1
|
Wu F, Du H, Overbey E, Kim J, Makhijani P, Martin N, Lerner CA, Nguyen K, Baechle J, Valentino TR, Fuentealba M, Bartleson JM, Halaweh H, Winer S, Meydan C, Garrett-Bakelman F, Sayed N, Melov S, Muratani M, Gerencser AA, Kasler HG, Beheshti A, Mason CE, Furman D, Winer DA. Single-cell analysis identifies conserved features of immune dysfunction in simulated microgravity and spaceflight. Nat Commun 2024; 15:4795. [PMID: 38862487 PMCID: PMC11166937 DOI: 10.1038/s41467-023-42013-y] [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: 12/06/2022] [Accepted: 09/27/2023] [Indexed: 06/13/2024] Open
Abstract
Microgravity is associated with immunological dysfunction, though the mechanisms are poorly understood. Here, using single-cell analysis of human peripheral blood mononuclear cells (PBMCs) exposed to short term (25 hours) simulated microgravity, we characterize altered genes and pathways at basal and stimulated states with a Toll-like Receptor-7/8 agonist. We validate single-cell analysis by RNA sequencing and super-resolution microscopy, and against data from the Inspiration-4 (I4) mission, JAXA (Cell-Free Epigenome) mission, Twins study, and spleens from mice on the International Space Station. Overall, microgravity alters specific pathways for optimal immunity, including the cytoskeleton, interferon signaling, pyroptosis, temperature-shock, innate inflammation (e.g., Coronavirus pathogenesis pathway and IL-6 signaling), nuclear receptors, and sirtuin signaling. Microgravity directs monocyte inflammatory parameters, and impairs T cell and NK cell functionality. Using machine learning, we identify numerous compounds linking microgravity to immune cell transcription, and demonstrate that the flavonol, quercetin, can reverse most abnormal pathways. These results define immune cell alterations in microgravity, and provide opportunities for countermeasures to maintain normal immunity in space.
Collapse
Grants
- R01 MH117406 NIMH NIH HHS
- T32 AG000266 NIA NIH HHS
- This work was supported in part through funds derived from the Buck Institute for Research on Aging (D.A.W., D.F.), and the Huiying Memorial Foundation (D.A.W.). T.V. and J.B. are funded by a T32 NIH fellowship grant (NIA T32 AG000266). C.E.M. thanks the Scientific Computing Unit (SCU) at WCM, the WorldQuant Foundation, NASA (NNX14AH50G, NNX17AB26G, 80NSSC22K0254, NNH18ZTT001N-FG2, 80NSSC22K0254, NNX16AO69A), the National Institutes of Health (R01MH117406), and LLS (MCL7001-18, LLS 9238-16).
Collapse
Affiliation(s)
- Fei Wu
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - Huixun Du
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, 90089, USA
| | - Eliah Overbey
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10021, USA
| | - JangKeun Kim
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Priya Makhijani
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
- Department of Immunology, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Nicolas Martin
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - Chad A Lerner
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - Khiem Nguyen
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - Jordan Baechle
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | | | | | | | - Heather Halaweh
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - Shawn Winer
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5S 1A8, Canada
- Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, ON, Canada
| | - Cem Meydan
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Francine Garrett-Bakelman
- Department of Medicine, University of Virginia, Charlottesville, VA, USA
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA
| | - Nazish Sayed
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Simon Melov
- Buck Institute for Research on Aging, Novato, CA, 94945, USA
| | - Masafumi Muratani
- Transborder Medical Research Center, University of Tsukuba, Ibaraki, 305-8575, Japan
- Department of Genome Biology, Faculty of Medicine, University of Tsukuba, Ibaraki, 305-8575, Japan
| | | | | | - Afshin Beheshti
- Blue Marble Space Institute of Science, Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, 94043, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Christopher E Mason
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10021, USA.
- The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Cornell Medicine, New York, NY, 10021, USA.
- WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medicine, New York, NY, 10021, USA.
- The Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, 10021, USA.
| | - David Furman
- Buck Institute for Research on Aging, Novato, CA, 94945, USA.
- Stanford 1000 Immunomes Project, Stanford University School of Medicine, Stanford, CA, USA.
- Institute for Research in Translational Medicine, Universidad Austral, CONICET, Pilar, Buenos Aires, Argentina.
| | - Daniel A Winer
- Buck Institute for Research on Aging, Novato, CA, 94945, USA.
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, 90089, USA.
- Department of Immunology, University of Toronto, Toronto, ON, M5S 1A8, Canada.
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5S 1A8, Canada.
- Division of Cellular & Molecular Biology, Toronto General Hospital Research Institute (TGHRI), University Health Network, Toronto, ON, M5G 1L7, Canada.
| |
Collapse
|
2
|
Takahashi N, Akaike N, Nagamatsu T, Uchino H, Kudo Y. Effects of TND1128 (a 5-deazaflavin derivative), with self-redox ability, as a mitochondria activator on the mouse brain slice and its comparison with β-NMN. J Pharmacol Sci 2023; 151:93-109. [PMID: 36707184 DOI: 10.1016/j.jphs.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 11/22/2022] [Accepted: 11/29/2022] [Indexed: 12/23/2022] Open
Abstract
We have no definitive treatment for dementia characterized by prolonged neuronal death due to the enormous accumulation of foreign matter, such as β-amyloid. Since Alzheimer's type dementia develops slowly, we may be able to delay the onset and improve neuronal dysfunction by enhancing the energy metabolism of individual neurons. TND1128, a derivative of 5-deazaflavin, is a chemical known to have an efficient self-redox ability. We expected TND1128 as an activator for mitochondrial energy synthesis. We used brain slices prepared from mice 22 ± 2 h pretreated with TND1128 or β-NMN. We measured Ca2+ concentrations in the cytoplasm ([Ca2+]cyt) and mitochondria ([Ca2+]mit) by using fluorescence Ca2+ indicators, Fura-4F, and X-Rhod-1, respectively, and examined the protective effects of drugs on [Ca2+]cyt and [Ca2+]mit overloading by repeating 80K exposure. TND1128 (0.01, 0.1, and 1 mg/kg s.c.) mitigates the dynamics of both [Ca2+]cyt and [Ca2+]mit in a dose-dependent manner. β-NMN (10, 30, and 100 mg/kg s.c.) also showed significant dose-dependent mitigating effects on [Ca2+]cyt, but the effect on the [Ca2+]mit dynamics was insignificant. We confirmed the mitochondria-activating potential of TND1128 in the present study. We expect TND1128 as a drug that rescues deteriorating neurons with aging or disease.
Collapse
Affiliation(s)
- Nanae Takahashi
- Department of Anesthesiology, Tokyo Medical University Hachioji Medical Center 1163 Tatemachi,Hachioji, Tokyo 193-0998, Japan.
| | - Norio Akaike
- Research Division for Clinical Pharmacology, Medical Corporation, Juryou Group, Kumamoto Kinoh Hospital, 6-8-1 Yamamuro, Kita-ku, Kumamoto 860-8518, Japan.
| | - Tomohisa Nagamatsu
- Laboratory of Curative Creation Study for Geriatric-diseases Prevention, Faculty of Pharmacological Sciences, Sojo University, 4-22-1 Ikeda, Nishi-ku, Kumamoto, 860-0082, Japan.
| | - Hiroyuki Uchino
- Department of Anesthesiology, Tokyo Medical University, 6-7-1 Nishishinjuku, Sinjuku-ku, Tokyo 160-0023, Japan.
| | - Yoshihisa Kudo
- Department of Anesthesiology, Tokyo Medical University Hachioji Medical Center 1163 Tatemachi,Hachioji, Tokyo 193-0998, Japan.
| |
Collapse
|
3
|
Lloyd D, Millet CO, Williams CF, Hayes AJ, Pope SJA, Pope I, Borri P, Langbein W, Olsen LF, Isaacs MD, Lunding A. Functional imaging of a model unicell: Spironucleus vortens as an anaerobic but aerotolerant flagellated protist. Adv Microb Physiol 2020; 76:41-79. [PMID: 32408947 DOI: 10.1016/bs.ampbs.2020.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Advances in optical microscopy are continually narrowing the chasm in our appreciation of biological organization between the molecular and cellular levels, but many practical problems are still limiting. Observation is always limited by the rapid dynamics of ultrastructural modifications of intracellular components, and often by cell motility: imaging of the unicellular protist parasite of ornamental fish, Spironucleus vortens, has proved challenging. Autofluorescence of nicotinamide nucleotides and flavins in the 400-580 nm region of the visible spectrum, is the most useful indicator of cellular redox state and hence vitality. Fluorophores emitting in the red or near-infrared (i.e., phosphors) are less damaging and more penetrative than many routinely employed fluors. Mountants containing free radical scavengers minimize fluorophore photobleaching. Two-photon excitation provides a small focal spot, increased penetration, minimizes photon scattering and enables extended observations. Use of quantum dots clarifies the competition between endosomal uptake and exosomal extrusion. Rapid motility (161 μm/s) of the organism makes high resolution of ultrastructure difficult even at high scan speeds. Use of voltage-sensitive dyes determining transmembrane potentials of plasma membrane and hydrogenosomes (modified mitochondria) is also hindered by intracellular motion and controlled anesthesia perturbs membrane organization. Specificity of luminophore binding is always questionable; e.g. cationic lipophilic species widely used to measure membrane potentials also enter membrane-bounded neutral lipid droplet-filled organelles. This appears to be the case in S. vortens, where Coherent Anti-Stokes Raman Scattering (CARS) micro-spectroscopy unequivocally images the latter and simultaneous provides spectral identification at 2840 cm-1. Secondary Harmonic Generation highlights the highly ordered structure of the flagella.
