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Müller P, Draguhn A, Egorov AV. Persistent sodium currents in neurons: potential mechanisms and pharmacological blockers. Pflugers Arch 2024:10.1007/s00424-024-02980-7. [PMID: 38967655 DOI: 10.1007/s00424-024-02980-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Revised: 06/07/2024] [Accepted: 06/11/2024] [Indexed: 07/06/2024]
Abstract
Persistent sodium current (INaP) is an important activity-dependent regulator of neuronal excitability. It is involved in a variety of physiological and pathological processes, including pacemaking, prolongation of sensory potentials, neuronal injury, chronic pain and diseases such as epilepsy and amyotrophic lateral sclerosis. Despite its importance, neither the molecular basis nor the regulation of INaP are sufficiently understood. Of particular significance is a solid knowledge and widely accepted consensus about pharmacological tools for analysing the function of INaP and for developing new therapeutic strategies. However, the literature on INaP is heterogeneous, with varying definitions and methodologies used across studies. To address these issues, we provide a systematic review of the current state of knowledge on INaP, with focus on mechanisms and effects of this current in the central nervous system. We provide an overview of the specificity and efficacy of the most widely used INaP blockers: amiodarone, cannabidiol, carbamazepine, cenobamate, eslicarbazepine, ethosuximide, gabapentin, GS967, lacosamide, lamotrigine, lidocaine, NBI-921352, oxcarbazepine, phenytoine, PRAX-562, propofol, ranolazine, riluzole, rufinamide, topiramate, valproaic acid and zonisamide. We conclude that there is strong variance in the pharmacological effects of these drugs, and in the available information. At present, GS967 and riluzole can be regarded bona fide INaP blockers, while phenytoin and lacosamide are blockers that only act on the slowly inactivating component of sodium currents.
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Affiliation(s)
- Peter Müller
- Department Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen , Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
| | - Andreas Draguhn
- Institute for Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany
| | - Alexei V Egorov
- Institute for Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany
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2
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Zhang Z, Ding C, Fu R, Wang J, Zhao J, Zhu H. Low-frequency rTMS modulated the excitability and high-frequency firing in hippocampal neurons of the Alzheimer's disease mouse model. Brain Res 2024; 1831:148822. [PMID: 38408558 DOI: 10.1016/j.brainres.2024.148822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 02/05/2024] [Accepted: 02/21/2024] [Indexed: 02/28/2024]
Abstract
Repetitive transcranial magnetic stimulation (rTMS), a non-invasive brain stimulation technique, holds potential for applications in the treatment of Alzheimer's disease (AD). This study aims to compare the therapeutic effects of rTMS at different frequencies on Alzheimer's disease and explore the alterations in neuronal electrophysiological properties throughout this process. APP/PS1 AD mice were subjected to two rTMS treatments at 0.5 Hz and 20 Hz, followed by assessments of therapeutic outcomes through the Novel Object Recognition (NOR) and Morris Water Maze (MWM) tests. Following this, whole-cell patch-clamp techniques were used to record action potential, voltage-gated sodium channel currents, and voltage-gated potassium channel currents in dentate gyrus granule neurons. The results show that AD mice exhibit significant cognitive decline compared to normal mice, along with a pronounced reduction in neuronal excitability and ion channel activity. Both frequencies of rTMS treatment partially reversed these changes, demonstrating similar therapeutic efficacy. Furthermore, the investigation indicates that low-frequency magnetic stimulation inhibited the concentrated firing of early action potentials in AD.
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Affiliation(s)
- Ze Zhang
- School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin 300130, China; Hebei Key Laboratory of Bioelectromagnetics and Neural Engineering, Tianjin 300130, China.
| | - Chong Ding
- School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin 300130, China; Hebei Key Laboratory of Bioelectromagnetics and Neural Engineering, Tianjin 300130, China; State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin 300130, China.
| | - Rui Fu
- School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin 300130, China; Hebei Key Laboratory of Bioelectromagnetics and Neural Engineering, Tianjin 300130, China.
| | - Jiale Wang
- School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin 300130, China; Hebei Key Laboratory of Bioelectromagnetics and Neural Engineering, Tianjin 300130, China.
| | - Junqiao Zhao
- School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin 300130, China; Hebei Key Laboratory of Bioelectromagnetics and Neural Engineering, Tianjin 300130, China.
| | - Haijun Zhu
- Key Laboratory of Digital Medical Engineering of Hebei Province, College of Electronic & Information Engineering, Hebei University, Baoding, Hebei 071002, China.
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3
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Cho JH, Jang IS. Ibuprofen modulates tetrodotoxin-resistant persistent Na + currents at acidic pH in rat trigeminal ganglion neurons. Eur J Pharmacol 2023; 961:176218. [PMID: 37992887 DOI: 10.1016/j.ejphar.2023.176218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 11/13/2023] [Accepted: 11/16/2023] [Indexed: 11/24/2023]
Abstract
Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used to relieve various symptoms such as headache, arthralgia, and dental pain. While the primary mechanism of NSAID-based pain relief is the inhibition of cyclooxygenase-2, several NSAIDs also modulate other molecular targets related to nociceptive transmission such as voltage-gated Na+ channels. In the present study, we examined the effects of NSAIDs on persistent Na+ current (INaP) mediated by tetrodotoxin-resistant (TTX-R) Na+ channels in small-to medium-sized trigeminal ganglion neurons using a whole-cell patch-clamp technique. At clinically relevant concentrations, all propionic acid derivatives tested (ibuprofen, naproxen, fenoprofen, and flurbiprofen) preferentially inhibited the TTX-R INaP. The inhibition was more potent at acidic extracellular pH (pH 6.5) than at normal pH (pH 7.4). Other NSAIDs, such as ketorolac, piroxicam, and aspirin, had a negligible effect on the TTX-R INaP. Ibuprofen both accelerated the onset of inactivation and retarded the recovery from inactivation of TTX-R Na+ channels at acidic extracellular pH. However, all NSAIDs tested in this study had minor effects on voltage-gated K+ currents, as well as hyperpolarization-activated and cyclic nucleotide-gated cation currents, at both acidic and normal extracellular pH. Under current-clamp conditions, ibuprofen decreased the number of action potentials elicited by depolarizing current stimuli at acidic (pH 6.5) extracellular pH. Considering that extracellular pH falls as low as 5.5 in inflamed tissues, TTX-R INaP inhibition could be a mechanism by which ibuprofen and propionic acid derivative NSAIDs modulate inflammatory pain.
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Affiliation(s)
- Jin-Hwa Cho
- Department of Pharmacology, School of Dentistry, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu, 41940, Republic of Korea.
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4
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Tu YC, Chao FY, Tsai MF. Mechanisms of dual modulatory effects of spermine on the mitochondrial calcium uniporter complex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.06.543936. [PMID: 37333420 PMCID: PMC10274775 DOI: 10.1101/2023.06.06.543936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
The mitochondrial Ca 2 + uniporter mediates the crucial cellular process of mitochondrial Ca 2 + uptake, which regulates cell bioenergetics, intracellular Ca 2 + signaling, and cell death initiation. The uniporter contains the pore-forming MCU subunit, an EMRE protein that binds to MCU, and the regulatory MICU1 subunit, which can dimerize with MICU1 or MICU2 and under resting cellular [Ca 2 + ] occludes the MCU pore. It has been known for decades that spermine, which is ubiquitously present in animal cells, can enhance mitochondrial Ca 2 + uptake, but the underlying mechanisms remain unclear. Here, we show that spermine exerts dual modulatory effects on the uniporter. In physiological concentrations of spermine, it enhances uniporter activity by breaking the physical interactions between MCU and the MICU1-containing dimers to allow the uniporter to constitutively take up Ca 2 + even in low [Ca 2 + ] conditions. This potentiation effect does not require MICU2 or the EF-hand motifs in MICU1. When [spermine] rises to millimolar levels, it inhibits the uniporter by targeting the pore region in a MICU-independent manner. The MICU1-dependent spermine potentiation mechanism proposed here, along with our previous finding that cardiac mitochondria have very low MICU1, can explain the puzzling observation in the literature that mitochondria in the heart show no response to spermine.
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Affiliation(s)
- Yung-Chi Tu
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Fan-Yi Chao
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Ming-Feng Tsai
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
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Maksaev G, Yuan P, Nichols CG. Blockade of TRPV channels by intracellular spermine. J Gen Physiol 2023; 155:e202213273. [PMID: 36912700 PMCID: PMC10038874 DOI: 10.1085/jgp.202213273] [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] [Received: 09/29/2022] [Revised: 01/20/2023] [Accepted: 02/28/2023] [Indexed: 03/14/2023] Open
Abstract
The Vanilloid thermoTRP (TRPV1-4) subfamily of TRP channels are involved in thermoregulation, osmoregulation, itch and pain perception, (neuro)inflammation and immune response, and tight control of channel activity is required for perception of noxious stimuli and pain. Here we report voltage-dependent modulation of each of human TRPV1, 3, and 4 by the endogenous intracellular polyamine spermine. As in inward rectifier K channels, currents are blocked in a strongly voltage-dependent manner, but, as in cyclic nucleotide-gated channels, the blockade is substantially reduced at more positive voltages, with maximal blockade in the vicinity of zero voltage. A kinetic model of inhibition suggests two independent spermine binding sites with different affinities as well as different degrees of polyamine permeability in TRPV1, 3, and 4. Given that block and relief occur over the physiological voltage range of action potentials, voltage-dependent polyamine block may be a potent modulator of TRPV-dependent excitability in multiple cell types.
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Affiliation(s)
- Grigory Maksaev
- Department of Cell Biology and Physiology, Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Peng Yuan
- Department of Cell Biology and Physiology, Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Colin G. Nichols
- Department of Cell Biology and Physiology, Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO, USA
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Zhu H, Yin X, Yang H, Fu R, Hou W, Ding C, Xu G. Repetitive transcranial magnetic stimulation enhances the neuronal excitability of mice by regulating dynamic characteristics of Granule cells' Ion channels. Cogn Neurodyn 2023; 17:431-443. [PMID: 37007191 PMCID: PMC10050517 DOI: 10.1007/s11571-022-09837-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 04/22/2022] [Accepted: 05/15/2022] [Indexed: 11/26/2022] Open
Abstract
This study aims to explore the effects of acute high-frequency repetitive transcranial magnetic stimulation (hf-rTMS) on neuronal excitability of granule cells in the hippocampal dentate gyrus, as well as the underlying intrinsic mediating mechanisms by which rTMS regulates neuronal excitability. First, high-frequency single TMS was used to measure the motor threshold (MT) of mice. Then, rTMS with different intensities of 0 MT (control), 0.8 MT, and 1.2 MT were applied to acute mice brain slices. Next, patch-clamp technique was used to record the resting membrane potential and evoked nerve discharge of granule cells, as well as the voltage-gated sodium current (I Na) of voltage-gated sodium channels (VGSCs), transient outward potassium current (I A) and delayed rectifier potassium current (I K) of voltage-gated potassium channels (Kv). Results showed that acute hf-rTMS in both 0.8 MT and 1.2 MT groups significantly activated I Na and inhibited I A and I K compared with control group, due to the changes of dynamic characteristics of VGSCs and Kv. Acute hf-rTMS in both 0.8 MT and 1.2 MT groups significantly increased membrane potential and nerve discharge frequency. Therefore, changing dynamic characteristics of VGSCs and Kv, activating I Na and inhibiting I A and I K might be one of the intrinsic mediating mechanisms by which rTMS enhanced the neuronal excitability of granular cells, and this regulatory effect increased with the increase of stimulus intensity.
