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Liiv M, Vaarmann A, Safiulina D, Choubey V, Gupta R, Kuum M, Janickova L, Hodurova Z, Cagalinec M, Zeb A, Hickey MA, Huang YL, Gogichaishvili N, Mandel M, Plaas M, Vasar E, Loncke J, Vervliet T, Tsai TF, Bultynck G, Veksler V, Kaasik A. ER calcium depletion as a key driver for impaired ER-to-mitochondria calcium transfer and mitochondrial dysfunction in Wolfram syndrome. Nat Commun 2024; 15:6143. [PMID: 39034309 PMCID: PMC11271478 DOI: 10.1038/s41467-024-50502-x] [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: 09/25/2023] [Accepted: 07/10/2024] [Indexed: 07/23/2024] Open
Abstract
Wolfram syndrome is a rare genetic disease caused by mutations in the WFS1 or CISD2 gene. A primary defect in Wolfram syndrome involves poor ER Ca2+ handling, but how this disturbance leads to the disease is not known. The current study, performed in primary neurons, the most affected and disease-relevant cells, involving both Wolfram syndrome genes, explains how the disturbed ER Ca2+ handling compromises mitochondrial function and affects neuronal health. Loss of ER Ca2+ content and impaired ER-mitochondrial contact sites in the WFS1- or CISD2-deficient neurons is associated with lower IP3R-mediated Ca2+ transfer from ER to mitochondria and decreased mitochondrial Ca2+ uptake. In turn, reduced mitochondrial Ca2+ content inhibits mitochondrial ATP production leading to an increased NADH/NAD+ ratio. The resulting bioenergetic deficit and reductive stress compromise the health of the neurons. Our work also identifies pharmacological targets and compounds that restore Ca2+ homeostasis, enhance mitochondrial function and improve neuronal health.
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Affiliation(s)
- Mailis Liiv
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
| | - Annika Vaarmann
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia.
| | - Dzhamilja Safiulina
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
| | - Vinay Choubey
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
| | - Ruby Gupta
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
| | - Malle Kuum
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
| | - Lucia Janickova
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Ch. du Musée 14, 1700, Fribourg, Switzerland
- Department of Cell Pharmacology and Developmental Toxicology, Institute of Experimental Pharmacology and Toxicology, Dúbravská cesta 9, 84104, Bratislava, Slovakia
| | - Zuzana Hodurova
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
- Department of Cell Pharmacology and Developmental Toxicology, Institute of Experimental Pharmacology and Toxicology, Dúbravská cesta 9, 84104, Bratislava, Slovakia
| | - Michal Cagalinec
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
- Department of Cellular Cardiology, Institute of Experimental Endocrinology, Biomedical Research Center and Centre of Excellence for Advanced Materials Application, Slovak Academy of Sciences, Dúbravská cesta 9, 84505, Bratislava, Slovakia
| | - Akbar Zeb
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
| | - Miriam A Hickey
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
| | - Yi-Long Huang
- Department of Life Sciences, Institute of Genome Sciences and Center for Healthy Longevity and Aging Sciences, National Yang Ming Chiao Tung University, 155 Li-Nong St., Section 2, Peitou, Taipei, 11221, Taiwan
| | - Nana Gogichaishvili
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
| | - Merle Mandel
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
| | - Mario Plaas
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
| | - Eero Vasar
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia
| | - Jens Loncke
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, O&N1 Herestraat 49, Leuven, Belgium
| | - Tim Vervliet
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, O&N1 Herestraat 49, Leuven, Belgium
| | - Ting-Fen Tsai
- Department of Life Sciences, Institute of Genome Sciences and Center for Healthy Longevity and Aging Sciences, National Yang Ming Chiao Tung University, 155 Li-Nong St., Section 2, Peitou, Taipei, 11221, Taiwan
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, O&N1 Herestraat 49, Leuven, Belgium
| | - Vladimir Veksler
- Laboratory of Signaling and Cardiovascular Pathophysiology, Université Paris-Saclay, Inserm, UMR-S 1180, 91400, Orsay, France
| | - Allen Kaasik
- Departments of Pharmacology and Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411, Tartu, Estonia.
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Graff SM, Nakhe AY, Dadi PK, Dickerson MT, Dobson JR, Zaborska KE, Ibsen CE, Butterworth RB, Vierra NC, Jacobson DA. TALK-1-mediated alterations of β-cell mitochondrial function and insulin secretion impair glucose homeostasis on a diabetogenic diet. Cell Rep 2024; 43:113673. [PMID: 38206814 PMCID: PMC10961926 DOI: 10.1016/j.celrep.2024.113673] [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: 11/27/2022] [Revised: 11/08/2023] [Accepted: 01/01/2024] [Indexed: 01/13/2024] Open
Abstract
Mitochondrial Ca2+ ([Ca2+]m) homeostasis is critical for β-cell function and becomes disrupted during the pathogenesis of diabetes. [Ca2+]m uptake is dependent on elevations in cytoplasmic Ca2+ ([Ca2+]c) and endoplasmic reticulum Ca2+ ([Ca2+]ER) release, both of which are regulated by the two-pore domain K+ channel TALK-1. Here, utilizing a novel β-cell TALK-1-knockout (β-TALK-1-KO) mouse model, we found that TALK-1 limited β-cell [Ca2+]m accumulation and ATP production. However, following exposure to a high-fat diet (HFD), ATP-linked respiration, glucose-stimulated oxygen consumption rate, and glucose-stimulated insulin secretion (GSIS) were increased in control but not TALK1-KO mice. Although β-TALK-1-KO animals showed similar GSIS before and after HFD treatment, these mice were protected from HFD-induced glucose intolerance. Collectively, these data identify that TALK-1 channel control of β-cell function reduces [Ca2+]m and suggest that metabolic remodeling in diabetes drives dysglycemia.
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Affiliation(s)
- Sarah M Graff
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA; Department of Pharmacy and Pharmaceutical Sciences, Lipscomb University, Nashville, TN 37204, USA
| | - Arya Y Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Jordyn R Dobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Karolina E Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Chloe E Ibsen
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Regan B Butterworth
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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Li Y, Costiniti V, Souza Bomfim GH, Neginskaya M, Son GY, Rothermel B, Pavlov E, Lacruz RS. Overexpression of RCAN1, a Gene on Human Chromosome 21, Alters Cell Redox and Mitochondrial Function in Enamel Cells. Cells 2022; 11:3576. [PMID: 36429004 PMCID: PMC9688881 DOI: 10.3390/cells11223576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/04/2022] [Accepted: 11/07/2022] [Indexed: 11/16/2022] Open
Abstract
The regulator of calcineurin (RCAN1) has been implicated in the pathogenesis of Down syndrome (DS). Individuals with DS show dental abnormalities for unknown reasons, and RCAN1 levels have been found to be elevated in several tissues of DS patients. A previous microarray analysis comparing cells of the two main formative stages of dental enamel, secretory and maturation, showed a significant increase in RCAN1 expression in the latter. Because the function of RCAN1 during enamel formation is unknown, there is no mechanistic evidence linking RCAN1 with the dental anomalies in individuals with DS. We investigated the role of RCAN1 in enamel by overexpressing RCAN1 in the ameloblast cell line LS8 (LS8+RCAN1). We first confirmed that RCAN1 is highly expressed in maturation stage ameloblasts by qRT-PCR and used immunofluorescence to show its localization in enamel-forming ameloblasts. We then analyzed cell redox and mitochondrial bioenergetics in LS8+RCAN1 cells because RCAN1 is known to impact these processes. We show that LS8+RCAN1 cells have increased reactive oxygen species (ROS) and decreased mitochondrial bioenergetics without changes in the expression of the complexes of the electron transport chain, or in NADH levels. However, LS8+RCAN1 cells showed elevated mitochondrial Ca2+ uptake and decreased expression of several enamel genes essential for enamel formation. These results provide insight into the role of RCAN1 in enamel and suggest that increased RCAN1 levels in the ameloblasts of individuals with DS may impact enamel formation by altering both the redox environment and mitochondrial function, as well as decreasing the expression of enamel-specific genes.
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Affiliation(s)
- Yi Li
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA
| | - Veronica Costiniti
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA
| | - Guilherme H. Souza Bomfim
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA
| | - Maria Neginskaya
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA
| | - Ga-Yeon Son
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA
| | - Beverly Rothermel
- Department of Internal Medicine and Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Evgeny Pavlov
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA
| | - Rodrigo S. Lacruz
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA
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Lan T, Zhang K, Lin F, He Q, Wu S, Xu Z, Zhang Y, Quan F. Effects of MICU1-Mediated Mitochondrial Calcium Uptake on Energy Metabolism and Quality of Vitrified-Thawed Mouse Metaphase II Oocytes. Int J Mol Sci 2022; 23:ijms23158629. [PMID: 35955764 PMCID: PMC9368797 DOI: 10.3390/ijms23158629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 12/10/2022] Open
Abstract
Background: Oocyte vitrification has been widely used in the treatment of infertility and fertility preservation. However, vitrification-induced mitochondrial damage adversely affects oocyte development. Several studies have reported that mitochondrial calcium uptake protein 1 (MICU1) regulates the uptake of mitochondrial calcium by the mitochondrial calcium uniporter (MCU) and subsequently controls aerobic metabolism and oxidative stress in mitochondria, but research considering oocytes remains unreported. We evaluated whether the addition of MICU1 modulators enhances mitochondrial activity, pyruvate metabolism, and developmental competence after warming of MII oocytes. Methods: Retrieved MII oocytes of mice were classified as vitrified or control groups. After thawing, oocytes of vitrified group were cultured with or without DS16570511 (MICU1 inhibitor) and MCU-i4 (MICU1 activator) for 2 h. Results: Mitochondrial Ca2+ concentration, pyruvate dephosphorylation level, and MICU1 expression of MII oocytes were significantly increased after vitrification. These phenomena were further exacerbated by the addition of MCU-i4 and reversed by the addition of DS16570511 after warming. However, the mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) in vitrified-warmed MII oocytes drop significantly after vitrification, which was improved after MCU-i4 treatment and decreased significantly after DS16570511 treatment. The vitrification process was able to elicit a development competence reduction. After parthenogenetic activation, incubation of the thawed oocytes with MCU-i4 did not alter the cleavage and blastocyst rates. Moreover, incubation of the thawed oocytes with DS16570511 reduced the cleavage and blastocyst rates. Conclusions: MICU1-mediated increasing mitochondrial calcium uptake after vitrification of the MII oocytes promoted the pyruvate oxidation, and this process may maintain oocyte development competence by compensating for the consumption of ATP under stress state.