Collapse
Affiliation(s)
- David Lloyd
- School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom; School of Engineering, Cardiff, Wales, United Kingdom
| | - Coralie O Millet
- School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | | | - Anthony J Hayes
- School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Simon J A Pope
- School of Chemistry, Main Building, Cardiff University, Cardiff, Wales, United Kingdom
| | - Iestyn Pope
- School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Paola Borri
- School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Wolfgang Langbein
- School of Physics and Astronomy, Cardiff University, Cardiff, Wales, United Kingdom
| | - Lars Folke Olsen
- Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
| | - Marc D Isaacs
- School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Anita Lunding
- Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
| |
Collapse
|
4
|
High-Throughput Fluorescence Assays for Ion Channels and GPCRs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:27-72. [DOI: 10.1007/978-3-030-12457-1_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
|
5
|
Svab G, Doczi J, Gerencser AA, Ambrus A, Gallyas F, Sümegi B, Tretter L. The Mitochondrial Targets of Neuroprotective Drug Vinpocetine on Primary Neuron Cultures, Brain Capillary Endothelial Cells, Synaptosomes, and Brain Mitochondria. Neurochem Res 2019; 44:2435-2447. [PMID: 31535355 PMCID: PMC6776483 DOI: 10.1007/s11064-019-02871-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 08/29/2019] [Accepted: 09/05/2019] [Indexed: 12/13/2022]
Abstract
Vinpocetine is considered as neuroprotectant drug and used for treatment of brain ischemia and cognitive deficiencies for decades. A number of enzymes, channels and receptors can bind vinpocetine, however the mechanisms of many effects' are still not clear. The present study investigated the effects of vinpocetine from the mitochondrial bioenergetic aspects. In primary brain capillary endothelial cells the purinergic receptor-stimulated mitochondrial Ca2+ uptake and efflux were studied. Vinpocetine exerted a partial inhibition on the mitochondrial calcium efflux. In rodent brain synaptosomes vinpocetine (30 μM) inhibited respiration in uncoupler stimulated synaptosomes and decreased H2O2 release from the nerve terminals in resting and in complex I inhibited conditions, respectively. In isolated rat brain mitochondria using either complex I or complex II substrates leak respiration was stimulated, but ADP-induced respiration was inhibited by vinpocetine. The stimulation of oxidation was associated with a small extent of membrane depolarization. Mitochondrial H2O2 production was inhibited by vinpocetine under all conditions investigated. The most pronounced effects were detected with the complex II substrate succinate. Vinpocetine also mitigated both Ca2+-induced mitochondrial Ca2+-release and Ca2+-induced mitochondrial swelling. It lowered the rate of mitochondrial ATP synthesis, while increasing ATPase activity. These results indicate more than a single mitochondrial target of this vinca alkaloid. The relevance of the affected mitochondrial mechanisms in the anti ischemic effect of vinpocetine is discussed.
Collapse
Affiliation(s)
- Gergely Svab
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest, 1094, Hungary
| | - Judit Doczi
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest, 1094, Hungary
| | - Akos A Gerencser
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest, 1094, Hungary.,Buck Institute for Research on Aging, Novato, CA, USA
| | - Attila Ambrus
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest, 1094, Hungary
| | - Ferenc Gallyas
- Department of Biochemistry and Medical Chemistry, University of Pecs Medical School, Pecs, Hungary.,Szentagothai Research Centre, University of Pecs, Pecs, Hungary.,Nuclear-Mitochondrial Interactions Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Balazs Sümegi
- Department of Biochemistry and Medical Chemistry, University of Pecs Medical School, Pecs, Hungary.,Szentagothai Research Centre, University of Pecs, Pecs, Hungary.,Nuclear-Mitochondrial Interactions Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - László Tretter
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest, 1094, Hungary.
| |
Collapse
|
6
|
Patron M, Granatiero V, Espino J, Rizzuto R, De Stefani D. MICU3 is a tissue-specific enhancer of mitochondrial calcium uptake. Cell Death Differ 2018; 26:179-195. [PMID: 29725115 DOI: 10.1038/s41418-018-0113-8] [Citation(s) in RCA: 147] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 03/05/2018] [Accepted: 03/19/2018] [Indexed: 01/14/2023] Open
Abstract
The versatility and universality of Ca2+ as intracellular messenger is guaranteed by the compartmentalization of changes in [Ca2+]. In this context, mitochondrial Ca2+ plays a central role, by regulating both specific organelle functions and global cellular events. This versatility is also guaranteed by a cell type-specific Ca2+ signaling toolkit controlling specific cellular functions. Accordingly, mitochondrial Ca2+ uptake is mediated by a multimolecular structure, the MCU complex, which differs among various tissues. Its activity is indeed controlled by different components that cooperate to modulate specific channeling properties. We here investigate the role of MICU3, an EF-hand containing protein expressed at high levels, especially in brain. We show that MICU3 forms a disulfide bond-mediated dimer with MICU1, but not with MICU2, and it acts as enhancer of MCU-dependent mitochondrial Ca2+ uptake. Silencing of MICU3 in primary cortical neurons impairs Ca2+ signals elicited by synaptic activity, thus suggesting a specific role in regulating neuronal function.
Collapse
Affiliation(s)
- Maria Patron
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58B, 35131, Padova, Italy.,Max Planck Institute for Biology and Aging, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine (CMMC), University of Cologne, Cologne, Germany
| | - Veronica Granatiero
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58B, 35131, Padova, Italy.,Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, 401 East 61st Street, New York, NY, 10065, United States
| | - Javier Espino
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58B, 35131, Padova, Italy
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58B, 35131, Padova, Italy.
| | - Diego De Stefani
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58B, 35131, Padova, Italy.
| |
Collapse
|
7
|
Guerra G, Lucariello A, Perna A, Botta L, De Luca A, Moccia F. The Role of Endothelial Ca 2+ Signaling in Neurovascular Coupling: A View from the Lumen. Int J Mol Sci 2018; 19:E938. [PMID: 29561829 PMCID: PMC5979341 DOI: 10.3390/ijms19040938] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 03/16/2018] [Accepted: 03/17/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Neurovascular coupling (NVC) is the mechanism whereby an increase in neuronal activity (NA) leads to local elevation in cerebral blood flow (CBF) to match the metabolic requirements of firing neurons. Following synaptic activity, an increase in neuronal and/or astrocyte Ca2+ concentration leads to the synthesis of multiple vasoactive messengers. Curiously, the role of endothelial Ca2+ signaling in NVC has been rather neglected, although endothelial cells are known to control the vascular tone in a Ca2+-dependent manner throughout peripheral vasculature. METHODS We analyzed the literature in search of the most recent updates on the potential role of endothelial Ca2+ signaling in NVC. RESULTS We found that several neurotransmitters (i.e., glutamate and acetylcholine) and neuromodulators (e.g., ATP) can induce dilation of cerebral vessels by inducing an increase in endothelial Ca2+ concentration. This, in turn, results in nitric oxide or prostaglandin E2 release or activate intermediate and small-conductance Ca2+-activated K⁺ channels, which are responsible for endothelial-dependent hyperpolarization (EDH). In addition, brain endothelial cells express multiple transient receptor potential (TRP) channels (i.e., TRPC3, TRPV3, TRPV4, TRPA1), which induce vasodilation by activating EDH. CONCLUSIONS It is possible to conclude that endothelial Ca2+ signaling is an emerging pathway in the control of NVC.
