrophysiological properties similar to that of the mPTP [43]. Another recent study by same group suggests that yeast F-ATP synthase dimers also form a calcium-dependent pore and this dimerization process is facilitated by e and g components of yeast multiprotein complex [72]. Although the mammalian ATP synthase shares a number of structural and functional characteristics with the mPTP [18,22], some recent studies disagree with this hypothesis. The formation of an active mPTP in ρ0 cells despite the existence of highly unstable ATP synthase dimers in this model [73,74] and a cytoprotective role of ATP synthase oligomers [75,76] argue against the dimer hypothesis. The c-subunit of ATP synthase which is a part of the so-called H+ transporting F0 domain has recently been suggested to be a part of the mPTP. A siRNA-mediated silencing approach demonstrated that transient suppression of c-subunit attenuates the calciumand ROS-induced mPTP formation [77]. In line with these and previous data [77,78], Alavian et al. recently reported that c-subunit may be a strong candidate for the structural component of mPTP. Using a

83

combination of electrophysiological and biochemical approaches, authors have demonstrated that calcium and CypD uncouple ATP synthase F1-component from the membrane-embedded F0-domain by expanding the c-subunit which leads to mPTP opening [79]. Nevertheless, these data still need to be validated in genetically-manipulated animal models before ATP synthase can be established as a major structural component of the mPTP. 4.6. CypD-p53 complex as a trigger of mPTP Moll and colleagues recently discovered that oxidative stress triggers the formation of an inducible CypD-p53 complex and this interaction promotes CypD-dependent mPTP opening and necrosis [80]. This study received a lot of attention and was followed by other reports proposing a crucial role of p53-CypD interaction in mPTP-dependent necrosis in different cell models [81–83]. Moreover, p53 has also been demonstrated to interact with OSCP subunit of ATP synthase. This association is suggested to modulate normal mitochondrial physiology and help tumor suppression in certain cell models [84]. Therefore, p53 may be proposed as a central hub in stress-induced apoptosis and necrosis instigated in mitochondria and may act as a novel therapeutic target for mPTP-dependent pathologies. Though the study by Moll's group is convincing and considerably important, some questions remain to be addressed for a better understanding of the relationship between CypD and p53 in mitochondria-dependent necrosis and to further elucidate its pathophysiological relevance [85]. These questions include: (1) The formation of mPTP in mitochondria lacking p53 and (2) the absence of p53 involvement in calcium-induced mPTP opening, which is major trigger for CypD-dependent mPTP induction. 4.7. Other CypD binding proteins In addition to the abovementioned extensively studied partners, CypD has also been demonstrated to interact with complement binding protein (C1QBP) and a recently described DnaJC15 protein, both of which contribute to mPTP induction [86,87]. Similarly, signal transducer and activator of transcription 3 (STAT3), has also been reported to bind with CypD and contribute to mPTP formation [88]. Amyloid β proteins which are a hallmark of Alzheimer's disease also participate in mPTP activation by interacting with CypD [89,90]. Furthermore, a large number of studies have highlighted the role of CypD in cancer resistance by inhibition of mPTP-induced apoptosis. Of note, the presence of an intricate chaperone network, including Hsp90, Hsp60 and TRAP1 in the mitochondria of cancer cells inhibits CypD which is then no longer available for mPTP-mediated cell death. Thus relieving CypD from the inhibitory action of these chaperones has been proposed as a promising target for selectively killing malignant cells [91]. In line with these findings, CypD has also been shown to inhibit apoptosis by CsA-sensitive binding with Bcl-2 and this mechanism has been suggested to be independent of its involvement in mPTP formation [92]. Keeping in view the regulation of CypD by post-translational modification, ERK2, GSK3β and SIRT3 have also been demonstrated to interact with CypD which are discussed in Section 4.10. 4.8. Novel interacting partners of CypD The central role of CypD in the regulation of mPTP by sensing high matrix calcium and ROS is well recognized. However, apart from its connection with the mPTP, it also interacts with additional proteins (Table 1) with implications in other pathologies such as cancer and metabolic diseases. Moreover, recent data from our lab have revealed some novel interacting partners of CypD highlighting its new role in cellular pathophysiology. Intriguingly and unexpectedly we have detected CypD in mitochondrial-associated membrane (MAM) fractions of the heart and liver. Using a combination of co-immunoprecipitation, proximity ligation assay and blue native PAGE we have identified that

84


Table 1 A summary of CypD interacting proteins and possible roles of these interactions. Protein(s)

Interaction place

Possible role of interaction

Reference

ANT–VDAC complex PiC ATP synthase p53 C1QBP GSK3-β/ERK2

IMM IMM IMM Matrix, IMM IMM IMS, Matrix

[63,64] [35] [70] [80] [86] [93,94]

SIRT3 STAT3 IP3R1–GRP75–VDAC1 complex Amyloid-beta protein Bcl2 HSP60, HSP90-TRAP1 MST1 DnaJC15

Matrix Matrix, ER, OMM, MAMs? IMM, Matrix IMM Matrix Matrix IMM

mPTP/necrosis mPTP/necrosis mPTP/necrosis mPTP/necrosis mPTP/necrosis mPTP/necrosis, inhibition of cells death mPTP/necrosis/apoptosis mPTP/necrosis ER-MITO cross talk mPTP, Alzheimer's disease Anti-apoptosis, cancer Anti-apoptosis, cancer mPTP/necrosis mPTP/apoptosis

[89,90] [92] [91,97] [98] [87]

[95,96] [88] [59,60]

CypD interacts with a complex composed of IP3R1, GRP75 and VDAC1 in mouse heart and liver [59,60]. Although we were not able to exclude any influence of CypD silencing on the endoplasmic reticulum (ER) calcium homeostasis, both genetic and pharmacological inhibition of CypD reduced IP3-mediated ER-mitochondrial calcium transfer [59]. The existence of CypD in MAMs and its interaction with the IP3RGRP75-VDAC1 complex raises two possibilities: (1) Based on the information that uncleaved CypD can be detected in the cytosol it is alluring to speculate on the presence of a small uncleaved CypD fraction which is retained in the cytosol and forms a complex with IP3R1-GRP75-VDAC1 and/or (2) it may be a part of a supercomplex which spans mitochondrial membranes via some unknown interacting partners. Further investigations should help us to answer these intriguing questions and better understand the pathophysiological relevance of CypD in MAMs. 4.9. Role of CypD in cell physiology Although CypD has been largely seen as a drug target for treating various mPTP-associated pathologies, its physiological function still remains debated. In the following sections we discuss the putative physiological role of CypD based on the current literature. 4.9.1. CypD in mitochondrial calcium efflux Various studies have demonstrated a transient reversible activation of the mPTP under physiological circumstances which might contribute to mitochondrial calcium efflux in certain conditions [99–101]. While most of these data are based on genetic/pharmacological inhibition of CypD, there are other studies contesting this model [102]. Two recent reports have also challenged the idea that CypD contributes to mPTP-mediated mitochondrial efflux [103,104]. Wei et al. provided evidence that CypD inhibition by CsA may actually inhibit mitochondrial Na+–Ca2 + exchanger (NCLX) resulting in mitochondrial calcium accumulation contradicting the participation of mPTP in Na+-independent mitochondrial calcium extrusion [103]. More recently De Marchi et al. investigated the role of mPTP in mitochondrial calcium efflux both by genetic (silencing of a different mPTP component, i.e. ATP5G) and pharmacological (CsA) approaches in HeLa cells [104]. Although the authors could not exclude an indirect involvement of the mPTP in mitochondrial calcium efflux (by modulation of mΔΨ), their data undoubtedly demonstrate that inhibition of the mPTP by CsA or siRNA against ATP5G do not alter the slope of mitochondrial calcium extrusion in conditions mimicking both physiology and disease. Previously, it has been suggested that the mPTP possesses a certain calcium threshold at which it probably works as a calcium release channel [105]. But De Marchi et al. revealed unaltered mitochondrial calcium extrusion kinetics upon mPTP inhibition, even when they overexpressed mitochondrial calcium