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Affiliation(s)
- Haijun Zhu
- Key Laboratory of Digital Medical Engineering of Hebei Province, College of Electronic and Information Engineering, Hebei University, Baoding, 071002 China
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Electrical Engineering, Hebei University of Technology, Tianjin, 300130 China
| | - Xiaonan Yin
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Electrical Engineering, Hebei University of Technology, Tianjin, 300130 China
| | - Huilan Yang
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Electrical Engineering, Hebei University of Technology, Tianjin, 300130 China
| | - Rui Fu
- Tianjin Key Laboratory of Bioelectromagnetic Technology and Intelligent Health, School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin, 300130 China
| | - Wentao Hou
- Tianjin Key Laboratory of Bioelectromagnetic Technology and Intelligent Health, School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin, 300130 China
| | - Chong Ding
- Tianjin Key Laboratory of Bioelectromagnetic Technology and Intelligent Health, School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin, 300130 China
| | - Guizhi Xu
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Electrical Engineering, Hebei University of Technology, Tianjin, 300130 China
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Kotler O, Khrapunsky Y, Shvartsman A, Dai H, Plant LD, Goldstein SAN, Fleidervish I. SUMOylation of Na V1.2 channels regulates the velocity of backpropagating action potentials in cortical pyramidal neurons. eLife 2023; 12:e81463. [PMID: 36794908 PMCID: PMC10014073 DOI: 10.7554/elife.81463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 02/15/2023] [Indexed: 02/17/2023] Open
Abstract
Voltage-gated sodium channels located in axon initial segments (AIS) trigger action potentials (AP) and play pivotal roles in the excitability of cortical pyramidal neurons. The differential electrophysiological properties and distributions of NaV1.2 and NaV1.6 channels lead to distinct contributions to AP initiation and propagation. While NaV1.6 at the distal AIS promotes AP initiation and forward propagation, NaV1.2 at the proximal AIS promotes the backpropagation of APs to the soma. Here, we show the small ubiquitin-like modifier (SUMO) pathway modulates Na+ channels at the AIS to increase neuronal gain and the speed of backpropagation. Since SUMO does not affect NaV1.6, these effects were attributed to SUMOylation of NaV1.2. Moreover, SUMO effects were absent in a mouse engineered to express NaV1.2-Lys38Gln channels that lack the site for SUMO linkage. Thus, SUMOylation of NaV1.2 exclusively controls INaP generation and AP backpropagation, thereby playing a prominent role in synaptic integration and plasticity.
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Affiliation(s)
- Oron Kotler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the NegevBeer ShevaIsrael
| | - Yana Khrapunsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the NegevBeer ShevaIsrael
| | - Arik Shvartsman
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the NegevBeer ShevaIsrael
| | - Hui Dai
- Departments of Pediatrics and Physiology and Biophysics, University of California, IrvineIrvineUnited States
| | - Leigh D Plant
- Department of Pharmaceutical Sciences, Northeastern UniversityBostonUnited States
| | - Steven AN Goldstein
- Departments of Pediatrics and Physiology and Biophysics, University of California, IrvineIrvineUnited States
| | - Ilya Fleidervish
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the NegevBeer ShevaIsrael
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Marcoli M, Cervetto C, Amato S, Fiorucci C, Maura G, Mariottini P, Cervelli M. Transgenic Mouse Overexpressing Spermine Oxidase in Cerebrocortical Neurons: Astrocyte Dysfunction and Susceptibility to Epileptic Seizures. Biomolecules 2022; 12:204. [PMID: 35204705 PMCID: PMC8961639 DOI: 10.3390/biom12020204] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/20/2022] [Accepted: 01/21/2022] [Indexed: 02/06/2023] Open
Abstract
Polyamines are organic polycations ubiquitously present in living cells. Polyamines are involved in many cellular processes, and their content in mammalian cells is tightly controlled. Among their function, these molecules modulate the activity of several ion channels. Spermine oxidase, specifically oxidized spermine, is a neuromodulator of several types of ion channel and ionotropic glutamate receptors, and its deregulated activity has been linked to several brain pathologies, including epilepsy. The Dach-SMOX mouse line was generated using a Cre/loxP-based recombination approach to study the complex and critical functions carried out by spermine oxidase and spermine in the mammalian brain. This mouse genetic model overexpresses spermine oxidase in the neocortex and is a chronic model of excitotoxic/oxidative injury and neuron vulnerability to oxidative stress and excitotoxic, since its phenotype revealed to be more susceptible to different acute oxidative insults. In this review, the molecular mechanisms underlined the Dach-SMOX phenotype, linked to reactive astrocytosis, neuron loss, chronic oxidative and excitotoxic stress, and susceptibility to seizures have been discussed in detail. The Dach-SMOX mouse model overexpressing SMOX may help in shedding lights on the susceptibility to epileptic seizures, possibly helping to understand the mechanisms underlying epileptogenesis in vulnerable individuals and contributing to provide new molecular mechanism targets to search for novel antiepileptic drugs.
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Affiliation(s)
- Manuela Marcoli
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genoa, Italy; (S.A.); (G.M.)
- Interuniversity Center for the Promotion of the 3Rs Principles in Teaching and Research (Centro 3R), Lucio Lazzarino 1, 56122 Pisa, Italy
| | - Chiara Cervetto
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genoa, Italy; (S.A.); (G.M.)
- Interuniversity Center for the Promotion of the 3Rs Principles in Teaching and Research (Centro 3R), Lucio Lazzarino 1, 56122 Pisa, Italy
| | - Sarah Amato
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genoa, Italy; (S.A.); (G.M.)
| | - Cristian Fiorucci
- Department of Science, University of Rome “Roma Tre”, Viale Marconi 446, 00146 Rome, Italy; (C.F.); (P.M.)
| | - Guido Maura
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148 Genoa, Italy; (S.A.); (G.M.)
| | - Paolo Mariottini
- Department of Science, University of Rome “Roma Tre”, Viale Marconi 446, 00146 Rome, Italy; (C.F.); (P.M.)
| | - Manuela Cervelli
- Department of Science, University of Rome “Roma Tre”, Viale Marconi 446, 00146 Rome, Italy; (C.F.); (P.M.)
- Neurodevelopment, Neurogenetics and Molecular Neurobiology Unit, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, 00143 Rome, Italy
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Shvartsman A, Kotler O, Stoler O, Khrapunsky Y, Melamed I, Fleidervish IA. Subcellular Distribution of Persistent Sodium Conductance in Cortical Pyramidal Neurons. J Neurosci 2021; 41:6190-6201. [PMID: 34099506 PMCID: PMC8287986 DOI: 10.1523/jneurosci.2989-20.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 04/19/2021] [Accepted: 05/27/2021] [Indexed: 11/21/2022] Open
Abstract
Cortical pyramidal neurons possess a persistent Na+ current (I NaP), which, in contrast to the larger transient current, does not undergo rapid inactivation. Although relatively quite small, I NaP is active at subthreshold voltages and therefore plays an important role in neuronal input-output processing. The subcellular distribution of channels responsible for I NaP and the mechanisms that render them persistent are not known. Using high-speed fluorescence Na+ imaging and whole-cell recordings in brain slices obtained from mice of either sex, we reconstructed the I NaP elicited by slow voltage ramps in soma and processes of cortical pyramidal neurons. We found that in all neuronal compartments, the relationship between persistent Na+ conductance and membrane voltage has the shape of a Boltzmann function. Although the density of channels underlying I NaP was about twofold lower in the axon initial segment (AIS) than in the soma, the axonal channels were activated by ∼10 mV less depolarization than were somatic channels. This difference in voltage dependence explains why, at functionally critical subthreshold voltages, most I NaP originates in the AIS. Finally, we show that endogenous polyamines constrain I NaP availability in both somatodendritic and axonal compartments of nondialyzed cortical neurons.SIGNIFICANCE STATEMENT The most salient characteristic of neuronal sodium channels is fast inactivation. However, a fraction of the sodium current does not inactivate. In cortical neurons, persistent current (I NaP) plays a prominent role in many important functions. Its subcellular distribution and generation mechanisms are, however, elusive. Using high-speed fluorescence Na+ imaging and electrical recordings, we reconstructed the I NaP in soma and processes of cortical pyramidal neurons. We found that at near-threshold voltages I NaP originates predominately from the axon, because of the distinctive voltage dependence of the underlying channels and not because of their high density. Finally, we show that the presence of endogenous polyamines significantly constrains I NaP availability in all compartments of nondialyzed cortical neurons.
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Affiliation(s)
- Arik Shvartsman
- Department of Physiology and Cell Biology, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Oron Kotler
- Department of Physiology and Cell Biology, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Ohad Stoler
- Department of Physiology and Cell Biology, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Yana Khrapunsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Israel Melamed
- Department of Neurosurgery, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Ilya A Fleidervish
- Department of Physiology and Cell Biology, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
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10
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Ghosh I, Sankhe R, Mudgal J, Arora D, Nampoothiri M. Spermidine, an autophagy inducer, as a therapeutic strategy in neurological disorders. Neuropeptides 2020; 83:102083. [PMID: 32873420 DOI: 10.1016/j.npep.2020.102083] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 06/18/2020] [Accepted: 07/26/2020] [Indexed: 02/06/2023]
Abstract
Spermidine is a naturally occurring endogenous polyamine synthesized from diamine putrescine. It is a well-known autophagy inducer that maintains cellular and neuronal homeostasis. Healthy brain development and function are dependent on brain polyamine concentration. Polyamines interact with the opioid system, glutamatergic signaling and neuroinflammation in the neuronal and glial compartments. Among the polyamines, spermidine is found highest in the human brain. Age-linked fluctuations in the spermidine levels may possibly contribute to the impairments in neural network and neurogenesis. Exogenously administered spermidine helps in the treatment of brain diseases. Further, current studies highlight the ability of spermidine to promote longevity by inducing autophagy. Still, the causal neuroprotective mechanism of spermidine in neuronal dysfunction remains unidentified. This review aims to summarize various neuroprotective effects of spermidine related to anti-aging/ anti-inflammatory properties and the prevention of neurotoxicity that helps in achieving beneficial effects in age-related neurological disorder. We also expose the signaling cascades modulated by spermidine which might result in therapeutic action. The present review highlights clinical studies along with in-vivo and in-vitro preclinical studies to provide a new dimension for the therapeutic potential of spermidine in neurological disorders.
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Affiliation(s)
- Indrani Ghosh
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India
| | - Runali Sankhe
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India
| | - Jayesh Mudgal
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India
| | - Devinder Arora
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; School of Pharmacy and Pharmacology, MHIQ, QUM Network, Griffith University, Gold Coast, Queensland, Australia
| | - Madhavan Nampoothiri
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India.
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Quantum mechanical study of human carbonic anhydrase II in complex with polyamines as novel inhibitors: Kinetic and thermodynamic investigation. COMPUT THEOR CHEM 2020. [DOI: 10.1016/j.comptc.2020.112911] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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12
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Malpica-Nieves CJ, Rivera-Aponte DE, Tejeda-Bayron FA, Mayor AM, Phanstiel O, Veh RW, Eaton MJ, Skatchkov SN. The involvement of polyamine uptake and synthesis pathways in the proliferation of neonatal astrocytes. Amino Acids 2020; 52:1169-1180. [PMID: 32816168 PMCID: PMC7908810 DOI: 10.1007/s00726-020-02881-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 08/10/2020] [Indexed: 12/18/2022]
Abstract
Polyamines (PAs), such as spermidine (SPD) and spermine (SPM), are essential to promote cell growth, survival, proliferation, and longevity. In the adult central nervous system (CNS), SPD and SPM are accumulated predominantly in healthy adult glial cells where PA synthesis is not present. To date, the accumulation and biosynthesis of PAs in developing astrocytes are not well understood. The purpose of the present study was to determine the contribution of uptake and/or synthesis of PAs using proliferation of neonatal astrocytes as an endpoint. We inhibited synthesis of PAs using α-difluoromethylornithine (DFMO; an inhibitor of the PA biosynthetic enzyme ornithine decarboxylase (ODC)) and inhibited uptake of PAs using trimer44NMe (PTI; a novel polyamine transport inhibitor). DFMO, but not PTI alone, blocked proliferation, suggesting that PA biosynthesis was present. Furthermore, exogenous administration of SPD rescued cell proliferation when PA synthesis was blocked by DFMO. When both synthesis and uptake of PAs were inhibited (DFMO + PTI), exogenous SPD no longer supported proliferation. These data indicate that neonatal astrocytes synthesize sufficient quantities of PAs de novo to support cell proliferation, but are also able to import exogenous PAs. This suggests that the PA uptake mechanism is present in both neonates as well as in adults and can support cell proliferation in neonatal astrocytes when ODC is blocked.
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Affiliation(s)
- Christian J Malpica-Nieves
- Department of Biochemistry, School of Medicine, Universidad Central del Caribe, P.O. Box 60327, Bayamón, PR, 00960-6032, USA
| | - David E Rivera-Aponte
- Department of Biochemistry, School of Medicine, Universidad Central del Caribe, P.O. Box 60327, Bayamón, PR, 00960-6032, USA
| | - Flavia A Tejeda-Bayron
- Department of Biochemistry, School of Medicine, Universidad Central del Caribe, P.O. Box 60327, Bayamón, PR, 00960-6032, USA
| | - Angel M Mayor
- Department of Internal Medicine, Universidad Central del Caribe, Bayamón, PR, 00956, USA
| | - Otto Phanstiel
- Department of Medical Education, University of Central Florida, Orlando, FL, 32816, USA
| | - Rüdiger W Veh
- Institut für Zell- Und Neurobiologie, Charité, 10117, Berlin, Germany
| | - Misty J Eaton
- Department of Biochemistry, School of Medicine, Universidad Central del Caribe, P.O. Box 60327, Bayamón, PR, 00960-6032, USA
| | - Serguei N Skatchkov
- Department of Biochemistry, School of Medicine, Universidad Central del Caribe, P.O. Box 60327, Bayamón, PR, 00960-6032, USA.
