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Belo do Nascimento I, Damblon J, Ingelbrecht C, Goursaud S, Massart M, Dumont A, Desmet N, Hermans E. Pharmacological evidence for the concept of spare glutamate transporters. Neurochem Int 2021; 149:105142. [PMID: 34314789 DOI: 10.1016/j.neuint.2021.105142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/09/2021] [Accepted: 07/22/2021] [Indexed: 01/30/2023]
Abstract
Through the efficient clearance of extracellular glutamate, high affinity astrocytic glutamate transporters constantly shape excitatory neurotransmission in terms of duration and spreading. Even though the glutamate transporter GLT-1 (also known as EAAT2/SLC1A2) is amongst the most abundant proteins in the mammalian brain, its density and activity are tightly regulated. In order to study the influence of changes in the expression of GLT-1 on glutamate uptake capacity, we have developed a model in HEK cells where the density of the transporter can be manipulated thanks to a tetracycline-inducible promoter. Exposing the cells to doxycycline concentration-dependently increased GLT-1 expression and substrate uptake velocity. However, beyond a certain level of induction, increasing the density of transporters at the cell surface failed to increase the maximal uptake. This suggested the progressive generation of a pool of spare transporters, a hypothesis that was further validated using the selective GLT-1 blocker WAY-213613 of which potency was influenced by the density of the transporters. The curve showing inhibition of uptake by increasing concentrations of WAY-213613 was indeed progressively rightward shifted when tested in cells where the transporter density was robustly induced. As largely documented in the context of cell-surface receptors, the existence of 'spare' glutamate transporters in the nervous tissue and particularly in astrocytes could impact on the consequences of physiological or pathological regulation of these transporters.
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Affiliation(s)
- Inês Belo do Nascimento
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, 1200, Brussels, Belgium
| | - Jonathan Damblon
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, 1200, Brussels, Belgium
| | - Caroline Ingelbrecht
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, 1200, Brussels, Belgium
| | - Stéphanie Goursaud
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, 1200, Brussels, Belgium
| | - Marion Massart
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, 1200, Brussels, Belgium
| | - Amélie Dumont
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, 1200, Brussels, Belgium
| | - Nathalie Desmet
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, 1200, Brussels, Belgium
| | - Emmanuel Hermans
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, 1200, Brussels, Belgium.
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Laureys G, Gerlo S, Spooren A, Demol F, De Keyser J, Aerts JL. β₂-adrenergic agonists modulate TNF-α induced astrocytic inflammatory gene expression and brain inflammatory cell populations. J Neuroinflammation 2014; 11:21. [PMID: 24479486 PMCID: PMC3942172 DOI: 10.1186/1742-2094-11-21] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Accepted: 01/15/2014] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The NF-κB signaling pathway orchestrates many of the intricate aspects of neuroinflammation. Astrocytic β₂-adrenergic receptors have emerged as potential regulators in central nervous system inflammation and are potential targets for pharmacological modulation. The aim of this study was to elucidate the crosstalk between astrocytic β₂-adrenergic receptors and the TNF-α induced inflammatory gene program. METHODS Proinflammatory conditions were generated by the administration of TNF-α. Genes that are susceptible to astrocytic crosstalk between β₂-adrenergic receptors (stimulated by clenbuterol) and TNF-α were identified by qPCR-macroarray-based gene expression analysis in a human 1321 N1 astrocytoma cell line. Transcriptional patterns of the identified genes in vitro were validated by RT-PCR on the 1321 N1 cell line as well as on primary rat astrocytes. In vivo expression patterns were examined by intracerebroventricular administration of clenbuterol and/or TNF-α in rats. To examine the impact on the inflammatory cell content of the brain we performed extensive FACS analysis of rat brain immune cells after intracerebroventricular clenbuterol and/or TNF-α administration. RESULTS Parallel transcriptional patterns in vivo and in vitro confirmed the relevance of astrocytic β₂-adrenergic receptors as modulators of brain inflammatory responses. Importantly, we observed pronounced effects of β2-adrenergic receptor agonists and TNF-α on IL-6, CXCL2, CXCL3, VCAM1, and ICAM1 expression, suggesting a role in inflammatory brain cell homeostasis. Extensive FACS-analysis of inflammatory cell content in the brain demonstrated that clenbuterol/TNF-α co-administration skewed the T cell population towards a double negative phenotype and induced a shift in the myeloid brain cell population towards a neutrophilic predominance. CONCLUSIONS Our results show that astrocytic β₂-adrenergic receptors are potent regulators of astrocytic TNF-α-activated genes in vitro and in vivo, and ultimately modulate the molecular network involved in the homeostasis of inflammatory cells in the central nervous system. Astrocytic β₂-adrenergic receptors and their downstream signaling pathway may serve as potential targets to modulate neuroinflammatory responses.
