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Carobbio S, Rodriguez-Cuenca S, Vidal-Puig A. Origins of metabolic complications in obesity: ectopic fat accumulation. The importance of the qualitative aspect of lipotoxicity. Curr Opin Clin Nutr Metab Care 2011; 14:520-6. [PMID: 21849895 DOI: 10.1097/mco.0b013e32834ad966] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
PURPOSE OF REVIEW This study highlights two aspects of the concept of lipotoxicity. First, the metabolic consequences following ectopic fat accumulation are not only determined by the amount of lipid accumulated, but also the quality of lipid species. Second, the existence of allostatic mechanisms operating at cellular and tissue levels, which counterbalance the negative effects of lipid overload. RECENT FINDINGS The development of lipidomics has allowed the isolation and identification of a wide range of lipid species. Some are highly reactive and capable of inducing undesirable toxic effects. Here we focus on recent information related to pathways involved in the production of these reactive lipid species, their sites of generation and tropism for specific organelles and the molecular mechanisms through which they exert toxic effects. We describe how cell membranes and the lipid species forming their bilayer constitute the main platform from which reactive lipid species are generated. We propose that strategies aimed at maintaining membrane lipid homeostasis are fundamental to preventing the initiation of metabolically relevant lipotoxicity. SUMMARY It is essential to understand the qualitative component of lipid species involved in cellular toxicity and the molecular mechanisms mediating these toxic effects to identify new therapeutic targets.
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Affiliation(s)
- Stefania Carobbio
- University of Cambridge, Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Institute of Metabolic Science, University of Cambridge, Cambridge, UK
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152
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Abstract
Apoptosis is a tightly regulated physiologic process of programmed cell death that occurs in both normal and pathologic tissues. Numerous in vitro or in vivo studies have indicated that cardiomyocyte death through apoptosis and necrosis is a primary contributor to the progression of anthracycline-induced cardiomyopathy. There are now several pieces of evidence to suggest that activation of intrinsic and extrinsic apoptotic pathways contribute to anthracycline-induced apoptosis in the heart. Novel strategies were developed to address a wide variety of cardiotoxic mechanisms and apoptotic pathways by which anthracycline influences cardiac structure and function. Anthracycline-induced apoptosis provides a very valid representation of cardiotoxicity in the heart, an argument which has implications for the most appropriate animal models of damaged heart plus diverse pharmacological effects. In this review we describe various aspects of the current understanding of apoptotic cell death triggered by anthracycline. Differences in the sensitivity to anthracycline-induced apoptosis between young and adult hearts are also discussed.
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Affiliation(s)
- Jianjian Shi
- Riley Heart Research Center, Wells Center for Pediatric Research, Department of Pediatrics Indiana University, School of Medicine, Indianapolis, Indiana, USA
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153
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Zungu M, Schisler J, Willis MS. All the little pieces. -Regulation of mitochondrial fusion and fission by ubiquitin and small ubiquitin-like modifer and their potential relevance in the heart.-. Circ J 2011; 75:2513-21. [PMID: 22001293 DOI: 10.1253/circj.cj-11-0967] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mitochondria are dynamic organelles that undergo a constant cycle of division and fusion to maintain their function. The process of mitochondrial fusion has the effect of mixing their content, allowing complementation of protein components, mtDNA repair, and distribution of metabolic intermediates. Fission, on the other hand, enables mitochondria to increase in number and capacity, and to segregate mitochondria for autophagy by the lysosome ("mitophagy"). Disruption of these protein quality control mechanisms has recently been identified in multiple cardiac diseases, including cardiac hypertrophy, heart failure, dilated cardiomyopathy, and ischemic heart disease, and is intimately tied to mitochondrial control of apoptosis. Proteins that regulate mitochondrial fusion and fission have been discovered, including Mfn1, Mfn2, and Opa1 (fusion) and Drp1 and Fis1 (fission). In this review, we discuss how these proteins are regulated by post-translational modification with ubiquitin and SUMO (small ubiquitin-like modifier). We then present what is known about the ubiquitin and SUMO ligases that regulate these post-translational modifications and regulation of mitochondrial fusion and fission, exploring their potential as therapeutic targets of cardiac disease.
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Affiliation(s)
- Makhosazane Zungu
- Department of Pathology & Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA
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154
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155
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Szendroedi J, Phielix E, Roden M. The role of mitochondria in insulin resistance and type 2 diabetes mellitus. Nat Rev Endocrinol 2011; 8:92-103. [PMID: 21912398 DOI: 10.1038/nrendo.2011.138] [Citation(s) in RCA: 421] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Type 2 diabetes mellitus (T2DM) has been related to alterations of oxidative metabolism in insulin-responsive tissues. Overt T2DM can present with acquired or inherited reductions of mitochondrial oxidative phosphorylation capacity, submaximal ADP-stimulated oxidative phosphorylation and plasticity of mitochondria and/or lower mitochondrial content in skeletal muscle cells and potentially also in hepatocytes. Acquired insulin resistance is associated with reduced insulin-stimulated mitochondrial activity as the result of blunted mitochondrial plasticity. Hereditary insulin resistance is frequently associated with reduced mitochondrial activity at rest, probably due to diminished mitochondrial content. Lifestyle and pharmacological interventions can enhance the capacity for oxidative phosphorylation and mitochondrial content and improve insulin resistance in some (pre)diabetic cases. Various mitochondrial features can be abnormal but are not necessarily responsible for all forms of insulin resistance. Nevertheless, mitochondrial abnormalities might accelerate progression of insulin resistance and subsequent organ dysfunction via increased production of reactive oxygen species. This Review discusses the association between mitochondrial function and insulin sensitivity in various tissues, such as skeletal muscle, liver and heart, with a main focus on studies in humans, and addresses the effects of therapeutic strategies that affect mitochondrial function and insulin sensitivity.
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Affiliation(s)
- Julia Szendroedi
- Institute for Clinical Diabetology, German Diabetes Center, D-40225 Düsseldorf, Germany
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156
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Schlapp G, Scavone P, Zunino P, Härtel S. Development of 3D architecture of uropathogenic Proteus mirabilis batch culture biofilms-A quantitative confocal microscopy approach. J Microbiol Methods 2011; 87:234-40. [PMID: 21864585 DOI: 10.1016/j.mimet.2011.07.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 07/25/2011] [Accepted: 07/28/2011] [Indexed: 10/17/2022]
Abstract
This work studies the development of the 3D architecture of batch culture P. mirabilis biofilms on the basis of morpho-topological descriptors calculated from confocal laser scanning microscopy (CLSM) stacks with image processing routines. A precise architectonical understanding of biofilm organization on a morpho-topological level is necessary to understand emergent interactions with the environment and the appearance of functionally different progeny swarmer cells. P. mirabilis biofilms were grown on glass coverslips for seven days on LB broth and subjected to in situ immunofluorescence. Confocal image stacks were deconvolved prior to segmentation of regions of interest (ROI) that identify individual bacteria and extracellular material, followed by 3D reconstruction and calculation of different morpho-topological key descriptors. Results showed that P. mirabilis biofilm formation followed a five stage process: (i) reversible adhesion to the surface characterized by slow growth, presence of elongated bacteria, and absence of extracellular material, (ii) irreversible bacterial adhesion concomitant to decreasing elongation, and the beginning of extracellular polymer production, (iii) accelerated bacterial growth concomitant to continuously decreasing elongation and halting of extracellular polymer production, (iv) maturation of biofilm defined by maximum bacterial density, volume, minimum elongation, maximum extracellular material, and highest compaction, and (v) decreased bacterial density and extracellular material through detachment and dispersion. Swarmer cells do not play a role in P. mirabilis biofilm formation under the applied conditions. Our approach sets the basis for future studies of 3D biofilm architecture using dynamic in vivo models and different environmental conditions that assess clinical impacts of P. mirabilis biofilm.
