1
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Steinert JR, Amal H. The contribution of an imbalanced redox signalling to neurological and neurodegenerative conditions. Free Radic Biol Med 2023; 194:71-83. [PMID: 36435368 DOI: 10.1016/j.freeradbiomed.2022.11.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/17/2022] [Accepted: 11/22/2022] [Indexed: 11/25/2022]
Abstract
Nitric oxide and other redox active molecules such as oxygen free radicals provide essential signalling in diverse neuronal functions, but their excess production and insufficient scavenging induces cytotoxic redox stress which is associated with numerous neurodegenerative and neurological conditions. A further component of redox signalling is mediated by a homeostatic regulation of divalent metal ions, the imbalance of which contributes to neuronal dysfunction. Additional antioxidant molecules such as glutathione and enzymes such as super oxide dismutase are involved in maintaining a physiological redox status within neurons. When cellular processes are perturbed and generation of free radicals overwhelms the antioxidants capacity of the neurons, a resulting redox damage leads to neuronal dysfunction and cell death. Cellular sources for production of redox-active molecules may include NADPH oxidases, mitochondria, cytochrome P450 and nitric oxide (NO)-generating enzymes, such as endothelial, neuronal and inducible NO synthases. Several neurodegenerative and developmental neurological conditions are associated with an imbalanced redox state as a result of neuroinflammatory processes leading to nitrosative and oxidative stress. Ongoing research aims at understanding the causes and consequences of such imbalanced redox homeostasis and its role in neuronal dysfunction.
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Affiliation(s)
- Joern R Steinert
- Division of Physiology, Pharmacology and Neuroscience, University of Nottingham, School of Life Sciences, Nottingham, NG7 2NR, UK.
| | - Haitham Amal
- Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel.
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2
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Abbott GW. Kv Channel Ancillary Subunits: Where Do We Go from Here? Physiology (Bethesda) 2022; 37:0. [PMID: 35797055 PMCID: PMC9394777 DOI: 10.1152/physiol.00005.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated potassium (Kv) channels each comprise four pore-forming α-subunits that orchestrate essential duties such as voltage sensing and K+ selectivity and conductance. In vivo, however, Kv channels also incorporate regulatory subunits-some Kv channel specific, others more general modifiers of protein folding, trafficking, and function. Understanding all the above is essential for a complete picture of the role of Kv channels in physiology and disease.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
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3
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Olah VJ, Goettemoeller AM, Rayaprolu S, Dammer EB, Seyfried NT, Rangaraju S, Dimidschstein J, Rowan MJM. Biophysical Kv3 channel alterations dampen excitability of cortical PV interneurons and contribute to network hyperexcitability in early Alzheimer's. eLife 2022; 11:75316. [PMID: 35727131 PMCID: PMC9278953 DOI: 10.7554/elife.75316] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 05/19/2022] [Indexed: 11/13/2022] Open
Abstract
In Alzheimer’s disease (AD), a multitude of genetic risk factors and early biomarkers are known. Nevertheless, the causal factors responsible for initiating cognitive decline in AD remain controversial. Toxic plaques and tangles correlate with progressive neuropathology, yet disruptions in circuit activity emerge before their deposition in AD models and patients. Parvalbumin (PV) interneurons are potential candidates for dysregulating cortical excitability as they display altered action potential (AP) firing before neighboring excitatory neurons in prodromal AD. Here, we report a novel mechanism responsible for PV hypoexcitability in young adult familial AD mice. We found that biophysical modulation of Kv3 channels, but not changes in their mRNA or protein expression, were responsible for dampened excitability in young 5xFAD mice. These K+ conductances could efficiently regulate near-threshold AP firing, resulting in gamma-frequency-specific network hyperexcitability. Thus, biophysical ion channel alterations alone may reshape cortical network activity prior to changes in their expression levels. Our findings demonstrate an opportunity to design a novel class of targeted therapies to ameliorate cortical circuit hyperexcitability in early AD.
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Affiliation(s)
- Viktor J Olah
- Department of Cell Biology, Emory University, Atlanta, United States
| | | | - Sruti Rayaprolu
- Department of Neurology, Emory University, Atlanta, United States
| | - Eric B Dammer
- Department of Biochemistry, Emory University, Atlanta, United States
| | | | | | | | - Matthew J M Rowan
- Department of Cell Biology, Emory University, Atlanta, United States
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4
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Spiers JG, Steinert JR. Nitrergic modulation of ion channel function in regulating neuronal excitability. Channels (Austin) 2021; 15:666-679. [PMID: 34802368 PMCID: PMC8632290 DOI: 10.1080/19336950.2021.2002594] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Nitric oxide (NO) signaling in the brain provides a wide range of functional properties in response to neuronal activity. NO exerts its effects through different signaling pathways, namely, through the canonical soluble guanylyl cyclase-mediated cGMP production route and via post-translational protein modifications. The latter pathways comprise cysteine S-nitrosylation and 3-nitrotyrosination of distinct tyrosine residues. Many ion channels are targeted by one or more of these signaling routes, which leads to their functional regulation under physiological conditions or facilities their dysfunction leading to channelopathies in many pathologies. The resulting alterations in ion channel function changes neuronal excitability, synaptic transmission, and action potential propagation. Transient and activity-dependent NO production mediates reversible ion channel modifications via cGMP and S-nitrosylation signaling, whereas more pronounced and longer-term NO production during conditions of elevated oxidative stress leads to increasingly cumulative and irreversible protein 3-nitrotyrosination. The complexity of this regulation and vast variety of target ion channels and their associated functional alterations presents a challenging task in assessing and understanding the role of NO signaling in physiology and disease.
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Affiliation(s)
- Jereme G Spiers
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
| | - Joern R Steinert
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK
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5
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Scheiblich H, Steinert JR. Nitrergic modulation of neuronal excitability in the mouse hippocampus is mediated via regulation of Kv2 and voltage-gated sodium channels. Hippocampus 2021; 31:1020-1038. [PMID: 34047430 DOI: 10.1002/hipo.23366] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/10/2021] [Accepted: 05/19/2021] [Indexed: 12/21/2022]
Abstract
Regulation of neuronal activity is a necessity for communication and information transmission. Many regulatory processes which have been studied provide a complex picture of how neurons can respond to permanently changing functional requirements. One such activity-dependent mechanism involves signaling mediated by nitric oxide (NO). Within the brain, NO is generated in response to neuronal NO synthase (nNOS) activation but NO-dependent pathways regulating neuronal excitability in the hippocampus remain to be fully elucidated. This study was set out to systematically assess the effects of NO on ion channel activities and intrinsic excitabilities of pyramidal neurons within the CA1 region of the mouse hippocampus. We characterized whole-cell potassium and sodium currents, both involved in action potential (AP) shaping and propagation and determined NO-mediated changes in excitabilities and AP waveforms. Our data describe a novel signaling by which NO, in a cGMP-independent manner, suppresses voltage-gated Kv2 potassium and voltage-gated sodium channel activities, thereby widening AP waveforms and reducing depolarization-induced AP firing rates. Our data show that glutathione, which possesses denitrosylating activity, is sufficient to prevent the observed nitrergic effects on potassium and sodium channels, whereas inhibition of cGMP signaling is also sufficient to abolish NO modulation of sodium currents. We propose that NO suppresses both ion channel activities via redox signaling and that an additional cGMP-mediated component is required to exert effects on sodium currents. Both mechanisms result in a dampened excitability and firing ability providing new data on nitrergic activities in the context of activity-dependent regulation of neuronal function following nNOS activation.
