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Castro PA, Ramirez A, Sepúlveda FJ, Peters C, Fierro H, Waldron J, Luza S, Fuentealba J, Muñoz FJ, De Ferrari GV, Bush AI, Aguayo LG, Opazo CM. Copper-uptake is critical for the down regulation of synapsin and dynamin induced by neocuproine: modulation of synaptic activity in hippocampal neurons. Front Aging Neurosci 2014; 6:319. [PMID: 25520655 PMCID: PMC4253966 DOI: 10.3389/fnagi.2014.00319] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 10/30/2014] [Indexed: 01/08/2023] Open
Abstract
Extracellular and intracellular copper and zinc regulate synaptic activity and plasticity, which may impact brain functionality and human behavior. We have found that a metal coordinating molecule, Neocuproine, transiently increases free intracellular copper and zinc levels (i.e., min) in hippocampal neurons as monitored by Phen Green and FluoZin-3 fluorescence, respectively. The changes in free intracellular zinc induced by Neocuproine were abolished by the presence of a non-permeant copper chelator, Bathocuproine (BC), indicating that copper influx is needed for the action of Neocuproine on intracellular Zn levels. Moreover, Neocuproine decreased the mRNA levels of Synapsin and Dynamin, and did not affect the expression of Bassoon, tubulin or superoxide dismutase (SOD). Western blot analysis showed that protein levels of synapsin and dynamin were also down regulated in the presence of Neocuproine and that these changes were accompanied by a decrease in calcium transients and neuronal activity. Furthermore, Neocuproine decreased the number of active neurons, effect that was blocked by the presence of BC, indicating that copper influx is needed for the action of Neocuproine. We finally show that Neocuproine blocks the epileptiform-like activity induced by bicuculline in hippocampal neurons. Collectively, our data indicates that presynaptic protein configuration and function of primary hippocampal neurons is sensitive to transient changes in transition metal homeostasis. Therefore, small molecules able to coordinate transition metals and penetrate the blood-brain barrier might modify neurotransmission at the Central Nervous System (CNS). This might be useful to establish therapeutic approaches to control the neuronal hyperexcitabiltity observed in brain conditions that are associated to copper dyshomeotasis such as Alzheimer’s and Menkes diseases. Our work also opens a new avenue to find novel and effective antiepilepsy drugs based in metal coordinating molecules.
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Affiliation(s)
- Patricio A Castro
- Department of Physiology and Membrane Biology, Shriners Hospital for Children Northern California, University of California at Davis School of Medicine California, USA
| | - Alejandra Ramirez
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile ; Oxidation Biology Laboratory, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne Parkville, Melbourne, Victoria, Australia
| | - Fernando J Sepúlveda
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Christian Peters
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Humberto Fierro
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Javier Waldron
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Sandra Luza
- Oxidation Biology Laboratory, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne Parkville, Melbourne, Victoria, Australia
| | - Jorge Fuentealba
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Francisco J Muñoz
- Laboratory of Molecular Physiology and Channelopathies, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra Barcelona, Spain
| | - Giancarlo V De Ferrari
- Center for Biomedical Research and FONDAP Center for Genome Regulation, Universidad Andrés Bello Santiago, Chile
| | - Ashley I Bush
- Oxidation Biology Laboratory, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne Parkville, Melbourne, Victoria, Australia
| | - Luis G Aguayo
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Carlos M Opazo
- Oxidation Biology Laboratory, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne Parkville, Melbourne, Victoria, Australia
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Opazo CM, Greenough MA, Bush AI. Copper: from neurotransmission to neuroproteostasis. Front Aging Neurosci 2014; 6:143. [PMID: 25071552 PMCID: PMC4080678 DOI: 10.3389/fnagi.2014.00143] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 06/16/2014] [Indexed: 01/23/2023] Open
Abstract
Copper is critical for the Central Nervous System (CNS) development and function. In particular, different studies have shown the effect of copper at brain synapses, where it inhibits Long Term Potentation (LTP) and receptor pharmacology. Paradoxically, according to recent studies copper is required for a normal LTP response. Copper is released at the synaptic cleft, where it blocks glutamate receptors, which explain its blocking effects on excitatory neurotransmission. Our results indicate that copper also enhances neurotransmission through the accumulation of PSD95 protein, which increase the levels of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors located at the plasma membrane of the post-synaptic density. Thus, our findings represent a novel mechanism for the action of copper, which may have implications for the neurophysiology and neuropathology of the CNS. These data indicate that synaptic configuration is sensitive to transient changes in transition metal homeostasis. Our results suggest that copper increases GluA1 subunit levels of the AMPA receptor through the anchorage of AMPA receptors to the plasma membrane as a result of PSD-95 accumulation. Here, we will review the role of copper on neurotransmission of CNS neurons. In addition, we will discuss the potential mechanisms by which copper could modulate neuronal proteostasis (“neuroproteostasis”) in the CNS with focus in the Ubiquitin Proteasome System (UPS), which is particularly relevant to neurological disorders such as Alzheimer’s disease (AD) where copper and protein dyshomeostasis may contribute to neurodegeneration. An understanding of these mechanisms may ultimately lead to the development of novel therapeutic approaches to control metal and synaptic alterations observed in AD patients.
