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Gedeon JY, Pineda-Farias JB, Gold MS. In-Vivo Calcium Imaging of Sensory Neurons in the Rat Trigeminal Ganglion. J Vis Exp 2024:10.3791/65978. [PMID: 38407223 PMCID: PMC11139451 DOI: 10.3791/65978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2024] Open
Abstract
Genetically encoded calcium indicators (GECIs) enable imaging techniques to monitor changes in intracellular calcium in targeted cell populations. Their large signal-to-noise ratio makes GECIs a powerful tool for detecting stimulus-evoked activity in sensory neurons. GECIs facilitate population-level analysis of stimulus encoding with the number of neurons that can be studied simultaneously. This population encoding is most appropriately done in vivo. Dorsal root ganglia (DRG), which house the soma of sensory neurons innervating somatic and visceral structures below the neck, are used most extensively for in vivo imaging because these structures are accessed relatively easily. More recently, this technique was used in mice to study sensory neurons in the trigeminal ganglion (TG) that innervate oral and craniofacial structures. There are many reasons to study TG in addition to DRG, including the long list of pain syndromes specific to oral and craniofacial structures that appear to reflect changes in sensory neuron activity, such as trigeminal neuralgia. Mice are used most extensively in the study of DRG and TG neurons because of the availability of genetic tools. However, with differences in size, ease of handling, and potentially important species differences, there are reasons to study rat rather than mouse TG neurons. Thus, we developed an approach for imaging rat TG neurons in vivo. We injected neonatal pups (p2) intraperitoneally with an AAV encoding GCaMP6s, resulting in >90% infection of both TG and DRG neurons. TG was visualized in the adult following craniotomy and decortication, and changes in GCaMP6s fluorescence were monitored in TG neurons following stimulation of mandibular and maxillary regions of the face. We confirmed that increases in fluorescence were stimulus-evoked with peripheral nerve block. While this approach has many potential uses, we are using it to characterize the subpopulation(s) of TG neurons changed following peripheral nerve injury.
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Affiliation(s)
- Jeremy Y Gedeon
- Center for Neuroscience at the University of Pittsburgh; Department of Neurobiology, University of Pittsburgh School of Medicine; Pittsburgh Center for Pain Research, University of Pittsburgh
| | - Jorge Baruch Pineda-Farias
- Department of Neurobiology, University of Pittsburgh School of Medicine; Pittsburgh Center for Pain Research, University of Pittsburgh
| | - Michael S Gold
- Department of Neurobiology, University of Pittsburgh School of Medicine; Pittsburgh Center for Pain Research, University of Pittsburgh;
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2
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Brandalise F, Ramieri M, Pastorelli E, Priori EC, Ratto D, Venuti MT, Roda E, Talpo F, Rossi P. Role of Na +/Ca 2+ Exchanger (NCX) in Glioblastoma Cell Migration (In Vitro). Int J Mol Sci 2023; 24:12673. [PMID: 37628853 PMCID: PMC10454658 DOI: 10.3390/ijms241612673] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/07/2023] [Accepted: 08/08/2023] [Indexed: 08/27/2023] Open
Abstract
Glioblastoma (GBM) is the most malignant form of primary brain tumor. It is characterized by the presence of highly invasive cancer cells infiltrating the brain by hijacking neuronal mechanisms and interacting with non-neuronal cell types, such as astrocytes and endothelial cells. To enter the interstitial space of the brain parenchyma, GBM cells significantly shrink their volume and extend the invadopodia and lamellipodia by modulating their membrane conductance repertoire. However, the changes in the compartment-specific ionic dynamics involved in this process are still not fully understood. Here, using noninvasive perforated patch-clamp and live imaging approaches on various GBM cell lines during a wound-healing assay, we demonstrate that the sodium-calcium exchanger (NCX) is highly expressed in the lamellipodia compartment, is functionally active during GBM cell migration, and correlates with the overexpression of large conductance K+ channel (BK) potassium channels. Furthermore, a NCX blockade impairs lamellipodia formation and maintenance, as well as GBM cell migration. In conclusion, the functional expression of the NCX in the lamellipodia of GBM cells at the migrating front is a conditio sine qua non for the invasion strategy of these malignant cells and thus represents a potential target for brain tumor treatment.