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Affiliation(s)
- G Schlapp
- Department of Microbiology, Instituto de Investigaciones Biológicas Clemente Estable, Avda. Italia 3318, Montevideo, Uruguay
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157
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Kuzmicic J, Del Campo A, López-Crisosto C, Morales PE, Pennanen C, Bravo-Sagua R, Hechenleitner J, Zepeda R, Castro PF, Verdejo HE, Parra V, Chiong M, Lavandero S. [Mitochondrial dynamics: a potential new therapeutic target for heart failure]. Rev Esp Cardiol 2011; 64:916-23. [PMID: 21820793 DOI: 10.1016/j.recesp.2011.05.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 05/31/2011] [Indexed: 12/19/2022]
Abstract
Mitochondria are dynamic organelles able to vary their morphology between elongated interconnected mitochondrial networks and fragmented disconnected arrays, through events of mitochondrial fusion and fission, respectively. These events allow the transmission of signaling messengers and exchange of metabolites within the cell. They have also been implicated in a variety of biological processes including embryonic development, metabolism, apoptosis, and autophagy. Although the majority of these studies have been confined to noncardiac cells, emerging evidence suggests that changes in mitochondrial morphology could participate in cardiac development, the response to ischemia-reperfusion injury, heart failure, and diabetes mellitus. In this article, we review how the mitochondrial dynamics are altered in different cardiac pathologies, with special emphasis on heart failure, and how this knowledge may provide new therapeutic targets for treating cardiovascular diseases.
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Affiliation(s)
- Jovan Kuzmicic
- Centro Estudios Moleculares de la Célula, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
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158
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Di Lisa F, Carpi A, Giorgio V, Bernardi P. The mitochondrial permeability transition pore and cyclophilin D in cardioprotection. BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1813:1316-22. [PMID: 21295622 DOI: 10.1016/j.bbamcr.2011.01.031] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 01/18/2011] [Accepted: 01/26/2011] [Indexed: 01/12/2023]
Abstract
Mitochondria play a central role in heart energy metabolism and Ca(2+) homeostasis and are involved in the pathogenesis of many forms of heart disease. The body of knowledge on mitochondrial pathophysiology in living cells and organs is increasing, and so is the interest in mitochondria as potential targets for cardioprotection. This critical review will focus on the permeability transition pore (PTP) and its regulation by cyclophilin (CyP) D as effectors of endogenous protective mechanisms and as potential drug targets. The complexity of the regulatory interactions underlying control of mitochondrial function in vivo is beginning to emerge, and although apparently contradictory findings still exist we believe that the network of regulatory protein interactions involving the PTP and CyPs in physiology and pathology will increase our repertoire for therapeutic interventions in heart disease. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.
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Affiliation(s)
- Fabio Di Lisa
- Department of Biomedical Sciences and CNR Institute of Neuroscience, University of Padova, 35121 Padova, Italy.
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159
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Bravo R, Vicencio JM, Parra V, Troncoso R, Munoz JP, Bui M, Quiroga C, Rodriguez AE, Verdejo HE, Ferreira J, Iglewski M, Chiong M, Simmen T, Zorzano A, Hill JA, Rothermel BA, Szabadkai G, Lavandero S. Increased ER-mitochondrial coupling promotes mitochondrial respiration and bioenergetics during early phases of ER stress. J Cell Sci 2011; 124:2143-52. [PMID: 21628424 PMCID: PMC3113668 DOI: 10.1242/jcs.080762] [Citation(s) in RCA: 435] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/02/2011] [Indexed: 01/02/2023] Open
Abstract
Increasing evidence indicates that endoplasmic reticulum (ER) stress activates the adaptive unfolded protein response (UPR), but that beyond a certain degree of ER damage, this response triggers apoptotic pathways. The general mechanisms of the UPR and its apoptotic pathways are well characterized. However, the metabolic events that occur during the adaptive phase of ER stress, before the cell death response, remain unknown. Here, we show that, during the onset of ER stress, the reticular and mitochondrial networks are redistributed towards the perinuclear area and their points of connection are increased in a microtubule-dependent fashion. A localized increase in mitochondrial transmembrane potential is observed only in redistributed mitochondria, whereas mitochondria that remain in other subcellular zones display no significant changes. Spatial re-organization of these organelles correlates with an increase in ATP levels, oxygen consumption, reductive power and increased mitochondrial Ca²⁺ uptake. Accordingly, uncoupling of the organelles or blocking Ca²⁺ transfer impaired the metabolic response, rendering cells more vulnerable to ER stress. Overall, these data indicate that ER stress induces an early increase in mitochondrial metabolism that depends crucially upon organelle coupling and Ca²⁺ transfer, which, by enhancing cellular bioenergetics, establishes the metabolic basis for the adaptation to this response.
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Affiliation(s)
- Roberto Bravo
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Jose Miguel Vicencio
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
- Department of Cell and Developmental Biology and Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK
| | - Valentina Parra
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Rodrigo Troncoso
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Juan Pablo Munoz
- Institute for Research in Biomedicine (IRB Barcelona) and Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona 08028, Spain
| | - Michael Bui
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Clara Quiroga
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Andrea E. Rodriguez
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Hugo E. Verdejo
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
- Department of Cardiovascular Diseases, Faculty of Medicine, P. Catholic University of Chile, Santiago, Chile
| | - Jorge Ferreira
- Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Myriam Iglewski
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mario Chiong
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Thomas Simmen
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Antonio Zorzano
- Institute for Research in Biomedicine (IRB Barcelona) and Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona 08028, Spain
| | - Joseph A. Hill
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Beverly A. Rothermel
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Gyorgy Szabadkai
- Department of Cell and Developmental Biology and Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK
| | - Sergio Lavandero
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
- Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago 8380492, Chile
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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160
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A novel parthenin analog exhibits anti-cancer activity: activation of apoptotic signaling events through robust NO formation in human leukemia HL-60 cells. Chem Biol Interact 2011; 193:204-15. [PMID: 21741372 DOI: 10.1016/j.cbi.2011.06.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2011] [Revised: 06/08/2011] [Accepted: 06/15/2011] [Indexed: 12/11/2022]
Abstract
This study describes the anti-cancer activity of P19, an analog of parthenin. P19 induced apoptosis in HL-60 cells and inhibited cell proliferation with 48h IC50 of 3.5μM. At 10mg/kg dose, it doubled the median survival time of L1210 leukemic mice and at 25mg/kg it inhibited Ehrlich ascites tumor growth by 60%. Investigation of the mechanism of P19 induced apoptosis in HL-60 cells revealed that N-acetyl-l-cysteine (NAC) and s-methylisothiourea (sMIT) could reverse several molecular events that lead to cell death by inhibiting nitric oxide (NO) formation. It selectively produced massive NO in cells while quenching the basal ROS levels with concurrent elevation of GSH. P19 disrupted mitochondrial integrity leading to cytochrome c release and caspase-9 activation. P19 also caused caspase-8 activation by selectively elevating the expression of DR4 and DR5. All these events lead to the activation of caspase-3 leading to PARP-1 cleavage and DNA fragmentation. However, knocking down of AIF by siRNA also suppressed the apoptosis substantially thus indicating caspase independent apoptosis, too. Further, contrary to enhanced iNOS expression, its transcription factor, NF-κB (p65) was cleaved with a simultaneous increase in cytosolic IκB-alpha. In addition, P19 potently inhibited pro-survival proteins pSTAT3 and survivin. The multi-modal pro-apoptotic activity of P19 raises its potential usefulness as a promising anti-cancer therapeutic.