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Wilson RJ, Lyons SP, Koves TR, Bryson VG, Zhang H, Li T, Crown SB, Ding JD, Grimsrud PA, Rosenberg PB, Muoio DM. Disruption of STIM1-mediated Ca 2+ sensing and energy metabolism in adult skeletal muscle compromises exercise tolerance, proteostasis, and lean mass. Mol Metab 2022; 57:101429. [PMID: 34979330 PMCID: PMC8814391 DOI: 10.1016/j.molmet.2021.101429] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/22/2021] [Accepted: 12/28/2021] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE Stromal interaction molecule 1 (STIM1) is a single-pass transmembrane endoplasmic/sarcoplasmic reticulum (E/SR) protein recognized for its role in a store operated Ca2+ entry (SOCE), an ancient and ubiquitous signaling pathway. Whereas STIM1 is known to be indispensable during development, its biological and metabolic functions in mature muscles remain unclear. METHODS Conditional and tamoxifen inducible muscle STIM1 knock-out mouse models were coupled with multi-omics tools and comprehensive physiology to understand the role of STIM1 in regulating SOCE, mitochondrial quality and bioenergetics, and whole-body energy homeostasis. RESULTS This study shows that STIM1 is abundant in adult skeletal muscle, upregulated by exercise, and is present at SR-mitochondria interfaces. Inducible tissue-specific deletion of STIM1 (iSTIM1 KO) in adult muscle led to diminished lean mass, reduced exercise capacity, and perturbed fuel selection in the settings of energetic stress, without affecting whole-body glucose tolerance. Proteomics and phospho-proteomics analyses of iSTIM1 KO muscles revealed molecular signatures of low-grade E/SR stress and broad activation of processes and signaling networks involved in proteostasis. CONCLUSION These results show that STIM1 regulates cellular and mitochondrial Ca2+ dynamics, energy metabolism and proteostasis in adult skeletal muscles. Furthermore, these findings provide insight into the pathophysiology of muscle diseases linked to disturbances in STIM1-dependent Ca2+ handling.
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Affiliation(s)
- Rebecca J Wilson
- Duke Molecular Physiology Institute, and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, NC 27701, USA
| | - Scott P Lyons
- Duke Molecular Physiology Institute, and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, NC 27701, USA
| | - Timothy R Koves
- Duke Molecular Physiology Institute, and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, NC 27701, USA; Department of Medicine, Division of Geriatrics, Duke University School of Medicine, Durham, NC 27705, USA
| | - Victoria G Bryson
- Duke Molecular Physiology Institute, and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, NC 27701, USA; Department of Medicine, Division of Cardiology, Duke University School of Medicine, Durham, NC 27705, USA
| | - Hengtao Zhang
- Duke Molecular Physiology Institute, and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, NC 27701, USA; Department of Medicine, Division of Cardiology, Duke University School of Medicine, Durham, NC 27705, USA
| | - TianYu Li
- Duke Molecular Physiology Institute, and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, NC 27701, USA; Department of Medicine, Division of Cardiology, Duke University School of Medicine, Durham, NC 27705, USA
| | - Scott B Crown
- Duke Molecular Physiology Institute, and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, NC 27701, USA
| | - Jin-Dong Ding
- Department of Medicine, Division of Ophthalmology, Duke University School of Medicine, Durham, NC 27705, USA
| | - Paul A Grimsrud
- Duke Molecular Physiology Institute, and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, NC 27701, USA; Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University School of Medicine, Durham, NC 27705, USA
| | - Paul B Rosenberg
- Duke Molecular Physiology Institute, and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, NC 27701, USA; Department of Medicine, Division of Cardiology, Duke University School of Medicine, Durham, NC 27705, USA
| | - Deborah M Muoio
- Duke Molecular Physiology Institute, and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, NC 27701, USA; Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University School of Medicine, Durham, NC 27705, USA; Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27705, USA.
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Killilea DW, Killilea AN. Mineral requirements for mitochondrial function: A connection to redox balance and cellular differentiation. Free Radic Biol Med 2022; 182:182-191. [PMID: 35218912 DOI: 10.1016/j.freeradbiomed.2022.02.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 02/16/2022] [Accepted: 02/21/2022] [Indexed: 12/20/2022]
Abstract
Professor Bruce Ames demonstrated that nutritional recommendations should be adjusted in order to 'tune-up' metabolism and reduce mitochondria decay, a hallmark of aging and many disease processes. A major subset of tunable nutrients are the minerals, which despite being integral to every aspect of metabolism are often deficient in the typical Western diet. Mitochondria are particularly rich in minerals, where they function as essential cofactors for mitochondrial physiology and overall cellular health. Yet substantial knowledge gaps remain in our understanding of the form and function of these minerals needed for metabolic harmony. Some of the minerals have known activities in the mitochondria but with incomplete regulatory detail, whereas other minerals have no established mitochondrial function at all. A comprehensive metallome of the mitochondria is needed to fully understand the patterns and relationships of minerals within metabolic processes and cellular development. This brief overview serves to highlight the current progress towards understanding mineral homeostasis in the mitochondria and to encourage more research activity in key areas. Future work may likely reveal that adjusting the amounts of specific nutritional minerals has longevity benefits for human health.
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Affiliation(s)
- David W Killilea
- Office of Research, University of California, San Francisco, CA, USA.
| | - Alison N Killilea
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, USA
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Hernández-Juárez C, Flores-Cruz R, Jiménez-Sánchez A. Fluorescent probe for early mitochondrial voltage dynamics. Chem Commun (Camb) 2021; 57:5526-5529. [PMID: 33956917 DOI: 10.1039/d1cc01944a] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mitochondrial voltage dynamics plays a crucial role in cell healthy and disease. Here, a new fluorescent probe to monitor mitochondrial early voltage variations is described. The slowly permeant probe is retained in mitochondria during measurements to avoid interferences from natural membrane potential by incorporating an hydrolizable ester function. Voltage, local polarity, pH parameters and transmembrane dynamics were found to be deeply correlated opening a approach in mitochondrial sensing.
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Affiliation(s)
- Cinthia Hernández-Juárez
- Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Circuito Exterior s/n, De. Coyoacán 04510, Ciudad de México, Mexico.
| | - Ricardo Flores-Cruz
- Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Circuito Exterior s/n, De. Coyoacán 04510, Ciudad de México, Mexico.
| | - Arturo Jiménez-Sánchez
- Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Circuito Exterior s/n, De. Coyoacán 04510, Ciudad de México, Mexico.
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Klier PEZ, Martin JG, Miller EW. Imaging Reversible Mitochondrial Membrane Potential Dynamics with a Masked Rhodamine Voltage Reporter. J Am Chem Soc 2021; 143:4095-4099. [PMID: 33710896 DOI: 10.1021/jacs.0c13110] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mitochondria are the site of aerobic respiration, producing ATP via oxidative phosphorylation as protons flow down their electrochemical gradient through ATP synthase. This negative membrane potential across the inner mitochondrial membrane (ΔΨm) represents a fundamental biophysical parameter central to cellular life. Traditional, electrode-based methods for recording membrane potential are impossible to implement on mitochondria within intact cells. Fluorescent ΔΨm indicators based on cationic, lipophilic dyes are a common alternative, but these indicators are complicated by concentration-dependent artifacts and the requirement to maintain dye in the extracellular solution to visualize reversible ΔΨm dynamics. Here, we report the first example of a fluorescent ΔΨm reporter that does not rely on ΔΨm-dependent accumulation. We redirected the localization of a photoinduced electron transfer (PeT)-based indicator, Rhodamine Voltage Reporter (RhoVR), to mitochondria by masking the carboxylate of RhoVR 1 as an acetoxymethyl (AM) ester. Once within mitochondria, esterases remove the AM ester, trapping RhoVR inside of the mitochondrial matrix, where it can incorporate within the inner membrane and reversibly report on changes in ΔΨm. We show that this Small molecule, Permeable, Internally Redistributing for Inner membrane Targeting Rhodamine Voltage Reporter, or SPIRIT RhoVR, localizes to mitochondria across a number of different cell lines and responds reversibly to changes in ΔΨm induced by exceptionally low concentrations of the uncoupler FCCP without the need for exogenous pools of dye (unlike traditional, accumulation-based rhodamine esters). SPIRIT RhoVR is compatible with multi-color imaging, enabling simultaneous, real-time observation of cytosolic Ca2+, plasma membrane potential, and reversible ΔΨm dynamics.
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Mitochondrial Carriers Regulating Insulin Secretion Profiled in Human Islets upon Metabolic Stress. Biomolecules 2020; 10:biom10111543. [PMID: 33198243 PMCID: PMC7697104 DOI: 10.3390/biom10111543] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/28/2020] [Accepted: 11/10/2020] [Indexed: 12/27/2022] Open
Abstract
Chronic exposure of β-cells to nutrient-rich metabolic stress impairs mitochondrial metabolism and its coupling to insulin secretion. We exposed isolated human islets to different metabolic stresses for 3 days: 0.4 mM oleate or 0.4 mM palmitate at physiological 5.5 mM glucose (lipotoxicity), high 25 mM glucose (glucotoxicity), and high 25 mM glucose combined with 0.4 mM oleate and/or palmitate (glucolipotoxicity). Then, we profiled the mitochondrial carriers and associated genes with RNA-Seq. Diabetogenic conditions, and in particular glucotoxicity, increased expression of several mitochondrial solute carriers in human islets, such as the malate carrier DIC, the α-ketoglutarate-malate exchanger OGC, and the glutamate carrier GC1. Glucotoxicity also induced a general upregulation of the electron transport chain machinery, while palmitate largely counteracted this effect. Expression of different components of the TOM/TIM mitochondrial protein import system was increased by glucotoxicity, whereas glucolipotoxicity strongly upregulated its receptor subunit TOM70. Expression of the mitochondrial calcium uniporter MCU was essentially preserved by metabolic stresses. However, glucotoxicity altered expression of regulatory elements of calcium influx as well as the Na+/Ca2+ exchanger NCLX, which mediates calcium efflux. Overall, the expression profile of mitochondrial carriers and associated genes was modified by the different metabolic stresses exhibiting nutrient-specific signatures.