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Affiliation(s)
| | - Martino Ramieri
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (M.R.); (E.P.); (E.C.P.); (D.R.); (M.T.V.)
| | - Emanuela Pastorelli
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (M.R.); (E.P.); (E.C.P.); (D.R.); (M.T.V.)
| | - Erica Cecilia Priori
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (M.R.); (E.P.); (E.C.P.); (D.R.); (M.T.V.)
| | - Daniela Ratto
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (M.R.); (E.P.); (E.C.P.); (D.R.); (M.T.V.)
| | - Maria Teresa Venuti
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (M.R.); (E.P.); (E.C.P.); (D.R.); (M.T.V.)
| | - Elisa Roda
- Laboratory of Clinical & Experimental Toxicology, Pavia Poison Centre, National Toxicology Information Centre, Toxicology Unit, Istituti Clinici Scientifici Maugeri IRCCS Pavia, 27100 Pavia, Italy;
| | - Francesca Talpo
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (M.R.); (E.P.); (E.C.P.); (D.R.); (M.T.V.)
| | - Paola Rossi
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (M.R.); (E.P.); (E.C.P.); (D.R.); (M.T.V.)
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3
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Trendafilova T, Adhikari K, Schmid AB, Patel R, Polgár E, Chisholm KI, Middleton SJ, Boyle K, Dickie AC, Semizoglou E, Perez-Sanchez J, Bell AM, Ramirez-Aristeguieta LM, Khoury S, Ivanov A, Wildner H, Ferris E, Chacón-Duque JC, Sokolow S, Saad Boghdady MA, Herchuelz A, Faux P, Poletti G, Gallo C, Rothhammer F, Bedoya G, Zeilhofer HU, Diatchenko L, McMahon SB, Todd AJ, Dickenson AH, Ruiz-Linares A, Bennett DL. Sodium-calcium exchanger-3 regulates pain "wind-up": From human psychophysics to spinal mechanisms. Neuron 2022; 110:2571-2587.e13. [PMID: 35705078 PMCID: PMC7613464 DOI: 10.1016/j.neuron.2022.05.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 03/31/2022] [Accepted: 05/16/2022] [Indexed: 11/17/2022]
Abstract
Repeated application of noxious stimuli leads to a progressively increased pain perception; this temporal summation is enhanced in and predictive of clinical pain disorders. Its electrophysiological correlate is "wind-up," in which dorsal horn spinal neurons increase their response to repeated nociceptor stimulation. To understand the genetic basis of temporal summation, we undertook a GWAS of wind-up in healthy human volunteers and found significant association with SLC8A3 encoding sodium-calcium exchanger type 3 (NCX3). NCX3 was expressed in mouse dorsal horn neurons, and mice lacking NCX3 showed normal, acute pain but hypersensitivity to the second phase of the formalin test and chronic constriction injury. Dorsal horn neurons lacking NCX3 showed increased intracellular calcium following repetitive stimulation, slowed calcium clearance, and increased wind-up. Moreover, virally mediated enhanced spinal expression of NCX3 reduced central sensitization. Our study highlights Ca2+ efflux as a pathway underlying temporal summation and persistent pain, which may be amenable to therapeutic targeting.
