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Nevelchuk S, Brawek B, Schwarz N, Valiente-Gabioud A, Wuttke TV, Kovalchuk Y, Koch H, Höllig A, Steiner F, Figarella K, Griesbeck O, Garaschuk O. Morphotype-specific calcium signaling in human microglia. J Neuroinflammation 2024; 21:175. [PMID: 39020359 PMCID: PMC11256502 DOI: 10.1186/s12974-024-03169-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2024] [Accepted: 07/09/2024] [Indexed: 07/19/2024] Open
Abstract
BACKGROUND Key functions of Ca2+ signaling in rodent microglia include monitoring the brain state as well as the surrounding neuronal activity and sensing the danger or damage in their vicinity. Microglial Ca2+ dyshomeostasis is a disease hallmark in many mouse models of neurological disorders but the Ca2+ signal properties of human microglia remain unknown. METHODS We developed a novel genetically-encoded ratiometric Ca2+ indicator, targeting microglial cells in the freshly resected human tissue, organotypically cultured tissue slices and analyzed in situ ongoing Ca2+ signaling of decades-old microglia dwelling in their native microenvironment. RESULTS The data revealed marked compartmentalization of Ca2+ signals, with signal properties differing across the compartments and resident morphotypes. The basal Ca2+ levels were low in ramified and high in ameboid microglia. The fraction of cells with ongoing Ca2+ signaling, the fraction and the amplitude of process Ca2+ signals and the duration of somatic Ca2+ signals decreased when moving from ramified via hypertrophic to ameboid microglia. In contrast, the size of active compartments, the fraction and amplitude of somatic Ca2+ signals and the duration of process Ca2+ signals increased along this pathway.
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Affiliation(s)
- Sofia Nevelchuk
- Department of Neurophysiology, Institute of Physiology, Eberhard Karls University of Tübingen, Keplerstr. 15, 72074, Tübingen, Germany
| | - Bianca Brawek
- Department of Neurophysiology, Institute of Physiology, Eberhard Karls University of Tübingen, Keplerstr. 15, 72074, Tübingen, Germany
| | - Niklas Schwarz
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Ariel Valiente-Gabioud
- Tools for Bio-Imaging, Max-Planck-Institute for Biological Intelligence, Martinsried, Germany
| | - Thomas V Wuttke
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- Department of Neurosurgery, University of Tübingen, Tübingen, Germany
| | - Yury Kovalchuk
- Department of Neurophysiology, Institute of Physiology, Eberhard Karls University of Tübingen, Keplerstr. 15, 72074, Tübingen, Germany
| | - Henner Koch
- Department of Epileptology, Neurology, RWTH Aachen University Hospital, Aachen, Germany
| | - Anke Höllig
- Department of Neurosurgery, RWTH Aachen University, Aachen, Germany
| | - Frederik Steiner
- Department of Neurophysiology, Institute of Physiology, Eberhard Karls University of Tübingen, Keplerstr. 15, 72074, Tübingen, Germany
| | - Katherine Figarella
- Department of Neurophysiology, Institute of Physiology, Eberhard Karls University of Tübingen, Keplerstr. 15, 72074, Tübingen, Germany
- Department of Anesthesiology, Critical Care and Pain Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Oliver Griesbeck
- Tools for Bio-Imaging, Max-Planck-Institute for Biological Intelligence, Martinsried, Germany
| | - Olga Garaschuk
- Department of Neurophysiology, Institute of Physiology, Eberhard Karls University of Tübingen, Keplerstr. 15, 72074, Tübingen, Germany.
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Guillamón-Vivancos T, Vandael D, Torres D, López-Bendito G, Martini FJ. Mesoscale calcium imaging in vivo: evolution and contribution to developmental neuroscience. Front Neurosci 2023; 17:1210199. [PMID: 37592948 PMCID: PMC10427507 DOI: 10.3389/fnins.2023.1210199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/14/2023] [Indexed: 08/19/2023] Open
Abstract
Calcium imaging is commonly used to visualize neural activity in vivo. In particular, mesoscale calcium imaging provides large fields of view, allowing for the simultaneous interrogation of neuron ensembles across the neuraxis. In the field of Developmental Neuroscience, mesoscopic imaging has recently yielded intriguing results that have shed new light on the ontogenesis of neural circuits from the first stages of life. We summarize here the technical approaches, basic notions for data analysis and the main findings provided by this technique in the last few years, with a focus on brain development in mouse models. As new tools develop to optimize calcium imaging in vivo, basic principles of neural development should be revised from a mesoscale perspective, that is, taking into account widespread activation of neuronal ensembles across the brain. In the future, combining mesoscale imaging of the dorsal surface of the brain with imaging of deep structures would ensure a more complete understanding of the construction of circuits. Moreover, the combination of mesoscale calcium imaging with other tools, like electrophysiology or high-resolution microscopy, will make up for the spatial and temporal limitations of this technique.
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Affiliation(s)
- Teresa Guillamón-Vivancos
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d’Alacant, Spain
| | | | | | | | - Francisco J. Martini
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d’Alacant, Spain
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Golbedaghi R, Ildiz GO, Azadbakht R, Fausto R. A new tetramine bis(2-naphthol)-derivative fluorescent chemosensor for aluminum ion (Al3+). J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2021.131775] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Lohr C, Beiersdorfer A, Fischer T, Hirnet D, Rotermund N, Sauer J, Schulz K, Gee CE. Using Genetically Encoded Calcium Indicators to Study Astrocyte Physiology: A Field Guide. Front Cell Neurosci 2021; 15:690147. [PMID: 34177468 PMCID: PMC8226001 DOI: 10.3389/fncel.2021.690147] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 05/06/2021] [Indexed: 01/14/2023] Open
Abstract
Ca2+ imaging is the most frequently used technique to study glial cell physiology. While chemical Ca2+ indicators served to visualize and measure changes in glial cell cytosolic Ca2+ concentration for several decades, genetically encoded Ca2+ indicators (GECIs) have become state of the art in recent years. Great improvements have been made since the development of the first GECI and a large number of GECIs with different physical properties exist, rendering it difficult to select the optimal Ca2+ indicator. This review discusses some of the most frequently used GECIs and their suitability for glial cell research.
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Affiliation(s)
- Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | | | - Timo Fischer
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Daniela Hirnet
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Natalie Rotermund
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Jessica Sauer
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Kristina Schulz
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Christine E Gee
- Institute of Synaptic Physiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Galichet C, Clayton RW, Lovell-Badge R. Novel Tools and Investigative Approaches for the Study of Oligodendrocyte Precursor Cells (NG2-Glia) in CNS Development and Disease. Front Cell Neurosci 2021; 15:673132. [PMID: 33994951 PMCID: PMC8116629 DOI: 10.3389/fncel.2021.673132] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/07/2021] [Indexed: 12/11/2022] Open
Abstract
Oligodendrocyte progenitor cells (OPCs), also referred to as NG2-glia, are the most proliferative cell type in the adult central nervous system. While the primary role of OPCs is to serve as progenitors for oligodendrocytes, in recent years, it has become increasingly clear that OPCs fulfil a number of other functions. Indeed, independent of their role as stem cells, it is evident that OPCs can regulate the metabolic environment, directly interact with and modulate neuronal function, maintain the blood brain barrier (BBB) and regulate inflammation. In this review article, we discuss the state-of-the-art tools and investigative approaches being used to characterize the biology and function of OPCs. From functional genetic investigation to single cell sequencing and from lineage tracing to functional imaging, we discuss the important discoveries uncovered by these techniques, such as functional and spatial OPC heterogeneity, novel OPC marker genes, the interaction of OPCs with other cells types, and how OPCs integrate and respond to signals from neighboring cells. Finally, we review the use of in vitro assay to assess OPC functions. These methodologies promise to lead to ever greater understanding of this enigmatic cell type, which in turn will shed light on the pathogenesis and potential treatment strategies for a number of diseases, such as multiple sclerosis (MS) and gliomas.
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Affiliation(s)
- Christophe Galichet
- Laboratory of Stem Cell Biology and Developmental Genetics, The Francis Crick Institute, London, United Kingdom
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Harding EK, Fung SW, Bonin RP. Insights Into Spinal Dorsal Horn Circuit Function and Dysfunction Using Optical Approaches. Front Neural Circuits 2020; 14:31. [PMID: 32595458 PMCID: PMC7303281 DOI: 10.3389/fncir.2020.00031] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 05/01/2020] [Indexed: 12/13/2022] Open
Abstract
Somatosensation encompasses a variety of essential modalities including touch, pressure, proprioception, temperature, pain, and itch. These peripheral sensations are crucial for all types of behaviors, ranging from social interaction to danger avoidance. Somatosensory information is transmitted from primary afferent fibers in the periphery into the central nervous system via the dorsal horn of the spinal cord. The dorsal horn functions as an intermediary processing center for this information, comprising a complex network of excitatory and inhibitory interneurons as well as projection neurons that transmit the processed somatosensory information from the spinal cord to the brain. It is now known that there can be dysfunction within this spinal cord circuitry in pathological pain conditions and that these perturbations contribute to the development and maintenance of pathological pain. However, the complex and heterogeneous network of the spinal dorsal horn has hampered efforts to further elucidate its role in somatosensory processing. Emerging optical techniques promise to illuminate the underlying organization and function of the dorsal horn and provide insights into the role of spinal cord sensory processing in shaping the behavioral response to somatosensory input that we ultimately observe. This review article will focus on recent advances in optogenetics and fluorescence imaging techniques in the spinal cord, encompassing findings from both in vivo and in vitro preparations. We will also discuss the current limitations and difficulties of employing these techniques to interrogate the spinal cord and current practices and approaches to overcome these challenges.
