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Balderas E, Lee SHJ, Rai NK, Mollinedo DM, Duron HE, Chaudhuri D. Mitochondrial Calcium Regulation of Cardiac Metabolism in Health and Disease. Physiology (Bethesda) 2024; 39:0. [PMID: 38713090 DOI: 10.1152/physiol.00014.2024] [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: 02/29/2024] [Revised: 05/02/2024] [Accepted: 05/02/2024] [Indexed: 05/08/2024] Open
Abstract
Oxidative phosphorylation is regulated by mitochondrial calcium (Ca2+) in health and disease. In physiological states, Ca2+ enters via the mitochondrial Ca2+ uniporter and rapidly enhances NADH and ATP production. However, maintaining Ca2+ homeostasis is critical: insufficient Ca2+ impairs stress adaptation, and Ca2+ overload can trigger cell death. In this review, we delve into recent insights further defining the relationship between mitochondrial Ca2+ dynamics and oxidative phosphorylation. Our focus is on how such regulation affects cardiac function in health and disease, including heart failure, ischemia-reperfusion, arrhythmias, catecholaminergic polymorphic ventricular tachycardia, mitochondrial cardiomyopathies, Barth syndrome, and Friedreich's ataxia. Several themes emerge from recent data. First, mitochondrial Ca2+ regulation is critical for fuel substrate selection, metabolite import, and matching of ATP supply to demand. Second, mitochondrial Ca2+ regulates both the production and response to reactive oxygen species (ROS), and the balance between its pro- and antioxidant effects is key to how it contributes to physiological and pathological states. Third, Ca2+ exerts localized effects on the electron transport chain (ETC), not through traditional allosteric mechanisms but rather indirectly. These effects hinge on specific transporters, such as the uniporter or the Na+/Ca2+ exchanger, and may not be noticeable acutely, contributing differently to phenotypes depending on whether Ca2+ transporters are acutely or chronically modified. Perturbations in these novel relationships during disease states may either serve as compensatory mechanisms or exacerbate impairments in oxidative phosphorylation. Consequently, targeting mitochondrial Ca2+ holds promise as a therapeutic strategy for a variety of cardiac diseases characterized by contractile failure or arrhythmias.
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Affiliation(s)
- Enrique Balderas
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
| | - Sandra H J Lee
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
| | - Neeraj K Rai
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
| | - David M Mollinedo
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
| | - Hannah E Duron
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
| | - Dipayan Chaudhuri
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States
- Division of Cardiovascular Medicine, Department of Internal Medicine, Biochemistry, Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States
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Nasuhidehnavi A, Zarzycka W, Górecki I, Chiao YA, Lee CF. Emerging interactions between mitochondria and NAD + metabolism in cardiometabolic diseases. Trends Endocrinol Metab 2024:S1043-2760(24)00191-7. [PMID: 39198117 DOI: 10.1016/j.tem.2024.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 07/12/2024] [Accepted: 07/15/2024] [Indexed: 09/01/2024]
Abstract
Nicotinamide adenine dinucleotide (NAD+) is an essential coenzyme for redox reactions and regulates cellular catabolic pathways. An intertwined relationship exists between NAD+ and mitochondria, with consequences for mitochondrial function. Dysregulation in NAD+ homeostasis can lead to impaired energetics and increased oxidative stress, contributing to the pathogenesis of cardiometabolic diseases. In this review, we explore how disruptions in NAD+ homeostasis impact mitochondrial function in various cardiometabolic diseases. We discuss emerging studies demonstrating that enhancing NAD+ synthesis or inhibiting its consumption can ameliorate complications of this family of pathological conditions. Additionally, we highlight the potential role and therapeutic promise of mitochondrial NAD+ transporters in regulating cellular and mitochondrial NAD+ homeostasis.
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Affiliation(s)
- Azadeh Nasuhidehnavi
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA; Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Binghamton University, Binghamton, NY 13790, USA
| | - Weronika Zarzycka
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA; Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Ignacy Górecki
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Ying Ann Chiao
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA; Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Chi Fung Lee
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA; Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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de Zélicourt A, Fayssoil A, Mansart A, Zarrouki F, Karoui A, Piquereau J, Lefebvre F, Gerbaud P, Mika D, Dakouane-Giudicelli M, Lanchec E, Feng M, Leblais V, Bobe R, Launay JM, Galione A, Gomez AM, de la Porte S, Cancela JM. Two-pore channels (TPCs) acts as a hub for excitation-contraction coupling, metabolism and cardiac hypertrophy signalling. Cell Calcium 2024; 117:102839. [PMID: 38134531 DOI: 10.1016/j.ceca.2023.102839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/01/2023] [Accepted: 12/02/2023] [Indexed: 12/24/2023]
Abstract
Ca2+ signaling is essential for cardiac contractility and excitability in heart function and remodeling. Intriguingly, little is known about the role of a new family of ion channels, the endo-lysosomal non-selective cation "two-pore channel" (TPCs) in heart function. Here we have used double TPC knock-out mice for the 1 and 2 isoforms of TPCs (Tpcn1/2-/-) and evaluated their cardiac function. Doppler-echocardiography unveils altered left ventricular (LV) systolic function associated with a LV relaxation impairment. In cardiomyocytes isolated from Tpcn1/2-/- mice, we observed a reduction in the contractile function with a decrease in the sarcoplasmic reticulum Ca2+ content and a reduced expression of various key proteins regulating Ca2+ stores, such as calsequestrin. We also found that two main regulators of the energy metabolism, AMP-activated protein kinase and mTOR, were down regulated. We found an increase in the expression of TPC1 and TPC2 in a model of transverse aortic constriction (TAC) mice and in chronically isoproterenol infused WT mice. In this last model, adaptive cardiac hypertrophy was reduced by Tpcn1/2 deletion. Here, we propose a central role for TPCs and lysosomes that could act as a hub integrating information from the excitation-contraction coupling mechanisms, cellular energy metabolism and hypertrophy signaling.
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Affiliation(s)
- Antoine de Zélicourt
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, 78000 Versailles, France; Neuroscience Paris-Saclay Institute (Neuro-PSI), UMR 9197, CNRS- Université Paris-Saclay, Saclay, 91400, France
| | - Abdallah Fayssoil
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, 78000 Versailles, France
| | - Arnaud Mansart
- Université Paris-Saclay, UVSQ, Inserm, 2I, 78000 Versailles, France
| | - Faouzi Zarrouki
- Neuroscience Paris-Saclay Institute (Neuro-PSI), UMR 9197, CNRS- Université Paris-Saclay, Saclay, 91400, France
| | - Ahmed Karoui
- UMR-S 1180, INSERM, Signaling and cardiovascular pathophysiology, Université Paris-Saclay, 91400 Orsay, France
| | - Jérome Piquereau
- UMR-S 1180, INSERM, Signaling and cardiovascular pathophysiology, Université Paris-Saclay, 91400 Orsay, France
| | - Florence Lefebvre
- UMR-S 1180, INSERM, Signaling and cardiovascular pathophysiology, Université Paris-Saclay, 91400 Orsay, France
| | - Pascale Gerbaud
- UMR-S 1180, INSERM, Signaling and cardiovascular pathophysiology, Université Paris-Saclay, 91400 Orsay, France
| | - Delphine Mika
- UMR-S 1180, INSERM, Signaling and cardiovascular pathophysiology, Université Paris-Saclay, 91400 Orsay, France
| | | | - Erwan Lanchec
- Neuroscience Paris-Saclay Institute (Neuro-PSI), UMR 9197, CNRS- Université Paris-Saclay, Saclay, 91400, France
| | - Miao Feng
- UMR-S 1176, Université Paris-Saclay, Le Kremlin Bicêtre, France
| | - Véronique Leblais
- UMR-S 1180, INSERM, Signaling and cardiovascular pathophysiology, Université Paris-Saclay, 91400 Orsay, France
| | - Régis Bobe
- UMR-S 1176, Université Paris-Saclay, Le Kremlin Bicêtre, France
| | - Jean-Marie Launay
- Service de Biochimie, INSERM UMR S942, Hôpital Lariboisière, Paris, France
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom
| | - Ana Maria Gomez
- UMR-S 1180, INSERM, Signaling and cardiovascular pathophysiology, Université Paris-Saclay, 91400 Orsay, France
| | - Sabine de la Porte
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, 78000 Versailles, France
| | - José-Manuel Cancela
- Neuroscience Paris-Saclay Institute (Neuro-PSI), UMR 9197, CNRS- Université Paris-Saclay, Saclay, 91400, France.
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Chintaluri C, Vogels TP. Metabolically regulated spiking could serve neuronal energy homeostasis and protect from reactive oxygen species. Proc Natl Acad Sci U S A 2023; 120:e2306525120. [PMID: 37988463 PMCID: PMC10691349 DOI: 10.1073/pnas.2306525120] [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: 05/11/2023] [Accepted: 10/11/2023] [Indexed: 11/23/2023] Open
Abstract
So-called spontaneous activity is a central hallmark of most nervous systems. Such non-causal firing is contrary to the tenet of spikes as a means of communication, and its purpose remains unclear. We propose that self-initiated firing can serve as a release valve to protect neurons from the toxic conditions arising in mitochondria from lower-than-baseline energy consumption. To demonstrate the viability of our hypothesis, we built a set of models that incorporate recent experimental results indicating homeostatic control of metabolic products-Adenosine triphosphate (ATP), adenosine diphosphate (ADP), and reactive oxygen species (ROS)-by changes in firing. We explore the relationship of metabolic cost of spiking with its effect on the temporal patterning of spikes and reproduce experimentally observed changes in intrinsic firing in the fruitfly dorsal fan-shaped body neuron in a model with ROS-modulated potassium channels. We also show that metabolic spiking homeostasis can produce indefinitely sustained avalanche dynamics in cortical circuits. Our theory can account for key features of neuronal activity observed in many studies ranging from ion channel function all the way to resting state dynamics. We finish with a set of experimental predictions that would confirm an integrated, crucial role for metabolically regulated spiking and firmly link metabolic homeostasis and neuronal function.
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Affiliation(s)
- Chaitanya Chintaluri
- Institute of Science and Technology Austria, KlosterneuburgA-3400, Austria
- Centre for Neural Circuits and Behaviour, Department of Physiology, Anatomy and Genetics, University of Oxford, OxfordOX13SR, United Kingdom
| | - Tim P. Vogels
- Institute of Science and Technology Austria, KlosterneuburgA-3400, Austria
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Lee SH, Duron HE, Chaudhuri D. Beyond the TCA cycle: new insights into mitochondrial calcium regulation of oxidative phosphorylation. Biochem Soc Trans 2023; 51:1661-1673. [PMID: 37641565 PMCID: PMC10508640 DOI: 10.1042/bst20230012] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/10/2023] [Accepted: 08/16/2023] [Indexed: 08/31/2023]
Abstract
While mitochondria oxidative phosphorylation is broadly regulated, the impact of mitochondrial Ca2+ on substrate flux under both physiological and pathological conditions is increasingly being recognized. Under physiologic conditions, mitochondrial Ca2+ enters through the mitochondrial Ca2+ uniporter and boosts ATP production. However, maintaining Ca2+ homeostasis is crucial as too little Ca2+ inhibits adaptation to stress and Ca2+ overload can trigger cell death. In this review, we discuss new insights obtained over the past several years expanding the relationship between mitochondrial Ca2+ and oxidative phosphorylation, with most data obtained from heart, liver, or skeletal muscle. Two new themes are emerging. First, beyond boosting ATP synthesis, Ca2+ appears to be a critical determinant of fuel substrate choice between glucose and fatty acids. Second, Ca2+ exerts local effects on the electron transport chain indirectly, not via traditional allosteric mechanisms. These depend critically on the transporters involved, such as the uniporter or the Na+-Ca2+ exchanger. Alteration of these new relationships during disease can be either compensatory or harmful and suggest that targeting mitochondrial Ca2+ may be of therapeutic benefit during diseases featuring impairments in oxidative phosphorylation.