- Department of Physiology, School of Medicine, Universidad Central del Caribe, P.O. Box 60327, Bayamón, PR, 00960-6032, USA.
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13
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Dhara M, Matta JA, Lei M, Knowland D, Yu H, Gu S, Bredt DS. Polyamine regulation of ion channel assembly and implications for nicotinic acetylcholine receptor pharmacology. Nat Commun 2020; 11:2799. [PMID: 32493979 PMCID: PMC7271128 DOI: 10.1038/s41467-020-16629-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 05/15/2020] [Indexed: 01/31/2023] Open
Abstract
Small molecule polyamines are abundant in all life forms and participate in diverse aspects of cell growth and differentiation. Spermidine/spermine acetyltransferase (SAT1) is the rate-limiting enzyme in polyamine catabolism and a primary genetic risk factor for suicidality. Here, using genome-wide screening, we find that SAT1 selectively controls nicotinic acetylcholine receptor (nAChR) biogenesis. SAT1 specifically augments assembly of nAChRs containing α7 or α4β2, but not α6 subunits. Polyamines are classically studied as regulators of ion channel gating that engage the nAChR channel pore. In contrast, we find polyamine effects on assembly involve the nAChR cytosolic loop. Neurological studies link brain polyamines with neurodegenerative conditions. Our pharmacological and transgenic animal studies find that reducing polyamines enhances cortical neuron nAChR expression and augments nicotine-mediated neuroprotection. Taken together, we describe a most unexpected role for polyamines in regulating ion channel assembly, which provides a new avenue for nAChR neuropharmacology. Small molecule polyamines participate in diverse aspects of cell growth and differentiation and are known to regulate ion channel gating. Here authors reveal that cellular polyamines control nicotinic acetylcholine receptor (nAChR) biogenesis, and either catabolic degradation or inhibition of polyamine production augments nAChR assembly.
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Affiliation(s)
- Madhurima Dhara
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson and Johnson, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Jose A Matta
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson and Johnson, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Min Lei
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson and Johnson, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Daniel Knowland
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson and Johnson, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Hong Yu
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson and Johnson, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Shenyan Gu
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson and Johnson, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - David S Bredt
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson and Johnson, 3210 Merryfield Row, San Diego, CA, 92121, USA.
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14
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Moriyama Y, Hatano R, Moriyama S, Uehara S. Vesicular polyamine transporter as a novel player in amine-mediated chemical transmission. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183208. [PMID: 32004521 DOI: 10.1016/j.bbamem.2020.183208] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 01/23/2020] [Accepted: 01/26/2020] [Indexed: 02/06/2023]
Abstract
The solute carrier 18B1 (SLC18B1) is the most recently identified gene of the vesicular amine transporter family and is conserved in the animal kingdom from insects to humans. Proteoliposomes containing the purified human SLC18B1 protein transport not only monoamines, but also polyamines, such as spermidine (Spd) and spermine (Spm), using an electrochemical gradient of H+ established by vacuolar H+-ATPase (V-ATPase) as the driving force. SLC18B1 gene knockdown abolished the exocytosis of polyamines from mast cells, which affected the secretion of histamine. SLC18B1 gene knockout decreased polyamine levels by ~20% in the brain, and impaired short- and long-term memory. Thus, the SLC18B1 protein is responsible for the vesicular storage and release of polyamines, and functions as a vesicular polyamine transporter (VPAT). VPAT may define when, where, and how polyamine-mediated chemical transmission occurs, providing insights into the more versatile and complex features of amine-mediated chemical transmission than currently considered.
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Affiliation(s)
- Yoshinori Moriyama
- Department of Biochemistry, Matsumoto Dental University, Shiojiri 399-0781, Japan; Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Kurume 830-0011, Japan; CYRIC Tohoku University, Sendai 980-8578, Japan.
| | - Ryo Hatano
- Department of Medicinal Physiology, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan
| | - Satomi Moriyama
- Laboratory of Bio-Molecular Dynamics, Department of Collaborative Research, Nara Medical University, Kashihara 634-8521, Japan
| | - Shunsuke Uehara
- Department of Biochemistry, Matsumoto Dental University, Shiojiri 399-0781, Japan
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15
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Ozden A, Angelos H, Feyza A, Elizabeth W, John P. Altered plasma levels of arginine metabolites in depression. J Psychiatr Res 2020; 120:21-28. [PMID: 31629205 DOI: 10.1016/j.jpsychires.2019.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/23/2019] [Accepted: 10/03/2019] [Indexed: 02/07/2023]
Abstract
L-Arginine pathway metabolites appear to play differential roles in the pathogenesis of major depressive disorder (MDD). Studies have revealed an antidepressant and anxiolytic effect of agmatine and putrescine. Possible mechanisms of these effects include inhibition of nitric oxide synthase and N-methyl-D-aspartate receptors. The present study sought to determine whether MDD is associated with altered levels of arginine metabolites and whether these metabolites are associated with depression, anxiety and stress severity. Seventy seven MDD patients 21-65 years of age with a minimum score of 18 on the Hamilton Depression Scale, and 27 age and sex matched healthy controls (HC) were included. Patients with uncontrolled physical diseases, abnormal routine lab tests, other psychiatric diagnoses, or under psychotropic medication were excluded. HC subjects were recruited from the community. Rating instruments included Hamilton Depression and Anxiety Scales, Beck Depression and Anxiety Inventory and Perceived Stress Scale. Fasting blood was drawn between 8:30 and 11:00 a.m. and High Performance Liquid Chromatography (HPLC) was used to measure plasma arginine metabolites. ADMA (Asymmetrical dimethylarginine) and putrescine were significantly lower while SDMA (Symmetric dimethylarginine), agmatine and ornithine were significantly higher in MDD patients (p˂0.05). Depression, anxiety and stress severity were negatively correlated with ADMA and putrescine (p˂0.05). Stress was positively correlated with citrulline, NOHA (N-omega-hydroxy-nor-l-arginine), SDMA, agmatine and ornithine (p˂0.05). Lower putrescine levels predicted depression diagnosis (p = 0.039) and depression severity (p = 0.003). Low ADMA level predicted depression severity as well. Arginine pathway metabolites are associated with the pathophysiology of depression. Putrescine may be a biomarker to predict MDD.
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Affiliation(s)
- Arisoy Ozden
- Department of Psychiatry and Behavioral Neurosciences, Loyola University Stritch School of Medicine, Maywood, IL, USA; Department of Psychiatry, Bolu Abant Izzet Baysal University Medical Faculty, Bolu, Turkey
| | - Halaris Angelos
- Department of Psychiatry and Behavioral Neurosciences, Loyola University Stritch School of Medicine, Maywood, IL, USA.
| | - Aricioglu Feyza
- Department of Psychiatry and Behavioral Neurosciences, Loyola University Stritch School of Medicine, Maywood, IL, USA; Department of Pharmacology, Faculty of Pharmacy and Psychopharmacology Research Unit, Marmara University, Haydarpasa, Istanbul, Turkey
| | - Wild Elizabeth
- Department of Psychiatry and Behavioral Neurosciences, Loyola University Stritch School of Medicine, Maywood, IL, USA; Louisiana State University Health Sciences Center Shreveport, Department of Neurosurgery, USA
| | - Piletz John
- Department of Psychiatry and Behavioral Neurosciences, Loyola University Stritch School of Medicine, Maywood, IL, USA; Department of Biology, Missisipi College, Jackson, Missisipi, USA
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16
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Baroli G, Sanchez JR, Agostinelli E, Mariottini P, Cervelli M. Polyamines: The possible missing link between mental disorders and epilepsy (Review). Int J Mol Med 2019; 45:3-9. [PMID: 31746386 DOI: 10.3892/ijmm.2019.4401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 07/22/2019] [Indexed: 11/05/2022] Open
Abstract
Polyamines are small positively charged alkylamines that are essential in a number of crucial eukaryotic processes, like normal cell growth and development. In normal physiological conditions, intracellular polyamine content is tightly regulated through a fine regulated network of biosynthetic and catabolic enzymes and a transport system. The dysregulation of this network is frequently associated to different tumors, where high levels of polyamines has been detected. Polyamines also modulate ion channels and ionotropic glutamate receptors and altered levels of polyamines have been observed in different brain diseases, including mental disorders and epilepsy. The goal of this article is to review the role of polyamines in mental disorders and epilepsy within a frame of the possible link between these two brain pathologies. The high comorbidity between these two neurological illnesses is strongly suggestive that they share a common background in the central nervous system. This review proposes an additional association between the noradrenalin/serotonin and glutamatergic neuronal circuits with polyamines. Polyamines can be considered supplementary defensive shielding molecules, important to protect the brain from the development of epilepsy and mental illnesses that are caused by different types of neurons. In this contest, the modulation of polyamine metabolism may be a novel important target for the prevention and therapeutic treatment of these diseases that have a high impact on the costs of public health and considerably affect quality of life.
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Affiliation(s)
- Giulia Baroli
- Department of Science, University of Rome 'Roma Tre', I‑00146 Rome, Italy
| | | | - Enzo Agostinelli
- Department of Biochemical Sciences 'Rossi Fanelli', University of Rome 'La Sapienza', I‑00185 Rome, Italy
| | - Paolo Mariottini
- Department of Science, University of Rome 'Roma Tre', I‑00146 Rome, Italy
| | - Manuela Cervelli
- Department of Science, University of Rome 'Roma Tre', I‑00146 Rome, Italy
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17
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Polyamine Depletion Abrogates Enterovirus Cellular Attachment. J Virol 2019; 93:JVI.01054-19. [PMID: 31341056 DOI: 10.1128/jvi.01054-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 07/18/2019] [Indexed: 12/24/2022] Open
Abstract
Polyamines are small polycationic molecules with flexible carbon chains that are found in all eukaryotic cells. Polyamines are involved in the regulation of many host processes and have been shown to be implicated in viral replication. Depletion of polyamine pools in cells treated with FDA-approved drugs restricts replication of diverse RNA viruses. Viruses can exploit host polyamines to facilitate nucleic acid packaging, transcription, and translation, but other mechanisms remain largely unknown. Picornaviruses, including Coxsackievirus B3 (CVB3), are sensitive to the depletion of polyamines and remain a significant public health threat. We employed CVB3 as a model system to investigate a potential proviral role for polyamines using a forward screen. Passaging CVB3 in polyamine-depleted cells generated a mutation in capsid protein VP3 at residue 234. We show that this mutation confers resistance to polyamine depletion. Through attachment assays, we demonstrate that polyamine depletion limits CVB3 attachment to susceptible cells, which is rescued by incubating virus with polyamines. Furthermore, the capsid mutant rescues this inhibition in polyamine-depleted cells. More divergent viruses also exhibited reduced attachment to polyamine-depleted cells, suggesting that polyamines may facilitate attachment of diverse RNA viruses. These studies inform additional mechanisms of action for polyamine-depleting pharmaceuticals, with implications for potential antiviral therapies.IMPORTANCE Enteroviruses are significant human pathogens that can cause severe disease. These viruses rely on polyamines, small positively charged molecules, for robust replication, and polyamine depletion limits infection in vitro and in vivo The mechanisms by which polyamines enhance enteroviral replication are unknown. Here, we describe how Coxsackievirus B3 (CVB3) utilizes polyamines to attach to susceptible cells and initiate infection. Using a forward genetic screen, we identified a mutation in a receptor-binding amino acid that promotes infection of polyamine-depleted cells. These data suggest that pharmacologically inhibiting polyamine biosynthesis may combat virus infection by preventing virus attachment to susceptible cells.
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18
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Bozdag M, Altamimi ASA, Vullo D, Supuran CT, Carta F. State of the Art on Carbonic Anhydrase Modulators for Biomedical Purposes. Curr Med Chem 2019; 26:2558-2573. [PMID: 29932025 DOI: 10.2174/0929867325666180622120625] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 05/03/2018] [Accepted: 05/03/2018] [Indexed: 01/13/2023]
Abstract
The current review is intended to highlight recent advances in the search of new and effective modulators of the metalloenzymes Carbonic Anhydrases (CAs, EC 4.2.1.1) expressed in humans (h). CAs reversibly catalyze the CO2 hydration reaction, which is of crucial importance in the regulation of a plethora of fundamental processes at cellular level as well as in complex organisms. The first section of this review will be dedicated to compounds acting as activators of the hCAs (CAAs) and their promising effects on central nervous system affecting pathologies mainly characterized from memory and learning impairments. The second part will focus on the emerging chemical classes acting as hCA inhibitors (CAIs) and their potential use for the treatment of diseases.