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161
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Abstract
Mitochondria are highly dynamic organelles, capable of undergoing constant fission and fusion events, forming networks. These dynamic events allow the transmission of chemical and physical messengers and the exchange of metabolites within the cell. In this article we review the signaling mechanisms controlling mitochondrial fission and fusion, and its relationship with cell bioenergetics, especially in the heart. Furthermore we also discuss how defects in mitochondrial dynamics might be involved in the pathogenesis of metabolic cardiac diseases.
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162
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A cyano analogue of boswellic acid induces crosstalk between p53/PUMA/Bax and telomerase that stages the human papillomavirus type 18 positive HeLa cells to apoptotic death. Eur J Pharmacol 2011; 660:241-8. [DOI: 10.1016/j.ejphar.2011.03.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 02/23/2011] [Accepted: 03/17/2011] [Indexed: 02/04/2023]
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163
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Iglewski M, Hill JA, Lavandero S, Rothermel BA. Mitochondrial fission and autophagy in the normal and diseased heart. Curr Hypertens Rep 2011; 12:418-25. [PMID: 20865352 DOI: 10.1007/s11906-010-0147-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Sustained hypertension promotes structural, functional and metabolic remodeling of cardiomyocyte mitochondria. As long-lived, postmitotic cells, cardiomyocytes turn over mitochondria continuously to compensate for changes in energy demands and to remove damaged organelles. This process involves fusion and fission of existing mitochondria to generate new organelles and separate old ones for degradation via autophagy. Autophagy is a lysosome-dependent proteolytic pathway capable of processing cellular components, including organelles and protein aggregates. Autophagy can be either nonselective or selective and contributes to remodeling of the myocardium under stress. Fission of mitochondria, loss of membrane potential, and ubiquitination are emerging as critical steps that direct selective autophagic degradation of mitochondria. This review discusses the molecular mechanisms controlling mitochondrial dynamics, including fission, fusion, transport, and degradation. Furthermore, it examines recent studies revealing the importance of these processes in normal and diseased heart.
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Affiliation(s)
- Myriam Iglewski
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390-8573, USA
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164
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Paula-Lima AC, Adasme T, SanMartín C, Sebollela A, Hetz C, Carrasco MA, Ferreira ST, Hidalgo C. Amyloid β-peptide oligomers stimulate RyR-mediated Ca2+ release inducing mitochondrial fragmentation in hippocampal neurons and prevent RyR-mediated dendritic spine remodeling produced by BDNF. Antioxid Redox Signal 2011; 14:1209-23. [PMID: 20712397 DOI: 10.1089/ars.2010.3287] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Soluble amyloid β-peptide oligomers (AβOs), increasingly recognized as causative agents of Alzheimer's disease (AD), disrupt neuronal Ca(2+) homeostasis and synaptic function. Here, we report that AβOs at sublethal concentrations generate prolonged Ca(2+) signals in primary hippocampal neurons; incubation in Ca(2+)-free solutions, inhibition of ryanodine receptors (RyRs) or N-methyl-d-aspartate receptors (NMDARs), or preincubation with N-acetyl-l-cysteine abolished these signals. AβOs decreased (6 h) RyR2 and RyR3 mRNA and RyR2 protein, and promoted mitochondrial fragmentation after 24 h. NMDAR inhibition abolished the RyR2 decrease, whereas RyR inhibition prevented significantly the RyR2 protein decrease and mitochondrial fragmentation induced by AβOs. Incubation with AβOs (6 h) eliminated the RyR2 increase induced by brain-derived nerve factor (BDNF) and the dendritic spine remodeling induced within minutes by BDNF or the RyR agonist caffeine. Addition of BDNF to neurons incubated with AβOs for 24 h, which had RyR2 similar to and slightly higher RyR3 protein content than those of controls, induced dendritic spine growth but at slower rates than in controls. These combined effects of sublethal AβOs concentrations (which include redox-sensitive stimulation of RyR-mediated Ca(2+) release, decreased RyR2 protein expression, mitochondrial fragmentation, and prevention of RyR-mediated spine remodeling) may contribute to impairing the synaptic plasticity in AD.
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Affiliation(s)
- Andrea C Paula-Lima
- Centro de Estudios Moleculares de la Célula, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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165
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Di Lisa F, Canton M, Carpi A, Kaludercic N, Menabò R, Menazza S, Semenzato M. Mitochondrial injury and protection in ischemic pre- and postconditioning. Antioxid Redox Signal 2011; 14:881-91. [PMID: 20615074 DOI: 10.1089/ars.2010.3375] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mitochondrial damage is a determining factor in causing loss of cardiomyocyte function and viability, yet a mild degree of mitochondrial dysfunction appears to underlie cardioprotection against injury caused by postischemic reperfusion. This review is focused on two major mechanisms of mitochondrial dysfunction, namely, oxidative stress and opening of the mitochondrial permeability transition pore. The formation of reactive oxygen species in mitochondria will be analyzed with regard to factors controlling mitochondrial permeability transition pore opening. Finally, these mitochondrial processes are analyzed with respect to cardioprotection afforded by ischemic pre- and postconditioning.
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Affiliation(s)
- Fabio Di Lisa
- Department of Biomedical Sciences, Università di Padova, Viale G. Colombo 3, Padua, Italy.
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166
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Papanicolaou KN, Khairallah RJ, Ngoh GA, Chikando A, Luptak I, O'Shea KM, Riley DD, Lugus JJ, Colucci WS, Lederer WJ, Stanley WC, Walsh K. Mitofusin-2 maintains mitochondrial structure and contributes to stress-induced permeability transition in cardiac myocytes. Mol Cell Biol 2011; 31:1309-28. [PMID: 21245373 PMCID: PMC3067905 DOI: 10.1128/mcb.00911-10] [Citation(s) in RCA: 295] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 09/10/2010] [Accepted: 12/17/2010] [Indexed: 11/20/2022] Open
Abstract
Mitofusin-2 (Mfn-2) is a dynamin-like protein that is involved in the rearrangement of the outer mitochondrial membrane. Research using various experimental systems has shown that Mfn-2 is a mediator of mitochondrial fusion, an evolutionarily conserved process responsible for the surveillance of mitochondrial homeostasis. Here, we find that cardiac myocyte mitochondria lacking Mfn-2 are pleiomorphic and have the propensity to become enlarged. Consistent with an underlying mild mitochondrial dysfunction, Mfn-2-deficient mice display modest cardiac hypertrophy accompanied by slight functional deterioration. The absence of Mfn-2 is associated with a marked delay in mitochondrial permeability transition downstream of Ca(2+) stimulation or due to local generation of reactive oxygen species (ROS). Consequently, Mfn-2-deficient adult cardiomyocytes are protected from a number of cell death-inducing stimuli and Mfn-2 knockout hearts display better recovery following reperfusion injury. We conclude that in cardiac myocytes, Mfn-2 controls mitochondrial morphogenesis and serves to predispose cells to mitochondrial permeability transition and to trigger cell death.