Collapse
Affiliation(s)
- Germano Guerra
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, via F. De Santis, 86100 Campobasso, Italy.
| | - Angela Lucariello
- Department of Mental Health and Preventive Medicine, Section of Human Anatomy, University of Campania "L. Vanvitelli", 81100 Naples, Italy.
| | - Angelica Perna
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, via F. De Santis, 86100 Campobasso, Italy.
| | - Laura Botta
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, via Forlanini 6, 27100 Pavia, Italy.
| | - Antonio De Luca
- Department of Mental Health and Preventive Medicine, Section of Human Anatomy, University of Campania "L. Vanvitelli", 81100 Naples, Italy.
| | - Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, via Forlanini 6, 27100 Pavia, Italy.
| |
Collapse
|
8
|
Gerencser AA, Mookerjee SA, Jastroch M, Brand MD. Measurement of the Absolute Magnitude and Time Courses of Mitochondrial Membrane Potential in Primary and Clonal Pancreatic Beta-Cells. PLoS One 2016; 11:e0159199. [PMID: 27404273 PMCID: PMC4942067 DOI: 10.1371/journal.pone.0159199] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 06/28/2016] [Indexed: 12/22/2022] Open
Abstract
The aim of this study was to simplify, improve and validate quantitative measurement of the mitochondrial membrane potential (ΔψM) in pancreatic β-cells. This built on our previously introduced calculation of the absolute magnitude of ΔψM in intact cells, using time-lapse imaging of the non-quench mode fluorescence of tetramethylrhodamine methyl ester and a bis-oxonol plasma membrane potential (ΔψP) indicator. ΔψM is a central mediator of glucose-stimulated insulin secretion in pancreatic β-cells. ΔψM is at the crossroads of cellular energy production and demand, therefore precise assay of its magnitude is a valuable tool to study how these processes interplay in insulin secretion. Dispersed islet cell cultures allowed cell type-specific, single-cell observations of cell-to-cell heterogeneity of ΔψM and ΔψP. Glucose addition caused hyperpolarization of ΔψM and depolarization of ΔψP. The hyperpolarization was a monophasic step increase, even in cells where the ΔψP depolarization was biphasic. The biphasic response of ΔψP was associated with a larger hyperpolarization of ΔψM than the monophasic response. Analysis of the relationships between ΔψP and ΔψM revealed that primary dispersed β-cells responded to glucose heterogeneously, driven by variable activation of energy metabolism. Sensitivity analysis of the calibration was consistent with β-cells having substantial cell-to-cell variations in amounts of mitochondria, and this was predicted not to impair the accuracy of determinations of relative changes in ΔψM and ΔψP. Finally, we demonstrate a significant problem with using an alternative ΔψM probe, rhodamine 123. In glucose-stimulated and oligomycin-inhibited β-cells the principles of the rhodamine 123 assay were breached, resulting in misleading conclusions.
Collapse
Affiliation(s)
- Akos A. Gerencser
- Buck Institute for Research on Aging, Novato, California, United States of America
- Image Analyst Software, Novato, California, United States of America
| | - Shona A. Mookerjee
- Buck Institute for Research on Aging, Novato, California, United States of America
- Touro University California College of Pharmacy, Vallejo, California, United States of America
| | - Martin Jastroch
- Buck Institute for Research on Aging, Novato, California, United States of America
| | - Martin D. Brand
- Buck Institute for Research on Aging, Novato, California, United States of America
| |
Collapse
|
9
|
Stary V, Puppala D, Scherrer-Crosbie M, Dillmann WH, Armoundas AA. SERCA2a upregulation ameliorates cellular alternans induced by metabolic inhibition. J Appl Physiol (1985) 2016; 120:865-75. [PMID: 26846549 DOI: 10.1152/japplphysiol.00588.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 01/27/2016] [Indexed: 12/26/2022] Open
Abstract
Cardiac alternans has been associated with the incidence of ventricular tachyarrhythmias and sudden cardiac death. The aim of this study was to investigate the effect of impaired mitochondrial function in the genesis of cellular alternans and to examine whether modulating the sarcoplasmic reticulum (SR) Ca(2+)ameliorates the level of alternans. Cardiomyocytes isolated from control and doxycyline-induced sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a (SERCA2a)-upregulated mice were loaded with two different Ca(2+)indicators to selectively measure mitochondrial and cytosolic Ca(2+)using a custom-made fluorescence photometry system. The degree of alternans was defined as the alternans ratio (AR) [1 - (small Ca(2+)intensity)/(large Ca(2+)intensity)]. Blocking of complex I and II, cytochrome-coxidase, F0F1synthase, α-ketoglutarate dehydrogenase of the electron transport chain, increased alternans in both control and SERCA2a mice (P< 0.01). Changes in AR in SERCA2a-upregulated mice were significantly less pronounced than those observed in control in seven of nine tested conditions (P< 0.04).N-acetyl-l-cysteine (NAC), rescued alternans in myocytes that were previously exposed to an oxidizing agent (P< 0.001). CGP, an antagonist of the mitochondrial Na(+)-Ca(2+)exchanger, had the most severe effect on AR. Exposure to cyclosporin A, a blocker of the mitochondrial permeability transition pore reduced CGP-induced alternans (P< 0.0001). The major findings of this study are that impairment of mitochondrial Ca(2+)cycling and energy production leads to a higher amplitude of alternans in both control and SERCA2a-upregulated mice, but changes in SERCA2a-upregulated mice are less severe, indicating that SERCA2a mice are more capable of sustaining electrical stability during stress. This suggests a relationship between sarcoplasmic Ca(2+)content and mitochondrial dysfunction during alternans, which may potentially help to understand changes in Ca(2+)signaling in myocytes from diseased hearts, leading to new therapeutic targets.
Collapse
Affiliation(s)
- Victoria Stary
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, Massachusetts; Department of Cardiology and Pulmonology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany; and
| | - Dheeraj Puppala
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, Massachusetts
| | | | - Wolfgang H Dillmann
- Department of Medicine, University of California San Diego, La Jolla, California
| | - Antonis A Armoundas
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, Massachusetts;
| |
Collapse
|
10
|
Loss-of-function mutations in MICU1 cause a brain and muscle disorder linked to primary alterations in mitochondrial calcium signaling. Nat Genet 2013; 46:188-93. [PMID: 24336167 DOI: 10.1038/ng.2851] [Citation(s) in RCA: 276] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 11/20/2013] [Indexed: 12/12/2022]
Abstract
Mitochondrial Ca(2+) uptake has key roles in cell life and death. Physiological Ca(2+) signaling regulates aerobic metabolism, whereas pathological Ca(2+) overload triggers cell death. Mitochondrial Ca(2+) uptake is mediated by the Ca(2+) uniporter complex in the inner mitochondrial membrane, which comprises MCU, a Ca(2+)-selective ion channel, and its regulator, MICU1. Here we report mutations of MICU1 in individuals with a disease phenotype characterized by proximal myopathy, learning difficulties and a progressive extrapyramidal movement disorder. In fibroblasts from subjects with MICU1 mutations, agonist-induced mitochondrial Ca(2+) uptake at low cytosolic Ca(2+) concentrations was increased, and cytosolic Ca(2+) signals were reduced. Although resting mitochondrial membrane potential was unchanged in MICU1-deficient cells, the mitochondrial network was severely fragmented. Whereas the pathophysiology of muscular dystrophy and the core myopathies involves abnormal mitochondrial Ca(2+) handling, the phenotype associated with MICU1 deficiency is caused by a primary defect in mitochondrial Ca(2+) signaling, demonstrating the crucial role of mitochondrial Ca(2+) uptake in humans.
Collapse
|
11
|
Carbamazepine suppresses calpain-mediated autophagy impairment after ischemia/reperfusion in mouse livers. Toxicol Appl Pharmacol 2013; 273:600-10. [PMID: 24126417 DOI: 10.1016/j.taap.2013.10.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 09/29/2013] [Accepted: 10/02/2013] [Indexed: 02/07/2023]
Abstract
Onset of the mitochondrial permeability transition (MPT) plays a causative role in ischemia/reperfusion (I/R) injury. Current therapeutic strategies for reducing reperfusion injury remain disappointing. Autophagy is a lysosome-mediated, catabolic process that timely eliminates abnormal or damaged cellular constituents and organelles such as dysfunctional mitochondria. I/R induces calcium overloading and calpain activation, leading to degradation of key autophagy-related proteins (Atg). Carbamazepine (CBZ), an FDA-approved anticonvulsant drug, has recently been reported to increase autophagy. We investigated the effects of CBZ on hepatic I/R injury. Hepatocytes and livers from male C57BL/6 mice were subjected to simulated in vitro, as well as in vivo I/R, respectively. Cell death, intracellular calcium, calpain activity, changes in autophagy-related proteins (Atg), autophagic flux, MPT and mitochondrial membrane potential after I/R were analyzed in the presence and absence of 20 μM CBZ. CBZ significantly increased hepatocyte viability after reperfusion. Confocal microscopy revealed that CBZ prevented calcium overloading, the onset of the MPT and mitochondrial depolarization. Immunoblotting and fluorometric analysis showed that CBZ blocked calpain activation, depletion of Atg7 and Beclin-1 and loss of autophagic flux after reperfusion. Intravital multiphoton imaging of anesthetized mice demonstrated that CBZ substantially reversed autophagic defects and mitochondrial dysfunction after I/R in vivo. In conclusion, CBZ prevents calcium overloading and calpain activation, which, in turn, suppresses Atg7 and Beclin-1 depletion, defective autophagy, onset of the MPT and cell death after I/R.