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Affiliation(s)
| | - Kaustubh Adhikari
- School of Mathematics and Statistics, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, UK; Department of Genetics, Evolution and Environment, University College London, London, UK; Department of Cell and Developmental Biology, University College London, London, UK
| | - Annina B Schmid
- Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
| | - Ryan Patel
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Erika Polgár
- School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
| | - Kim I Chisholm
- Wolfson Centre for Age-Related Diseases, King's College London, London, UK
| | - Steven J Middleton
- Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
| | - Kieran Boyle
- School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
| | - Allen C Dickie
- School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
| | | | | | - Andrew M Bell
- School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
| | | | - Samar Khoury
- McGill University and Genome Quebec Innovation Centre, Montreal, QC, Canada
| | - Aleksandar Ivanov
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Eleanor Ferris
- Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
| | - Juan-Camilo Chacón-Duque
- Department of Genetics, Evolution and Environment, University College London, London, UK; Centre for Palaeogenetics, Stockholm, Sweden; Department of Archaeology and Classical Studies, Stockholm University, Stockholm, Sweden
| | - Sophie Sokolow
- Laboratoire de Pharmacodynamie et de Thérapeutique Faculté de Médecine Université Libre de Bruxelles, Brussels, Belgium; School of Nursing, University of California, Los Angeles, Los Angeles, CA, USA
| | | | - André Herchuelz
- Laboratoire de Pharmacodynamie et de Thérapeutique Faculté de Médecine Université Libre de Bruxelles, Brussels, Belgium
| | - Pierre Faux
- CNRS, EFS, ADES, Aix-Marseille Université, Marseille, France
| | - Giovanni Poletti
- Unidad de Neurobiologia Molecular y Genética, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Carla Gallo
- Unidad de Neurobiologia Molecular y Genética, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | | | - Gabriel Bedoya
- GENMOL (Genética Molecular), Universidad de Antioquia, Medellin, Colombia
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland; Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Luda Diatchenko
- McGill University and Genome Quebec Innovation Centre, Montreal, QC, Canada
| | - Stephen B McMahon
- Wolfson Centre for Age-Related Diseases, King's College London, London, UK
| | - Andrew J Todd
- School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
| | - Anthony H Dickenson
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Andres Ruiz-Linares
- Department of Genetics, Evolution and Environment, University College London, London, UK; CNRS, EFS, ADES, Aix-Marseille Université, Marseille, France; Ministry of Education Key Laboratory of Contemporary Anthropology and Collaborative Innovation Center of Genetics and Development, School of Life Sciences and Human Phenome Institute, Fudan University, Shanghai, China.
| | - David L Bennett
- Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK.
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4
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Rodrigues T, Piccirillo S, Magi S, Preziuso A, Dos Santos Ramos V, Serfilippi T, Orciani M, Maciel Palacio Alvarez M, Luis Dos Santos Tersariol I, Amoroso S, Lariccia V. Control of Ca 2+ and metabolic homeostasis by the Na +/Ca 2+ exchangers (NCXs) in health and disease. Biochem Pharmacol 2022; 203:115163. [PMID: 35803319 DOI: 10.1016/j.bcp.2022.115163] [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: 04/01/2022] [Revised: 06/30/2022] [Accepted: 07/01/2022] [Indexed: 11/16/2022]
Abstract
Spatial and temporal control of calcium (Ca2+) levels is essential for the background rhythms and responses of living cells to environmental stimuli. Whatever other regulators a given cellular activity may have, localized and wider scale Ca2+ events (sparks, transients, and waves) are hierarchical determinants of fundamental processes such as cell contraction, excitability, growth, metabolism and survival. Different cell types express specific channels, pumps and exchangers to efficiently generate and adapt Ca2+ patterns to cell requirements. The Na+/Ca2+ exchangers (NCXs) in particular contribute to Ca2+ homeostasis by buffering intracellular Ca2+ loads according to the electrochemical gradients of substrate ions - i.e., Ca2+ and sodium (Na+) - and under a dynamic control of redundant regulatory processes. An interesting feature of NCX emerges from the strict relationship that connects transporter activity with cell metabolism: on the one hand NCX operates under constant control of ATP-dependent regulatory processes, on the other hand the ion fluxes generated through NCX provide mechanistic support for the Na+-driven uptake of glutamate and Ca2+ influx to fuel mitochondrial respiration. Proof of concept evidence highlights therapeutic potential of preserving a timed and balanced NCX activity in a growing rate of diseases (including excitability, neurodegenerative, and proliferative disorders) because of an improved ability of stressed cells to safely maintain ion gradients and mitochondrial bioenergetics. Here, we will summarize and review recent works that have focused on the pathophysiological roles of NCXs in balancing the two-way relationship between Ca2+ signals and metabolism.