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Affiliation(s)
- Hannah Scheiblich
- Department of Neurodegenerative Disease and Geriatric Psychiatry/Neurology, University of Bonn Medical Center, Bonn, Germany
| | - Joern R Steinert
- Faculty of Medicine and Health Sciences, University of Nottingham, School of Life Sciences, Queen's Medical Centre, Nottingham, UK
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6
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Choudhury N, Linley D, Richardson A, Anderson M, Robinson SW, Marra V, Ciampani V, Walter SM, Kopp‐Scheinpflug C, Steinert JR, Forsythe ID. Kv3.1 and Kv3.3 subunits differentially contribute to Kv3 channels and action potential repolarization in principal neurons of the auditory brainstem. J Physiol 2020; 598:2199-2222. [DOI: 10.1113/jp279668] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 03/25/2020] [Indexed: 12/13/2022] Open
Affiliation(s)
- Nasreen Choudhury
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Deborah Linley
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Amy Richardson
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Michelle Anderson
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Susan W. Robinson
- Neurotoxicity at the Synaptic Interface MRC Toxicology Unit University of Leicester, UK
| | - Vincenzo Marra
- Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Victoria Ciampani
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Sophie M. Walter
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Conny Kopp‐Scheinpflug
- Division of Neurobiology Department Biology II Ludwig‐Maximilians‐University Munich Großhaderner Strasse 2 Planegg‐Martinsried D‐82152 Germany
| | - Joern R. Steinert
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
| | - Ian D. Forsythe
- Auditory Neurophysiology Laboratory, Department of Neuroscience Psychology & Behaviour College of Life Sciences University of Leicester Leicester LE1 7RH UK
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7
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Ciccone R, Piccialli I, Grieco P, Merlino F, Annunziato L, Pannaccione A. Synthesis and Pharmacological Evaluation of a Novel Peptide Based on Anemonia sulcata BDS-I Toxin as a New K V3.4 Inhibitor Exerting a Neuroprotective Effect Against Amyloid-β Peptide. Front Chem 2019; 7:479. [PMID: 31338361 PMCID: PMC6629785 DOI: 10.3389/fchem.2019.00479] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 06/21/2019] [Indexed: 12/28/2022] Open
Abstract
There is increasing evidence that the fast-inactivating potassium current IA, encoded by KV3. 4 channels, plays an important role in Alzheimer's Disease (AD), since the neurotoxic β-amyloid peptide1-42 (Aβ1-42) increases the IA current triggering apoptotic processes. The specific inhibition of KV3.4 by the marine toxin extracted from Anemonia sulcata, named blood depressing substance-I (BDS-I), reverts the Aβ peptide-induced cell death. The aim of the present study was to identify the smallest fragments of BDS-I, obtained by peptide synthesis, able to inhibit KV3.4 currents. For this purpose, whole-cell patch clamp technique was used to evaluate the effects of BDS-I fragments on KV3.4 currents in CHO cells heterologously expressing KV3.4. We found that BDS-I[1-8] fragment, containing the N-terminal octapeptide sequence of full length BDS-I, was able to inhibit KV3.4 currents in a concentration dependent manner, whereas the scrambled sequence of BDS-I[1-8] and all the other fragments obtained from BDS-I full length were ineffective. As we demonstrated in a previous study, BDS-I full length is able to counteract Aβ1-42-induced enhancement of KV3.4 activity, preventing Aβ1-42-induced caspase-3 activation and the abnormal nuclear morphology in NGF-differentiated PC-12 cells. Similarly to BDS-I, we found that BDS-I[1-8] blocking KV3.4 currents prevented Aβ1-42-induced caspase-3 activation and apoptotic processes. Collectively, these results suggest that BDS-I[1-8] could represent a lead compound to be developed as a new drug targeting KV3.4 channels.
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Affiliation(s)
- Roselia Ciccone
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, Federico II University of Naples, Naples, Italy
| | - Ilaria Piccialli
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, Federico II University of Naples, Naples, Italy
| | - Paolo Grieco
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Francesco Merlino
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | | | - Anna Pannaccione
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, Federico II University of Naples, Naples, Italy
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8
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Kaczmarek LK, Zhang Y. Kv3 Channels: Enablers of Rapid Firing, Neurotransmitter Release, and Neuronal Endurance. Physiol Rev 2017; 97:1431-1468. [PMID: 28904001 PMCID: PMC6151494 DOI: 10.1152/physrev.00002.2017] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/24/2017] [Accepted: 05/05/2017] [Indexed: 12/11/2022] Open
Abstract
The intrinsic electrical characteristics of different types of neurons are shaped by the K+ channels they express. From among the more than 70 different K+ channel genes expressed in neurons, Kv3 family voltage-dependent K+ channels are uniquely associated with the ability of certain neurons to fire action potentials and to release neurotransmitter at high rates of up to 1,000 Hz. In general, the four Kv3 channels Kv3.1-Kv3.4 share the property of activating and deactivating rapidly at potentials more positive than other channels. Each Kv3 channel gene can generate multiple protein isoforms, which contribute to the high-frequency firing of neurons such as auditory brain stem neurons, fast-spiking GABAergic interneurons, and Purkinje cells of the cerebellum, and to regulation of neurotransmitter release at the terminals of many neurons. The different Kv3 channels have unique expression patterns and biophysical properties and are regulated in different ways by protein kinases. In this review, we cover the function, localization, and modulation of Kv3 channels and describe how levels and properties of the channels are altered by changes in ongoing neuronal activity. We also cover how the protein-protein interaction of these channels with other proteins affects neuronal functions, and how mutations or abnormal regulation of Kv3 channels are associated with neurological disorders such as ataxias, epilepsies, schizophrenia, and Alzheimer's disease.