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Affiliation(s)
- Erika K Harding
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Samuel Wanchi Fung
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada
| | - Robert P Bonin
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.,University of Toronto Centre for the Study of Pain, University of Toronto, Toronto, ON, Canada
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Sattigeri RM. Action Potential: A Vortex Phenomena; Driving Membrane Oscillations. Front Comput Neurosci 2020; 14:21. [PMID: 32256331 PMCID: PMC7093712 DOI: 10.3389/fncom.2020.00021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 02/21/2020] [Indexed: 12/13/2022] Open
Abstract
Hodgkin-Huxley (HH) model has been one of the most successful electrical interpretation of nerve membrane which led to revolutions in the field of computational neuroscience. On the contrary, experimental observations indicate that, an Action Potential (AP) is accompanied with certain physiological changes in the nerve membrane such as, production and absorption of heat; variation of axon diameter, pressure and length. Although, in the early 1900's a Pressure Wave Theory was proposed by E. Wilke, but, due to lack of sophisticated experimental techniques it was left uncharted. Until recently, when Heimburg-Jackson, Hady-Machta and Rvachev, independently proposed Soliton Theory (thermodynamic interpretation of nerve membrane), Mechanical Surface Waves theory (electro-mechanical interpretation) and Rvachev Model (mechano-electrical activation of voltage gated sodium ion channels) respectively; encouraging a deviation from the traditional HH interpretation with justification for the physical changes in the nerve membrane observed experimentally. But, these theories lead to a “hit and miss” scenario because, they do explain certain features (increase/decrease in axon diameter) but miss to explain, correlation between the strength of stimuli and spike rate of AP. Bio-physical models of nerve membrane are thus important for enhancing our understanding regarding the governing dynamics of neural activities encompassing the experimental observations. A novel theory is proposed here which, unravels vortex ring formation due to ion currents in the intracellular and extracellular region leading to variation of pressure causing the increment/decrement in axon diameter. These formations manifest as membrane oscillations which are used to establish a correlation between the strength of stimuli and spike rate of AP. The theory proposed in this paper, brings a paradigm shift in our understanding of neural dynamics from a thorough bio-physical and physiological perspective with promising applications.
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Affiliation(s)
- Raghottam M Sattigeri
- Department of Physics, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, India
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Arkhipov AY, Khaziev EF, Skorinkin AI, Bukharaeva EA, Samigullin DV. Enhancement of the Temporal Resolution of Fluorescent Signals Acquired by the Confocal Microscope. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2020; 26:204-210. [PMID: 32115011 DOI: 10.1017/s1431927620000148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Here, we describe a method of acquisition of fast fluorescent signals with the help of the laser scanning confocal microscope (LSCM). Our method permits an increase in the temporal resolution of acquired signals. The method is based on LSCM recordings of fast fluorescent signals with the shortest achievable time sweep, which are performed with the help of a proprietary algorithm. A series of recordings is made in multiple steps; at each step, the fluorescent signal is incremented by a time interval smaller than the time sweep of the frame of LSCM. The size of the increment determines the achievable time resolution. The convolution of the recorded images results in a signal with the temporal resolution determined by the chosen time increment. This method was applied to register the change in fluorescence (calcium transient) of calcium dye preloaded into peripheral nerve endings by electrical stimulation of the motor nerve. Calculated parameters of the calcium transient were identical to the parameters obtained earlier with the help of a high-speed camera and photodiode. We conclude that the method described here can be applied for the registration of fast fluorescent signals by LSCM with a high spatial and temporal resolution.
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Affiliation(s)
- Arsenii Y Arkhipov
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111Kazan, Russia
- Department of Radiophotonics and Microwave Technologies, Kazan National Research Technical University named after A.N. Tupolev, 420111Kazan, Russia
| | - Eduard F Khaziev
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111Kazan, Russia
- Department of Radiophotonics and Microwave Technologies, Kazan National Research Technical University named after A.N. Tupolev, 420111Kazan, Russia
- Open Laboratory of Neuropharmacology, Kazan Federal University, 420111Kazan, Russia
| | - Andrey I Skorinkin
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111Kazan, Russia
| | - Ellya A Bukharaeva
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111Kazan, Russia
| | - Dmitry V Samigullin
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111Kazan, Russia
- Department of Radiophotonics and Microwave Technologies, Kazan National Research Technical University named after A.N. Tupolev, 420111Kazan, Russia
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Li WH. Functional analysis of islet cells in vitro, in situ, and in vivo. Semin Cell Dev Biol 2020; 103:14-19. [PMID: 32081627 DOI: 10.1016/j.semcdb.2020.02.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 02/05/2020] [Indexed: 12/20/2022]
Abstract
The islet of Langerhans contains at least five types of endocrine cells producing distinct hormones. In response to nutrient or neuronal stimulation, islet endocrine cells release biochemicals including peptide hormones to regulate metabolism and to control glucose homeostasis. It is now recognized that malfunction of islet cells, notably insufficient insulin release of β-cells and hypersecretion of glucagon from α-cells, represents a causal event leading to hyperglycemia and frank diabetes, a disease that is increasing at an alarming rate to reach an epidemic level worldwide. Understanding the mechanisms regulating stimulus-secretion coupling and investigating how islet β-cells maintain a robust secretory activity are important topics in islet biology and diabetes research. To facilitate such studies, a number of biological systems and assay platforms have been developed for the functional analysis of islet cells. These technologies have enabled detailed analyses of individual islets at the cellular level, either in vitro, in situ, or in vivo.
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Affiliation(s)
- Wen-Hong Li
- Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX, 75390-9039, United States.
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Mindukshev IV, Sudnitsyna JS, Skverchinskaya EA, Andreyeva AY, Dobrylko IA, Senchenkova EY, Krivchenko AI, Gambaryan SP. Erythrocytes’ Reactions to Osmotic, Ammonium, and Oxidative Stress Are Inhibited under Hypoxia. BIOCHEMISTRY (MOSCOW), SUPPLEMENT SERIES A: MEMBRANE AND CELL BIOLOGY 2020. [DOI: 10.1134/s1990747819040081] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Chen M, Zhang S, Xing Y, Li X, He Y, Wang Y, Oberholzer J, Ai HW. Genetically Encoded, Photostable Indicators to Image Dynamic Zn 2+ Secretion of Pancreatic Islets. Anal Chem 2019; 91:12212-12219. [PMID: 31475537 PMCID: PMC6773511 DOI: 10.1021/acs.analchem.9b01802] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
As an essential element for living organisms, zinc (Zn2+) exerts its biological functions both intracellularly and extracellularly. Previous studies have reported a number of genetically encoded Zn2+ indicators (GEZIs), which have been widely used to monitor Zn2+ in the cytosol and intracellular organelles. However, it is challenging to localize existing GEZIs to the extracellular space to detect secreted Zn2+. Herein, we report two photostable, green fluorescent protein (GFP) based indicators, ZIBG1 and ZIBG2, which respond to Zn2+ selectively and have affinities suited for detecting Zn2+ secretion from intracellular vesicles. In particular, ZIBG2 can be effectively targeted to the extracellular side of plasma membrane. We applied cell surface-localized ZIBG2 to monitor glucose-induced dynamic Zn2+ secretion from mouse insulinoma MIN6 cells and primary mouse and human pancreatic islets. Because Zn2+ is co-released with insulin from β-cells, the fluorescence of cell surface-localized ZIBG2 was shown to be a strong indicator for the functional potency of islets. Our work here has thus expanded the use of GEZIs to image dynamic Zn2+ secretion in live tissue. Because it is convenient to use genetically encoded indicators for expression over extended periods and for in vivo delivery, we envision future applications of ZIBG2 in development of induced β-cells or islets to advance cell replacement therapies for diabetes and in direct imaging of Zn2+ secretion dynamics in vivo.
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Affiliation(s)
- Minghai Chen
- Center for Membrane and Cell Physiology, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
- Department of Molecular Physiology and Biological Physics, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
| | - Shen Zhang
- Center for Membrane and Cell Physiology, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
- Department of Chemistry, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
| | - Yuan Xing
- Department of Surgery, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
| | - Xinyu Li
- Center for Membrane and Cell Physiology, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
- Department of Molecular Physiology and Biological Physics, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
| | - Yi He
- Department of Surgery, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
| | - Yong Wang
- Department of Surgery, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
| | - José Oberholzer
- Department of Surgery, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
- Department of Bioengineering, and , University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
| | - Hui-wang Ai
- Center for Membrane and Cell Physiology, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
- Department of Molecular Physiology and Biological Physics, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
- Department of Chemistry, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
- Department of Bioengineering, and , University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
- UVA Cancer Center, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, Virginia 22908, United States
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Heiny JA, Cannon SC, DiFranco M. A four-electrode method to study dynamics of ion activity and transport in skeletal muscle fibers. J Gen Physiol 2019; 151:1146-1155. [PMID: 31320390 PMCID: PMC6719403 DOI: 10.1085/jgp.201912398] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 06/18/2019] [Indexed: 11/20/2022] Open
Abstract
Ion movements across biological membranes, driven by electrochemical gradients or active transport mechanisms, control essential cell functions. Membrane ion movements can manifest as electrogenic currents or electroneutral fluxes, and either process can alter the extracellular and/or intracellular concentration of the transported ions. Classic electrophysiological methods allow accurate measurement of membrane ion movements when the transport mechanism produces a net ionic current; however, they cannot directly measure electroneutral fluxes and do not detect any accompanying change in intracellular ion concentrations. Here, we developed a method for simultaneously measuring ion movements and the accompanying dynamic changes in intracellular ion concentrations in intact skeletal muscle fibers under voltage or current clamp in real time. The method combines a two-microelectrode voltage clamp with ion-selective and reference microelectrodes (four-electrode system). We validate the electrical stability of the system and the viability of the preparation for periods of ∼1 h. We demonstrate the power of this method with measurements of intracellular Cl-, H+, and Na+ to show (a) voltage-dependent redistribution of Cl- ions; (b) intracellular pH changes induced by changes in extracellular pCO2; and (c) electroneutral and electrogenic Na+ movements controlled by the Na,K-ATPase. The method is useful for studying a range of transport mechanisms in many cell types, particularly when the transmembrane ion movements are electrically silent and/or when the transport activity measurably changes the intracellular activity of a transported ion.