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Affiliation(s)
- Sandra H. Lee
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA
| | - Hannah E. Duron
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA
| | - Dipayan Chaudhuri
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA
- Division of Cardiovascular Medicine, Department of Internal Medicine, Biochemistry, Biomedical Engineering, University of Utah, Salt Lake City, Utah, USA
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Yip KP, Ribeiro-Silva L, Cha B, Rieg T, Sham JSK. Epac induces ryanodine receptor-dependent intracellular and inter-organellar calcium mobilization in mpkCCD cells. Front Physiol 2023; 14:1250273. [PMID: 37711462 PMCID: PMC10497751 DOI: 10.3389/fphys.2023.1250273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 08/11/2023] [Indexed: 09/16/2023] Open
Abstract
Arginine vasopressin (AVP) induces an increase in intracellular Ca2+ concentration ([Ca2+]i) with an oscillatory pattern in isolated perfused kidney inner medullary collecting duct (IMCD). The AVP-induced Ca2+ mobilization in inner medullary collecting ducts is essential for apical exocytosis and is mediated by the exchange protein directly activated by cyclic adenosine monophosphate (Epac). Murine principal kidney cortical collecting duct cells (mpkCCD) is the cell model used for transcriptomic and phosphoproteomic studies of AVP signaling in kidney collecting duct. The present study examined the characteristics of Ca2+ mobilization in mpkCCD cells, and utilized mpkCCD as a model to investigate the Epac-induced intracellular and intra-organellar Ca2+ mobilization. Ca2+ mobilization in cytosol, endoplasmic reticulum lumen, and mitochondrial matrix were monitored with a Ca2+ sensitive fluorescent probe and site-specific Ca2+ sensitive biosensors. Fluorescence images of mpkCCD cells and isolated perfused inner medullary duct were collected with confocal microscopy. Cell permeant ligands of ryanodine receptors (RyRs) and inositol 1,4,5 trisphosphate receptors (IP3Rs) both triggered increase of [Ca2+]i and Ca2+ oscillations in mpkCCD cells as reported previously in IMCD. The cell permeant Epac-specific cAMP analog Me-cAMP/AM also caused a robust Ca2+ mobilization and oscillations in mpkCCD cells. Using biosensors to monitor endoplasmic reticulum (ER) luminal Ca2+ and mitochondrial matrix Ca2+, Me-cAMP/AM not only triggered Ca2+ release from ER into cytoplasm, but also shuttled Ca2+ from ER into mitochondria. The Epac-agonist induced synchronized Ca2+ spikes in cytosol and mitochondrial matrix, with concomitant declines in ER luminal Ca2+. Me-cAMP/AM also effectively triggered store-operated Ca2+ entry (SOCE), suggesting that Epac-agonist is capable of depleting ER Ca2+ stores. These Epac-induced intracellular and inter-organelle Ca2+ signals were mimicked by the RyR agonist 4-CMC, but they were distinctly different from IP3R activation. The present study hence demonstrated that mpkCCD cells retain all reported features of Ca2+ mobilization observed in isolated perfused IMCD. It further revealed information on the dynamics of Epac-induced RyR-dependent Ca2+ signaling and ER-mitochondrial Ca2+ transfer. ER-mitochondrial Ca2+ coupling may play a key role in the regulation of ATP and reactive oxygen species (ROS) production in the mitochondria along the nephron. Our data suggest that mpkCCD cells can serve as a renal cell model to address novel questions of how mitochondrial Ca2+ regulates cytosolic Ca2+ signals, inter-organellar Ca2+ signaling, and renal tubular functions.
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Affiliation(s)
- Kay-Pong Yip
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
- Hypertension and Kidney Research Center, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Luisa Ribeiro-Silva
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Byeong Cha
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Timo Rieg
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
- Hypertension and Kidney Research Center, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
- James A. Haley Veterans’ Hospital, Tampa, FL, United States
| | - James S. K. Sham
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Keidar N, Peretz NK, Yaniv Y. Ca 2+ pushes and pulls energetics to maintain ATP balance in atrial cells: computational insights. Front Physiol 2023; 14:1231259. [PMID: 37528893 PMCID: PMC10387757 DOI: 10.3389/fphys.2023.1231259] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 07/03/2023] [Indexed: 08/03/2023] Open
Abstract
To maintain atrial function, ATP supply-to-demand matching must be tightly controlled. Ca2+ can modulate both energy consumption and production. In light of evidence suggesting that Ca2+ affects energetics through "push" (activating metabolite flux and enzymes in the Krebs cycle to push the redox flux) and "pull" (acting directly on ATP synthase and driving the redox flux through the electron transport chain and increasing ATP production) pathways, we investigated whether both pathways are necessary to maintain atrial ATP supply-to-demand matching. Rabbit right atrial cells were electrically stimulated at different rates, and oxygen consumption and flavoprotein fluorescence were measured. To gain mechanistic insight into the regulators of ATP supply-to-demand matching in atrial cells, models of atrial electrophysiology, Ca2+ cycling and force were integrated with a model of mitochondrial Ca2+ and a modified model of mitochondrial energy metabolism. The experimental results showed that oxygen consumption increased in response to increases in the electrical stimulation rate. The model reproduced these findings and predicted that the increase in oxygen consumption is associated with metabolic homeostasis. The model predicted that Ca2+ must act both in "push" and "pull" pathways to increase oxygen consumption. In contrast to ventricular trabeculae, no rapid time-dependent changes in mitochondrial flavoprotein fluorescence were measured upon an abrupt change in workload. The model reproduced these findings and predicted that the maintenance of metabolic homeostasis is due to the effects of Ca2+ on ATP production. Taken together, this work provides evidence of Ca2+ "push" and "pull" activity to maintain metabolic homeostasis in atrial cells.
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Kim Y, Ajayi PT, Bleck CKE, Glancy B. Three-dimensional remodelling of the cellular energy distribution system during postnatal heart development. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210322. [PMID: 36189814 PMCID: PMC9527916 DOI: 10.1098/rstb.2021.0322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/11/2022] [Indexed: 11/12/2022] Open
Abstract
The heart meets the high energy demands of constant muscle contraction and calcium cycling primarily through the conversion of fatty acids into adenosine triphosphate (ATP) by a large volume of mitochondria. As such, the spatial relationships among lipid droplets (LDs), mitochondria, the sarcotubular system and the contractile apparatus are critical to the efficient distribution of energy within the cardiomyocyte. However, the connectivity among components of the cardiac cellular energy distribution system during postnatal development remains unclear. Here, we use volume electron microscopy to demonstrate that the sarcomere branches uniting the myofibrillar network occur more than twice as frequently during early postnatal development as in mature cardiomyocytes. Moreover, we show that the mitochondrial networks arranged in parallel to the contractile apparatus are composed of larger, more compact mitochondria with greater connectivity to adjacent mitochondria in mature as compared with early postnatal cardiomyocytes. Finally, we find that connectivity among mitochondria, LDs and the sarcotubular network is greater in developing than in mature muscles. These data suggest that physical connectivity among cellular structures may facilitate the communication needed to coordinate developmental processes within the cardiac muscle cell. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.
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Affiliation(s)
- Yuho Kim
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Department of Physical Therapy and Kinesiology, University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - Peter T. Ajayi
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Christopher K. E. Bleck
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Brian Glancy
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Demydenko K, Ekhteraei-Tousi S, Roderick HL. Inositol 1,4,5-trisphosphate receptors in cardiomyocyte physiology and disease. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210319. [PMID: 36189803 PMCID: PMC9527928 DOI: 10.1098/rstb.2021.0319] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The contraction of cardiac muscle underlying the pumping action of the heart is mediated by the process of excitation-contraction coupling (ECC). While triggered by Ca2+ entry across the sarcolemma during the action potential, it is the release of Ca2+ from the sarcoplasmic reticulum (SR) intracellular Ca2+ store via ryanodine receptors (RyRs) that plays the major role in induction of contraction. Ca2+ also acts as a key intracellular messenger regulating transcription underlying hypertrophic growth. Although Ca2+ release via RyRs is by far the greatest contributor to the generation of Ca2+ transients in the cardiomyocyte, Ca2+ is also released from the SR via inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs). This InsP3-induced Ca2+ release modifies Ca2+ transients during ECC, participates in directing Ca2+ to the mitochondria, and stimulates the transcription of genes underlying hypertrophic growth. Central to these specific actions of InsP3Rs is their localization to responsible signalling microdomains, the dyad, the SR-mitochondrial interface and the nucleus. In this review, the various roles of InsP3R in cardiac (patho)physiology and the mechanisms by which InsP3 signalling selectively influences the different cardiomyocyte cell processes in which it is involved will be presented. This article is part of the theme issue ‘The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease’.
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Affiliation(s)
- Kateryna Demydenko
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Samaneh Ekhteraei-Tousi
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - H Llewelyn Roderick
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
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Zavodnik IB, Kovalenia TA, Veiko AG, Lapshina EA, Ilyich TV, Kravchuk RI, Zavodnik LB, Klimovich II. [Structural and functional changes in rat liver mitochondria under calcium ion loading in the absence and presence of flavonoids]. BIOMEDITSINSKAIA KHIMIIA 2022; 68:237-249. [PMID: 36005842 DOI: 10.18097/pbmc20226804237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The aim of the present work was to elucidate the mechanisms of calcium ion-induced impairments of the ultrastructure and functional activity of isolated rat liver mitochondria in the absence and presence of a number of flavonoids in vitro. In the presence of exogenous Ca²⁺ (20-60 μM), mitochondrial heterogeneity in size and electron density markedly increased: most organelles demonstrated a swollen electron-light matrix, bigger size, elongated cristae and a reduced their number, a damaged native structure of the inner membrane up to its detachment, and some mitochondria showed a more electron-dense matrix (condensed mitochondria). The calcium-induced opening of the mitochondrial permeability transition pores (MPTP) resulted in the ultrastructural disturbances and in the effective inhibition of the respiratory activity of rat liver mitochondria. The flavonoids (10-25 μM) naringenin and catechin, dose-dependently inhibited the respiratory activity of mitochondria and stimulated the MPTP opening in the presence of Ca²⁺ ions. Since Ruthenium red, an inhibitor of the mitochondrial Ca²⁺ uniporter, effectively prevented Ca²⁺-induced MPTP opening both in the absence and presence of flavonoids, we hypothesized that the effect of flavonoids on the MPTP opening could be mediated by stimulation of the Ca²⁺ uniporter.
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Affiliation(s)
- I B Zavodnik
- Department of Biochemistry, Yanka Kupala State University of Grodno, Grodno, Belarus
| | - T A Kovalenia
- Department of Biochemistry, Yanka Kupala State University of Grodno, Grodno, Belarus
| | - A G Veiko
- Department of Biochemistry, Yanka Kupala State University of Grodno, Grodno, Belarus
| | - E A Lapshina
- Department of Biochemistry, Yanka Kupala State University of Grodno, Grodno, Belarus
| | - T V Ilyich
- Department of Biochemistry, Yanka Kupala State University of Grodno, Grodno, Belarus
| | - R I Kravchuk
- Grodno State Medical University, Grodno, Belarus
| | - L B Zavodnik
- Department of Biochemistry, Yanka Kupala State University of Grodno, Grodno, Belarus
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Assali EA, Sekler I. Sprinkling salt on mitochondria: The metabolic and pathophysiological roles of mitochondrial Na + signaling mediated by NCLX. Cell Calcium 2021; 97:102416. [PMID: 34062329 DOI: 10.1016/j.ceca.2021.102416] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/25/2021] [Accepted: 04/26/2021] [Indexed: 11/25/2022]
Abstract
NCLX, the mitochondrial Na+/Ca2+ transporter is a key player in Ca2+ signaling. However, its role in Na+ signaling is poorly understood. In this review we focus on Na+ signaling by NCLX, and discuss recent physiological and pathophysiological roles attributed to the Na+ influx into mitochondria.
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Affiliation(s)
- Essam A Assali
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84105, Israel
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84105, Israel.