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Affiliation(s)
- Murat Bozdag
- Universita degli Studi di Firenze, NEUROFARBA Dept., Sezione di Scienze Farmaceutiche e Nutraceutiche, Via Ugo Schiff 6, 50019 Sesto Fiorentino (Florence), Italy
| | - Abdulmalik Saleh Alfawaz Altamimi
- Department of Pharmaceutical Chemistry, College of Pharmacy, Prince Sattam Bin Abdulaziz University, PO Box 173, Alkharj 11942, Saudi Arabia
| | - Daniela Vullo
- Universita degli Studi di Firenze, NEUROFARBA Dept., Sezione di Scienze Farmaceutiche e Nutraceutiche, Via Ugo Schiff 6, 50019 Sesto Fiorentino (Florence), Italy
| | - Claudiu T Supuran
- Universita degli Studi di Firenze, NEUROFARBA Dept., Sezione di Scienze Farmaceutiche e Nutraceutiche, Via Ugo Schiff 6, 50019 Sesto Fiorentino (Florence), Italy
| | - Fabrizio Carta
- Universita degli Studi di Firenze, NEUROFARBA Dept., Sezione di Scienze Farmaceutiche e Nutraceutiche, Via Ugo Schiff 6, 50019 Sesto Fiorentino (Florence), Italy
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19
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Watts D, Pfaffenseller B, Wollenhaupt-Aguiar B, Paul Géa L, Cardoso TDA, Kapczinski F. Agmatine as a potential therapeutic intervention in bipolar depression: the preclinical landscape. Expert Opin Ther Targets 2019; 23:327-339. [DOI: 10.1080/14728222.2019.1581764] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Devon Watts
- Neuroscience Graduate Program, McMaster University, Hamilton, ON, Canada
| | - Bianca Pfaffenseller
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | | | - Luiza Paul Géa
- Graduate Program in Biological Sciences, Pharmacology and Therapeutics, Federal University of Rio Grande do Sul, UFRGS, Porto Alegre, Brazil
- Laboratory of Molecular Psychiatry, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil
| | | | - Flavio Kapczinski
- Neuroscience Graduate Program, McMaster University, Hamilton, ON, Canada
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
- Graduate Program in Psychiatry and Behavioral Sciences, Federal University of Rio Grande do Sul, UFRGS, Porto Alegre, Brazil
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20
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Derera ID, Dulla CG. THAR SHE BLOWS! The Search for the Great Spermine Whale of Carbamazepine Resistance. Epilepsy Curr 2019; 19:59-61. [PMID: 30838922 PMCID: PMC6610378 DOI: 10.1177/1535759718822034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Polyamine Modulation of Anticonvulsant Drug Response: A Potential
Mechanism Contributing to Pharmacoresistance in Chronic
Epilepsy Beckonert NM, Opitz T, Pitsch J, Soares da Silva P, Beck H. J
Neurosci. 2018;38(24):5596-5605. doi:10.1523/JNEUROSCI.0640-18.2018. Despite the development of numerous novel anticonvulsant drugs, ∼30% of
patients with epilepsy remain refractory to antiepileptic drugs (AEDs).
Many established and novel AEDs reduce hyperexcitability via voltage-
and use-dependent inhibition of voltage-gated Na+ channels.
For the widely used anticonvulsant carbamazepine (CBZ), use-dependent
block of Na+ channels is significantly reduced both in
experimental and human epilepsies. However, the molecular underpinnings
of this potential cellular mechanism for pharmacoresistance have
remained enigmatic. Here, we describe the mechanism that leads to the
emergence of CBZ-resistant Na+ channels. We focused on the
endogenous polyamine system, which powerfully modulates Na+
channels in a use-dependent manner. We had shown previously that the
intracellular polyamine spermine is reduced in chronic epilepsy,
resulting in increased persistent Na+ currents. Because both
spermine and CBZ bind use-dependently in spatial proximity within the
Na+ channel pore, we hypothesized that spermine loss
might also be related to diminished CBZ response. Using the pilocarpine
model of refractory epilepsy in male rats and whole-cell patch-clamp
recordings, we first replicated the reduction of use-dependent block by
CBZ in chronically epileptic animals. We then substituted intracellular
spermine via the patch pipette in different concentrations. Under these
conditions, we found that exogenous spermine significantly rescues
use-dependent block of Na+ channels by CBZ. These findings
indicate that an unexpected modulatory mechanism, depletion of
intracellular polyamines, leads both to increased persistent
Na+ currents and to diminished CBZ sensitivity of
Na+ channels. These findings could lead to novel
strategies for overcoming pharmacoresistant epilepsy that target the
polyamine system. Significance Statement: Pharmacoresistant epilepsy
affects ∼18 million people worldwide, and intense efforts have therefore
been undertaken to uncover the underlying molecular and cellular
mechanisms. One of the key known candidate mechanisms of
pharmacoresistance has been a loss of use-dependent Na+
channel block by the anticonvulsant CBZ, both in human and experimental
epilepsies. Despite intense scrutiny, the molecular mechanisms
underlying this phenomenon have not been elucidated. We now show that a
loss of intracellular spermine in chronic epilepsy is a major causative
factor leading to the development of CBZ-resistant Na+
currents. This finding can be exploited both for the screening of
anticonvulsants in expression systems and for novel strategies to
overcome pharmacoresistance that target the polyamine system.
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21
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Pietak A, Levin M. Bioelectrical control of positional information in development and regeneration: A review of conceptual and computational advances. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 137:52-68. [PMID: 29626560 PMCID: PMC10464501 DOI: 10.1016/j.pbiomolbio.2018.03.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 03/23/2018] [Accepted: 03/26/2018] [Indexed: 12/16/2022]
Abstract
Positional information describes pre-patterns of morphogenetic substances that alter spatio-temporal gene expression to instruct development of growth and form. A wealth of recent data indicate bioelectrical properties, such as the transmembrane potential (Vmem), are involved as instructive signals in the spatiotemporal regulation of morphogenesis. However, the mechanistic relationships between Vmem and molecular positional information are only beginning to be understood. Recent advances in computational modeling are assisting in the development of comprehensive frameworks for mechanistically understanding how endogenous bioelectricity can guide anatomy in a broad range of systems. Vmem represents an extraordinarily strong electric field (∼1.0 × 106 V/m) active over the thin expanse of the plasma membrane, with the capacity to influence a variety of downstream molecular signaling cascades. Moreover, in multicellular networks, intercellular coupling facilitated by gap junction channels may induce directed, electrodiffusive transport of charged molecules between cells of the network to generate new positional information patterning possibilities and characteristics. Given the demonstrated role of Vmem in morphogenesis, here we review current understanding of how Vmem can integrate with molecular regulatory networks to control single cell state, and the unique properties bioelectricity adds to transport phenomena in gap junction-coupled cell networks to facilitate self-assembly of morphogen gradients and other patterns. Understanding how Vmem integrates with biochemical regulatory networks at the level of a single cell, and mechanisms through which Vmem shapes molecular positional information in multicellular networks, are essential for a deep understanding of body plan control in development, regeneration and disease.
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Affiliation(s)
| | - Michael Levin
- Allen Discovery Center at Tufts, USA; Center for Regenerative and Developmental Biology, Tufts University, Medford, MA, USA
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22
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Polyamine Modulation of Anticonvulsant Drug Response: A Potential Mechanism Contributing to Pharmacoresistance in Chronic Epilepsy. J Neurosci 2018; 38:5596-5605. [PMID: 29789377 DOI: 10.1523/jneurosci.0640-18.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 05/07/2018] [Accepted: 05/12/2018] [Indexed: 11/21/2022] Open
Abstract
Despite the development of numerous novel anticonvulsant drugs, ∼30% of epilepsy patients remain refractory to antiepileptic drugs (AEDs). Many established and novel AEDs reduce hyperexcitability via voltage- and use-dependent inhibition of voltage-gated Na+ channels. For the widely used anticonvulsant carbamazepine (CBZ), use-dependent block of Na+ channels is significantly reduced both in experimental and human epilepsy. However, the molecular underpinnings of this potential cellular mechanism for pharmacoresistance have remained enigmatic.Here, we describe the mechanism that leads to the emergence of CBZ-resistant Na+ channels. We focused on the endogenous polyamine system, which powerfully modulates Na+ channels in a use-dependent manner. We had shown previously that the intracellular polyamine spermine is reduced in chronic epilepsy, resulting in increased persistent Na+ currents. Because spermine and CBZ both bind use-dependently in spatial proximity within the Na+ channel pore, we hypothesized that spermine loss might also be related to diminished CBZ response. Using the pilocarpine model of refractory epilepsy in male rats and whole-cell patch-clamp recordings, we first replicated the reduction of use-dependent block by CBZ in chronically epileptic animals. We then substituted intracellular spermine via the patch pipette in different concentrations. Under these conditions, we found that exogenous spermine significantly rescues use-dependent block of Na+ channels by CBZ. These findings indicate that an unexpected modulatory mechanism, depletion of intracellular polyamines, leads both to increased persistent Na+ currents and to diminished CBZ sensitivity of Na+ channels. These findings could lead to novel strategies for overcoming pharmacoresistant epilepsy that target the polyamine system.SIGNIFICANCE STATEMENT Pharmacoresistant epilepsy affects ∼18 million people worldwide, and intense efforts have therefore been undertaken to uncover the underlying molecular and cellular mechanisms. One of the key known candidate mechanisms of pharmacoresistance has been a loss of use-dependent Na+ channel block by the anticonvulsant carbamazepine (CBZ), both in human and experimental epilepsies. Despite intense scrutiny, the molecular mechanisms underlying this phenomenon have not been elucidated. We now show that a loss of intracellular spermine in chronic epilepsy is a major causative factor leading to the development of CBZ-resistant Na+ currents. This finding can be exploited both for the screening of anticonvulsants in expression systems, and for novel strategies to overcome pharmacoresistance that target the polyamine system.
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23
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Zheng Y, Dou JR, Dong L, Gao Y. Thermal effect induced by low-frequency magnetic field on physiological characteristics in hippocampal CA1 region of rat. Biomed Phys Eng Express 2017. [DOI: 10.1088/2057-1976/aa9686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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24
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Mutant α-Synuclein Overexpression Induces Stressless Pacemaking in Vagal Motoneurons at Risk in Parkinson's Disease. J Neurosci 2017; 37:47-57. [PMID: 28053029 DOI: 10.1523/jneurosci.1079-16.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 10/20/2016] [Accepted: 10/27/2016] [Indexed: 01/03/2023] Open
Abstract
α-Synuclein overexpression (ASOX) drives the formation of toxic aggregates in neurons vulnerable in Parkinson's disease (PD), including dopaminergic neurons of the substantia nigra (SN) and cholinergic neurons of the dorsal motor nucleus of the vagus (DMV). Just as these populations differ in when they exhibit α-synucleinopathies during PD pathogenesis, they could also differ in their physiological responses to ASOX. An ASOX-mediated hyperactivity of SN dopamine neurons, which was caused by oxidative dysfunction of Kv4.3 potassium channels, was recently identified in transgenic (A53T-SNCA) mice overexpressing mutated human α-synuclein. Noting that DMV neurons display extensive α-synucleinopathies earlier than SN dopamine neurons while exhibiting milder cell loss in PD, we aimed to define the electrophysiological properties of DMV neurons in A53T-SNCA mice. We found that DMV neurons maintain normal firing rates in response to ASOX. Moreover, Kv4.3 channels in DMV neurons exhibit no oxidative dysfunction in the A53T-SNCA mice, which could only be recapitulated in wild-type mice by glutathione dialysis. Two-photon imaging of redox-sensitive GFP corroborated the finding that mitochondrial oxidative stress was diminished in DMV neurons in the A53T-SNCA mice. This reduction in oxidative stress resulted from a transcriptional downregulation of voltage-activated (Cav) calcium channels in DMV neurons, which led to a reduction in activity-dependent calcium influx via Cav channels. Thus, ASOX induces a homeostatic remodeling with improved redox signaling in DMV neurons, which could explain the differential vulnerability of SN dopamine and DMV neurons in PD and could promote neuroprotective strategies that emulate endogenous homeostatic responses to ASOX (e.g., stressless pacemaking) in DMV neurons. SIGNIFICANCE STATEMENT Overexpression of mutant α-synuclein causes Parkinson's disease, presumably by driving neurodegeneration in vulnerable neuronal target populations. However, the extent of α-synuclein pathology (e.g., Lewy bodies) is not directly related to the degree of neurodegeneration across various vulnerable neuronal populations. Here, we show that, in contrast to dopamine neurons in the substantia nigra, vagal motoneurons do not enhance their excitability and oxidative load in response to chronic mutant α-synuclein overexpression. Rather, by downregulating their voltage-activated calcium channels, vagal motoneurons acquire a stressless form of pacemaking that diminishes mitochondrial and cytosolic oxidative stress. Emulating this endogenous adaptive response to α-synuclein overexpression could lead to novel strategies to protect dopamine neurons and perhaps delay the onset of Parkinson's disease.