uniporter (MCU) and inhibited NCLX with CGP37157 for a maximal matrix calcium sequestration [104]. These findings do not support mPTP's contribution in physiological mitochondrial calcium efflux at least in HeLa cells. 4.9.2. CypD in mitochondrial calcium uptake Recent work from our laboratory has highlighted some novel aspects of CypD function in the modulation of ER–mitochondria calcium exchange in cardiac cells. We have found that CypD contributes to IP3-mediated calcium exchange between ER and mitochondria. Both transient and stable silencing of CypD abrogated mitochondrial calcium uptake upon stimulation of cells with histamine which triggered calcium transfer from ER to mitochondria via IP3R–GRP75–VDAC1 complex. Similarly, NIM811, a non-immunosuppressing inhibitor of CypD, also reduced IP3-mediated calcium exchange between the two organelles. Although the rate of caffeine-induced calcium release was not affected in CypD KO or NIM811 treated cells, we observed a clear reduction in maximal ER calcium release. Similarly, a reduction in action potentialstimulated cytosolic calcium transients and a relatively slower SERCA2 activity was demonstrated in CypD KO cardiomyocytes [59]. Therefore a decrease in ER calcium might be attributed to attenuated mitochondrial calcium uptake upon IP3R-mediated calcium release in CypD KO cells. But this question still needs to be answered by direct analysis of ER calcium homeostasis. Interestingly and consistent with our data, some other studies have revealed a similar impact of CypD inhibition on mitochondrial calcium uptake, in that CsA was able to inhibit mitochondrial calcium uptake in HeLa and adult skeletal muscle cells [106,107]. Montero et al. highlighted the fact that CsA is able to prevent MCU-mediated mitochondrial calcium uptake upon histamine stimulation while this outcome was not associated with any reduction of cytosolic calcium signals or modulation of the calcinerurin pathway [106]. However, there are many other reports describing an increase in mitochondrial calcium accumulation upon CypD inhibition [108]. These inconsistencies in existing literature may be attributed to the use of different CsA (or even other inhibitors) concentrations or due to various protocols which might result in variable cytosolic calcium levels during cell stimulation as indicated by our work and others [48,59,104–106]. Nevertheless, it is still possible to envisage a dual effect of CypD on ER-mitochondria calcium exchange along with its influence on mPTP induction, both of which actually contribute to mPTP-dependent cell damage and their inhibition is cytoprotective. Nevertheless, these novel findings still require further exploration to confirm whether CypD, with its presence in MAMs, is directly modulating the IP3R or it works via an indirect action on mitochondrial metabolism and ER calcium homeostasis. 4.9.3. CypD in metabolic homeostasis Increase in ATP synthase activity, substrate switching by genetic reprogramming, hyperglycemia and insulin resistance are the findings which have been previously described in CypD KO mice suggesting its role in metabolic homeostasis [48,70,109]. Recently CypD has been implicated in skeletal muscle insulin resistance by modulating the glucose uptake which was significantly improved in CypD KO animals. Surprisingly, it was not associated with any changes in liver and adipose tissue glucose homeostasis which are key organs contributing to glucose intolerance. Moreover, CypD KO also did not influence insulin signaling pathway as shown in this study [110]. These findings are in contrast to our recently published data, wherein a role of CypD in MAMs has been suggested to affect insulin resistance in liver accompanied by changes in insulin signaling pathway [60]. Interestingly, the activity of calcium-sensitive matrix dehydrogenases (CSMDHs) was not altered in skeletal muscle of CypD KO mice which is inconsistent with the study of Elrod et al. which proposed that increased matrix calcium due to mPTP inhibition may subsequently result in an enhanced activity of the CSMDHs in heart [48,110]. These tissue-specific


differences in mitochondrial metabolism may be a consequence of variable expression of CypD and/or that of its interacting partners which remain an open question for future studies. The recent discovery of acetylated mitochondrial proteome in CypD KO heart has triggered an interesting discussion about the role of lysine modification in heart pathophysiology [111]. The finding that CypD KO hearts have extensive hyperacetylation of many mitochondrial proteins, some of them are key enzymes involved in metabolic processes, goes in line with the previous studies reporting that CypD KO hearts have defects in various metabolic pathways [48,112]. As discussed previously, the increased lysine acetylation of the mitochondrial proteins in CypD KO hearts may be a consequence of reduced mitochondrial NAD+/NADH ratio which may cause a deficiency in SIRT3 activity. However, as described in this work, the protein acetylation profile from SIRT3 KO and CypD KO hearts has very little overlap suggesting the involvement of other, as yet unknown, mitochondrial acetylation modifying enzymes [111,113]. 4.9.4. CypD D in autophagy The injured mitochondria pose a major threat to cell survival and their removal by macroautophagy is the only known mechanism which can degrade these damaged organelles (known as mitophagy) [114]. Although CypD has a well-established role in mPTP-dependent cell death, many recent reports have emphasized its involvement in the regulation of macroautophagy [115,116]. Mitochondrial depolarization, which is the key activator of mitophagy, may be a result of CypDmediated mPTP induction in response to various stress stimuli. In line with this notion, genetic or pharmacological inhibition of CypD has been suggested to block the starvation-induced mitophagy [115]. Thus physiological function of CypD and/or mPTP may also encompass the modulation of autophagic machinery which maintains cellular and mitochondrial quality control. 4.9.5. Involvement of CypD in mitochondria–nucleus signaling The critical role of CypD in mitochondrial physiology has also been proposed to be accompanied by some extramitochondrial signaling events which may influence the gene expression and cell proliferation in tumor cells. Tavecchio et al. have revealed that CypD-ablated cells show increased proliferation, migration and invasion. The authors have attributed these changes to the modulation of nuclear expression of chemokines and activation of STAT3 which in turn enhances the expression of genes involved in cell proliferation and tissue invasion. Although a role of mitochondrial calcium homeostasis has already been suggested in mitochondrial retrograde signaling, how inhibition of CypD triggers nuclear gene expression, remains an open question [61]. 4.10. Regulation of CypD by post-translational modifications In addition to modulation of CypD by various proteins, posttranslational modifications (PTMs) also contribute to its regulation. However, until today only a few PTMs of CypD have been described which are listed in Table 2. Phosphorylation of CypD was first reported by Paolo Bernardi's group. Their work reveals a mitochondrial localized small fraction of GSK3β which interacts with CypD thus modulating its phosphorylation status on Ser/Thr residues. Moreover, this activity of GSK3β is dependent on the presence of ERK2 in the same mitochondrial fraction which co-immunoprecipitates with GSK3β/CypD complex. This

Table 2 Cyclophilin D post-translational modifications. Amino acids

PTMs

Proposed function

Reference

Ser/Thr Lys 166 Cys 203 Cys 203

Phosphorylation Acetylation Oxidation S-nitrosylation

mPTP activation Activation of mPTP, Anti-Apoptosis mPTP induction mPTP inhibition

[93] [95,96] [123] [124]