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Affiliation(s)
- Tiago Rodrigues
- Center for Natural and Human Sciences (CCNH), Federal University of ABC (UFABC), Santo André, SP, Brazil.
| | - Silvia Piccirillo
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Simona Magi
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Alessandra Preziuso
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Vyctória Dos Santos Ramos
- Interdisciplinary Center for Biochemistry Investigation (CIIB), University of Mogi das Cruzes (UMC), Mogi das Cruzes, SP, Brazil
| | - Tiziano Serfilippi
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Monia Orciani
- Department of Clinical and Molecular Sciences, Histology, University "Politecnica delle Marche", Ancona, Italy.
| | - Marcela Maciel Palacio Alvarez
- Department of Biochemistry, São Paulo School of Medicine, Federal University of São Paulo (Unifesp) São Paulo, SP, Brazil
| | | | - Salvatore Amoroso
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Vincenzo Lariccia
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
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5
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Körner J, Lampert A. Functional subgroups of rat and human sensory neurons: a systematic review of electrophysiological properties. Pflugers Arch 2022; 474:367-385. [PMID: 35031856 PMCID: PMC8924089 DOI: 10.1007/s00424-021-02656-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 11/23/2021] [Accepted: 12/14/2021] [Indexed: 11/15/2022]
Abstract
Sensory neurons are responsible for the generation and transmission of nociceptive signals from the periphery to the central nervous system. They encompass a broadly heterogeneous population of highly specialized neurons. The understanding of the molecular choreography of individual subpopulations is essential to understand physiological and pathological pain states. Recently, it became evident that species differences limit transferability of research findings between human and rodents in pain research. Thus, it is necessary to systematically compare and categorize the electrophysiological data gained from human and rodent dorsal root ganglia neurons (DRGs). In this systematic review, we condense the available electrophysiological data defining subidentities in human and rat DRGs. A systematic search on PUBMED yielded 30 studies on rat and 3 studies on human sensory neurons. Defined outcome parameters included current clamp, voltage clamp, cell morphology, pharmacological readouts, and immune reactivity parameters. We compare evidence gathered for outcome markers to define subgroups, offer electrophysiological parameters for the definition of neuronal subtypes, and give a framework for the transferability of electrophysiological findings between species. A semiquantitative analysis revealed that for rat DRGs, there is an overarching consensus between studies that C-fiber linked sensory neurons display a lower action potential threshold, higher input resistance, a larger action potential overshoot, and a longer afterhyperpolarization duration compared to other sensory neurons. They are also more likely to display an infliction point in the falling phase of the action potential. This systematic review points out the need of more electrophysiological studies on human sensory neurons.
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Affiliation(s)
- Jannis Körner
- Institute of Physiology, Uniklinik RWTH Aachen, Pauwelsstrasse 30, 52074, Aachen, Germany.,Clinic of Anesthesiology, Uniklinik RWTH Aachen, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Angelika Lampert
- Institute of Physiology, Uniklinik RWTH Aachen, Pauwelsstrasse 30, 52074, Aachen, Germany.
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6
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Cracking the code of sodium/calcium exchanger (NCX) gating: Old and new complexities surfacing from the deep web of secondary regulations. Cell Calcium 2020; 87:102169. [PMID: 32070925 DOI: 10.1016/j.ceca.2020.102169] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 01/29/2020] [Accepted: 01/29/2020] [Indexed: 12/14/2022]
Abstract
Cell membranes spatially define gradients that drive the complexity of biological signals. To guarantee movements and exchanges of solutes between compartments, membrane transporters negotiate the passages of ions and other important molecules through lipid bilayers. The Na+/Ca2+ exchangers (NCXs) in particular play central roles in balancing Na+ and Ca2+ fluxes across diverse proteolipid borders in all eukaryotic cells, influencing cellular functions and fate by multiple means. To prevent progression from balance to disease, redundant regulatory mechanisms cooperate at multiple levels (transcriptional, translational, and post-translational) and guarantee that the activities of NCXs are finely-tuned to cell homeostatic requirements. When this regulatory network is disturbed by pathological forces, cells may approach the end of life. In this review, we will discuss the main findings, controversies and open questions about regulatory mechanisms that control NCX functions in health and disease.