Collapse
|
12
|
Hyrc KL, Minta A, Escamilla PR, Chan PPL, Meshik XA, Goldberg MP. Synthesis and properties of Asante Calcium Red--a novel family of long excitation wavelength calcium indicators. Cell Calcium 2013; 54:320-33. [PMID: 24017967 DOI: 10.1016/j.ceca.2013.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 07/29/2013] [Accepted: 08/01/2013] [Indexed: 10/26/2022]
Abstract
Although many synthetic calcium indicators are available, a search for compounds with improved characteristics continues. Here, we describe the synthesis and properties of Asante Calcium Red-1 (ACR-1) and its low affinity derivative (ACR-1-LA) created by linking BAPTA to seminaphthofluorescein. The indicators combine a visible light (450-540 nm) excitation with deep-red fluorescence (640 nm). Upon Ca2+ binding, the indicators raise their fluorescence with longer excitation wavelengths producing higher responses. Although the changes occur without any spectral shifts, it is possible to ratio Ca(2+)-dependent (640 nm) and quasi-independent (530 nm) emission when using visible (< 490 nm) or multiphoton (∼780 nm) excitation. Therefore, both probes can be used as single wavelength or, less dynamic, ratiometric indicators. Long indicator emission might allow easy [Ca2+]i measurement in GFP expressing cells. The indicators bind Ca2+ with either high (Kd = 0.49 ± 0.07 μM; ACR-1) or low affinity (Kd = 6.65 ± 0.13 μM; ACR-1-LA). Chelating Zn2+ (Kd = 0.38 ± 0.02 nM) or Mg2+ (Kd∼5mM) slightly raises and binding Co2+ quenches dye fluorescence. New indicators are somewhat pH-sensitive (pKa = 6.31 ± 0.07), but fairly resistant to bleaching. The probes are rather dim, which combined with low AM ester loading efficiency, might complicate in situ imaging. Despite potential drawbacks, ACR-1 and ACR-1-LA are promising new calcium indicators.
Collapse
Affiliation(s)
- Krzysztof L Hyrc
- The Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA; Alafi Neuroimaging Laboratory, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | | | | | | | | | | |
Collapse
|
13
|
Venable PW, Taylor TG, Sciuto KJ, Zhao J, Shibayama J, Warren M, Spitzer KW, Zaitsev AV. Detection of mitochondrial depolarization/recovery during ischaemia--reperfusion using spectral properties of confocally recorded TMRM fluorescence. J Physiol 2013; 591:2781-94. [PMID: 23529126 DOI: 10.1113/jphysiol.2012.248153] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Timing and pattern of mitochondrial potential (m) depolarization during no-flow ischaemia-reperfusion (I-R) remain controversial, at least in part due to difficulties in interpreting the changes in the fluorescence of m-sensitive dyes such as TMRM. The objective of this study was to develop a new approach for interpreting confocal TMRM signals during I-R based on spatial periodicity of mitochondrial packaging in ventricular cardiomyocytes. TMRM fluorescence (FTMRM) was recorded from Langendorff-perfused rabbit hearts immobilized with blebbistatin using either a confocal microscope or an optical mapping system. The hearts were studied under normal conditions, during mitochondrial uncoupling using the protonophore FCCP, and during I-R. Confocal images of FTMRM were subjected to spatial Fourier transform which revealed distinct peaks at a spatial frequency of ∼2 μm(-1). The area under the peak (MPA) progressively decreased upon application of increasing concentrations of FCCP (0.3-20 μm), becoming undetectable at 5-20 μm FCCP. During ischaemia, a dramatic decrease in MPA, reaching the low/undetectable level comparable to that induced by 5-20 μm FCCP, was observed between 27 and 69 min of ischaemia. Upon reperfusion, a heterogeneous MPA recovery was observed, but not a de novo MPA decrease. Both confocal and wide-field imaging registered a consistent decrease in spatially averaged FTMRM in the presence of 5 μm FCCP, but no consistent change in this parameter during I-R. We conclude that MPA derived from confocal images provides a sensitive and specific indicator of significant mitochondrial depolarization or recovery during I-R. In contrast, spatially averaged FTMRM is not a reliable indicator of m changes during I-R.
Collapse
Affiliation(s)
- Paul W Venable
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, 95 S 2000 E, Salt Lake City, UT 84112-5000, USA
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Loss of OPA1 disturbs cellular calcium homeostasis and sensitizes for excitotoxicity. Cell Death Differ 2012; 20:353-65. [PMID: 23138851 DOI: 10.1038/cdd.2012.128] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Optic atrophy 1 (OPA1) mutations cause dominant optic atrophy (DOA) with retinal ganglion cell (RGC) and optic nerve degeneration. The mechanism for the selective degeneration of RGCs in DOA remains elusive. To address the mechanism, we reduced OPA1 protein expression in cell lines and RGCs by RNA interference. OPA1 loss results in mitochondrial fragmentation, deficiency in oxidative phosphorylation, decreased ATP levels, decreased mitochondrial Ca(2+) retention capacity, reduced mtDNA copy numbers, and sensitization to apoptotic insults. We demonstrate profound cristae depletion and loss of crista junctions in OPA1 knockdown cells, whereas the remaining crista junctions preserve their normal size. OPA1-depleted cells exhibit decreased agonist-evoked mitochondrial Ca(2+) transients and corresponding reduction of NAD(+) to NADH, but the impairment in NADH oxidation leads to an overall more reduced mitochondrial NADH pool. Although in our model OPA1 loss in RGCs has no apparent impact on mitochondrial morphology, it decreases buffering of cytosolic Ca(2+) and sensitizes RGCs to excitotoxic injury. Exposure to glutamate triggers delayed calcium deregulation (DCD), often in a reversible manner, indicating partial resistance of RGCs to this injury. However, when OPA1 is depleted, DCD becomes irreversible. Thus, our data show that whereas OPA1 is required for mitochondrial fusion, maintenance of crista morphology and oxidative phosphorylation, loss of OPA1 also results in defective Ca(2+) homeostasis.
Collapse
|
15
|
Piccoli C, Quarato G, D'Aprile A, Montemurno E, Scrima R, Ripoli M, Gomaraschi M, Cirillo P, Boffoli D, Calabresi L, Gesualdo L, Capitanio N. Native LDL-induced oxidative stress in human proximal tubular cells: multiple players involved. J Cell Mol Med 2012; 15:375-95. [PMID: 19863698 PMCID: PMC3822803 DOI: 10.1111/j.1582-4934.2009.00946.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Dyslipidemia is a well-established condition proved to accelerate the progression of chronic kidney disease leading to tubulo-interstitial injury. However, the molecular aspects of the dyslipidemia-induced renal damage have not been fully clarified and in particular the role played by low-density lipoproteins (LDLs). This study aimed to examine the effects of native non-oxidized LDL on cellular oxidative metabolism in cultured human proximal tubular cells. By means of confocal microscopy imaging combined to respirometric and enzymatic assays it is shown that purified native LDL caused a marked increase of cellular reactive oxygen species (ROS) production, which was mediated by activation of NADPH oxidase(s) and by mitochondrial dysfunction by means of a ROS-induced ROS release mechanism. The LDL-dependent mitochondrial alterations comprised inhibition of the respiratory chain activity, enhanced ROS production, uncoupling of the oxidative phosphorylation efficiency, collapse of the mtΔΨ, increased Ca2+ uptake and loss of cytochrome c. All the above LDL-induced effects were completely abrogated by chelating extracellular Ca2+ as well as by inhibition of the Ca2+-activated cytoplas-mic phospholipase A2, NADPH oxidase and mitochondrial permeability transition. We propose a mechanicistic model whereby the LDL-induced intracellular redox unbalance is triggered by a Ca2+ inward flux-dependent commencement of cPLA2 followed by activation of a lipid- and ROS-based cross-talking signalling pathway. This involves first oxidants production via the plasmamembrane NADPH oxidase and then propagates downstream to mitochondria eliciting redox- and Ca2+-dependent dysfunctions leading to cell-harming conditions. These findings may help to clarify the mechanism of dyslipidemia-induced renal damage and suggest new potential targets for specific therapeutic strategies to prevent oxidative stress implicated in kidney diseases.