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Torabi N, Noursadeghi E, Shayanfar F, Nazari M, Fahanik-Babaei J, Saghiri R, Khodagholi F, Eliassi A. Intranasal insulin improves the structure-function of the brain mitochondrial ATP-sensitive Ca 2+ activated potassium channel and respiratory chain activities under diabetic conditions. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166075. [PMID: 33444710 DOI: 10.1016/j.bbadis.2021.166075] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 12/06/2020] [Accepted: 12/30/2020] [Indexed: 11/21/2022]
Abstract
Although it is well established that diabetes impairs mitochondrial respiratory chain activity, little is known of the effects of intranasal insulin (INI) on the mitochondrial respiratory chain and structure-function of mitoBKCa channel in diabetes. We have investigated this mechanism in an STZ-induced early type 2 diabetic model. Single ATP-sensitive mitoBKCa channel activity was considered in diabetic and INI-treated rats using a channel incorporated into the bilayer lipid membrane. Because mitoBKCa channels have been involved in mitochondrial respiratory chain activity, a study was undertaken to investigate whether the NADH, complexes I and IV, mitochondrial ROS production, and ΔΨm are altered in an early diabetic model. In this work, we provide evidence for a significant decrease in channel open probability and conductance in diabetic rats. Evidence has been shown that BKCa channel β2 subunits induce a left shift in the BKCa channel voltage dependent curve in low Ca2+ conditions,; our results indicated a significant decrease in mitoBKCa β2 subunits using Western blot analysis. Importantly, INI treatment improved mitoBKCa channel behaviors and β2 subunits expression up to ~70%. We found that early diabetes decreased activities of complex I and IV and increased NADH, ROS production, and ΔΨm. Surprisingly, INI modified the mitochondrial respiratory chain, ROS production, and ΔΨm up to ~70%. Our results thus demonstrate an INI improvement in respiratory chain activity and ROS production in brain mitochondrial preparations coming from the STZ early diabetic rat model, an effect potentially linked to INI improvement in mitoBKCa channel activity and channel β2 subunit expression.
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Affiliation(s)
- Nihad Torabi
- Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Physiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Elham Noursadeghi
- Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Farzad Shayanfar
- Department of Physiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Maryam Nazari
- Department of Physiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Javad Fahanik-Babaei
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Reza Saghiri
- Department of Biochemistry, Pasteur Institute of Iran, Tehran, Iran
| | - Fariba Khodagholi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Evin, Tehran, Iran
| | - Afsaneh Eliassi
- Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Physiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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13
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Docampo R, Vercesi AE, Huang G, Lander N, Chiurillo MA, Bertolini M. Mitochondrial Ca 2+ homeostasis in trypanosomes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 362:261-289. [PMID: 34253297 PMCID: PMC10424509 DOI: 10.1016/bs.ircmb.2021.01.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Mitochondrial calcium ion (Ca2+) uptake is important for buffering cytosolic Ca2+ levels, for regulating cell bioenergetics, and for cell death and autophagy. Ca2+ uptake is mediated by a mitochondrial Ca2+ uniporter (MCU) and the discovery of this channel in trypanosomes has been critical for the identification of the molecular nature of the channel in all eukaryotes. However, the trypanosome uniporter, which has been studied in detail in Trypanosoma cruzi, the agent of Chagas disease, and T. brucei, the agent of human and animal African trypanosomiasis, has lineage-specific adaptations which include the lack of some homologues to mammalian subunits, and the presence of unique subunits. Here, we review newly emerging insights into the role of mitochondrial Ca2+ homeostasis in trypanosomes, the composition of the uniporter, its functional characterization, and its role in general physiology.
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Affiliation(s)
- Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, United States.
| | - Anibal E Vercesi
- Departamento de Patologia Clinica, Universidade Estadual de Campinas, São Paulo, Brazil
| | - Guozhong Huang
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, United States
| | - Noelia Lander
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, United States
| | - Miguel A Chiurillo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, United States
| | - Mayara Bertolini
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, United States
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14
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Amanakis G, Sun J, Fergusson MM, McGinty S, Liu C, Molkentin JD, Murphy E. Cysteine 202 of cyclophilin D is a site of multiple post-translational modifications and plays a role in cardioprotection. Cardiovasc Res 2021; 117:212-223. [PMID: 32129829 PMCID: PMC7797215 DOI: 10.1093/cvr/cvaa053] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 02/11/2020] [Accepted: 02/28/2020] [Indexed: 12/16/2022] Open
Abstract
AIMS Cyclophilin-D is a well-known regulator of the mitochondrial permeability transition pore (PTP), the main effector of cardiac ischaemia/reperfusion injury. However, the binding of CypD to the PTP is poorly understood. Cysteine 202 (C202) of CypD is highly conserved among species and can undergo redox-sensitive post-translational modifications. We investigated whether C202 regulates the opening of PTP. METHODS AND RESULTS We developed a knock-in mouse model using CRISPR where CypD-C202 was mutated to a serine (C202S). Infarct size is reduced in CypD-C202S Langendorff perfused hearts compared to wild type (WT). Cardiac mitochondria from CypD-C202S mice also have higher calcium retention capacity compared to WT. Therefore, we hypothesized that oxidation of C202 might target CypD to the PTP. Indeed, isolated cardiac mitochondria subjected to oxidative stress exhibit less binding of CypD-C202S to the proposed PTP component F1F0-ATP-synthase. We previously found C202 to be S-nitrosylated in ischaemic preconditioning. Cysteine residues can also undergo S-acylation, and C202 matched an S-acylation motif. S-acylation of CypD-C202 was assessed using a resin-assisted capture (Acyl-RAC). WT hearts are abundantly S-acylated on CypD C202 under baseline conditions indicating that S-acylation on C202 per se does not lead to PTP opening. CypD C202S knock-in hearts are protected from ischaemia/reperfusion injury suggesting further that lack of CypD S-acylation at C202 is not detrimental (when C is mutated to S) and does not induce PTP opening. However, we find that ischaemia leads to de-acylation of C202 and that calcium overload in isolated mitochondria promotes de-acylation of CypD. Furthermore, a high bolus of calcium in WT cardiac mitochondria displaces CypD from its physiological binding partners and possibly renders it available for interaction with the PTP. CONCLUSIONS Taken together the data suggest that with ischaemia CypD is de-acylated at C202 allowing the free cysteine residue to undergo oxidation during the first minutes of reperfusion which in turn targets it to the PTP.
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Affiliation(s)
- Georgios Amanakis
- Cardiovascular Branch, NHLBI, National Institutes of Health, Bethesda, MD, USA
| | - Junhui Sun
- Cardiovascular Branch, NHLBI, National Institutes of Health, Bethesda, MD, USA
| | - Maria M Fergusson
- Cardiovascular Branch, NHLBI, National Institutes of Health, Bethesda, MD, USA
| | - Shane McGinty
- Cardiovascular Branch, NHLBI, National Institutes of Health, Bethesda, MD, USA
| | - Chengyu Liu
- Transgenic Core Facility, NHLBI, National Institutes of Health, Bethesda, MD, USA
| | - Jeffery D Molkentin
- Division of Molecular and Cardiovascular Biology, Heart Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Elizabeth Murphy
- Cardiovascular Branch, NHLBI, National Institutes of Health, Bethesda, MD, USA
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15
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Bertolini MS, Docampo R. Different Sensitivity of Control and MICU1- and MICU2-Ablated Trypanosoma cruzi Mitochondrial Calcium Uniporter Complex to Ruthenium-Based Inhibitors. Int J Mol Sci 2020; 21:ijms21239316. [PMID: 33297372 PMCID: PMC7730205 DOI: 10.3390/ijms21239316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 12/03/2020] [Accepted: 12/05/2020] [Indexed: 11/20/2022] Open
Abstract
The mitochondrial Ca2+ uptake in trypanosomatids shares biochemical characteristics with that of animals. However, the composition of the mitochondrial Ca2+ uniporter complex (MCUC) in these parasites is quite peculiar, suggesting lineage-specific adaptations. In this work, we compared the inhibitory activity of ruthenium red (RuRed) and Ru360, the most commonly used MCUC inhibitors, with that of the recently described inhibitor Ru265, on Trypanosoma cruzi, the agent of Chagas disease. Ru265 was more potent than Ru360 and RuRed in inhibiting mitochondrial Ca2+ transport in permeabilized cells. When dose-response effects were investigated, an increase in sensitivity for Ru360 and Ru265 was observed in TcMICU1-KO and TcMICU2-KO cells as compared with control cells. In the presence of RuRed, a significant increase in sensitivity was observed only in TcMICU2-KO cells. However, application of Ru265 to intact cells did not affect growth and respiration of epimastigotes, mitochondrial Ca2+ uptake in Rhod-2-labeled intact cells, or attachment to host cells and infection by trypomastigotes, suggesting a low permeability for this compound in trypanosomes.
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16
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mPTP opening differently affects electron transport chain and oxidative phosphorylation at succinate and NAD-dependent substrates oxidation in permeabilized rat hepatocytes. UKRAINIAN BIOCHEMICAL JOURNAL 2020. [DOI: 10.15407/ubj92.04.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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17
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Assali EA, Jones AE, Veliova M, Acín-Pérez R, Taha M, Miller N, Shum M, Oliveira MF, Las G, Liesa M, Sekler I, Shirihai OS. NCLX prevents cell death during adrenergic activation of the brown adipose tissue. Nat Commun 2020; 11:3347. [PMID: 32620768 PMCID: PMC7334226 DOI: 10.1038/s41467-020-16572-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 05/06/2020] [Indexed: 01/30/2023] Open
Abstract
A sharp increase in mitochondrial Ca2+ marks the activation of brown adipose tissue (BAT) thermogenesis, yet the mechanisms preventing Ca2+ deleterious effects are poorly understood. Here, we show that adrenergic stimulation of BAT activates a PKA-dependent mitochondrial Ca2+ extrusion via the mitochondrial Na+/Ca2+ exchanger, NCLX. Adrenergic stimulation of NCLX-null brown adipocytes (BA) induces a profound mitochondrial Ca2+ overload and impaired uncoupled respiration. Core body temperature, PET imaging of glucose uptake and VO2 measurements confirm a thermogenic defect in NCLX-null mice. We show that Ca2+ overload induced by adrenergic stimulation of NCLX-null BAT, triggers the mitochondrial permeability transition pore (mPTP) opening, leading to a remarkable mitochondrial swelling and cell death. Treatment with mPTP inhibitors rescue mitochondrial function and thermogenesis in NCLX-null BAT, while calcium overload persists. Our findings identify a key pathway through which BA evade apoptosis during adrenergic stimulation of uncoupling. NCLX deletion transforms the adrenergic pathway responsible for thermogenesis activation into a death pathway.
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Affiliation(s)
- Essam A Assali
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84103, Israel
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84105, Israel
| | - Anthony E Jones
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Michaela Veliova
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Rebeca Acín-Pérez
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Mahmoud Taha
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84105, Israel
| | - Nathanael Miller
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Michaël Shum
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Marcus F Oliveira
- Institute of Medical Biochemistry Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Guy Las
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84103, Israel
| | - Marc Liesa
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84105, Israel.
| | - Orian S Shirihai
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA.
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84103, Israel.
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA.
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18
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Huang G, Docampo R. The Mitochondrial Calcium Uniporter Interacts with Subunit c of the ATP Synthase of Trypanosomes and Humans. mBio 2020; 11:e00268-20. [PMID: 32184243 PMCID: PMC7078472 DOI: 10.1128/mbio.00268-20] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 02/12/2020] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial Ca2+ transport mediated by the uniporter complex (MCUC) plays a key role in the regulation of cell bioenergetics in both trypanosomes and mammals. Here we report that Trypanosoma brucei MCU (TbMCU) subunits interact with subunit c of the mitochondrial ATP synthase (ATPc), as determined by coimmunoprecipitation and split-ubiquitin membrane-based yeast two-hybrid (MYTH) assays. Mutagenesis analysis in combination with MYTH assays suggested that transmembrane helices (TMHs) are determinants of this specific interaction. In situ tagging, followed by immunoprecipitation and immunofluorescence microscopy, revealed that T. brucei ATPc (TbATPc) coimmunoprecipitates with TbMCUC subunits and colocalizes with them to the mitochondria. Blue native PAGE and immunodetection analyses indicated that the TbMCUC is present together with the ATP synthase in a large protein complex with a molecular weight of approximately 900 kDa. Ablation of the TbMCUC subunits by RNA interference (RNAi) significantly increased the AMP/ATP ratio, revealing the downregulation of ATP production in the cells. Interestingly, the direct physical MCU-ATPc interaction is conserved in Trypanosoma cruzi and human cells. Specific interaction between human MCU (HsMCU) and human ATPc (HsATPc) was confirmed in vitro by mutagenesis and MYTH assays and in vivo by coimmunoprecipitation. In summary, our study has identified that MCU complex physically interacts with mitochondrial ATP synthase, possibly forming an MCUC-ATP megacomplex that couples ADP and Pi transport with ATP synthesis, a process that is stimulated by Ca2+ in trypanosomes and human cells.IMPORTANCE The mitochondrial calcium uniporter (MCU) is essential for the regulation of oxidative phosphorylation in mammalian cells, and we have shown that in Trypanosoma brucei, the etiologic agent of sleeping sickness, this channel is essential for its survival and infectivity. Here we reveal that that Trypanosoma brucei MCU subunits interact with subunit c of the mitochondrial ATP synthase (ATPc). Interestingly, the direct physical MCU-ATPc interaction is conserved in T. cruzi and human cells.
