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Justs KA, Sempertegui S, Riboul DV, Oliva CD, Durbin RJ, Crill S, Stawarski M, Su C, Renden RB, Fily Y, Macleod GT. Mitochondrial phosphagen kinases support the volatile power demands of motor nerve terminals. J Physiol 2023; 601:5705-5732. [PMID: 37942946 PMCID: PMC10841428 DOI: 10.1113/jp284872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 10/17/2023] [Indexed: 11/10/2023] Open
Abstract
Motor neurons are the longest neurons in the body, with axon terminals separated from the soma by as much as a meter. These terminals are largely autonomous with regard to their bioenergetic metabolism and must burn energy at a high rate to sustain muscle contraction. Here, through computer simulation and drawing on previously published empirical data, we determined that motor neuron terminals in Drosophila larvae experience highly volatile power demands. It might not be surprising then, that we discovered the mitochondria in the motor neuron terminals of both Drosophila and mice to be heavily decorated with phosphagen kinases - a key element in an energy storage and buffering system well-characterized in fast-twitch muscle fibres. Knockdown of arginine kinase 1 (ArgK1) in Drosophila larval motor neurons led to several bioenergetic deficits, including mitochondrial matrix acidification and a faster decline in the cytosol ATP to ADP ratio during axon burst firing. KEY POINTS: Neurons commonly fire in bursts imposing highly volatile demands on the bioenergetic machinery that generates ATP. Using a computational approach, we built profiles of presynaptic power demand at the level of single action potentials, as well as the transition from rest to sustained activity. Phosphagen systems are known to buffer ATP levels in muscles and we demonstrate that phosphagen kinases, which support such phosphagen systems, also localize to mitochondria in motor nerve terminals of fruit flies and mice. By knocking down phosphagen kinases in fruit fly motor nerve terminals, and using fluorescent reporters of the ATP:ADP ratio, lactate, pH and Ca2+ , we demonstrate a role for phosphagen kinases in stabilizing presynaptic ATP levels. These data indicate that the maintenance of phosphagen systems in motor neurons, and not just muscle, could be a beneficial initiative in sustaining musculoskeletal health and performance.
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Affiliation(s)
- Karlis A. Justs
- Integrative Biology and Neuroscience Graduate Program, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Sergio Sempertegui
- Department of Physics, College of Science, Florida Atlantic University, Boca Raton, FL, 33431, USA
| | - Danielle V. Riboul
- Integrative Biology and Neuroscience Graduate Program, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Carlos D. Oliva
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Ryan J. Durbin
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557
| | - Sarah Crill
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Michal Stawarski
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Chenchen Su
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Robert B. Renden
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557
| | - Yaouen Fily
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Gregory T. Macleod
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
- Institute for Human Health & Disease Intervention, Florida Atlantic University, Jupiter, FL 33458, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL 33458, USA
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Richardson DA, Sritangos P, James AD, Sultan A, Bruce JIE. Metabolic regulation of calcium pumps in pancreatic cancer: role of phosphofructokinase-fructose-bisphosphatase-3 (PFKFB3). Cancer Metab 2020; 8:2. [PMID: 32266066 PMCID: PMC7114799 DOI: 10.1186/s40170-020-0210-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 01/12/2020] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND High glycolytic rate is a hallmark of cancer (Warburg effect). Glycolytic ATP is required for fuelling plasma membrane calcium ATPases (PMCAs), responsible for extrusion of cytosolic calcium, in pancreatic ductal adenocarcinoma (PDAC). Phosphofructokinase-fructose-bisphosphatase-3 (PFKFB3) is a glycolytic driver that activates key rate-limiting enzyme Phosphofructokinase-1; we investigated whether PFKFB3 is required for PMCA function in PDAC cells. METHODS PDAC cell-lines, MIA PaCa-2, BxPC-3, PANC1 and non-cancerous human pancreatic stellate cells (HPSCs) were used. Cell growth, death and metabolism were assessed using sulforhodamine-B/tetrazolium-based assays, poly-ADP-ribose-polymerase (PARP1) cleavage and seahorse XF analysis, respectively. ATP was measured using a luciferase-based assay, membrane proteins were isolated using a kit and intracellular calcium concentration and PMCA activity were measured using Fura-2 fluorescence imaging. RESULTS PFKFB3 was highly expressed in PDAC cells but not HPSCs. In MIA PaCa-2, a pool of PFKFB3 was identified at the plasma membrane. PFKFB3 inhibitor, PFK15, caused reduced cell growth and PMCA activity, leading to calcium overload and apoptosis in PDAC cells. PFK15 reduced glycolysis but had no effect on steady-state ATP concentration in MIA PaCa-2. CONCLUSIONS PFKFB3 is important for maintaining PMCA function in PDAC, independently of cytosolic ATP levels and may be involved in providing a localised ATP supply at the plasma membrane.