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Ceci R, Duranti G, Leonetti A, Pietropaoli S, Spinozzi F, Marcocci L, Amendola R, Cecconi F, Sabatini S, Mariottini P, Cervelli M. Adaptive responses of heart and skeletal muscle to spermine oxidase overexpression: Evaluation of a new transgenic mouse model. Free Radic Biol Med 2017; 103:216-225. [PMID: 28043891 DOI: 10.1016/j.freeradbiomed.2016.12.040] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 12/22/2016] [Accepted: 12/26/2016] [Indexed: 12/16/2022]
Abstract
Spermine oxidase oxidizes spermine to produce H2O2, spermidine, and 3-aminopropanal. It is involved in cell drug response, apoptosis, and in the etiology of several pathologies, including cancer. Spermine oxidase is an important positive regulator of muscle gene expression and fiber size and, when repressed, leads to muscle atrophy. We have generated a transgenic mouse line overexpressing Smox gene in all organs, named Total-Smox. The spermine oxidase overexpression was revealed by β-Gal staining and reverse-transcriptase/PCR analysis, in all tissues analysed. Spermine oxidase activity resulted higher in Total-Smox than controls. Considering the important role of this enzyme in muscle physiology, we have focused our study on skeletal muscle and heart of Total-Smox mice by measuring redox status and oxidative damage. We assessed the redox homeostasis through the analysis of the reduced/oxidized glutathione ratio. Chronic H2O2 production induced by spermine oxidase overexpression leads to a cellular redox state imbalance in both tissues, although they show different redox adaptation. In skeletal muscle, catalase and glutathione S-transferase activities were significantly increased in Total-Smox mice compared to controls. In the heart, no differences were found in CAT activity level, while GST activity decreased compared to controls. The skeletal muscle showed a lower oxidative damage than in the heart, evaluated by lipid peroxidation and protein carbonylation. Altogether, our findings illustrate that skeletal muscle adapts more efficiently than heart to oxidative stress H2O2-induced. The Total-Smox line is a new genetic model useful to deepen our knowledge on the role of spermine oxidase in muscle atrophy and muscular pathological conditions like dystrophy.
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Affiliation(s)
- Roberta Ceci
- Unit of Biology, Genetics and Biochemistry, University of Rome "Foro Italico", Piazza Lauro De Bosis 15, 00135, Rome, Italy
| | - Guglielmo Duranti
- Unit of Biology, Genetics and Biochemistry, University of Rome "Foro Italico", Piazza Lauro De Bosis 15, 00135, Rome, Italy
| | | | | | | | - Lucia Marcocci
- Department of Biochemical Sciences 'A.Rossi Fanelli', La Sapienza University, Rome, Italy
| | | | - Francesco Cecconi
- Department of Biology, University of Rome 'Tor Vergata', 00133, Rome, Italy; Unit of Cell Stress and Survival, Danish Cancer Society Research Center, 2100, Copenhagen, Denmark
| | - Stefania Sabatini
- Unit of Biology, Genetics and Biochemistry, University of Rome "Foro Italico", Piazza Lauro De Bosis 15, 00135, Rome, Italy
| | | | - Manuela Cervelli
- Department of Sciences, Roma Tre Università, 00146, Rome, Italy.
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Shao H, Yang Y, Mi Z, Zhu GX, Qi AP, Ji WG, Zhu ZR. Anticonvulsant effect of Rhynchophylline involved in the inhibition of persistent sodium current and NMDA receptor current in the pilocarpine rat model of temporal lobe epilepsy. Neuroscience 2016; 337:355-369. [DOI: 10.1016/j.neuroscience.2016.09.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 09/12/2016] [Accepted: 09/16/2016] [Indexed: 01/28/2023]
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The earliest neuronal responses to hypoxia in the neocortical circuit are glutamate-dependent. Neurobiol Dis 2016; 95:158-67. [PMID: 27443966 DOI: 10.1016/j.nbd.2016.07.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 07/11/2016] [Accepted: 07/17/2016] [Indexed: 11/23/2022] Open
Abstract
Soon after exposure to hypoxia or ischemia, neurons in cortical tissues undergo massive anoxic depolarization (AD). This precipitous event is preceded by more subtle neuronal changes, including enhanced excitatory and inhibitory synaptic transmitter release. Here, we have used patch-in-slice techniques to identify the earliest effects of acute hypoxia on the synaptic and intrinsic properties of Layer 5 neurons, to determine their time course and to evaluate the role of glutamate receptors in their generation. Coronal slices of mouse somatosensory cortex were maintained at 36°C in an interface chamber and challenged with episodes of hypoxia. In recordings with cell-attached electrodes, the open probability of Ca(2+)-dependent BK channels began to increase within seconds of hypoxia onset, indicating a sharp rise in [Ca(2+)]i just beneath the membrane. By using a high concentration of K(+) in the pipette, we simultaneously monitored the membrane potential and showed that the [Ca(2+)]i rise was not associated with membrane depolarization. The earliest hypoxia-induced synaptic disturbance was a marked increase in the frequency of sPSCs, which also began soon after the removal of oxygen and long before AD. This synaptic effect was accompanied by depletion of the readily releasable transmitter pools, as demonstrated by a decreased response to hyperosmotic solutions. The early [Ca(2+)]i rise, the early increase in transmitter release and the subsequent AD itself were all prevented by bathing in a cocktail containing blockers of ionotropic glutamate receptors. We found no evidence for involvement of pannexin hemichannels or TRPM7 channels in the early responses to hypoxia in this experimental preparation. Our data indicate that the earliest cellular consequences of cortical hypoxia are triggered by activation of glutamate-gated channels.
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Skatchkov SN, Antonov SM, Eaton MJ. Glia and glial polyamines. Role in brain function in health and disease. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2016. [DOI: 10.1134/s1990747816010116] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Limon A, Mamdani F, Hjelm BE, Vawter MP, Sequeira A. Targets of polyamine dysregulation in major depression and suicide: Activity-dependent feedback, excitability, and neurotransmission. Neurosci Biobehav Rev 2016; 66:80-91. [PMID: 27108532 DOI: 10.1016/j.neubiorev.2016.04.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/09/2016] [Accepted: 04/13/2016] [Indexed: 01/19/2023]
Abstract
Major depressive disorder (MDD) is a leading cause of disability worldwide characterized by altered neuronal activity in brain regions involved in the control of stress and emotion. Although multiple lines of evidence suggest that altered stress-coping mechanisms underlie the etiology of MDD, the homeostatic control of neuronal excitability in MDD at the molecular level is not well established. In this review, we examine past and current evidence implicating dysregulation of the polyamine system as a central factor in the homeostatic response to stress and the etiology of MDD. We discuss the cellular effects of abnormal metabolism of polyamines in the context of their role in sensing and modulation of neuronal, electrical, and synaptic activity. Finally, we discuss evidence supporting an allostatic model of depression based on a chronic elevation in polyamine levels resulting in self-sustained stress response mechanisms maintained by maladaptive homeostatic mechanisms.
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Affiliation(s)
- Agenor Limon
- Functional Genomics Laboratory, Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92627, USA
| | - Firoza Mamdani
- Functional Genomics Laboratory, Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92627, USA
| | - Brooke E Hjelm
- Functional Genomics Laboratory, Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92627, USA
| | - Marquis P Vawter
- Functional Genomics Laboratory, Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92627, USA
| | - Adolfo Sequeira
- Functional Genomics Laboratory, Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92627, USA.
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Brown PMGE, Aurousseau MRP, Musgaard M, Biggin PC, Bowie D. Kainate receptor pore-forming and auxiliary subunits regulate channel block by a novel mechanism. J Physiol 2016; 594:1821-40. [PMID: 26682513 PMCID: PMC4818602 DOI: 10.1113/jp271690] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Accepted: 12/07/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Kainate receptor heteromerization and auxiliary subunits, Neto1 and Neto2, attenuate polyamine ion-channel block by facilitating blocker permeation. Relief of polyamine block in GluK2/GluK5 heteromers results from a key proline residue that produces architectural changes in the channel pore α-helical region. Auxiliary subunits exert an additive effect to heteromerization, and thus relief of polyamine block is due to a different mechanism. Our findings have broad implications for work on polyamine block of other cation-selective ion channels. ABSTRACT Channel block and permeation by cytoplasmic polyamines is a common feature of many cation-selective ion channels. Although the channel block mechanism has been studied extensively, polyamine permeation has been considered less significant as it occurs at extreme positive membrane potentials. Here, we show that kainate receptor (KAR) heteromerization and association with auxiliary proteins, Neto1 and Neto2, attenuate polyamine block by enhancing blocker permeation. Consequently, polyamine permeation and unblock occur at more negative and physiologically relevant membrane potentials. In GluK2/GluK5 heteromers, enhanced permeation is due to a single proline residue in GluK5 that alters the dynamics of the α-helical region of the selectivity filter. The effect of auxiliary proteins is additive, and therefore the structural basis of polyamine permeation and unblock is through a different mechanism. As native receptors are thought to assemble as heteromers in complex with auxiliary proteins, our data identify an unappreciated impact of polyamine permeation in shaping the signalling properties of neuronal KARs and point to a structural mechanism that may be shared amongst other cation-selective ion channels.
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Affiliation(s)
- Patricia M G E Brown
- Integrated Program in Neurosciences, McGill University, Montréal, Québec, Canada, H3G 0B1
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada, H3G 0B1
| | - Mark R P Aurousseau
- Graduate Program in Pharmacology, McGill University, Montréal, Québec, Canada, H3G 0B1
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada, H3G 0B1
| | - Maria Musgaard
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Philip C Biggin
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Derek Bowie
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada, H3G 0B1
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Cervetto C, Vergani L, Passalacqua M, Ragazzoni M, Venturini A, Cecconi F, Berretta N, Mercuri N, D'Amelio M, Maura G, Mariottini P, Voci A, Marcoli M, Cervelli M. Astrocyte-Dependent Vulnerability to Excitotoxicity in Spermine Oxidase-Overexpressing Mouse. Neuromolecular Med 2016; 18:50-68. [PMID: 26530396 DOI: 10.1007/s12017-015-8377-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/27/2015] [Indexed: 12/11/2022]
Abstract
Transgenic mice overexpressing spermine oxidase (SMO) in the cerebral cortex (Dach-SMO mice) showed increased vulnerability to excitotoxic brain injury and kainate-induced epileptic seizures. To investigate the mechanisms by which SMO overexpression leads to increased susceptibility to kainate excitotoxicity and seizure, in the cerebral cortex of Dach-SMO and control mice we assessed markers for astrocyte proliferation and neuron loss, and the ability of kainate to evoke glutamate release from nerve terminals and astrocyte processes. Moreover, we assessed a possible role of astrocytes in an in vitro model of epileptic-like activity in combined cortico-hippocampal slices recorded with a multi-electrode array device. In parallel, as the brain is a major metabolizer of oxygen and yet has relatively feeble protective antioxidant mechanisms, we analyzed the oxidative status of the cerebral cortex of both SMO-overexpressing and control mice by evaluating enzymatic and non-enzymatic scavengers such as metallothioneins. The main findings in the cerebral cortex of Dach-SMO mice as compared to controls are the following: astrocyte activation and neuron loss; increased oxidative stress and activation of defense mechanisms involving both neurons and astrocytes; increased susceptibility to kainate-evoked cortical epileptogenic activity, dependent on astrocyte function; appearance of a glutamate-releasing response to kainate from astrocyte processes due to activation of Ca(2+)-permeable AMPA receptors in Dach-SMO mice. We conclude that reactive astrocytosis and activation of glutamate release from astrocyte processes might contribute, together with increased reactive oxygen species production, to the vulnerability to kainate excitotoxicity in Dach-SMO mice. This mouse model with a deregulated polyamine metabolism would shed light on roles for astrocytes in increasing vulnerability to excitotoxic neuron injury.