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Affiliation(s)
- Carlos M Opazo
- Oxidation Biology Laboratory, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne Melbourne, VIC, Australia
| | - Mark A Greenough
- Oxidation Biology Laboratory, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne Melbourne, VIC, Australia
| | - Ashley I Bush
- Oxidation Biology Laboratory, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne Melbourne, VIC, Australia
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Peters C, Fernandez-Perez EJ, Burgos CF, Espinoza MP, Castillo C, Urrutia JC, Streltsov VA, Opazo C, Aguayo LG. Inhibition of amyloid beta-induced synaptotoxicity by a pentapeptide derived from the glycine zipper region of the neurotoxic peptide. Neurobiol Aging 2013; 34:2805-14. [PMID: 23855983 DOI: 10.1016/j.neurobiolaging.2013.06.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 05/29/2013] [Accepted: 06/04/2013] [Indexed: 10/26/2022]
Abstract
A major characteristic of Alzheimer's disease is the presence of amyloid beta (Aβ) oligomers and aggregates in the brain. Aβ oligomers interact with the neuronal membrane inducing perforations, causing an influx of calcium ions and increasing the release of synaptic vesicles that leads to a delayed synaptic failure by vesicle depletion. Here, we identified a neuroprotective pentapeptide anti-Aβ compound having the sequence of the glycine zipper region of the C-terminal of Aβ (G33LMVG37). Docking and Förster resonance energy transfer experiments showed that G33LMVG37 interacts with Aβ at the C-terminal region, which is important for Aβ association and insertion into the lipid membrane. Furthermore, this pentapeptide interfered with Aβ aggregation, association, and perforation of the plasma membrane. The synaptotoxicity induced by Aβ after acute and chronic applications were abolished by G33LMVG37. These results provide a novel rationale for drug development against Alzheimer's disease.
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Affiliation(s)
- Christian Peters
- Laboratory of Neurophysiology, Department of Physiology, University of Concepción, Concepción, Chile; Laboratory of Neurobiometals, Department of Physiology, University of Concepción, Concepción, Chile
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Cooke RM, Luco S, Parker D. Manipulations of spinal cord excitability evoke developmentally-dependent compensatory changes in the lamprey spinal cord. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2012; 198:25-41. [DOI: 10.1007/s00359-011-0683-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 09/09/2011] [Accepted: 09/14/2011] [Indexed: 10/15/2022]
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Peters C, Muñoz B, Sepúlveda FJ, Urrutia J, Quiroz M, Luza S, De Ferrari GV, Aguayo LG, Opazo C. Biphasic effects of copper on neurotransmission in rat hippocampal neurons. J Neurochem 2011; 119:78-88. [PMID: 21824141 DOI: 10.1111/j.1471-4159.2011.07417.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The importance of copper in the CNS is well documented, but the mechanisms related to its brain functions are poorly understood. Copper is released at the synaptic cleft, where it may modulate neurotransmission. To understand the functional impact of copper on the neuronal network, we have analyzed the synaptic activity of primary rat hippocampal neurons by using different approaches including whole cell patch clamp, recording of calcium transients, immunofluorescence and western blot. Here, we show that copper produces biphasic changes in neurotransmission. When copper is acutely applied to the plate it blocks neurotransmission. Interestingly, when it is applied for 3 h to hippocampal neurons it mainly increases the frequency and amplitude of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)ergic currents (control: 0.21 ± 0.05 Hz/22.9 ± 1.3 pA; copper: 0.68 ± 0.16 Hz/30.5 ± 2.5 pA), intracellular calcium transients (control: 0.05 ± 0.013 Hz; copper: 0.11 ± 0.02 Hz) and evoked AMPA currents (control: EC50 8.3 ± 0.5 μM; copper: EC50 2.9 ± 0.2 μM). Moreover, our results suggest that copper increases GluA1 subunit levels of the AMPA receptor through the anchorage of AMPA receptors to the plasma membrane as a result of PSD-95 accumulation. We also found that copper-treated neurons displayed an undistinguishable neurotransmission to control neurons after 24 h of treatment, indicating that changes in neurotransmission induced by copper at 3 h of incubation are homeostatically regulated after long-term exposure to the metal. Together, our data reveal an unexpected biphasic effect of copper on neurotransmission, which may be relevant to understand the effects of this ion in brain diseases that display copper dyshomeostasis such as that observed in Alzheimer's disease (AD).