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Saliakoura M, Rossi Sebastiano M, Pozzato C, Heidel FH, Schnöder TM, Savic Prince S, Bubendorf L, Pinton P, A Schmid R, Baumgartner J, Freigang S, Berezowska SA, Rimessi A, Konstantinidou G. PLCγ1 suppression promotes the adaptation of KRAS-mutant lung adenocarcinomas to hypoxia. Nat Cell Biol 2020; 22:1382-1395. [PMID: 33077911 PMCID: PMC7610419 DOI: 10.1038/s41556-020-00592-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 09/15/2020] [Indexed: 12/25/2022]
Abstract
Mutant KRAS modulates the metabolic plasticity of cancer cells conferring growth advantage during hypoxia, but the molecular underpinnings are largely unknown. Using a lipidomic screen, we found that PLCγ1 is suppressed during hypoxia in KRAS-mutant human lung adenocarcinoma cancer cell lines. Suppression of PLCγ1 in hypoxia promotes a less oxidative cancer cell metabolism, reduces the formation of mitochondrial reactive oxygen species and switches tumor bioenergetics towards glycolysis by impairing Ca2+ entry into the mitochondria. This event prevents lipid peroxidation, antagonizes apoptosis and increases cancer cell proliferation. Accordingly, loss-of-function of Plcγ1 in a mouse model of KrasG12D-driven lung adenocarcinoma increased the expression of glycolytic genes, boosted tumor growth and reduced survival. In patients with mutant KRAS lung adenocarcinomas, low PLCγ1 expression correlates with increased expression of hypoxia markers and predicts poor patient survival. Thus, our work reveals a mechanism of cancer cell adaptation to hypoxia with potential therapeutic value.
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Affiliation(s)
- Maria Saliakoura
- Institute of Pharmacology, University of Bern, Bern, Switzerland
| | | | - Chiara Pozzato
- Institute of Pharmacology, University of Bern, Bern, Switzerland
| | - Florian H Heidel
- Internal Medicine II, Hematology and Oncology, University Hospital Jena, Jena, Germany.,Leibniz-Institute on Aging, Fritz-Lipmann-Institute, Jena, Jena, Germany
| | - Tina M Schnöder
- Internal Medicine II, Hematology and Oncology, University Hospital Jena, Jena, Germany.,Leibniz-Institute on Aging, Fritz-Lipmann-Institute, Jena, Jena, Germany
| | | | - Lukas Bubendorf
- Institute of Pathology, University Hospital Basel, Basel, Switzerland
| | - Paolo Pinton
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Ralph A Schmid
- Department of General Thoracic Surgery, Inselspital, Bern, Switzerland
| | | | - Stefan Freigang
- Institute of Pathology, University of Bern, Bern, Switzerland
| | | | - Alessandro Rimessi
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
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Wu S, Lu Q, Ding Y, Wu Y, Qiu Y, Wang P, Mao X, Huang K, Xie Z, Zou MH. Hyperglycemia-Driven Inhibition of AMP-Activated Protein Kinase α2 Induces Diabetic Cardiomyopathy by Promoting Mitochondria-Associated Endoplasmic Reticulum Membranes In Vivo. Circulation 2020; 139:1913-1936. [PMID: 30646747 DOI: 10.1161/circulationaha.118.033552] [Citation(s) in RCA: 163] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Fundc1 (FUN14 domain containing 1), an outer mitochondrial membrane protein, is important for mitophagy and mitochondria-associated endoplasmic reticulum membranes (MAMs). The roles of Fundc1 and MAMs in diabetic hearts remain unknown. The aims of this study, therefore, were to determine whether the diabetes mellitus-induced Fundc1 expression could increase MAM formation, and whether disruption of MAM formation improves diabetic cardiac function. METHODS Levels of FUNDC1 were examined in the hearts from diabetic patients and nondiabetic donors. Levels of Fundc1-induced MAMs and mitochondrial and heart function were examined in mouse neonatal cardiomyocytes exposed to high glucose (HG, 30 mmol/L d-glucose for 48 hours), and in streptozotocin-treated cardiac-specific Fundc1 knockout mice and cardiac-specific Fundc1 knockout diabetic Akita mice, as well. RESULTS FUNDC1 levels were significantly elevated in cardiac tissues from diabetic patients in comparison with those from nondiabetic donors. In cultured mouse neonatal cardiomyocytes, HG conditions increased levels of Fundc1, the inositol 1,4,5-trisphosphate type 2 receptor (Ip3r2), and MAMs. Genetic downregulation of either Fundc1 or Ip3r2 inhibited MAM formation, reduced endoplasmic reticulum-mitochondrial Ca2+ flux, and improved mitochondrial function in HG-treated cardiomyocytes. Consistently, adenoviral overexpression of Fundc1 promoted MAM formation, mitochondrial Ca2+ increase, and mitochondrial dysfunction in cardiomyocytes exposed to normal glucose (5.5 mmol/L d-glucose). In comparison with nondiabetic controls, levels of Fundc1, Ip3r2, and MAMs were significantly increased in hearts from streptozotocin-treated mice and Akita mice. Furthermore, in comparison with control hearts, diabetes mellitus markedly increased coimmunoprecipitation of Fundc1 and Ip3r2. The binding of Fundc1 to Ip3r2 inhibits Ip3r2 ubiquitination and proteasome-mediated degradation. Cardiomyocyte-specific Fundc1 deletion ablated diabetes mellitus-induced MAM formation, prevented mitochondrial Ca2+ increase, mitochondrial fragmentation, and apoptosis with improved mitochondrial functional capacity and cardiac function. In mouse neonatal cardiomyocytes, HG suppressed AMP-activated protein kinase activity. Furthermore, in cardiomyocytes of Prkaa2 knockout mice, expression of Fundc1, MAM formation, and mitochondrial Ca2+ levels were significantly increased. Finally, adenoviral overexpression of a constitutively active mutant AMP-activated protein kinase ablated HG-induced MAM formation and mitochondrial dysfunction. CONCLUSIONS We conclude that diabetes mellitus suppresses AMP-activated protein kinase, initiating Fundc1-mediated MAM formation, mitochondrial dysfunction, and cardiomyopathy, suggesting that AMP-activated protein kinase-induced Fundc1 suppression is a valid target to treat diabetic cardiomyopathy.
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Affiliation(s)
- Shengnan Wu
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Qiulun Lu
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Ye Ding
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Yin Wu
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Yu Qiu
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Pei Wang
- Mitochondria and Metabolism Center, University of Washington, Seattle (P.W.)
| | - Xiaoxiang Mao
- Wuhan Union Hospital, Huazhong University of Science and Technology, Hubei, China (Z.M., K.H.)
| | - Kai Huang
- Wuhan Union Hospital, Huazhong University of Science and Technology, Hubei, China (Z.M., K.H.)
| | - Zhonglin Xie
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Ming-Hui Zou
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
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Romero-Garcia S, Prado-Garcia H. Mitochondrial calcium: Transport and modulation of cellular processes in homeostasis and cancer (Review). Int J Oncol 2019; 54:1155-1167. [PMID: 30720054 DOI: 10.3892/ijo.2019.4696] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 12/06/2018] [Indexed: 11/05/2022] Open
Abstract
In addition to their role in providing cellular energy, mitochondria fulfill a key function in cellular calcium management. The present review provides an integrative view of cellular and mitochondrial calcium homeostasis, and discusses how calcium regulates mitochondrial dynamics and functionality, thus affecting various cellular processes. Calcium crosstalk exists in the domain created between the endoplasmic reticulum and mitochondria, which is known as the mitochondria‑associated membrane (MAM), and controls cellular homeostasis. Calcium signaling participates in numerous biochemical and cellular processes, where calcium concentration, temporality and durability are part of a regulated, finely tuned interplay in non‑transformed cells. In addition, cancer cells modify their MAMs, which consequently affects calcium homeostasis to support mesenchymal transformation, migration, invasiveness, metastasis and autophagy. Alterations in calcium homeostasis may also support resistance to apoptosis, which is a serious problem facing current chemotherapeutic treatments. Notably, mitochondrial dynamics are also affected by mitochondrial calcium concentration to promote cancer survival responses. Dysregulated levels of mitochondrial calcium, alongside other signals, promote mitoflash generation in tumor cells, and an increased frequency of mitoflashes may induce epithelial‑to‑mesenchymal transition. Therefore, cancer cells remodel their calcium balance through numerous mechanisms that support their survival and growth.
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Affiliation(s)
- Susana Romero-Garcia
- Department of Chronic-Degenerative Diseases, National Institute of Respiratory Diseases 'Ismael Cosío Villegas', CP 14080 Mexico City, Mexico
| | - Heriberto Prado-Garcia
- Department of Chronic-Degenerative Diseases, National Institute of Respiratory Diseases 'Ismael Cosío Villegas', CP 14080 Mexico City, Mexico
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13
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Hou QZ, Sun K, Zhang H, Su X, Fan BQ, Feng HQ. The responses of photosystem II and intracellular ATP production of Arabidopsis leaves to salt stress are affected by extracellular ATP. JOURNAL OF PLANT RESEARCH 2018; 131:331-339. [PMID: 29098479 DOI: 10.1007/s10265-017-0990-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 09/28/2017] [Indexed: 05/16/2023]
Abstract
Hypertonic salt stress with different concentrations of NaCl increased the levels of extracellular ATP of Arabidopsis leaves. And, hypertonic salt stress decreased the levels of F v /F m (the maximal efficiency of photosystem II), Φ PSII (the photosystem II operating efficiency), qP (photochemical quenching), and intracellular ATP (iATP) production. The treatment with β,γ-methyleneadenosine 5'-triphosphate (AMP-PCP), which can exclude extracellular ATP from its binding sites of extracellular ATP receptors, caused a further decrease in the levels of F v /F m , Φ PSII, qP, and iATP production of the salt-stressed Arabidopsis leaves, while the addition of exogenous ATP rescued the inhibitory effects of AMP-PCP on Φ PSII , qP, and iATP production under hypertonic salt stress. Under hypertonic salt stress, the values of F v /F m , Φ PSII , qP, and iATP production were lower in the dorn 1-3 mutant than in the wild-type plants. These results indicate that the responses of photosystem II and intracellular ATP production to salt stress could be affected by extracellular ATP.
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Affiliation(s)
- Qin-Zheng Hou
- Department of Biology Science, College of Life Sciences, Northwest Normal University, Anning East Road, Lanzhou, 730070, Gansu, China
| | - Kun Sun
- Department of Biology Science, College of Life Sciences, Northwest Normal University, Anning East Road, Lanzhou, 730070, Gansu, China
| | - Hui Zhang
- Department of Biology Science, College of Life Sciences, Northwest Normal University, Anning East Road, Lanzhou, 730070, Gansu, China
| | - Xue Su
- Department of Biology Science, College of Life Sciences, Northwest Normal University, Anning East Road, Lanzhou, 730070, Gansu, China
| | - Bao-Qiang Fan
- Department of Biology Science, College of Life Sciences, Northwest Normal University, Anning East Road, Lanzhou, 730070, Gansu, China
| | - Han-Qing Feng
- Department of Biology Science, College of Life Sciences, Northwest Normal University, Anning East Road, Lanzhou, 730070, Gansu, China.