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Affiliation(s)
- Leonard K Kaczmarek
- Departments of Pharmacology and of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | - Yalan Zhang
- Departments of Pharmacology and of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
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9
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Yamazaki Y, Hozumi Y, Kaneko K, Fujii S. Modulatory Effects of Perineuronal Oligodendrocytes on Neuronal Activity in the Rat Hippocampus. Neurochem Res 2017; 43:27-40. [PMID: 28444636 DOI: 10.1007/s11064-017-2278-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 04/17/2017] [Accepted: 04/20/2017] [Indexed: 12/31/2022]
Abstract
Action potentials are fundamental to relaying information from region to region in the nervous system. Changes in action potential firing patterns in neural circuits influence how the brain processes information. In our previous study, we focused on interneuron/perineuronal astrocyte pairs in the hippocampal CA1 region and reported that direct depolarization of perineuronal astrocytes modulated the firing pattern of interneurons. In the current study, we investigated the morphological and electrophysiological properties of perineuronal oligodendrocytes, and examined their modulatory effects on interneuronal firing in the CA1 region. Perineuronal oligodendrocytes only had a few processes, which were crooked, intricately twisted, and twined around the soma and proximal region of the main processes of adjacent interneurons. Whole-cell current patterns of perineuronal oligodendrocytes were homogenous and the current-voltage relationship showed remarkable outward rectification. Although the K+ channel blockers, tetraethylammonium and 4-aminopyridine, clearly blocked outward currents, Ba2+ did not significantly alter whole-cell currents. Unlike perineuronal astrocytes, the depolarization of perineuronal oligodendrocytes had no effect on interneuronal firing; however, when the interneurons were firing at a higher frequency, the hyperpolarization of perineuronal oligodendrocytes suppressed their action potentials. The suppressive effects of perineuronal oligodendrocytes were inhibited in the presence of a low concentration of tetraethylammonium, which selectively blocked deep and fast afterhyperpolarization. These results suggest that perineuronal oligodendrocytes suppress interneuronal firing through their influence on K+ channels, which are responsible for deep and fast afterhyperpolarization.
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Affiliation(s)
- Yoshihiko Yamazaki
- Department of Physiology, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata, 990-9585, Japan.
| | - Yasukazu Hozumi
- Department of Anatomy & Cell Biology, Yamagata University School of Medicine, Yamagata, 990-9585, Japan.,Department of Cell Biology and Morphology, Akita University Graduate School of Medicine, Akita, 010-8543, Japan
| | - Kenya Kaneko
- Department of Physiology, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata, 990-9585, Japan
| | - Satoshi Fujii
- Department of Physiology, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata, 990-9585, Japan
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10
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Parodi J, Montecinos-Oliva C, Varas R, Alfaro IE, Serrano FG, Varas-Godoy M, Muñoz FJ, Cerpa W, Godoy JA, Inestrosa NC. Wnt5a inhibits K(+) currents in hippocampal synapses through nitric oxide production. Mol Cell Neurosci 2015; 68:314-22. [PMID: 26311509 DOI: 10.1016/j.mcn.2015.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 06/05/2015] [Accepted: 08/19/2015] [Indexed: 02/06/2023] Open
Abstract
Hippocampal synapses play a key role in memory and learning processes by inducing long-term potentiation and depression. Wnt signaling is essential in the development and maintenance of synapses via several mechanisms. We have previously found that Wnt5a induces the production of nitric oxide (NO), which modulates NMDA receptor expression in the postsynaptic regions of hippocampal neurons. Here, we report that Wnt5a selectively inhibits a voltage-gated K(+) current (Kv current) and increases synaptic activity in hippocampal slices. Further supporting a specific role for Wnt5a, the soluble Frizzled receptor protein (sFRP-2; a functional Wnt antagonist) fully inhibits the effects of Wnt5a. We additionally show that these responses to Wnt5a are mediated by activation of a ROR2 receptor and increased NO production because they are suppressed by the shRNA-mediated knockdown of ROR2 and by 7-nitroindazole, a specific inhibitor of neuronal NOS. Together, our results show that Wnt5a increases NO production by acting on ROR2 receptors, which in turn inhibit Kv currents. These results reveal a novel mechanism by which Wnt5a may regulate the excitability of hippocampal neurons.
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Affiliation(s)
- Jorge Parodi
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carla Montecinos-Oliva
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rodrigo Varas
- Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Talca, Chile
| | - Iván E Alfaro
- Fundación Ciencia y Vida, Santiago, Chile; Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Valparaiso, Chile
| | - Felipe G Serrano
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - Francisco J Muñoz
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Parc de Recerca Biomédica de Barcelonab, Spain
| | - Waldo Cerpa
- Laboratorio de Función y Patología Neuronal, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | - Juan A Godoy
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Parc de Recerca Biomédica de Barcelonab, Spain
| | - Nibaldo C Inestrosa
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, Australia; Centro UC Síndrome de Down, Pontificia Universidad Católica de Chile, Santiago, Chile; Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile.
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11
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Tricoire L, Vitalis T. Neuronal nitric oxide synthase expressing neurons: a journey from birth to neuronal circuits. Front Neural Circuits 2012; 6:82. [PMID: 23227003 PMCID: PMC3514612 DOI: 10.3389/fncir.2012.00082] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 10/25/2012] [Indexed: 12/17/2022] Open
Abstract
Nitric oxide (NO) is an important signaling molecule crucial for many physiological processes such as synaptic plasticity, vasomotricity, and inflammation. Neuronal nitric oxide synthase (nNOS) is the enzyme responsible for the synthesis of NO by neurons. In the juvenile and mature hippocampus and neocortex nNOS is primarily expressed by subpopulations of GABAergic interneurons. Over the past two decades, many advances have been achieved in the characterization of neocortical and hippocampal nNOS expressing neurons. In this review, we summarize past and present studies that have characterized the electrophysiological, morphological, molecular, and synaptic properties of these neurons. We also discuss recent studies that have shed light on the developmental origins and specification of GABAergic neurons with specific attention to neocortical and hippocampal nNOS expressing GABAergic neurons. Finally, we summarize the roles of NO and nNOS-expressing inhibitory neurons.
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Affiliation(s)
- Ludovic Tricoire
- CNRS-UMR 7102, Laboratoire de Neurobiologie des Processus Adaptatifs, Université Pierre et Marie Curie Paris, France
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12
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Steinert JR, Robinson SW, Tong H, Haustein MD, Kopp-Scheinpflug C, Forsythe ID. Nitric oxide is an activity-dependent regulator of target neuron intrinsic excitability. Neuron 2011; 71:291-305. [PMID: 21791288 PMCID: PMC3245892 DOI: 10.1016/j.neuron.2011.05.037] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2011] [Indexed: 02/07/2023]
Abstract
Activity-dependent changes in synaptic strength are well established as mediating long-term plasticity underlying learning and memory, but modulation of target neuron excitability could complement changes in synaptic strength and regulate network activity. It is thought that homeostatic mechanisms match intrinsic excitability to the incoming synaptic drive, but evidence for involvement of voltage-gated conductances is sparse. Here, we show that glutamatergic synaptic activity modulates target neuron excitability and switches the basis of action potential repolarization from Kv3 to Kv2 potassium channel dominance, thereby adjusting neuronal signaling between low and high activity states, respectively. This nitric oxide-mediated signaling dramatically increases Kv2 currents in both the auditory brain stem and hippocampus (>3-fold) transforming synaptic integration and information transmission but with only modest changes in action potential waveform. We conclude that nitric oxide is a homeostatic regulator, tuning neuronal excitability to the recent history of excitatory synaptic inputs over intervals of minutes to hours.