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Affiliation(s)
- Chiara Cervetto
- Section of Pharmacology and Toxicology, Department of Pharmacy, University of Genova, Viale Cembrano 4, 16148, Genoa, Italy
- Center of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV 5, 16132, Genoa, Italy
| | - Laura Vergani
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genova, Corso Europa 26, 16132, Genoa, Italy
| | - Mario Passalacqua
- Department of Experimental Medicine, University of Genova, Via L. B. Alberti 2, 16132, Genoa, Italy
| | - Milena Ragazzoni
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genova, Corso Europa 26, 16132, Genoa, Italy
| | - Arianna Venturini
- Section of Pharmacology and Toxicology, Department of Pharmacy, University of Genova, Viale Cembrano 4, 16148, Genoa, Italy
| | - Francesco Cecconi
- Department of Biology, University of Rome 'Tor Vergata', Via della Ricerca Scientifica, 00133, Rome, Italy
- Department of Experimental Neurosciences, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, 00143, Rome, Italy
- Unit of Cell Stress and Survival, Danish Cancer Society Research Center, Strandboulevarden 49, 2100, Copenhagen, Denmark
| | - Nicola Berretta
- Department of Experimental Neurosciences, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, 00143, Rome, Italy
| | - Nicola Mercuri
- Department of Experimental Neurosciences, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, 00143, Rome, Italy
- Department of Systems Medicine, University of Rome 'Tor Vergata', Viale Oxford 81, 00133, Rome, Italy
| | - Marcello D'Amelio
- Department of Experimental Neurosciences, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, 00143, Rome, Italy
- Medical School Campus, Bio-Medico University of Rome, Via Alvaro del Portillo 21, 00128, Rome, Italy
| | - Guido Maura
- Section of Pharmacology and Toxicology, Department of Pharmacy, University of Genova, Viale Cembrano 4, 16148, Genoa, Italy
- Center of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV 5, 16132, Genoa, Italy
| | - Paolo Mariottini
- Department of Sciences, University of Rome "Roma Tre", Viale Marconi 446, 00146, Rome, Italy
- Interuniversity Consortium of Structural and Systems Biology, Viale Medaglie d'Oro 305, 00136, Rome, Italy
| | - Adriana Voci
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genova, Corso Europa 26, 16132, Genoa, Italy
| | - Manuela Marcoli
- Section of Pharmacology and Toxicology, Department of Pharmacy, University of Genova, Viale Cembrano 4, 16148, Genoa, Italy.
- Center of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV 5, 16132, Genoa, Italy.
| | - Manuela Cervelli
- Department of Sciences, University of Rome "Roma Tre", Viale Marconi 446, 00146, Rome, Italy.
- Interuniversity Consortium of Structural and Systems Biology, Viale Medaglie d'Oro 305, 00136, Rome, Italy.
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Igelhorst BA, Niederkinkhaus V, Karus C, Lange MD, Dietzel ID. Regulation of neuronal excitability by release of proteins from glial cells. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2014.0194. [PMID: 26009773 DOI: 10.1098/rstb.2014.0194] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Effects of glial cells on electrical isolation and shaping of synaptic transmission between neurons have been extensively studied. Here we present evidence that the release of proteins from astrocytes as well as microglia may regulate voltage-activated Na(+) currents in neurons, thereby increasing excitability and speed of transmission in neurons kept at distance from each other by specialized glial cells. As a first example, we show that basic fibroblast growth factor and neurotrophin-3, which are released from astrocytes by exposure to thyroid hormone, influence each other to enhance Na(+) current density in cultured hippocampal neurons. As a second example, we show that the presence of microglia in hippocampal cultures can upregulate Na(+) current density. The effect can be boosted by lipopolysaccharides, bacterial membrane-derived stimulators of microglial activation. Comparable effects are induced by the exposure of neuron-enriched hippocampal cultures to tumour necrosis factor-α, which is released from stimulated microglia. Taken together, our findings suggest that release of proteins from various types of glial cells can alter neuronal excitability over a time course of several days. This explains changes in neuronal excitability occurring in states of thyroid hormone imbalance and possibly also in seizures triggered by infectious diseases.
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Affiliation(s)
- Birte A Igelhorst
- Department of Biochemistry II, Ruhr University Bochum, Universitätsstraße 150, Bochum 44780, Germany
| | - Vanessa Niederkinkhaus
- Department of Biochemistry II, Ruhr University Bochum, Universitätsstraße 150, Bochum 44780, Germany International Graduate School for Neuroscience, Ruhr University Bochum, Universitätsstraße 150, Bochum 44780, Germany
| | - Claudia Karus
- Department of Biochemistry II, Ruhr University Bochum, Universitätsstraße 150, Bochum 44780, Germany
| | - Maren D Lange
- Department of Biochemistry II, Ruhr University Bochum, Universitätsstraße 150, Bochum 44780, Germany
| | - Irmgard D Dietzel
- Department of Biochemistry II, Ruhr University Bochum, Universitätsstraße 150, Bochum 44780, Germany
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Abela L, Simmons L, Steindl K, Schmitt B, Mastrangelo M, Joset P, Papuc M, Sticht H, Baumer A, Crowther LM, Mathis D, Rauch A, Plecko B. N(8)-acetylspermidine as a potential plasma biomarker for Snyder-Robinson syndrome identified by clinical metabolomics. J Inherit Metab Dis 2016; 39:131-7. [PMID: 26174906 DOI: 10.1007/s10545-015-9876-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 06/16/2015] [Accepted: 06/16/2015] [Indexed: 11/26/2022]
Abstract
Clinical metabolomics has emerged as a powerful tool to study human metabolism in health and disease. Comparative statistical analysis of untargeted metabolic profiles can reveal perturbations of metabolite levels in diseases and thus has the potential to identify novel biomarkers. Here we have applied a simultaneous genetic-metabolomic approach in twin boys with epileptic encephalopathy of unclear etiology. Clinical exome sequencing identified a novel missense mutation in the spermine synthase gene (SMS) that causes Snyder-Robinson syndrome (SRS). Untargeted plasma metabolome analysis revealed significantly elevated levels of N(8)-acetylspermidine, a precursor derivative of spermine biosynthesis, as a potential novel plasma biomarker for SRS. This result was verified in a third patient with genetically confirmed SRS. This study illustrates the potential of metabolomics as a translational technique to support exome data on a functional and clinical level.
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Affiliation(s)
- Lucia Abela
- Division of Child Neurology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Children's Research Centre, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - Luke Simmons
- Division of Child Neurology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Children's Research Centre, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - Katharina Steindl
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Institute of Medical Genetics, University of Zurich, Wagistrasse 12, 8952, Schlieren, Switzerland
| | - Bernhard Schmitt
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Division of Epilepsy and Neurophysiology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - Massimo Mastrangelo
- Pediatric Neurology Unit, V. Buzzi Children's Hospital, ICP, Via Castelvetro 24, 20154, Milan, Italy
| | - Pascal Joset
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Institute of Medical Genetics, University of Zurich, Wagistrasse 12, 8952, Schlieren, Switzerland
| | - Mihaela Papuc
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Institute of Medical Genetics, University of Zurich, Wagistrasse 12, 8952, Schlieren, Switzerland
| | - Heinrich Sticht
- Institute for Biochemistry, University of Erlangen-Nuernberg, Fahrstrasse 17, 91054, Erlangen, Germany
| | - Alessandra Baumer
- Institute of Medical Genetics, University of Zurich, Wagistrasse 12, 8952, Schlieren, Switzerland
| | - Lisa M Crowther
- Division of Child Neurology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Children's Research Centre, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - Déborah Mathis
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - Anita Rauch
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland
- Institute of Medical Genetics, University of Zurich, Wagistrasse 12, 8952, Schlieren, Switzerland
| | - Barbara Plecko
- Division of Child Neurology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland.
- Children's Research Centre, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland.
- Radiz-Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland.
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Levy N, Milikovsky DZ, Baranauskas G, Vinogradov E, David Y, Ketzef M, Abutbul S, Weissberg I, Kamintsky L, Fleidervish I, Friedman A, Monsonego A. Differential TGF-β Signaling in Glial Subsets Underlies IL-6-Mediated Epileptogenesis in Mice. THE JOURNAL OF IMMUNOLOGY 2015; 195:1713-22. [PMID: 26136430 DOI: 10.4049/jimmunol.1401446] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 06/02/2015] [Indexed: 01/01/2023]
Abstract
TGF-β1 is a master cytokine in immune regulation, orchestrating both pro- and anti-inflammatory reactions. Recent studies show that whereas TGF-β1 induces a quiescent microglia phenotype, it plays a pathogenic role in the neurovascular unit and triggers neuronal hyperexcitability and epileptogenesis. In this study, we show that, in primary glial cultures, TGF-β signaling induces rapid upregulation of the cytokine IL-6 in astrocytes, but not in microglia, via enhanced expression, phosphorylation, and nuclear translocation of SMAD2/3. Electrophysiological recordings show that administration of IL-6 increases cortical excitability, culminating in epileptiform discharges in vitro and spontaneous seizures in C57BL/6 mice. Intracellular recordings from layer V pyramidal cells in neocortical slices obtained from IL-6 -: treated mice show that during epileptogenesis, the cells respond to repetitive orthodromic activation with prolonged after-depolarization with no apparent changes in intrinsic membrane properties. Notably, TGF-β1 -: induced IL-6 upregulation occurs in brains of FVB/N but not in brains of C57BL/6 mice. Overall, our data suggest that TGF-β signaling in the brain can cause astrocyte activation whereby IL-6 upregulation results in dysregulation of astrocyte -: neuronal interactions and neuronal hyperexcitability. Whereas IL-6 is epileptogenic in C57BL/6 mice, its upregulation by TGF-β1 is more profound in FVB/N mice characterized as a relatively more susceptible strain to seizure-induced cell death.
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Affiliation(s)
- Nitzan Levy
- Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; Department of Physiology and Cell Biology, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel: and
| | - Dan Z Milikovsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel: and
| | - Gytis Baranauskas
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel: and
| | - Ekaterina Vinogradov
- Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Yaron David
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel: and
| | - Maya Ketzef
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel: and
| | - Shai Abutbul
- Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Itai Weissberg
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel: and
| | - Lyn Kamintsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel: and
| | - Ilya Fleidervish
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel: and
| | - Alon Friedman
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel: and Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Alon Monsonego
- Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel;
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Gorelova N, Seamans JK. Cell-attached single-channel recordings in intact prefrontal cortex pyramidal neurons reveal compartmentalized D1/D5 receptor modulation of the persistent sodium current. Front Neural Circuits 2015; 9:4. [PMID: 25729354 PMCID: PMC4325928 DOI: 10.3389/fncir.2015.00004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 01/08/2015] [Indexed: 11/28/2022] Open
Abstract
The persistent Na+ current (INap) is believed to be an important target of dopamine modulation in prefrontal cortex (PFC) neurons. While past studies have tested the effects of dopamine on INap, the results have been contradictory largely because of difficulties in measuring INap using somatic whole-cell recordings. To circumvent these confounds we used the cell-attached patch-clamp technique to record single Na+ channels from the soma, proximal dendrite (PD) or proximal axon (PA) of intact prefrontal layer V pyramidal neurons. Under baseline conditions, numerous well resolved Na+ channel openings were recorded that exhibited an extrapolated reversal potential of 73 mV, a slope conductance of 14–19 pS and were blocked by tetrodotoxin (TTX). While similar in most respects, the propensity to exhibit prolonged bursts lasting >40 ms was many fold greater in the axon than the soma or dendrite. Bath application of the D1/D5 receptor agonist SKF81297 shifted the ensemble current activation curve leftward and increased the number of late events recorded from the PD but not the soma or PA. However, the greatest effect was on prolonged bursting where the D1/D5 receptor agonist increased their occurrence 3 fold in the PD and nearly 7 fold in the soma, but not at all in the PA. As a result, D1/D5 receptor activation equalized the probability of prolonged burst occurrence across the proximal axosomatodendritic region. Therefore, D1/D5 receptor modulation appears to be targeted mainly to Na+ channels in the PD/soma and not the PA. By circumventing the pitfalls of previous attempts to study the D1/D5 receptor modulation of INap, we demonstrate conclusively that D1/D5 receptor activation can increase the INap generated proximally, however questions still remain as to how D1/D5 receptor modulates Na+ currents in the more distal initial segment where most of the INap is normally generated.