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Affiliation(s)
- Guy Laureys
- Department of Neurology, University Hospital Brussels, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium
| | - Sarah Gerlo
- VIB Department of Medical Protein Research, Ghent University Department of Biochemistry (Faculty of Medicine and Health Sciences), Albert Baertsoenkaai 3, 9000 Ghent, Belgium
| | - Anneleen Spooren
- Department of Physiology, Laboratory of Eukaryotic Gene Expression and Signal Transduction, Ghent University, Proeftuinstraat 86, 9000 Ghent, Belgium
| | - Frauke Demol
- Department of Neurology, University Hospital Brussels, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium
| | - Jacques De Keyser
- Department of Neurology, University Hospital Brussels, Center for Neurosciences, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium
- Department of Neurology, University Medical Center Groningen, RUG, Hanzeplein 1, 9713 GZ Groningen, the Netherlands
| | - Joeri L Aerts
- Laboratory of Molecular and Cellular Therapy, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
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Goursaud S, Focant MC, Berger JV, Nizet Y, Maloteaux J, Hermans E. The VPAC
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agonist peptide histidine isoleucine (PHI) up‐regulates glutamate transport in the corpus callosum of a rat model of amyotrophic lateral sclerosis (hSOD1
G93A
) by inhibiting caspase‐3 mediated inactivation of GLT‐1a. FASEB J 2011; 25:3674-86. [DOI: 10.1096/fj.11-182337] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Stéphanie Goursaud
- Group of Neuropharmacology, Institute of NeuroscienceUniversité Catholique de Louvain Brussels Belgium
| | - Marylène C. Focant
- Group of Neuropharmacology, Institute of NeuroscienceUniversité Catholique de Louvain Brussels Belgium
| | - Julie V. Berger
- Group of Neuropharmacology, Institute of NeuroscienceUniversité Catholique de Louvain Brussels Belgium
| | - Yannick Nizet
- Laboratory of Experimental SurgeryInstitute of Experimental and Clinical Research, Université Catholique de Louvain Brussels Belgium
| | - Jean‐Marie Maloteaux
- Group of Neuropharmacology, Institute of NeuroscienceUniversité Catholique de Louvain Brussels Belgium
| | - Emmanuel Hermans
- Group of Neuropharmacology, Institute of NeuroscienceUniversité Catholique de Louvain Brussels Belgium
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Differential regulation of vasoactive intestinal peptide (VIP) in the dentate gyrus and hippocampus via the NO-cGMP pathway following kainic acid-induced seizure in the rat. J Mol Neurosci 2010; 42:359-69. [PMID: 20369387 DOI: 10.1007/s12031-010-9353-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Accepted: 03/12/2010] [Indexed: 12/14/2022]
Abstract
We have previously shown that kainic acid (KA) increases nitric oxide (NO) synthase (NOS) production in the rat dentate gyrus (DG) and hippocampus (CA3), and NOS inhibition [(by N(G)-nitro-L-arginine methylester (L-NAME)] modulates the vasoactive intestinal peptide (VIP)-responsive gene, activity-dependent neuroprotective protein, and alters neuro- and astrogliogenesis (Cosgrave et al. in Neurobiol Dis 30(3):281-292 2008, J Mol Neurosci 39(1-2):9-21, 2009, 2010). In the present study, using the same model we demonstrate that VIP synthesis is differentially regulated by the NO-cyclic guanosine monophosphate (cGMP) pathway in the DG and CA3 at 3 h and 3 days post-KA. At 3 h post-KA: In L-NAME+KA/7-nitroindazole (7-NI)+KA, stratum granulosum (SG) and subgranular zone (SGZ) cells were intensely stained for VIP when compared with L-NAME/7-NI/KA alone. Soluble guanylyl cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, blocks cGMP production), suppressed astrocytic activation (glial fibrillary acidic protein) but other cell types were VIP(+); however, ODQ+KA suppressed overall VIP synthesis in the DG. At 3 days post-KA: In L-NAME+KA/7-NI+KA, SGZ and SG cells continued to express VIP, while in the KA alone, only SGZ cells were VIP(+). ODQ increased VIP(+) cells in the SG, and in contrast to 3 h, VIP-containing nNOS(+) cells increased in ODQ+KA when compared to vehicle+KA. In the hippocampus, 7-NI/ODQ had no effect on VIP at 3 h/3 days, while L-NAME+KA at 3 days increased VIP(+) cells, but reduced VIP-like immunoreactivity in astrocytes. These results suggest that the NO-cGMP pathway differentially regulates VIP in the DG and hippocampus during seizure.