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Affiliation(s)
- Guozhong Huang
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
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19
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Fisher-Wellman KH, Davidson MT, Narowski TM, Lin CT, Koves TR, Muoio DM. Mitochondrial Diagnostics: A Multiplexed Assay Platform for Comprehensive Assessment of Mitochondrial Energy Fluxes. Cell Rep 2019; 24:3593-3606.e10. [PMID: 30257218 DOI: 10.1016/j.celrep.2018.08.091] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 06/23/2018] [Accepted: 08/29/2018] [Indexed: 12/17/2022] Open
Abstract
Chronic metabolic diseases have been linked to molecular signatures of mitochondrial dysfunction. Nonetheless, molecular remodeling of the transcriptome, proteome, and/or metabolome does not necessarily translate to functional consequences that confer physiologic phenotypes. The work here aims to bridge the gap between molecular and functional phenomics by developing and validating a multiplexed assay platform for comprehensive assessment of mitochondrial energy transduction. The diagnostic power of the platform stems from a modified version of the creatine kinase energetic clamp technique, performed in parallel with multiplexed analyses of dehydrogenase activities and ATP synthesis rates. Together, these assays provide diagnostic coverage of the mitochondrial network at a level approaching that gained by molecular "-omics" technologies. Application of the platform to a comparison of skeletal muscle versus heart mitochondria reveals mechanistic insights into tissue-specific distinctions in energy transfer efficiency. This platform opens exciting opportunities to unravel the connection between mitochondrial bioenergetics and human disease.
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Affiliation(s)
- Kelsey H Fisher-Wellman
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
| | - Michael T Davidson
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
| | - Tara M Narowski
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Timothy R Koves
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
| | - Deborah M Muoio
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA.
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20
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Lu X, Thai PN, Lu S, Pu J, Bers DM. Intrafibrillar and perinuclear mitochondrial heterogeneity in adult cardiac myocytes. J Mol Cell Cardiol 2019; 136:72-84. [PMID: 31491377 DOI: 10.1016/j.yjmcc.2019.08.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 08/12/2019] [Accepted: 08/28/2019] [Indexed: 12/20/2022]
Abstract
Mitochondria are involved in multiple cellular functions, in addition to their core role in energy metabolism. Mitochondria localized in different cellular locations may have different morphology, Ca2+ handling and biochemical properties and may interact differently with other intracellular structures, causing functional specificity. However, most prior studies have utilized isolated mitochondria, removed from their intracellular environment. Mitochondria in cardiac ventricular myocytes are highly organized, with a majority squeezed between the myofilaments in longitudinal chains (intrafibrillar mitochondria, IFM). There is another population of perinuclear mitochondria (PNM) around and between the two nuclei typical in myocytes. Here, we take advantage of live myocyte imaging to test for quantitative morphological and functional differences between IFM and PNM with respect to calcium fluxes, membrane potential, sensitivity to oxidative stress, shape and dynamics. Our findings show higher mitochondrial Ca2+ uptake and oxidative stress sensitivity for IFM vs. PNM, which may relate to higher local energy demand supporting the contractile machinery. In contrast to IFM which are remarkably static, PNM are relatively mobile, appear to participate readily in fission/fusion dynamics and appear to play a central role in mitochondrial genesis and turnover. We conclude that while IFM may be physiologically tuned to support local myofilament energy demands, PNM may be more critical in mitochondrial turnover and regulation of nuclear function and import/export. Thus, important functional differences are present in intrafibrillar vs. perinuclear mitochondrial subpopulations.
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Affiliation(s)
- Xiyuan Lu
- Division of Cardiology, State Key Laboratory for Oncogenes and Related Genes, Renji Hospital School of Medicine, Shanghai Cancer Institute, Jiaotong University, Shanghai, China; Department of Pharmacology, University of California Davis, Davis, CA, USA.
| | - Phung N Thai
- Department of Internal Medicine, University of California Davis, Davis, CA, USA
| | - Shan Lu
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Jun Pu
- Division of Cardiology, State Key Laboratory for Oncogenes and Related Genes, Renji Hospital School of Medicine, Shanghai Cancer Institute, Jiaotong University, Shanghai, China
| | - Donald M Bers
- Department of Pharmacology, University of California Davis, Davis, CA, USA.
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21
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Role of coenzymes in cancer metabolism. Semin Cell Dev Biol 2019; 98:44-53. [PMID: 31176736 DOI: 10.1016/j.semcdb.2019.05.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 05/27/2019] [Accepted: 05/28/2019] [Indexed: 01/18/2023]
Abstract
Cancer is a heterogeneous set of diseases characterized by the rewiring of cellular signaling and the reprogramming of metabolic pathways to sustain growth and proliferation. In past decades, studies were focused primarily on the genetic complexity of cancer. Recently, increasing number of studies have discovered several mutations among metabolic enzymes in different tumor cells. Most of the enzymes are regulated by coenzymes, organic cofactors, that function as intermediate carrier of electrons or functional groups that are transferred during the reaction. However, the precise role of cofactors is not well elucidated. In this review, we discuss several metabolic enzymes associated to cancer metabolism rewiring, whose inhibition may represent a therapeutic target. Such enzymes, upon expression or inhibition, may impact also the coenzymes levels, but only in few cases, it was possible to direct correlate coenzymes changes with a specific enzyme. In addition, we also summarize an up-to-date information on biological role of some coenzymes, preclinical and clinical studies, that have been carried out in various cancers and their outputs.
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22
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Cao JL, Adaniya SM, Cypress MW, Suzuki Y, Kusakari Y, Jhun BS, O-Uchi J. Role of mitochondrial Ca 2+ homeostasis in cardiac muscles. Arch Biochem Biophys 2019; 663:276-287. [PMID: 30684463 PMCID: PMC6469710 DOI: 10.1016/j.abb.2019.01.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/10/2019] [Accepted: 01/22/2019] [Indexed: 12/22/2022]
Abstract
Recent discoveries of the molecular identity of mitochondrial Ca2+ influx/efflux mechanisms have placed mitochondrial Ca2+ transport at center stage in views of cellular regulation in various cell-types/tissues. Indeed, mitochondria in cardiac muscles also possess the molecular components for efficient uptake and extraction of Ca2+. Over the last several years, multiple groups have taken advantage of newly available molecular information about these proteins and applied genetic tools to delineate the precise mechanisms for mitochondrial Ca2+ handling in cardiomyocytes and its contribution to excitation-contraction/metabolism coupling in the heart. Though mitochondrial Ca2+ has been proposed as one of the most crucial secondary messengers in controlling a cardiomyocyte's life and death, the detailed mechanisms of how mitochondrial Ca2+ regulates physiological mitochondrial and cellular functions in cardiac muscles, and how disorders of this mechanism lead to cardiac diseases remain unclear. In this review, we summarize the current controversies and discrepancies regarding cardiac mitochondrial Ca2+ signaling that remain in the field to provide a platform for future discussions and experiments to help close this gap.
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Affiliation(s)
- Jessica L Cao
- Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, USA; Department of Medicine, Division of Cardiology, The Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Stephanie M Adaniya
- Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, USA; Department of Medicine, Division of Cardiology, The Warren Alpert Medical School of Brown University, Providence, RI, USA; Lillehei Heart Institute, Department of Medicine, Cardiovascular Division, University of Minnesota, Minneapolis, MN, USA
| | - Michael W Cypress
- Lillehei Heart Institute, Department of Medicine, Cardiovascular Division, University of Minnesota, Minneapolis, MN, USA
| | - Yuta Suzuki
- Lillehei Heart Institute, Department of Medicine, Cardiovascular Division, University of Minnesota, Minneapolis, MN, USA
| | - Yoichiro Kusakari
- Department of Cell Physiology, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Bong Sook Jhun
- Lillehei Heart Institute, Department of Medicine, Cardiovascular Division, University of Minnesota, Minneapolis, MN, USA
| | - Jin O-Uchi
- Lillehei Heart Institute, Department of Medicine, Cardiovascular Division, University of Minnesota, Minneapolis, MN, USA.
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23
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Doliba NM, Babsky AM, Osbakken MD. The Role of Sodium in Diabetic Cardiomyopathy. Front Physiol 2018; 9:1473. [PMID: 30405433 PMCID: PMC6207851 DOI: 10.3389/fphys.2018.01473] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 09/28/2018] [Indexed: 12/11/2022] Open
Abstract
Cardiovascular complications are the major cause of mortality and morbidity in diabetic patients. The changes in myocardial structure and function associated with diabetes are collectively called diabetic cardiomyopathy. Numerous molecular mechanisms have been proposed that could contribute to the development of diabetic cardiomyopathy and have been studied in various animal models of type 1 or type 2 diabetes. The current review focuses on the role of sodium (Na+) in diabetic cardiomyopathy and provides unique data on the linkage between Na+ flux and energy metabolism, studied with non-invasive 23Na, and 31P-NMR spectroscopy, polarography, and mass spectroscopy. 23Na NMR studies allow determination of the intracellular and extracellular Na+ pools by splitting the total Na+ peak into two resonances after the addition of a shift reagent to the perfusate. Using this technology, we found that intracellular Na+ is approximately two times higher in diabetic cardiomyocytes than in control possibly due to combined changes in the activity of Na+–K+ pump, Na+/H+ exchanger 1 (NHE1) and Na+-glucose cotransporter. We hypothesized that the increase in Na+ activates the mitochondrial membrane Na+/Ca2+ exchanger, which leads to a loss of intramitochondrial Ca2+, with a subsequent alteration in mitochondrial bioenergetics and function. Using isolated mitochondria, we showed that the addition of Na+ (1–10 mM) led to a dose-dependent decrease in oxidative phosphorylation and that this effect was reversed by providing extramitochondrial Ca2+ or by inhibiting the mitochondrial Na+/Ca2+ exchanger with diltiazem. Similar experiments with 31P-NMR in isolated superfused mitochondria embedded in agarose beads showed that Na+ (3–30 mM) led to significantly decreased ATP levels and that this effect was stronger in diabetic rats. These data suggest that in diabetic cardiomyocytes, increased Na+ leads to abnormalities in oxidative phosphorylation and a subsequent decrease in ATP levels. In support of these data, using 31P-NMR, we showed that the baseline β-ATP and phosphocreatine (PCr) were lower in diabetic cardiomyocytes than in control, suggesting that diabetic cardiomyocytes have depressed bioenergetic function. Thus, both altered intracellular Na+ levels and bioenergetics and their interactions may significantly contribute to the pathology of diabetic cardiomyopathy.
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Affiliation(s)
- Nicolai M Doliba
- Department of Biochemistry and Biophysics, Institute for Diabetes, Obesity and Metabolism, School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Andriy M Babsky
- Department of Biophysics and Bioinformatics, Ivan Franko National University of Lviv, Lviv, Ukraine
| | - Mary D Osbakken
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, United States
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Spermatic mitochondria: role in oxidative homeostasis, sperm function and possible tools for their assessment. ZYGOTE 2018; 26:251-260. [PMID: 30223916 DOI: 10.1017/s0967199418000242] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
SummaryDespite sperm mitochondrial relevance to the fertilization capacity, the processes involved in the production of ATP and functional dynamics of sperm mitochondria are not fully understood. One of these processes is the paradox involved between function and formation of reactive oxygen species performed by the organelle. Therefore, this review aimed to provide data on the role of sperm mitochondria in oxidative homeostasis and functionality as well the tools to assess sperm mitochondrial function.
