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Castagnola S, Delhaye S, Folci A, Paquet A, Brau F, Duprat F, Jarjat M, Grossi M, Béal M, Martin S, Mantegazza M, Bardoni B, Maurin T. New Insights Into the Role of Ca v2 Protein Family in Calcium Flux Deregulation in Fmr1-KO Neurons. Front Mol Neurosci 2018; 11:342. [PMID: 30319351 PMCID: PMC6170614 DOI: 10.3389/fnmol.2018.00342] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 08/30/2018] [Indexed: 12/31/2022] Open
Abstract
Fragile X syndrome (FXS), the most common form of inherited intellectual disability (ID) and a leading cause of autism, results from the loss of expression of the Fmr1 gene which encodes the RNA-binding protein Fragile X Mental Retardation Protein (FMRP). Among the thousands mRNA targets of FMRP, numerous encode regulators of ion homeostasis. It has also been described that FMRP directly interacts with Ca2+ channels modulating their activity. Collectively these findings suggest that FMRP plays critical roles in Ca2+ homeostasis during nervous system development. We carried out a functional analysis of Ca2+ regulation using a calcium imaging approach in Fmr1-KO cultured neurons and we show that these cells display impaired steady state Ca2+ concentration and an altered entry of Ca2+ after KCl-triggered depolarization. Consistent with these data, we show that the protein product of the Cacna1a gene, the pore-forming subunit of the Cav2.1 channel, is less expressed at the plasma membrane of Fmr1-KO neurons compared to wild-type (WT). Thus, our findings point out the critical role that Cav2.1 plays in the altered Ca2+ flux in Fmr1-KO neurons, impacting Ca2+ homeostasis of these cells. Remarkably, we highlight a new phenotype of cultured Fmr1-KO neurons that can be considered a novel cellular biomarker and is amenable to small molecule screening and identification of new drugs to treat FXS.
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Affiliation(s)
- Sara Castagnola
- Université Côte d'Azur, CNRS UMR7275, IPMC, Valbonne, France.,CNRS LIA "Neogenex", Valbonne, France
| | - Sébastien Delhaye
- Université Côte d'Azur, CNRS UMR7275, IPMC, Valbonne, France.,CNRS LIA "Neogenex", Valbonne, France
| | | | - Agnès Paquet
- Université Côte d'Azur, CNRS UMR7275, IPMC, Valbonne, France
| | - Frédéric Brau
- Université Côte d'Azur, CNRS UMR7275, IPMC, Valbonne, France
| | - Fabrice Duprat
- Université Côte d'Azur, INSERM, CNRS UMR7275, IPMC, Valbonne, France
| | - Marielle Jarjat
- Université Côte d'Azur, CNRS UMR7275, IPMC, Valbonne, France.,CNRS LIA "Neogenex", Valbonne, France
| | - Mauro Grossi
- Université Côte d'Azur, CNRS UMR7275, IPMC, Valbonne, France.,CNRS LIA "Neogenex", Valbonne, France
| | - Méline Béal
- Université Côte d'Azur, CNRS UMR7275, IPMC, Valbonne, France.,CNRS LIA "Neogenex", Valbonne, France
| | - Stéphane Martin
- Université Côte d'Azur, INSERM, CNRS UMR7275, IPMC, Valbonne, France
| | | | - Barbara Bardoni
- CNRS LIA "Neogenex", Valbonne, France.,Université Côte d'Azur, INSERM, CNRS UMR7275, IPMC, Valbonne, France
| | - Thomas Maurin
- Université Côte d'Azur, CNRS UMR7275, IPMC, Valbonne, France.,CNRS LIA "Neogenex", Valbonne, France
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Moha ou Maati H, Widmann C, Gallois DSB, Heurteaux C, Borsotto M, Hugues M. Mapacalcine protects mouse neurons against hypoxia by blocking cell calcium overload. PLoS One 2013; 8:e66194. [PMID: 23843951 PMCID: PMC3699608 DOI: 10.1371/journal.pone.0066194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 05/07/2013] [Indexed: 12/01/2022] Open
Abstract
Stroke is one of a major cause of death and adult disability. Despite intense researches, treatment for stroke remains reduced to fibrinolysis, a technique useful for less than 10% of patients. Finding molecules able to treat or at least to decrease the deleterious consequences of stroke is an urgent need. Here, we showed that mapacalcine, a homodimeric peptide purified from the marine sponge Cliona vastifica, is able to protect mouse cortical neurons against hypoxia. We have also identified a subtype of L-type calcium channel as a target for mapacalcine and we showed that the channel has to be open for mapacalcine binding. The two main L-type subunits at the brain level are CaV1.3 and CaV1.2 subunits but mapacalcine was unable to block these calcium channels.Mapacalcine did not interfere with N-, P/Q- and R-type calcium channels. The protective effect was studied by measuring internal calcium level variation triggered by Oxygen Glucose Deprivation protocol, which mimics stroke, or glutamate stimulation. We showed that NMDA/AMPA receptors are not involved in the mapacalcine protection. The protective effect was confirmed by measuring the cell survival rate after Oxygen Glucose Deprivation condition. Our data indicate that mapacalcine is a promising molecule for stroke treatment.