85

study suggests that ERK2 desensitizes mPTP by its action on CypD via GSK3β which contributes to resistance of malignant cells to apoptosis [93]. Although GSK3β translocation to mitochondria and its binding with CypD were already reported [94], this work has opened a new avenue for understanding the regulation of CypD by phosphorylation of its critical amino acid residues. During last few years SIRT3-mediated deacetylation of lysine residues has become a very intense area of research [117,118]. CypD has also been identified to contain a lysine residue (Lys166) which is modified by acetylation [95,96]. SIRT3-mediated deacetylation of CypD has been proposed to have opposite effects on necrosis and apoptosis. By inhibition of CypD binding to ANT, SIRT3 desensitizes mPTP, whereas by dissociation of HKII from OMM it may trigger BAK– BAX-dependent apoptosis [96,119]. Moreover, Shulga et al. have reported that ethanol increases the acetylation of CypD by reducing SIRT3 activity. This acetylated CypD has enhanced propensity to bind ANT1 which in turn increases the susceptibility of cells to mPTP opening [120]. All of the above mentioned data tend to disclose important contribution of CypD acetylation/deacetylation in mPTP modulation. Although SIRT3 KO mice have been reported to possess increased cardiac IR injury [121], a lack of mPTP sensitization in SIRT3 KO mitochondria questions the very role of CypD acetylation in mPTP formation [111]. Therefore, further studies are required to establish the participation of acetylated CypD in mPTP induction. Cysteine residues in protein molecules are susceptible to various PTMs including oxidation and S-nitrosylation (SNO) [122]. Cys203 of CypD has been demonstrated to be a target of both oxidation and SNO which are involved in mPTP induction and inhibition respectively [123,124]. Since SNO of cysteine residues has been suggested to protect them from irreversible oxidative modification [125], inhibition of Cys203 oxidation by prior SNO of CypD can be an interesting mPTP inhibition strategy [122]. 4.11. CypD in myocardial IR injury and cardioprotection Percutaneous coronary intervention and thrombolysis are primary therapeutic strategies in patients with MI. However, as mentioned previously, along with ischemia-induced damage, reperfusion itself triggers a sequence of events leading to mPTP opening and mitochondrial dysfunction which drastically undermine the beneficial impact of the abovementioned therapies. Therefore, protecting the heart from lethal IR injury during re-opening of the obstructed vessel remains a major challenge and there is an imperative demand for the development of therapeutic strategies to improve the beneficial effects of reperfusion [1]. Although a number of new therapies are being tested to reduce myocardial IR injury, the inhibition of CypD, long-known to attenuate the IR injury in various tissues including (but not limited to) the heart, brain, liver and kidney, remains an important viable therapeutic approach. CsA, which is a golden standard for the studies involving acute inhibition of CypD both in vivo and in vitro, was first demonstrated to inhibit the ischemia-induced liver damage in a canine model in late 1980s [126]. Nazareth et al. reported cardiomyocyte protection from substrate-free anoxia by CsA in 1991 suggesting that CsA treatment delays the cardiac injury probably at a late step of anoxia [127]. However, it was the Halestrap laboratory which convincingly demonstrated that CsA pretreatment protects the isolated heart from acute IR injury [128]. These studies were followed by a plethora of noteworthy contributions from various laboratories (summarized in 129), which facilitated us to reach the following generalizations about the role of CsA in the inhibition of myocardial IR injury: (1) CsA exerts its cardioprotective effect by blocking CypD-mediated mPTP opening in the early minutes of reperfusion [130,131], (2) CsA-mediated protection is independent of its action on calcinerurin as demonstrated by the use of tacrolimus (calcinerurin-inhibitor showing no protection) [129], and CsA analogs (Table 3) such as Sanglifehrin A (SfA) [132], Debio-0125 [133], NIM811 [134] and Cs29 [135], all of which provide a calcinerurin-

86


Table 3 Cyclophilin D inhibition strategies for cardioprotection in IR injury. Compound

Chemistry/origin

Potential effect

Reference

CsA

Cyclic undecapeptide originated from a fungus: Tolypocladium inflatum N-methyl-4-isoleucine cyclosporine A macrolide isolated from Streptomyces flaveolus Synthetic analog of CsA CsA conjugated with lipophilic triphenylphosphonium cation Synthetic oligonucleotides

Immunosuppression, mPTP inhibition mPTP inhibition Immunosuppression, mPTP inhibition More potent mPTP inhibition Preferential inhibition of CypD CypD knockdown

[49,129]

NIM811 Sanglifehrin A Debio-025 Mitochondria targeted CsA siRNA CypD

independent cardioprotection, (3) CsA and its non-immunosuppressive analogs are important experimental tools for investigating the function of CypD/mPTP and has a strong therapeutic potential in clinical settings [136,137], (4) As CsA and its non-immunosuppressive analogs (Table 3) inhibit all isoforms of cyclophilins [138], the contribution of CsA in cardioprotection may be a consequence of other mechanisms [139,140], and therefore results obtained with CsA and its analogs should not only be attributed to mPTP inhibition, (5) There is need to develop novel and CypD specific therapeutic strategies [141,142] and (6) Although chronic inhibition of CypD by CsA has been shown to cause metabolic reprogramming and worsening of pressure-induced heart failure [48], its acute inhibition to attenuate lethal IR injury holds a great promise for reducing myocardial infarct size in humans [3,136]. The data on CsA-mediated CypD inhibition in mPTP desensitization and cardioprotection was greatly strengthened by genetic studies in 2005 demonstrating that CypD KO mice are resistant to calcium and ROS-mediated mPTP formation [44,45,62]. Likewise, mice overexpressing CypD in the heart demonstrated swollen mitochondria making them more vulnerable to cell death [44]. Based on all these elegant reports and many others as well, CypD has reached a stage where its inhibitors are actively being tested both in animal models and MI patients ((1), Phase III Trial: NCT01502774). However, following aspects are worthwhile to be considered: (1) Formation of the mPTP is still observed in mitochondria devoid of CypD [62], therefore there is a need to completely elucidate the molecular nature of this nonselective pore for precise therapeutic targeting, (2) CypD-mediated mPTP formation is not the only trigger for IR-induced necrosis and mPTP-independent necrotic pathways also contribute to damage [15], which may also be targeted in addition to mPTP-mediated necrosis, (3) As with CsA, long term genetic depletion of CypD may result in loss of compensatory cardiac hypertrophy. Nevertheless, as mentioned previously, acute inhibition of CypD in myocardial IR injury remains a practical target for reducing infarct size and for improving cardiac functions. Although the cardioprotective effects of CypD inhibition in humans were already demonstrated [143,144], our group was the first to report a ground-breaking proof-of-concept clinical study in a small group of ST segment elevation myocardial infarction (STEMI) patients. Intravenous injection of a single dose of CsA just prior to reperfusion considerably reduced the blood levels of creatine kinase and troponin I as compared to placebo group. Remarkably, CsA treatment in STEMI patients was also able to decrease the infarct size as analyzed by cardiac magnetic resonance imaging. Interestingly, we did not observe any adverse effects of CsA treatment in these patients which is against all odds of chronic CsA treatment, providing a strong evidence for a safe and potential clinical therapy by only using a single dose of CsA to minimize myocardial IR injury [136]. As CsA also inhibits calcinerurin by binding with CypA, this complex can have detrimental influence on post-MI compensatory myocardial hypertrophy [47,129,142]. To address this issue we examined the left ventricular (LV) remodeling and function by cardiac magnetic resonance imaging at 5 days and 6 months in 2 groups of STEMI patients (controls vs CsA treated) selected from the aforementioned study. Interestingly, we observed a persistent reduction in infarct size in CsA treated group along with a reduced end-diastolic and end-systolic volumes after 6 months. Likewise, there was no alteration