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Mandge D, Manchanda R. A biophysically detailed computational model of urinary bladder small DRG neuron soma. PLoS Comput Biol 2018; 14:e1006293. [PMID: 30020934 PMCID: PMC6066259 DOI: 10.1371/journal.pcbi.1006293] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 07/30/2018] [Accepted: 06/11/2018] [Indexed: 12/13/2022] Open
Abstract
Bladder small DRG neurons, which are putative nociceptors pivotal to urinary bladder function, express more than a dozen different ionic membrane mechanisms: ion channels, pumps and exchangers. Small-conductance Ca2+-activated K+ (SKCa) channels which were earlier thought to be gated solely by intracellular Ca2+ concentration ([Ca]i) have recently been shown to exhibit inward rectification with respect to membrane potential. The effect of SKCa inward rectification on the excitability of these neurons is unknown. Furthermore, studies on the role of KCa channels in repetitive firing and their contributions to different types of afterhyperpolarization (AHP) in these neurons are lacking. In order to study these phenomena, we first constructed and validated a biophysically detailed single compartment model of bladder small DRG neuron soma constrained by physiological data. The model includes twenty-two major known membrane mechanisms along with intracellular Ca2+ dynamics comprising Ca2+ diffusion, cytoplasmic buffering, and endoplasmic reticulum (ER) and mitochondrial mechanisms. Using modelling studies, we show that inward rectification of SKCa is an important parameter regulating neuronal repetitive firing and that its absence reduces action potential (AP) firing frequency. We also show that SKCa is more potent in reducing AP spiking than the large-conductance KCa channel (BKCa) in these neurons. Moreover, BKCa was found to contribute to the fast AHP (fAHP) and SKCa to the medium-duration (mAHP) and slow AHP (sAHP). We also report that the slow inactivating A-type K+ channel (slow KA) current in these neurons is composed of 2 components: an initial fast inactivating (time constant ∼ 25-100 ms) and a slow inactivating (time constant ∼ 200-800 ms) current. We discuss the implications of our findings, and how our detailed model can help further our understanding of the role of C-fibre afferents in the physiology of urinary bladder as well as in certain disorders.
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Affiliation(s)
- Darshan Mandge
- Computational Neurophysiology Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India 400076
| | - Rohit Manchanda
- Computational Neurophysiology Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India 400076
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8
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Lariccia V, Amoroso S. Calcium- and ATP-dependent regulation of Na/Ca exchange function in BHK cells: Comparison of NCX1 and NCX3 exchangers. Cell Calcium 2018; 73:95-103. [PMID: 29705719 DOI: 10.1016/j.ceca.2018.04.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 04/16/2018] [Indexed: 12/27/2022]
Abstract
Na+/Ca2+ exchangers (NCX) mediate bidirectional Ca2+ fluxes across cell membranes and contribute to Ca2+ homeostasis in many cell types. Exchangers are regulated by gating reactions that depend on Na+ and Ca2+ binding to transport and regulatory sites. A Na+i-dependent inactivation is prominent in all isoforms, whereas Ca2+i-dependent regulation varies among isoforms. Here we characterize new details of NCX operation and describe differences and similarities between NCX3 and NCX1 regulation by intracellular Ca2+ and ATP. To compare isoforms, we employed BHK cells expressing NCX3 or NCX1 constitutively and exchange activity was analysed in whole-cell and excised patch recordings under "zero-trans" conditions (i.e., with only one transported ion species on each side). Using BHK cells with low cytoplasmic Ca2+ buffering, outward (reverse) currents, reflecting Ca2+ influx, are activated by applying extracellular Ca2+ (Cao) in the presence of Na+ on the cytoplasmic side. When firstly activated, peak outward NCX3 currents rapidly decay over seconds and then typically develop a