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Cheung LTY, Manthey AL, Lai JSM, Chiu K. Targeted Delivery of Mitochondrial Calcium Channel Regulators: The Future of Glaucoma Treatment? Front Neurosci 2017; 11:648. [PMID: 29213227 PMCID: PMC5702640 DOI: 10.3389/fnins.2017.00648] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/07/2017] [Indexed: 11/18/2022] Open
Affiliation(s)
- Leanne T Y Cheung
- Department of Ophthalmology, University of Hong Kong, Hong Kong, China
| | - Abby L Manthey
- Department of Ophthalmology, University of Hong Kong, Hong Kong, China
| | - Jimmy S M Lai
- Department of Ophthalmology, University of Hong Kong, Hong Kong, China
| | - Kin Chiu
- Department of Ophthalmology, University of Hong Kong, Hong Kong, China
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Morais MAB, Giuseppe PO, Souza TACB, Castro H, Honorato RV, Oliveira PSL, Netto LES, Tomas AM, Murakami MT. Calcium and magnesium ions modulate the oligomeric state and function of mitochondrial 2-Cys peroxiredoxins in Leishmania parasites. J Biol Chem 2017; 292:7023-7039. [PMID: 28292930 PMCID: PMC5409470 DOI: 10.1074/jbc.m116.762039] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 03/07/2017] [Indexed: 12/16/2022] Open
Abstract
Leishmania parasites have evolved a number of strategies to cope with the harsh environmental changes during mammalian infection. One of these mechanisms involves the functional gain that allows mitochondrial 2-Cys peroxiredoxins to act as molecular chaperones when forming decamers. This function is critical for parasite infectivity in mammals, and its activation has been considered to be controlled exclusively by the enzyme redox state under physiological conditions. Herein, we have revealed that magnesium and calcium ions play a major role in modulating the ability of these enzymes to act as molecular chaperones, surpassing the redox effect. These ions are directly involved in mitochondrial metabolism and participate in a novel mechanism to stabilize the decameric form of 2-Cys peroxiredoxins in Leishmania mitochondria. Moreover, we have demonstrated that a constitutively dimeric Prx1m mutant impairs the survival of Leishmania under heat stress, supporting the central role of the chaperone function of Prx1m for Leishmania parasites during the transition from insect to mammalian hosts.
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Affiliation(s)
- Mariana A B Morais
- From the Biosciences National Laboratory, National Center for Research in Energy and Materials, Rua Giuseppe Maximo Scolfaro 10000, 13083-100 Campinas/SP, Brazil
| | - Priscila O Giuseppe
- From the Biosciences National Laboratory, National Center for Research in Energy and Materials, Rua Giuseppe Maximo Scolfaro 10000, 13083-100 Campinas/SP, Brazil
| | - Tatiana A C B Souza
- the Proteomics and Protein Engineering Laboratory, Carlos Chagas Institute, Fiocruz, Rua Professor Algacyr Munhoz Mader 2135, 81310-020 Curitiba/PR, Brazil
| | - Helena Castro
- the i3S-Institute for Investigation and Innovation in Health, University of Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- the Institute of Molecular and Cell Biology (IBMC), University of Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Rodrigo V Honorato
- From the Biosciences National Laboratory, National Center for Research in Energy and Materials, Rua Giuseppe Maximo Scolfaro 10000, 13083-100 Campinas/SP, Brazil
| | - Paulo S L Oliveira
- From the Biosciences National Laboratory, National Center for Research in Energy and Materials, Rua Giuseppe Maximo Scolfaro 10000, 13083-100 Campinas/SP, Brazil
| | - Luis E S Netto
- the Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of the State of São Paulo, Rua do Matão 14, 05508-090 São Paulo/SP, Brazil, and
| | - Ana M Tomas
- the i3S-Institute for Investigation and Innovation in Health, University of Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- the Institute of Molecular and Cell Biology (IBMC), University of Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- the Abel Salazar Biomedical Sciences Institute, University of Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal
| | - Mario T Murakami
- From the Biosciences National Laboratory, National Center for Research in Energy and Materials, Rua Giuseppe Maximo Scolfaro 10000, 13083-100 Campinas/SP, Brazil,
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16
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Kannurpatti SS. Mitochondrial calcium homeostasis: Implications for neurovascular and neurometabolic coupling. J Cereb Blood Flow Metab 2017; 37:381-395. [PMID: 27879386 PMCID: PMC5381466 DOI: 10.1177/0271678x16680637] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mitochondrial function is critical to maintain high rates of oxidative metabolism supporting energy demands of both spontaneous and evoked neuronal activity in the brain. Mitochondria not only regulate energy metabolism, but also influence neuronal signaling. Regulation of "energy metabolism" and "neuronal signaling" (i.e. neurometabolic coupling), which are coupled rather than independent can be understood through mitochondria's integrative functions of calcium ion (Ca2+) uptake and cycling. While mitochondrial Ca2+ do not affect hemodynamics directly, neuronal activity changes are mechanistically linked to functional hyperemic responses (i.e. neurovascular coupling). Early in vitro studies lay the foundation of mitochondrial Ca2+ homeostasis and its functional roles within cells. However, recent in vivo approaches indicate mitochondrial Ca2+ homeostasis as maintained by the role of mitochondrial Ca2+ uniporter (mCU) influences system-level brain activity as measured by a variety of techniques. Based on earlier evidence of subcellular cytoplasmic Ca2+ microdomains and cellular bioenergetic states, a mechanistic model of Ca2+ mobilization is presented to understand systems-level neurovascular and neurometabolic coupling. This integrated view from molecular and cellular to the systems level, where mCU plays a major role in mitochondrial and cellular Ca2+ homeostasis, may explain the wide range of activation-induced coupling across neuronal activity, hemodynamic, and metabolic responses.
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17
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Hrynevich SV, Waseem TV, Fedorovich SV. Estimation of the mitochondrial calcium pool in rat brain synaptosomes using Rhod-2 AM fluorescent dye. Biophysics (Nagoya-shi) 2017. [DOI: 10.1134/s0006350917010079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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19
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Abstract
In the last 5 years, most of the molecules that control mitochondrial Ca(2+) homeostasis have been finally identified. Mitochondrial Ca(2+) uptake is mediated by the Mitochondrial Calcium Uniporter (MCU) complex, a macromolecular structure that guarantees Ca(2+) accumulation inside mitochondrial matrix upon increases in cytosolic Ca(2+). Conversely, Ca(2+) release is under the control of the Na(+)/Ca(2+) exchanger, encoded by the NCLX gene, and of a H(+)/Ca(2+) antiporter, whose identity is still debated. The low affinity of the MCU complex, coupled to the activity of the efflux systems, protects cells from continuous futile cycles of Ca(2+) across the inner mitochondrial membrane and consequent massive energy dissipation. In this review, we discuss the basic principles that govern mitochondrial Ca(2+) homeostasis and the methods used to investigate the dynamics of Ca(2+) concentration within the organelles. We discuss the functional and structural role of the different molecules involved in mitochondrial Ca(2+) handling and their pathophysiological role.
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Affiliation(s)
- Diego De Stefani
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , ,
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , , .,National Research Council (CNR) Neuroscience Institute, 35121 Padova, Italy
| | - Tullio Pozzan
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , , .,National Research Council (CNR) Neuroscience Institute, 35121 Padova, Italy.,Venetian Institute of Molecular Medicine, 35121 Padova, Italy
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20
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Brun T, Maechler P. Beta-cell mitochondrial carriers and the diabetogenic stress response. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2540-9. [PMID: 26979549 DOI: 10.1016/j.bbamcr.2016.03.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 01/09/2023]
Abstract
Mitochondria play a central role in pancreatic beta-cells by coupling metabolism of the secretagogue glucose to distal events of regulated insulin exocytosis. This process requires transports of both metabolites and nucleotides in and out of the mitochondria. The molecular identification of mitochondrial carriers and their respective contribution to beta-cell function have been uncovered only recently. In type 2 diabetes, mitochondrial dysfunction is an early event and may precipitate beta-cell loss. Under diabetogenic conditions, characterized by glucotoxicity and lipotoxicity, the expression profile of mitochondrial carriers is selectively modified. This review describes the role of mitochondrial carriers in beta-cells and the selective changes in response to glucolipotoxicity. In particular, we discuss the importance of the transfer of metabolites (pyruvate, citrate, malate, and glutamate) and nucleotides (ATP, NADH, NADPH) for beta-cell function and dysfunction. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.
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Affiliation(s)
- Thierry Brun
- Department of Cell Physiology and Metabolism, Faculty Diabetes Center, Geneva University Medical Centre, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland
| | - Pierre Maechler
- Department of Cell Physiology and Metabolism, Faculty Diabetes Center, Geneva University Medical Centre, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland.
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21
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Posey AD, Kawalekar OU, June CH. Measurement of intracellular ions by flow cytometry. ACTA ACUST UNITED AC 2015; 72:9.8.1-9.8.21. [PMID: 25827486 DOI: 10.1002/0471142956.cy0908s72] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Using flow cytometry, single-cell measurements of calcium can be made on isolated populations identified by one or more phenotypic characteristics. Most earlier techniques for measuring cellular activation parameters determined the mean value for a population of cells, which did not permit optimal resolution of the responses. The flow cytometer is particularly useful for this purpose because it can measure ion concentrations in large numbers of single cells and thereby allows ion concentration to be correlated with other parameters such as immunophenotype and cell cycle stage. A limitation of flow cytometry, however, is that it does not permit resolution of certain complex kinetic responses such as cellular oscillatory responses. This unit describes the preparation of cells, including labeling with antibodies and with calcium probes, and discusses the principles of data analysis and interpretation.
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Affiliation(s)
- Avery D Posey
- Abramson Family Cancer Research Institute, and the Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Omkar U Kawalekar
- Abramson Family Cancer Research Institute, and the Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Carl H June
- Abramson Family Cancer Research Institute, and the Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
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22
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Hertz L, Rothman DL, Li B, Peng L. Chronic SSRI stimulation of astrocytic 5-HT2B receptors change multiple gene expressions/editings and metabolism of glutamate, glucose and glycogen: a potential paradigm shift. Front Behav Neurosci 2015; 9:25. [PMID: 25750618 PMCID: PMC4335176 DOI: 10.3389/fnbeh.2015.00025] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 01/23/2015] [Indexed: 11/13/2022] Open
Abstract
It is firmly believed that the mechanism of action of SSRIs in major depression is to inhibit the serotonin transporter, SERT, and increase extracellular concentration of serotonin. However, this undisputed observation does not prove that SERT inhibition is the mechanism, let alone the only mechanism, by which SSRI's exert their therapeutic effects. It has recently been demonstrated that 5-HT2B receptor stimulation is needed for the antidepressant effect of fluoxetine in vivo. The ability of all five currently used SSRIs to stimulate the 5-HT2B receptor equipotentially in cultured astrocytes has been known for several years, and increasing evidence has shown the importance of astrocytes and astrocyte-neuronal interactions for neuroplasticity and complex brain activity. This paper reviews acute and chronic effects of 5-HT2B receptor stimulation in cultured astrocytes and in astrocytes freshly isolated from brains of mice treated with fluoxetine for 14 days together with effects of anti-depressant therapy on turnover of glutamate and GABA and metabolism of glucose and glycogen. It is suggested that these events are causally related to the mechanism of action of SSRIs and of interest for development of newer antidepressant drugs.