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Affiliation(s)
- Natalia Gorelova
- Department of Psychiatry and Brain Research Centre, University of British Columbia Vancouver, BC, Canada
| | - Jeremy K Seamans
- Department of Psychiatry and Brain Research Centre, University of British Columbia Vancouver, BC, Canada
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Identification of a mammalian vesicular polyamine transporter. Sci Rep 2014; 4:6836. [PMID: 25355561 PMCID: PMC4213795 DOI: 10.1038/srep06836] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 10/10/2014] [Indexed: 01/11/2023] Open
Abstract
Spermine and spermidine act as neuromodulators upon binding to the extracellular site(s) of various ionotropic receptors, such as N-methyl-d-aspartate receptors. To gain access to the receptors, polyamines synthesized in neurons and astrocytes are stored in secretory vesicles and released upon depolarization. Although vesicular storage is mediated in an ATP-dependent, reserpine-sensitive fashion, the transporter responsible for this process remains unknown. SLC18B1 is the fourth member of the SLC18 transporter family, which includes vesicular monoamine transporters and vesicular acetylcholine transporter. Proteoliposomes containing purified human SLC18B1 protein actively transport spermine and spermidine by exchange of H(+). SLC18B1 protein is predominantly expressed in the hippocampus and is associated with vesicles in astrocytes. SLC18B1 gene knockdown decreased both SLC18B1 protein and spermine/spermidine contents in astrocytes. These results indicated that SLC18B1 encodes a vesicular polyamine transporter (VPAT).
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Natural product polyamines that inhibit human carbonic anhydrases. BIOMED RESEARCH INTERNATIONAL 2014; 2014:374079. [PMID: 25162012 PMCID: PMC4138887 DOI: 10.1155/2014/374079] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 07/14/2014] [Indexed: 12/29/2022]
Abstract
Natural product compound collections have proven an effective way to access chemical diversity and recent findings have identified phenolic, coumarin, and polyamine natural products as atypical chemotypes that inhibit carbonic anhydrases (CAs). CA enzymes are implicated as targets of variable drug therapeutic classes and the discovery of selective, drug-like CA inhibitors is essential. Just two natural product polyamines, spermine and spermidine, have until now been investigated as CA inhibitors. In this study, five more complex natural product polyamines 1–5, derived from either marine sponge or fungi, were considered for inhibition of six different human CA isozymes of interest in therapeutic drug development. All compounds share a simple polyamine core fragment, either spermine or spermidine, yet display substantially different structure activity relationships for CA inhibition. Notably, polyamines 1–5 were submicromolar inhibitors of the cancer drug target CA IX, this is more potent than either spermine or spermidine.
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Park MH, Igarashi K. Polyamines and their metabolites as diagnostic markers of human diseases. Biomol Ther (Seoul) 2014; 21:1-9. [PMID: 24009852 PMCID: PMC3762300 DOI: 10.4062/biomolther.2012.097] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 01/04/2013] [Indexed: 01/31/2023] Open
Abstract
Polyamines, putrescine, spermidine and spermine, are ubiquitous in living cells and are essential for eukaryotic cell growth. These polycations interact with negatively charged molecules such as DNA, RNA, acidic proteins and phospholipids and modulate various cellular functions including macromolecular synthesis. Dysregulation of the polyamine pathway leads to pathological conditions including cancer, inflammation, stroke, renal failure and diabetes. Increase in polyamines and polyamine synthesis enzymes is often associated with tumor growth, and urinary and plasma contents of polyamines and their metabolites have been investigated as diagnostic markers for cancers. Of these, diacetylated derivatives of spermidine and spermine are elevated in the urine of cancer patients and present potential markers for early detection. Enhanced catabolism of cellular polyamines by polyamine oxidases (PAO), spermine oxidase (SMO) or acetylpolyamine oxidase (AcPAO), increases cellular oxidative stress and generates hydrogen peroxide and a reactive toxic metabolite, acrolein, which covalently incorporates into lysine residues of cellular proteins. Levels of protein-conjuagated acrolein (PC-Acro) and polyamine oxidizing enzymes were increased in the locus of brain infarction and in plasma in a mouse model of stroke and also in the plasma of stroke patients. When the combined measurements of PC-Acro, interleukin 6 (IL-6), and C-reactive protein (CRP) were evaluated, even silent brain infarction (SBI) was detected with high sensitivity and specificity. Considering that there are no reliable biochemical markers for early stage of stroke, PC-Acro and PAOs present promising markers. Thus the polyamine metabolites in plasma or urine provide useful tools in early diagnosis of cancer and stroke.
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Affiliation(s)
- Myung Hee Park
- Oral and Pharyngeal Cancer Branch, NIDCR, National Institutes of Health, Bethesda, MD, 20892, USA
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Abstract
The chemical diversity, binding specificity and propensity to interact with biological targets has inspired many researchers to utilize natural products as molecular probes. Almost all reported carbonic anhydrase inhibitors comprise a zinc binding group in their structure of which the primary sulfonamide moiety (-SO2NH2) is the foremost example and to a lesser extent the primary sulfamate (-O-SO2NH2) and sulfamide (-NH-SO2NH2) groups. Natural products that comprise these zinc binding groups in their structure are however rare and relatively few natural products have been explored as a source for novel carbonic anhydrase inhibitors. This chapter will highlight the recent and growing interest in carbonic anhydrase inhibitors sourced from nature, demonstrating that natural product chemical space presents a rich source of potential alternate chemotypes for the discovery of novel drug-like carbonic anhydrase inhibitors.
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Capone C, Cervelli M, Angelucci E, Colasanti M, Macone A, Mariottini P, Persichini T. A role for spermine oxidase as a mediator of reactive oxygen species production in HIV-Tat-induced neuronal toxicity. Free Radic Biol Med 2013; 63:99-107. [PMID: 23665428 DOI: 10.1016/j.freeradbiomed.2013.05.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Revised: 03/05/2013] [Accepted: 05/02/2013] [Indexed: 01/20/2023]
Abstract
Chronic oxidative stress, which occurs in brain tissues of HIV-infected patients, is involved in the pathogenesis of HIV-associated dementia. Oxidative stress can be induced by HIV-1-secreted proteins, either directly or indirectly through the release of cytotoxic factors. In particular, HIV-1 Tat is able to induce neuronal death by interacting with and activating the polyamine-sensitive subtype of the NMDA receptor (NMDAR). Here, we focused on the role of polyamine catabolism in Tat-induced oxidative stress in human neuroblastoma (SH-SY5Y) cells. First, Tat was found to induce reactive oxygen species production and to affect cell viability in SH-SY5Y cells, these effects being mediated by spermine oxidase (SMO). Second, Tat was observed to increase SMO activity as well as decreasing the intracellular spermine levels. Third, Tat-induced SMO activation was completely prevented by the NMDAR antagonist MK-801, clearly indicating an involvement of NMDAR stimulation. Finally, pretreatment of cells with N-acetylcysteine, a scavenger of H₂O₂, and with MK-801 was able to completely inhibit reactive oxygen species formation and to restore cell viability. Altogether, these data strongly suggest a role for polyamine catabolism-derived H₂O₂ in neurotoxicity as elicited by Tat-stimulated NMDAR.
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Affiliation(s)
- Caterina Capone
- Department of Science, University Roma Tre, 00146 Rome, Italy
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Choomuenwai V, Schwartz BD, Beattie KD, Andrews KT, Khokhar S, Davis RA. The discovery, synthesis and antimalarial evaluation of natural product-based polyamine alkaloids. Tetrahedron Lett 2013. [DOI: 10.1016/j.tetlet.2013.07.058] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Inflammation, carcinogenesis and neurodegeneration studies in transgenic animal models for polyamine research. Amino Acids 2013; 46:521-30. [PMID: 23933909 DOI: 10.1007/s00726-013-1572-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 07/26/2013] [Indexed: 12/18/2022]
Abstract
Natural polyamines (PA) are cationic molecules affecting cell growth and proliferation. An association between increased polyamine biosynthesis and inflammation-induced carcinogenesis has been recognised. On the other hand, there are indications that inflammatory stimuli can up-regulate polyamine catabolism and that altered polyamine metabolism could affect pro- and anti-inflammatory cytokines. Since the polyamine content is strictly related to cell growth, a consistent number of evidences relate polyamine metabolism dysfunction with cancer. The increase of polyamine levels in malignant and proliferating cells attracted the interest of scientists during last decades, addressing polyamine depletion as a new strategy to inhibit carcinogenesis. Several studies suggest that PA also play an important role in neurodegeneration, but the mechanisms by which they participate in neuronal death are still unclear. Furthermore, the role of endogenous PA in normal brain functioning is yet to be elucidated. The consequences of an alteration of polyamine metabolism have also been approached in vivo with the use of transgenic animals overexpressing or devoid of some enzymes involved in polyamine metabolism. In the present work we review the experimental investigation carried out on inflammation, cancerogenesis and neurodegeneration using transgenic animals engineered as models for polyamine research.
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Cervelli M, Bellavia G, D'Amelio M, Cavallucci V, Moreno S, Berger J, Nardacci R, Marcoli M, Maura G, Piacentini M, Amendola R, Cecconi F, Mariottini P. A New Transgenic Mouse Model for Studying the Neurotoxicity of Spermine Oxidase Dosage in the Response to Excitotoxic Injury. PLoS One 2013; 8:e64810. [PMID: 23840306 PMCID: PMC3686797 DOI: 10.1371/journal.pone.0064810] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 04/18/2013] [Indexed: 11/18/2022] Open
Abstract
Spermine oxidase is a FAD-containing enzyme involved in polyamines catabolism, selectively oxidizing spermine to produce H2O2, spermidine, and 3-aminopropanal. Spermine oxidase is highly expressed in the mouse brain and plays a key role in regulating the levels of spermine, which is involved in protein synthesis, cell division and cell growth. Spermine is normally released by neurons at synaptic sites where it exerts a neuromodulatory function, by specifically interacting with different types of ion channels, and with ionotropic glutamate receptors. In order to get an insight into the neurobiological roles of spermine oxidase and spermine, we have deregulated spermine oxidase gene expression producing and characterizing the transgenic mouse model JoSMOrec, conditionally overexpressing the enzyme in the neocortex. We have investigated the effects of spermine oxidase overexpression in the mouse neocortex by transcript accumulation, immunohistochemical analysis, enzymatic assays and polyamine content in young and aged animals. Transgenic JoSMOrec mice showed in the neocortex a higher H2O2 production in respect to Wild-Type controls, indicating an increase of oxidative stress due to SMO overexpression. Moreover, the response of transgenic mice to excitotoxic brain injury, induced by kainic acid injection, was evaluated by analysing the behavioural phenotype, the immunodistribution of neural cell populations, and the ultrastructural features of neocortical neurons. Spermine oxidase overexpression and the consequently altered polyamine levels in the neocortex affects the cytoarchitecture in the adult and aging brain, as well as after neurotoxic insult. It resulted that the transgenic JoSMOrec mouse line is more sensitive to KA than Wild-Type mice, indicating an important role of spermine oxidase during excitotoxicity. These results provide novel evidences of the complex and critical functions carried out by spermine oxidase and spermine in the mammalian brain.