[134,146,147] [132,148] [135] [149] [141]

in overall LV mass and wall thickness in non-infarcted myocardium in the CsA-treated compared to the control group. Thus, CsA used at the time of reperfusion in STEMI patients persistently reduced infarct size without having a harmful impact on LV remodeling [145]. However, since this data only represents a small group of patients, we are currently working on a large multicenter phase III clinical trial (ClinicalTrials.gov Identifier: NCT01502774l) to determine whether or not CsA can definitely improve the clinical outcome in STEMI patients. Nevertheless, there is still a need to find CypD-specific inhibitors along with further exploration of the mPTP for development of more efficient therapeutic strategies. In addition, modulation of s-nitrosylation, phosphorylation and acetylation of CypD also requires further investigation which may substantiate the search for development of novel therapeutic drugs. Conflict of interest None. Acknowledgments We would like to thank Lukas N. Groschner (University of Oxford, UK) and Dr. Salma Malik (HCL, Lyon) for critically reading the manuscript and for providing valuable suggestions. References [1] Hausenloy DJ, Yellon DM. Myocardial ischemia–reperfusion injury: a neglected therapeutic target. J Clin Invest 2013;123(1):92–100. [2] Yellon DM, Hausenloy DJ. Myocardial reperfusion injury. N Engl J Med 2007; 357(11):1121–35. [3] Ovize M, Thibault H, Przyklenk K. Myocardial conditioning: opportunities for clinical translation. Circ Res 2013;113(4):439–50. [4] Murry CE, Jennings RB, Reimer KA. Preconditioning with ischemia: a delay of lethal cell injury in ischemic myocardium. Circulation 1986;74(5):1124–36. [5] Tomai F, Crea F, Chiariello L, Gioffrè PA. Ischemic preconditioning in humans: models, mediators, and clinical relevance. Circulation 1999;100(5):559–63. [6] Galluzzi L, Kepp O, Kroemer G. Mitochondria: master regulators of danger signalling. Nat Rev Mol Cell Biol 2012;13(12):780–8. [7] Walters AM, Porter GA, Brookes PS. Mitochondria as a drug target in ischemic heart disease and cardiomyopathy. Circ Res 2012;111(9):1222–36. [8] Miura T, Tanno M. The mPTP and its regulatory proteins: final common targets of signalling pathways for protection against necrosis. Cardiovasc Res 2012;94(2): 181–9. [9] Juhaszova M, Zorov DB, Yaniv Y, Nuss HB, Wang S, Sollott SJ. Role of glycogen synthase kinase-3beta in cardioprotection. Circ Res 2009;104(11):1240–52. [10] Di Lisa F, Bernardi P. Mitochondria and ischemia–reperfusion injury of the heart: fixing a hole. Cardiovasc Res 2006;70(2):191–9. [11] Rizzuto R, De Stefani D, Raffaello A, Mammucari C. Mitochondria as sensors and regulators of calcium signalling. Nat Rev Mol Cell Biol 2012;13(9):566–78. [12] Kung G, Konstantinidis K, Kitsis RN. Programmed necrosis, not apoptosis, in the heart. Circ Res 2011;108(8):1017–36. [13] Vanden Berghe T, Linkermann A, Jouan-Lanhouet S, Walczak H, Vandenabeele P. Regulated necrosis: the expanding network of non-apoptotic cell death pathways. Nat Rev Mol Cell Biol 2014;15(2):135–47. [14] Linkermann A, Green DR. Necroptosis. N Engl J Med 2014;370(5):455–65. [15] Linkermann A, Bräsen JH, Darding M, Jin MK, Sanz AB, Heller JO, et al. Two independent pathways of regulated necrosis mediate ischemia–reperfusion injury. Proc Natl Acad Sci U S A 2013;110(29):12024–9. [16] Galluzzi L, Kepp O, Krautwald S, Kroemer G, Linkermann A. Molecular mechanisms of regulated necrosis. Semin Cell Dev Biol 2014. http://dx.doi.org/10.1016/j. semcdb.2014.02.006 [in press]. [17] Baines CP. The mitochondrial permeability transition pore and ischemia–reperfusion injury. Basic Res Cardiol 2009;104(2):181–8.

M.R. Alam et al. / Journal of Molecular and Cellular Cardiology 78 (2015) 80–89 [18] Bernardi P. The mitochondrial permeability transition pore: a mystery solved? Front Physiol 2013;4:95. [19] Leist M, Single B, Castoldi AF, Kühnle S, Nicotera P. Intracellular adenosine triphosphate (ATP) concentration: a switch in the decision between apoptosis and necrosis. J Exp Med 1997;185(8):1481–6. [20] Kinnally KW, Peixoto PM, Ryu SY, Dejean LM. Is mPTP the gatekeeper for necrosis, apoptosis, or both? Biochim Biophys Acta 2011;1813(4):616–22. [21] McCully JD, Wakiyama H, Hsieh YJ, Jones M, Levitsky S. Differential contribution of necrosis and apoptosis in myocardial ischemia–reperfusion injury. Am J Physiol Heart Circ Physiol 2004;286(5):H1923–35. [22] Bonora M, Wieckowski MR, Chinopoulos C, Kepp O, Kroemer G, Galluzzi L, et al. Molecular mechanisms of cell death: central implication of ATP synthase in mitochondrial permeability transition. Oncogene 2014. http://dx.doi.org/10.1038/ onc.2014.96. [23] Javadov S, Kuznetsov A. Mitochondrial permeability transition and cell death: the role of cyclophilin d. Front Physiol 2013;4:76. [24] Gomez L, Li B, Mewton N, Sanchez I, Piot C, Elbaz M, et al. Inhibition of mitochondrial permeability transition pore opening: translation to patients. Cardiovasc Res 2009; 83(2):226–33. [25] Szabó I, De Pinto V, Zoratti M. The mitochondrial permeability transition pore may comprise VDAC molecules. II. The electrophysiological properties of VDAC are compatible with those of the mitochondrial megachannel. FEBS Lett 1993; 330(2):206–10. [26] Szabó I, Zoratti M. The mitochondrial permeability transition pore may comprise VDAC molecules. I. Binary structure and voltage dependence of the pore. FEBS Lett 1993;330(2):201–5. [27] Beutner G, Rück A, Riede B, Brdiczka D. Complexes between porin, hexokinase, mitochondrial creatine kinase and adenylate translocator display properties of the permeability transition pore. Implication for regulation of permeability transition by the kinases. Biochim Biophys Acta 1998;1368(1):7–18. [28] Kokoszka JE, Waymire KG, Levy SE, Sligh JE, Cai J, Jones DP, et al. The ADP/ATP translocator is not essential for the mitochondrial permeability transition pore. Nature 2004;427(6973):461–5. [29] Baines CP, Kaiser RA, Sheiko T, Craigen WJ, Molkentin JD. Voltage-dependent anion channels are dispensable for mitochondrial-dependent cell death. Nat Cell Biol 2007;9(5):550–5. [30] Datler C, Pazarentzos E, Mahul-Mellier AL, Chaisaklert W, Hwang MS, Osborne F, et al. CKMT1 regulates the mitochondrial permeability transition pore in a process that provides evidence for alternative forms of the complex. J Cell Sci 2014; 127(Pt 8):1816–28. [31] Veenman L, Papadopoulos V, Gavish M. Channel-like functions of the 18-kDa translocator protein (TSPO): regulation of apoptosis and steroidogenesis as part of the host-defense response. Curr Pharm Des 2007;13(23):2385–405. [32] Qi X, Xu J, Wang F, Xiao J. Translocator protein (18 kDa): a promising therapeutic target and diagnostic tool for cardiovascular diseases. Oxid Med Cell Longev 2012;2012:162934. [33] Sileikytė J, Blachly-Dyson E, Sewell R, Carpi A, Menabò R, Di Lisa F, et al. Regulation of the mitochondrial permeability transition pore by the outer membrane does not involve the peripheral benzodiazepine receptor (translocator protein of 18 kDa (TSPO)). J Biol Chem 2014;289(20):13769–81. [34] Varanyuwatana P, Halestrap AP. The roles of phosphate and the phosphate carrier in the mitochondrial permeability transition pore. Mitochondrion 2012;12(1): 120–5. [35] Leung AWC, Varanyuwatana P, Halestrap AP. The mitochondrial phosphate carrier interacts with cyclophilin D and may play a key role in the permeability transition. J Biol Chem 2008;283(39):26312–23. [36] Kwong JQ, Davis J, Baines CP, Sargent MA, Karch J, Wang X, et al. Genetic deletion of the mitochondrial phosphate carrier desensitizes the mitochondrial permeability transition pore and causes cardiomyopathy. Cell Death Differ 2014;21(8):1209–17. [37] Gutiérrez-Aguilar M, Douglas DL, Gibson AK, Domeier TL, Molkentin JD, Baines CP. Genetic manipulation of the cardiac mitochondrial phosphate carrier does not affect permeability transition. J Mol Cell Cardiol 2014;72:316–25. [38] Vianello A, Casolo V, Petrussa E, Peresson C, Patui S, Bertolini A, et al. The mitochondrial permeability transition pore (PTP) — an example of multiple molecular exaptation? Biochim Biophys Acta 2012;1817(11):2072–86. [39] Sileikyte J, Petronilli V, Zulian A, Dabbeni-Sala F, Tognon G, Nikolov P, et al. Regulation of the inner membrane mitochondrial permeability transition by the outer membrane translocator protein (peripheral benzodiazepine receptor). J Biol Chem 2011;286(2):1046–53. [40] Westphal D, Kluck RM, Dewson G. Building blocks of the apoptotic pore: how Bax and Bak are activated and oligomerize during apoptosis. Cell Death Differ 2014; 21(2):196–205. [41] Juin P, Geneste O, Gautier F, Depil S, Campone M. Decoding and unlocking the BCL-2 dependency of cancer cells. Nat Rev Cancer 2013;13(7):455–65. [42] Karch J, Kwong JQ, Burr AR, Sargent MA, Elrod JW, Peixoto PM, et al. Bax and Bak function as the outer membrane component of the mitochondrial permeability pore in regulating necrotic cell death in mice. eLife 2013;2:e00772. [43] Giorgio V, von Stockum S, Antoniel M, Fabbro A, Fogolari F, Forte M, et al. Dimers of mitochondrial ATP synthase form the permeability transition pore. Proc Natl Acad Sci U S A 2013;110(15):5887–92. [44] Baines CP, Kaiser RA, Purcell NH, Blair NS, Osinska H, Hambleton MA, et al. Loss of cyclophilin D reveals a critical role for mitochondrial permeability transition in cell death. Nature 2005;434(7033):658–62. [45] Nakagawa T, Shimizu S, Watanabe T, Yamaguchi O, Otsu K, Yamagata H, et al. Cyclophilin D-dependent mitochondrial permeability transition regulates some necrotic but not apoptotic cell death. Nature 2005;434(7033):652–8.