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Affiliation(s)
- D. A. Richardson
- Division of Cancer Sciences, School of Medical Sciences, University Of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT UK
| | - P. Sritangos
- Division of Cancer Sciences, School of Medical Sciences, University Of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT UK
| | - A. D. James
- Department of Biology, University of York, Heslington, York, UK
| | - A. Sultan
- Division of Cancer Sciences, School of Medical Sciences, University Of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT UK
| | - J. I. E. Bruce
- Division of Cancer Sciences, School of Medical Sciences, University Of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT UK
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Ramírez-Barrantes R, Córdova C, Gatica S, Rodriguez B, Lozano C, Marchant I, Echeverria C, Simon F, Olivero P. Transient Receptor Potential Vanilloid 1 Expression Mediates Capsaicin-Induced Cell Death. Front Physiol 2018; 9:682. [PMID: 29922176 PMCID: PMC5996173 DOI: 10.3389/fphys.2018.00682] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 05/16/2018] [Indexed: 12/29/2022] Open
Abstract
The transient receptor potential (TRP) ion channel family consists of a broad variety of non-selective cation channels that integrate environmental physicochemical signals for dynamic homeostatic control. Involved in a variety of cellular physiological processes, TRP channels are fundamental to the control of the cell life cycle. TRP channels from the vanilloid (TRPV) family have been directly implicated in cell death. TRPV1 is activated by pain-inducing stimuli, including inflammatory endovanilloids and pungent exovanilloids, such as capsaicin (CAP). TRPV1 activation by high doses of CAP (>10 μM) leads to necrosis, but also exhibits apoptotic characteristics. However, CAP dose-response studies are lacking in order to determine whether CAP-induced cell death occurs preferentially via necrosis or apoptosis. In addition, it is not known whether cytosolic Ca2+ and mitochondrial dysfunction participates in CAP-induced TRPV1-mediated cell death. By using TRPV1-transfected HeLa cells, we investigated the underlying mechanisms involved in CAP-induced TRPV1-mediated cell death, the dependence of CAP dose, and the participation of mitochondrial dysfunction and cytosolic Ca2+ increase. Together, our results contribute to elucidate the pathophysiological steps that follow after TRPV1 stimulation with CAP. Low concentrations of CAP (1 μM) induce cell death by a mechanism involving a TRPV1-mediated rapid and transient intracellular Ca2+ increase that stimulates plasma membrane depolarization, thereby compromising plasma membrane integrity and ultimately leading to cell death. Meanwhile, higher doses of CAP induce cell death via a TRPV1-independent mechanism, involving a slow and persistent intracellular Ca2+ increase that induces mitochondrial dysfunction, plasma membrane depolarization, plasma membrane loss of integrity, and ultimately, cell death.