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Affiliation(s)
- Kyriakos N. Papanicolaou
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
| | - Ramzi J. Khairallah
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
| | - Gladys A. Ngoh
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
| | - Aristide Chikando
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
| | - Ivan Luptak
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
| | - Karen M. O'Shea
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
| | - Dushon D. Riley
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
| | - Jesse J. Lugus
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
| | - Wilson S. Colucci
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
| | - W. Jonathan Lederer
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
| | - William C. Stanley
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
| | - Kenneth Walsh
- Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, W611, Boston, Massachusetts 02118, Division of Cardiology and Department of Medicine, University of Maryland, 20 Penn Street, HSF2, Room S022, Baltimore, Maryland 21201, Cardiovascular Medicine Section and Myocardial Biology Unit, Boston University Medical Center, 715 Albany Street, X704, Boston, Massachusetts 02118, Center for Biomedical Engineering and Technology, University of Maryland Baltimore, 725 W. Lombard Street, Baltimore, Maryland 21201
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167
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White JP, Baltgalvis KA, Puppa MJ, Sato S, Baynes JW, Carson JA. Muscle oxidative capacity during IL-6-dependent cancer cachexia. Am J Physiol Regul Integr Comp Physiol 2010; 300:R201-11. [PMID: 21148472 DOI: 10.1152/ajpregu.00300.2010] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Many diseases are associated with catabolic conditions that induce skeletal muscle wasting. These various catabolic states may have similar and distinct mechanisms for inducing muscle protein loss. Mechanisms related to muscle wasting may also be related to muscle metabolism since glycolytic muscle fibers have greater wasting susceptibility with several diseases. The purpose of this study was to determine the relationship between muscle oxidative capacity and muscle mass loss in red and white hindlimb muscles during cancer cachexia development in the Apc(Min/+) mouse. Gastrocnemius and soleus muscles were excised from Apc(Min/+) mice at 20 wk of age. The gastrocnemius muscle was partitioned into red and white portions. Body mass (-20%), gastrocnemius muscle mass (-41%), soleus muscle mass (-34%), and epididymal fat pad (-100%) were significantly reduced in severely cachectic mice (n = 8) compared with mildly cachectic mice (n = 6). Circulating IL-6 was fivefold higher in severely cachectic mice. Cachexia significantly reduced the mitochondrial DNA-to-nuclear DNA ratio in both red and white portions of the gastrocnemius. Cytochrome c and cytochrome-c oxidase complex subunit IV (Cox IV) protein were reduced in all three muscles with severe cachexia. Changes in muscle oxidative capacity were not associated with altered myosin heavy chain expression. PGC-1α expression was suppressed by cachexia in the red and white gastrocnemius and soleus muscles. Cachexia reduced Mfn1 and Mfn2 mRNA expression and markers of oxidative stress, while Fis1 mRNA was increased by cachexia in all muscle types. Muscle oxidative capacity, mitochondria dynamics, and markers of oxidative stress are reduced in both oxidative and glycolytic muscle with severe wasting that is associated with increased circulating IL-6 levels.
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Affiliation(s)
- James P White
- Dept. of Exercise Science, University of South Carolina, Public Health Research Center, Rm. 405, 921 Assembly St., Columbia, SC 29208, USA
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168
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Eisner V, Parra V, Lavandero S, Hidalgo C, Jaimovich E. Mitochondria fine-tune the slow Ca(2+) transients induced by electrical stimulation of skeletal myotubes. Cell Calcium 2010; 48:358-70. [PMID: 21106237 DOI: 10.1016/j.ceca.2010.11.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 10/25/2010] [Accepted: 11/01/2010] [Indexed: 01/22/2023]
Abstract
Mitochondria sense cytoplasmic Ca(2+) signals in many cell types. In mammalian skeletal myotubes, depolarizing stimuli induce two independent cytoplasmic Ca(2+) signals: a fast signal associated with contraction and a slow signal that propagates to the nucleus and regulates gene expression. How mitochondria sense and possibly affect these cytoplasmic Ca(2+) signals has not been reported. We investigated here (a) the emergence of mitochondrial Ca(2+) signals in response to electrical stimulation of myotubes, (b) the contribution of mitochondrial Ca(2+) transients to ATP generation and (c) the influence of mitochondria as modulators of cytoplasmic and nuclear Ca(2+) signals. Rhod2 and Fluo3 fluorescence determinations revealed composite Ca(2+) signals associated to the mitochondrial compartment in electrically stimulated (400 pulses, 45 Hz) skeletal myotubes. Similar Ca(2+) signals were detected when using a mitochondria-targeted pericam. The fast mitochondrial Ca(2+) rise induced by stimulation was inhibited by pre-incubation with ryanodine, whereas the phospholipase C inhibitor U73122 blocked the slow mitochondrial Ca(2+) signal, showing that mitochondria sense the two cytoplasmic Ca(2+) signal components. The fast but not the slow Ca(2+) transient enhanced mitochondrial ATP production. Inhibition of the mitochondrial Ca(2+) uniporter prevented the emergence of mitochondrial Ca(2+) transients and significantly increased the magnitude of slow cytoplasmic Ca(2+) signals after stimulation. Precluding mitochondrial Ca(2+) extrusion with the Na(+)/Ca(2+) exchanger inhibitor CGP37157 decreased mitochondrial potential, increased the magnitude of the slow cytoplasmic Ca(2+) signal and decreased the rate of Ca(2+) signal propagation from one nucleus to the next. Over expression of the mitochondrial fission protein Drp-1 decreased mitochondrial size and the slow Ca(2+) transient in mitochondria, but enhanced cytoplasmic and nuclear slow transients. The present results indicate that mitochondria play a central role in the regulation of Ca(2+) signals involved in gene expression in myotubes.
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Affiliation(s)
- Veronica Eisner
- Centro de Estudios Moleculares de la Celula, Universidad de Chile, Instituto de Ciencias Biomédicas, Facultad de Medicina, Santiago 8380492, Chile
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169
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Ramírez O, García A, Rojas R, Couve A, Härtel S. Confined displacement algorithm determines true and random colocalization in fluorescence microscopy. J Microsc 2010; 239:173-83. [PMID: 20701655 DOI: 10.1111/j.1365-2818.2010.03369.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The quantification of colocalizing signals in multichannel fluorescence microscopy images depends on the reliable segmentation of corresponding regions of interest, on the selection of appropriate colocalization coefficients, and on a robust statistical criterion to discriminate true from random colocalization. Here, we introduce a confined displacement algorithm based on image correlation spectroscopy in combination with Manders colocalization coefficients M1(ROI) and M2(ROI) to quantify true and random colocalization of a given florescence pattern. We show that existing algorithms based on block scrambling exaggerate the randomization of fluorescent patterns with resulting inappropriately narrow probability density functions and false significance of true colocalization in terms of p values. We further confine our approach to subcellular compartments and show that true and random colocalization can be analysed for model dendrites and for GABA(B) receptor subunits GABA(B)R1/2 in cultured hippocampal neurons. Together, we demonstrate that the confined displacement algorithm detects true colocalization of specific fluorescence patterns down to subcellular levels.