87

[46] Giorgio V, Soriano M, Basso E, Bisetto E, Lippe G, Forte M, et al. Cyclophilin D in mitochondrial pathophysiology. Biochim Biophys Acta 2010;1797(6–7): 1113–8. [47] Elrod J, Molkentin J. Physiologic functions of cyclophilin D and the mitochondrial permeability transition pore. Circ J 2013;77(5):1111–22. [48] Elrod JW, Wong R, Mishra S, Vagnozzi RJ, Sakthievel B, Goonasekera SA, et al. Cyclophilin D controls mitochondrial pore-dependent Ca(2+) exchange, metabolic flexibility, and propensity for heart failure in mice. J Clin Invest 2010;120(10): 3680–7. [49] Handschumacher RE, Harding MW, Rice J, Drugge RJ, Speicher DW. Cyclophilin: a specific cytosolic binding protein for cyclosporin A. Science 1984;226(4674): 544–7. [50] Fischer G, Wittmann-Liebold B, Lang K, Kiefhaber T, Schmid FX. Cyclophilin and peptidyl-prolyl cis-trans isomerase are probably identical proteins. Nature 1989; 337(6206):476–8. [51] Takahashi N, Hayano T, Suzuki M. Peptidyl-prolyl cis-trans isomerase is the cyclosporin A-binding protein cyclophilin. Nature 1989;337(6206):473–5. [52] Fournier N, Ducet G, Crevat A. Action of cyclosporine on mitochondrial calcium fluxes. J Bioenerg Biomembr 1987;19(3):297–303. [53] Broekemeier KM, Pfeiffer DR. Cyclosporin A-sensitive and insensitive mechanisms produce the permeability transition in mitochondria. Biochem Biophys Res Commun 1989;163(1):561–6. [54] Broekemeier KM, Dempsey ME, Pfeiffer DR. Cyclosporin A is a potent inhibitor of the inner membrane permeability transition in liver mitochondria. J Biol Chem 1989;264(14):7826–30. [55] Connern CP, Halestrap AP. Purification and N-terminal sequencing of peptidylprolyl cis-trans-isomerase from rat liver mitochondrial matrix reveals the existence of a distinct mitochondrial cyclophilin. Biochem J 1992;284(Pt 2):381–5. [56] Inoue T, Yoshida Y, Isaka Y, Tagawa K. Isolation of mitochondrial cyclophilin from bovine heart. Biochem Biophys Res Commun 1993;190(3):857–63. [57] Bowles K, Zintz C, Abraham S, Brandon L, Bowles N, Towbin J. Genomic characterization of the human peptidyl-prolyl-cis-trans-isomerase, mitochondrial precursor gene: assessment of its role in familial dilated cardiomyopathy. Hum Genet 1999;105(6):582–6. [58] Johnson N, Khan A, Virji S, Ward J, Crompton M. Import and processing of heart mitochondrial cyclophilin D. Eur J Biochem 1999;263(2):353–9. [59] Paillard M, Tubbs E, Thiebaut PA, Gomez L, Fauconnier J, Da Silva CC, et al. Depressing mitochondria–reticulum interactions protects cardiomyocytes from lethal hypoxia–reoxygenation injury. Circulation 2013;128(14):1555–65. [60] Tubbs E, Theurey P, Vial G, Bendridi N, Bravard A, Chauvin MA, et al. Mitochondriaassociated endoplasmic reticulum membrane (MAM) integrity is required for insulin signaling and is implicated in hepatic insulin resistance. Diabetes 2014; 63(10):3279–94. [61] Tavecchio M, Lisanti S, Lam A, Ghosh JC, Martin NM, O'Connell M, et al. Cyclophilin D extramitochondrial signaling controls cell cycle progression and chemokinedirected cell motility. J Biol Chem 2013;288(8):5553–61. [62] Basso E, Fante L, Fowlkes J, Petronilli V, Forte MA, Bernardi P. Properties of the permeability transition pore in mitochondria devoid of cyclophilin D. J Biol Chem 2005;280(19):18558–61. [63] Crompton M, Virji S, Ward JM. Cyclophilin-D binds strongly to complexes of the voltage-dependent anion channel and the adenine nucleotide translocase to form the permeability transition pore. Eur J Biochem 1998;258(2):729–35. [64] Woodfield K, Rück A, Brdiczka D, Halestrap AP. Direct demonstration of a specific interaction between cyclophilin-D and the adenine nucleotide translocase confirms their role in the mitochondrial permeability transition. Biochem J 1998; 336(Pt 2):287–90. [65] McStay GP, Clarke SJ, Halestrap AP. Role of critical thiol groups on the matrix surface of the adenine nucleotide translocase in the mechanism of the mitochondrial permeability transition pore. Biochem J 2002;367(Pt 2):541–8. [66] Halestrap AP, Brenner C. The adenine nucleotide translocase: a central component of the mitochondrial permeability transition pore and key player in cell death. Curr Med Chem 2003;10(16):1507–25. [67] Dolce V, Scarcia P, Iacopetta D, Palmieri F. A fourth ADP/ATP carrier isoform in man: identification, bacterial expression, functional characterization and tissue distribution. FEBS Lett 2005;579(3):633–7. [68] Zamora M, Granell M, Mampel T, Viñas O. Adenine nucleotide translocase 3 (ANT3) overexpression induces apoptosis in cultured cells. FEBS Lett 2004;563(1–3): 155–60. [69] Roy SS, Madesh M, Davies E, Antonsson B, Danial N, Hajnóczky G. Bad targets the permeability transition pore independent of Bax or Bak to switch between Ca2+-dependent cell survival and death. Mol Cell 2009;33(3):377–88. [70] Giorgio V, Bisetto E, Soriano ME, Dabbeni-Sala F, Basso E, Petronilli V, et al. Cyclophilin D modulates mitochondrial F0F1-ATP synthase by interacting with the lateral stalk of the complex. J Biol Chem 2009;284(49):33982–8. [71] Chinopoulos C, Konràd C, Kiss G, Metelkin E, Töröcsik B, Zhang SF, et al. Modulation of F0F1-ATP synthase activity by cyclophilin D regulates matrix adenine nucleotide levels. FEBS J 2011;278(7):1112–25. [72] Carraro M, Giorgio V, Sileikytė J, Sartori G, Forte M, Lippe G, et al. Channel formation by yeast F-ATP synthase and the role of dimerization in the mitochondrial permeability transition. J Biol Chem 2014;289(23):15980–5. [73] Masgras I, Rasola A, Bernardi P. Induction of the permeability transition pore in cells depleted of mitochondrial DNA. Biochim Biophys Acta 2012;1817(10): 1860–6. [74] Wittig I, Meyer B, Heide H, Steger M, Bleier L, Wumaier Z, et al. Assembly and oligomerization of human ATP synthase lacking mitochondrial subunits a and A6L. Biochim Biophys Acta 2010;1797(6–7):1004–11.