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Affiliation(s)
- Leif Hertz
- Laboratory of Brain Metabolic Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University Shenyang, China
| | - Douglas L Rothman
- Magnetic Resonance Research Center, Diagnostic Radiology and Biomedical Engineering, Yale University New Haven, CT, USA
| | - Baoman Li
- Laboratory of Brain Metabolic Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University Shenyang, China
| | - Liang Peng
- Laboratory of Brain Metabolic Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University Shenyang, China
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Gilon P, Chae HY, Rutter GA, Ravier MA. Calcium signaling in pancreatic β-cells in health and in Type 2 diabetes. Cell Calcium 2014; 56:340-61. [DOI: 10.1016/j.ceca.2014.09.001] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/26/2014] [Accepted: 09/01/2014] [Indexed: 12/24/2022]
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Jaiswal MK. Selective vulnerability of motoneuron and perturbed mitochondrial calcium homeostasis in amyotrophic lateral sclerosis: implications for motoneurons specific calcium dysregulation. MOLECULAR AND CELLULAR THERAPIES 2014; 2:26. [PMID: 26056593 PMCID: PMC4452055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 07/23/2014] [Indexed: 11/21/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative disorder characterized by the selective degeneration of defined subgroups of motoneuron in the brainstem, spinal cord and motor cortex with signature hallmarks of mitochondrial Ca(2+) overload, free radical damage, excitotoxicity and impaired axonal transport. Although intracellular disruptions of cytosolic and mitochondrial calcium, and in particular low cytosolic calcium ([Ca(2+)]c) buffering and a strong interaction between metabolic mechanisms and [Ca(2+)]i have been identified predominantly in motoneuron impairment, the causes of these disruptions are unknown. The existing evidence suggests that the mutant superoxide dismutase1 (mtSOD1)-mediated toxicity in ALS acts through mitochondria, and that alteration in cytosolic and mitochondria-ER microdomain calcium accumulation are critical to the neurodegenerative process. Furthermore, chronic excitotoxcity mediated by Ca(2+)-permeable AMPA and NMDA receptors seems to initiate vicious cycle of intracellular calcium dysregulation which leads to toxic Ca(2+) overload and thereby selective neurodegeneration. Recent advancement in the experimental analysis of calcium signals with high spatiotemporal precision has allowed investigations of calcium regulation in-vivo and in-vitro in different cell types, in particular selectively vulnerable/resistant cell types in different animal models of this motoneuron disease. This review provides an overview of latest advances in this field, and focuses on details of what has been learned about disrupted Ca(2+) homeostasis and mitochondrial degeneration. It further emphasizes the critical role of mitochondria in preventing apoptosis by acting as a Ca(2+) buffers, especially in motoneurons, in pathophysiological conditions such as ALS.
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Affiliation(s)
- Manoj Kumar Jaiswal
- />Center for Neuroscience and Regenerative Medicine, 4301 Jones Bridge Road, 20814 Bethesda, MD USA
- />Department of Anatomy, Physiology and Genetics, School of Medicine, USUHS, 4301 Jones Bridge Road, 20814 Bethesda, MD USA
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25
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Jaiswal MK. Selective vulnerability of motoneuron and perturbed mitochondrial calcium homeostasis in amyotrophic lateral sclerosis: implications for motoneurons specific calcium dysregulation. MOLECULAR AND CELLULAR THERAPIES 2014; 2:26. [PMID: 26056593 PMCID: PMC4452055 DOI: 10.1186/2052-8426-2-26] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 07/23/2014] [Indexed: 02/07/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative disorder characterized by the selective degeneration of defined subgroups of motoneuron in the brainstem, spinal cord and motor cortex with signature hallmarks of mitochondrial Ca2+ overload, free radical damage, excitotoxicity and impaired axonal transport. Although intracellular disruptions of cytosolic and mitochondrial calcium, and in particular low cytosolic calcium ([Ca2+]c) buffering and a strong interaction between metabolic mechanisms and [Ca2+]i have been identified predominantly in motoneuron impairment, the causes of these disruptions are unknown. The existing evidence suggests that the mutant superoxide dismutase1 (mtSOD1)-mediated toxicity in ALS acts through mitochondria, and that alteration in cytosolic and mitochondria-ER microdomain calcium accumulation are critical to the neurodegenerative process. Furthermore, chronic excitotoxcity mediated by Ca2+-permeable AMPA and NMDA receptors seems to initiate vicious cycle of intracellular calcium dysregulation which leads to toxic Ca2+ overload and thereby selective neurodegeneration. Recent advancement in the experimental analysis of calcium signals with high spatiotemporal precision has allowed investigations of calcium regulation in-vivo and in-vitro in different cell types, in particular selectively vulnerable/resistant cell types in different animal models of this motoneuron disease. This review provides an overview of latest advances in this field, and focuses on details of what has been learned about disrupted Ca2+ homeostasis and mitochondrial degeneration. It further emphasizes the critical role of mitochondria in preventing apoptosis by acting as a Ca2+ buffers, especially in motoneurons, in pathophysiological conditions such as ALS.
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Affiliation(s)
- Manoj Kumar Jaiswal
- Center for Neuroscience and Regenerative Medicine, 4301 Jones Bridge Road, 20814 Bethesda, MD USA ; Department of Anatomy, Physiology and Genetics, School of Medicine, USUHS, 4301 Jones Bridge Road, 20814 Bethesda, MD USA
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Characterization of hydromedusan Ca2+-regulated photoproteins as a tool for measurement of Ca2+concentration. Anal Bioanal Chem 2014; 406:5715-26. [DOI: 10.1007/s00216-014-7986-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Revised: 05/30/2014] [Accepted: 06/18/2014] [Indexed: 10/25/2022]
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Studies on the regulation of the human E1 subunit of the 2-oxoglutarate dehydrogenase complex, including the identification of a novel calcium-binding site. Biochem J 2014; 459:369-81. [PMID: 24495017 DOI: 10.1042/bj20131664] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The regulation of the 2-oxoglutarate dehydrogenase complex is central to intramitochondrial energy metabolism. In the present study, the active full-length E1 subunit of the human complex has been expressed and shown to be regulated by Ca2+, adenine nucleotides and NADH, with NADH exerting a major influence on the K0.5 value for Ca2+. We investigated two potential Ca2+-binding sites on E1, which we term site 1 (D114ADLD) and site 2 (E139SDLD). Comparison of sequences from vertebrates with those from Ca2+-insensitive non-vertebrate complexes suggest that site 1 may be the more important. Consistent with this view, a mutated form of E1, D114A, shows a 6-fold decrease in sensitivity for Ca2+, whereas variant ∆site1 (in which the sequence of site 1 is replaced by A114AALA) exhibits an almost complete loss of Ca2+ activation. Variant ∆site2 (in which the sequence is replaced with A139SALA) shows no measurable change in Ca2+ sensitivity. We conclude that site 1, but not site 2, forms part of a regulatory Ca2+-binding site, which is distinct from other previously described Ca2+-binding sites.
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De Michele R, Carimi F, Frommer WB. Mitochondrial biosensors. Int J Biochem Cell Biol 2014; 48:39-44. [PMID: 24397954 DOI: 10.1016/j.biocel.2013.12.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 12/26/2013] [Indexed: 10/25/2022]
Abstract
Biosensors offer an innovative tool for measuring the dynamics of a wide range of metabolites in living organisms. Biosensors are genetically encoded, and thus can be specifically targeted to specific compartments of organelles by fusion to proteins or targeting sequences. Mitochondria are central to eukaryotic cell metabolism and present a complex structure with multiple compartments. Over the past decade, genetically encoded sensors for molecules involved in energy production, reactive oxygen species and secondary messengers have helped to unravel key aspects of mitochondrial physiology. To date, sensors for ATP, NADH, pH, hydrogen peroxide, superoxide anion, redox state, cAMP, calcium and zinc have been used in the matrix, intermembrane space and in the outer membrane region of mitochondria of animal and plant cells. This review summarizes the different types of sensors employed in mitochondria and their main limits and advantages, and it provides an outlook for the future application of biosensor technology in studying mitochondrial biology.
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Affiliation(s)
- Roberto De Michele
- Institute of Biosciences and Bioresources, National Research Council of Italy (CNR-IBBR), Corso Calatafimi 414, 90129 Palermo, Italy.
| | - Francesco Carimi
- Institute of Biosciences and Bioresources, National Research Council of Italy (CNR-IBBR), Corso Calatafimi 414, 90129 Palermo, Italy
| | - Wolf B Frommer
- Department of Plant Biology, Carnegie Institute for Science, 260 Panama Street, Stanford, CA 94305, USA
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Maechler P. Mitochondrial function and insulin secretion. Mol Cell Endocrinol 2013; 379:12-8. [PMID: 23792187 DOI: 10.1016/j.mce.2013.06.019] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 06/12/2013] [Accepted: 06/12/2013] [Indexed: 10/26/2022]
Abstract
In the endocrine fraction of the pancreas, the β-cell rapidly reacts to fluctuations in blood glucose concentrations by adjusting the rate of insulin secretion. Glucose-sensing coupled to insulin exocytosis depends on transduction of metabolic signals into intracellular messengers recognized by the secretory machinery. Mitochondria play a central role in this process by connecting glucose metabolism to insulin release. Mitochondrial activity is primarily regulated by metabolic fluxes, but also by dynamic morphology changes and free Ca(2+) concentrations. Recent advances of mitochondrial Ca(2+) homeostasis are discussed; in particular the roles of the newly-identified mitochondrial Ca(2+) uniporter MCU and its regulatory partner MICU1, as well as the mitochondrial Na(+)-Ca(2+) exchanger. This review describes how mitochondria function both as sensors and generators of metabolic signals; such as NADPH, long chain acyl-CoA, glutamate. The coupling factors are additive to the Ca(2+) signal and participate to the amplifying pathway of glucose-stimulated insulin secretion.
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Affiliation(s)
- Pierre Maechler
- Department of Cell Physiology and Metabolism, Geneva University Medical Centre, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland.