Collapse
Affiliation(s)
- Claudia Piccoli
- Department of Biomedical Science, University of Foggia, Foggia, Italy
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Gerencser AA, Chinopoulos C, Birket MJ, Jastroch M, Vitelli C, Nicholls DG, Brand MD. Quantitative measurement of mitochondrial membrane potential in cultured cells: calcium-induced de- and hyperpolarization of neuronal mitochondria. J Physiol 2012; 590:2845-71. [PMID: 22495585 DOI: 10.1113/jphysiol.2012.228387] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mitochondrial membrane potential (ΔΨM) is a central intermediate in oxidative energy metabolism. Although ΔΨM is routinely measured qualitatively or semi-quantitatively using fluorescent probes, its quantitative assay in intact cells has been limited mostly to slow, bulk-scale radioisotope distribution methods. Here we derive and verify a biophysical model of fluorescent potentiometric probe compartmentation and dynamics using a bis-oxonol-type indicator of plasma membrane potential (ΔΨP) and the ΔΨM probe tetramethylrhodamine methyl ester (TMRM) using fluorescence imaging and voltage clamp. Using this model we introduce a purely fluorescence-based quantitative assay to measure absolute values of ΔΨM in millivolts as they vary in time in individual cells in monolayer culture. The ΔΨP-dependent distribution of the probes is modelled by Eyring rate theory. Solutions of the model are used to deconvolute ΔΨP and ΔΨM in time from the probe fluorescence intensities, taking into account their slow, ΔΨP-dependent redistribution and Nernstian behaviour. The calibration accounts for matrix:cell volume ratio, high- and low-affinity binding, activity coefficients, background fluorescence and optical dilution, allowing comparisons of potentials in cells or cell types differing in these properties. In cultured rat cortical neurons, ΔΨM is −139 mV at rest, and is regulated between −108 mV and −158 mV by concerted increases in ATP demand and Ca2+-dependent metabolic activation. Sensitivity analysis showed that the standard error of the mean in the absolute calibrated values of resting ΔΨM including all biological and systematic measurement errors introduced by the calibration parameters is less than 11 mV. Between samples treated in different ways, the typical equivalent error is ∼5 mV.
Collapse
Affiliation(s)
- Akos A Gerencser
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA.
| | | | | | | | | | | | | |
Collapse
|
17
|
Vetter I. Development and optimization of FLIPR high throughput calcium assays for ion channels and GPCRs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:45-82. [PMID: 22453938 DOI: 10.1007/978-94-007-2888-2_3] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Ca(2+) permeable ion channels and GPCRs linked to Ca(2+) release are important drug targets, with modulation of Ca(2+) signaling increasingly recognized as a valid therapeutic strategy in a range of diseases. The FLIPR is a high throughput imaging plate reader that has contributed substantially to drug discovery efforts and pharmacological characterization of receptors and ion channels coupled to Ca(2+). Now in its fourth generation, the FLIPR(TETRA) is an industry standard for high throughput Ca(2+) assays. With an increasing number of excitation LED banks and emission filter sets available; FLIPR Ca(2+) assays are becoming more versatile. This chapter describes general methods for establishing robust FLIPR Ca(2+) assays, incorporating practical aspects as well as suggestions for assay optimization, to guide the reader in the development and optimization of high throughput FLIPR assays for ion channels and GPCRs.
Collapse
Affiliation(s)
- Irina Vetter
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia.
| |
Collapse
|
18
|
Abstract
Dopaminergic neurons of the substantia nigra pars compacta are defective in Parkinson's disease, but the specificity of this dysfunction is not understood. One hypothesis is that mitochondrial bioenergetic capacity is intrinsically lower in striatal dopaminergic presynaptic nerve varicosities, making them unusually susceptible to inhibition of electron transport by oxidative damage. To test this hypothesis, we separated isolated synaptosomes bearing dopamine transporters using immunomagnetic beads and compared their respiration with that of the residual nondopaminergic synaptosomes. As predicted, dopaminergic synaptosomes from striatum had lower respiratory rates. However, so did dopaminergic synaptosomes from cortex, indicating a lack of the predicted striatal specificity. We used fluorescent probes to analyze the bioenergetic competence of individual synaptosomes in the two fractions. The respiratory differences became nonsignificant when respiration rates were normalized to the number of respiration-competent synaptosomes, suggesting that differences reflected the quality of the different fractions. To circumvent damage induced by synaptosomal separation, we monitored membrane potentials in whole unseparated single synaptosomes using fluorescent imaging, and then identified the dopaminergic subpopulation using a fluorescent dopamine transporter substrate (ASP(+) [4-(4-diethylaminostyryl)-N-methylpyridinium iodide]). The capacity of dopaminergic and nondopaminergic synaptosomes to maintain plasma membrane and mitochondrial membrane potential under several stresses did not differ. In addition, this capacity did not decline in either subpopulation with age, a risk factor for Parkinson's disease. We conclude that the intrinsic bioenergetic capacities of dopaminergic and nondopaminergic presynaptic synaptosomes from mice do not differ.
Collapse
|
19
|
Oliveira E, Baptista RMF, Costa SPG, Raposo MMM, Lodeiro C. Exploring the Emissive Properties of New Azacrown Compounds Bearing Aryl, Furyl, or Thienyl Moieties: A Special Case of Chelation Enhancement of Fluorescence upon Interaction with Ca2+, Cu2+, or Ni2+. Inorg Chem 2010; 49:10847-57. [DOI: 10.1021/ic101095y] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Elisabete Oliveira
- REQUIMTE, Department of Chemistry, FCT-UNL, 2829-516 Monte de Caparica, Portugal
| | - Rosa M. F. Baptista
- CQ-UM, Center of Chemistry, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal
| | - Susana P. G. Costa
- CQ-UM, Center of Chemistry, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal
| | - M. Manuela M. Raposo
- CQ-UM, Center of Chemistry, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal
| | - Carlos Lodeiro
- REQUIMTE, Department of Chemistry, FCT-UNL, 2829-516 Monte de Caparica, Portugal
- BIOSCOPE Research Team, Faculty of Science, Physical-Chemistry Department, Campus Ourense, University of Vigo, 32004, Ourense, Spain
| |
Collapse
|
20
|
Measurement of instantaneous velocity vectors of organelle transport: mitochondrial transport and bioenergetics in hippocampal neurons. Biophys J 2008; 95:3079-99. [PMID: 18757564 DOI: 10.1529/biophysj.108.135657] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Impaired transport of mitochondria, in dendrites and axons of neurons, and bioenergetic deficit are increasingly recognized to be of pathological importance in neurodegenerative diseases. To study the relationship between transport and bioenergetics, we have developed what to our knowledge is a novel technique to quantify organelle velocity in cultured cells. The aim was to combine measurement of motion and bioenergetic parameters while minimizing photodynamic oxidative artifacts evoked by fluorescence excitation. Velocity determination from sequential fluorescence images is not trivial, and here we describe an application of "optical flow", the flow of gray values in grayscale images, to this problem. Based on the principles of photon shot noise occurring in low light level fluorescence microscopy, we describe and validate here an optical flow-based, robust method to measure velocity vectors for organelles expressing fluorescent proteins. This method features instantaneous velocity determination from a pair of images by detecting motion of edges, with no assumptions about the separation or shapes of the objects in the image. Optical flow was used in combination with single mitochondrion assay of mitochondrial thiol redox status by mitochondrially targeted redox-sensitive green fluorescent protein and measurement of mitochondrial membrane potential by tetramethylrhodamine methyl ester. Mitochondrial populations of resting cultured hippocampal neurons were analyzed. It was found that mitochondria with more oxidized thiol redox status have lower membrane potentials and are smaller in size. These mitochondria are more motile than the average; however, mitochondrial motility is only slightly dependent on the observed bioenergetic parameters and is correlated the best to the size of the mitochondria.
Collapse
|
21
|
Mitochondrial swelling measurement in situ by optimized spatial filtering: astrocyte-neuron differences. Biophys J 2008; 95:2583-98. [PMID: 18424491 DOI: 10.1529/biophysj.107.118620] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Mitochondrial swelling is a hallmark of mitochondrial dysfunction, and is an indicator of the opening of the mitochondrial permeability transition pore. We introduce here a novel quantitative in situ single-cell assay of mitochondrial swelling based on standard wide-field or confocal fluorescence microscopy. This morphometric technique quantifies the relative diameter of mitochondria labeled by targeted fluorescent proteins. Fluorescence micrographs are spatial bandpass filtered transmitting either high or low spatial frequencies. Mitochondrial swelling is measured by the fluorescence intensity ratio of the high- to low-frequency filtered copy of the same image. We have termed this fraction the "thinness ratio". The filters are designed by numeric optimization for sensitivity. We characterized the thinness ratio technique by modeling microscopic image formation and by experimentation in cultured cortical neurons and astrocytes. The frequency domain image processing endows robustness and subresolution sensitivity to the thinness ratio technique, overcoming the limitations of shape measurement approaches. The thinness ratio proved to be highly sensitive to mitochondrial swelling, but insensitive to fission or fusion of mitochondria. We found that in situ astrocytic mitochondria swell upon short-term uncoupling or inhibition of oxidative phosphorylation, whereas such responses are absent in cultured cortical neurons.