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Affiliation(s)
- Ricardo Ramírez-Barrantes
- Laboratorio de Estructura y Función Celular, Escuela de Medicina, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile
| | - Claudio Córdova
- Laboratorio de Estructura y Función Celular, Escuela de Medicina, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile
| | - Sebastian Gatica
- Departamento de Ciencias Biologicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile.,Millennium Institute on Immunology and Immunotherapy, Santiago, Chile
| | - Belén Rodriguez
- Laboratorio de Estructura y Función Celular, Escuela de Medicina, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile
| | - Carlo Lozano
- Laboratorio de Estructura y Función Celular, Escuela de Medicina, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile
| | - Ivanny Marchant
- Laboratorio de Estructura y Función Celular, Escuela de Medicina, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile
| | - Cesar Echeverria
- Centro Integrativo de Biología y Química Aplicada, Universidad Bernardo O'Higgins, Santiago, Chile
| | - Felipe Simon
- Departamento de Ciencias Biologicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile.,Millennium Institute on Immunology and Immunotherapy, Santiago, Chile
| | - Pablo Olivero
- Laboratorio de Estructura y Función Celular, Escuela de Medicina, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile
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Stafford N, Wilson C, Oceandy D, Neyses L, Cartwright EJ. The Plasma Membrane Calcium ATPases and Their Role as Major New Players in Human Disease. Physiol Rev 2017; 97:1089-1125. [PMID: 28566538 DOI: 10.1152/physrev.00028.2016] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 01/20/2017] [Accepted: 01/23/2017] [Indexed: 02/07/2023] Open
Abstract
The Ca2+ extrusion function of the four mammalian isoforms of the plasma membrane calcium ATPases (PMCAs) is well established. There is also ever-increasing detail known of their roles in global and local Ca2+ homeostasis and intracellular Ca2+ signaling in a wide variety of cell types and tissues. It is becoming clear that the spatiotemporal patterns of expression of the PMCAs and the fact that their abundances and relative expression levels vary from cell type to cell type both reflect and impact on their specific functions in these cells. Over recent years it has become increasingly apparent that these genes have potentially significant roles in human health and disease, with PMCAs1-4 being associated with cardiovascular diseases, deafness, autism, ataxia, adenoma, and malarial resistance. This review will bring together evidence of the variety of tissue-specific functions of PMCAs and will highlight the roles these genes play in regulating normal physiological functions and the considerable impact the genes have on human disease.
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Affiliation(s)
- Nicholas Stafford
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Claire Wilson
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Delvac Oceandy
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Ludwig Neyses
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Elizabeth J Cartwright
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
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Abstract
The PMCA is an ATP-driven Ca2+ pump critical for the maintenance of low cytosolic calcium. The PMCA has an important but paradoxical role in cell death and survival. The PMCA can be differentially regulated by caspase/calpain cleavage. Glycolytic ATP supply may be sufficient to fuel the PMCA during metabolic stress. The ATP sensitivity of the PMCA can be regulated by acidic phospholipids.
The plasma membrane Ca2+-ATPase (PMCA) is a ubiquitously expressed, ATP-driven Ca2+ pump that is critical for maintaining low resting cytosolic Ca2+ ([Ca2+]i) in all eukaryotic cells. Since cytotoxic Ca2+ overload has such a central role in cell death, the PMCA represents an essential “linchpin” for the delicate balance between cell survival and cell death. In general, impaired PMCA activity and reduced PMCA expression leads to cytotoxic Ca2+ overload and Ca2+ dependent cell death, both apoptosis and necrosis, whereas maintenance of PMCA activity or PMCA overexpression is generally accepted as being cytoprotective. However, the PMCA has a paradoxical role in cell death depending on the cell type and cellular context. The PMCA can be differentially regulated by Ca2+-dependent proteolysis, can be maintained by a localised glycolytic ATP supply, even in the face of global ATP depletion, and can be profoundly affected by the specific phospholipid environment that it sits within the membrane. The major focus of this review is to highlight some of the controversies surrounding the paradoxical role of the PMCA in cell death and survival, challenging the conventional view of ATP-dependent regulation of the PMCA and how this might influence cell fate.
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Affiliation(s)
- Jason I E Bruce
- Division of Molecular & Clinical Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom.
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Chaabane W, User SD, El-Gazzah M, Jaksik R, Sajjadi E, Rzeszowska-Wolny J, Los MJ. Autophagy, apoptosis, mitoptosis and necrosis: interdependence between those pathways and effects on cancer. Arch Immunol Ther Exp (Warsz) 2012; 61:43-58. [PMID: 23229678 DOI: 10.1007/s00005-012-0205-y] [Citation(s) in RCA: 199] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 09/06/2012] [Indexed: 12/21/2022]
Abstract
Cell death is a fundamental ingredient of life. Thus, not surprisingly more than one form of cell death exists. Several excellent reviews on various forms of cell death have already been published but manuscripts describing interconnection and interdependence between such processes are uncommon. Here, what follows is a brief introduction on all three classical forms of cell death, followed by a more detailed insight into the role of p53, the master regulator of apoptosis, and other forms of cell death. While discussing p53 and also the role of caspases in cell death forms, we offer insight into the interplay between autophagy and apoptosis, or necrosis, where autophagy may initially serve pro-survival functions. The review moves further to present some details about less researched forms of programmed cell death, namely necroptosis, necrosis and mitoptosis. These "mixed" forms of cell death allow us to highlight the interconnected nature of cell death forms, particularly apoptosis and necrosis. The interdependence between apoptosis, autophagy and necrosis, and their significance for cancer development and treatment are also analyzed in further parts of the review. In the concluding parts, the afore-mentioned issues will be put in perspective for the development of novel anti-cancer therapies.