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30
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Bround MJ, Wambolt R, Luciani DS, Kulpa JE, Rodrigues B, Brownsey RW, Allard MF, Johnson JD. Cardiomyocyte ATP production, metabolic flexibility, and survival require calcium flux through cardiac ryanodine receptors in vivo. J Biol Chem 2013; 288:18975-86. [PMID: 23678000 DOI: 10.1074/jbc.m112.427062] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Ca(2+) fluxes between adjacent organelles are thought to control many cellular processes, including metabolism and cell survival. In vitro evidence has been presented that constitutive Ca(2+) flux from intracellular stores into mitochondria is required for basal cellular metabolism, but these observations have not been made in vivo. We report that controlled in vivo depletion of cardiac RYR2, using a conditional gene knock-out strategy (cRyr2KO mice), is sufficient to reduce mitochondrial Ca(2+) and oxidative metabolism, and to establish a pseudohypoxic state with increased autophagy. Dramatic metabolic reprogramming was evident at the transcriptional level via Sirt1/Foxo1/Pgc1α, Atf3, and Klf15 gene networks. Ryr2 loss also induced a non-apoptotic form of programmed cell death associated with increased calpain-10 but not caspase-3 activation or endoplasmic reticulum stress. Remarkably, cRyr2KO mice rapidly exhibited many of the structural, metabolic, and molecular characteristics of heart failure at a time when RYR2 protein was reduced 50%, a similar degree to that which has been reported in heart failure. RYR2-mediated Ca(2+) fluxes are therefore proximal controllers of mitochondrial Ca(2+), ATP levels, and a cascade of transcription factors controlling metabolism and survival.
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Affiliation(s)
- Michael J Bround
- Cardiovascular Research Group, Life Sciences Institute, University of British Columbia, Vancouver V6T 1Z3, Canada
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31
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Ottolini D, Calì T, Brini M. Measurements of Ca²⁺ concentration with recombinant targeted luminescent probes. Methods Mol Biol 2013; 937:273-91. [PMID: 23007593 DOI: 10.1007/978-1-62703-086-1_17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In the last two decades the study of Ca(2+) homeostasis in living cells has been enhanced by the explosive development of genetically encoded Ca(2+)-indicators. The cloning of the Ca(2+)-sensitive photoprotein aequorin and of the green fluorescent protein (GFP) from the jellyfish Aequorea victoria has been enormously advantageous. As polypeptides, aequorin and GFP allow their endogenous production in cell systems as diverse as bacteria, yeast, slime molds, plants, and mammalian cells. Moreover, it is possible to specifically localize them within the cell by including defined targeting signals in the amino acid sequence. These two proteins have been extensively engineered to obtain several recombinant probes for different biological parameters, among which Ca(2+) concentration reporters are probably the most relevant. The GFP-based Ca(2+) probes and aequorin are widely employed in the study of intracellular Ca(2+) homeostasis. The new generation of bioluminescent probes that couple the Ca(2+) sensitivity of aequorin to GFP fluorescence emission allows real-time measurements of subcellular Ca(2+) changes in single cell imaging experiments and the video-imaging of Ca(2+) concentrations changes in live transgenic animals that express GFP-aequorin bifunctional probes.
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Affiliation(s)
- Denis Ottolini
- Department of Biomedical Sciences, University of Padova, Padova, Italy
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Abstract
In the endocrine fraction of the pancreas, the task of the beta-cell is to continuously and perfectly adjust insulin secretion to fluctuating blood glucose levels, thereby maintaining glycemia and nutrient homeostasis. This glucose sensing coupled to insulin exocytosis depends on transduction of metabolic signals into intracellular messengers recognized by the exocytotic machinery. Central to this metabolism-secretion coupling, mitochondrial signal transduction refers to both integration and generation of metabolic signals, connecting glucose sensing to insulin exocytosis. In response to a glucose rise, nucleotides and metabolites are generated by mitochondria and participate, together with cytosolic calcium, in the stimulation of insulin release. This review describes the role of mitochondria in metabolic signal transduction regulating insulin secretion.
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Affiliation(s)
- Pierre Maechler
- Department of Cell Physiology and Metabolism, University of Geneva Medical Centre, rue Michel-Servet 1, CH-1211 Geneva 4, Switzerland.
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33
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Cardiac subsarcolemmal and interfibrillar mitochondria display distinct responsiveness to protection by diazoxide. PLoS One 2012; 7:e44667. [PMID: 22973464 PMCID: PMC3433441 DOI: 10.1371/journal.pone.0044667] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 08/09/2012] [Indexed: 01/11/2023] Open
Abstract
Objective Cardiac subsarcolemmal (SSM) and interfibrillar (IFM) mitochondrial subpopulations possess distinct biochemical properties and differ with respect to their protein and lipid compositions, capacities for respiration and protein synthesis, and sensitivity to metabolic challenge, yet their responsiveness to mitochondrially active cardioprotective therapeutics has not been characterized. This study assessed the differential responsiveness of the two mitochondrial subpopulations to diazoxide, a cardioprotective agent targeting mitochondria. Methods Mitochondrial subpopulations were freshly isolated from rat ventricles and their morphologies assessed by electron microscopy and enzymatic activities determined using standard biochemical protocols with a plate reader. Oxidative phosphorylation was assessed from State 3 respiration using succinate as a substrate. Calcium dynamics and the status of Ca2+-dependent mitochondrial permeability transition (MPT) pore and mitochondrial membrane potential were assessed using standard Ca2+ and TPP+ ion-selective electrodes. Results Compared to IFM, isolated SSM exhibited a higher sensitivity to Ca2+ overload-mediated inhibition of adenosine triphosphate (ATP) synthesis with decreased ATP production (from 375±25 to 83±15 nmol ATP/min/mg protein in SSM, and from 875±39 to 583±45 nmol ATP/min/mg protein in IFM). In addition, SSM exhibited reduced Ca2+-accumulating capacity as compared to IFM (230±13 vs. 450±46 nmol Ca2+/mg protein in SSM and IFM, respectively), suggestive of increased Ca2+ sensitivity of MPT pore opening. Despite enhanced susceptibility to stress, SSM were more responsive to the protective effect of diazoxide (100 μM) against Ca2+ overload-mediated inhibition of ATP synthesis (67% vs. 2% in SSM and IFM, respectively). Conclusion These results provide evidence for the distinct sensitivity of cardiac SSM and IFM toward Ca2+-dependent metabolic stress and the protective effect of diazoxide on mitochondrial energetics.
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Tarasov AI, Griffiths EJ, Rutter GA. Regulation of ATP production by mitochondrial Ca(2+). Cell Calcium 2012; 52:28-35. [PMID: 22502861 PMCID: PMC3396849 DOI: 10.1016/j.ceca.2012.03.003] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 03/10/2012] [Accepted: 03/14/2012] [Indexed: 01/09/2023]
Abstract
Stimulation of mitochondrial oxidative metabolism by Ca(2+) is now generally recognised as important for the control of cellular ATP homeostasis. Here, we review the mechanisms through which Ca(2+) regulates mitochondrial ATP synthesis. We focus on cardiac myocytes and pancreatic β-cells, where tight control of this process is likely to play an important role in the response to rapid changes in workload and to nutrient stimulation, respectively. We also describe a novel approach for imaging the Ca(2+)-dependent regulation of ATP levels dynamically in single cells.
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Affiliation(s)
- Andrei I Tarasov
- Section of Cell Biology, Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Imperial College London, SW7 2AZ, London, UK
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35
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Abstract
Calcium is an important signaling molecule involved in the regulation of many cellular functions. The large free energy in the Ca(2+) ion membrane gradients makes Ca(2+) signaling inherently sensitive to the available cellular free energy, primarily in the form of ATP. In addition, Ca(2+) regulates many cellular ATP-consuming reactions such as muscle contraction, exocytosis, biosynthesis, and neuronal signaling. Thus, Ca(2+) becomes a logical candidate as a signaling molecule for modulating ATP hydrolysis and synthesis during changes in numerous forms of cellular work. Mitochondria are the primary source of aerobic energy production in mammalian cells and also maintain a large Ca(2+) gradient across their inner membrane, providing a signaling potential for this molecule. The demonstrated link between cytosolic and mitochondrial Ca(2+) concentrations, identification of transport mechanisms, and the proximity of mitochondria to Ca(2+) release sites further supports the notion that Ca(2+) can be an important signaling molecule in the energy metabolism interplay of the cytosol with the mitochondria. Here we review sites within the mitochondria where Ca(2+) plays a role in the regulation of ATP generation and potentially contributes to the orchestration of cellular metabolic homeostasis. Early work on isolated enzymes pointed to several matrix dehydrogenases that are stimulated by Ca(2+), which were confirmed in the intact mitochondrion as well as cellular and in vivo systems. However, studies in these intact systems suggested a more expansive influence of Ca(2+) on mitochondrial energy conversion. Numerous noninvasive approaches monitoring NADH, mitochondrial membrane potential, oxygen consumption, and workloads suggest significant effects of Ca(2+) on other elements of NADH generation as well as downstream elements of oxidative phosphorylation, including the F(1)F(O)-ATPase and the cytochrome chain. These other potential elements of Ca(2+) modification of mitochondrial energy conversion will be the focus of this review. Though most specific molecular mechanisms have yet to be elucidated, it is clear that Ca(2+) provides a balanced activation of mitochondrial energy metabolism that exceeds the alteration of dehydrogenases alone.
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Affiliation(s)
- Brian Glancy
- Laboratory of Cardiac Energetics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20817, USA
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36
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Wang S, Chen J, Valderrábano M. Nutrient restriction preserves calcium cycling and mitochondrial function in cardiac myocytes during ischemia and reperfusion. Cell Calcium 2012; 51:445-51. [PMID: 22424693 DOI: 10.1016/j.ceca.2012.02.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 02/23/2012] [Accepted: 02/24/2012] [Indexed: 11/30/2022]
Abstract
Nutrient restriction (NR) prolongs longevity via enhanced mitochondrial function. We tested the hypothesis that NR enhances resistance to ischemia/reperfusion (IR) arrhythmias via preserved calcium (Ca) cycling and mitochondrial function. We examined the protective effects of NR on regional IR in cultured neonatal rat ventricular myocyte monolayers. Optical mapping of intracellular Ca and mitochondrial membrane potential Δψ(m) was performed using Rhod 2-AM and TMRE, respectively. Regional ischemia was mimicked by covering a portion of monolayer with a glass coverslip until loss of Ca propagation, and reperfusion was mimicked by removing the coverslip. NR was mimicked by culture in serum- and glucose-free medium for 24 h. Relative to controls, NR monolayers: (1) sustained Ca oscillations during longer periods of ischemia (19.2 ± 1.8 min vs 10.4 ± 1.4 min, p<0.001); (2) had attenuated increases in Ca transient duration (CaD) and time decay constant (Tau) during ischemia; (3) had preserved conduction velocity (CV) during early reperfusion, leading to protection against reperfusion arrhythmias; (4) had minimal "rebound" decreased CaD and Tau during reperfusion; and (5) had no depolarization of Δψ(m) during IR. NR attenuates IR arrhythmias via (1) stable calcium cycling and (2) prevention of Δψ(m) depolarization during IR. Enhanced mitochondrial resistance to IR arrhythmias may play a role in NR-induced longevity prolongation.