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25
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Jackson JG, Robinson MB. Regulation of mitochondrial dynamics in astrocytes: Mechanisms, consequences, and unknowns. Glia 2017; 66:1213-1234. [PMID: 29098734 DOI: 10.1002/glia.23252] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 09/20/2017] [Accepted: 10/09/2017] [Indexed: 12/15/2022]
Abstract
Astrocytes are the major glial cell in the central nervous system. These polarized cells possess numerous processes that ensheath the vasculature and contact synapses. Astrocytes play important roles in synaptic signaling, neurotransmitter synthesis and recycling, control of nutrient uptake, and control of local blood flow. Many of these processes depend on local metabolism and/or energy utilization. While astrocytes respond to increases in neuronal activity and metabolic demand by upregulating glycolysis and glycogenolysis, astrocytes also possess significant capacity for oxidative (mitochondrial) metabolism. Mitochondria mediate energy supply and metabolism, cellular survival, ionic homeostasis, and proliferation. These organelles are dynamic structures undergoing extensive fission and fusion, directed movement along cytoskeletal tracts, and degradation. While many of the mechanisms underlying the dynamics of these organelles and their physiologic roles have been characterized in neurons and other cells, the roles that mitochondrial dynamics play in glial physiology is less well understood. Recent work from several laboratories has demonstrated that mitochondria are present within the fine processes of astrocytes, that their movement is regulated, and that they contribute to local Ca2+ signaling within the astrocyte. They likely play a role in local ATP production and metabolism, particularly that of glutamate. Here we will review these and other findings describing the mechanism by which mitochondrial dynamics are regulated in astrocytes, how mitochondrial dynamics might influence astrocyte and brain metabolism, and draw parallels to mitochondrial dynamics in neurons. Additionally, we present new analyses of the size, distribution, and dynamics of mitochondria in astrocytes performed using in vivo using 2-photon microscopy.
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Affiliation(s)
- Joshua G Jackson
- Children's Hospital of Philadelphia Research Institute, University of Pennsylvania, Philadelphia, PA, 19104.,Departments of Pediatrics, University of Pennsylvania, Philadelphia, PA, 19104
| | - Michael B Robinson
- Children's Hospital of Philadelphia Research Institute, University of Pennsylvania, Philadelphia, PA, 19104.,Departments of Pediatrics, University of Pennsylvania, Philadelphia, PA, 19104.,Department of Pharmacology, University of Pennsylvania, Philadelphia, PA, 19104
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26
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Li S, Wang Y, Zhao H, He Y, Li J, Jiang G, Xing M. NF-κB-mediated inflammation correlates with calcium overload under arsenic trioxide-induced myocardial damage in Gallus gallus. CHEMOSPHERE 2017; 185:618-627. [PMID: 28728119 DOI: 10.1016/j.chemosphere.2017.07.055] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/10/2017] [Accepted: 07/11/2017] [Indexed: 06/07/2023]
Abstract
Arsenic is a known environmental pollutant and highly hazardous toxin to human health. Due to the biological accumulation, arsenic produces a variety of cardiovascular diseases. However, the exact mechanism is still unclear. Here, our objective was to evaluate myocardial damage and determine the potential mechanism under arsenic exposure in chickens. Arsenic trioxide (As2O3) (1.25 mg/kg BW, corresponding 15 mg/kg feed) was administered as basal diet to male Hy-line chickens (one-day-old) for 4, 8 and 12 weeks. The results showed that As2O3-induced histological and ultrastructural damage in heart accompanied with significantly Ca2+ overload and increased the activities of myocardial enzymes. Moreover, As2O3 exposure significantly increased (P < 0.05) the mRNA levels of ITPR3, PMCA, TRPC1, TRPC3, STIM1, ORAI1 and pro-inflammatory genes, while the mRNA levels of ITPR1, ITPR2, RyR1, RyR3, SERCA, SLC8A1, CACNA1S and interleukin-10 were decreased (P < 0.05) by As2O3 exposure at 4, 8 and 12 weeks as compared with the corresponding control group. Western blot results showed that As2O3 exposure decreased the expression of SERCA and SLC8A1 protein, while the expression of TNF-α, NF-κB, iNOS and PMCA1 increased compared with the corresponding control group. Additionally, correlation analysis and protein-protein interaction prediction shown that NF-κB-mediated inflammatory response have a function correlation with calcium (Ca) regulation-related genes. In conclusion, this study indicated that As2O3-induced inflammatory response might dependent on Ca overload in myocardial damage of chickens. Our work has implications for the development of potential therapeutic approaches by resisting Ca overload for arsenic-induced myocardial damage.
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Affiliation(s)
- Siwen Li
- Department of Physiology, College of Wildlife Resources, Northeast Forestry University, Harbin, 150040, Heilongjiang, PR China.
| | - Yu Wang
- Department of Physiology, College of Wildlife Resources, Northeast Forestry University, Harbin, 150040, Heilongjiang, PR China
| | - Hongjing Zhao
- Department of Physiology, College of Wildlife Resources, Northeast Forestry University, Harbin, 150040, Heilongjiang, PR China
| | - Ying He
- Department of Physiology, College of Wildlife Resources, Northeast Forestry University, Harbin, 150040, Heilongjiang, PR China
| | - Jinglun Li
- Department of Physiology, College of Wildlife Resources, Northeast Forestry University, Harbin, 150040, Heilongjiang, PR China
| | - Guangshun Jiang
- Department of Physiology, College of Wildlife Resources, Northeast Forestry University, Harbin, 150040, Heilongjiang, PR China.
| | - Mingwei Xing
- Department of Physiology, College of Wildlife Resources, Northeast Forestry University, Harbin, 150040, Heilongjiang, PR China.
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27
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Lee JM, Noguchi S. Calcium Dyshomeostasis in Tubular Aggregate Myopathy. Int J Mol Sci 2016; 17:ijms17111952. [PMID: 27879676 PMCID: PMC5133946 DOI: 10.3390/ijms17111952] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 11/15/2016] [Accepted: 11/15/2016] [Indexed: 11/16/2022] Open
Abstract
Calcium is a crucial mediator of cell signaling in skeletal muscles for basic cellular functions and specific functions, including contraction, fiber-type differentiation and energy production. The sarcoplasmic reticulum (SR) is an organelle that provides a large supply of intracellular Ca2+ in myofibers. Upon excitation, it releases Ca2+ into the cytosol, inducing contraction of myofibrils. During relaxation, it takes up cytosolic Ca2+ to terminate the contraction. During exercise, Ca2+ is cycled between the cytosol and the SR through a system by which the Ca2+ pool in the SR is restored by uptake of extracellular Ca2+ via a specific channel on the plasma membrane. This channel is called the store-operated Ca2+ channel or the Ca2+ release-activated Ca2+ channel. It is activated by depletion of the Ca2+ store in the SR by coordination of two main molecules: stromal interaction molecule 1 (STIM1) and calcium release-activated calcium channel protein 1 (ORAI1). Recently, myopathies with a dominant mutation in these genes have been reported and the pathogenic mechanism of such diseases have been proposed. This review overviews the calcium signaling in skeletal muscles and role of store-operated Ca2+ entry in calcium homeostasis. Finally, we discuss the phenotypes and the pathomechanism of myopathies caused by mutations in the STIM1 and ORAI1 genes.
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Affiliation(s)
- Jong-Mok Lee
- Department of Genome Medicine Development, Medical Genome Center, National Center of Neurology and Neuropsychiatry, Kodaira, Tokyo 187-8551, Japan.
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Neuropsychiatry, Kodaira, Tokyo 187-8502, Japan.
| | - Satoru Noguchi
- Department of Genome Medicine Development, Medical Genome Center, National Center of Neurology and Neuropsychiatry, Kodaira, Tokyo 187-8551, Japan.
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Neuropsychiatry, Kodaira, Tokyo 187-8502, Japan.
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28
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Saito R, Takeuchi A, Himeno Y, Inagaki N, Matsuoka S. A simulation study on the constancy of cardiac energy metabolites during workload transition. J Physiol 2016; 594:6929-6945. [PMID: 27530892 DOI: 10.1113/jp272598] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 08/03/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The cardiac energy metabolites such as ATP, phosphocreatine, ADP and NADH are kept relatively constant during physiological cardiac workload transition. How this is accomplished is not yet clarified, though Ca2+ has been suggested to be one of the possible mechanisms. We constructed a detailed mathematical model of cardiac mitochondria based on experimental data and studied whether known Ca2+ -dependent regulation mechanisms play roles in the metabolite constancy. Model simulations revealed that the Ca2+ -dependent regulation mechanisms have important roles under the in vitro condition of isolated mitochondria where malate and glutamate were mitochondrial substrates, while they have only a minor role and the composition of substrates has marked influence on the metabolite constancy during workload transition under the simulated in vivo condition where many substrates exist. These results help us understand the regulation mechanisms of cardiac energy metabolism during physiological cardiac workload transition. ABSTRACT The cardiac energy metabolites such as ATP, phosphocreatine, ADP and NADH are kept relatively constant over a wide range of cardiac workload, though the mechanisms are not yet clarified. One possible regulator of mitochondrial metabolism is Ca2+ , because it activates several mitochondrial enzymes and transporters. Here we constructed a mathematical model of cardiac mitochondria, including oxidative phosphorylation, substrate metabolism and ion/substrate transporters, based on experimental data, and studied whether the Ca2+ -dependent activation mechanisms play roles in metabolite constancy. Under the in vitro condition of isolated mitochondria, where malate and glutamate were used as mitochondrial substrates, the model well reproduced the Ca2+ and inorganic phosphate (Pi ) dependences of oxygen consumption, NADH level and mitochondrial membrane potential. The Ca2+ -dependent activations of the aspartate/glutamate carrier and the F1 Fo -ATPase, and the Pi -dependent activation of Complex III were key factors in reproducing the experimental data. When the mitochondrial model was implemented in a simple cardiac cell model, simulation of workload transition revealed that cytoplasmic Ca2+ concentration ([Ca2+ ]cyt ) within the physiological range markedly increased NADH level. However, the addition of pyruvate or citrate attenuated the Ca2+ dependence of NADH during the workload transition. Under the simulated in vivo condition where malate, glutamate, pyruvate, citrate and 2-oxoglutarate were used as mitochondrial substrates, the energy metabolites were more stable during the workload transition and NADH level was almost insensitive to [Ca2+ ]cyt . It was revealed that mitochondrial substrates have a significant influence on metabolite constancy during cardiac workload transition, and Ca2+ has only a minor role under physiological conditions.
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Affiliation(s)
- Ryuta Saito
- Biology Research Laboratories, Mitsubishi Tanabe Pharma Corporation, Saitama, 335-8505, Japan.,Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Ayako Takeuchi
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan.,Department of Physiology and Biophysics, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - Yukiko Himeno
- Department of Life Science, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Nobuya Inagaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Satoshi Matsuoka
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan.,Department of Physiology and Biophysics, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
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29
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Power ASC, Pham T, Loiselle DS, Crossman DH, Ward ML, Hickey AJ. Impaired ADP channeling to mitochondria and elevated reactive oxygen species in hypertensive hearts. Am J Physiol Heart Circ Physiol 2016; 310:H1649-57. [DOI: 10.1152/ajpheart.00050.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 04/12/2016] [Indexed: 01/20/2023]
Abstract
Systemic hypertension initially promotes a compensatory cardiac hypertrophy, yet it progresses to heart failure (HF), and energetic deficits appear to be central to this failure. However, the transfer of energy between the mitochondria and the myofibrils is not often considered as part of the energetic equation. We compared hearts from old spontaneously hypertensive rats (SHRs) and normotensive Wistar controls. SHR hearts showed a 35% depression in mitochondrial function, yet produced at least double the amount of reactive oxygen species (ROS) in all respiration states in left ventricular (LV) homogenates. To test the connectivity between mitochondria and myofibrils, respiration was further tested in situ with LV permeabilized fibers by addition of multiple substrates and ATP, which requires hydrolysis to mediate oxidative phosphorylation. By trapping ADP using a pyruvate kinase enzyme system, we tested ADP channeling towards mitochondria, and this suppressed respiration and elevated ROS production more in the SHR fibers. The ADP-trapped state was also less relieved on creatine addition, likely reflecting the 30% depression in total CK activity in the SHR heart fibers. Confocal imaging identified a 34% longer distance between the centers of myofibril to mitochondria in the SHR hearts, which increases transverse metabolite diffusion distances (e.g., for ATP, ADP, and creatine phosphate). We propose that impaired connectivity between mitochondria and myofibrils may contribute to elevated ROS production. Impaired energy exchange could be the result of ultrastructural changes that occur with hypertrophy in this model of hypertension.