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Affiliation(s)
- Wiem Chaabane
- Division of Cell Biology, Department Clinical and Experimental Medicine (IKE), and Integrative Regenerative Medicine Center (IGEN), Linköping University, Cell Biology Building, Linköping, Sweden
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Takahashi K, Ohta T. Low pH enhances 2-aminoethoxydiphenyl borate-induced cell death of PC12 cells. Toxicol Lett 2012; 215:161-6. [DOI: 10.1016/j.toxlet.2012.10.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 10/17/2012] [Accepted: 10/18/2012] [Indexed: 11/15/2022]
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Biology of mitochondria in neurodegenerative diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 107:355-415. [PMID: 22482456 DOI: 10.1016/b978-0-12-385883-2.00005-9] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) are the most common human adult-onset neurodegenerative diseases. They are characterized by prominent age-related neurodegeneration in selectively vulnerable neural systems. Some forms of AD, PD, and ALS are inherited, and genes causing these diseases have been identified. Nevertheless, the mechanisms of the neuronal degeneration in these familial diseases, and in the more common idiopathic (sporadic) diseases, are unresolved. Genetic, biochemical, and morphological analyses of human AD, PD, and ALS, as well as their cell and animal models, reveal that mitochondria could have roles in this neurodegeneration. The varied functions and properties of mitochondria might render subsets of selectively vulnerable neurons intrinsically susceptible to cellular aging and stress and the overlying genetic variations. In AD, alterations in enzymes involved in oxidative phosphorylation, oxidative damage, and mitochondrial binding of Aβ and amyloid precursor protein have been reported. In PD, mutations in mitochondrial proteins have been identified and mitochondrial DNA mutations have been found in neurons in the substantia nigra. In ALS, changes occur in mitochondrial respiratory chain enzymes and mitochondrial programmed cell death proteins. Transgenic mouse models of human neurodegenerative disease are beginning to reveal possible principles governing the biology of selective neuronal vulnerability that implicate mitochondria and the mitochondrial permeability transition pore. This chapter reviews several aspects of mitochondrial biology and how mitochondrial pathobiology might contribute to the mechanisms of neurodegeneration in AD, PD, and ALS.
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Pessayre D, Fromenty B, Berson A, Robin MA, Lettéron P, Moreau R, Mansouri A. Central role of mitochondria in drug-induced liver injury. Drug Metab Rev 2011; 44:34-87. [PMID: 21892896 DOI: 10.3109/03602532.2011.604086] [Citation(s) in RCA: 182] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A frequent mechanism for drug-induced liver injury (DILI) is the formation of reactive metabolites that trigger hepatitis through direct toxicity or immune reactions. Both events cause mitochondrial membrane disruption. Genetic or acquired factors predispose to metabolite-mediated hepatitis by increasing the formation of the reactive metabolite, decreasing its detoxification, or by the presence of critical human leukocyte antigen molecule(s). In other instances, the parent drug itself triggers mitochondrial membrane disruption or inhibits mitochondrial function through different mechanisms. Drugs can sequester coenzyme A or can inhibit mitochondrial β-oxidation enzymes, the transfer of electrons along the respiratory chain, or adenosine triphosphate (ATP) synthase. Drugs can also destroy mitochondrial DNA, inhibit its replication, decrease mitochondrial transcripts, or hamper mitochondrial protein synthesis. Quite often, a single drug has many different effects on mitochondrial function. A severe impairment of oxidative phosphorylation decreases hepatic ATP, leading to cell dysfunction or necrosis; it can also secondarily inhibit ß-oxidation, thus causing steatosis, and can also inhibit pyruvate catabolism, leading to lactic acidosis. A severe impairment of β-oxidation can cause a fatty liver; further, decreased gluconeogenesis and increased utilization of glucose to compensate for the inability to oxidize fatty acids, together with the mitochondrial toxicity of accumulated free fatty acids and lipid peroxidation products, may impair energy production, possibly leading to coma and death. Susceptibility to parent drug-mediated mitochondrial dysfunction can be increased by factors impairing the removal of the toxic parent compound or by the presence of other medical condition(s) impairing mitochondrial function. New drug molecules should be screened for possible mitochondrial effects.