secondary transient peak with slower kinetics, until Cao removal abolishes all outward current. The delayed rise of outward current is the signature of an activating process since peak outward NCX3 currents elicited at subsequent Cao bouts remain stimulated for minutes and slower decline towards a non-zero level during continued Cao application. Secondary transient peaks and current stimulation are suppressed by increasing the intracellular Ca2+ buffer capacity or by replacing cytoplasmic ATP with the analogues AMP-PNP or ATPγS. In BHK cells expressing NCX1, outward currents activated under identical settings decay to a steady-state level during single Cao application and are significantly larger, causing strong and long-lived run down of subsequent outward currents. NCX1 current run down is not prevented by increasing cytoplasmic Ca2+ buffering but secondary transient peaks in the outward current profile can be resolved in the presence of ATP. Finally, inward currents recorded in patches excised from NCX3-expressing cells reveal a proteolysis-sensitive, Ca-dependent inactivation process that is unusual for NCX1 forward activity. Together, our results suggest that NCX function is regulated more richly than appreciated heretofore, possibly including processes that are lost in excised membrane patches.
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Affiliation(s)
- Vincenzo Lariccia
- Department of Biomedical Science and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
| | - Salvatore Amoroso
- Department of Biomedical Science and Public Health, School of Medicine, University "Politecnica delle Marche", Ancona, Italy.
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9
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Yilmaz E, Watkins SC, Gold MS. Paclitaxel-induced increase in mitochondrial volume mediates dysregulation of intracellular Ca 2+ in putative nociceptive glabrous skin neurons from the rat. Cell Calcium 2017; 62:16-28. [PMID: 28109678 DOI: 10.1016/j.ceca.2017.01.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 01/10/2017] [Accepted: 01/11/2017] [Indexed: 01/14/2023]
Abstract
We have recently demonstrated that in a rat model of chemotherapy-induced peripheral neuropathy (CIPN), there is a significant decrease in the duration of the depolarization-evoked Ca2+ transient in small diameter, IB4+, and capsaicin-responsive neurons innervating the glabrous skin of the hindpaw. This change was specific to the transient duration and significantly smaller if not undetectable in neurons innervating the dorsal skin of the hindpaw or the skin of the inner thigh. Given the importance of mitochondria in intracellular Ca2+ regulation and the findings of chemotherapy-associated increase in mitotoxicity along the sensory neuron axons, we hypothesized that CIPN is due to both increases and decreases in mitochondria function, with changes manifest in distinct subpopulations of afferents. To begin to test this hypothesis, we used confocal microscopy and Ca2+ imaging in combination with pharmacological manipulations to study paclitaxel-induced changes in retrograde tracer-labeled neurons from naïve, vehicle-treated, and paclitaxel-treated rats. Paclitaxel treatment was not associated with decreased mitochondrial membrane potential or increased superoxide levels in the somata of putative nociceptive glabrous skin neurons. However, it was associated with significant increases in the relative contribution of mitochondria to the control of the evoked Ca2+ transient duration in putative nociceptive glabrous skin neurons, as well as increases in mitotracker and Tom20 staining which reflected an increase in mitochondrial volume. Furthermore, the relative contribution of the sarco-endoplasmic reticulum Ca2+ ATPase to the regulation of the duration of the depolarization evoked Ca2+ transient was also increased in this subpopulation of neurons from paclitaxel treated rats. Our results indicate that the paclitaxel-induced decrease in the duration of the evoked Ca2+ transient is due to both direct and indirect influences of mitochondria. It remains to be determined if and how these changes contribute to the manifestation of CIPN.