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Affiliation(s)
- Joern R Steinert
- Neurotoxicity at the Synaptic Interface, MRC Toxicology Unit, Hodgkin Building, University of Leicester, Leicester LE1 9HN, UK
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13
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Steinert JR, Chernova T, Forsythe ID. Nitric oxide signaling in brain function, dysfunction, and dementia. Neuroscientist 2011; 16:435-52. [PMID: 20817920 DOI: 10.1177/1073858410366481] [Citation(s) in RCA: 315] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Nitric oxide (NO) is an important signaling molecule that is widely used in the nervous system. With recognition of its roles in synaptic plasticity (long-term potentiation, LTP; long-term depression, LTD) and elucidation of calcium-dependent, NMDAR-mediated activation of neuronal nitric oxide synthase (nNOS), numerous molecular and pharmacological tools have been used to explore the physiology and pathological consequences for nitrergic signaling. In this review, the authors summarize the current understanding of this subtle signaling pathway, discuss the evidence for nitrergic modulation of ion channels and homeostatic modulation of intrinsic excitability, and speculate about the pathological consequences of spillover between different nitrergic compartments in contributing to aberrant signaling in neurodegenerative disorders. Accumulating evidence points to various ion channels and particularly voltage-gated potassium channels as signaling targets, whereby NO mediates activity-dependent control of intrinsic neuronal excitability; such changes could underlie broader mechanisms of synaptic plasticity across neuronal networks. In addition, the inability to constrain NO diffusion suggests that spillover from endothelium (eNOS) and/or immune compartments (iNOS) into the nervous system provides potential pathological sources of NO and where control failure in these other systems could have broader neurological implications. Abnormal NO signaling could therefore contribute to a variety of neurodegenerative pathologies such as stroke/excitotoxicity, Alzheimer's disease, multiple sclerosis, and Parkinson's disease.
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Affiliation(s)
- Joern R Steinert
- Neurotoxicity at the Synaptic Interface, MRC Toxicology Unit, University of Leicester, Leicester, UK
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14
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Bagdy G, Riba P, Kecskeméti V, Chase D, Juhász G. Headache-type adverse effects of NO donors: vasodilation and beyond. Br J Pharmacol 2010; 160:20-35. [PMID: 20331608 DOI: 10.1111/j.1476-5381.2010.00643.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Although nitrate therapy, used in the treatment of cardiovascular disorders, is frequently associated with side-effects, mainly headaches, the summaries of product characteristics of nitrate-containing medicines do not report detailed description of headaches and even do not highlight the possibility of nitrate-induced migraine. Two different types of nitrate-induced headaches have been described: (i) immediate headaches that develop within the first hour of the application, are mild or medium severity without characteristic symptoms for migraine, and ease spontaneously; and (ii) delayed, moderate or severe migraine-type headaches (occurring mainly in subjects with personal or family history of migraine), that develop 3-6 h after the intake of nitrates, with debilitating, long-lasting symptoms including nausea, vomiting, photo- and/or phono-phobia. These two types of headaches are remarkably different, not only in their timing and symptoms, but also in the persons who are at risk. Recent studies provide evidence that the two headache types are caused by different mechanisms: immediate headaches are connected to vasodilation caused by nitric oxide (NO) release, while migraines are triggered by other actions such as the release of calcitonin gene-related peptide or glutamate, or changes in ion channel function mediated by cyclic guanosine monophosphate or S-nitrosylation. Migraines usually need anti-attack medication, such as triptans, but these drugs are contraindicated in most medical conditions that are treated using nitrates. In conclusion, these data recommend the correction of summaries of nitrate product characteristics, and also suggest a need to develop new types of anti-migraine drugs, effective in migraine attacks, that could be used in patients with risk for angina pectoris.
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Affiliation(s)
- G Bagdy
- Department of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary.
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15
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Steinert JR, Kopp-Scheinpflug C, Baker C, Challiss RAJ, Mistry R, Haustein MD, Griffin SJ, Tong H, Graham BP, Forsythe ID. Nitric oxide is a volume transmitter regulating postsynaptic excitability at a glutamatergic synapse. Neuron 2009; 60:642-56. [PMID: 19038221 DOI: 10.1016/j.neuron.2008.08.025] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Revised: 08/26/2008] [Accepted: 08/29/2008] [Indexed: 01/14/2023]
Abstract
Neuronal nitric oxide synthase (nNOS) is broadly expressed in the brain and associated with synaptic plasticity through NMDAR-mediated calcium influx. However, its physiological activation and the mechanisms by which nitric oxide (NO) influences synaptic transmission have proved elusive. Here, we exploit the unique input-specificity of the calyx of Held to characterize NO modulation at this glutamatergic synapse in the auditory pathway. NO is generated in an activity-dependent manner by MNTB principal neurons receiving a calyceal synaptic input. It acts in the target neuron and adjacent inactive neurons to modulate excitability and synaptic efficacy, inhibiting postsynaptic Kv3 potassium currents (via phosphorylation), reducing EPSCs and so increasing action potential duration and reducing transmission fidelity. We conclude that NO serves as a volume transmitter and slow dynamic modulator, integrating spontaneous and evoked neuronal firing, thereby providing an index of global activity and regulating information transmission across a population of active and inactive neurons.
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Affiliation(s)
- Joern R Steinert
- MRC Toxicology Unit, Hodgkin Building, University of Leicester, Leicester LE1 9HN, UK
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16
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Abstract
As a chemical transmitter in the mammalian central nervous system, nitric oxide (NO) is still thought a bit of an oddity, yet this role extends back to the beginnings of the evolution of the nervous system, predating many of the more familiar neurotransmitters. During the 20 years since it became known, evidence has accumulated for NO subserving an increasing number of functions in the mammalian central nervous system, as anticipated from the wide distribution of its synthetic and signal transduction machinery within it. This review attempts to probe beneath those functions and consider the cellular and molecular mechanisms through which NO evokes short- and long-term modifications in neural performance. With any transmitter, understanding its receptors is vital for decoding the language of communication. The receptor proteins specialised to detect NO are coupled to cGMP formation and provide an astonishing degree of amplification of even brief, low amplitude NO signals. Emphasis is given to the diverse ways in which NO receptor activation initiates changes in neuronal excitability and synaptic strength by acting at pre- and/or postsynaptic locations. Signalling to non-neuronal cells and an unexpected line of communication between endothelial cells and brain cells are also covered. Viewed from a mechanistic perspective, NO conforms to many of the rules governing more conventional neurotransmission, particularly of the metabotropic type, but stands out as being more economical and versatile, attributes that presumably account for its spectacular evolutionary success.