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Affiliation(s)
- Dominique Pessayre
- INSERM, U, Centre de Recherche Bichat Beaujon CRB, Faculté de Médecine Xavier-Bichat, Paris, France.
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Gouriou Y, Demaurex N, Bijlenga P, De Marchi U. Mitochondrial calcium handling during ischemia-induced cell death in neurons. Biochimie 2011; 93:2060-7. [PMID: 21846486 DOI: 10.1016/j.biochi.2011.08.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 08/03/2011] [Indexed: 12/18/2022]
Abstract
Mitochondria sense and shape cytosolic Ca(2+) signals by taking up and subsequently releasing Ca(2+) ions during physiological and pathological Ca(2+) elevations. Sustained elevations in the mitochondrial matrix Ca(2+) concentration are increasingly recognized as a defining feature of the intracellular cascade of lethal events that occur in neurons during cerebral ischemia. Here, we review the recently identified transport proteins that mediate the fluxes of Ca(2+) across mitochondria and discuss the implication of the permeability transition pore in decoding the abnormally sustained mitochondrial Ca(2+) elevations that occur during cerebral ischemia.
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Affiliation(s)
- Yves Gouriou
- Department of Cell Physiology and Metabolism, University of Geneva, rue Michel-Servet 1, Genève, Switzerland
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Schalper KA, Sánchez HA, Lee SC, Altenberg GA, Nathanson MH, Sáez JC. Connexin 43 hemichannels mediate the Ca2+ influx induced by extracellular alkalinization. Am J Physiol Cell Physiol 2010; 299:C1504-15. [PMID: 20881238 DOI: 10.1152/ajpcell.00015.2010] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Although alkaline pH is known to trigger Ca(2+) influx in diverse cells, no pH-sensitive Ca(2+) channel has been identified. Here, we report that extracellular alkalinization induces opening of connexin 43 hemichannels (Cx43 HCs). Increasing extracellular pH from 7.4 to 8.5, in the presence of physiological Ca(2+)/Mg(2+) concentrations, rapidly increased the ethidium uptake rate and open probability of HCs in Cx43 and Cx43EGFP HeLa transfectants (HeLa-Cx3 and HeLa-Cx43EGFP, respectively) but not in parental HeLa cells (HeLa-parental) lacking Cx43 HCs. The increase in ethidium uptake induced by pH 8.5 was not affected by raising the extracellular Ca(2+) concentration from 1.8 to 10 mM but was inhibited by a connexin HC inhibitor (La(3+)). Probenecid, a pannexin HC blocker, had no effect. Extracellular alkalinization increased the intracellular Ca(2+) levels only in cells expressing HCs. The above changes induced by extracellular alkalinization did not change the cellular distribution of Cx43, suggesting that HC activation occurs through a gating mechanism. Experiments on cells expressing a COOH-terminal truncated Cx43 mutant indicated that the effects of alkalinization on intracellular Ca(2+) and ethidium uptake did not depend on the Cx43 C terminus. Moreover, purified dephosphorylated Cx43 HCs reconstituted in liposomes were Ca(2+) permeable, suggesting that Ca(2+) influx through Cx43 HCs could account for the elevation in intracellular Ca(2+) elicited by extracellular alkalinization. These studies identify a membrane pathway for Ca(2+) influx and provide a potential explanation for the activation of cellular events induced by extracellular alkalinization.
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Affiliation(s)
- Kurt A Schalper
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Alameda 340, 4 to Piso, Santiago, 8331150 Chile.