Collapse
|
22
|
Abstract
Mitochondria are central for various cellular processes that include ATP production, intracellular Ca(2+) signaling, and generation of reactive oxygen species. Neurons critically depend on mitochondrial function to establish membrane excitability and to execute the complex processes of neurotransmission and plasticity. While much information about mitochondrial properties is available from studies on isolated mitochondria and dissociated cell cultures, less is known about mitochondrial function in intact neurons in brain tissue. However, a detailed description of the interactions between mitochondrial function, energy metabolism, and neuronal activity is crucial for the understanding of the complex physiological behavior of neurons, as well as the pathophysiology of various neurological diseases. The combination of new fluorescence imaging techniques, electrophysiology, and brain slice preparations provides a powerful tool to study mitochondrial function during neuronal activity, with high spatiotemporal resolution. This review summarizes recent findings on mitochondrial Ca(2+) transport, mitochondrial membrane potential (DeltaPsi(m)), and energy metabolism during neuronal activity. We will first discuss interactions of these parameters for experimental stimulation conditions that can be related to the physiological range. We will then describe how mitochondrial and metabolic dysfunction develops during pathological neuronal activity, focusing on temporal lobe epilepsy and its experimental models. The aim is to illustrate that 1) the structure of the mitochondrial compartment is highly dynamic in neurons, 2) there is a fine-tuned coupling between neuronal activity and mitochondrial function, and 3) mitochondria are of central importance for the complex behavior of neurons.
Collapse
Affiliation(s)
- Oliver Kann
- Institut für Neurophysiologie, Charité-Universitätsmedizin Berlin, Tucholskystrasse 2, 10117 Berlin, Germany.
| | | |
Collapse
|
23
|
Foster KA, Galeffi F, Gerich FJ, Turner DA, Müller M. Optical and pharmacological tools to investigate the role of mitochondria during oxidative stress and neurodegeneration. Prog Neurobiol 2006; 79:136-71. [PMID: 16920246 PMCID: PMC1994087 DOI: 10.1016/j.pneurobio.2006.07.001] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Revised: 07/10/2006] [Accepted: 07/11/2006] [Indexed: 02/06/2023]
Abstract
Mitochondria are critical for cellular adenosine triphosphate (ATP) production; however, recent studies suggest that these organelles fulfill a much broader range of tasks. For example, they are involved in the regulation of cytosolic Ca(2+) levels, intracellular pH and apoptosis, and are the major source of reactive oxygen species (ROS). Various reactive molecules that originate from mitochondria, such as ROS, are critical in pathological events, such as ischemia, as well as in physiological events such as long-term potentiation, neuronal-vascular coupling and neuronal-glial interactions. Due to their key roles in the regulation of several cellular functions, the dysfunction of mitochondria may be critical in various brain disorders. There has been increasing interest in the development of tools that modulate mitochondrial function, and the refinement of techniques that allow for real time monitoring of mitochondria, particularly within their intact cellular environment. Innovative imaging techniques are especially powerful since they allow for mitochondrial visualization at high resolution, tracking of mitochondrial structures and optical real time monitoring of parameters of mitochondrial function. The techniques discussed include classic imaging techniques, such as rhodamine-123, the highly advanced semi-conductor nanoparticles (quantum dots), and wide field microscopy as well as high-resolution multiphoton imaging. We have highlighted the use of these techniques to study mitochondrial function in brain tissue and have included studies from our laboratories in which these techniques have been successfully applied.
Collapse
Affiliation(s)
- Kelley A. Foster
- Research and Surgery Services Durham Veterans Affairs Medical Center; Neurosurgery and Neurobiology, Duke University Medical Center, Box 3807, Durham, NC 27710, USA
| | - Francesca Galeffi
- Research and Surgery Services Durham Veterans Affairs Medical Center; Neurosurgery and Neurobiology, Duke University Medical Center, Box 3807, Durham, NC 27710, USA
| | - Florian J. Gerich
- Zentrum für Physiologie und Pathophysiologie, Abteilung Neuro- und Sinnesphysiologie, Georg-August-Universität Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Dennis A. Turner
- Research and Surgery Services Durham Veterans Affairs Medical Center; Neurosurgery and Neurobiology, Duke University Medical Center, Box 3807, Durham, NC 27710, USA
| | - Michael Müller
- DFG Center Molecular Physiology of the Brain, Georg-August-Universität Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
- Zentrum für Physiologie und Pathophysiologie, Abteilung Neuro- und Sinnesphysiologie, Georg-August-Universität Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
| |
Collapse
|
24
|
Yuan H, Gerencser AA, Liot G, Lipton SA, Ellisman M, Perkins GA, Bossy-Wetzel E. Mitochondrial fission is an upstream and required event for bax foci formation in response to nitric oxide in cortical neurons. Cell Death Differ 2006; 14:462-71. [PMID: 17053808 DOI: 10.1038/sj.cdd.4402046] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Mitochondrial dysfunction is an underpinning event in many neurodegenerative disorders. Less clear, however, is how mitochondria become injured during neuronal demise. Nitric oxide (NO) evokes rapid mitochondrial fission in cortical neurons. Interestingly, proapoptotic Bax relocates from the cytoplasm into large foci on mitochondrial scission sites in response to nitrosative stress. Antiapoptotic Bcl-xL does not prevent mitochondrial fission despite its ability to block Bax puncta formation on mitochondria and to mitigate neuronal cell death. Mitofusin 1 (Mfn1) or dominant-negative dynamin-related protein 1(K38A) (Drp1(k38A)) inhibits mitochondrial fission and Bax accumulation on mitochondria induced by exposure to an NO donor. Although NO is known to cause a bioenergetic crisis, lowering ATP by glycolytic or mitochondrial inhibitors neither induces mitochondrial fission nor Bax foci formation on mitochondria. Taken together, these data indicate that the mitochondrial fission machinery acts upstream of the Bcl-2 family of proteins in neurons challenged with nitrosative stress.
Collapse
Affiliation(s)
- H Yuan
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA 92037, USA
| | | | | | | | | | | | | |
Collapse
|
25
|
Barsoum MJ, Yuan H, Gerencser AA, Liot G, Kushnareva Y, Gräber S, Kovacs I, Lee WD, Waggoner J, Cui J, White AD, Bossy B, Martinou JC, Youle RJ, Lipton SA, Ellisman MH, Perkins GA, Bossy-Wetzel E. Nitric oxide-induced mitochondrial fission is regulated by dynamin-related GTPases in neurons. EMBO J 2006; 25:3900-11. [PMID: 16874299 PMCID: PMC1553198 DOI: 10.1038/sj.emboj.7601253] [Citation(s) in RCA: 520] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Accepted: 06/22/2006] [Indexed: 12/19/2022] Open
Abstract
Mitochondria are present as tubular organelles in neuronal projections. Here, we report that mitochondria undergo profound fission in response to nitric oxide (NO) in cortical neurons of primary cultures. Mitochondrial fission by NO occurs long before neurite injury and neuronal cell death. Furthermore, fission is accompanied by ultrastructural damage of mitochondria, autophagy, ATP decline and generation of free radicals. Fission is occasionally asymmetric and can be reversible. Strikingly, mitochondrial fission is also an early event in ischemic stroke in vivo. Mitofusin 1 (Mfn1) or dominant-negative Dynamin related protein 1 (Drp1(K38A)) inhibits mitochondrial fission induced by NO, rotenone and Amyloid-beta peptide. Conversely, overexpression of Drp1 or Fis1 elicits fission and increases neuronal loss. Importantly, NO-induced neuronal cell death was mitigated by Mfn1 and Drp1(K38A). Thus, persistent mitochondrial fission may play a causal role in NO-mediated neurotoxicity.