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Affiliation(s)
- John Garthwaite
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WCIE 6BT, UK.
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17
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Chen L, Liu C, Liu L. The modulation of voltage-gated potassium channels by anisotonicity in trigeminal ganglion neurons. Neuroscience 2008; 154:482-95. [PMID: 18456412 DOI: 10.1016/j.neuroscience.2008.03.046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 03/12/2008] [Accepted: 03/19/2008] [Indexed: 12/20/2022]
Abstract
Voltage-gated potassium channels (VGPCs) play an important role in many physiological functions by controlling the electrical properties and excitability of cells. Changes in tonicity in the peripheral nervous system can activate nociceptors and produce pain. Here, using whole cell patch clamp techniques, we explore how hypo- and hypertonicity modulate VGPCs in cultured rat and mouse trigeminal ganglion (TG) neurons. We found that hypo- and hypertonicity had different effects on slow-inactivating K+ current (IK) and fast-inactivating K+ current (IA): hypotonicity increased IK but had no effect on IA while hypertonicity depressed both IK and IA. The increase of IK by hypotonicity was mimicked by transient receptor potential vanilloid 4 (TRPV4) receptor activator 4alpha-phorbol-12,13-didecanoate (4alpha-PDD) but hypotonicity did not exhibit increase in TRPV4-/- mice TG neurons, suggesting that TRPV4 receptor was involved in hypotonicity-induced response. We also found that inactivation of PKC selectively reversed the increase of IK by hypotonicity, whereas antagonism of G-protein selectively rescued the inhibitions of IK and IA by hypertonicity, indicating that different intracellular signaling pathways were required for the modulation by hypo- and hypertonicity. In summary, changes in osmolality have various effects on IK and IA and different receptors and second messenger systems are selective for the modulation of VGPCs induced by hypo- versus hypertonicity.
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Affiliation(s)
- L Chen
- Department of Physiology, Tongji Medical College, Huazhong University of Science and Technology, No 13, Hangkong Road, Wuhan, PR China
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18
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Yang Q, Chen SR, Li DP, Pan HL. Kv1.1/1.2 channels are downstream effectors of nitric oxide on synaptic GABA release to preautonomic neurons in the paraventricular nucleus. Neuroscience 2007; 149:315-27. [PMID: 17869444 DOI: 10.1016/j.neuroscience.2007.08.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Revised: 07/27/2007] [Accepted: 08/03/2007] [Indexed: 01/20/2023]
Abstract
The paraventricular nucleus (PVN) of the hypothalamus is important for the neural regulation of cardiovascular function. Nitric oxide (NO) increases synaptic GABA release to presympathetic PVN neurons through the cyclic guanosine monophosphate (cGMP)/protein kinase G signaling pathway. However, the downstream signaling mechanisms underlying the effect of NO on synaptic GABA release remain unclear. In this study, whole-cell voltage-clamp recordings were performed on retrograde-labeled spinally projecting PVN neurons in rat brain slices. Bath application of the NO precursor l-arginine or the NO donor S-nitroso-N-acetylpenicillamine (SNAP) significantly increased the frequency of GABAergic miniature inhibitory postsynaptic currents (mIPSCs) in labeled PVN neurons. A specific antagonist of cyclic ADP ribose, 8-bromo-cyclic ADP ribose (8-Br-cADPR), had no significant effect on l-arginine-induced potentiation of mIPSCs. Surprisingly, blocking of voltage-gated potassium channels (Kv) with 4-aminopyridine or alpha-dendrotoxin eliminated the effect of l-arginine on mIPSCs in all labeled PVN neurons tested. The membrane permeable cGMP analog mimicked the effect of l-arginine on mIPSCs, and this effect was blocked by alpha-dendrotoxin. Furthermore, the specific Kv channel blocker for Kv1.1 (dendrotoxin-K) or Kv1.2 (tityustoxin-Kalpha) abolished the effect of l-arginine on mIPSCs in all neurons tested. SNAP failed to inhibit the firing activity of labeled PVN neurons in the presence of dendrotoxin-K, Kalpha. Additionally, the immunoreactivity of Kv1.1 and Kv1.2 subunits was colocalized extensively with synaptophysin in the PVN. These findings suggest that NO increases GABAergic input to PVN presympathetic neurons through a downstream mechanism involving the Kv1.1 and Kv1.2 channels at the nerve terminals.
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Affiliation(s)
- Q Yang
- Department of Anesthesiology and Pain Medicine, Unit 110, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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19
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Yang M, Kahn AM. Insulin-inhibited and stimulated cultured vascular smooth muscle cell migration are related to divergent effects on protein phosphatase-2A and autonomous calcium/calmodulin-dependent protein kinase II. Atherosclerosis 2007; 196:227-233. [PMID: 17553505 DOI: 10.1016/j.atherosclerosis.2007.04.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 03/30/2007] [Accepted: 04/30/2007] [Indexed: 11/26/2022]
Abstract
Insulin, in the permissive presence of nitric oxide (NO), stimulates cGMP production which inhibits autonomous calcium/calmodulin-dependent protein kinase II (CaM kinase II) thereby inhibiting cultured vascular smooth muscle cell (VSMC) migration. In the presence of angiotensin II (Ang II), insulin stimulates NAD(P)H oxidase activity leading to increased VSMC migration. We wished to see whether insulin-stimulated cGMP stimulates protein phosphatase-2A (PP-2A) thereby inhibiting autonomous CaM kinase II and migration, and whether insulin, in the presence of Ang II, inhibits PP-2A and stimulates autonomous CaM kinase II in a NAD(P)H oxidase-dependent manner. One nanomole per litre of insulin in the presence of NO, or 50 micromol/L 8-Br-cGMP stimulated PP-2A activity by 46+/-6 and 247+/-23%, respectively (both P<0.05), and 8-Br-cGMP inhibited autonomous CaM kinase II activity by 67+/-9% (P<0.05) by a 10 nmol/L okadaic acid-sensitive pathway. Insulin plus Ang II inhibited PP-2A activity by 57+/-7% (P<0.05) and stimulated autonomous CaM kinase II activity by 120+/-14% (P<0.05), both by an apocynin-sensitive pathway. 8-Br-cGMP-inhibited VSMC migration was blocked by okadaic acid. It is concluded that insulin in the presence of NO stimulates cGMP which stimulates PP-2A activity causing inhibition of autonomous CaM kinase II activity and thus VSMC migration, and that insulin in the presence of Ang II inhibits PP-2A and stimulates autonomous CaM kinase II activities by a NAD(P)H oxidase-dependent mechanism which are associated with insulin-stimulated NAD(P)H oxidase-dependent migration.