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Bruce JI. Plasma membrane calcium pump regulation by metabolic stress. World J Biol Chem 2010; 1:221-8. [PMID: 21537477 PMCID: PMC3083969 DOI: 10.4331/wjbc.v1.i7.221] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Revised: 06/30/2010] [Accepted: 07/07/2010] [Indexed: 02/05/2023] Open
Abstract
The plasma membrane Ca2+-ATPase (PMCA) is an ATP-driven pump that is critical for the maintenance of low resting [Ca2+]i in all eukaryotic cells. Metabolic stress, either due to inhibition of mitochondrial or glycolytic metabolism, has the capacity to cause ATP depletion and thus inhibit PMCA activity. This has potentially fatal consequences, particularly for non-excitable cells in which the PMCA is the major Ca2+ efflux pathway. This is because inhibition of the PMCA inevitably leads to cytosolic Ca2+ overload and the consequent cell death. However, the relationship between metabolic stress, ATP depletion and inhibition of the PMCA is not as simple as one would have originally predicted. There is increasing evidence that metabolic stress can lead to the inhibition of PMCA activity independent of ATP or prior to substantial ATP depletion. In particular, there is evidence that the PMCA has its own glycolytic ATP supply that can fuel the PMCA in the face of impaired mitochondrial function. Moreover, membrane phospholipids, mitochondrial membrane potential, caspase/calpain cleavage and oxidative stress have all been implicated in metabolic stress-induced inhibition of the PMCA. The major focus of this review is to challenge the conventional view of ATP-dependent regulation of the PMCA and bring together some of the alternative or additional mechanisms by which metabolic stress impairs PMCA activity resulting in cytosolic Ca2+ overload and cytotoxicity.
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Affiliation(s)
- Jason Ie Bruce
- Jason IE Bruce, Faculty of Life Sciences, The University of Manchester, Manchester M13 9NT, United Kingdom
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13
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Abstract
Alzheimer’s disease (AD), Parkinson’s disease (PD) and amyotrophic lateral sclerosis (ALS) are the most common human adult-onset neurodegenerative diseases. They are characterized by prominent age-related neurodegeneration in selectively vulnerable neural systems. Some forms of AD, PD, and ALS are inherited, and genes causing these diseases have been identified. Nevertheless, the mechanisms of the neuronal cell death are unresolved. Morphological, biochemical, genetic, as well as cell and animal model studies reveal that mitochondria could have roles in this neurodegeneration. The functions and properties of mitochondria might render subsets of selectively vulnerable neurons intrinsically susceptible to cellular aging and stress and overlying genetic variations, triggering neurodegeneration according to a cell death matrix theory. In AD, alterations in enzymes involved in oxidative phosphorylation, oxidative damage, and mitochondrial binding of Aβ and amyloid precursor protein have been reported. In PD, mutations in putative mitochondrial proteins have been identified and mitochondrial DNA mutations have been found in neurons in the substantia nigra. In ALS, changes occur in mitochondrial respiratory chain enzymes and mitochondrial cell death proteins. Transgenic mouse models of human neurodegenerative disease are beginning to reveal possible principles governing the biology of selective neuronal vulnerability that implicate mitochondria and the mitochondrial permeability transition pore. This review summarizes how mitochondrial pathobiology might contribute to neuronal death in AD, PD, and ALS and could serve as a target for drug therapy.
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Baggaley EM, Elliott AC, Bruce JIE. Oxidant-induced inhibition of the plasma membrane Ca2+-ATPase in pancreatic acinar cells: role of the mitochondria. Am J Physiol Cell Physiol 2008; 295:C1247-60. [PMID: 18787078 DOI: 10.1152/ajpcell.00083.2008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Impairment of the normal spatiotemporal pattern of intracellular Ca(2+) ([Ca(2+)](i)) signaling, and in particular, the transition to an irreversible "Ca(2+) overload" response, has been implicated in various pathophysiological states. In some diseases, including pancreatitis, oxidative stress has been suggested to mediate this Ca(2+) overload and the associated cell injury. We have previously demonstrated that oxidative stress with hydrogen peroxide (H(2)O(2)) evokes a Ca(2+) overload response and inhibition of plasma membrane Ca(2+)-ATPase (PMCA) in rat pancreatic acinar cells (Bruce JI and Elliott AC. Am J Physiol Cell Physiol 293: C938-C950, 2007). The aim of the present study was to further examine this oxidant-impaired inhibition of the PMCA, focusing on the role of the mitochondria. Using a [Ca(2+)](i) clearance assay in which mitochondrial Ca(2+) uptake was blocked with Ru-360, H(2)O(2) (50 microM-1 mM) markedly inhibited the PMCA activity. This H(2)O(2)-induced inhibition of the PMCA correlated with mitochondrial depolarization (assessed using tetramethylrhodamine methylester fluorescence) but could occur without significant ATP depletion (assessed using Magnesium Green fluorescence). The H(2)O(2)-induced PMCA inhibition was sensitive to the mitochondrial permeability transition pore (mPTP) inhibitors, cyclosporin-A and bongkrekic acid. These data suggest that oxidant-induced opening of the mPTP and mitochondrial depolarization may lead to an inhibition of the PMCA that is independent of mitochondrial Ca(2+) handling and ATP depletion, and we speculate that this may involve the release of a mitochondrial factor. Such a phenomenon may be responsible for the Ca(2+) overload response, and for the transition between apoptotic and necrotic cell death thought to be important in many disease states.