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Affiliation(s)
| | | | - Marcello D'Amelio
- Laboratory of Molecular Neuroembryology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Fondazione Santa Lucia, Rome, Italy
| | - Virve Cavallucci
- Laboratory of Molecular Neuroembryology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Fondazione Santa Lucia, Rome, Italy
| | - Sandra Moreno
- Dipartimento di Biologia, Università “Roma Tre,” Rome, Italy
| | - Joachim Berger
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Australia
| | - Roberta Nardacci
- Istituto Nazionale per le Malattie Infettive, IRCCS “L. Spallanzani,” Rome, Italy
| | - Manuela Marcoli
- Dipartimento di Farmacia, Sez. Farmacologia e Tossicologia, Centro di Eccellenza per la Ricerca Biomedica CEBR, Università di Genova, Genoa, Italy
| | - Guido Maura
- Dipartimento di Farmacia, Sez. Farmacologia e Tossicologia, Centro di Eccellenza per la Ricerca Biomedica CEBR, Università di Genova, Genoa, Italy
| | - Mauro Piacentini
- Istituto Nazionale per le Malattie Infettive, IRCCS “L. Spallanzani,” Rome, Italy
| | - Roberto Amendola
- Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile (ENEA), Il Centro Ricerche Casaccia, Sezione Tossicologia e Scienze Biomediche (BAS-BIOTECMED), Rome, Italy
| | - Francesco Cecconi
- Laboratory of Molecular Neuroembryology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Fondazione Santa Lucia, Rome, Italy
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Tan T, Xie J, Tong Z, Liu T, Chen X, Tian X. Repetitive transcranial magnetic stimulation increases excitability of hippocampal CA1 pyramidal neurons. Brain Res 2013; 1520:23-35. [PMID: 23651978 DOI: 10.1016/j.brainres.2013.04.053] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 04/18/2013] [Accepted: 04/29/2013] [Indexed: 12/11/2022]
Abstract
Repetitive transcranial magnetic stimulation (rTMS) is able to induce alteration in cortical activity and excitability that outlast the period of stimulation, which is long-term depre-ssion (LTD) or long-term potentiation (LTP)-like. Accumulating evidence shows that Na(+), Ca(2+) and K(+) channels are important for the regulation of neuronal excitability. To investigate the possible mechanisms of rTMS on regulation of intrinsic excitability in hippocampal neurons, the male or female Sprague-Dawley rats aged 2-3 d or 7-8 d were treated with 14 or 7-d's low frequency (1 Hz) rTMS (400 stimuli/d), respectively. After that, the effects of rTMS on ion channels such as Na(+)-channel, A-type K(+)-channel and Ca(2+)-channel in rat hippocampal CA1 pyramidal neurons were performed by standard whole-cell patch-clamp technique. The results showed that the peak amplitude and maximal rise slope of evoked single action potential (AP) were significantly increased after 14-d's rTMS treatment. Meanwhile, the AP threshold was significantly more depolarized in neurons after 14-d's rTMS treatment than neurons in control group that without rTMS treatment. The spontaneous excitatory post-synaptic currents (sEPSCs) frequency and amplitude of CA1 pyramidal neurons in groups with rTMS treatment (both 7 d and 14 d) were obviously increased compared with the age-matched control group. Furthermore, we found that electrophysiological properties of Na(+)-channel were markedly changed after rTMS treatment, including negative-shifted activation and inactivation curves, as well as fasten recovery rate. After rTMS application, the IA amplitude of K(+)-channel was reduced; the activation and inactivation curves of K(+)-channel were significantly shifted to right. Time constant of recovery from inactivation was also more rapid. Moreover, rTMS induced an obvious increment in the maximal current peak amplitude of Ca(2+)-channel. At the same time, there was a significant rightward shift in the activation curve and inactivation curves of Ca(2+)-channel. These data suggest that rTMS can enhance the AP and sEPSCs of hippocampal CA1 neurons. Altered electrophysiological properties of Na(+)-channel, A-type K(+) channels and Ca(2+) channels contribute to the underling mechanisms of rTMS-induced up-regulation of neural excitability.
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Affiliation(s)
- Tao Tan
- School of Biomedical Engineering, Tianjin Medical University, Tianjin 300070, China.
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45
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Inward-rectifying potassium (Kir) channels regulate pacemaker activity in spinal nociceptive circuits during early life. J Neurosci 2013; 33:3352-62. [PMID: 23426663 DOI: 10.1523/jneurosci.4365-12.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Pacemaker neurons in neonatal spinal nociceptive circuits generate intrinsic burst firing and are distinguished by a lower "leak" membrane conductance compared with adjacent nonbursting neurons. However, little is known about which subtypes of leak channels regulate the level of pacemaker activity within the developing rat superficial dorsal horn (SDH). Here we demonstrate that a hallmark feature of lamina I pacemaker neurons is a reduced conductance through inward-rectifying potassium (K(ir)) channels at physiological membrane potentials. Differences in the strength of inward rectification between pacemakers and nonpacemakers indicate the presence of functionally distinct K(ir) currents in these two populations at room temperature. However, K(ir) currents in both groups showed high sensitivity to block by extracellular Ba²⁺ (IC₅₀ ~ 10 μm), which suggests the presence of "classical" K(ir) (K(ir)2.x) channels in the neonatal SDH. The reduced K(ir) conductance within pacemakers is unlikely to be explained by an absence of particular K(ir)2.x isoforms, as immunohistochemical analysis revealed the expression of K(ir)2.1, K(ir)2.2, and K(ir)2.3 within spontaneously bursting neurons. Importantly, Ba²⁺ application unmasked rhythmic burst firing in ∼42% of nonbursting lamina I neurons, suggesting that pacemaker activity is a latent property of a sizeable population of SDH cells during early life. In addition, the prevalence of spontaneous burst firing within lamina I was enhanced in the presence of high internal concentrations of free Mg²⁺, consistent with its documented ability to block K(ir) channels from the intracellular side. Collectively, the results indicate that K(ir) channels are key modulators of pacemaker activity in newborn central pain networks.
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46
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Fritz E, Izaurieta P, Weiss A, Mir FR, Rojas P, Gonzalez D, Rojas F, Brown RH, Madrid R, van Zundert B. Mutant SOD1-expressing astrocytes release toxic factors that trigger motoneuron death by inducing hyperexcitability. J Neurophysiol 2013; 109:2803-14. [PMID: 23486205 DOI: 10.1152/jn.00500.2012] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating paralytic disorder caused by dysfunction and degeneration of motoneurons starting in adulthood. Recent studies using cell or animal models document that astrocytes expressing disease-causing mutations of human superoxide dismutase 1 (hSOD1) contribute to the pathogenesis of ALS by releasing a neurotoxic factor(s). Neither the mechanism by which this neurotoxic factor induces motoneuron death nor its cellular site of action has been elucidated. Here we show that acute exposure of primary wild-type spinal cord cultures to conditioned medium derived from astrocytes expressing mutant SOD1 (ACM-hSOD1(G93A)) increases persistent sodium inward currents (PC(Na)), repetitive firing, and intracellular calcium transients, leading to specific motoneuron death days later. In contrast to TTX, which paradoxically increased twofold the amplitude of calcium transients and killed motoneurons, reduction of hyperexcitability by other specific (mexiletine) and nonspecific (spermidine and riluzole) blockers of voltage-sensitive sodium (Na(v)) channels restored basal calcium transients and prevented motoneuron death induced by ACM-hSOD1(G93A). These findings suggest that riluzole, the only FDA-approved drug with known benefits for ALS patients, acts by inhibiting hyperexcitability. Together, our data document that a critical element mediating the non-cell-autonomous toxicity of ACM-hSOD1(G93A) on motoneurons is increased excitability, an observation with direct implications for therapy of ALS.
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Affiliation(s)
- Elsa Fritz
- Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andres Bello, Ave Republica 217, Santiago, Chile
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Colombo E, Franceschetti S, Avanzini G, Mantegazza M. Phenytoin inhibits the persistent sodium current in neocortical neurons by modifying its inactivation properties. PLoS One 2013; 8:e55329. [PMID: 23383157 PMCID: PMC3558486 DOI: 10.1371/journal.pone.0055329] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 12/20/2012] [Indexed: 12/13/2022] Open
Abstract
The persistent Na+ current (INaP) is important for neuronal functions and can play a role in several pathologies, although it is small compared to the transient Na+ current (INaT). Notably, INaP is not a real persistent current because it undergoes inactivation with kinetics in the order of tens of seconds, but this property has often been overlooked. Na+ channel blockers, drugs used for treating epilepsy and other diseases, can inhibit INaP, but the mechanism of this action and the conditions in which INaP can be actually inhibited have not been completely clarified yet. We evaluated the action of phenytoin (PHT), a prototype anti-epileptic Na+ channel blocker, on INaP inactivation in pyramidal neurons of rat sensorimotor cortical slices at different concentrations, from 5 to 100 µM. PHT did not modify INaP evoked with depolarizing voltage ramps of 50 or 100 mVs−1, but decreased INaP evoked by slower voltage ramps (10 mVs−1). However, at all of the tested concentrations, PHT decreased INaP evoked by faster ramps when they were preceded by inactivating pre-pulses. Moreover, PHT shifted towards negative potentials the voltage-dependence of INaP inactivation and accelerated its kinetics of development also at depolarized potentials (+40 mV), not consistently with a simple inactivated state stabilizer. Therefore, our study shows a prominent PHT effect on INaP inactivation rather than an open channel block, which is instead often implied. INaP is inhibited by PHT only in conditions that induce major INaP inactivation. These results highlight the importance of INaP inactivation not only for physiological functions but also as drug target, which could be shared by other therapeutic drugs. Through this action PHT can reduce INaP-induced long-lasting pathological depolarisations and intracellular sodium overload, whereas shorter INaP actions should not be modified. These properties set the conditions of efficacy and the limits of PHT as INaP inhibitor.
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Affiliation(s)
- Elisa Colombo
- Department of Neurophysiopathology – Epilepsy Center, Foundation IRCCS Neurological Institute C. Besta, Milan, Italy
| | - Silvana Franceschetti
- Department of Neurophysiopathology – Epilepsy Center, Foundation IRCCS Neurological Institute C. Besta, Milan, Italy
| | - Giuliano Avanzini
- Department of Neurophysiopathology – Epilepsy Center, Foundation IRCCS Neurological Institute C. Besta, Milan, Italy
| | - Massimo Mantegazza
- Department of Neurophysiopathology – Epilepsy Center, Foundation IRCCS Neurological Institute C. Besta, Milan, Italy
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), CNRS UMR7275 and University of Nice-Sophia Antipolis, Valbonne, France
- * E-mail:
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Spatial mismatch between the Na+ flux and spike initiation in axon initial segment. Proc Natl Acad Sci U S A 2013; 110:4051-6. [PMID: 23341597 DOI: 10.1073/pnas.1215125110] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It is widely believed that, in cortical pyramidal cells, action potentials (APs) initiate in the distal portion of axon initial segment (AIS) because that is where Na(+) channel density is highest. To investigate the relationship between the density of Na(+) channels and the spatiotemporal pattern of AP initiation, we simultaneously recorded Na(+) flux and action currents along the proximal axonal length. We found that functional Na(+) channel density is approximately four times lower in the AP trigger zone than in the middle of the AIS, where it is highest. Computational analysis of AP initiation revealed a paradoxical mismatch between the AP threshold and Na(+) channel density, which could be explained by the lopsided capacitive load imposed on the proximal end of the AIS by the somatodendritic compartment. Favorable conditions for AP initiation are therefore achieved in the distal AIS portion, close to the edge of myelin, where the current source-load ratio is highest. Our findings suggest that cable properties play a central role in determining where the AP starts, such that small plastic changes in the local AIS Na(+) channel density could have a large influence on neuronal excitability as a whole.
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Structural insight into DFMO resistant ornithine decarboxylase from Entamoeba histolytica: an inkling to adaptive evolution. PLoS One 2013; 8:e53397. [PMID: 23326423 PMCID: PMC3543441 DOI: 10.1371/journal.pone.0053397] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 11/28/2012] [Indexed: 11/19/2022] Open
Abstract
Background Polyamine biosynthetic pathway is a validated therapeutic target for large number of infectious diseases including cancer, giardiasis and African sleeping sickness, etc. α-Difluoromethylornithine (DFMO), a potent drug used for the treatment of African sleeping sickness is an irreversible inhibitor of ornithine decarboxylase (ODC), the first rate limiting enzyme of polyamine biosynthesis. The enzyme ODC of E. histolytica (EhODC) has been reported to exhibit resistance towards DFMO. Methodology/Principal Finding The basis for insensitivity towards DFMO was investigated by structural analysis of EhODC and conformational modifications at the active site. Here, we report cloning, purification and crystal structure determination of C-terminal truncated Entamoeba histolytica ornithine decarboxylase (EhODCΔ15). Structure was determined by molecular replacement method and refined to 2.8 Å resolution. The orthorhombic crystal exhibits P212121 symmetry with unit cell parameters a = 76.66, b = 119.28, c = 179.28 Å. Functional as well as evolutionary relations of EhODC with other ODC homologs were predicted on the basis of sequence analysis, phylogeny and structure. Conclusions/Significance We determined the tetrameric crystal structure of EhODCΔ15, which exists as a dimer in solution. Insensitivity towards DFMO is due to substitution of key substrate binding residues in active site pocket. Additionally, a few more substitutions similar to antizyme inhibitor (AZI), a non-functional homologue of ODCs, were identified in the active site. Here, we establish the fact that EhODC sequence has conserved PLP binding residues; in contrast few substrate binding residues are mutated similar to AZI. Further sequence analysis and structural studies revealed that EhODC may represent as an evolutionary bridge between active decarboxylase and inactive AZI.
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Angelucci E, Moreno S, D’Amelio M, Nardacci R, Cecconi F, Mariottini P, Cervelli M. A new transgenic mouse model for studying the neurotoxicity of spermine oxidase dosage in the response to excitotoxic injury. Mol Neurodegener 2013. [PMCID: PMC3847096 DOI: 10.1186/1750-1326-8-s1-p4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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