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Affiliation(s)
- Sufen Wang
- The Methodist Hospital Research Institute, Methodist DeBakey Heart and Vascular Center, Houston, TX, United States
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37
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Johnson JD, Bround MJ, White SA, Luciani DS. Nanospaces between endoplasmic reticulum and mitochondria as control centres of pancreatic β-cell metabolism and survival. PROTOPLASMA 2012; 249 Suppl 1:S49-S58. [PMID: 22105567 DOI: 10.1007/s00709-011-0349-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 11/07/2011] [Indexed: 05/31/2023]
Abstract
Nanometre-scale spaces between organelles represent focused nodes for signal transduction and the control of cellular decisions. The endoplasmic reticulum (ER) and the mitochondria form dynamic quasi-synaptic interaction nanodomains in all cell types examined, but the functional role of these junctions in cellular metabolism and cell survival remains to be fully understood. In this paper, we review recent evidence that ER Ca(2+) channels, such as the RyR and IP(3)R, can signal specifically across this nanodomain to the adjacent mitochondria to pace basal metabolism, with focus on the pancreatic β-cell. Blocking these signals in the basal state leads to a form of programmed cell death associated with reduced ATP and the induction of calpain-10 and hypoxia-inducible factors. On the other hand, the hyperactivity of this signalling domain plays a deleterious role during classical forms of apoptosis. Thus, the nanospace between ER and mitochondria represents a critical rheostat controlling both metabolism and programmed cell death. Many aspects of the mechanisms underlying this control system remain to be uncovered, and new nanotechnologies are required understand these domains at a molecular level.
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Affiliation(s)
- James D Johnson
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada.
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38
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Dedkova EN, Blatter LA. Measuring mitochondrial function in intact cardiac myocytes. J Mol Cell Cardiol 2011; 52:48-61. [PMID: 21964191 DOI: 10.1016/j.yjmcc.2011.08.030] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 07/30/2011] [Accepted: 08/09/2011] [Indexed: 12/01/2022]
Abstract
Mitochondria are involved in cellular functions that go beyond the traditional role of these organelles as the power plants of the cell. Mitochondria have been implicated in several human diseases, including cardiac dysfunction, and play a role in the aging process. Many aspects of our knowledge of mitochondria stem from studies performed on the isolated organelle. Their relative inaccessibility imposes experimental difficulties to study mitochondria in their natural environment-the cytosol of intact cells-and has hampered a comprehensive understanding of the plethora of mitochondrial functions. Here we review currently available methods to study mitochondrial function in intact cardiomyocytes. These methods primarily use different flavors of fluorescent dyes and genetically encoded fluorescent proteins in conjunction with high-resolution imaging techniques. We review methods to study mitochondrial morphology, mitochondrial membrane potential, Ca(2+) and Na(+) signaling, mitochondrial pH regulation, redox state and ROS production, NO signaling, oxygen consumption, ATP generation and the activity of the mitochondrial permeability transition pore. Where appropriate we complement this review on intact myocytes with seminal studies that were performed on isolated mitochondria, permeabilized cells, and in whole hearts.
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Affiliation(s)
- Elena N Dedkova
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL 60612, USA
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Westerblad H, Place N, Yamada T. Mechanisms of skeletal muscle weakness. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 682:279-96. [PMID: 20824532 DOI: 10.1007/978-1-4419-6366-6_16] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
Skeletal muscle weakness is an important feature of numerous -pathological conditions and it may also be a component in normal ageing. Decreased muscular strength can be due to decreased muscle mass and/or intrinsic defects in the muscle cells. In this chapter we will discuss decreased force production due to mechanisms intrinsic to skeletal muscle cells. We will mainly use data from mouse disease models to exemplify defects at various sites in the cellular activation-contraction pathway. We will show that depending on the underlying problem, muscle weakness can be due decreased Ca²(+) release from the sarcoplasmic reticulum, reduced myofibrillar Ca²(+) sensitivity and/or decreased ability of the cross-bridges to generate force.
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Affiliation(s)
- Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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Hertz L, Lovatt D, Goldman SA, Nedergaard M. Adrenoceptors in brain: cellular gene expression and effects on astrocytic metabolism and [Ca(2+)]i. Neurochem Int 2010; 57:411-20. [PMID: 20380860 PMCID: PMC2934885 DOI: 10.1016/j.neuint.2010.03.019] [Citation(s) in RCA: 163] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2009] [Revised: 03/02/2010] [Accepted: 03/31/2010] [Indexed: 11/24/2022]
Abstract
Recent in vivo studies have established astrocytes as a major target for locus coeruleus activation (Bekar et al., 2008), renewing interest in cell culture studies on noradrenergic effects on astrocytes in primary cultures and calling for additional information about the expression of adrenoceptor subtypes on different types of brain cells. In the present communication, mRNA expression of alpha(1)-, alpha(2)- and beta-adrenergic receptors and their subtypes was determined in freshly isolated, cell marker-defined populations of astrocytes, NG2-positive cells, microglia, endothelial cells, and Thy1-positive neurons (mainly glutamatergic projection neurons) in murine cerebral cortex. Immediately after dissection of frontal, parietal and occipital cortex of 10-12-week-old transgenic mice, which combined each cell-type marker with a specific fluorescent signal, the tissue was digested, triturated and centrifuged, yielding a solution of dissociated cells of all types, which were separated by fluorescence-activated cell sorting (FACS). mRNA expression in each cell fraction was determined by microarray analysis. alpha(1A)-Receptors were unequivocally expressed in astrocytes and NG2-positive cells, but absent in other cell types, and alpha(1B)-receptors were not expressed in any cell population. Among alpha(2)-receptors only alpha(2A)-receptors were expressed, unequivocally in astrocytes and NG-positive cells, tentatively in microglia and questionably in Thy1-positive neurons and endothelial cells. beta(1)-Receptors were unequivocally expressed in astrocytes, tentatively in microglia, and questionably in neurons and endothelial cells, whereas beta(2)-adrenergic receptors showed tentative expression in neurons and astrocytes and unequivocal expression in other cell types. This distribution was supported by immunochemical data and its relevance established by previous studies in well-differentiated primary cultures of mouse astrocytes, showing that stimulation of alpha(2)-adrenoceptors increases glycogen formation and oxidative metabolism, the latter by a mechanism depending on intramitochondrial Ca(2+), whereas alpha(1)-adrenoceptor stimulation enhances glutamate uptake, and beta-adrenoceptor activation causes glycogenolysis and increased Na(+), K(+)-ATPase activity. The Ca(2+)- and cAMP-mediated association between energy-consuming and energy-yielding processes is emphasized.
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MESH Headings
- Animals
- Astrocytes/metabolism
- Brain Chemistry/genetics
- Brain Chemistry/physiology
- Calcium Signaling/physiology
- Cell Separation
- Cells, Cultured
- Flow Cytometry
- Gene Expression/physiology
- Glucose/metabolism
- Glycogen/metabolism
- Mice
- Mice, Transgenic/physiology
- Microarray Analysis
- Mitochondria/metabolism
- Oxidation-Reduction
- Pyruvic Acid/metabolism
- RNA/biosynthesis
- RNA/genetics
- Receptors, Adrenergic/biosynthesis
- Receptors, Adrenergic/genetics
- Receptors, Adrenergic, alpha-1/biosynthesis
- Receptors, Adrenergic, alpha-1/genetics
- Receptors, Adrenergic, alpha-2/biosynthesis
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, beta/biosynthesis
- Receptors, Adrenergic, beta/genetics
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Affiliation(s)
- Leif Hertz
- Department of Clinical Pharmacology, College of Basic Medical Sciences, China Medical University, Shenyang, P. R. China
| | - Ditte Lovatt
- Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY 14642
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642
| | - Steven A. Goldman
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642
| | - Maiken Nedergaard
- Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY 14642
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41
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Conn S, Gilliham M. Comparative physiology of elemental distributions in plants. ANNALS OF BOTANY 2010; 105:1081-102. [PMID: 20410048 PMCID: PMC2887064 DOI: 10.1093/aob/mcq027] [Citation(s) in RCA: 184] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Revised: 11/16/2009] [Accepted: 12/16/2009] [Indexed: 05/18/2023]
Abstract
BACKGROUND Plants contain relatively few cell types, each contributing a specialized role in shaping plant function. With respect to plant nutrition, different cell types accumulate certain elements in varying amounts within their storage vacuole. The role and mechanisms underlying cell-specific distribution of elements in plants is poorly understood. SCOPE The phenomenon of cell-specific elemental accumulation has been briefly reviewed previously, but recent technological advances with the potential to probe mechanisms underlying elemental compartmentation have warranted an updated evaluation. We have taken this opportunity to catalogue many of the studies, and techniques used for, recording cell-specific compartmentation of particular elements. More importantly, we use three case-study elements (Ca, Cd and Na) to highlight the basis of such phenomena in terms of their physiological implications and underpinning mechanisms; we also link such distributions to the expression of known ion or solute transporters. CONCLUSIONS Element accumulation patterns are clearly defined by expression of key ion or solute transporters. Although the location of element accumulation is fairly robust, alterations in expression of certain solute transporters, through genetic modifications or by growth under stress, result in perturbations to these patterns. However, redundancy or induced pleiotropic expression effects may complicate attempts to characterize the pathways that lead to cell-specific elemental distribution. Accumulation of one element often has consequences on the accumulation of others, which seems to be driven largely to maintain vacuolar and cytoplasmic osmolarity and charge balance, and also serves as a detoxification mechanism. Altered cell-specific transcriptomics can be shown, in part, to explain some of this compensation.