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Affiliation(s)
- Eser Yilmaz
- Center for Neuroscience University of Pittsburgh, United States; Departments of Neurobiology, University of Pittsburgh School of Medicine, United States
| | - Simon C Watkins
- Cell Biology, University of Pittsburgh School of Medicine, United States; Immunology, University of Pittsburgh School of Medicine, United States
| | - Michael S Gold
- Center for Neuroscience University of Pittsburgh, United States; Departments of Neurobiology, University of Pittsburgh School of Medicine, United States.
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10
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Yilmaz E, Gold MS. Paclitaxel-induced increase in NCX activity in subpopulations of nociceptive afferents: A protective mechanism against chemotherapy-induced peripheral neuropathy? Cell Calcium 2016; 60:25-31. [PMID: 27166151 PMCID: PMC4907840 DOI: 10.1016/j.ceca.2016.04.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 04/11/2016] [Accepted: 04/28/2016] [Indexed: 01/14/2023]
Abstract
We recently demonstrated, in a rat model of chemotherapy-induced peripheral neuropathy (CIPN), that there is a significant decrease in the duration of the depolarization-evoked Ca(2+) transient in isolated somata of putative nociceptive afferents innervating the glabrous skin of the hindpaw, but no change in transient magnitude or the resting concentration of intracellular Ca(2+) ([Ca(2+)]i). Because the Na(+)-Ca(2+) exchanger (NCX) only contributes to the regulation of the duration of the evoked Ca(2+) transient, in putative nociceptive dorsal root ganglion (DRG) neurons, we hypothesized that an increase in NCX activity underlies the CIPN-induced change in this subpopulation of neurons. Acutely dissociated retrogradely labeled sensory neurons from naïve, vehicle-, and paclitaxel-treated rats were studied with fura-2 based Ca(2+) imaging. There was no difference in the relative level of NCX activity between glabrous neurons from paclitaxel-treated or control rats. However, in contrast to the relatively large and long lasting Ca(2+) transients needed to evoke NCX activity in neurons from naïve rats, there was evidence of resting NCX activity in glabrous neurons from both vehicle- and paclitaxel-treated rats. More interestingly, there was a paclitaxel-induced increase in NCX activity in putative nociceptive neurons innervating the thigh, neurons in which there is no evidence of a change in the depolarization-induced Ca(2+) transient, or a body site in which there was a change in nociceptive threshold. Furthermore, while the majority of NCX activity in glabrous neurons is sensitive to the NCX3-preferring blocker KB-R7943, the increase in NCX activity in thigh neurons was resistant to KB-R7943 but sensitive to the NCX1-preferring blocker SEA0400. These results suggest that a mechanism(s) other than NCX underlies the paclitaxel-induced decrease in the duration of the evoked Ca(2+) transient in putative nociceptive glabrous skin neurons. However, the compensatory response to paclitaxel observed may also explain why only subpopulations of sensory neurons are impacted by paclitaxel, raising the intriguing possibility that CIPN is due to the failure of injured neurons to appropriately compensate for the deleterious consequences of this compound.
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Affiliation(s)
- Eser Yilmaz
- Center for Neuroscience, University of Pittsburgh, United States; Center for Pain Research, University of Pittsburgh School of Medicine, United States
| | - Michael S Gold
- Center for Neuroscience, University of Pittsburgh, United States; Center for Pain Research, University of Pittsburgh School of Medicine, United States; Department of Anesthesiology, University of Pittsburgh School of Medicine, United States.