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Affiliation(s)
- Judith A Heiny
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH
| | - Stephen C Cannon
- Department of Physiology, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA
| | - Marino DiFranco
- Department of Physiology, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA
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Hughes MC, Ramos SV, Turnbull PC, Rebalka IA, Cao A, Monaco CM, Varah NE, Edgett BA, Huber JS, Tadi P, Delfinis LJ, Schlattner U, Simpson JA, Hawke TJ, Perry CG. Early myopathy in Duchenne muscular dystrophy is associated with elevated mitochondrial H 2 O 2 emission during impaired oxidative phosphorylation. J Cachexia Sarcopenia Muscle 2019; 10:643-661. [PMID: 30938481 PMCID: PMC6596403 DOI: 10.1002/jcsm.12405] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 12/13/2018] [Accepted: 01/09/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Muscle wasting and weakness in Duchenne muscular dystrophy (DMD) causes severe locomotor limitations and early death due in part to respiratory muscle failure. Given that current clinical practice focuses on treating secondary complications in this genetic disease, there is a clear need to identify additional contributions in the aetiology of this myopathy for knowledge-guided therapy development. Here, we address the unresolved question of whether the complex impairments observed in DMD are linked to elevated mitochondrial H2 O2 emission in conjunction with impaired oxidative phosphorylation. This study performed a systematic evaluation of the nature and degree of mitochondrial-derived H2 O2 emission and mitochondrial oxidative dysfunction in a mouse model of DMD by designing in vitro bioenergetic assessments that attempt to mimic in vivo conditions known to be critical for the regulation of mitochondrial bioenergetics. METHODS Mitochondrial bioenergetics were compared with functional and histopathological indices of myopathy early in DMD (4 weeks) in D2.B10-DMDmdx /2J mice (D2.mdx)-a model that demonstrates severe muscle weakness. Adenosine diphosphate's (ADP's) central effect of attenuating H2 O2 emission while stimulating respiration was compared under two models of mitochondrial-cytoplasmic phosphate exchange (creatine independent and dependent) in muscles that stained positive for membrane damage (diaphragm, quadriceps, and white gastrocnemius). RESULTS Pathway-specific analyses revealed that Complex I-supported maximal H2 O2 emission was elevated concurrent with a reduced ability of ADP to attenuate emission during respiration in all three muscles (mH2 O2 : +17 to +197% in D2.mdx vs. wild type). This was associated with an impaired ability of ADP to stimulate respiration at sub-maximal and maximal kinetics (-17 to -72% in D2.mdx vs. wild type), as well as a loss of creatine-dependent mitochondrial phosphate shuttling in diaphragm and quadriceps. These changes largely occurred independent of mitochondrial density or abundance of respiratory chain complexes, except for quadriceps. This muscle was also the only one exhibiting decreased calcium retention capacity, which indicates increased sensitivity to calcium-induced permeability transition pore opening. Increased H2 O2 emission was accompanied by a compensatory increase in total glutathione, while oxidative stress markers were unchanged. Mitochondrial bioenergetic dysfunctions were associated with induction of mitochondrial-linked caspase 9, necrosis, and markers of atrophy in some muscles as well as reduced hindlimb torque and reduced respiratory muscle function. CONCLUSIONS These results provide evidence that Complex I dysfunction and loss of central respiratory control by ADP and creatine cause elevated oxidant generation during impaired oxidative phosphorylation. These dysfunctions may contribute to early stage disease pathophysiology and support the growing notion that mitochondria are a potential therapeutic target in this disease.
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Affiliation(s)
- Meghan C. Hughes
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
| | - Sofhia V. Ramos
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
| | - Patrick C. Turnbull
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
| | - Irena A. Rebalka
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
| | - Andrew Cao
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
| | - Cynthia M.F. Monaco
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
| | - Nina E. Varah
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
| | - Brittany A. Edgett
- Department of Human Health and Nutritional Sciences and Cardiovascular Research GroupUniversity of GuelphGuelphONCanada
| | - Jason S. Huber
- Department of Human Health and Nutritional Sciences and Cardiovascular Research GroupUniversity of GuelphGuelphONCanada
| | - Peyman Tadi
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
| | - Luca J. Delfinis
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
| | - U. Schlattner
- Laboratory of Fundamental and Applied Bioenergetics (LBFA) and SFR Environmental and Systems Biology (BEeSy)University Grenoble AlpesGrenobleFrance
| | - Jeremy A. Simpson
- Department of Human Health and Nutritional Sciences and Cardiovascular Research GroupUniversity of GuelphGuelphONCanada
| | - Thomas J. Hawke
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
| | - Christopher G.R. Perry
- School of Kinesiology and Health Science, Muscle Health Research Centre, 344 Norman Bethune CollegeYork UniversityTorontoONCanada
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14
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Hughes MC, Ramos SV, Turnbull PC, Edgett BA, Huber JS, Polidovitch N, Schlattner U, Backx PH, Simpson JA, Perry CGR. Impairments in left ventricular mitochondrial bioenergetics precede overt cardiac dysfunction and remodelling in Duchenne muscular dystrophy. J Physiol 2019; 598:1377-1392. [PMID: 30674086 DOI: 10.1113/jp277306] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Accepted: 01/22/2019] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS Ninety-eight per cent of patients with Duchenne muscular dystrophy (DMD) develop cardiomyopathy, with 40% developing heart failure. While increased propensity for mitochondrial induction of cell death has been observed in left ventricle, it remains unknown whether this is linked to impaired mitochondrial respiratory control and elevated H2 O2 emission prior to the onset of cardiomyopathy. Classic mouse models of DMD demonstrate hyper-regeneration in skeletal muscle which may mask mitochondrial abnormalities. Using a model with less regenerative capacity that is more akin to DMD patients, we observed elevated left ventricular mitochondrial H2 O2 and impaired oxidative phosphorylation in the absence of cardiac remodelling or overt cardiac dysfunction at 4 weeks. These impairments were associated with dysfunctions at complex I, governance by ADP and creatine-dependent phosphate shuttling, which results in a less efficient response to energy demands. Mitochondria may be a therapeutic target for the treatment of cardiomyopathy in DMD. ABSTRACT In Duchenne muscular dystrophy (DMD), mitochondrial dysfunction is predicted as a response to numerous cellular stressors, yet the contribution of mitochondria to the onset of cardiomyopathy remains unknown. To resolve this uncertainty, we designed in vitro assessments of mitochondrial bioenergetics to model mitochondrial control parameters that influence cardiac function. Both left ventricular mitochondrial responsiveness to the central bioenergetic controller ADP and the ability of creatine to facilitate mitochondrial-cytoplasmic phosphate shuttling were assessed. These measurements were performed in D2.B10-DMDmdx /2J mice - a model that demonstrates skeletal muscle atrophy and weakness due to limited regenerative capacities and cardiomyopathy more akin to people with DMD than classic models. At 4 weeks of age, there was no evidence of cardiac remodelling or cardiac dysfunction despite impairments in ADP-stimulated respiration and ADP attenuation of H2 O2 emission. These impairments were seen at both submaximal and maximal ADP concentrations despite no reductions in mitochondrial content markers. The ability of creatine to enhance ADP's control of mitochondrial bioenergetics was also impaired, suggesting an impairment in mitochondrial creatine kinase-dependent phosphate shuttling. Susceptibly to permeability transition pore opening and the subsequent activation of cell death pathways remained unchanged. Mitochondrial H2 O2 emission was elevated despite no change in markers of irreversible oxidative damage, suggesting alternative redox signalling mechanisms should be explored. These findings demonstrate that selective mitochondrial dysfunction precedes the onset of overt cardiomyopathy in D2.mdx mice, suggesting that improving mitochondrial bioenergetics by restoring ADP, creatine-dependent phosphate shuttling and complex I should be considered for treating DMD patients.
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Affiliation(s)
- Meghan C Hughes
- School of Kinesiology and Health Science and the Muscle Health Research Centre, York University, Toronto, ON, Canada
| | - Sofhia V Ramos
- School of Kinesiology and Health Science and the Muscle Health Research Centre, York University, Toronto, ON, Canada
| | - Patrick C Turnbull
- School of Kinesiology and Health Science and the Muscle Health Research Centre, York University, Toronto, ON, Canada
| | - Brittany A Edgett
- Department of Human Health and Nutritional Sciences and Cardiovascular Research Group, University of Guelph, Guelph, ON, Canada.,Department of Pharmacology, Dalhousie Medicine New Brunswick, Saint John, New Brunswick, Canada.,IMPART Team Canada Investigator Network, Saint John, New Brunswick, Canada
| | - Jason S Huber
- Department of Human Health and Nutritional Sciences and Cardiovascular Research Group, University of Guelph, Guelph, ON, Canada
| | - Nazari Polidovitch
- Department of Biology and the Muscle Health Research Centre, York University, Toronto, ON, Canada
| | - Uwe Schlattner
- Laboratory of Fundamental and Applied Bioenergetics (LBFA) and SFR Environmental and Systems Biology (BEeSy), University Grenoble Alpes, Grenoble, France
| | - Peter H Backx
- Department of Biology and the Muscle Health Research Centre, York University, Toronto, ON, Canada
| | - Jeremy A Simpson
- Department of Human Health and Nutritional Sciences and Cardiovascular Research Group, University of Guelph, Guelph, ON, Canada.,IMPART Team Canada Investigator Network, Saint John, New Brunswick, Canada
| | - Christopher G R Perry
- School of Kinesiology and Health Science and the Muscle Health Research Centre, York University, Toronto, ON, Canada
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15
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Peshenko IV, Yu Q, Lim S, Cudia D, Dizhoor AM, Ames JB. Retinal degeneration 3 (RD3) protein, a retinal guanylyl cyclase regulator, forms a monomeric and elongated four-helix bundle. J Biol Chem 2019; 294:2318-2328. [PMID: 30559291 PMCID: PMC6378972 DOI: 10.1074/jbc.ra118.006106] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/07/2018] [Indexed: 12/20/2022] Open
Abstract
Retinal degeneration 3 (RD3) protein promotes accumulation of retinal membrane guanylyl cyclase (RetGC) in the photoreceptor outer segment and suppresses RetGC activation by guanylyl cyclase-activating proteins (GCAPs). Mutations truncating RD3 cause severe congenital blindness by preventing the inhibitory binding of RD3 to the cyclase. The high propensity of RD3 to aggregate in solution has prevented structural analysis. Here, we produced a highly soluble variant of human RD3 (residues 18-160) that is monomeric and can still bind and negatively regulate RetGC. The NMR solution structure of RD3 revealed an elongated backbone structure (70 Å long and 30 Å wide) consisting of a four-helix bundle with a long unstructured loop between helices 1 and 2. The structure reveals that RD3 residues previously implicated in the RetGC binding map to a localized and contiguous area on the structure, involving a loop between helices 2 and 3 and adjacent parts of helices 3 and 4. The NMR structure of RD3 was validated by mutagenesis. Introducing Trp85 or Phe29 to replace Cys or Leu, respectively, disrupts packing in the hydrophobic core and lowers RD3's apparent affinity for RetGC1. Introducing a positive charge at the interface (Glu32 to Lys) also lowered the affinity. Conversely, introducing Val in place of Cys93 stabilized the hydrophobic core and increased the RD3 affinity for the cyclase. The NMR structure of RD3 presented here provides a structural basis for elucidating RD3-RetGC interactions relevant for normal vision or blindness.
