Cell Death in the Pathogenesis of Heart Disease: Mechanisms and Significance
TL;DR: Pharmacological and genetic inhibition of apoptosis and necrosis lessens infarct size and improves cardiac function in these disorders and a better understanding of these processes and their interrelationships may allow for the development of novel therapies for the major heart syndromes.
Abstract: Cell death was once viewed as unregulated. It is now clear that at least a portion of cell death is a regulated cell suicide process. This type of death can exhibit multiple morphologies. One of these, apoptosis, has long been recognized to be actively mediated, and many of its underlying mechanisms have been elucidated. Moreover, necrosis, the traditional example of unregulated cell death, is also regulated in some instances. Autophagy is usually a survival mechanism but can occur in association with cell death. Little is known, however, about how autophagic cells die. Apoptosis, necrosis, and autophagy occur in cardiac myocytes during myocardial infarction, ischemia/reperfusion, and heart failure. Pharmacological and genetic inhibition of apoptosis and necrosis lessens infarct size and improves cardiac function in these disorders. The roles of autophagy in ischemia/reperfusion and heart failure are unresolved. A better understanding of these processes and their interrelationships may allow for the development of novel therapies for the major heart syndromes.
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TL;DR: It is apparent that a combination of molecular and cellular approaches targeting multiple pathologic processes to limit the extent of I/R injury must be adopted to enhance resistance to cell death and increase regenerative capacity in order to effect long-lasting repair of ischemic tissues.
Abstract: Disorders characterized by ischemia/reperfusion (I/R), such as myocardial infarction, stroke, and peripheral vascular disease, continue to be among the most frequent causes of debilitating disease and death. Tissue injury and/or death occur as a result of the initial ischemic insult, which is determined primarily by the magnitude and duration of the interruption in the blood supply, and then subsequent damage induced by reperfusion. During prolonged ischemia, ATP levels and intracellular pH decrease as a result of anaerobic metabolism and lactate accumulation. As a consequence, ATPase-dependent ion transport mechanisms become dysfunctional, contributing to increased intracellular and mitochondrial calcium levels (calcium overload), cell swelling and rupture, and cell death by necrotic, necroptotic, apoptotic, and autophagic mechanisms. Although oxygen levels are restored upon reperfusion, a surge in the generation of reactive oxygen species occurs and proinflammatory neutrophils infiltrate ischemic tissues to exacerbate ischemic injury. The pathologic events induced by I/R orchestrate the opening of the mitochondrial permeability transition pore, which appears to represent a common end-effector of the pathologic events initiated by I/R. The aim of this treatise is to provide a comprehensive review of the mechanisms underlying the development of I/R injury, from which it should be apparent that a combination of molecular and cellular approaches targeting multiple pathologic processes to limit the extent of I/R injury must be adopted to enhance resistance to cell death and increase regenerative capacity in order to effect long-lasting repair of ischemic tissues.
1,565 citations
Cites background from "Cell Death in the Pathogenesis of H..."
...Caspase-3 acts as the cell’s executioner by proteolyzing many cellular proteins (Broughton et al., 2009; Kroemer et al., 2007; Whelan et al., 2010)....
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...6.4), although there is considerable cross talk between the two (Broughton et al., 2009; Kroemer et al., 2007; Whelan et al., 2010)....
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..., Bax, Bak) into the outer mitochondrial membrane (Broughton et al., 2009; Kroemer et al., 2007; Whelan et al., 2010)....
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...…leading to dissipation of the proton electrochemical gradient, with subsequent ATP depletion, further ROS production, and swelling and rupture of mitochondrial membranes. respectively, whereas endoG mediates DNA fragmentation (Broughton et al., 2009; Kroemer et al., 2007; Whelan et al., 2010)....
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...4), although there is considerable cross talk between the two (Broughton et al., 2009; Kroemer et al., 2007; Whelan et al., 2010)....