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Yang K, Trepanier CH, Li H, Beazely MA, Lerner EA, Jackson MF, MacDonald JF. Vasoactive intestinal peptide acts via multiple signal pathways to regulate hippocampal NMDA receptors and synaptic transmission. Hippocampus 2009; 19:779-89. [PMID: 19173226 DOI: 10.1002/hipo.20559] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Vasoactive intestinal peptide (VIP) is a 28-amino acid peptide, which belongs to a superfamily of structurally related peptide hormones including pituitary adenylate cyclase-activating polypeptide (PACAP). Although several studies have identified the involvement of PACAP in learning and memory, little work has been done to investigate such a role for VIP. At least three receptors for VIP have been identified including the PACAP receptor (PAC1-R) and the two VIP receptors (VPAC receptors). VIP can activate the PAC1-R only if it is used at relatively high concentrations (e.g., 100 nM); however, at lower concentrations (e.g., 1 nM) it is selective for the VPAC receptors. Our lab has showed that PAC1-R activation signals through PKC/CAKbeta/Src pathway to regulate NMDA receptors; however, there is little known about the potential regulation of NMDA receptors by VPAC receptors. Our studies demonstrated that application of 1 nM VIP enhanced NMDA currents by stimulating the VPAC receptors as the effect was blocked by VPAC receptor antagonist [Ac-Tyr(1), D-Phe(2)]GRF (1-29). This enhancement of NMDA currents was blocked by both Rp-cAMPS and PKI(14-22) (they are highly specific PKA inhibitors), but not by the specific PKC inhibitor, bisindolylmaleimide I. In addition, the VIP-induced enhancement of NMDA currents was accentuated by inhibition of phosphodiesterase 4, which inhibits the degradation of cAMP. This regulation of NMDA receptors also required the scaffolding protein AKAP. In contrast, the potentiation induced by high concentration of VIP (e.g., 100 nM) was mediated by PAC1-R as well as by Src kinase. Overall, these results show that VIP can regulate NMDA receptors through different receptors and signaling pathways.
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Affiliation(s)
- Kai Yang
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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Vaudry D, Falluel-Morel A, Bourgault S, Basille M, Burel D, Wurtz O, Fournier A, Chow BKC, Hashimoto H, Galas L, Vaudry H. Pituitary Adenylate Cyclase-Activating Polypeptide and Its Receptors: 20 Years after the Discovery. Pharmacol Rev 2009; 61:283-357. [DOI: 10.1124/pr.109.001370] [Citation(s) in RCA: 829] [Impact Index Per Article: 55.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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Marpegan L, Krall TJ, Herzog ED. Vasoactive intestinal polypeptide entrains circadian rhythms in astrocytes. J Biol Rhythms 2009; 24:135-43. [PMID: 19346450 DOI: 10.1177/0748730409332042] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Many mammalian cell types show daily rhythms in gene expression driven by a circadian pacemaker. For example, cultured astrocytes display circadian rhythms in Period1 and Period2 expression. It is not known, however, how or which intercellular factors synchronize and sustain rhythmicity in astrocytes. Because astrocytes are highly sensitive to vasoactive intestinal polypeptide (VIP), a neuropeptide released by neurons and important for the coordination of daily cycling, the authors hypothesized that VIP entrains circadian rhythms in astrocytes. They used astrocyte cultures derived from knock-in mice containing a bioluminescent reporter of PERIOD2 (PER2) protein, to assess the effects of VIP on the rhythmic properties of astrocytes. VIP induced a dose-dependent increase in the peak-to-trough amplitude of the ensemble rhythms of PER2 expression with maximal effects near 100 nM VIP and threshold values between 0.1 and 1 nM. VIP also induced dose- and phase-dependent shifts in PER2 rhythms and daily VIP administration entrained bioluminescence rhythms of astrocytes to a predicted phase angle. This is the first demonstration that a neuropeptide can entrain glial cells to a phase predicted by a phase-response curve. The authors conclude that VIP potently entrains astrocytes in vitro and is a candidate for coordinating daily rhythms among glia in the brain.