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Affiliation(s)
- Hamid Moha ou Maati
- Institut de Pharmacologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique (UMR7275), Université de Nice Sophia Antipolis, Valbonne, France
| | - Catherine Widmann
- Institut de Pharmacologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique (UMR7275), Université de Nice Sophia Antipolis, Valbonne, France
| | - Djamila Sedjelmaci Bernard Gallois
- Institut de Pharmacologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique (UMR7275), Université de Nice Sophia Antipolis, Valbonne, France
| | - Catherine Heurteaux
- Institut de Pharmacologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique (UMR7275), Université de Nice Sophia Antipolis, Valbonne, France
| | - Marc Borsotto
- Institut de Pharmacologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique (UMR7275), Université de Nice Sophia Antipolis, Valbonne, France
- * E-mail: (MB); (MH)
| | - Michel Hugues
- Chimie Biologie des Membranes et des Nanoobjets, Centre National de la Recherche Scientifique (UMR5248), Pessac, France
- * E-mail: (MB); (MH)
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Jurkovičová-Tarabová B, Griesemer D, Pirone A, Sinnegger-Brauns MJ, Striessnig J, Friauf E. Repertoire of high voltage-activated Ca2+ channels in the lateral superior olive: functional analysis in wild-type, Cav1.3−/−, and Cav1.2DHP−/− mice. J Neurophysiol 2012; 108:365-79. [DOI: 10.1152/jn.00948.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Voltage-gated Ca2+ (Cav)1.3 α-subunits of high voltage-activated Ca2+ channels (HVACCs) are essential for Ca2+ influx and transmitter release in cochlear inner hair cells and therefore for signal transmission into the central auditory pathway. Their absence leads to deafness and to striking structural changes in the auditory brain stem, particularly in the lateral superior olive (LSO). Here, we analyzed the contribution of various types of HVACCs to the total Ca2+ current ( ICa) in developing mouse LSO neurons to address several questions: do LSO neurons express functional Cav1.3 channels? What other types of HVACCs are expressed? Are there developmental changes? Do LSO neurons of Cav1.3−/− mice show any compensatory responses, namely, upregulation of other HVACCs? Our electrophysiological and pharmacological results showed the presence of functional Cav1.3 and Cav1.2 channels at both postnatal days 4 and 12. Aside from these L-type channels, LSO neurons also expressed functional P/Q-type, N-type, and, most likely, R-type channels. The relative contribution of the four different subtypes to ICa appeared to be 45%, 29%, 22%, and 4% at postnatal day 12, respectively. The physiological results were flanked and extended by quantitative RT-PCR data. Altogether, LSO neurons displayed a broad repertoire of HVACC subtypes. Genetic ablation of Cav1.3 resulted in functional reorganization of some other HVACCs but did not restore normal ICa properties. Together, our results suggest that several types of HVACCs are of functional relevance for the developing LSO. Whether on-site loss of Cav1.3, i.e., in LSO neurons, contributes to the recently described malformation of the LSO needs to be determined by using tissue-specific Cav1.3−/− animals.
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Affiliation(s)
| | - Désirée Griesemer
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Antonella Pirone
- Institute of Physiology II and Department of Otolaryngology, Tübingen Hearing Research Centre, University of Tübingen, Tübingen, Germany; and
| | - Martina J. Sinnegger-Brauns
- Institute of Pharmacy, Pharmacology and Toxicology, Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Jörg Striessnig
- Institute of Pharmacy, Pharmacology and Toxicology, Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
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Bernstein GM, Jones OT. Kinetics of internalization and degradation of N-type voltage-gated calcium channels: Role of the α2/δ subunit. Cell Calcium 2007; 41:27-40. [PMID: 16759698 DOI: 10.1016/j.ceca.2006.04.010] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 04/22/2006] [Accepted: 04/24/2006] [Indexed: 11/27/2022]
Abstract
The contribution of voltage-gated calcium channels to excitable cell function depends, critically, upon the mechanisms that control their expression at the cell surface. While co-assembly of the pore forming alpha(1) and auxiliary beta subunits enhances channel surface expression, the levels are still only 30-40% of those seen with the core alpha(1B)/beta(1b)/alpha(2)delta calcium channel complex. To rationalize this observation, it has been suggested that the alpha(2)/delta subunit might stabilize calcium channel expression at the cell surface. To test this notion, we have resolved the effect of the alpha(2)/delta subunit on the rates of binding, internalization and degradation of defined N-type calcium channel surface complexes expressed in HEK293 cells, through pulse-labeling with the selective, cell impermeable, radioligand [(125)I]-omega-CgTx. Through detailed kinetic and sensitivity analysis we show that alpha(1B)/beta(1b)/alpha(2)delta complexes are internalized slowly (k(int) 0.4/h), whereupon, most become degraded (k(deg) 0.02/h). In contrast, alpha(1B)/beta(1b) complexes are internalized more rapidly (k(int) 0.8/h), following which they are either quickly degraded (k(deg) 0.1/h) or are sequestered slowly (k(tra) 0.1/h) to a pool that is metabolically stable within the time-frame of our experiments (24h). In neither case did we find evidence for recycling via the cell surface. Thus, our data argue for a novel mechanism where complexes lacking an alpha(2)/delta subunit are cleared from the cell surface and are rapidly degraded or stored, possibly for further attempts at complexation as new alpha(2)/delta subunits become available. The slower rate of internalization of complexes containing the alpha(2)/delta subunit rationalizes the stabilizing effect this subunit has upon calcium channel surface expression and suggests a mechanism by which alpha(2)delta mutations may cause severe neurological deficits.
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Affiliation(s)
- Geula M Bernstein
- Division of Cellular and Molecular Biology, Toronto Western Research Institute, University Health Network. 399 Bathurst Street, Toronto, Ontario, Canada
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