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Affiliation(s)
- O Ramírez
- Laboratory for Scientific Image Analysis (SCIAN-Lab) at the Anatomy and Developmental Biology Program, ICBM, Universidad de Chile, Santiago, Chile
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170
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Javadov S, Rajapurohitam V, Kilić A, Hunter JC, Zeidan A, Said Faruq N, Escobales N, Karmazyn M. Expression of mitochondrial fusion-fission proteins during post-infarction remodeling: the effect of NHE-1 inhibition. Basic Res Cardiol 2010; 106:99-109. [PMID: 20886221 DOI: 10.1007/s00395-010-0122-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 09/01/2010] [Accepted: 09/19/2010] [Indexed: 11/29/2022]
Abstract
Studies on the role of mitochondrial fission/fusion (MFF) proteins in the heart have been initiated recently due to their biological significance in cell metabolism. We hypothesized that the expression of MFF proteins is affected by post-infarction remodeling and in vitro cardiomyocyte hypertrophy, and serves as a target for the Na(+)/H(+) exchanger 1 (NHE-1) inhibition. Post-infarction remodeling was induced in Sprague-Dawley rats by coronary artery ligation (CAL) while in vitro hypertrophy was induced in cardiomyocytes by phenylephrine (PE). Mitochondrial fission (Fis1, DRP1) and fusion (Mfn2, OPA1) proteins were analyzed in heart homogenates and cell lysates by Western blotting. Our results showed that 12 and 18 weeks after CAL, Fis1 increased by 80% (P < 0.01) and 31% (P < 0.05), and Mfn2 was reduced by 17% (P < 0.05) and 22% (P < 0.05), respectively. OPA1 was not changed at 12 weeks, although its expression decreased by 18% (P < 0.05) with 18 weeks of ligation. MFF proteins were also affected by PE-induced hypertrophy that was dependent on mitochondrial permeability transition pore opening and oxidative stress. The NHE-1-specific inhibitor EMD-87580 (EMD) attenuated changes in the expression of MFF proteins in both the models of hypertrophy. The effect of EMD was likely mediated, at least in part, through its direct action on mitochondria since Percoll-purified mitochondria and mitoplasts have been shown to contain NHE-1. Our study provides the first evidence linking cardiac hypertrophy with MFF proteins expression that was affected by NHE-1 inhibition, thus suggesting that MFF proteins might be a target for pharmacotherapy with anti-hypertrophic drugs.
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Affiliation(s)
- Sabzali Javadov
- Department of Physiology, School of Medicine, University of Puerto Rico, San Juan, PR 00936-5067, USA.
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171
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Zheng M, Xiao RP. Role of mitofusin 2 in cardiovascular oxidative injury. J Mol Med (Berl) 2010; 88:987-91. [PMID: 20824264 DOI: 10.1007/s00109-010-0675-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 08/16/2010] [Accepted: 08/16/2010] [Indexed: 01/27/2023]
Abstract
Mitochondria are highly dynamic organelles with constant shape changes regulated by fusion and fission events. In addition to regulating mitochondrial morphology, mitochondrial fusion/fission is involved in fundamental mitochondrial biological processes, including mitochondrial metabolism, energization, respiration, mitochondrial membrane potential, and mtDNA stability. Dysfunction of mitochondrial dynamics has been implicated in various human diseases, especially in neurodegenerative diseases. Emerging evidence indicates that impaired expression of mitochondrial fusion proteins or their malfunction participates in oxidative stress-induced cardiovascular injury. This review will focus on recent advances of mitochondrial fusion in regulating various cellular processes in cardiovascular system.
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Affiliation(s)
- Ming Zheng
- Institute of Molecular Medicine, Peking University, Beijing, 100871, People's Republic of China
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172
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Abstract
Mitochondria are dynamic and are able to interchange their morphology between elongated interconnected mitochondrial networks and a fragmented disconnected arrangement by the processes of mitochondrial fusion and fission, respectively. Changes in mitochondrial morphology are regulated by the mitochondrial fusion proteins (mitofusins 1 and 2, and optic atrophy 1) and the mitochondrial fission proteins (dynamin-related peptide 1 and mitochondrial fission protein 1) and have been implicated in a variety of biological processes including embryonic development, metabolism, apoptosis, and autophagy, although the majority of studies have been largely confined to non-cardiac cells. Despite the unique arrangement of mitochondria in the adult heart, emerging data suggest that changes in mitochondrial morphology may be relevant to various aspects of cardiovascular biology-these include cardiac development, the response to ischaemia-reperfusion injury, heart failure, diabetes mellitus, and apoptosis. Interestingly, the machinery required for altering mitochondrial shape in terms of the mitochondrial fusion and fission proteins are all present in the adult heart, but their physiological function remains unclear. In this article, we review the current developments in this exciting new field of mitochondrial biology, the implications for cardiovascular physiology, and the potential for discovering novel therapeutic strategies for treating cardiovascular disease.
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Affiliation(s)
- Sang-Bing Ong
- The Hatter Cardiovascular Institute, University College, London WC1E 6HX, UK
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173
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Palaniyandi SS, Qi X, Yogalingam G, Ferreira JCB, Mochly-Rosen D. Regulation of mitochondrial processes: a target for heart failure. ACTA ACUST UNITED AC 2010; 7:e95-e102. [PMID: 21278905 DOI: 10.1016/j.ddmec.2010.07.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cardiac mitochondria, the main source of energy as well as free radicals, are vital organelles for normal functioning of the heart. Mitochondrial number, structure, turnover and function are regulated by processes such as mitochondrial protein quality control, mitochondrial fusion and fission and mitophagy. Recent studies suggest that abnormal changes in these mitochondrial regulatory processes may contribute to the pathology of heart failure (HF). Here we discuss these processes and their potential as therapeutic targets.
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174
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Mitofusin-2 protects against cold stress-induced cell injury in HEK293 cells. Biochem Biophys Res Commun 2010; 397:270-6. [PMID: 20580691 DOI: 10.1016/j.bbrc.2010.05.099] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 05/19/2010] [Indexed: 11/20/2022]
Abstract
Mitochondrial impairment is hypothesized to contribute to cell injury during cold stress. Mitochondria fission and fusion are closely related in the function of the mitochondria, but the precise mechanisms whereby these processes regulate cell injury during cold stress remain to be determined. HEK293 cells were cultured in a cold environment (4.0+/-0.1 degrees C) for 2, 4, 8, or 12h. Western blot analyses showed that these cells expressed decreased fission-related protein Drp1 and increased fusion-related protein Mfn2 at 4h; meanwhile, electron microscopy analysis revealed large and long mitochondrial morphology within these cells, indicating increased mitochondrial fusion. With silencing of Mfn2 but not of Mfn1 by siRNA promoted cold-stress-induced cell death with decreased ATP production in HEK293 cells. Our results show that increased expression of Mfn2 and mitochondrial fusion are important for mitochondrial function as well as cell survival during cold stress. These findings have important implications for understanding the mechanisms of mitochondrial fusion and fission in cold-stress-induced cell injury.
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175
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Brindley DN, Kok BPC, Kienesberger PC, Lehner R, Dyck JRB. Shedding light on the enigma of myocardial lipotoxicity: the involvement of known and putative regulators of fatty acid storage and mobilization. Am J Physiol Endocrinol Metab 2010; 298:E897-908. [PMID: 20103741 DOI: 10.1152/ajpendo.00509.2009] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Excessive fatty acid (FA) uptake by cardiac myocytes is often associated with adverse changes in cardiac function. This is especially evident in diabetic individuals, where increased intramyocardial triacylglycerol (TG) resulting from the exposure to high levels of circulating FA has been proposed to be a major contributor to diabetic cardiomyopathy. At present, our knowledge of how the heart regulates FA storage in TG and the hydrolysis of this TG is limited. This review concentrates on what is known about TG turnover within the heart and how this is likely to be regulated by extrapolating results from other tissues. We also assess the evidence as to whether increased TG accumulation protects against FA-induced lipotoxicity through limiting the accumulations of ceramides and diacylglycerols versus whether it is a maladaptive response that contributes to cardiac dysfunction.