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Affiliation(s)
- Erin M Baggaley
- Faculty of Life Sciences, 2nd Floor Core Technology Facility, 46 Grafton St., Univ. of Manchester, Manchester M13 9NT, UK
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15
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Secondary necrosis in multicellular animals: an outcome of apoptosis with pathogenic implications. Apoptosis 2008; 13:463-82. [PMID: 18322800 PMCID: PMC7102248 DOI: 10.1007/s10495-008-0187-8] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 02/14/2008] [Indexed: 01/11/2023]
Abstract
In metazoans apoptosis is a major physiological process of cell elimination during development and in tissue homeostasis and can be involved in pathological situations. In vitro, apoptosis proceeds through an execution phase during which cell dismantling is initiated, with or without fragmentation into apoptotic bodies, but with maintenance of a near-to-intact cytoplasmic membrane, followed by a transition to a necrotic cell elimination traditionally called “secondary necrosis”. Secondary necrosis involves activation of self-hydrolytic enzymes, and swelling of the cell or of the apoptotic bodies, generalized and irreparable damage to the cytoplasmic membrane, and culminates with cell disruption. In vivo, under normal conditions, the elimination of apoptosing cells or apoptotic bodies is by removal through engulfment by scavengers prompted by the exposure of engulfment signals during the execution phase of apoptosis; if this removal fails progression to secondary necrosis ensues as in the in vitro situation. In vivo secondary necrosis occurs when massive apoptosis overwhelms the available scavenging capacity, or when the scavenger mechanism is directly impaired, and may result in leakage of the cell contents with induction of tissue injury and inflammatory and autoimmune responses. Several disorders where secondary necrosis has been implicated as a pathogenic mechanism will be reviewed.
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Mongin AA. Disruption of ionic and cell volume homeostasis in cerebral ischemia: The perfect storm. ACTA ACUST UNITED AC 2007; 14:183-93. [PMID: 17961999 DOI: 10.1016/j.pathophys.2007.09.009] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The mechanisms of brain tissue damage in stroke are strongly linked to the phenomenon of excitotoxicity, which is defined as damage or death of neural cells due to excessive activation of receptors for the excitatory neurotransmitters glutamate and aspartate. Under physiological conditions, ionotropic glutamate receptors mediate the processes of excitatory neurotransmission and synaptic plasticity. In ischemia, sustained pathological release of glutamate from neurons and glial cells causes prolonged activation of these receptors, resulting in massive depolarization and cytoplasmic Ca(2+) overload. High cytoplasmic levels of Ca(2+) activate many degradative processes that, depending on the metabolic status, cause immediate or delayed death of neural cells. This traditional view has been expanded by a number of observations that implicate Cl(-) channels and several types of non-channel transporter proteins, such as the Na(+),K(+),2Cl(-) cotransporter, Na(+)/H(+) exchanger, and Na(+)/Ca(2+) exchanger, in the development of glutamate toxicity. Some of these ion transporters increase tissue damage by promoting pathological cell swelling and necrotic cell death, while others contribute to a long-term accumulation of cytoplasmic Ca(2+). This brief review is aimed at illustrating how the dysregulation of various ion transport processes combine in a 'perfect storm' that disrupts neural ionic homeostasis and culminates in the irreversible damage and death of neural cells. The clinical relevance of individual transporters as targets for therapeutic intervention in stroke is also briefly discussed.
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Affiliation(s)
- Alexander A Mongin
- Center for Neuropharmacology and Neuroscience, Albany Medical College, 47 New Scotland Avenue (MC-136), Albany, NY 12208, USA
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