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Affiliation(s)
- Igor V Peshenko
- From the Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027 and
| | - Qinhong Yu
- the Department of Chemistry, University of California, Davis, California 95616
| | - Sunghyuk Lim
- the Department of Chemistry, University of California, Davis, California 95616
| | - Diana Cudia
- the Department of Chemistry, University of California, Davis, California 95616
| | - Alexander M Dizhoor
- From the Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027 and
| | - James B Ames
- the Department of Chemistry, University of California, Davis, California 95616
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16
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Reorganization of Septins Modulates Synaptic Transmission at Neuromuscular Junctions. Neuroscience 2019; 404:91-101. [PMID: 30738855 DOI: 10.1016/j.neuroscience.2019.01.060] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 01/27/2019] [Accepted: 01/29/2019] [Indexed: 12/24/2022]
Abstract
Septins (Sept) are highly conserved Guanosine-5'-triphosphate (GTP)-binding cytoskeletal proteins involved in neuronal signaling in the central nervous system but their involvement in signal transmission in peripheral synapses remains unclear. Sept5 and Sept9 proteins were detected in mouse peripheral neuromuscular junctions by immunofluorescence with a greater degree of co-localization with presynaptic than postsynaptic membranes. Preincubation of neuromuscular junction preparations with the inhibitor of Sept dynamics, forchlorfenuron (FCF), decreased co-localization of Sept with presynaptic membranes. FCF introduced ex vivo or in vivo had no effect on the amplitude of the spontaneous endplate currents (EPCs), indicating the absence of postsynaptic effects of FCF. However, FCF decreased acetylcholine (ACh) quantal release in response to nerve stimulation, reduced the amplitude of evoked quantal currents and decreased the number of quanta with long synaptic delays, demonstrating the presynaptic action of FCF. Nevertheless, FCF had no effect on the amplitude of calcium transient in nerve terminals, as detected by calcium-sensitive dye, and slightly decreased the ratio of the second response amplitude to the first one in paired-pulse experiments. These results suggest that FCF-induced decrease in ACh quantal secretion is not due to a decrease in Ca2+ influx but is likely related to the impairment of later stages occurring after Ca2+ entry, such as trafficking, docking or membrane fusion of synaptic vesicles. Therefore, Sept9 and Sept5 are abundantly expressed in presynaptic membranes, and disruption of Sept dynamics suppresses the evoked synchronous and delayed asynchronous quantal release of ACh, strongly suggesting an important role of Sept in the regulation of neurotransmission in peripheral synapses.
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17
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Samigullin DV, Zhilyakov NV, Khaziev EF, Bukharaeva EA, Nikolsky EE. Calcium Transient and Quantal Release in Mouse Neuromuscular Junction Under Extracellular Calcium Concentration Change. BIONANOSCIENCE 2018. [DOI: 10.1007/s12668-018-0558-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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18
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Stein CS, Jadiya P, Zhang X, McLendon JM, Abouassaly GM, Witmer NH, Anderson EJ, Elrod JW, Boudreau RL. Mitoregulin: A lncRNA-Encoded Microprotein that Supports Mitochondrial Supercomplexes and Respiratory Efficiency. Cell Rep 2018; 23:3710-3720.e8. [PMID: 29949756 PMCID: PMC6091870 DOI: 10.1016/j.celrep.2018.06.002] [Citation(s) in RCA: 155] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/16/2018] [Accepted: 05/30/2018] [Indexed: 01/07/2023] Open
Abstract
Mitochondria are composed of many small proteins that control protein synthesis, complex assembly, metabolism, and ion and reactive oxygen species (ROS) handling. We show that a skeletal muscle- and heart-enriched long non-coding RNA, LINC00116, encodes a highly conserved 56-amino-acid microprotein that we named mitoregulin (Mtln). Mtln localizes to the inner mitochondrial membrane, where it binds cardiolipin and influences protein complex assembly. In cultured cells, Mtln overexpression increases mitochondrial membrane potential, respiration rates, and Ca2+ retention capacity while decreasing mitochondrial ROS and matrix-free Ca2+. Mtln-knockout mice display perturbations in mitochondrial respiratory (super)complex formation and activity, fatty acid oxidation, tricarboxylic acid (TCA) cycle enzymes, and Ca2+ retention capacity. Blue-native gel electrophoresis revealed that Mtln co-migrates alongside several complexes, including the complex I assembly module, complex V, and supercomplexes. Under denaturing conditions, Mtln remains in high-molecular-weight complexes, supporting its role as a sticky molecular tether that enhances respiratory efficiency by bolstering protein complex assembly and/or stability.
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Affiliation(s)
- Colleen S Stein
- Department of Internal Medicine, Fraternal Order of Eagles Diabetes Research Center, Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Pooja Jadiya
- Center of Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Xiaoming Zhang
- Department of Internal Medicine, Fraternal Order of Eagles Diabetes Research Center, Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Jared M McLendon
- Department of Internal Medicine, Fraternal Order of Eagles Diabetes Research Center, Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Gabrielle M Abouassaly
- Department of Internal Medicine, Fraternal Order of Eagles Diabetes Research Center, Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Nathan H Witmer
- Department of Internal Medicine, Fraternal Order of Eagles Diabetes Research Center, Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Ethan J Anderson
- Department of Pharmaceutical Sciences and Experimental Therapeutics, Fraternal Order of Eagles Diabetes Research Center, Abboud Cardiovascular Research Center, College of Pharmacy, University of Iowa, Iowa City, IA, USA
| | - John W Elrod
- Center of Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Ryan L Boudreau
- Department of Internal Medicine, Fraternal Order of Eagles Diabetes Research Center, Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
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19
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A method for estimating intracellular ion concentration using optical nanosensors and ratiometric imaging. Sci Rep 2017; 7:10819. [PMID: 28883429 PMCID: PMC5589868 DOI: 10.1038/s41598-017-11162-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 08/18/2017] [Indexed: 11/22/2022] Open
Abstract
Optical nanoparticle (NP)-based sensors have been widely implemented as tools for detection of targeted ions and biomolecules. The NP sensing platform offer a modular design that can incorporate different sensing components for greater target specificity and the ability to tune the dynamic range, as well as encapsulation of multiple dyes to generate a ratiometric signal with varying spectra. Despite these advantages, demonstrating quantitative ion imaging for intracellular measurement still possess a major challenge. Here, we describe fundamentals that enable intracellular validation of this approach using ion-selective nanosensors for investigating calcium (Ca2+) as a model ion. While conventional indicators can improve individual aspects of indicator performance such as Kd, wavelength, and ratiometric measurements, the use of NP sensors can achieve combined benefits of addressing these issues simultaneously. The nanosensor incorporates highly calcium-selective ionophores and two fluorescence indicators that act as signal transducers to facilitate quantitative ratiometric imaging. For intracellular Ca2+ application, the sensors are fine-tuned to physiological sensing range, and live-cell imaging and quantification are demonstrated in HeLa cells loaded with nanosensors and their responsiveness to carbachol-evoked store release (~400 nM). The current nanosensor design thus provides a promising sensing platform for real-time detection and optical determination of intracellular ions.
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20
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Samigullin DV, Khaziev EF, Zhilyakov NV, Bukharaeva EA, Nikolsky EE. Loading a Calcium Dye into Frog Nerve Endings Through the Nerve Stump: Calcium Transient Registration in the Frog Neuromuscular Junction. J Vis Exp 2017. [PMID: 28715368 PMCID: PMC5609652 DOI: 10.3791/55122] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
One of the most feasible methods of measuring presynaptic calcium levels in presynaptic nerve terminals is optical recording. It is based on using calcium-sensitive fluorescent dyes that change their emission intensity or wavelength depending on the concentration of free calcium in the cell. There are several methods used to stain cells with calcium dyes. Most common are the processes of loading the dyes through a micropipette or pre-incubating with the acetoxymethyl ester forms of the dyes. However, these methods are not quite applicable to neuromuscular junctions (NMJs) due to methodological issues that arise. In this article, we present a method for loading a calcium-sensitive dye through the frog nerve stump of the frog nerve into the nerve endings. Since entry of external calcium into nerve terminals and the subsequent binding to the calcium dye occur within the millisecond time-scale, it is necessary to use a fast imaging system to record these interactions. Here, we describe a protocol for recording the calcium transient with a fast CCD camera.