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Affiliation(s)
- Ming Yang
- Division of Nephrology and Hypertension, Department of Medicine, Medical School, University of Texas Health Science Center, Houston, United States
| | - Andrew M Kahn
- Division of Nephrology and Hypertension, Department of Medicine, Medical School, University of Texas Health Science Center, Houston, United States.
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20
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Yeung SYM, Thompson D, Wang Z, Fedida D, Robertson B. Modulation of Kv3 subfamily potassium currents by the sea anemone toxin BDS: significance for CNS and biophysical studies. J Neurosci 2006; 25:8735-45. [PMID: 16177043 PMCID: PMC1314979 DOI: 10.1523/jneurosci.2119-05.2005] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Kv3 potassium channels, with their ultra-rapid gating and high activation threshold, are essential for high-frequency firing in many CNS neurons. Significantly, the Kv3.4 subunit has been implicated in the major CNS disorders Parkinson's and Alzheimer's diseases, and it is claimed that selectively targeting this subunit will have therapeutic utility. Previous work suggested that BDS toxins ("blood depressing substance," from the sea anemone Anemonia sulcata) were specific blockers for rapidly inactivating Kv3.4 channels, and consequently these toxins are increasingly used as diagnostic agents for Kv3.4 subunits in central neurons. However, precisely how selective are these toxins for this important CNS protein? We show that BDS is not selective for Kv3.4 but markedly inhibits current through Kv3.1 and Kv3.2 channels. Inhibition comes about not by "pore block" but by striking modification of Kv3 gating kinetics and voltage dependence. Activation and inactivation kinetics are slowed by BDS-I and BDS-II, and V(1/2) for activation is shifted to more positive voltages. Alanine substitution mutagenesis around the S3b and S4 segments of Kv3.2 reveals that BDS acts via voltage-sensing domains, and, consistent with this, ON gating currents from nonconducting Kv3.2 are markedly inhibited. The altered kinetics and gating properties, combined with lack of subunit selectivity with Kv3 subunits, seriously affects the usefulness of BDS toxins in CNS studies. Furthermore, our results do not easily fit with the voltage sensor "paddle" structure proposed recently for Kv channels. Our data will be informative for experiments designed to dissect out the roles of Kv3 subunits in CNS function and dysfunction.
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Affiliation(s)
- Shuk Yin M Yeung
- Neuroscience Group, School of Biomedical Sciences, University of Leeds, Leeds LS2 9NQ, United Kingdom
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21
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Secondo A, Pannaccione A, Cataldi M, Sirabella R, Formisano L, Di Renzo G, Annunziato L. Nitric oxide induces [Ca2+]i oscillations in pituitary GH3 cells: involvement of IDR and ERG K+ currents. Am J Physiol Cell Physiol 2005; 290:C233-43. [PMID: 16207796 DOI: 10.1152/ajpcell.00231.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of nitric oxide (NO) in the occurrence of intracellular Ca2+ concentration ([Ca2+]i) oscillations in pituitary GH3 cells was evaluated by studying the effect of increasing or decreasing endogenous NO synthesis with L-arginine and nitro-L-arginine methyl ester (L-NAME), respectively. When NO synthesis was blocked with L-NAME (1 mM) [Ca2+]i, oscillations disappeared in 68% of spontaneously active cells, whereas 41% of the quiescent cells showed [Ca2+]i oscillations in response to the NO synthase (NOS) substrate L-arginine (10 mM). This effect was reproduced by the NO donors NOC-18 and S-nitroso-N-acetylpenicillamine (SNAP). NOC-18 was ineffective in the presence of the L-type voltage-dependent Ca2+ channels (VDCC) blocker nimodipine (1 microM) or in Ca2+-free medium. Conversely, its effect was preserved when Ca2+ release from intracellular Ca2+ stores was inhibited either with the ryanodine-receptor blocker ryanodine (500 microM) or with the inositol 1,4,5-trisphosphate receptor blocker xestospongin C (3 microM). These results suggest that NO induces the appearance of [Ca2+]i oscillations by determining Ca2+ influx. Patch-clamp experiments excluded that NO acted directly on VDCC but suggested that NO determined membrane depolarization because of the inhibition of voltage-gated K+ channels. NOC-18 and SNAP caused a decrease in the amplitude of slow-inactivating (IDR) and ether-à-go-go-related gene (ERG) hyperpolarization-evoked, deactivating K+ currents. Similar results were obtained when GH3 cells were treated with L-arginine. The present study suggests that in GH3 cells, endogenous NO plays a permissive role for the occurrence of spontaneous [Ca2+]i oscillations through an inhibitory effect on IDR and on IERG.
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Affiliation(s)
- Agnese Secondo
- Division of Pharmacology, Dept. of Neuroscience, School of Medicine, Federico II Univ. of Naples, via Sergio Pansini 5, 80131 Naples, Italy
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22
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Fernandez FR, Mehaffey WH, Molineux ML, Turner RW. High-threshold K+ current increases gain by offsetting a frequency-dependent increase in low-threshold K+ current. J Neurosci 2005; 25:363-71. [PMID: 15647479 PMCID: PMC6725476 DOI: 10.1523/jneurosci.3950-04.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
High-frequency firing neurons are found in numerous central systems, including the auditory brainstem, thalamus, hippocampus, and neocortex. The kinetics of high-threshold K+ currents (IK(HT)) from the Kv3 subfamily has led to the proposal that these channels offset cumulative Na+ current inactivation and stabilize tonic high-frequency firing. However, all high-frequency firing neurons, examined to date, also express low-threshold K+ currents (IK(LT)) that have slower kinetics and play an important role in setting the subthreshold and filtering properties of the neuron. IK(LT) has also been shown to dampen excitability and is therefore likely to oppose high-frequency firing. In this study, we examined the role of IK(HT) in pyramidal cells of the electrosensory lobe of weakly electric fish, which are characterized by high-frequency firing, a very wide frequency range, and high levels of IK(HT). In particular, we examined the mechanisms that allow IK(HT) to set the gain of the F-I relationship by interacting with another low-threshold K+ current. We found that IK(HT) increases the gain of the F-I relationship and influences spike waveform almost exclusively in the high-frequency firing range. The frequency dependence arises from IK(HT) influencing both the IK(LT) and Na+ currents. IK(HT) thus plays a significant role in stabilizing high-frequency firing by preventing a steady-state accumulation of IK(LT) that is as important as preventing Na+ current inactivation.