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Affiliation(s)
- Amelia S. C. Power
- School of Biological Sciences, Faculty of Science, The University of Auckland, Auckland, New Zealand; and
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Toan Pham
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Denis S. Loiselle
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand; and
| | - David H. Crossman
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Marie-Louise Ward
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Anthony J. Hickey
- School of Biological Sciences, Faculty of Science, The University of Auckland, Auckland, New Zealand; and
- Maurice Wilkins Centre, The University of Auckland, Auckland, New Zealand
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30
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Myocardial Microcirculation and Mitochondrial Energetics in the Isolated Rat Heart. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 876:159-165. [PMID: 26782208 DOI: 10.1007/978-1-4939-3023-4_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Normal functioning of myocardium requires adequate oxygenation, which in turn is dependent on an adequate microcirculation. NADH-fluorimetry enables a direct evaluation of the adequacy of tissue oxygenation while the measurement of quenching of Pd-porphyrine (PpIX) phosphorescence enables quantitative measurement of microvascular pO2. Combination of these two techniques provides information about the relation between microvascular oxygen content and parenchymal oxygen availability in Langendorff hearts. In normal myocardium there is heterogeneity at the microcirculatory level resulting in the existence of microcirculatory weak units, originating at the capillary level, which reoxygenate the slowest upon reoxygenation after an episode of ischemia. Sepsis and myocardial hypertrophia alter the pattern of oxygen transport whereby the microcirculation is disturbed at the arteriolar/arterial level. NADH fluorimetry also reveals a disturbance of mitochondrial oxygen availability in sepsis. Furthermore it is shown that these techniques can also be applied to various organs and tissues in vivo.
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31
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Vinnakota KC, Cha CY, Rorsman P, Balaban RS, La Gerche A, Wade-Martins R, Beard DA, Jeneson JAL. Improving the physiological realism of experimental models. Interface Focus 2016; 6:20150076. [PMID: 27051507 PMCID: PMC4759746 DOI: 10.1098/rsfs.2015.0076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The Virtual Physiological Human (VPH) project aims to develop integrative, explanatory and predictive computational models (C-Models) as numerical investigational tools to study disease, identify and design effective therapies and provide an in silico platform for drug screening. Ultimately, these models rely on the analysis and integration of experimental data. As such, the success of VPH depends on the availability of physiologically realistic experimental models (E-Models) of human organ function that can be parametrized to test the numerical models. Here, the current state of suitable E-models, ranging from in vitro non-human cell organelles to in vivo human organ systems, is discussed. Specifically, challenges and recent progress in improving the physiological realism of E-models that may benefit the VPH project are highlighted and discussed using examples from the field of research on cardiovascular disease, musculoskeletal disorders, diabetes and Parkinson's disease.
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Affiliation(s)
- Kalyan C. Vinnakota
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Chae Y. Cha
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Robert S. Balaban
- Laboratory of Cardiac Energetics, National Heart Lung Blood Institute, Bethesda, MD, USA
| | - Andre La Gerche
- Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - Richard Wade-Martins
- Oxford Parkinson's Disease Centre, University of Oxford, Oxford, UK
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Daniel A. Beard
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Jeroen A. L. Jeneson
- Neuroimaging Centre, Division of Neuroscience, University Medical Center Groningen, Groningen, The Netherlands
- Department of Radiology, Academic Medical Center Amsterdam, University of Amsterdam, Amsterdam, The Netherlands
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32
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Ge L, Villinger S, Mari SA, Giller K, Griesinger C, Becker S, Müller DJ, Zweckstetter M. Molecular Plasticity of the Human Voltage-Dependent Anion Channel Embedded Into a Membrane. Structure 2016; 24:585-594. [PMID: 27021164 PMCID: PMC5654509 DOI: 10.1016/j.str.2016.02.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 02/12/2016] [Accepted: 02/22/2016] [Indexed: 12/28/2022]
Abstract
The voltage-dependent anion channel (VDAC) regulates the flux of metabolites and ions across the outer mitochondrial membrane. Regulation of ion flow involves conformational transitions in VDAC, but the nature of these changes has not been resolved to date. By combining single-molecule force spectroscopy with nuclear magnetic resonance spectroscopy we show that the β barrel of human VDAC embedded into a membrane is highly flexible. Its mechanical flexibility exceeds by up to one order of magnitude that determined for β strands of other membrane proteins and is largest in the N-terminal part of the β barrel. Interaction with Ca(2+), a key regulator of metabolism and apoptosis, considerably decreases the barrel's conformational variability and kinetic free energy in the membrane. The combined data suggest that physiological VDAC function depends on the molecular plasticity of its channel.
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Affiliation(s)
- Lin Ge
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Saskia Villinger
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Stefania A Mari
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Karin Giller
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Christian Griesinger
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Stefan Becker
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Daniel J Müller
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Mattenstrasse 26, 4058 Basel, Switzerland.
| | - Markus Zweckstetter
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany; Structural Biology in Dementia, German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Strasse 3a, 37075 Göttingen, Germany; Department of Neurology, University Medical Center Göttingen, University of Göttingen, Am Waldweg 33, 37073 Göttingen, Germany.
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33
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Walters JW, Amos D, Ray K, Santanam N. Mitochondrial redox status as a target for cardiovascular disease. Curr Opin Pharmacol 2016; 27:50-5. [PMID: 26894468 DOI: 10.1016/j.coph.2016.01.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 01/25/2016] [Accepted: 01/29/2016] [Indexed: 02/07/2023]
Abstract
Mitochondria are major players in cellular energetics, oxidative stress and programmed cell death. Mitochondrial dynamics regulate and integrate these functions. Mitochondrial dysfunction is involved in cardiac hypertrophy, hypertension and myocardial ischemia/reperfusion injury. Reactive oxygen species generation is modulated by the fusion-fission pathway as well as key proteins such as sirtuins that act as metabolic sensors of cellular energetics. Mitochondrial redox status has thus become a good target for therapy against cardiovascular diseases. Recently, there is an influx of studies garnered towards assessing the beneficial effects of mitochondrial targeted antioxidants, drugs modulating the fusion-fission proteins, sirtuins, and other mitochondrial processes as potential cardio-protecting agents.
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Affiliation(s)
- James W Walters
- School of Arts & Sciences, Bluefield State College, Basic Science Building B213, 219 Rock Street, Bluefield, WV 24701, USA
| | - Deborah Amos
- Department of Pharmacology, Physiology & Toxicology, Joan C Edwards School of Medicine, Marshall University, One John Marshall Dr, Huntington, WV 25755, USA
| | - Kristeena Ray
- Department of Pharmacology, Physiology & Toxicology, Joan C Edwards School of Medicine, Marshall University, One John Marshall Dr, Huntington, WV 25755, USA
| | - Nalini Santanam
- Department of Pharmacology, Physiology & Toxicology, Joan C Edwards School of Medicine, Marshall University, One John Marshall Dr, Huntington, WV 25755, USA.
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34
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Winslow RL, Walker MA, Greenstein JL. Modeling calcium regulation of contraction, energetics, signaling, and transcription in the cardiac myocyte. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2015; 8:37-67. [PMID: 26562359 DOI: 10.1002/wsbm.1322] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 09/29/2015] [Accepted: 09/30/2015] [Indexed: 12/11/2022]
Abstract
Calcium (Ca(2+)) plays many important regulatory roles in cardiac muscle cells. In the initial phase of the action potential, influx of Ca(2+) through sarcolemmal voltage-gated L-type Ca(2+) channels (LCCs) acts as a feed-forward signal that triggers a large release of Ca(2+) from the junctional sarcoplasmic reticulum (SR). This Ca(2+) drives heart muscle contraction and pumping of blood in a process known as excitation-contraction coupling (ECC). Triggered and released Ca(2+) also feed back to inactivate LCCs, attenuating the triggered Ca(2+) signal once release has been achieved. The process of ECC consumes large amounts of ATP. It is now clear that in a process known as excitation-energetics coupling, Ca(2+) signals exert beat-to-beat regulation of mitochondrial ATP production that closely couples energy production with demand. This occurs through transport of Ca(2+) into mitochondria, where it regulates enzymes of the tricarboxylic acid cycle. In excitation-signaling coupling, Ca(2+) activates a number of signaling pathways in a feed-forward manner. Through effects on their target proteins, these interconnected pathways regulate Ca(2+) signals in complex ways to control electrical excitability and contractility of heart muscle. In a process known as excitation-transcription coupling, Ca(2+) acting primarily through signal transduction pathways also regulates the process of gene transcription. Because of these diverse and complex roles, experimentally based mechanistic computational models are proving to be very useful for understanding Ca(2+) signaling in the cardiac myocyte.
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Affiliation(s)
- Raimond L Winslow
- Institute for Computational Medicine and Department of Biomedical Engineering, The Johns Hopkins University School of Medicine and Whiting School of Engineering, Baltimore, MD, USA
| | - Mark A Walker
- Institute for Computational Medicine and Department of Biomedical Engineering, The Johns Hopkins University School of Medicine and Whiting School of Engineering, Baltimore, MD, USA
| | - Joseph L Greenstein
- Institute for Computational Medicine and Department of Biomedical Engineering, The Johns Hopkins University School of Medicine and Whiting School of Engineering, Baltimore, MD, USA
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35
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Bernardi P, Rasola A, Forte M, Lippe G. The Mitochondrial Permeability Transition Pore: Channel Formation by F-ATP Synthase, Integration in Signal Transduction, and Role in Pathophysiology. Physiol Rev 2015; 95:1111-55. [PMID: 26269524 DOI: 10.1152/physrev.00001.2015] [Citation(s) in RCA: 420] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The mitochondrial permeability transition (PT) is a permeability increase of the inner mitochondrial membrane mediated by a channel, the permeability transition pore (PTP). After a brief historical introduction, we cover the key regulatory features of the PTP and provide a critical assessment of putative protein components that have been tested by genetic analysis. The discovery that under conditions of oxidative stress the F-ATP synthases of mammals, yeast, and Drosophila can be turned into Ca(2+)-dependent channels, whose electrophysiological properties match those of the corresponding PTPs, opens new perspectives to the field. We discuss structural and functional features of F-ATP synthases that may provide clues to its transition from an energy-conserving into an energy-dissipating device as well as recent advances on signal transduction to the PTP and on its role in cellular pathophysiology.
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Affiliation(s)
- Paolo Bernardi
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Andrea Rasola
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Michael Forte
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Giovanna Lippe
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
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Bernardi P, Di Lisa F, Fogolari F, Lippe G. From ATP to PTP and Back: A Dual Function for the Mitochondrial ATP Synthase. Circ Res 2015; 116:1850-62. [PMID: 25999424 DOI: 10.1161/circresaha.115.306557] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mitochondria not only play a fundamental role in heart physiology but are also key effectors of dysfunction and death. This dual role assumes a new meaning after recent advances on the nature and regulation of the permeability transition pore, an inner membrane channel whose opening requires matrix Ca(2+) and is modulated by many effectors including reactive oxygen species, matrix cyclophilin D, Pi (inorganic phosphate), and matrix pH. The recent demonstration that the F-ATP synthase can reversibly undergo a Ca(2+)-dependent transition to form a channel that mediates the permeability transition opens new perspectives to the field. These findings demand a reassessment of the modifications of F-ATP synthase that take place in the heart under pathological conditions and of their potential role in determining the transition of F-ATP synthase from and energy-conserving into an energy-dissipating device.