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Affiliation(s)
- Dmitry V Samigullin
- Laboratory of Biophysics of Synaptic Processes, Kazan Scientific Centre, Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences; Open Laboratory of Neuropharmacology, Kazan Federal University; Department of Radiophotonics and Microwave Technologies, A.N. Tupolev Kazan National Research Technical University;
| | - Eduard F Khaziev
- Laboratory of Biophysics of Synaptic Processes, Kazan Scientific Centre, Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences; Open Laboratory of Neuropharmacology, Kazan Federal University; Department of Radiophotonics and Microwave Technologies, A.N. Tupolev Kazan National Research Technical University
| | - Nikita V Zhilyakov
- Laboratory of Biophysics of Synaptic Processes, Kazan Scientific Centre, Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences; Open Laboratory of Neuropharmacology, Kazan Federal University
| | - Ellya A Bukharaeva
- Laboratory of Biophysics of Synaptic Processes, Kazan Scientific Centre, Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences; Open Laboratory of Neuropharmacology, Kazan Federal University
| | - Eugeny E Nikolsky
- Laboratory of Biophysics of Synaptic Processes, Kazan Scientific Centre, Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences; Open Laboratory of Neuropharmacology, Kazan Federal University; Department of Medical and Biological Physics, Kazan State Medical University
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21
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Abstract
Calcium signals control a plethora of essential cellular functions ranging from secretion and contraction to gene expression and sensory signaling cascades. An essential part of intracellular calcium signals originates from the transmembrane flux of calcium ions, which is mainly mediated through different calcium-permeable cation channels with variable calcium selectivity. Opening of individual calcium permeable channels induces a local cytosolic calcium rise that can be highly restricted in time and space. Here, we provide a short overview of the current knowledge about calcium permeation and localized calcium signals in transient receptor potential (TRP) channels. We also present a brief survey of some fundamental theoretical aspects of the local calcium signals generated upon opening of single calcium-permeable channels, and compare theoretical predictions with published experimental data on TRP channel-mediated local calcium signals.
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22
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Foote JR, Levine AP, Behe P, Duchen MR, Segal AW. Imaging the Neutrophil Phagosome and Cytoplasm Using a Ratiometric pH Indicator. J Vis Exp 2017. [PMID: 28448042 PMCID: PMC5564471 DOI: 10.3791/55107] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Neutrophils are crucial to host innate defense and, consequently, constitute an important area of medical research. The phagosome, the intracellular compartment where the killing and digestion of engulfed particles take place, is the main arena for neutrophil pathogen killing that requires tight regulation. Phagosomal pH is one aspect that is carefully controlled, in turn regulating antimicrobial protease activity. Many fluorescent pH-sensitive dyes have been used to visualize the phagosomal environment. S-1 has several advantages over other pH-sensitive dyes, including its dual emission spectra, its resistance to photo-bleaching, and its high pKa. Using this method, we have demonstrated that the neutrophil phagosome is unusually alkaline in comparison to other phagocytes. By using different biochemical conjugations of the dye, the phagosome can be delineated from the cytoplasm so that changes in the size and shape of the phagosome can be assessed. This allows for further monitoring of ionic movement.
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Affiliation(s)
- Juliet R Foote
- Centre for Molecular Medicine, Division of Medicine, University College London
| | - Adam P Levine
- Centre for Molecular Medicine, Division of Medicine, University College London
| | - Philippe Behe
- Centre for Molecular Medicine, Division of Medicine, University College London
| | | | - Anthony W Segal
- Centre for Molecular Medicine, Division of Medicine, University College London;
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23
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Petrov AM, Kravtsova VV, Matchkov VV, Vasiliev AN, Zefirov AL, Chibalin AV, Heiny JA, Krivoi II. Membrane lipid rafts are disturbed in the response of rat skeletal muscle to short-term disuse. Am J Physiol Cell Physiol 2017; 312:C627-C637. [PMID: 28274922 DOI: 10.1152/ajpcell.00365.2016] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 02/22/2017] [Accepted: 03/05/2017] [Indexed: 12/19/2022]
Abstract
Marked loss of skeletal muscle mass occurs under various conditions of disuse, but the molecular and cellular mechanisms leading to atrophy are not completely understood. We investigate early molecular events that might play a role in skeletal muscle remodeling during mechanical unloading (disuse). The effects of acute (6-12 h) hindlimb suspension on the soleus muscles from adult rats were examined. The integrity of plasma membrane lipid rafts was tested utilizing cholera toxin B subunit or fluorescent sterols. In addition, resting intracellular Ca2+ level was analyzed. Acute disuse disturbed the plasma membrane lipid-ordered phase throughout the sarcolemma and was more pronounced in junctional membrane regions. Ouabain (1 µM), which specifically inhibits the Na-K-ATPase α2 isozyme in rodent skeletal muscles, produced similar lipid raft changes in control muscles but was ineffective in suspended muscles, which showed an initial loss of α2 Na-K-ATPase activity. Lipid rafts were able to recover with cholesterol supplementation, suggesting that disturbance results from cholesterol loss. Repetitive nerve stimulation also restores lipid rafts, specifically in the junctional sarcolemma region. Disuse locally lowered the resting intracellular Ca2+ concentration only near the neuromuscular junction of muscle fibers. Our results provide evidence to suggest that the ordering of lipid rafts strongly depends on motor nerve input and may involve interactions with the α2 Na-K-ATPase. Lipid raft disturbance, accompanied by intracellular Ca2+ dysregulation, is among the earliest remodeling events induced by skeletal muscle disuse.
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Affiliation(s)
- Alexey M Petrov
- Department of Normal Physiology, Kazan State Medical University, Kazan, Russia
| | - Violetta V Kravtsova
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia
| | | | - Alexander N Vasiliev
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia
| | - Andrey L Zefirov
- Department of Normal Physiology, Kazan State Medical University, Kazan, Russia
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden; and
| | - Judith A Heiny
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Igor I Krivoi
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia;
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24
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Abstract
Dual wavelength ratiometric imaging has become a powerful tool for the study of pH in intracellular compartments. It allows for the dynamic imaging of live cells while accounting for changes in the focal plane, differential loading of the fluorescent probe, and photobleaching caused by repeated image acquisitions. Ratiometric microscopic imaging has the added advantage over whole population methods of being able to resolve individual cells and even individual organelles. In this chapter we provide a detailed discussion of the basic principles of ratiometric imaging and its application to the measurement of phagosomal pH, including probe selection, the necessary instrumentation, and calibration methods.
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Affiliation(s)
- Johnathan Canton
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON, Canada, M5G 0A4
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON, Canada, M5G 0A4. .,Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, 290 Victoria Street, Toronto, ON, Canada, M5C 1N8.
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25
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Khaziev E, Samigullin D, Zhilyakov N, Fatikhov N, Bukharaeva E, Verkhratsky A, Nikolsky E. Acetylcholine-Induced Inhibition of Presynaptic Calcium Signals and Transmitter Release in the Frog Neuromuscular Junction. Front Physiol 2016; 7:621. [PMID: 28018246 PMCID: PMC5149534 DOI: 10.3389/fphys.2016.00621] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 11/28/2016] [Indexed: 11/29/2022] Open
Abstract
Acetylcholine (ACh), released from axonal terminals of motor neurons in neuromuscular junctions regulates the efficacy of neurotransmission through activation of presynaptic nicotinic and muscarinic autoreceptors. Receptor-mediated presynaptic regulation could reflect either direct action on exocytotic machinery or modulation of Ca2+ entry and resulting intra-terminal Ca2+ dynamics. We have measured free intra-terminal cytosolic Ca2+ ([Ca2+]i) using Oregon-Green 488 microfluorimetry, in parallel with voltage-clamp recordings of spontaneous (mEPC) and evoked (EPC) postsynaptic currents in post-junctional skeletal muscle fiber. Activation of presynaptic muscarinic and nicotinic receptors with exogenous acetylcholine and its non-hydrolized analog carbachol reduced amplitude of the intra-terminal [Ca2+]i transients and decreased quantal content (calculated by dividing the area under EPC curve by the area under mEPC curve). Pharmacological analysis revealed the role of muscarinic receptors of M2 subtype as well as d-tubocurarine-sensitive nicotinic receptor in presynaptic modulation of [Ca2+]i transients. Modulation of synaptic transmission efficacy by ACh receptors was completely eliminated by pharmacological inhibition of N-type Ca2+ channels. We conclude that ACh receptor-mediated reduction of Ca2+ entry into the nerve terminal through N-type Ca2+ channels represents one of possible mechanism of presynaptic modulation in frog neuromuscular junction.
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Affiliation(s)
- Eduard Khaziev
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of SciencesKazan, Russia; Open Laboratory of Neuropharmacology, Kazan (Volga Region) Federal UniversityKazan, Russia; Institute of Applied Electrodynamics, Photonics and Living Systems, A.N. Tupolev Kazan National Research Technical UniversityKazan, Russia
| | - Dmitry Samigullin
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of SciencesKazan, Russia; Open Laboratory of Neuropharmacology, Kazan (Volga Region) Federal UniversityKazan, Russia; Institute of Applied Electrodynamics, Photonics and Living Systems, A.N. Tupolev Kazan National Research Technical UniversityKazan, Russia
| | - Nikita Zhilyakov
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of SciencesKazan, Russia; Open Laboratory of Neuropharmacology, Kazan (Volga Region) Federal UniversityKazan, Russia
| | - Nijaz Fatikhov
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of Sciences Kazan, Russia
| | - Ellya Bukharaeva
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of SciencesKazan, Russia; Open Laboratory of Neuropharmacology, Kazan (Volga Region) Federal UniversityKazan, Russia
| | | | - Evgeny Nikolsky
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of the Russian Academy of SciencesKazan, Russia; Open Laboratory of Neuropharmacology, Kazan (Volga Region) Federal UniversityKazan, Russia; Department of Biophysics, Kazan State Medical UniversityKazan, Russia
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26
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Wagner AM, Strohecker SA, Costello EK, Rood JA, Kneas KA. Water-Soluble Osmium Complexes Suitable for use in Luminescence-Based, Hydrogel-Supported Sensors. J Fluoresc 2016; 26:2271-2280. [PMID: 27664088 DOI: 10.1007/s10895-016-1923-z] [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: 06/27/2016] [Accepted: 08/26/2016] [Indexed: 10/21/2022]
Abstract
Osmium transition metal complexes are of particular interest in luminescence-based sensing applications because of their longer wavelength absorptions and emissions, relative to similar ruthenium and rhenium complexes, that allow for inexpensive excitation and minimize interferences from autofluorescence when the sensor is used in biological samples. Reported here are the photophysical properties of a series of water-soluble osmium complexes suitable for use in hydrogel-based sensors: [Os(bpy)2(sulf-dpp)]Cl2, [Os(phen)2(sulf-dpp)]Cl2, [Os(dpp)2(sulf-dpp)]Cl2, and [Os(CO)2Cl2(sulf-dpp)], where bpy is 2,2'-bipyridine, phen is 1,10-phenanthroline, dpp is 4,7-diphenyl-1,10-phenanthroline, and sulf-dpp is bathophenanthrolinedisulfonic acid disodium salt. The family of complexes showed minimal oxygen quenching, making them particularly well-suited for sensing applications in which oxygen concentration varies. Luminescence anisotropy was found to depend more significantly on net dipole moment than hydrodynamic radius of the molecule, and, as expected, excited state lifetime and luminescence anisotropy were highly dependent on the local environment of the reporter molecule. Results obtained for hydrogel-based relative humidity sensors containing [Os(CO)2Cl2(sulf-dpp)] and [Os(bpy)2(sulf-dpp)]Cl2 complexes highlight the significant potential for this class of compounds in a hydrogel-supported luminescence-based sensing approach.