88


[75] Daum B, Walter A, Horst A, Osiewacz HD, Kühlbrandt W. Age-dependent dissociation of ATP synthase dimers and loss of inner-membrane cristae in mitochondria. Proc Natl Acad Sci U S A 2013;110(38):15301–6. [76] Campanella M, Casswell E, Chong S, Farah Z, Wieckowski MR, Abramov AY, et al. Regulation of mitochondrial structure and function by the F1Fo-ATPase inhibitor protein, IF1. Cell Metab 2008;8(1):13–25. [77] Greie JC, Heitkamp T, Altendorf K. The transmembrane domain of subunit b of the Escherichia coli F1F(O) ATP synthase is sufficient for H(+)-translocating activity together with subunits a and c. Eur J Biochem 2004;271(14):3036–42. [78] McGeoch JE, Palmer DN. Ion pores made of mitochondrial ATP synthase subunit c in the neuronal plasma membrane and Batten disease. Mol Genet Metab 1999; 66(4):387–92. [79] Alavian KN, Beutner G, Lazrove E, Sacchetti S, Park HA, Licznerski P, et al. An uncoupling channel within the c-subunit ring of the F1FO ATP synthase is the mitochondrial permeability transition pore. Proc Natl Acad Sci U S A 2014; 111(29):10580–5. [80] Vaseva AV, Marchenko ND, Ji K, Tsirka SE, Holzmann S, Moll UM. p53 opens the mitochondrial permeability transition pore to trigger necrosis. Cell 2012;149(7): 1536–48. [81] Zhao LP, Ji C, Lu PH, Li C, Xu B, Gao H. Oxygen glucose deprivation (OGD)/ re-oxygenation-induced in vitro neuronal cell death involves mitochondrial cyclophilin-D/P53 signaling axis. Neurochem Res 2013;38(4):705–13. [82] Chen B, Xu M, Zhang H, Wang JX, Zheng P, Gong L, et al. Cisplatin-induced non-apoptotic death of pancreatic cancer cells requires mitochondrial cyclophilin-D-p53 signaling. Biochem Biophys Res Commun 2013;437(4):526–31. [83] Zhen YF, Wang GD, Zhu LQ, Tan SP, Zhang FY, Zhou XZ, et al. P53 dependent mitochondrial permeability transition pore opening is required for dexamethasoneinduced death of osteoblasts. J Cell Physiol 2014;229(10):1475–83. [84] Bergeaud M, Mathieu L, Guillaume A, Moll UM, Mignotte B, Le Floch N, et al. Mitochondrial p53 mediates a transcription-independent regulation of cell respiration and interacts with the mitochondrial F F0-ATP synthase. Cell Cycle 2013;12(17):2781–93. [85] Karch J, Molkentin JD. Is p53 the long-sought molecular trigger for cyclophilin D-regulated mitochondrial permeability transition pore formation and necrosis? Circ Res 2012;111(10):1258–60. [86] McGee AM, Baines CP. Complement 1q-binding protein inhibits the mitochondrial permeability transition pore and protects against oxidative stress-induced death. Biochem J 2011;433(1):119–25. [87] Sinha D, D'Silva P. Chaperoning mitochondrial permeability transition: regulation of transition pore complex by a J-protein, DnaJC15. Cell Death Dis 2014;5:e1101. [88] Boengler K, Hilfiker-Kleiner D, Heusch G, Schulz R. Inhibition of permeability transition pore opening by mitochondrial STAT3 and its role in myocardial ischemia/reperfusion. Basic Res Cardiol 2010;105(6):771–85. [89] Pagani L, Eckert A. Amyloid-beta interaction with mitochondria. Int J Alzheimers Dis 2011;2011:925050. [90] Du H, Guo L, Fang F, Chen D, Sosunov AA, McKhann GM, et al. Cyclophilin D deficiency attenuates mitochondrial and neuronal perturbation and ameliorates learning and memory in Alzheimer's disease. Nat Med 2008;14(10):1097–105. [91] Kang BH, Plescia J, Dohi T, Rosa J, Doxsey SJ, Altieri DC. Regulation of tumor cell mitochondrial homeostasis by an organelle-specific Hsp90 chaperone network. Cell 2007;131(2):257–70. [92] Eliseev RA, Malecki J, Lester T, Zhang Y, Humphrey J, Gunter TE. Cyclophilin D interacts with Bcl2 and exerts an anti-apoptotic effect. J Biol Chem 2009;284(15):9692–9. [93] Rasola A, Sciacovelli M, Chiara F, Pantic B, Brusilow WS, Bernardi P. Activation of mitochondrial ERK protects cancer cells from death through inhibition of the permeability transition. Proc Natl Acad Sci U S A 2010;107(2):726–31. [94] Xi J, Wang H, Mueller RA, Norfleet EA, Xu Z. Mechanism for resveratrol-induced cardioprotection against reperfusion injury involves glycogen synthase kinase 3beta and mitochondrial permeability transition pore. Eur J Pharmacol 2009; 604(1–3):111–6. [95] Shulga N, Wilson-Smith R, Pastorino JG. Sirtuin-3 deacetylation of cyclophilin D induces dissociation of hexokinase II from the mitochondria. J Cell Sci 2010; 123(Pt 6):894–902. [96] Hafner AV, Dai J, Gomes AP, Xiao CY, Palmeira CM, Rosenzweig A, et al. Regulation of the mPTP by SIRT3-mediated deacetylation of CypD at lysine 166 suppresses age-related cardiac hypertrophy. Aging 2010;2(12):914–23. [97] Ghosh JC, Siegelin MD, Dohi T, Altieri DC. Heat shock protein 60 regulation of the mitochondrial permeability transition pore in tumor cells. Cancer Res 2010; 70(22):8988–93. [98] Chen SH, Li DL, Yang F, Wu Z, Zhao YY, Jiang Y. Gemcitabine-induced pancreatic cancer cell death is associated with MST1/cyclophilin D mitochondrial complexation. Biochimie 2014;103:71–9. [99] Bernardi P, von Stockum S. The permeability transition pore as a Ca(2+) release channel: new answers to an old question. Cell Calcium 2012;52(1):22–7. [100] Petronilli V, Miotto G, Canton M, Brini M, Colonna R, Bernardi P, et al. Transient and long-lasting openings of the mitochondrial permeability transition pore can be monitored directly in intact cells by changes in mitochondrial calcein fluorescence. Biophys J 1999;76(2):725–34. [101] Hüser J, Blatter LA. Fluctuations in mitochondrial membrane potential caused by repetitive gating of the permeability transition pore. Biochem J 1999;343(Pt 2):311–7. [102] Eriksson O, Pollesello P, Geimonen E. Regulation of total mitochondrial Ca2+ in perfused liver is independent of the permeability transition pore. Am J Physiol 1999;276(6 Pt 1):C1297–302. [103] Wei AC, Liu T, Cortassa S, Winslow RL, O'Rourke B. Mitochondrial Ca2+ influx and efflux rates in guinea pig cardiac mitochondria: low and high affinity effects of cyclosporine A. Biochim Biophys Acta 2011;1813(7):1373–81.