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Affiliation(s)
- Paolo Bernardi
- From the Department of Biomedical Sciences, University of Padova, Italy (P.B., F.D.L.); and Department of Medical and Biological Sciences (F.F) and Department of Food Science (G.L.), University of Udine, Udine, Italy.
| | - Fabio Di Lisa
- From the Department of Biomedical Sciences, University of Padova, Italy (P.B., F.D.L.); and Department of Medical and Biological Sciences (F.F) and Department of Food Science (G.L.), University of Udine, Udine, Italy
| | - Federico Fogolari
- From the Department of Biomedical Sciences, University of Padova, Italy (P.B., F.D.L.); and Department of Medical and Biological Sciences (F.F) and Department of Food Science (G.L.), University of Udine, Udine, Italy
| | - Giovanna Lippe
- From the Department of Biomedical Sciences, University of Padova, Italy (P.B., F.D.L.); and Department of Medical and Biological Sciences (F.F) and Department of Food Science (G.L.), University of Udine, Udine, Italy
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Covian R, French S, Kusnetz H, Balaban RS. Stimulation of oxidative phosphorylation by calcium in cardiac mitochondria is not influenced by cAMP and PKA activity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1837:1913-1921. [PMID: 25178840 DOI: 10.1016/j.bbabio.2014.08.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 08/21/2014] [Accepted: 08/23/2014] [Indexed: 12/31/2022]
Abstract
Cardiac oxidative ATP generation is finely tuned to match several-fold increases in energy demand. Calcium has been proposed to play a role in the activation of ATP production via PKA phosphorylation in response to intramitochondrial cAMP generation. We evaluated the effect of cAMP, its membrane permeable analogs (dibutyryl-cAMP, 8-bromo-cAMP), and the PKA inhibitor H89 on respiration of isolated pig heart mitochondria. cAMP analogs did not stimulate State 3 respiration of Ca2 +-depleted mitochondria (82.2 ± 3.6% of control), in contrast to the 2-fold activation induced by 0.95 μM free Ca2 +, which was unaffected by H89. Using fluorescence and integrating sphere spectroscopy, we determined that Ca2 + increased the reduction of NADH (8%), and of cytochromes bH (3%), c1 (3%), c (4%), and a (2%), together with a doubling of conductances for Complex I + III and Complex IV. None of these changes were induced by cAMP analogs nor abolished by H89. In Ca2 +-undepleted mitochondria, we observed only slight changes in State 3 respiration rates upon addition of 50 μM cAMP (85 ± 9.9%), dibutyryl-cAMP (80.1 ± 5.2%), 8-bromo-cAMP (88.6 ± 3.3%), or 1 μM H89 (89.7 ± 19.9%) with respect to controls. Similar results were obtained when measuring respiration in heart homogenates. Addition of exogenous PKA with dibutyryl-cAMP or the constitutively active catalytic subunit of PKA to isolated mitochondria decreased State 3 respiration by only 5–15%. These functional studies suggest that alterations in mitochondrial cAMP and PKA activity do not contribute significantly to the acute Ca2 + stimulation of oxidative phosphorylation
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Affiliation(s)
- Raul Covian
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center Dr, Room B1D416, Bethesda, MD 20892, USA.
| | - Stephanie French
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center Dr, Room B1D416, Bethesda, MD 20892, USA
| | - Heather Kusnetz
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center Dr, Room B1D416, Bethesda, MD 20892, USA
| | - Robert S Balaban
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center Dr, Room B1D416, Bethesda, MD 20892, USA
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Lengert N, Drossel B. In silico analysis of exercise intolerance in myalgic encephalomyelitis/chronic fatigue syndrome. Biophys Chem 2015; 202:21-31. [PMID: 25899994 DOI: 10.1016/j.bpc.2015.03.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 03/26/2015] [Accepted: 03/28/2015] [Indexed: 11/16/2022]
Abstract
Post-exertional malaise is commonly observed in patients with myalgic encephalomyelitis/chronic fatigue syndrome, but its mechanism is not yet well understood. A reduced capacity for mitochondrial ATP synthesis is associated with the pathogenesis of CFS and is suspected to be a major contribution to exercise intolerance in CFS patients. To demonstrate the connection between a reduced mitochondrial capacity and exercise intolerance, we present a model which simulates metabolite dynamics in skeletal muscles during exercise and recovery. CFS simulations exhibit critically low levels of ATP, where an increased rate of cell death would be expected. To stabilize the energy supply at low ATP concentrations the total adenine nucleotide pool is reduced substantially causing a prolonged recovery time even without consideration of other factors, such as immunological dysregulations and oxidative stress. Repeated exercises worsen this situation considerably. Furthermore, CFS simulations exhibited an increased acidosis and lactate accumulation consistent with experimental observations.
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Affiliation(s)
- Nicor Lengert
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany.
| | - Barbara Drossel
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
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Li Q, Su D, O'Rourke B, Pogwizd SM, Zhou L. Mitochondria-derived ROS bursts disturb Ca²⁺ cycling and induce abnormal automaticity in guinea pig cardiomyocytes: a theoretical study. Am J Physiol Heart Circ Physiol 2014; 308:H623-36. [PMID: 25539710 DOI: 10.1152/ajpheart.00493.2014] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mitochondria are in close proximity to the redox-sensitive sarcoplasmic reticulum (SR) Ca(2+) release [ryanodine receptors (RyRs)] and uptake [Ca(2+)-ATPase (SERCA)] channels. Thus mitochondria-derived reactive oxygen species (mdROS) could play a crucial role in modulating Ca(2+) cycling in the cardiomyocytes. However, whether mdROS-mediated Ca(2+) dysregulation translates to abnormal electrical activities under pathological conditions, and if yes what are the underlying ionic mechanisms, have not been fully elucidated. We hypothesize that pathological mdROS induce Ca(2+) elevation by modulating SR Ca(2+) handling, which activates other Ca(2+) channels and further exacerbates Ca(2+) dysregulation, leading to abnormal action potential (AP). We also propose that the morphologies of elicited AP abnormality rely on the time of mdROS induction, interaction between mitochondria and SR, and intensity of mitochondrial oxidative stress. To test the hypotheses, we developed a multiscale guinea pig cardiomyocyte model that incorporates excitation-contraction coupling, local Ca(2+) control, mitochondrial energetics, and ROS-induced ROS release. This model, for the first time, includes mitochondria-SR microdomain and modulations of mdROS on RyR and SERCA activities. Simulations show that mdROS bursts increase cytosolic Ca(2+) by stimulating RyRs and inhibiting SERCA, which activates the Na(+)/Ca(2+) exchanger, Ca(2+)-sensitive nonspecific cationic channels, and Ca(2+)-induced Ca(2+) release, eliciting abnormal AP. The morphologies of AP abnormality are largely influenced by the time interval among mdROS burst induction and AP firing, dosage and diffusion of mdROS, and SR-mitochondria distance. This study defines the role of mdROS in Ca(2+) overload-mediated cardiac arrhythmogenesis and underscores the importance of considering mitochondrial targets in designing new antiarrhythmic therapies.
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Affiliation(s)
- Qince Li
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; Cardiac Rhythm Management Laboratory, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Di Su
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; Cardiac Rhythm Management Laboratory, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Brian O'Rourke
- Division of Cardiology, Department of Medicine, The Johns Hopkins University, Baltimore, Maryland
| | - Steven M Pogwizd
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; Cardiac Rhythm Management Laboratory, University of Alabama at Birmingham, Birmingham, Alabama; and Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Lufang Zhou
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; Cardiac Rhythm Management Laboratory, University of Alabama at Birmingham, Birmingham, Alabama; and Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama; and
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Birkedal R, Laasmaa M, Vendelin M. The location of energetic compartments affects energetic communication in cardiomyocytes. Front Physiol 2014; 5:376. [PMID: 25324784 PMCID: PMC4178378 DOI: 10.3389/fphys.2014.00376] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 09/10/2014] [Indexed: 01/08/2023] Open
Abstract
The heart relies on accurate regulation of mitochondrial energy supply to match energy demand. The main regulators are Ca2+ and feedback of ADP and Pi. Regulation via feedback has intrigued for decades. First, the heart exhibits a remarkable metabolic stability. Second, diffusion of ADP and other molecules is restricted specifically in heart and red muscle, where a fast feedback is needed the most. To explain the regulation by feedback, compartmentalization must be taken into account. Experiments and theoretical approaches suggest that cardiomyocyte energetic compartmentalization is elaborate with barriers obstructing diffusion in the cytosol and at the level of the mitochondrial outer membrane (MOM). A recent study suggests the barriers are organized in a lattice with dimensions in agreement with those of intracellular structures. Here, we discuss the possible location of these barriers. The more plausible scenario includes a barrier at the level of MOM. Much research has focused on how the permeability of MOM itself is regulated, and the importance of the creatine kinase system to facilitate energetic communication. We hypothesize that at least part of the diffusion restriction at the MOM level is not by MOM itself, but due to the close physical association between the sarcoplasmic reticulum (SR) and mitochondria. This will explain why animals with a disabled creatine kinase system exhibit rather mild phenotype modifications. Mitochondria are hubs of energetics, but also ROS production and signaling. The close association between SR and mitochondria may form a diffusion barrier to ADP added outside a permeabilized cardiomyocyte. But in vivo, it is the structural basis for the mitochondrial-SR coupling that is crucial for the regulation of mitochondrial Ca2+-transients to regulate energetics, and for avoiding Ca2+-overload and irreversible opening of the mitochondrial permeability transition pore.
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Affiliation(s)
- Rikke Birkedal
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology Tallinn, Estonia
| | - Martin Laasmaa
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology Tallinn, Estonia
| | - Marko Vendelin
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology Tallinn, Estonia
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O-Uchi J, Ryu SY, Jhun BS, Hurst S, Sheu SS. Mitochondrial ion channels/transporters as sensors and regulators of cellular redox signaling. Antioxid Redox Signal 2014; 21:987-1006. [PMID: 24180309 PMCID: PMC4116125 DOI: 10.1089/ars.2013.5681] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
SIGNIFICANCE Mitochondrial ion channels/transporters and the electron transport chain (ETC) serve as key sensors and regulators for cellular redox signaling, the production of reactive oxygen species (ROS) and nitrogen species (RNS) in mitochondria, and balancing cell survival and death. Although the functional and pharmacological characteristics of mitochondrial ion transport mechanisms have been extensively studied for several decades, the majority of the molecular identities that are responsible for these channels/transporters have remained a mystery until very recently. RECENT ADVANCES Recent breakthrough studies uncovered the molecular identities of the diverse array of major mitochondrial ion channels/transporters, including the mitochondrial Ca2+ uniporter pore, mitochondrial permeability transition pore, and mitochondrial ATP-sensitive K+ channel. This new information enables us to form detailed molecular and functional characterizations of mitochondrial ion channels/transporters and their roles in mitochondrial redox signaling. CRITICAL ISSUES Redox-mediated post-translational modifications of mitochondrial ion channels/transporters and ETC serve as key mechanisms for the spatiotemporal control of mitochondrial ROS/RNS generation. FUTURE DIRECTIONS Identification of detailed molecular mechanisms for redox-mediated regulation of mitochondrial ion channels will enable us to find novel therapeutic targets for many diseases that are associated with cellular redox signaling and mitochondrial ion channels/transporters.
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Affiliation(s)
- Jin O-Uchi
- 1 Department of Medicine, Center for Translational Medicine, Jefferson Medical College, Thomas Jefferson University , Philadelphia, Pennsylvania
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Yang KC, Bonini MG, Dudley SC. Mitochondria and arrhythmias. Free Radic Biol Med 2014; 71:351-361. [PMID: 24713422 PMCID: PMC4096785 DOI: 10.1016/j.freeradbiomed.2014.03.033] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 03/21/2014] [Accepted: 03/24/2014] [Indexed: 12/31/2022]
Abstract
Mitochondria are essential to providing ATP, thereby satisfying the energy demand of the incessant electrical activity and contractile action of cardiac muscle. Emerging evidence indicates that mitochondrial dysfunction can adversely affect cardiac electrical functioning by impairing the intracellular ion homeostasis and membrane excitability through reduced ATP production and excessive reactive oxygen species (ROS) generation, resulting in increased propensity to cardiac arrhythmias. In this review, the molecular mechanisms linking mitochondrial dysfunction to cardiac arrhythmias are discussed with an emphasis on the impact of increased mitochondrial ROS on the cardiac ion channels and transporters that are critical to maintaining normal electromechanical functioning of the cardiomyocytes. The potential of using mitochondria-targeted antioxidants as a novel antiarrhythmia therapy is highlighted.
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Affiliation(s)
- Kai-Chien Yang
- Lifespan Cardiovascular Institute, Providence VA Medical Center, and Brown University, Providence, RI 02903, USA
| | - Marcelo G Bonini
- Department of Medicine/Cardiology, University of Illinois at Chicago, Chicago, IL 60612, USA; Department of Pathology, and University of Illinois at Chicago, Chicago, IL 60612, USA; Department of Pharmacology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Samuel C Dudley
- Lifespan Cardiovascular Institute, Providence VA Medical Center, and Brown University, Providence, RI 02903, USA.
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Clanton TL, Hogan MC, Gladden LB. Regulation of cellular gas exchange, oxygen sensing, and metabolic control. Compr Physiol 2013; 3:1135-90. [PMID: 23897683 DOI: 10.1002/cphy.c120030] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cells must continuously monitor and couple their metabolic requirements for ATP utilization with their ability to take up O2 for mitochondrial respiration. When O2 uptake and delivery move out of homeostasis, cells have elaborate and diverse sensing and response systems to compensate. In this review, we explore the biophysics of O2 and gas diffusion in the cell, how intracellular O2 is regulated, how intracellular O2 levels are sensed and how sensing systems impact mitochondrial respiration and shifts in metabolic pathways. Particular attention is paid to how O2 affects the redox state of the cell, as well as the NO, H2S, and CO concentrations. We also explore how these agents can affect various aspects of gas exchange and activate acute signaling pathways that promote survival. Two kinds of challenges to gas exchange are also discussed in detail: when insufficient O2 is available for respiration (hypoxia) and when metabolic requirements test the limits of gas exchange (exercising skeletal muscle). This review also focuses on responses to acute hypoxia in the context of the original "unifying theory of hypoxia tolerance" as expressed by Hochachka and colleagues. It includes discourse on the regulation of mitochondrial electron transport, metabolic suppression, shifts in metabolic pathways, and recruitment of cell survival pathways preventing collapse of membrane potential and nuclear apoptosis. Regarding exercise, the issues discussed relate to the O2 sensitivity of metabolic rate, O2 kinetics in exercise, and influences of available O2 on glycolysis and lactate production.