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Affiliation(s)
- Christian Peters
- Laboratorio de Neurobiometales Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
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Kim G, Kandler K. Synaptic changes underlying the strengthening of GABA/glycinergic connections in the developing lateral superior olive. Neuroscience 2010; 171:924-33. [PMID: 20888399 DOI: 10.1016/j.neuroscience.2010.09.054] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 09/22/2010] [Accepted: 09/24/2010] [Indexed: 10/19/2022]
Abstract
Before hearing onset, the topographic organization of the auditory GABA/glycinergic pathway from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO) is refined by synaptic silencing and strengthening. The synaptic mechanisms underlying the developmental strengthening of maintained MNTB-LSO connections are unknown. Here we address this question using whole-cell recordings from LSO neurons in slices prepared from prehearing mice. Minimal and maximal stimulation techniques demonstrated that during the first two postnatal weeks, individual LSO neurons lose about 55% of their initial presynaptic MNTB partners while maintained single-fiber connections become about 14-fold stronger. Analysis of MNTB-evoked miniature events indicates that this strengthening is accompanied by a 2-fold increase in quantal amplitude. Strengthening is not caused by an increase in the probability of release because paired pulse ratios (PPRs) increased from 0.7 in newborn animals to 0.9 around hearing onset, indicating a developmental decrease rather than increase in release probability. In addition, a possible soma-dendritic relocation of MNTB input seems unlikely to underlie their strengthening as indicated by analysis of the rise times of synaptic currents. Taken together, we conclude that the developmental strengthening of MNTB-LSO connections is achieved by a 2-fold increase in quantal size and an 8-fold increase in quantal content.
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Affiliation(s)
- G Kim
- Department of Otolaryngology, University of Pittsburgh School of Medicine, Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA
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Avila ME, Sepúlveda FJ, Burgos CF, Moraga-Cid G, Parodi J, Moon RT, Aguayo LG, Opazo C, De Ferrari GV. Canonical Wnt3a modulates intracellular calcium and enhances excitatory neurotransmission in hippocampal neurons. J Biol Chem 2010; 285:18939-47. [PMID: 20404321 PMCID: PMC2881816 DOI: 10.1074/jbc.m110.103028] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 04/16/2010] [Indexed: 11/06/2022] Open
Abstract
A role for Wnt signal transduction in the development and maintenance of brain structures is widely acknowledged. Recent studies have suggested that Wnt signaling may be essential for synaptic plasticity and neurotransmission. However, the direct effect of a Wnt protein on synaptic transmission had not been demonstrated. Here we show that nanomolar concentrations of purified Wnt3a protein rapidly increase the frequency of miniature excitatory synaptic currents in embryonic rat hippocampal neurons through a mechanism involving a fast influx of calcium from the extracellular space, induction of post-translational modifications on the machinery involved in vesicle exocytosis in the presynaptic terminal leading to spontaneous Ca(2+) transients. Our results identify the Wnt3a protein and a member of its complex receptor at the membrane, the low density lipoprotein receptor-related protein 6 (LRP6) coreceptor, as key molecules in neurotransmission modulation and suggest cross-talk between canonical and Wnt/Ca(2+) signaling in central neurons.
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Affiliation(s)
- Miguel E. Avila
- From the Departments of Biochemistry and Molecular Biology and
| | - Fernando J. Sepúlveda
- Physiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción P.O. Box 4070386, Chile
| | | | - Gustavo Moraga-Cid
- Physiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción P.O. Box 4070386, Chile
| | - Jorge Parodi
- Physiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción P.O. Box 4070386, Chile
| | - Randall T. Moon
- Howard Hughes Medical Institute, Department of Pharmacology and Institute for Stem Cell and Regenerative Medicine, University of Washington School of Medicine, Seattle, Washington 98195, and
| | - Luis G. Aguayo
- Physiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción P.O. Box 4070386, Chile
| | - Carlos Opazo
- Physiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción P.O. Box 4070386, Chile
| | - Giancarlo V. De Ferrari
- From the Departments of Biochemistry and Molecular Biology and
- the Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andrés Bello, Santiago P.O. Box 8370134, Chile
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Larrucea C, Castro P, Sepulveda FJ, Wandersleben G, Roa J, Aguayo LG. Sustained increase of Ca+2 oscillations after chronic TRPV1 receptor activation with capsaicin in cultured spinal neurons. Brain Res 2008; 1218:70-6. [DOI: 10.1016/j.brainres.2008.04.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 04/10/2008] [Accepted: 04/18/2008] [Indexed: 12/17/2022]
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Venard C, Boujedaini N, Belon P, Mensah-Nyagan A, Patte-Mensah C. Regulation of neurosteroid allopregnanolone biosynthesis in the rat spinal cord by glycine and the alkaloidal analogs strychnine and gelsemine. Neuroscience 2008; 153:154-61. [DOI: 10.1016/j.neuroscience.2008.02.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 02/11/2008] [Accepted: 02/11/2008] [Indexed: 11/15/2022]
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