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Affiliation(s)
- Fernando R Fernandez
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
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23
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Sokolovski S, Hills A, Gay R, Garcia-Mata C, Lamattina L, Blatt MR. Protein phosphorylation is a prerequisite for intracellular Ca2+ release and ion channel control by nitric oxide and abscisic acid in guard cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2005; 43:520-9. [PMID: 16098106 DOI: 10.1111/j.1365-313x.2005.02471.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Recent work has indicated that nitric oxide (NO) and its synthesis are important elements of signal cascades in plant-pathogen defence, and are a prerequisite for drought and abscisic acid (ABA) responses in Arabidopsis thaliana and Vicia faba guard cells. NO regulates inward-rectifying K+ channels and Cl- channels of Vicia guard cells via intracellular Ca2+ release. However, its integration with related signals, including the actions of serine-threonine protein kinases, is less well defined. We report here that the elevation of cytosolic-free [Ca2+] ([Ca2+]i) mediated by NO in guard cells is reversibly inhibited by the broad-range protein kinase antagonists staurosporine and K252A, but not by the tyrosine kinase antagonist genistein. The effects of kinase antagonism translate directly to a loss of NO-sensitivity of the inward-rectifying K+ channels and background (Cl- channel) current, and to a parallel loss in sensitivity of the K+ channels to ABA. These results demonstrate that NO-dependent signals can be modulated through protein phosphorylation upstream of intracellular Ca2+ release, and they implicate a target for protein kinase control in ABA signalling that feeds into NO-dependent Ca2+ release.
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Affiliation(s)
- Sergei Sokolovski
- Laboratory of Plant Physiology and Biophysics, Bower Building, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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24
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William M, Vien J, Hamilton E, Garcia A, Bundgaard H, Clarke RJ, Rasmussen HH. The nitric oxide donor sodium nitroprusside stimulates the Na+-K+ pump in isolated rabbit cardiac myocytes. J Physiol 2005; 565:815-25. [PMID: 15817632 PMCID: PMC1464570 DOI: 10.1113/jphysiol.2005.086447] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Nitric oxide (NO) affects the membrane Na(+)-K(+) pump in a tissue-dependent manner. Stimulation of intrinsic pump activity, stimulation secondary to NO-induced Na(+) influx into cells or inhibition has been reported. We used the whole-cell patch clamp technique to measure electrogenic Na(+)-K(+) pump current (I(p)) in rabbit ventricular myocytes. Myocytes were voltage clamped with wide-tipped patch pipettes to achieve optimal perfusion of the intracellular compartment, and I(p) was identified as the shift in holding current induced by 100 microm ouabain. The NO donor sodium nitroprusside (SNP) in concentrations of 1, 10, 50 or 100 microm induced a significant increase in I(p) when the intracellular compartment was perfused with pipette solutions containing 10 mm Na(+), a concentration near physiological levels. SNP had no effect when the pump was near-maximally activated by 80 mm Na(+) in pipette solutions. Stimulation persisted in the absence of extracellular Na(+), indicating its independence of transmembrane Na(+) influx. The SNP-induced pump stimulation was abolished by inhibition of soluble guanylyl cyclase (sGC) with 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one, by inhibition of protein kinase G (PKG) with KT-5823 or by inhibition of protein phosphatase with okadaic acid. Inclusion of the non-hydrolysable cGMP analogue 8pCPT-cGMP, activated recombinant PKG or the sGC-activator YC-1 in patch pipette filling solutions reproduced the SNP-induced pump stimulation. Pump stimulation induced by YC-1 was dependent on the Na(+) concentration but not the K(+) concentration in pipette filling solutions, suggesting an altered sensitivity of the Na(+)-K(+) pump to intracellular Na(+).
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Affiliation(s)
- Maged William
- Department of Cardiology, Royal North Shore Hospital, St Leonards, NSW 2065, Australia
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25
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Ngezahayo A, Altmann B, Kolb HA. Regulation of ion fluxes, cell volume and gap junctional coupling by cGMP in GFSHR-17 granulosa cells. J Membr Biol 2004; 194:165-76. [PMID: 14502429 DOI: 10.1007/s00232-003-2033-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2002] [Indexed: 01/24/2023]
Abstract
Gap junctional communication between granulosa cells seems to play a crucial role for follicular growth and atresia. Application of the double whole-cell patch-clamp- and ratiometric fura-2-techniques allowed a simultaneous measurement of gap junctional conductance ( G(j)) and cytoplasmic concentration of free Ca(2+) ([Ca(2+)](i)) in a rat granulosa cell line GFSHR-17. The voltage-dependent gating of G(j) varied for different cell pairs. One population exhibited a bell-shape dependence of G(j) on transjunctional voltage, which was strikingly similar to that of Cx43/Cx43 homotypic gap junction channels expressed in pairs of oocytes of Xenopus laevis. Within 15-20 min, gap junctional uncoupling occurred spontaneously, which was preceded by a sustained increase of [Ca(2+)](i) and accompanied by shrinkage of cellular volume. These responses to the whole-cell configuration were avoided by absence of extracellular Ca(2+), blockage of K(+) efflux, or addition of 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) to the pipette solution. Even in the absence of extracellular Ca(2+) or blockage of K(+) efflux, formation of whole-cell configuration generated a Ca(2+) spike that could be suppressed by the presence of 8-Br-cGMP. We propose that intracellular cGMP regulates Ca(2+) release from intracellular Ca(2+) stores, which activates sustained Ca(2+) influx, K(+) efflux and cellular shrinkage. We discuss whether gap junctional conductance is directly affected by cGMP or by cellular shrinkage and whether gap junctional coupling and/or cell shrinkage is involved in the regulation of apoptotic/necrotic processes in granulosa cells.
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Affiliation(s)
- A Ngezahayo
- Institut für Biophysik, Universität Hannover, Herrenhäuserstr. 2, D-30419 Hannover, Germany
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26
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Chen LW, Hwang YC, Chen CJ, Wang JS, Chen JS, Hsu CM. Burn-induced lung damage in rat is mediated by a nitric oxide/cGMP system. Shock 2004; 20:369-74. [PMID: 14501952 DOI: 10.1097/01.shk.0000086520.18735.df] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This study was conducted to demonstrate the burn-induced lung neutrophil deposition and damage in rats is affected by the nitric oxide (NO)-dependent downstream cGMP signaling. In experiment 1, 1H-[1,2,4] oxadiazolo [4,3-alpha] quinoxalin-1-one (ODQ) was given (20 mg/kg i.p.) to specific pathogen-free Sprague-Dawley rats immediately postburn to suppress the guanylate cyclase (GC) activity. At 8 h after burn, blood was assayed for the peroxynitrite-mediated dihydrorhodamine 123 (DHR 123) oxidation and lung tissues were harvested for myeloperoxidase (MPO) determination and histological studies. Pulmonary microvascular dysfunction was quantified by measuring the extravasations of Evans blue dye. In experiment 2, Sodium nitroprusside (SNP) was given (2 mM, i.p.) to elevate cGMP levels and ODQ (20 mg/kg, i.p.) or methylene blue (100 microM, i.p.) or saline was given. The animals were sacrificed 4 h after injection and lung tissues were harvested for iNOS mRNA study. The MPO activity in lung, blood DHR 123 oxidation level, and lung permeability increased up to 2-fold, 4-fold, and 2.5-fold after burn. Inhibition of GC by ODQ administration significantly decreased MPO activity, blood DHR 123 oxidation, and lung permeability by 55%, 66%, and 53%, respectively, and markedly decreased the thermal injury-induced perivascular and interstitial inflammatory cell infiltration and septum edema. The protective effects of ODQ were comparable to the use of selective iNOS inhibitor as demonstrated previously. Furthermore, ODQ decreased the burn or SNP-induced iNOS mRNA levels at 4 h after burn. These findings suggest that burn-induced lung dysfunction is mediated by the NO/cGMP system because it is abolished by application of either iNOS inhibitor or GC inhibitor. Also, the beneficial effect of ODQ is partly due to the attenuation of burn-induced iNOS expression by GC inhibition.