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Affiliation(s)
- Amy M Wagner
- Department of Chemistry & Biochemistry, Elizabethtown College, One Alpha Drive, Elizabethtown, PA, 17022, USA
| | - Sarah A Strohecker
- Department of Chemistry & Biochemistry, Elizabethtown College, One Alpha Drive, Elizabethtown, PA, 17022, USA
| | - Elizabeth K Costello
- Department of Chemistry & Biochemistry, Elizabethtown College, One Alpha Drive, Elizabethtown, PA, 17022, USA
| | - Jeffrey A Rood
- Department of Chemistry & Biochemistry, Elizabethtown College, One Alpha Drive, Elizabethtown, PA, 17022, USA
| | - Kristi A Kneas
- Department of Chemistry & Biochemistry, Elizabethtown College, One Alpha Drive, Elizabethtown, PA, 17022, USA.
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Samigullin DV, Khaziev EF, Zhilyakov NV, Sudakov IA, Bukharaeva EA, Nikolsky EE. Calcium Transient Registration in Response to Single Stimulation and During Train of Pulses in Mouse Neuromuscular Junction. BIONANOSCIENCE 2016. [DOI: 10.1007/s12668-016-0318-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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29
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Calcium signaling in human pluripotent stem cells. Cell Calcium 2016; 59:117-23. [PMID: 26922096 DOI: 10.1016/j.ceca.2016.01.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 01/14/2016] [Accepted: 01/19/2016] [Indexed: 01/24/2023]
Abstract
Human pluripotent stem cells provide new tools for developmental and pharmacological studies as well as for regenerative medicine applications. Calcium homeostasis and ligand-dependent calcium signaling are key components of major cellular responses, including cell proliferation, differentiation or apoptosis. Interestingly, these phenomena have not been characterized in detail as yet in pluripotent human cell sates. Here we review the methods applicable for studying both short- and long-term calcium responses, focusing on the expression of fluorescent calcium indicator proteins and imaging methods as applied in pluripotent human stem cells. We discuss the potential regulatory pathways involving calcium responses in hPS cells and compare these to the implicated pathways in mouse PS cells. A recent development in the stem cell field is the recognition of so called "naïve" states, resembling the earliest potential forms of stem cells during development, as well as the "fuzzy" stem cells, which may be alternative forms of pluripotent cell types, therefore we also discuss the potential role of calcium homeostasis in these PS cell types.
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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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Jaafari N, De Waard M, Canepari M. Imaging fast calcium currents beyond the limitations of electrode techniques. Biophys J 2015; 107:1280-8. [PMID: 25229136 DOI: 10.1016/j.bpj.2014.07.059] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 06/06/2014] [Accepted: 07/30/2014] [Indexed: 10/24/2022] Open
Abstract
The current understanding of Ca(2+) channel function is derived from the use of the patch-clamp technique. In particular, the measurement of fast cellular Ca(2+) currents is routinely achieved using whole-cell voltage-clamp recordings. However, this experimental approach is not applicable to the study of local native Ca(2+) channels during physiological changes of membrane potential in complex cells, since the voltage-clamp configuration constrains the membrane potential to a given value. Here, we report for the first time to our knowledge that Ca(2+) currents from individual cells can be quantitatively measured beyond the limitations of the voltage-clamp approach using fast Ca(2+) imaging with low-affinity indicators. The optical measurement of the Ca(2+) current was correlated with the membrane potential, simultaneously measured with a voltage-sensitive dye to investigate the activation of Ca(2+) channels along the apical dendrite of the CA1 hippocampal pyramidal neuron during the back-propagation of an action potential. To validate the method, we analyzed the voltage dependence of high- and low-voltage-gated Ca(2+) channels. In particular, we measured the Ca(2+) current component mediated by T-type channels, and we investigated the mechanisms of recovery from inactivation of these channels. This method is expected to become a reference approach to investigate Ca(2+) channels in their native physiological environment.
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Affiliation(s)
- Nadia Jaafari
- Institut national de la santé et de la recherche médicale, Grenoble Institute of Neuroscience, Grenoble, France; Université Joseph Fourier, Laboratoire Interdisciplinare de Physique (Centre National de la Recherche Scientifique UMR 5588), France; Laboratories of Excellence, Ion Channel Science and Therapeutics, France
| | - Michel De Waard
- Institut national de la santé et de la recherche médicale, Grenoble Institute of Neuroscience, Grenoble, France; Laboratories of Excellence, Ion Channel Science and Therapeutics, France
| | - Marco Canepari
- Institut national de la santé et de la recherche médicale, Grenoble Institute of Neuroscience, Grenoble, France; Université Joseph Fourier, Laboratoire Interdisciplinare de Physique (Centre National de la Recherche Scientifique UMR 5588), France; Laboratories of Excellence, Ion Channel Science and Therapeutics, France.
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Abstract
The technique of dual-wavelength ratio fluorescence microscopy provides a powerful tool to measure organellar pH. Unlike single-wavelength measurements, this method is unaffected by changes in focal plane, dye volume, and fluorophore bleaching, providing a quantitative and dynamic readout of the pH of subcellular compartments. This chapter describes the application of dual-wavelength ratio fluorescence microscopy to the measurement of lysosomal pH, highlighting its advantages and limitations. Probe selection, calibration methods, and salient aspects of the required hardware are discussed in detail.
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Affiliation(s)
- Johnathan Canton
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario, M5G 0A4
| | - Sergio Grinstein
- Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, M5C 1N8, Canada
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Badura A, Sun XR, Giovannucci A, Lynch LA, Wang SSH. Fast calcium sensor proteins for monitoring neural activity. NEUROPHOTONICS 2014; 1:025008. [PMID: 25558464 PMCID: PMC4280659 DOI: 10.1117/1.nph.1.2.025008] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 09/12/2014] [Accepted: 09/23/2014] [Indexed: 05/18/2023]
Abstract
A major goal of the BRAIN Initiative is the development of technologies to monitor neuronal network activity during active information processing. Toward this goal, genetically encoded calcium indicator proteins have become widely used for reporting activity in preparations ranging from invertebrates to awake mammals. However, slow response times, the narrow sensitivity range of Ca2+ and in some cases, poor signal-to-noise ratio still limit their usefulness. Here, we review recent improvements in the field of neural activity-sensitive probe design with a focus on the GCaMP family of calcium indicator proteins. In this context, we present our newly developed Fast-GCaMPs, which have up to 4-fold accelerated off-responses compared with the next-fastest GCaMP, GCaMP6f. Fast-GCaMPs were designed by destabilizing the association of the hydrophobic pocket of calcium-bound calmodulin with the RS20 binding domain, an intramolecular interaction that protects the green fluorescent protein chromophore. Fast-GCaMP6f-RS06 and Fast-GCaMP6f-RS09 have rapid off-responses in stopped-flow fluorimetry, in neocortical brain slices, and in the intact cerebellum in vivo. Fast-GCaMP6f variants should be useful for tracking action potentials closely spaced in time, and for following neural activity in fast-changing compartments, such as axons and dendrites. Finally, we discuss strategies that may allow tracking of a wider range of neuronal firing rates and improve spike detection.
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Affiliation(s)
- Aleksandra Badura
- Princeton University, Princeton Neuroscience Institute and Department of Molecular Biology, Princeton, New Jersey 08544, United States
| | - Xiaonan Richard Sun
- Princeton University, Princeton Neuroscience Institute and Department of Molecular Biology, Princeton, New Jersey 08544, United States
| | - Andrea Giovannucci
- Princeton University, Princeton Neuroscience Institute and Department of Molecular Biology, Princeton, New Jersey 08544, United States
| | - Laura A. Lynch
- Princeton University, Princeton Neuroscience Institute and Department of Molecular Biology, Princeton, New Jersey 08544, United States
| | - Samuel S.-H. Wang
- Princeton University, Princeton Neuroscience Institute and Department of Molecular Biology, Princeton, New Jersey 08544, United States
- Address all correspondence to: Sam Wang, E-mail:
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Carter KP, Young AM, Palmer AE. Fluorescent sensors for measuring metal ions in living systems. Chem Rev 2014; 114:4564-601. [PMID: 24588137 PMCID: PMC4096685 DOI: 10.1021/cr400546e] [Citation(s) in RCA: 1540] [Impact Index Per Article: 154.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Indexed: 02/06/2023]
Affiliation(s)
- Kyle P. Carter
- Department
of Chemistry and
Biochemistry, BioFrontiers Institute, University
of Colorado, UCB 596,
3415 Colorado AvenueBoulder, Colorado 80303, United
States
| | - Alexandra M. Young
- Department
of Chemistry and
Biochemistry, BioFrontiers Institute, University
of Colorado, UCB 596,
3415 Colorado AvenueBoulder, Colorado 80303, United
States
| | - Amy E. Palmer
- Department
of Chemistry and
Biochemistry, BioFrontiers Institute, University
of Colorado, UCB 596,
3415 Colorado AvenueBoulder, Colorado 80303, United
States
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Castillo-Badillo JA, Cabrera-Wrooman A, García-Sáinz JA. Visualizing G protein-coupled receptors in action through confocal microscopy techniques. Arch Med Res 2014; 45:283-93. [PMID: 24751328 DOI: 10.1016/j.arcmed.2014.03.009] [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] [Received: 10/31/2013] [Accepted: 03/26/2014] [Indexed: 01/21/2023]
Abstract
G protein-coupled receptors constitute one of the most abundant entities in cellular communication. Elucidation of their structure and function as well as of their regulation began 30-40 years ago and the advance has markedly increased during the last 15 years. They participate in a plethora of cell functions such as regulation of metabolic fluxes, contraction, secretion, differentiation, or proliferation, and in essentially all activities of our organism; these receptors are targets of a large proportion of prescribed and illegal drugs. Fluorescence techniques have been used to study receptors for many years. The experimental result was usually a two-dimensional (2D) micrograph. Today, the result can be a spatiotemporal (four-dimensional, 4D) movie. Advances in microscopy, fluorescent protein design, and computer-assisted analysis have been of great importance to increase our knowledge on receptor regulation and function and create opportunities for future research. In this review we briefly depict the state of the art of the G protein-coupled receptor field and the methodologies used to study G protein-coupled receptor location, trafficking, dimerization, and other types of receptor-protein interaction. Fluorescence techniques now permit the capture of receptor images with high resolution and, together with a variety of fluorescent dyes that color organelles (such as the plasma membrane or the nucleus) or the cytoskeleton, allow researchers to obtain a much clearer idea of what is taking place at the cellular level. These developments are changing the way we explore cell communication and signal transduction, permitting deeper understanding of the physiological and pathophysiological processes.