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Affiliation(s)
- Simon Conn
- School of Agriculture, Food, and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Matthew Gilliham
- School of Agriculture, Food, and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
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42
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Lehnart SE, Maier LS, Hasenfuss G. Abnormalities of calcium metabolism and myocardial contractility depression in the failing heart. Heart Fail Rev 2010; 14:213-24. [PMID: 19434491 PMCID: PMC2772965 DOI: 10.1007/s10741-009-9146-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Heart failure (HF) is characterized by molecular and cellular defects which jointly contribute to decreased cardiac pump function. During the development of the initial cardiac damage which leads to HF, adaptive responses activate physiological countermeasures to overcome depressed cardiac function and to maintain blood supply to vital organs in demand of nutrients. However, during the chronic course of most HF syndromes, these compensatory mechanisms are sustained beyond months and contribute to progressive maladaptive remodeling of the heart which is associated with a worse outcome. Of pathophysiological significance are mechanisms which directly control cardiac contractile function including ion- and receptor-mediated intracellular signaling pathways. Importantly, signaling cascades of stress adaptation such as intracellular calcium (Ca(2+)) and 3'-5'-cyclic adenosine monophosphate (cAMP) become dysregulated in HF directly contributing to adverse cardiac remodeling and depression of systolic and diastolic function. Here, we provide an update about Ca(2+) and cAMP dependent signaling changes in HF, how these changes affect cardiac function, and novel therapeutic strategies which directly address the signaling defects.
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Affiliation(s)
- Stephan E Lehnart
- Department of Cardiology & Pulmonology, Center of Molecular Cardiology, UMG Heart Center, Georg August University Medical School, Goettingen, Germany.
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43
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Bereiter-Hahn J, Jendrach M. Mitochondrial dynamics. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 284:1-65. [PMID: 20875628 DOI: 10.1016/s1937-6448(10)84001-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mitochondrial dynamics is a key feature for the interaction of mitochondria with other organelles within a cell and also for the maintenance of their own integrity. Four types of mitochondrial dynamics are discussed: Movement within a cell and interactions with the cytoskeleton, fusion and fission events which establish coherence within the chondriome, the dynamic behavior of cristae and their components, and finally, formation and disintegration of mitochondria (mitophagy). Due to these essential functions, disturbed mitochondrial dynamics are inevitably connected to a variety of diseases. Localized ATP gradients, local control of calcium-based messaging, production of reactive oxygen species, and involvement of other metabolic chains, that is, lipid and steroid synthesis, underline that physiology not only results from biochemical reactions but, in addition, resides on the appropriate morphology and topography. These events and their molecular basis have been established recently and are the topic of this review.
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Affiliation(s)
- Jürgen Bereiter-Hahn
- Center of Excellence Macromolecular Complexes, Institute for Cell Biology and Neurosciences, Goethe University, Frankfurt am Main, Germany
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44
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Role of mitochondria in beta-cell function and dysfunction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 654:193-216. [PMID: 20217499 DOI: 10.1007/978-90-481-3271-3_9] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Pancreatic beta-cells are poised to sense glucose and other nutrient secretagogues to regulate insulin exocytosis, thereby maintaining glucose homeostasis. This process requires translation of metabolic substrates into intracellular messengers recognized by the exocytotic machinery. Central to this metabolism-secretion coupling, mitochondria integrate and generate metabolic signals, thereby connecting glucose recognition to insulin exocytosis. In response to a glucose rise, nucleotides and metabolites are generated by mitochondria and participate, together with cytosolic calcium, to the stimulation of insulin release. This review describes the mitochondrion-dependent pathways of regulated insulin secretion. Mitochondrial defects, such as mutations and reactive oxygen species production, are discussed in the context of beta-cell failure that may participate to the etiology of diabetes.
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45
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Webb SE, Rogers KL, Karplus E, Miller AL. The use of aequorins to record and visualize Ca(2+) dynamics: from subcellular microdomains to whole organisms. Methods Cell Biol 2010; 99:263-300. [PMID: 21035690 DOI: 10.1016/b978-0-12-374841-6.00010-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In this chapter, we describe the practical aspects of measuring [Ca(2+)] transients that are generated in a particular cytoplasmic domain, or within a specific organelle or its periorganellar environment, using bioluminescent, genetically encoded and targeted Ca(2+) reporters, especially those based on apoaequorin. We also list examples of the organisms, tissues, and cells that have been transfected with apoaequorin or an apoaequorin-BRET complex, as well as of the organelles and subcellular domains that have been specifically targeted with these bioluminescent Ca(2+) reporters. In addition, we summarize the various techniques used to load the apoaequorin cofactor, coelenterazine, and its analogs into cells, tissues, and intact organisms, and we describe recent advances in the detection and imaging technologies that are currently being used to measure and visualize the luminescence generated by the aequorin-Ca(2+) reaction within these various cytoplasmic domains and subcellular compartments.
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Affiliation(s)
- Sarah E Webb
- Biochemistry and Cell Biology Section and State Key Laboratory of Molecular Neuroscience, Division of Life Science, HKUST, Clear Water Bay, Kowloon, Hong Kong, PR China
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46
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Pozzan T, Rudolf R. Measurements of mitochondrial calcium in vivo. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1317-23. [DOI: 10.1016/j.bbabio.2008.11.012] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 11/20/2008] [Accepted: 11/21/2008] [Indexed: 12/21/2022]
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47
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Salama G, Hwang SM. Simultaneous optical mapping of intracellular free calcium and action potentials from Langendorff perfused hearts. ACTA ACUST UNITED AC 2009; Chapter 12:Unit 12.17. [PMID: 19575468 DOI: 10.1002/0471142956.cy1217s49] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The cardiac action potential (AP) controls the rise and fall of intracellular free Ca2+ (Ca(i)), and thus the amplitude and kinetics of force generation. Besides excitation-contraction coupling, the reverse process where Ca(i) influences the AP through Ca(i)-dependent ionic currents has been implicated as the mechanism underlying QT alternans and cardiac arrhythmias in heart failure, ischemia/reperfusion, cardiac myopathy, myocardial infarction, congenital and drug-induced long QT syndrome, and ventricular fibrillation. The development of dual optical mapping at high spatial and temporal resolution provides a powerful tool to investigate the role of Ca(i) anomalies in eliciting cardiac arrhythmias. This unit describes experimental protocols to map APs and Ca(i) transients from perfused hearts by labeling the heart with two fluorescent dyes, one to measure transmembrane potential (Vm), the other Ca(i) transients. High spatial and temporal resolution is achieved by selecting Vm and Ca(i) probes with the same excitation but different emission wavelengths, to avoid cross-talk and mechanical components.
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Affiliation(s)
- Guy Salama
- University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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48
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Mann ZF, Duchen MR, Gale JE. Mitochondria modulate the spatio-temporal properties of intra- and intercellular Ca2+ signals in cochlear supporting cells. Cell Calcium 2009; 46:136-46. [PMID: 19631380 DOI: 10.1016/j.ceca.2009.06.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 06/12/2009] [Accepted: 06/28/2009] [Indexed: 10/20/2022]
Abstract
In the cochlea, cell damage triggers intercellular Ca2+ waves that propagate through the glial-like supporting cells that surround receptor hair cells. These Ca2+ waves are thought to convey information about sensory hair cell-damage to the surrounding supporting cells within the cochlear epithelium. Mitochondria are key regulators of cytoplasmic Ca2+ concentration ([Ca2+](cyt)), and yet little is known about their role during the propagation of such intercellular Ca2+ signalling. Using neonatal rat cochlear explants and fluorescence imaging techniques, we explore how mitochondria modulate supporting cell [Ca2+](cyt) signals that are triggered by ATP or by hair cell damage. ATP application (0.1-50 microM) caused a dose dependent increase in [Ca2+](cyt) which was accompanied by an increase in mitochondrial calcium. Blocking mitochondrial Ca2+ uptake by dissipating the mitochondrial membrane potential using CCCP and oligomycin or using Ru360, an inhibitor of the mitochondrial Ca2+ uniporter, enhanced the peak amplitude and duration of ATP-induced [Ca2+](cyt) transients. In the presence of Ru360, the mean propagation velocity, amplitude and extent of spread of damage-induced intercellular Ca2+ waves was significantly increased. Thus, mitochondria function as spatial Ca2+ buffers during agonist-evoked [Ca2+](cyt) signalling in cochlear supporting cells and play a significant role in regulating the spatio-temporal properties of intercellular Ca2+ waves.
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Affiliation(s)
- Zoë F Mann
- UCL Ear Institute, 332 Gray's Inn Road, London WC1X 8EE, UK; Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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49
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Balaban RS. Domestication of the cardiac mitochondrion for energy conversion. J Mol Cell Cardiol 2009; 46:832-41. [PMID: 19265699 PMCID: PMC3177846 DOI: 10.1016/j.yjmcc.2009.02.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Revised: 02/11/2009] [Accepted: 02/13/2009] [Indexed: 10/21/2022]
Abstract
The control of mitochondria energy conversion by cytosolic processes is reviewed. The nature of the cytosolic and mitochondrial potential energy homeostasis over wide ranges of energy utilization is reviewed and the consequences of this homeostasis in the control network are discussed. An analysis of the major candidate cytosolic signaling molecules ADP, Pi and Ca(2+) are reviewed based on the magnitude and source of the cytosolic concentration changes as well as the potential targets of action within the mitochondrial energy conversion system. Based on this analysis, Ca(2+) is the best candidate as a cytosolic signaling molecule for this process based on its ability to act as both a feedforward and feedback indicator of ATP hydrolysis and numerous targets within the matrix to provide a balanced activation of ATP production. These targets include numerous dehydrogenases and the F1-F0-ATPase. Pi is also a good candidate since it is an early signal of a mismatch between cytosolic ATP production and ATP synthesis in the presence of creatine kinase and has multiple targets within oxidative phosphorylation including NADH generation, electron flux in the cytochrome chain and a substrate for the F1-F0-ATPase. The mechanism of the coordinated activation of oxidative phosphorylation by these signaling molecules is discussed in light of the recent discoveries of extensive protein phosphorylation sites and other post-translational modifications. From this review it is clear that the control network associated with the maintenance of the cytosolic potential energy homeostasis is extremely complex with multiple pathways orchestrated to balance the sinks and sources in this system. New tools are needed to image and monitor metabolites within sub-cellular compartments to resolve many of these issues as well as the functional characterization of the numerous matrix post-translational events being discovered along with the enzymatic processes generating and removing these protein modifications.
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Affiliation(s)
- Robert S Balaban
- Laboratory of Cardiac Energetic, National Heart Lung and Blood Institute, Bethesda, MD 20892, USA.
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50
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Kettlewell S, Cabrero P, Nicklin S, Dow J, Davies S, Smith G. Changes of intra-mitochondrial Ca2+ in adult ventricular cardiomyocytes examined using a novel fluorescent Ca2+ indicator targeted to mitochondria. J Mol Cell Cardiol 2009; 46:891-901. [DOI: 10.1016/j.yjmcc.2009.02.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 02/11/2009] [Accepted: 02/12/2009] [Indexed: 10/21/2022]
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