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Affiliation(s)
- David N Brindley
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, AB, Canada.
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176
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Xu FY, McBride H, Acehan D, Vaz FM, Houtkooper RH, Lee RM, Mowat MA, Hatch GM. The dynamics of cardiolipin synthesis post-mitochondrial fusion. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1577-85. [PMID: 20434430 DOI: 10.1016/j.bbamem.2010.04.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 04/05/2010] [Accepted: 04/13/2010] [Indexed: 10/19/2022]
Abstract
Alteration in mitochondrial fusion may regulate mitochondrial metabolism. Since the phospholipid cardiolipin (CL) is required for function of the mitochondrial respiratory chain, we examined the dynamics of CL synthesis in growing Hela cells immediately after and 12h post-fusion. Cells were transiently transfected with Mfn-2, to promote fusion, or Mfn-2 expressing an inactive GTPase for 24h and de novo CL biosynthesis was examined immediately after or 12h post-fusion. Western blot analysis confirmed elevated Mfn-2 expression and electron microscopic analysis revealed that Hela cell mitochondrial structure was normal immediately after and 12h post-fusion. Cells expressing Mfn-2 exhibited reduced CL de novo biosynthesis from [1,3-(3)H]glycerol immediately after fusion and this was due to a decrease in phosphatidylglycerol phosphate synthase (PGPS) activity and its mRNA expression. In contrast, 12h post-mitochondrial fusion cells expressing Mfn-2 exhibited increased CL de novo biosynthesis from [1,3-(3)H]glycerol and this was due to an increase in PGPS activity and its mRNA expression. Cells expressing Mfn-2 with an inactive GTPase activity did not exhibit alterations in CL de novo biosynthesis immediately after or 12h post-fusion. The Mfn-2 mediated alterations in CL de novo biosynthesis were not accompanied by alterations in CL or monolysoCL mass. [1-(14)C]Oleate incorporation into CL was elevated at 12h post-fusion indicating increased CL resynthesis. The reason for the increased CL resynthesis was an increased mRNA expression of tafazzin, a mitochondrial CL resynthesis enzyme. Ceramide-induced expression of PGPS in Hela cells or in CHO cells did not alter expression of Mfn-2 indicating that Mfn-2 expression is independent of altered CL synthesis mediated by elevated PGPS. In addition, Mfn-2 expression was not altered in Hela cells expressing phospholipid scramblase-3 or a disrupted scramblase indicating that proper CL localization within mitochondria is not essential for Mfn-2 expression. The results suggest that immediately post-mitochondrial fusion CL de novo biosynthesis is "slowed down" and then 12h post-fusion it is "upregulated". The implications of this are discussed.
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Affiliation(s)
- Fred Y Xu
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Canada
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177
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Siskind LJ, Mullen TD, Romero Rosales K, Clarke CJ, Hernandez-Corbacho MJ, Edinger AL, Obeid LM. The BCL-2 protein BAK is required for long-chain ceramide generation during apoptosis. J Biol Chem 2010; 285:11818-26. [PMID: 20172858 DOI: 10.1074/jbc.m109.078121] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The BCL-2 family members BAK and BAX are required for apoptosis and trigger mitochondrial outer membrane permeabilization (MOMP). Here we identify a MOMP-independent function of BAK as a required factor for long-chain ceramide production in response to pro-apoptotic stress. UV-C irradiation of wild-type (WT) cells increased long-chain ceramides; blocking ceramide generation prevented caspase activation and cell death, demonstrating that long-chain ceramides play a key role in UV-C-induced apoptosis. In contrast, UV-C irradiation did not increase long-chain ceramides in BAK and BAX double knock-out cells. Notably, this was not specific to the cell type (baby mouse kidney cells, hematopoietic) nor the apoptotic stimulus employed (UV-C, cisplatin, and growth factor withdrawal). Importantly, long-chain ceramide generation was dependent on the presence of BAK, but not BAX. However, ceramide generation was independent of the known downstream actions of BAK in apoptosis (MOMP or caspase activation), suggesting a novel role for BAK in apoptosis. Finally, enzymatic assays identified ceramide synthase as the mechanism by which BAK regulates ceramide metabolism. There was no change in CerS expression at the message or protein level, indicating regulation at the post-translational level. Moreover, CerS activity in BAK KO microsomes can be reactivated upon addition of BAK-containing microsomes. The data presented indicate that ceramide-induced apoptosis is dependent upon BAK and identify a novel role for BAK during apoptosis. By establishing a unique role for BAK in long-chain ceramide metabolism, these studies further demonstrate that the seemingly redundant proteins BAK and BAX have distinct mechanisms of action during apoptosis induction.
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Affiliation(s)
- Leah J Siskind
- Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401, USA.
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178
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Silymarin modulates doxorubicin-induced oxidative stress, Bcl-xL and p53 expression while preventing apoptotic and necrotic cell death in the liver. Toxicol Appl Pharmacol 2010; 245:143-52. [PMID: 20144634 DOI: 10.1016/j.taap.2010.02.002] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 01/27/2010] [Accepted: 02/01/2010] [Indexed: 01/08/2023]
Abstract
The emergence of silymarin (SMN) as a natural remedy for liver diseases, coupled with its entry into NIH clinical trial, signifies its hepatoprotective potential. SMN is noted for its ability to interfere with apoptotic signaling while acting as an antioxidant. This in vivo study was designed to explore the hepatotoxic potential of Doxorubicin (Dox), the well-known cardiotoxin, and in particular whether pre-exposures to SMN can prevent hepatotoxicity by reducing Dox-induced free radical mediated oxidative stress, by modulating expression of apoptotic signaling proteins like Bcl-xL, and by minimizing liver cell death occurring by apoptosis or necrosis. Groups of male ICR mice included Control, Dox alone, SMN alone, and Dox with SMN pre/co-treatment. Control and Dox groups received saline i.p. for 14 days. SMN was administered p.o. for 14 days at 16 mg/kg/day. An approximate LD(50) dose of Dox, 60 mg/kg, was administered i.p. on day 12 to animals receiving saline or SMN. Animals were euthanized 48 h later. Dox alone induced frank liver injury (>50-fold increase in serum ALT) and oxidative stress (>20-fold increase in malondialdehyde [MDA]), as well as direct damage to DNA (>15-fold increase in DNA fragmentation). Coincident genomic damage and oxidative stress influenced genomic stability, reflected in increased PARP activity and p53 expression. Decreases in Bcl-xL protein coupled with enhanced accumulation of cytochrome c in the cytosol accompanied elevated indexes of apoptotic and necrotic cell death. Significantly, SMN exposure reduced Dox hepatotoxicity and associated apoptotic and necrotic cell death. The effects of SMN on Dox were broad, including the ability to modulate changes in both Bcl-xL and p53 expression. In animals treated with SMN, tissue Bcl-xL expression exceeded control values after Dox treatment. Taken together, these results demonstrated that SMN (i) reduced, delayed onset, or prevented toxic effects of Dox which are typically associated with hydroxyl radical production, (ii) performed as an antioxidant limiting oxidative stress, (iii) protected the integrity of the genome, and (iv) antagonized apoptotic and necrotic cell death while increasing antiapoptotic Bcl-xL protein levels and minimizing the leakage of proapoptotic cytochrome c from liver mitochondria. These observations demonstrate the protective actions of SMN in liver, and raise the possibility that such protection may extend to other organs during Dox treatment including the heart.