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Affiliation(s)
- Jean A Castillo-Badillo
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., Mexico
| | | | - J Adolfo García-Sáinz
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., Mexico.
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Mattox TA, Young ME, Rubel CE, Spaniel C, Rodríguez JE, Grevengoed TJ, Gautel M, Xu Z, Anderson EJ, Willis MS. MuRF1 activity is present in cardiac mitochondria and regulates reactive oxygen species production in vivo. J Bioenerg Biomembr 2014; 46:173-87. [PMID: 24733503 DOI: 10.1007/s10863-014-9549-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Accepted: 03/19/2014] [Indexed: 01/10/2023]
Abstract
MuRF1 is a previously reported ubiquitin-ligase found in striated muscle that targets troponin I and myosin heavy chain for degradation. While MuRF1 has been reported to interact with mitochondrial substrates in yeast two-hybrid studies, no studies have identified MuRF1's role in regulating mitochondrial function to date. In the present study, we measured cardiac mitochondrial function from isolated permeabilized muscle fibers in previously phenotyped MuRF1 transgenic and MuRF1-/- mouse models to determine the role of MuRF1 in intermediate energy metabolism and ROS production. We identified a significant decrease in reactive oxygen species production in cardiac muscle fibers from MuRF1 transgenic mice with increased α-MHC driven MuRF1 expression. Increased MuRF1 expression in ex vivo and in vitro experiments revealed no alterations in the respiratory chain complex I and II function. Working perfusion experiments on MuRF1 transgenic hearts demonstrated significant changes in glucose oxidation. However, total oxygen consumption was decreased [corrected]. This data provides evidence for MuRF1 as a novel regulator of cardiac ROS, offering another mechanism by which increased MuRF1 expression may be cardioprotective in ischemia reperfusion injury, in addition to its inhibition of apoptosis via proteasome-mediate degradation of c-Jun. The lack of mitochondrial function phenotype identified in MuRF1-/- hearts may be due to the overlapping interactions of MuRF1 and MuRF2 with energy regulating proteins found by yeast two-hybrid studies reported here, implying a duplicity in MuRF1 and MuRF2's regulation of mitochondrial function.
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Affiliation(s)
- Taylor A Mattox
- Department of Pharmacology, East Carolina University, Greenville, NC, USA
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37
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Matkó J, Mátyus L, Szöllösi J, Bene L, Jenei A, Nagy P, Bodnár A, Damjanovich S. Analysis of cell surface molecular distributions and cellular signaling by flow cytometry. J Fluoresc 2013; 4:303-14. [PMID: 24233604 DOI: 10.1007/bf01881445] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/1993] [Indexed: 11/28/2022]
Abstract
Flow cytometry is a fast analysis and separation method for large cell populations, based on collection and processing of optical signals gained on a cell-by-cell basis. These optical signals are scattered light and fluorescence. Owing to its unique potential ofStatistical data analysis and sensitive monitoring of (micro)heterogeneities in large cell populations, flow cytometry-in combination with microscopic imaging techniques-is a powerful tool to study molecular details of cellular signal transduction processes as well. The method also has a widespread clinical application, mostly in analysis of lymphocyte subpopulations for diagnostic (or research) purposes in diseases related to the immune system. A special application of flow cytometry is the mapping of molecular interactions (proximity relationships between membrane proteins) at the cell surface, on a cell-by-cell basis. We developed two approaches to study such questions; both are based ondistance-dependent quenching of excited state fluorophores (donors) by fluorescent or dark (nitroxide radical) acceptors via Förstertype dipole-dipole resonance energy transfer (FRET) and long-range electron transfer (LRET) mechanisms, respectively. A critical evaluation of these methods using donor- or acceptor-conjugated monoclonal antibodies (or their Fab fragments) to select the appropriate cell surface receptor or antigen will be presented in comparison with other approaches for similar purposes. The applicability of FRET and LRET for two-dimensional antigen mapping as well as for detection of conformational changes in extracellular domains of membrane-bound proteins is discussed and illustrated by examples of several lymphoma cell lines. Another special application area of flow cytometry is the analysis of different aspects of cellular signal transduction, e.g., changes of intracellular ion (Ca(2+), H(+), Na(+)) concentrations, regulation of ion channel activities, or more complex physiological responses of cell to external stimuli via correlated fluorescence and scatter signal analysis, on a cell-by-cell basis. This way different signaling events such as changes in membrane permeability, membrane potential, cell size and shape, ion distribution, cell density, chromatin structure, etc., can be easily and quickly monitored over large cell populations with the advantage of revealing microheterogeneities in the cellular responses. Flow cytometry also offers the possibility to follow the kinetics of slow (minute- and hour-scale) biological processes in cell populations. These applications are illustrated by the example of complex flow cytometric analysis of signaling in extracellular ATP-triggered apoptosis (programmed cell death) of murine thymic lymphocytes.
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Affiliation(s)
- J Matkó
- Department of Biophysics, University School of Medicine, 4012, Debrecen, Hungary
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38
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Fisher-Wellman KH, Mattox TA, Thayne K, Katunga LA, La Favor JD, Neufer PD, Hickner RC, Wingard CJ, Anderson EJ. Novel role for thioredoxin reductase-2 in mitochondrial redox adaptations to obesogenic diet and exercise in heart and skeletal muscle. J Physiol 2013; 591:3471-86. [PMID: 23613536 DOI: 10.1113/jphysiol.2013.254193] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Increased fatty acid availability and oxidative stress are physiological consequences of exercise (Ex) and a high-fat, high-sugar (HFHS) diet. Despite these similarities, the global effects of Ex are beneficial, whereas HFHS diets are largely deleterious to the cardiovascular system. The reasons for this disparity are multifactorial and incompletely understood. We hypothesized that differences in redox adaptations following HFHS diet in comparison to exercise may underlie this disparity, particularly in mitochondria. Our objective in this study was to determine mechanisms by which heart and skeletal muscle (red gastrocnemius, RG) mitochondria experience differential redox adaptations to 12 weeks of HFHS diet and/or exercise training (Ex) in rats. Surprisingly, both HFHS feeding and Ex led to contrasting effects in heart and RG, in that mitochondrial H2O2 decreased in heart but increased in RG following both HFHS diet and Ex, in comparison to sedentary animals fed a control diet. These differences were determined to be due largely to increased antioxidant/anti-inflammatory enzymes in the heart following the HFHS diet, which did not occur in RG. Specifically, upregulation of mitochondrial thioredoxin reductase-2 occurred with both HFHS and Ex in the heart, but only with Ex in RG, and systematic evaluation of this enzyme revealed that it is critical for suppressing mitochondrial H2O2 during fatty acid oxidation. These findings are novel and important in that they illustrate the unique ability of the heart to adapt to oxidative stress imposed by HFHS diet, in part through upregulation of thioredoxin reductase-2. Furthermore, upregulation of thioredoxin reductase-2 plays a critical role in preserving the mitochondrial redox status in the heart and skeletal muscle with exercise.
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Martinez-Zaguilan R, Tompkins LS, Gillies RJ, Lynch RM. Simultaneous analysis of intracellular pH and Ca²⁺ from cell populations. Methods Mol Biol 2013; 937:253-71. [PMID: 23007592 DOI: 10.1007/978-1-62703-086-1_16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Although changes in both pH(in) and [Ca(2+)](i) have been observed in response to a variety of agonists, it is not clear whether these ionic events work independently or are coordinated to lead to a specific physiological response. One of the fundamental problems in studying these ionic events is that changes in pH(in) modify Ca(2+) regulatory mechanisms and changes in Ca(2+) may modify pH regulation. It is desirable to use a technique that allows concomitant monitoring of these two ions in cell populations with high time resolution. Furthermore, like many Ca(2+) binding proteins, all Ca(2+)-sensitive fluoroprobes are inherently sensitive to pH owing to competition of H(+) for the Ca(2+)-binding sites. This chapter describes experimental paradigms that provide optimum conditions for simultaneous measurement of pH from the fluorescence emission of snarf-1, and Ca(2+) using fura-2. The fluorescence spectra of these compounds are sufficiently different to allow simultaneous measurement of pH and Ca(2+) both in vitro and in vivo. Moreover, the ratio of the H(+)-sensitive wavelengths of snarf-1 is unaffected by Ca(2+), or the concomitant presence of fura-2 in cells. Although the fluorescence ratio of fura-2 is insensitive to the presence of snarf-1, it is affected by pH, as indicated above. We describe procedures to correct for this effect and to obtain calibration parameters for fura-2 and snarf-1 required to facilitate analysis of pH and Ca(2+) concentrations within cell populations.