[104] De Marchi E, Bonora M, Giorgi C, Pinton P. The mitochondrial permeability transition pore is a dispensable element for mitochondrial calcium efflux. Cell Calcium 2014;56(1):1–3. [105] Barsukova A, Komarov A, Hajnóczky G, Bernardi P, Bourdette D, Forte M. Activation of the mitochondrial permeability transition pore modulates Ca2+ responses to physiological stimuli in adult neurons. Eur J Neurosci 2011;33(5):831–42. [106] Montero M, Lobatón CD, Gutierrez-Fernández S, Moreno A, Alvarez J. Calcineurinindependent inhibition of mitochondrial Ca2 + uptake by cyclosporin A. Br J Pharmacol 2004;141(2):263–8. [107] Aydin J, Andersson DC, Hänninen SL, Wredenberg A, Tavi P, Park CB, et al. Increased mitochondrial Ca2+ and decreased sarcoplasmic reticulum Ca2+ in mitochondrial myopathy. Hum Mol Genet 2009;18(2):278–88. [108] Elrod JW, Molkentin JD. Physiologic functions of cyclophilin D and the mitochondrial permeability transition pore. Circ J 2013;77(5):1111–22. [109] Devalaraja-Narashimha K, Diener AM, Padanilam BJ. Cyclophilin D deficiency prevents diet-induced obesity in mice. FEBS Lett 2011;585(4):677–82. [110] Taddeo EP, Laker RC, Breen DS, Akhtar YN, Kenwood BM, Liao JA, et al. Opening of the mitochondrial permeability transition pore links mitochondrial dysfunction to insulin resistance in skeletal muscle. Mol Metab 2014;3(2):124–34. [111] Nguyen TTM, Wong R, Menazza S, Sun J, Chen Y, Wang G, et al. Cyclophilin D modulates mitochondrial acetylome. Circ Res 2013;113(12):1308–19. [112] Menazza S, Wong R, Nguyen T, Wang G, Gucek M, Murphy E. CypD(−/−) hearts have altered levels of proteins involved in Krebs cycle, branch chain amino acid degradation and pyruvate metabolism. J Mol Cell Cardiol 2013;56:81–90. [113] Lam MPY, Lau E, Liem DA, Ping P. Cyclophilin d and acetylation: a new link in cardiac signaling. Circ Res 2013;113(12):1268–9. [114] Dutta D, Calvani R, Bernabei R, Leeuwenburgh C, Marzetti E. Contribution of impaired mitochondrial autophagy to cardiac aging: mechanisms and therapeutic opportunities. Circ Res 2012;110(8):1125–38. [115] Carreira RS, Lee Y, Ghochani M, Gustafsson ÅB, Gottlieb RA. Cyclophilin D is required for mitochondrial removal by autophagy in cardiac cells. Autophagy 2010;6(4):462–72. [116] Chen W, Feng L, Nie H, Zheng X. Andrographolide induces autophagic cell death in human liver cancer cells through cyclophilin D-mediated mitochondrial permeability transition pore. Carcinogenesis 2012;33(11):2190–8. [117] Hirschey MD, Shimazu T, Huang JY, Schwer B, Verdin E. SIRT3 regulates mitochondrial protein acetylation and intermediary metabolism. Cold Spring Harb Symp Quant Biol 2011;76:267–77. [118] Kincaid B, Bossy-Wetzel E. Forever young: SIRT3 a shield against mitochondrial meltdown, aging, and neurodegeneration. Front Aging Neurosci 2013;5:48. [119] Verma M, Shulga N, Pastorino JG. Sirtuin-3 modulates Bak- and Bax-dependent apoptosis. J Cell Sci 2013;126(Pt 1):274–88. [120] Shulga N, Pastorino JG. Ethanol sensitizes mitochondria to the permeability transition by inhibiting deacetylation of cyclophilin-D mediated by sirtuin-3. J Cell Sci 2010;123(Pt 23):4117–27. [121] Porter GA, Urciuoli WR, Brookes PS, Nadtochiy SM. SIRT3 deficiency exacerbates ischemia–reperfusion injury: implication for aged hearts. Am J Physiol Heart Circ Physiol 2014;306(12):H1602–9. [122] Murphy E, Kohr M, Menazza S, Nguyen T, Evangelista A, Sun J, et al. Signaling by S-nitrosylation in the heart. J Mol Cell Cardiol 2014;73C:18–25. [123] Linard D, Kandlbinder A, Degand H, Morsomme P, Dietz KJ, Knoops B. Redox characterization of human cyclophilin D: identification of a new mammalian mitochondrial redox sensor? Arch Biochem Biophys 2009;491(1–2):39–45. [124] Nguyen TT, Stevens MV, Kohr M, Steenbergen C, Sack MN, Murphy E. Cysteine 203 of cyclophilin D is critical for cyclophilin D activation of the mitochondrial permeability transition pore. J Biol Chem 2011;286(46):40184–92. [125] Kohr MJ, Sun J, Aponte A, Wang G, Gucek M, Murphy E, et al. Simultaneous measurement of protein oxidation and S-nitrosylation during preconditioning and ischemia/ reperfusion injury with resin-assisted capture. Circ Res 2011;108(4):418–26. [126] Hayashi T, Nagasue N, Kohno H, Chang YC, Nakamura T. Beneficial effect of cyclosporine pretreatment in preventing ischemic damage to the liver in dogs. Transplantation 1988;46(6):923–4. [127] Nazareth W, Yafei N, Crompton M. Inhibition of anoxia-induced injury in heart myocytes by cyclosporin A. J Mol Cell Cardiol 1991;23(12):1351–4. [128] Griffiths EJ, Halestrap AP. Protection by Cyclosporin A of ischemia/reperfusioninduced damage in isolated rat hearts. J Mol Cell Cardiol 1993;25(12):1461–9. [129] Hausenloy DJ, Boston-Griffiths EA, Yellon DM. Cyclosporin A and cardioprotection: from investigative tool to therapeutic agent. Br J Pharmacol 2012;165(5):1235–45. [130] Di Lisa F, Menabò R, Canton M, Barile M, Bernardi P. Opening of the mitochondrial permeability transition pore causes depletion of mitochondrial and cytosolic NAD + and is a causative event in the death of myocytes in postischemic reperfusion of the heart. J Biol Chem 2001;276(4):2571–5. [131] Murata M, Akao M, O'Rourke B, Marbán E. Mitochondrial ATP-sensitive potassium channels attenuate matrix Ca(2+) overload during simulated ischemia and reperfusion: possible mechanism of cardioprotection. Circ Res 2001;89(10):891–8. [132] Clarke SJ, McStay GP, Halestrap AP. Sanglifehrin A acts as a potent inhibitor of the mitochondrial permeability transition and reperfusion injury of the heart by binding to cyclophilin-D at a different site from cyclosporin A. J Biol Chem 2002; 277(38):34793–9. [133] Gomez L, Thibault H, Gharib A, Dumont JM, Vuagniaux G, Scalfaro P, et al. Inhibition of mitochondrial permeability transition improves functional recovery and reduces mortality following acute myocardial infarction in mice. Am J Physiol Heart Circ Physiol 2007;293(3):H1654–61. [134] Argaud L, Gateau-Roesch O, Muntean D, Chalabreysse L, Loufouat J, Robert D, et al. Specific inhibition of the mitochondrial permeability transition prevents lethal reperfusion injury. J Mol Cell Cardiol 2005;38(2):367–74.