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Zhang Z, David G. Stimulation-induced Ca(2+) influx at nodes of Ranvier in mouse peripheral motor axons. J Physiol 2015; 594:39-57. [PMID: 26365250 DOI: 10.1113/jp271207] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 09/03/2015] [Indexed: 01/26/2023] Open
Abstract
KEY POINTS In peripheral myelinated axons of mammalian spinal motor neurons, Ca(2+) influx was thought to occur only in pathological conditions such as ischaemia. Using Ca(2+) imaging in mouse large motor axons, we find that physiological stimulation with trains of action potentials transiently elevates axoplasmic [C(2+)] around nodes of Ranvier. These stimulation-induced [Ca(2+)] elevations require Ca(2+) influx, and are partially reduced by blocking T-type Ca(2+) channels (e.g. mibefradil) and by blocking the Na(+)/Ca(2+) exchanger (NCX), suggesting an important contribution of Ca(2+) influx via reverse-mode NCX activity. Acute disruption of paranodal myelin dramatically increases stimulation-induced [Ca(2+)] elevations around nodes by allowing activation of sub-myelin L-type (nimodipine-sensitive) Ca(2+) channels. The Ca(2+) that enters myelinated motor axons during normal activity is likely to contribute to several signalling pathways; the larger Ca(2+) influx that occurs following demyelination may contribute to the axonal degeneration that occurs in peripheral demyelinating diseases. Activity-dependent Ca(2+) signalling is well established for somata and terminals of mammalian spinal motor neurons, but not for their axons. Imaging of an intra-axonally injected fluorescent [Ca(2+)] indicator revealed that during repetitive action potential stimulation, [Ca(2+)] elevations localized to nodal regions occurred in mouse motor axons from ventral roots, phrenic nerve and intramuscular branches. These [Ca(2+)] elevations (∼ 0.1 μm with stimulation at 50 Hz, 10 s) were blocked by removal of Ca(2+) from the extracellular solution. Effects of pharmacological blockers indicated contributions from both T-type Ca(2+) channels and reverse mode Na(+)/Ca(2+) exchange (NCX). Acute disruption of paranodal myelin (by stretch or lysophosphatidylcholine) increased the stimulation-induced [Ca(2+)] elevations, which now included a prominent contribution from L-type Ca(2+) channels. These results suggest that the peri-nodal axolemma of motor axons includes multiple pathways for stimulation-induced Ca(2+) influx, some active in normally-myelinated axons (T-type channels, NCX), others active only when exposed by myelin disruption (L-type channels). The modest axoplasmic peri-nodal [Ca(2+)] elevations measured in intact motor axons might mediate local responses to axonal activation. The larger [Ca(2+) ] elevations measured after myelin disruption might, over time, contribute to the axonal degeneration observed in peripheral demyelinating neuropathies.
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Affiliation(s)
- Zhongsheng Zhang
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA
| | - Gavriel David
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA.,Neuroscience Program, University of Miami Miller School of Medicine, PO Box 011351, Miami, FL, 33101, USA
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Trafficking of Na+/Ca2+ exchanger to the site of persistent inflammation in nociceptive afferents. J Neurosci 2015; 35:8423-32. [PMID: 26041911 DOI: 10.1523/jneurosci.3597-14.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Persistent inflammation results in an increase in the amplitude and duration of depolarization-evoked Ca(2+) transients in putative nociceptive afferents. Previous data indicated that these changes were the result of neither increased neuronal excitability nor an increase in the amplitude of depolarization. Subsequent data also ruled out an increase in voltage-gated Ca(2+) currents and recruitment of Ca(2+)-induced Ca(2+) release. Parametric studies indicated that the inflammation-induced increase in the duration of the evoked Ca(2+) transient required a relatively large and long-lasting increase in the concentration of intracellular Ca(2+) implicating the Na(+)/Ca(2+) exchanger (NCX), a major Ca(2+) extrusion mechanism activated with high intracellular Ca(2+) loads. The contribution of NCX to the inflammation-induced increase in the evoked Ca(2+) transient in rat sensory neurons was tested using fura-2 AM imaging and electrophysiological recordings. Changes in NCX expression and protein were assessed with real-time PCR and Western blot analysis, respectively. An inflammation-induced decrease in NCX activity was observed in a subpopulation of putative nociceptive neurons innervating the site of inflammation. The time course of the decrease in NCX activity paralleled that of the inflammation-induced changes in nociceptive behavior. The change in NCX3 in the cell body was associated with a decrease in NCX3 protein in the ganglia, an increase in the peripheral nerve (sciatic) yet no change in the central root. This single response to inflammation is associated with changes in at least three different segments of the primary afferent, all of which are likely to contribute to the dynamic response to persistent inflammation.
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