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179
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Alcohol dehydrogenase accentuates ethanol-induced myocardial dysfunction and mitochondrial damage in mice: role of mitochondrial death pathway. PLoS One 2010; 5:e8757. [PMID: 20090911 PMCID: PMC2807457 DOI: 10.1371/journal.pone.0008757] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 12/23/2009] [Indexed: 01/12/2023] Open
Abstract
Objectives Binge drinking and alcohol toxicity are often associated with myocardial dysfunction possibly due to accumulation of the ethanol metabolite acetaldehyde although the underlying mechanism is unknown. This study was designed to examine the impact of accelerated ethanol metabolism on myocardial contractility, mitochondrial function and apoptosis using a murine model of cardiac-specific overexpression of alcohol dehydrogenase (ADH). Methods ADH and wild-type FVB mice were acutely challenged with ethanol (3 g/kg/d, i.p.) for 3 days. Myocardial contractility, mitochondrial damage and apoptosis (death receptor and mitochondrial pathways) were examined. Results Ethanol led to reduced cardiac contractility, enlarged cardiomyocyte, mitochondrial damage and apoptosis, the effects of which were exaggerated by ADH transgene. In particular, ADH exacerbated mitochondrial dysfunction manifested as decreased mitochondrial membrane potential and accumulation of mitochondrial O2•−. Myocardium from ethanol-treated mice displayed enhanced Bax, Caspase-3 and decreased Bcl-2 expression, the effect of which with the exception of Caspase-3 was augmented by ADH. ADH accentuated ethanol-induced increase in the mitochondrial death domain components pro-caspase-9 and cytochrome C in the cytoplasm. Neither ethanol nor ADH affected the expression of ANP, total pro-caspase-9, cytosolic and total pro-caspase-8, TNF-α, Fas receptor, Fas L and cytosolic AIF. Conclusions Taken together, these data suggest that enhanced acetaldehyde production through ADH overexpression following acute ethanol exposure exacerbated ethanol-induced myocardial contractile dysfunction, cardiomyocyte enlargement, mitochondrial damage and apoptosis, indicating a pivotal role of ADH in ethanol-induced cardiac dysfunction possibly through mitochondrial death pathway of apoptosis.
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180
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The Interplay between BCL-2 Family Proteins and Mitochondrial Morphology in the Regulation of Apoptosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 687:97-114. [DOI: 10.1007/978-1-4419-6706-0_6] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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181
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Kedi X, Ming Y, Yongping W, Yi Y, Xiaoxiang Z. Free cholesterol overloading induced smooth muscle cells death and activated both ER- and mitochondrial-dependent death pathway. Atherosclerosis 2009; 207:123-30. [DOI: 10.1016/j.atherosclerosis.2009.04.019] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Revised: 04/08/2009] [Accepted: 04/11/2009] [Indexed: 01/22/2023]
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182
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Mhawi AA. Interaction of doxorubicin with the subcellular structures of the sensitive and Bcl-xL-overexpressing MCF-7 cell line: Confocal and low-energy-loss transmission electron microscopy. Micron 2009; 40:702-12. [DOI: 10.1016/j.micron.2009.05.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2009] [Revised: 05/09/2009] [Accepted: 05/09/2009] [Indexed: 10/20/2022]
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183
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Scorrano L. Opening the doors to cytochrome c: Changes in mitochondrial shape and apoptosis. Int J Biochem Cell Biol 2009; 41:1875-83. [DOI: 10.1016/j.biocel.2009.04.016] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2009] [Revised: 04/15/2009] [Accepted: 04/17/2009] [Indexed: 10/20/2022]
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184
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Abstract
A hallmark of tissue injury in various models of ischemia/reperfusion (IR) is mitochondrial dysfunction and the release of mitochondrial proapoptotic proteins leading to cell death. Although IR-induced mitochondrial injury has been extensively studied and key mitochondrial functions affected by IR are chiefly characterized, the nature of the molecule that causes loss of mitochondrial integrity and function remains obscure. It has become increasingly clear that ceramide, a membrane sphingolipid and a key mediator of cell stress responses, could play a critical role in IR-induced mitochondrial damage. Emerging data point to excessive ceramide accumulation in tissue and, specifically, in mitochondria after IR. Exogenously added to isolated mitochondria, ceramide could mimic some of the mitochondrial dysfunctions occurring in IR. The recent identification and characterization of major enzymes in ceramide synthesis is expected to contribute to the understanding of molecular mechanisms of ceramide involvement in mitochondrial damage in IR. This review will examine the experimental evidence supporting the important role of ceramide in mitochondrial dysfunction in IR to highlight potential targets for pharmacological manipulation of ceramide levels.
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185
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Mitochondrial fragmentation is involved in methamphetamine-induced cell death in rat hippocampal neural progenitor cells. PLoS One 2009; 4:e5546. [PMID: 19436752 PMCID: PMC2677674 DOI: 10.1371/journal.pone.0005546] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 04/19/2009] [Indexed: 12/28/2022] Open
Abstract
Methamphetamine (METH) induces neurodegeneration through damage and apoptosis of dopaminergic nerve terminals and striatal cells, presumably via cross-talk between the endoplasmic reticulum and mitochondria-dependent death cascades. However, the effects of METH on neural progenitor cells (NPC), an important reservoir for replacing neurons and glia during development and injury, remain elusive. Using a rat hippocampal NPC (rhNPC) culture, we characterized the METH-induced mitochondrial fragmentation, apoptosis, and its related signaling mechanism through immunocytochemistry, flow cytometry, and Western blotting. We observed that METH induced rhNPC mitochondrial fragmentation, apoptosis, and inhibited cell proliferation. The mitochondrial fission protein dynamin-related protein 1 (Drp1) and reactive oxygen species (ROS), but not calcium (Ca2+) influx, were involved in the regulation of METH-induced mitochondrial fragmentation. Furthermore, our results indicated that dysregulation of ROS contributed to the oligomerization and translocation of Drp1, resulting in mitochondrial fragmentation in rhNPC. Taken together, our data demonstrate that METH-mediated ROS generation results in the dysregulation of Drp1, which leads to mitochondrial fragmentation and subsequent apoptosis in rhNPC. This provides a potential mechanism for METH-related neurodegenerative disorders, and also provides insight into therapeutic strategies for the neurodegenerative effects of METH.