M.R. Alam et al. / Journal of Molecular and Cellular Cardiology 78 (2015) 80–89 [135] Argaud L, Gateau-Roesch O, Chalabreysse L, Gomez L, Loufouat J, Thivolet-Béjui F, et al. Preconditioning delays Ca2+-induced mitochondrial permeability transition. Cardiovasc Res 2004;61(1):115–22. [136] Piot C, Croisille P, Staat P, Thibault H, Rioufol G, Mewton N, et al. Effect of cyclosporine on reperfusion injury in acute myocardial infarction. N Engl J Med 2008;359(5): 473–81. [137] Lim SY, Davidson SM, Hausenloy DJ, Yellon DM. Preconditioning and postconditioning: the essential role of the mitochondrial permeability transition pore. Cardiovasc Res 2007;75(3):530–5. [138] Di Lisa F, Carpi A, Giorgio V, Bernardi P. The mitochondrial permeability transition pore and cyclophilin D in cardioprotection. Biochim Biophys Acta 2011;1813(7): 1316–22. [139] Cereghetti GM, Stangherlin A, Martins de Brito O, Chang CR, Blackstone C, Bernardi P, et al. Dephosphorylation by calcineurin regulates translocation of Drp1 to mitochondria. Proc Natl Acad Sci U S A 2008;105(41):15803–8. [140] Sharp WW, Fang YH, Han M, Zhang HJ, Hong Z, Banathy A, et al. Dynamin-related protein 1 (Drp1)-mediated diastolic dysfunction in myocardial ischemiareperfusion injury: therapeutic benefits of Drp1 inhibition to reduce mitochondrial fission. FASEB J 2014;28(1):316–26. [141] Kato M, Akao M, Matsumoto-Ida M, Makiyama T, Iguchi M, Takeda T, et al. The targeting of cyclophilin D by RNAi as a novel cardioprotective therapy: evidence from two-photon imaging. Cardiovasc Res 2009;83(2): 335–44. [142] Reichek N, Parcham-Azad K. Reperfusion injury putting the genie back in the bottle? J Am Coll Cardiol 2010;55(12):1206–8.

89

[143] Schneider A, Ad N, Izhar U, Khaliulin I, Borman JB, Schwalb H. Protection of myocardium by cyclosporin A and insulin: in vitro simulated ischemia study in human myocardium. Ann Thorac Surg 2003;76(4):1240–5. [144] Shanmuganathan S, Hausenloy DJ, Duchen MR, Yellon DM. Mitochondrial permeability transition pore as a target for cardioprotection in the human heart. Am J Physiol Heart Circ Physiol 2005;289(1):H237–42. [145] Mewton N, Croisille P, Gahide G, Rioufol G, Bonnefoy E, Sanchez I, et al. Effect of cyclosporine on left ventricular remodeling after reperfused myocardial infarction. J Am Coll Cardiol 2010;55(12):1200–5. [146] Rosenwirth B, Billich A, Datema R, Donatsch P, Hammerschmid F, Harrison R, et al. Inhibition of human immunodeficiency virus type 1 replication by SDZ NIM 811, a nonimmunosuppressive cyclosporine analog. Antimicrob Agents Chemother 1994; 38(8):1763–72. [147] Griffiths EJ, Halestrap AP. Mitochondrial non-specific pores remain closed during cardiac ischaemia, but open upon reperfusion. Biochem J 1995;307(Pt 1):93–8. [148] Sanglier JJ, Quesniaux V, Fehr T, Hofmann H, Mahnke M, Memmert K, et al. Sanglifehrins A, B, C and D, novel cyclophilin-binding compounds isolated from Streptomyces sp. A92-308110. I. Taxonomy, fermentation, isolation and biological activity. J Antibiot (Tokyo) 1999;52(5):466–73. [149] Dube H, Selwood D, Malouitre S, Capano M, Simone MI, Crompton M. A mitochondrial-targeted cyclosporin A with high binding affinity for cyclophilin D yields improved cytoprotection of cardiomyocytes. Biochem J 2012;441(3):901–7.

Inhibition of myocardial reperfusion injury by ischemic postconditioning requires sirtuin 3-mediated deacetylation of cyclophilin D.

Cyclophilin D and acetylation: a new link in cardiac signaling.

American undergraduate pharmacology curriculum: a fresh perspective.

Mitochondrial Cyclophilin D in Vascular Oxidative Stress and Hypertension.

reperfusion injury and necrotic cell death.

Protective Effects of D-Penicillamine on Catecholamine-Induced Myocardial Injury.

Inhibition of cyclophilin D by cyclosporin A promotes retinal ganglion cell survival by preventing mitochondrial alteration in ischemic injury.

Forum focus. Get a fresh perspective on emerging issues.

Adult-onset foveomacular vitelliform dystrophy: A fresh perspective.

Knockout of Cyclophilin-D Provides Partial Amelioration of Intrinsic and Synaptic Properties Altered by Mild Traumatic Brain Injury.

[Treatment of fresh muscle injury].

Characterization of cyclophilin D in freshwater pearl mussel (Hyriopsis schlegelii).

Acute myocardial infarction and myocardial ischemia-reperfusion injury: a comparison.

D-Dimer Levels Predict Myocardial Injury in ST-Segment Elevation Myocardial Infarction: A Cardiac Magnetic Resonance Imaging Study.

Perspective: Avoiding injury.

Head Injury- A Maxillofacial Surgeon's Perspective.

Sunlight and Vitamin D: A global perspective for health.

Vitamin D status, hypertension and ischemic stroke: a clinical perspective.

Mycobacterium abscessus glycopeptidolipids inhibit macrophage apoptosis and bacterial spreading by targeting mitochondrial cyclophilin D.

Human cyclophilin B: a second cyclophilin gene encodes a peptidyl-prolyl isomerase with a signal sequence.

Cyclophilin A in cardiovascular homeostasis and diseases.

Regulation of necrotic cell death: p53, PARP1 and cyclophilin D-overlapping pathways of regulated necrosis?

F1F0 ATP Synthase-Cyclophilin D Interaction Contributes to Diabetes-Induced Synaptic Dysfunction and Cognitive Decline.

Reperfusion Injury in Langendorff-Perfused Rat Hearts.