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Affiliation(s)
- Raul Martinez-Zaguilan
- Department of Physiology, Texas Tech University Health Sciences Center, Lubbock, TX, USA
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40
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Inami W, Viet NH, Miyakawa A, Kawata Y. Intracellular calcium ion concentration measurement using a phase-modulation fluorescence lifetime method with compensation for phase shift due to the presence of proteins. ANAL SCI 2013; 29:199-203. [PMID: 23400285 DOI: 10.2116/analsci.29.199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The calcium ion concentration in cells was measured by a phase-modulation fluorescence lifetime method with compensation for proteins. A high-accuracy measurement of the calcium ion concentration is best realized by fluorescence lifetime measurements, because the fluorescence lifetime is independent of the fluorescence intensity. The fluorescence intensity is easily varied by the scattering of excitation and emission light in cells, photobleaching, the concentration of fluorochromes, and wavelength dispersion of optical elements. A phase-modulation fluorescence lifetime measurement, however, provides high accuracy and precision, and can measure not only the calcium ion concentration, but also other ion concentrations, such as that of magnesium, sodium, and potassium. We have examined the phase-modulation fluorescence lifetime shift using protein compensation in cells, and have measured the calcium ion concentration in cells stimulated with bradykinin.
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Affiliation(s)
- Wataru Inami
- Division of Global Research Leaders, Shizuoka University, Hamamatsu, Shizuoka, Japan.
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41
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Jespersen L, Jakobsen M. USE OF FLOW CYTOMETRY FOR RAPID ESTIMATION OF INTRACELLULAR EVENTS IN BREWING YEASTS. JOURNAL OF THE INSTITUTE OF BREWING 2013. [DOI: 10.1002/j.2050-0416.1994.tb00837.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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42
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Monitoring ion activities in and around cells using ion-selective liquid-membrane microelectrodes. SENSORS 2013; 13:984-1003. [PMID: 23322102 PMCID: PMC3574717 DOI: 10.3390/s130100984] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 12/31/2012] [Accepted: 01/02/2013] [Indexed: 11/24/2022]
Abstract
Determining the effective concentration (i.e., activity) of ions in and around living cells is important to our understanding of the contribution of those ions to cellular function. Moreover, monitoring changes in ion activities in and around cells is informative about the actions of the transporters and/or channels operating in the cell membrane. The activity of an ion can be measured using a glass microelectrode that includes in its tip a liquid-membrane doped with an ion-selective ionophore. Because these electrodes can be fabricated with tip diameters that are less than 1 μm, they can be used to impale single cells in order to monitor the activities of intracellular ions. This review summarizes the history, theory, and practice of ion-selective microelectrode use and brings together a number of classic and recent examples of their usefulness in the realm of physiological study.
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43
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Chen YH, Lo WJ, Sung K. Synthesis, Photophysical Properties, and Application of o- and p-Amino Green Fluorescence Protein Synthetic Chromophores. J Org Chem 2012. [DOI: 10.1021/jo302050y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yi-Hui Chen
- Department
of Chemistry, National Cheng Kung University, Tainan, Taiwan
| | - Wei-Jen Lo
- Department
of Chemistry, National Cheng Kung University, Tainan, Taiwan
| | - Kuangsen Sung
- Department
of Chemistry, National Cheng Kung University, Tainan, Taiwan
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44
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Visualizing metal ions in cells: an overview of analytical techniques, approaches, and probes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1406-15. [PMID: 22521452 DOI: 10.1016/j.bbamcr.2012.04.001] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/02/2012] [Accepted: 04/03/2012] [Indexed: 01/01/2023]
Abstract
Quantifying the amount and defining the location of metal ions in cells and organisms are critical steps in understanding metal homeostasis and how dyshomeostasis causes or is a consequence of disease. A number of recent advances have been made in the development and application of analytical methods to visualize metal ions in biological specimens. Here, we briefly summarize these advances before focusing in more depth on probes for examining transition metals in living cells with high spatial and temporal resolution using fluorescence microscopy. This article is part of a Special Issue entitled: Cell Biology of Metals.
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45
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Aldehyde stress and up-regulation of Nrf2-mediated antioxidant systems accompany functional adaptations in cardiac mitochondria from mice fed n-3 polyunsaturated fatty acids. Biochem J 2012; 441:359-66. [PMID: 21880016 DOI: 10.1042/bj20110626] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Diets replete with n-3 PUFAs (polyunsaturated fatty acids) are known to have therapeutic potential for the heart, although a specifically defined duration of the n-3 PUFA diet required to achieve these effects remains unknown, as does their mechanism of action. The present study was undertaken to establish whether adaptations in mitochondrial function and stress tolerance in the heart is evident following short- (3 weeks) and long- (14 weeks) term dietary intervention of n-3 PUFAs, and to identify novel mechanisms by which these adaptations occur. Mitochondrial respiration [mO2 (mitochondrial O2)], H2O2 emission [mH2O2 (mitochondrial H2O2)] and Ca2+-retention capacity [mCa2+ (mitochondrial Ca2+)] were assessed in mouse hearts following dietary intervention. Mice fed n-3 PUFAs for 14 weeks showed significantly lower mH2O2 and greater mCa2+ compared with all other groups. However, no significant differences were observed after 3 weeks of the n-3 PUFA diet, or in mice fed on an HFC (high-fat control) diet enriched with vegetable shortening, containing almost no n-3 PUFAs, for 14 weeks. Interestingly, expression and activity of key enzymes involved in antioxidant and phase II detoxification pathways, all mediated by Nrf2 (nuclear factor E2-related factor 2), were elevated in hearts from mice fed the n-3 PUFA diet, but not hearts from mice fed the HFC diet, even at 3 weeks. This increase in antioxidant systems in hearts from mice fed the n-3 PUFA diet was paralleled by increased levels of 4-hydroxyhexenal protein adducts, an aldehyde formed from peroxidation of n-3 PUFAs. The findings of the present study demonstrate distinct time-dependent effects of n-3 PUFAs on mitochondrial function and antioxidant response systems in the heart. In addition, they are the first to provide direct evidence that non-enzymatic oxidation products of n-3 PUFAs may be driving mitochondrial and redox-mediated adaptations, thereby revealing a novel mechanism for n-3 PUFA action in the heart.
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Maschio MD, Beltramo R, De Stasi AM, Fellin T. Two-Photon Calcium Imaging in the Intact Brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:83-102. [DOI: 10.1007/978-94-007-2888-2_4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Darszon A, Nishigaki T, Beltran C, Treviño CL. Calcium Channels in the Development, Maturation, and Function of Spermatozoa. Physiol Rev 2011; 91:1305-55. [DOI: 10.1152/physrev.00028.2010] [Citation(s) in RCA: 243] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A proper dialogue between spermatozoa and the egg is essential for conception of a new individual in sexually reproducing animals. Ca2+ is crucial in orchestrating this unique event leading to a new life. No wonder that nature has devised different Ca2+-permeable channels and located them at distinct sites in spermatozoa so that they can help fertilize the egg. New tools to study sperm ionic currents, and image intracellular Ca2+ with better spatial and temporal resolution even in swimming spermatozoa, are revealing how sperm ion channels participate in fertilization. This review critically examines the involvement of Ca2+ channels in multiple signaling processes needed for spermatozoa to mature, travel towards the egg, and fertilize it. Remarkably, these tiny specialized cells can express exclusive channels like CatSper for Ca2+ and SLO3 for K+, which are attractive targets for contraception and for the discovery of novel signaling complexes. Learning more about fertilization is a matter of capital importance; societies face growing pressure to counteract rising male infertility rates, provide safe male gamete-based contraceptives, and preserve biodiversity through improved captive breeding and assisted conception initiatives.
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Affiliation(s)
- Alberto Darszon
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Takuya Nishigaki
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Carmen Beltran
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Claudia L. Treviño
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
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Zhou X, He P. Temporal and spatial correlation of platelet-activating factor-induced increases in endothelial [Ca²⁺]i, nitric oxide, and gap formation in intact venules. Am J Physiol Heart Circ Physiol 2011; 301:H1788-97. [PMID: 21873500 DOI: 10.1152/ajpheart.00599.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously demonstrated that platelet-activating factor (PAF)-induced increases in microvessel permeability were associated with endothelial gap formation and that the magnitude of peak endothelial intracellular Ca(2+) concentration ([Ca(2+)](i)) and nitric oxide (NO) production at the single vessel level determines the degree of the permeability increase. This study aimed to examine whether the magnitudes of PAF-induced peak endothelial [Ca(2+)](i), NO production, and gap formation are correlated at the individual endothelial cell level in intact rat mesenteric venules. Endothelial gaps were quantified by the accumulation of fluorescent microspheres at endothelial clefts using confocal imaging. Endothelial [Ca(2+)](i) was measured on fura-2- or fluo-4-loaded vessels, and 4,5-diaminofluorescein (DAF-2) was used for NO measurements. The results showed that increases in endothelial [Ca(2+)](i), NO production, and gap formation occurred in all endothelial cells when vessels were exposed to PAF but manifested a spatial heterogeneity in magnitudes among cells in each vessel. PAF-induced peak endothelial [Ca(2+)](i) preceded the peak NO production by 0.6 min at the cellular level, and the magnitudes of NO production and gap formation linearly correlated with that of the peak endothelial [Ca(2+)](i) in each cell, suggesting that the initial levels of endothelial [Ca(2+)](i) determine downstream NO production and gap formation. These results provide direct evidence from intact venules that inflammatory mediator-induced increases in microvessel permeability are associated with the generalized formation of endothelial gaps around all endothelial cells. The spatial differences in the molecular signaling that were initiated by the heterogeneous endothelial Ca(2+) response contribute to the heterogeneity in permeability increases along the microvessel wall during inflammation.
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Affiliation(s)
- Xueping Zhou
- Department of Physiology and Pharmacology, School of Medicine, West Virginia University, Morgantown, WV 26506-9229, USA
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Read ND, Allan WTG, Knight H, Knight MR, Malhó R, Russell A, Shacklock PS, Trewavas AJ. Imaging and measurement of cytosolic free calcium in plant and fungal cells. J Microsc 2011. [DOI: 10.1111/j.1365-2818.1992.tb01507.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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