Collapse
Affiliation(s)
- Mark J Barsoum
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Hua Yuan
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Akos A Gerencser
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
| | - Géraldine Liot
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Yulia Kushnareva
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Simone Gräber
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Imre Kovacs
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Wilson D Lee
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Jenna Waggoner
- National Center for Microscopy and Imaging Research, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Jiankun Cui
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Andrew D White
- National Center for Microscopy and Imaging Research, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Blaise Bossy
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | | | - Richard J Youle
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Stuart A Lipton
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, School of Medicine, University of California, San Diego, La Jolla, CA, USA
- Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Guy A Perkins
- National Center for Microscopy and Imaging Research, School of Medicine, University of California, San Diego, La Jolla, CA, USA
- Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Ella Bossy-Wetzel
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
- Apoptosis & Cell Death Program, The Burnham Institute for Medical Research, 10901 N. Torrey Pines Road, La Jolla, CA 92037, USA. Tel.: +1 858 713 6297; Fax: +1 858 646 3195; E-mail:
| |
Collapse
|
26
|
Kovács R, Kardos J, Heinemann U, Kann O. Mitochondrial calcium ion and membrane potential transients follow the pattern of epileptiform discharges in hippocampal slice cultures. J Neurosci 2005; 25:4260-9. [PMID: 15858052 PMCID: PMC6725115 DOI: 10.1523/jneurosci.4000-04.2005] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Revised: 03/08/2005] [Accepted: 03/14/2005] [Indexed: 11/21/2022] Open
Abstract
Emerging evidence suggests that mitochondrial dysfunction contributes to the pathophysiology of epilepsy. Recurrent mitochondrial Ca2+ ion load during seizures might act on mitochondrial membrane potential (DeltaPsim) and proton motive force. By using electrophysiology and confocal laser-scanning microscopy, we investigated the effects of epileptiform activity, as induced by low-Mg2+ ion perfusion in hippocampal slice cultures, on changes in DeltaPsim and in mitochondrial Ca2+ ion concentration ([Ca2+]m). The mitochondrial compartment was identified by monitoring DeltaPsim in the soma and dendrites of patched CA3 pyramidal cells using the mitochondria-specific voltage-sensitive dye rhodamine-123 (Rh-123). Interictal activity was accompanied by localized mitochondrial depolarization that was restricted to a few mitochondria in small dendrites. In contrast, robust Rh-123 release into the cytosol was observed during seizure-like events (SLEs), indicating simultaneous depolarization of mitochondria. This was critically dependent on Ca2+ ion uptake and extrusion, because inhibition of the mitochondrial Ca2+ ion uniporter by Ru360 and the mitochondrial Na+/Ca2+ ion exchanger by 7-chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one but not the inhibitor of mitochondrial permeability transition pore, cyclosporin A, decreased the SLE-associated mitochondrial depolarization. The Ca2+ ion dependence of simultaneous mitochondrial depolarization suggested enhanced Ca2+ ion cycling across mitochondrial membranes during epileptiform activity. Indeed, [Ca2+]m fluctuated during interictal activity in single dendrites, and these fluctuations spread over the entire mitochondrial compartment during SLEs, as revealed using mitochondria-specific dyes (rhod-2 and rhod-ff) and spatial frequency-based image analysis. These findings strengthen the hypothesis that epileptic activity results in Ca2+ ion-dependent changes in mitochondrial function that might contribute to the neuronal injury during epilepsy.
Collapse
Affiliation(s)
- Richard Kovács
- Department of Neurochemistry, Institute of Biomolecular Chemistry, Chemical Research Center, Hungarian Academy of Sciences, 1525 Budapest, Hungary.
| | | | | | | |
Collapse
|
27
|
Bianchi K, Rimessi A, Prandini A, Szabadkai G, Rizzuto R. Calcium and mitochondria: mechanisms and functions of a troubled relationship. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1742:119-31. [PMID: 15590062 DOI: 10.1016/j.bbamcr.2004.09.015] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Revised: 09/15/2004] [Accepted: 09/16/2004] [Indexed: 01/09/2023]
Abstract
Mitochondria promptly respond to Ca(2+)-mediated cell stimulations with a rapid accumulation of the cation into the matrix. In this article, we review (i) the basic principles of mitochondrial Ca(2+) transport, (ii) the physiological/pathological role of mitochondrial Ca(2+) uptake, (iii) the regulatory mechanisms that may operate in vivo, and (iv) the new targeted Ca(2+) probes that allowed the "rediscovery" of these organelles in calcium signalling.
Collapse
Affiliation(s)
- Katiuscia Bianchi
- Department of Experimental and Diagnostic Medicine and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, 44100 Ferrara, Italy
| | | | | | | | | |
Collapse
|
28
|
Gerencser AA, Adam-Vizi V. Mitochondrial Ca2+ dynamics reveals limited intramitochondrial Ca2+ diffusion. Biophys J 2005; 88:698-714. [PMID: 15501949 PMCID: PMC1305047 DOI: 10.1529/biophysj.104.050062] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Accepted: 10/13/2004] [Indexed: 11/18/2022] Open
Abstract
To reveal heterogeneity of mitochondrial function on the single-mitochondrion level we have studied the spatiotemporal dynamics of the mitochondrial Ca2+ signaling and the mitochondrial membrane potential using wide-field fluorescence imaging and digital image processing techniques. Here we demonstrate first-time discrete sites--intramitochondrial hotspots--of Ca2+ uptake after Ca2+ release from intracellular stores, and spreading of Ca2+ rise within the mitochondria. The phenomenon was characterized by comparison of observations in intact cells stimulated by ATP and in plasma membrane permeabilized or in ionophore-treated cells exposed to elevated buffer [Ca2+]. The findings indicate that Ca2+ diffuses laterally within the mitochondria, and that the diffusion is limited for shorter segments of the mitochondrial network. These observations were supported by mathematical simulation of buffered diffusion. The mitochondrial membrane potential was investigated using the potentiometric dye TMRM. Irradiation-induced fluctuations (flickering) of TMRM fluorescence showed synchronicity over large regions of the mitochondrial network, indicating that certain parts of this network form electrical syncytia. The spatial extension of these syncytia was decreased by 2-aminoethoxydiphenyl borate (2-APB) or by propranolol (blockers of nonclassical mitochondrial permeabilities). Our data suggest that mitochondria form syncytia of electrical conductance whereas the passage of Ca2+ is restricted to the individual organelle.
Collapse
Affiliation(s)
- Akos A Gerencser
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary
| | | |
Collapse
|
29
|
Csanády L, Adam-Vizi V. Ca(2+)- and voltage-dependent gating of Ca(2+)- and ATP-sensitive cationic channels in brain capillary endothelium. Biophys J 2003; 85:313-27. [PMID: 12829486 PMCID: PMC1303087 DOI: 10.1016/s0006-3495(03)74476-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2002] [Accepted: 04/10/2003] [Indexed: 10/21/2022] Open
Abstract
Biophysical properties of the Ca(2+)-activated nonselective cation channel expressed in brain capillaries were studied in inside-out patches from primary cultures of rat brain microvascular endothelial cells. At -40 mV membrane potential, open probability (P(o)) was activated by cytosolic [Ca(2+)] > 1 micro M and was half-maximal at approximately 20 micro M. Increasing [Ca(2+)] stimulated opening rate with little effect on closing rate. At constant [Ca(2+)], P(o) was voltage-dependent, and effective gating charge corresponded to 0.6 +/- 0.1 unitary charges. Depolarization accelerated opening and slowed closing, thereby increasing apparent affinity for Ca(2+). Within approximately 1 min of excision, P(o) declined to a lower steady state with decreased sensitivity toward activating Ca(2+) when studied at a fixed voltage, and toward activating voltage when studied at a fixed [Ca(2+)]. Deactivated channels opened approximately 5-fold slower and closed approximately 10-fold faster. The sulfhydryl-reducing agent dithiotreitol (1 mM) completely reversed acceleration of closing rate but failed to recover opening rate. Single-channel gating was complex; distributions of open and closed dwell times contained at least four and five exponential components, respectively. The longest component of the closed-time distribution was markedly sensitive to both [Ca(2+)] and voltage. We conclude that the biophysical properties of gating of this channel are remarkably similar to those of large-conductance Ca(2+)-activated K(+) channels.
Collapse
Affiliation(s)
- László Csanády
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary.
| | | |
Collapse
|
30
|
Affiliation(s)
- Michael R Duchen
- Life Sciences Imaging Cooperative and Mitochondrial Biology Group, Department of Physiology, University College London, London WC1E 6BT, United Kingdom
| | | | | |
Collapse
|
31
|
Szabadkai G, Simoni AM, Rizzuto R. Mitochondrial Ca2+ uptake requires sustained Ca2+ release from the endoplasmic reticulum. J Biol Chem 2003; 278:15153-61. [PMID: 12586823 DOI: 10.1074/jbc.m300180200] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We analyzed the role of inositol 1,4,5-trisphosphate-induced Ca(2+) release from the endoplasmic reticulum (ER) (i) in powering mitochondrial Ca(2+) uptake and (ii) in maintaining a sustained elevation of cytosolic Ca(2+) concentration ([Ca(2+)](c)). For this purpose, we expressed in HeLa cells aequorin-based Ca(2+)-sensitive probes targeted to different intracellular compartments and studied the effect of two agonists: histamine, acting on endogenous H(1) receptors, and glutamate, acting on co-transfected metabotropic glutamate receptor (mGluR1a), which rapidly inactivates through protein kinase C-dependent phosphorylation and thus causes transient inositol 1,4,5-trisphosphate production. Glutamate induced a transient [Ca(2+)](c) rise and drop in ER luminal [Ca(2+)] ([Ca(2+)](er)), and then the ER refilled with [Ca(2+)](c) at resting values. With histamine, [Ca(2+)](c) after the initial peak stabilized at a sustained plateau, and [Ca(2+)](er) decreased to a low steady-state value. In mitochondria, histamine evoked a much larger mitochondrial Ca(2+) response than glutamate ( approximately 15 versus approximately 65 microm). Protein kinase C inhibition, partly relieving mGluR1a desensitization, reestablished both the [Ca(2+)](c) plateau and the sustained ER Ca(2+) release and markedly increased the mitochondrial Ca(2+) response. Conversely, mitochondrial Ca(2+) uptake evoked by histamine was drastically reduced by very transient ( approximately 2-s) agonist applications. These data indicate that efficient mitochondrial Ca(2+) uptake depends on the preservation of high Ca(2+) microdomains at the mouth of ER Ca(2+) release sites close to mitochondria. This in turn depends on continuous Ca(2+) release balanced by Ca(2+) reuptake into the ER and maintained by Ca(2+) influx from the extracellular space.