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Affiliation(s)
- Lee-Wei Chen
- Department of Surgery, Kaohsiung Veterans General Hospital, National Yang-Ming Medical University, Taipei, Taiwan
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27
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Shimoda LA, Welsh LE, Pearse DB. Inhibition of inwardly rectifying K(+) channels by cGMP in pulmonary vascular endothelial cells. Am J Physiol Lung Cell Mol Physiol 2002; 283:L297-304. [PMID: 12114190 DOI: 10.1152/ajplung.00469.2001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endothelial barrier dysfunction is typically triggered by increased intracellular Ca(2+) concentration. Membrane-permeable analogs of guanosine 3',5'-cyclic monophosphate (cGMP) prevent disruption of endothelial cell integrity. Because membrane potential (E(m)), which influences the electrochemical gradient for Ca(2+) influx, is regulated by K(+) channels, we investigated the effect of 8-bromo-cGMP on E(m) and inwardly rectifying K(+) (K(IR)) currents in bovine pulmonary artery and microvascular endothelial cells (BPAEC and BMVEC), using whole cell patch-clamp techniques. Both cell types exhibited inward currents at potentials negative to -50 mV that were abolished by application of 10 microM Ba(2+), consistent with K(IR) current. Ba(2+) also depolarized both cell types. 8-Bromo-cGMP (10(-3) M) depolarized BPAEC and BMVEC and inhibited K(IR) current. Pretreatment with Rp-8-cPCT-cGMPS or KT-5823, protein kinase G (PKG) antagonists, did not prevent current inhibition by 8-bromo-cGMP. These data suggest that 8-bromo-cGMP induces depolarization in BPAEC and BMVEC due, in part, to PKG-independent inhibition of K(IR) current. The depolarization could be a protective mechanism that prevents endothelial cell barrier dysfunction by reducing the driving force for Ca(2+) entry.
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Affiliation(s)
- Larissa A Shimoda
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland 21224, USA.
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Lien CC, Martina M, Schultz JH, Ehmke H, Jonas P. Gating, modulation and subunit composition of voltage-gated K(+) channels in dendritic inhibitory interneurones of rat hippocampus. J Physiol 2002; 538:405-19. [PMID: 11790809 PMCID: PMC2290075 DOI: 10.1113/jphysiol.2001.013066] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
GABAergic interneurones are diverse in their morphological and functional properties. Perisomatic inhibitory cells show fast spiking during sustained current injection, whereas dendritic inhibitory cells fire action potentials with lower frequency. We examined functional and molecular properties of K(+) channels in interneurones with horizontal dendrites in stratum oriens-alveus (OA) of the hippocampal CA1 region, which mainly comprise somatostatin-positive dendritic inhibitory cells. Voltage-gated K(+) currents in nucleated patches isolated from OA interneurones consisted of three major components: a fast delayed rectifier K(+) current component that was highly sensitive to external 4-aminopyridine (4-AP) and tetraethylammonium (TEA) (half-maximal inhibitory concentrations < 0.1 mM for both blockers), a slow delayed rectifier K(+) current component that was sensitive to high concentrations of TEA, but insensitive to 4-AP, and a rapidly inactivating A-type K(+) current component that was blocked by high concentrations of 4-AP, but resistant to TEA. The relative contributions of these components to the macroscopic K(+) current were estimated as 57 +/- 5, 25 +/- 6, and 19 +/- 2 %, respectively. Dendrotoxin, a selective blocker of Kv1 channels had only minimal effects on K(+) currents in nucleated patches. Coapplication of the membrane-permeant cAMP analogue 8-(4-chlorophenylthio)-adenosine 3':5'-cyclic monophosphate (cpt-cAMP) and the phosphodiesterase blocker isobutyl-methylxanthine (IBMX) resulted in a selective inhibition of the fast delayed rectifier K(+) current component. This inhibition was absent in the presence of the protein kinase A (PKA) inhibitor H-89, implying the involvement of PKA-mediated phosphorylation. Single-cell reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed a high abundance of Kv3.2 mRNA in OA interneurones, whereas the expression level of Kv3.1 mRNA was markedly lower. Similarly, RT-PCR analysis showed a high abundance of Kv4.3 mRNA, whereas Kv4.2 mRNA was undetectable. This suggests that the fast delayed rectifier K(+) current and the A-type K(+) current component are mediated predominantly by homomeric Kv3.2 and Kv4.3 channels. Selective modulation of Kv3.2 channels in OA interneurones by cAMP is likely to be an important factor regulating the activity of dendritic inhibitory cells in principal neurone-interneurone microcircuits.
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Affiliation(s)
- Cheng-Chang Lien
- Physiologisches Institut der Universität Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany
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Rudy B, McBain CJ. Kv3 channels: voltage-gated K+ channels designed for high-frequency repetitive firing. Trends Neurosci 2001; 24:517-26. [PMID: 11506885 DOI: 10.1016/s0166-2236(00)01892-0] [Citation(s) in RCA: 563] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Analysis of the Kv3 subfamily of K(+) channel subunits has lead to the discovery of a new class of neuronal voltage-gated K(+) channels characterized by positively shifted voltage dependencies and very fast deactivation rates. These properties are adaptations that allow these channels to produce currents that can specifically enable fast repolarization of action potentials without compromising spike initiation or height. The short spike duration and the rapid deactivation of the Kv3 currents after spike repolarization maximize the quick recovery of resting conditions after an action potential. Several neurons in the mammalian CNS have incorporated into their repertoire of voltage-dependent conductances a relatively large number of Kv3 channels to enable repetitive firing at high frequencies - an ability that crucially depends on the special properties of Kv3 channels and their impact on excitability.
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Affiliation(s)
- B Rudy
- Dept. of Physiology and Neuroscience, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
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