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TL;DR: It is discovered and demonstrated that ferroptosis, a programmed iron-dependent cell death, as a mechanism in murine models of doxorubicin (DOX)- and ischemia/reperfusion (I/R)-induced cardiomyopathy and Mitochondria-targeted antioxidant MitoTEMPO significantly rescued DOX cardiopathy, supporting oxidative damage of mitochondria as a major mechanism in ferroPTosis-induced heart damage.
Abstract: Heart disease is the leading cause of death worldwide. A key pathogenic factor in the development of lethal heart failure is loss of terminally differentiated cardiomyocytes. However, mechanisms of cardiomyocyte death remain unclear. Here, we discovered and demonstrated that ferroptosis, a programmed iron-dependent cell death, as a mechanism in murine models of doxorubicin (DOX)- and ischemia/reperfusion (I/R)-induced cardiomyopathy. In canonical apoptosis and/or necroptosis-defective Ripk3−/−, Mlkl−/−, or Fadd−/−Mlkl−/− mice, DOX-treated cardiomyocytes showed features of typical ferroptotic cell death. Consistently, compared with dexrazoxane, the only FDA-approved drug for treating DOX-induced cardiotoxicity, inhibition of ferroptosis by ferrostatin-1 significantly reduced DOX cardiomyopathy. RNA-sequencing results revealed that heme oxygenase-1 (Hmox1) was significantly up-regulated in DOX-treated murine hearts. Administering DOX to mice induced cardiomyopathy with a rapid, systemic accumulation of nonheme iron via heme degradation by Nrf2-mediated up-regulation of Hmox1, which effect was abolished in Nrf2-deficent mice. Conversely, zinc protoporphyrin IX, an Hmox1 antagonist, protected the DOX-treated mice, suggesting free iron released on heme degradation is necessary and sufficient to induce cardiac injury. Given that ferroptosis is driven by damage to lipid membranes, we further investigated and found that excess free iron accumulated in mitochondria and caused lipid peroxidation on its membrane. Mitochondria-targeted antioxidant MitoTEMPO significantly rescued DOX cardiomyopathy, supporting oxidative damage of mitochondria as a major mechanism in ferroptosis-induced heart damage. Importantly, ferrostatin-1 and iron chelation also ameliorated heart failure induced by both acute and chronic I/R in mice. These findings highlight that targeting ferroptosis serves as a cardioprotective strategy for cardiomyopathy prevention.
918 citations
Cites background from "Cell Death in the Pathogenesis of H..."
...Preventing cardiac cell death has been suggested to be an effective cardioprotective strategy (34)....
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Journal Article•
TL;DR: Cardiac myocyte apoptosis is a critical point in the transition between compensatory cardiac hypertrophy and heart failure and gp130-dependent cytokines may represent a novel therapeutic strategy for preventing in vivo heart failure.
Abstract: Biomechanical stress is a major stimulus for cardiac hypertrophy and the transition to heart failure. By generating mice that harbor a ventricular restricted knockout of the gp130 cytokine receptor via Cre-IoxP-mediated recombination, we demonstrate a critical role for a gp130-dependent myocyte survival pathway in the transition to heart failure. Such conditional mutant mice have normal cardiac structure and function, but during aortic pressure overload, these mice display rapid onset of dilated cardiomyopathy and massive induction of myocyte apoptosis versus the control mice that exhibit compensatory hypertrophy. Thus, cardiac myocyte apoptosis is a critical point in the transition between compensatory cardiac hypertrophy and heart failure. gp130-dependent cytokines may represent a novel therapeutic strategy for preventing in vivo heart failure.
641 citations
TL;DR: This work discusses the different strategies that are used to prevent cell death and illustrates that although anti-apoptosis and cellular survival serve to counteract PCD, they are nevertheless mechanistically distinct from the processes that regulate cell death.
587 citations
Cites background from "Cell Death in the Pathogenesis of H..."
...Parkinson`s as well a number of pathophysiological processes such as ischemic strokes and heart attacks [8,41,55,334]....
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...This relatively simple example of cross-talk between apparently distinct apoptotic pathways further serves to illustrate a common theme of the complex interrelationships that is now commonly observed in the different processes involved in regulating cell death (see also below) [8,13,17,18]....