Collapse
Affiliation(s)
- György Szabadkai
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, 44100 Ferrara, Italy
| | | | | |
Collapse
|
32
|
Szado T, Kuo KH, Bernard-Helary K, Poburko D, Lee CH, Seow C, Ruegg UT, van Breemen C. Agonist-induced mitochondrial Ca2+ transients in smooth muscle. FASEB J 2003; 17:28-37. [PMID: 12522109 DOI: 10.1096/fj.02-0334com] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We investigated the role of mitochondria (MT) in calcium signaling in a culture of rat aortic smooth muscle cells. We used targeted aequorin to selectively measure [Ca2+] in this organelle. Our results reveal that smooth muscle cell stimulation with agonists causes a large, transient increase in mitochondrial [Ca2+] ([Ca2+]m). This large transient can be blocked with inhibitors of the sarco-endoplasmic reticulum Ca2+-ATPase, suggesting a close relationship between the sarcoplasmic reticulum (SR) and the mitochondria. FCCP completely abolished the response to agonists, and targeted mitochondrial GFP revealed a vast tubular network of MT in these cells. When added before stimulation with ATP, IP3 inhibitors partially blocked the ATP-induced rise in mitochondrial Ca2+ release. The role of the Na+/Ca2+ exchanger (NCX) was examined by removing extracellular Na+. This procedure prevented the decrease in the [Ca2+]m transient normally seen on removal of extracellular Ca2+. We propose a functional linkage of MT and SR dependent on a narrow junctional space between the two organelles in which Ca2+ diffusion is restricted. Approximately half of the mitochondria appear to be associated with the superficial SR, which communicates with the extracellular space via NCX.
Collapse
MESH Headings
- Adenosine Triphosphate/pharmacology
- Aequorin/genetics
- Animals
- Calcium Channel Blockers/pharmacology
- Calcium Channels/physiology
- Calcium Signaling
- Calcium-Transporting ATPases/antagonists & inhibitors
- Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone/pharmacology
- Cell Line
- Cells, Cultured
- Inositol 1,4,5-Trisphosphate Receptors
- Mitochondria/metabolism
- Models, Biological
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/ultrastructure
- Rats
- Receptors, Cytoplasmic and Nuclear/physiology
- Sarcoplasmic Reticulum Calcium-Transporting ATPases
- Sodium-Calcium Exchanger/physiology
- Uncoupling Agents/pharmacology
- Vasopressins/pharmacology
Collapse
Affiliation(s)
- Tania Szado
- The iCAPTUR4E Center, University of British Columbia, St. Paul's Hospital, Vancouver, BC, Canada
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Hara M, Wang X, Kawamura T, Bindokas VP, Dizon RF, Alcoser SY, Magnuson MA, Bell GI. Transgenic mice with green fluorescent protein-labeled pancreatic beta -cells. Am J Physiol Endocrinol Metab 2003; 284:E177-83. [PMID: 12388130 DOI: 10.1152/ajpendo.00321.2002] [Citation(s) in RCA: 252] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have generated transgenic mice that express green fluorescent protein (GFP) under the control of the mouse insulin I gene promoter (MIP). The MIP-GFP mice develop normally and are indistinguishable from control animals with respect to glucose tolerance and pancreatic insulin content. Histological studies showed that the MIP-GFP mice had normal islet architecture with coexpression of insulin and GFP in the beta-cells of all islets. We observed GFP expression in islets from embryonic day E13.5 through adulthood. Studies of beta-cell function revealed no difference in glucose-induced intracellular calcium mobilization between islets from transgenic and control animals. We prepared single-cell suspensions from both isolated islets and whole pancreas from MIP-GFP-transgenic mice and sorted the beta-cells by fluorescence-activated cell sorting based on their green fluorescence. These studies showed that 2.4 +/- 0.2% (n = 6) of the cells in the pancreas of newborn (P1) and 0.9 +/- 0.1% (n = 5) of 8-wk-old mice were beta-cells. The MIP-GFP-transgenic mouse may be a useful tool for studying beta-cell biology in normal and diabetic animals.
Collapse
Affiliation(s)
- Manami Hara
- Department of Medicine, The University of Chicago, Illinois 60637, USA.
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Rapizzi E, Pinton P, Szabadkai G, Wieckowski MR, Vandecasteele G, Baird G, Tuft RA, Fogarty KE, Rizzuto R. Recombinant expression of the voltage-dependent anion channel enhances the transfer of Ca2+ microdomains to mitochondria. J Cell Biol 2002; 159:613-24. [PMID: 12438411 PMCID: PMC2173108 DOI: 10.1083/jcb.200205091] [Citation(s) in RCA: 340] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although the physiological relevance of mitochondrial Ca2+ homeostasis is widely accepted, no information is yet available on the molecular identity of the proteins involved in this process. Here we analyzed the role of the voltage-dependent anion channel (VDAC) of the outer mitochondrial membrane in the transmission of Ca2+ signals between the ER and mitochondria by measuring cytosolic and organelle [Ca2+] with targeted aequorins and Ca2+-sensitive GFPs. In HeLa cells and skeletal myotubes, the transient expression of VDAC enhanced the amplitude of the agonist-dependent increases in mitochondrial matrix Ca2+ concentration by allowing the fast diffusion of Ca2+ from ER release sites to the inner mitochondrial membrane. Indeed, high speed imaging of mitochondrial and cytosolic [Ca2+] changes showed that the delay between the rises occurring in the two compartments is significantly shorter in VDAC-overexpressing cells. As to the functional consequences, VDAC-overexpressing cells are more susceptible to ceramide-induced cell death, thus confirming that mitochondrial Ca2+ uptake plays a key role in the process of apoptosis. These results reveal a novel function for the widely expressed VDAC channel, identifying it as a molecular component of the routes for Ca2+ transport across the mitochondrial membranes.
Collapse
Affiliation(s)
- Elena Rapizzi
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, Telethon Center for Cell Imaging and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Via Borsari 46, I-44100 Ferrara, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Hajnóczky G, Csordás G, Yi M. Old players in a new role: mitochondria-associated membranes, VDAC, and ryanodine receptors as contributors to calcium signal propagation from endoplasmic reticulum to the mitochondria. Cell Calcium 2002; 32:363-77. [PMID: 12543096 DOI: 10.1016/s0143416002001872] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In many cell types, IP(3) and ryanodine receptor (IP(3)R/RyR)-mediated Ca(2+) mobilization from the sarcoendoplasmic reticulum (ER/SR) results in an elevation of mitochondrial matrix [Ca(2+)]. Although delivery of the released Ca(2+) to the mitochondria has been established as a fundamental signaling process, the molecular mechanism underlying mitochondrial Ca(2+) uptake remains a challenge for future studies. The Ca(2+) uptake can be divided into the following three steps: (1) Ca(2+) movement from the IP(3)R/RyR to the outer mitochondrial membrane (OMM); (2) Ca(2+) transport through the OMM; and (3) Ca(2+) transport through the inner mitochondrial membrane (IMM). Evidence has been presented that Ca(2+) delivery to the OMM is facilitated by a local coupling between closely apposed regions of the ER/SR and mitochondria. Recent studies of the dynamic changes in mitochondrial morphology and visualization of the subcellular pattern of the calcium signal provide important clues to the organization of the ER/SR-mitochondrial interface. Interestingly, key steps of phospholipid synthesis and transfer to the mitochondria have also been confined to subdomains of the ER tightly associated with the mitochondria, referred as mitochondria-associated membranes (MAMs). Through the OMM, the voltage-dependent anion channels (VDAC, porin) have been thought to permit free passage of ions and other small molecules. However, recent studies suggest that the VDAC may represent a regulated step in Ca(2+) transport from IP(3)R/RyR to the IMM. A novel proposal regarding the IMM Ca(2+) uptake site is a mitochondrial RyR that would mediate rapid Ca(2+) uptake by mitochondria in excitable cells. An overview of the progress in these directions is described in the present paper.
Collapse
Affiliation(s)
- G Hajnóczky
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, 19107, Philadelphia, PA, USA.
| | | | | |
Collapse
|