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186
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Singh MV, Kapoun A, Higgins L, Kutschke W, Thurman JM, Zhang R, Singh M, Yang J, Guan X, Lowe JS, Weiss RM, Zimmermann K, Yull FE, Blackwell TS, Mohler PJ, Anderson ME. Ca2+/calmodulin-dependent kinase II triggers cell membrane injury by inducing complement factor B gene expression in the mouse heart. J Clin Invest 2009; 119:986-96. [PMID: 19273909 DOI: 10.1172/jci35814] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 01/21/2009] [Indexed: 01/04/2023] Open
Abstract
Myocardial Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibition improves cardiac function following myocardial infarction (MI), but the CaMKII-dependent pathways that participate in myocardial stress responses are incompletely understood. To address this issue, we sought to determine the transcriptional consequences of myocardial CaMKII inhibition after MI. We performed gene expression profiling in mouse hearts with cardiomyocyte-delimited transgenic expression of either a CaMKII inhibitory peptide (AC3-I) or a scrambled control peptide (AC3-C) following MI. Of the 8,600 mRNAs examined, 156 were substantially modulated by MI, and nearly half of these showed markedly altered responses to MI with CaMKII inhibition. CaMKII inhibition substantially reduced the MI-triggered upregulation of a constellation of proinflammatory genes. We studied 1 of these proinflammatory genes, complement factor B (Cfb), in detail, because complement proteins secreted by cells other than cardiomyocytes can induce sarcolemmal injury during MI. CFB protein expression in cardiomyocytes was triggered by CaMKII activation of the NF-kappaB pathway during both MI and exposure to bacterial endotoxin. CaMKII inhibition suppressed NF-kappaB activity in vitro and in vivo and reduced Cfb expression and sarcolemmal injury. The Cfb-/- mice were partially protected from the adverse consequences of MI. Our findings demonstrate what we believe is a novel target for CaMKII in myocardial injury and suggest that CaMKII is broadly important for the genetic effects of MI in cardiomyocytes.
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Affiliation(s)
- Madhu V Singh
- Division of Cardiovascular Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA.
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187
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Hom J, Sheu SS. Morphological dynamics of mitochondria--a special emphasis on cardiac muscle cells. J Mol Cell Cardiol 2009; 46:811-20. [PMID: 19281816 DOI: 10.1016/j.yjmcc.2009.02.023] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2009] [Revised: 02/22/2009] [Accepted: 02/25/2009] [Indexed: 01/10/2023]
Abstract
Mitochondria play a critical role in cellular energy metabolism, Ca(2+) homeostasis, reactive oxygen species generation, apoptosis, aging, and development. Many recent publications have shown that a continuous balance of fusion and fission of these organelles is important in maintaining their proper function. Therefore, there is a steep correlation between the form and function of mitochondria. Many major proteins involved in mitochondrial fusion and fission have been identified in different cell types, including heart. However, the functional role of mitochondrial dynamics in the heart remains, for the most part, unexplored. In this review we will cover the recent field of mitochondrial dynamics and its physiological and pathological implications, with a particular emphasis on the experimental and theoretical basis of mitochondrial dynamics in the heart.
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Affiliation(s)
- Jennifer Hom
- Department of Pharmacology and Physiology, Mitochondrial Research and Innovation Group, University of Rochester Medical Center, Rochester, NY 14642, USA
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188
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Li Y, Yin R, Liu J, Wang P, Wu S, Luo J, Zhelyabovska O, Yang Q. Peroxisome proliferator-activated receptor delta regulates mitofusin 2 expression in the heart. J Mol Cell Cardiol 2009; 46:876-82. [PMID: 19265701 DOI: 10.1016/j.yjmcc.2009.02.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 02/14/2009] [Accepted: 02/18/2009] [Indexed: 10/21/2022]
Abstract
Mitofusin 2 (Mfn2) has been proposed as an important mitochondrial protein in maintaining mitochondrial network and bioenergetics. Mfn2 is highly expressed in the heart, but is downregulated in response to hypertrophic stimuli. However, little is known about how Mfn2's expression is regulated in cardiomyocytes. Here, we have investigated how Mfn2 expression in the heart responds to fasting condition and determined if Mfn2 is one of those PPARdelta-selective target genes that are involved in myocardial energy metabolism. Fasting for 48 h in mice led to a robust increase of Mfn2 expression in the heart. On the other hand, cardiomyocyte-restricted PPARdelta deficiency in mice led to substantially diminished cardiac expression of Mfn2 transcript and protein compared to that of controls. Fasting induced cardiac expression of Mfn2 was blunted in cardiomyocyte-restricted PPARdelta deficient hearts. Moreover, PPARdelta-selective ligand treatment in cultured cardiomyocytes induced elevated Mfn2 expression. A functional PPRE consensus sequence located at -837 to -817 bp upstream of the mouse Mfn2 promoter was identified and confirmed by Electrophoretic Mobility Shift Assays and Luciferase Promoter Reporter Assays. We conclude that Mfn2 is a PPARdelta-selective target, which may play an important role in regulating myocardial energy homeostasis.
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Affiliation(s)
- Yuquan Li
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL 35294-3360, USA
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189
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Cardiomyocyte death in doxorubicin-induced cardiotoxicity. Arch Immunol Ther Exp (Warsz) 2009; 57:435-45. [PMID: 19866340 PMCID: PMC2809808 DOI: 10.1007/s00005-009-0051-8] [Citation(s) in RCA: 292] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Accepted: 05/20/2009] [Indexed: 01/07/2023]
Abstract
Doxorubicin (DOX) is one of the most widely used and successful antitumor drugs, but its cumulative and dose-dependent cardiac toxicity has been a major concern of oncologists in cancer therapeutic practice for decades. With the increasing population of cancer survivors, there is a growing need to develop preventive strategies and effective therapies against DOX-induced cardiotoxicity, in particular late-onset cardiomyopathy. Although intensive investigations on DOX-induced cardiotoxicity have continued for decades, the underlying mechanisms responsible for DOX-induced cardiotoxicity have not been completely elucidated. A rapidly expanding body of evidence supports the notion that cardiomyocyte death by apoptosis and necrosis is a primary mechanism of DOX-induced cardiomyopathy and that other types of cell death, such as autophagy and senescence/aging, may participate in this process. This review focuses on the current understanding of the molecular mechanisms underlying DOX-induced cardiomyocyte death, including the major primary mechanism of excess production of reactive oxygen species (ROS) and other recently discovered ROS-independent mechanisms. The different sensitivities to DOX-induced cell death signals between adult and young cardiomyocytes will also be discussed.
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190
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Holland WL, Summers SA. Sphingolipids, insulin resistance, and metabolic disease: new insights from in vivo manipulation of sphingolipid metabolism. Endocr Rev 2008; 29:381-402. [PMID: 18451260 PMCID: PMC2528849 DOI: 10.1210/er.2007-0025] [Citation(s) in RCA: 428] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Obesity and dyslipidemia are risk factors for metabolic disorders including diabetes and cardiovascular disease. Sphingolipids such as ceramide and glucosylceramides, while being a relatively minor component of the lipid milieu in most tissues, may be among the most pathogenic lipids in the onset of the sequelae associated with excess adiposity. Circulating factors associated with obesity (e.g., saturated fatty acids, inflammatory cytokines) selectively induce enzymes that promote sphingolipid synthesis, and lipidomic profiling reveals relationships between tissue sphingolipid levels and certain metabolic diseases. Moreover, studies in cultured cells and isolated tissues implicate sphingolipids in certain cellular events associated with diabetes and cardiovascular disease, including insulin resistance, pancreatic beta-cell failure, cardiomyopathy, and vascular dysfunction. However, definitive evidence that sphingolipids contribute to insulin resistance, diabetes, and atherosclerosis has come only recently, as researchers have found that pharmacological inhibition or genetic ablation of enzymes controlling sphingolipid synthesis in rodents ameliorates each of these conditions. Herein we will review the role of ceramide and other sphingolipid metabolites in insulin resistance, beta-cell failure, cardiomyopathy, and vascular dysfunction, focusing on these in vivo studies that identify enzymes controlling sphingolipid metabolism as therapeutic targets for combating metabolic disease.
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Affiliation(s)
- William L Holland
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah 84132, USA
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