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TL;DR: It is shown that receptor-interacting protein 3 (RIP3) triggers myocardial necroptosis, in addition to apoptosis and inflammation, through activation of Ca2+-calmodulin–dependent protein kinase (CaMKII) rather than through the well-established RIP3 partners RIP1 and MLKL.
Abstract: Regulated necrosis (necroptosis) and apoptosis are crucially involved in severe cardiac pathological conditions, including myocardial infarction, ischemia-reperfusion injury and heart failure. Whereas apoptotic signaling is well defined, the mechanisms that underlie cardiomyocyte necroptosis remain elusive. Here we show that receptor-interacting protein 3 (RIP3) triggers myocardial necroptosis, in addition to apoptosis and inflammation, through activation of Ca(2+)-calmodulin-dependent protein kinase (CaMKII) rather than through the well-established RIP3 partners RIP1 and MLKL. In mice, RIP3 deficiency or CaMKII inhibition ameliorates myocardial necroptosis and heart failure induced by ischemia-reperfusion or by doxorubicin treatment. RIP3-induced activation of CaMKII, via phosphorylation or oxidation or both, triggers opening of the mitochondrial permeability transition pore and myocardial necroptosis. These findings identify CaMKII as a new RIP3 substrate and delineate a RIP3-CaMKII-mPTP myocardial necroptosis pathway, a promising target for the treatment of ischemia- and oxidative stress-induced myocardial damage and heart failure.
533 citations
References
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TL;DR: Mutation of the active site of caspase-9 attenuated the activation of cazase-3 and cellular apoptotic response in vivo, indicating that casp enzyme-9 is the most upstream member of the apoptotic protease cascade that is triggered by cytochrome c and dATP.
7,231 citations
TL;DR: This Review summarizes recent advances in understanding the physiological functions of autophagy and its possible roles in the causation and prevention of human diseases.
6,301 citations
TL;DR: In a cell-free apoptosis system, mitochondria spontaneously released cytochrome c, which activated DEVD-specific caspases, leading to fodrin cleavage and apoptotic nuclear morphology, and Bcl-2 acts to inhibit cy tochrome c translocation, thereby blocking caspase activation and the apoptotic process.
Abstract: In a cell-free apoptosis system, mitochondria spontaneously released cytochrome c, which activated DEVD-specific caspases, leading to fodrin cleavage and apoptotic nuclear morphology. Bcl-2 acted in situ on mitochondria to prevent the release of cytochrome c and thus caspase activation. During apoptosis in intact cells, cytochrome c translocation was similarly blocked by Bcl-2 but not by a caspase inhibitor, zVAD-fmk. In vitro, exogenous cytochrome c bypassed the inhibitory effect of Bcl-2. Cytochrome c release was unaccompanied by changes in mitochondrial membrane potential. Thus, Bcl-2 acts to inhibit cytochrome c translocation, thereby blocking caspase activation and the apoptotic process.
4,754 citations
TL;DR: The results indicate that BID is a mediator of mitochondrial damage induced by Casp8, and coexpression of BclxL inhibits all the apoptotic changes induced by tBID.
4,556 citations
TL;DR: New insights into interactions among BCL-2 family proteins reveal how these proteins are regulated, but a unifying hypothesis for the mechanisms they use to activate caspases remains elusive.
Abstract: BCL-2 family proteins, which have either pro- or anti-apoptotic activities, have been studied intensively for the past decade owing to their importance in the regulation of apoptosis, tumorigenesis and cellular responses to anti-cancer therapy. They control the point of no return for clonogenic cell survival and thereby affect tumorigenesis and host-pathogen interactions and regulate animal development. Recent structural, phylogenetic and biological analyses, however, suggest the need for some reconsideration of the accepted organizational principles of the family and how the family members interact with one another during programmed cell death. Although these insights into interactions among BCL-2 family proteins reveal how these proteins are regulated, a unifying hypothesis for the mechanisms they use to activate caspases remains elusive.
4,246 citations