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Affiliation(s)
- T L Clanton
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA.
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Martinez-Finley EJ, Gavin CE, Aschner M, Gunter TE. Manganese neurotoxicity and the role of reactive oxygen species. Free Radic Biol Med 2013; 62:65-75. [PMID: 23395780 PMCID: PMC3713115 DOI: 10.1016/j.freeradbiomed.2013.01.032] [Citation(s) in RCA: 210] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 01/25/2013] [Accepted: 01/28/2013] [Indexed: 12/21/2022]
Abstract
Manganese (Mn) is an essential dietary nutrient, but an excess or accumulation can be toxic. Disease states, such as manganism, are associated with overexposure or accumulation of Mn and are due to the production of reactive oxygen species, free radicals, and toxic metabolites; alteration of mitochondrial function and ATP production; and depletion of cellular antioxidant defense mechanisms. This review focuses on all of the preceding mechanisms and the scientific studies that support them as well as providing an overview of the absorption, distribution, and excretion of Mn and the stability and transport of Mn compounds in the body.
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Affiliation(s)
- Ebany J Martinez-Finley
- Division of Clinical Pharmacology and Pediatric Toxicology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37240, USA; Center in Molecular Toxicology, Vanderbilt University Medical Center, Nashville, TN 37240, USA
| | | | - Michael Aschner
- Division of Clinical Pharmacology and Pediatric Toxicology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37240, USA; Center in Molecular Toxicology, Vanderbilt University Medical Center, Nashville, TN 37240, USA; Center for Molecular Neuroscience, Vanderbilt University Medical Center, Nashville, TN 37240, USA; The Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN 37240, USA.
| | - Thomas E Gunter
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
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Eisner V, Csordás G, Hajnóczky G. Interactions between sarco-endoplasmic reticulum and mitochondria in cardiac and skeletal muscle - pivotal roles in Ca²⁺ and reactive oxygen species signaling. J Cell Sci 2013; 126:2965-78. [PMID: 23843617 DOI: 10.1242/jcs.093609] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mitochondria are strategically and dynamically positioned in the cell to spatially coordinate ATP production with energy needs and to allow the local exchange of material with other organelles. Interactions of mitochondria with the sarco-endoplasmic reticulum (SR/ER) have been receiving much attention owing to emerging evidence on the role these sites have in cell signaling, dynamics and biosynthetic pathways. One of the most important physiological and pathophysiological paradigms for SR/ER-mitochondria interactions is in cardiac and skeletal muscle. The contractile activity of these tissues has to be matched by mitochondrial ATP generation that is achieved, at least in part, by propagation of Ca(2+) signals from SR to mitochondria. However, the muscle has a highly ordered structure, providing only limited opportunity for mitochondrial dynamics and interorganellar interactions. This Commentary focuses on the latest advances in the structure, function and disease relevance of the communication between SR/ER and mitochondria in muscle. In particular, we discuss the recent demonstration of SR/ER-mitochondria tethers that are formed by multiple proteins, and local Ca(2+) transfer between SR/ER and mitochondria.
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Affiliation(s)
- Verónica Eisner
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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Glancy B, Willis WT, Chess DJ, Balaban RS. Effect of calcium on the oxidative phosphorylation cascade in skeletal muscle mitochondria. Biochemistry 2013; 52:2793-809. [PMID: 23547908 DOI: 10.1021/bi3015983] [Citation(s) in RCA: 227] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Calcium is believed to regulate mitochondrial oxidative phosphorylation, thereby contributing to the maintenance of cellular energy homeostasis. Skeletal muscle, with an energy conversion dynamic range of up to 100-fold, is an extreme case for evaluating the cellular balance of ATP production and consumption. This study examined the role of Ca(2+) in the entire oxidative phosphorylation reaction network in isolated skeletal muscle mitochondria and attempted to extrapolate these results back to the muscle, in vivo. Kinetic analysis was conducted to evaluate the dose-response effect of Ca(2+) on the maximal velocity of oxidative phosphorylation (V(maxO)) and the ADP affinity. Force-flow analysis evaluated the interplay between energetic driving forces and flux to determine the conductance, or effective activity, of individual steps within oxidative phosphorylation. Measured driving forces [extramitochondrial phosphorylation potential (ΔG(ATP)), membrane potential, and redox states of NADH and cytochromes b(H), b(L), c(1), c, and a,a(3)] were compared with flux (oxygen consumption) at 37 °C; 840 nM Ca(2+) generated an ~2-fold increase in V(maxO) with no change in ADP affinity (~43 μM). Force-flow analysis revealed that Ca(2+) activation of V(maxO) was distributed throughout the oxidative phosphorylation reaction sequence. Specifically, Ca(2+) increased the conductance of Complex IV (2.3-fold), Complexes I and III (2.2-fold), ATP production/transport (2.4-fold), and fuel transport/dehydrogenases (1.7-fold). These data support the notion that Ca(2+) activates the entire muscle oxidative phosphorylation cascade, while extrapolation of these data to the exercising muscle predicts a significant role of Ca(2+) in maintaining cellular energy homeostasis.
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Affiliation(s)
- Brian Glancy
- Laboratory of Cardiac Energetics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Boelens AD, Pradhan RK, Blomeyer CA, Camara AKS, Dash RK, Stowe DF. Extra-matrix Mg2+ limits Ca2+ uptake and modulates Ca2+ uptake-independent respiration and redox state in cardiac isolated mitochondria. J Bioenerg Biomembr 2013; 45:203-18. [PMID: 23456198 DOI: 10.1007/s10863-013-9500-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 01/24/2013] [Indexed: 12/20/2022]
Abstract
Cardiac mitochondrial matrix (m) free Ca(2+) ([Ca(2+)]m) increases primarily by Ca(2+) uptake through the Ca(2+) uniporter (CU). Ca(2+) uptake via the CU is attenuated by extra-matrix (e) Mg(2+) ([Mg(2+)]e). How [Ca(2+)]m is dynamically modulated by interacting physiological levels of [Ca(2+)]e and [Mg(2+)]e and how this interaction alters bioenergetics are not well understood. We postulated that as [Mg(2+)]e modulates Ca(2+) uptake via the CU, it also alters bioenergetics in a matrix Ca(2+)-induced and matrix Ca(2+)-independent manner. To test this, we measured changes in [Ca(2+)]e, [Ca(2+)]m, [Mg(2+)]e and [Mg(2+)]m spectrofluorometrically in guinea pig cardiac mitochondria in response to added CaCl2 (0-0.6 mM; 1 mM EGTA buffer) with/without added MgCl2 (0-2 mM). In parallel, we assessed effects of added CaCl2 and MgCl2 on NADH, membrane potential (ΔΨm), and respiration. We found that ≥0.125 mM MgCl2 significantly attenuated CU-mediated Ca(2+) uptake and [Ca(2+)]m. Incremental [Mg(2+)]e did not reduce initial Ca(2+)uptake but attenuated the subsequent slower Ca(2+) uptake, so that [Ca(2+)]m remained unaltered over time. Adding CaCl2 without MgCl2 to attain a [Ca(2+)]m from 46 to 221 nM enhanced state 3 NADH oxidation and increased respiration by 15 %; up to 868 nM [Ca(2+)]m did not additionally enhance NADH oxidation or respiration. Adding MgCl2 did not increase [Mg(2+)]m but it altered bioenergetics by its direct effect to decrease Ca(2+) uptake. However, at a given [Ca(2+)]m, state 3 respiration was incrementally attenuated, and state 4 respiration enhanced, by higher [Mg(2+)]e. Thus, [Mg(2+)]e without a change in [Mg(2+)]m can modulate bioenergetics independently of CU-mediated Ca(2+) transport.
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Affiliation(s)
- Age D Boelens
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Wei AC, Liu T, Winslow RL, O'Rourke B. Dynamics of matrix-free Ca2+ in cardiac mitochondria: two components of Ca2+ uptake and role of phosphate buffering. ACTA ACUST UNITED AC 2013; 139:465-78. [PMID: 22641641 PMCID: PMC3362519 DOI: 10.1085/jgp.201210784] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Mitochondrial Ca(2+) uptake is thought to provide an important signal to increase energy production to meet demand but, in excess, can also trigger cell death. The mechanisms defining the relationship between total Ca(2+) uptake, changes in mitochondrial matrix free Ca(2+), and the activation of the mitochondrial permeability transition pore (PTP) are not well understood. We quantitatively measure changes in [Ca(2+)](out) and [Ca(2+)](mito) during Ca(2+) uptake in isolated cardiac mitochondria and identify two components of Ca(2+) influx. [Ca(2+)](mito) recordings revealed that the first, MCU(mode1), required at least 1 µM Ru360 to be completely inhibited, and responded to small Ca(2+) additions in the range of 0.1 to 2 µM with rapid and large changes in [Ca(2+)](mito). The second component, MCU(mode2), was blocked by 100 nM Ru360 and was responsible for the bulk of total Ca(2+) uptake for large Ca(2+) additions in the range of 2 to 10 µM; however, it had little effect on steady-state [Ca(2+)](mito). MCU(mode1) mediates changes in [Ca(2+)](mito) of 10s of μM, even in the presence of 100 nM Ru360, indicating that there is a finite degree of Ca(2+) buffering in the matrix associated with this pathway. In contrast, the much higher Ca(2+) loads evoked by MCU(mode2) activate a secondary dynamic Ca(2+) buffering system consistent with calcium-phosphate complex formation. Increasing P(i) potentiated [Ca(2+)](mito) increases via MCU(mode1) but suppressed [Ca(2+)](mito) changes via MCU(mode2). The results suggest that the role of MCU(mode1) might be to modulate oxidative phosphorylation in response to intracellular Ca(2+) signaling, whereas MCU(mode2) and the dynamic high-capacity Ca(2+) buffering system constitute a Ca(2+) sink function. Interestingly, the trigger for PTP activation is unlikely to be [Ca(2+)](mito) itself but rather a downstream byproduct of total mitochondrial Ca(2+) loading.
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Affiliation(s)
- An-Chi Wei
- Division of Cardiology, Department of Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
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Mallilankaraman K, Doonan P, Cárdenas C, Chandramoorthy HC, Müller M, Miller R, Hoffman NE, Gandhirajan RK, Molgó J, Birnbaum MJ, Rothberg BS, Mak DOD, Foskett JK, Madesh M. MICU1 is an essential gatekeeper for MCU-mediated mitochondrial Ca(2+) uptake that regulates cell survival. Cell 2013; 151:630-44. [PMID: 23101630 DOI: 10.1016/j.cell.2012.10.011] [Citation(s) in RCA: 503] [Impact Index Per Article: 45.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 07/30/2012] [Accepted: 10/05/2012] [Indexed: 12/18/2022]
Abstract
Mitochondrial Ca(2+) (Ca(2+)(m)) uptake is mediated by an inner membrane Ca(2+) channel called the uniporter. Ca(2+) uptake is driven by the considerable voltage present across the inner membrane (ΔΨ(m)) generated by proton pumping by the respiratory chain. Mitochondrial matrix Ca(2+) concentration is maintained five to six orders of magnitude lower than its equilibrium level, but the molecular mechanisms for how this is achieved are not clear. Here, we demonstrate that the mitochondrial protein MICU1 is required to preserve normal [Ca(2+)](m) under basal conditions. In its absence, mitochondria become constitutively loaded with Ca(2+), triggering excessive reactive oxygen species generation and sensitivity to apoptotic stress. MICU1 interacts with the uniporter pore-forming subunit MCU and sets a Ca(2+) threshold for Ca(2+)(m) uptake without affecting the kinetic properties of MCU-mediated Ca(2+) uptake. Thus, MICU1 is a gatekeeper of MCU-mediated Ca(2+)(m) uptake that is essential to prevent [Ca(2+)](m) overload and associated stress.
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