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Affiliation(s)
- Luciano Marpegan
- Department of Biology, Washington University, St. Louis, Missouri 63130-4899, USA
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Goursaud S, Maloteaux JM, Hermans E. Distinct expression and regulation of the glutamate transporter isoforms GLT-1a and GLT-1b in cultured astrocytes from a rat model of amyotrophic lateral sclerosis (hSOD1G93A). Neurochem Int 2009; 55:28-34. [PMID: 19428804 DOI: 10.1016/j.neuint.2009.02.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Revised: 02/10/2009] [Accepted: 02/12/2009] [Indexed: 12/14/2022]
Abstract
Impaired glutamate uptake associated with accumulation of extracellular glutamate is a well-documented feature of amyotrophic lateral sclerosis (ALS) and related excitotoxicity is frequently proposed to participate in the progression of the disease. We herein characterised the expression and activity of the glutamate transporter glutamate transporter 1 (GLT-1) in cultured cortical astrocytes derived from a transgenic rat strain expressing an ALS-related mutated form of human superoxide dismutase 1 (hSOD1(G93A)). Measurements of d-[(3)H]-aspartate uptake velocity in the presence of selective glutamate transporter blockers demonstrated that astrocytes from the transgenic rats showed an impaired GLT-1 activity as compared to cells from wild-type animals. In addition, the density of GLT-1a mRNA in cells from hSOD1(G93A) animals appeared nearly 2-fold lower while the density of GLT-1b mRNA was nearly 2-fold higher. Besides, we observed that exposing the astrocytes from hSOD1(G93A) rats to the neuroprotective transmitter Peptide Histidine Isoleucine (PHI) for 24h caused a 4.5-fold increase in the GLT-1b mRNA level without influencing the expression of the other key isoform GLT-1a. This selective upregulation of GLT-1b by the neuropeptide was correlated with a significant increase in d-[(3)H]-aspartate uptake activity. The possibility to specifically regulate a single isoform of the high-affinity transporter GLT-1 is an unprecedented observation which sheds light on new perspectives for the pharmacological manipulation of glutamate transmission in diseases such as ALS.
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Affiliation(s)
- Stéphanie Goursaud
- Laboratoire de Pharmacologie Expérimentale, Université catholique de Louvain, Brussels, Belgium
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Goursaud S, Kozlova EN, Maloteaux JM, Hermans E. Cultured astrocytes derived from corpus callosum or cortical grey matter show distinct glutamate handling properties. J Neurochem 2009; 108:1442-52. [PMID: 19222709 DOI: 10.1111/j.1471-4159.2009.05889.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
While the astrocytic control of extracellular glutamate concentration at synaptic contacts is well characterized, little is known regarding the clearance of glutamate along axon tracts, even though local excitotoxic damage has been reported. Therefore, we have compared glutamate handling in astrocyte cultures derived from white matter (corpus callosum) and grey matter tissues (cortical structures). These populations of astrocytes showed clearly distinct phenotypes, adopting stellate or protoplasmic morphologies respectively. In addition, white matter astrocytes showed high densities of the intermediate filament proteins glial fibrillary acidic protein, vimentin and nestin. The glutamate-aspartate transporter and glutamate transporter-1, as well as glutamine synthetase, were found to be expressed at higher levels in white matter compared with grey matter astrocytes. Consistent with this aspartate uptake capacity was three to fourfold higher in white matter cells, and the use of specific inhibitors revealed a substantial activity of glutamate transporter-1, contrasting with grey matter cells where this transporter appeared poorly functional. In addition, expression of type 5 metabotropic glutamate receptors was considerably higher in white matter astrocytes where the agonist (S)-3,5-dihydroxyphenylglycine triggered a large release of intracellular calcium. Differences in these astrocyte cultures were also observed when exposed to experimental conditions that trigger glial activation. This study highlights typical features of cultured astrocytes derived from white matter tissues, which appear constitutively adapted to handle excitotoxic insults. Moreover, the expression and activity of the astroglial components involved in the control of glutamatergic transmission are reinforced when these cells are maintained under conditions mimicking a gliotic environment.
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Affiliation(s)
- Stéphanie Goursaud
- Laboratoire de Pharmacologie Expérimentale, Université catholique de Louvain, Brussels, Belgium
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Matsumoto S, Arakawa Y, Ohishi M, Yanaihara H, Iwanaga T, Kurokawa N. Suppressive action of pituitary adenylate cyclase activating polypeptide (PACAP) on proliferation of immature mouse Leydig cell line TM3 cells. ACTA ACUST UNITED AC 2009; 29:321-30. [PMID: 19129676 DOI: 10.2220/biomedres.29.321] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We aimed in the current study to understand the participation of PACAP in stage-specific Leydig and Sertoli cell functions. For this purpose, clonal cell lines TM3 (Leydig) and TM4 (Sertoli) cells, derived from the testis of immature BALB/c mice, were used. PACAP-specific receptors were detected in TM3 cells, but not in TM4 cells, which were characterized as PAC1 (type I) receptors. Stimulation of cAMP accumulation and testosterone secretion were observed in TM3 cells during 1-2 h treatment with PACAP38 (10(-10)-10(-7) M) or PACAP27 (10(-11)-10(-7) M). After around 10 h treatment with 10(-11)-10(-7) M PACAP38 or PACAP27, proliferation of TM3 cells was suppressed in time- and dose-dependent manners, which was confirmed by real-time cell electronic sensing (RT-CES) system and phase-contrast microscopy. At 6 h after the addition of PACAP38, the percent cell population in G(2)/M phases increased significantly, while that in S phase showed significant decrease with little change in G(0)/G(1) phases. The results revealed that PACAP exerts, in addition to early stimulatory effect on cAMP formation-steroidogenesis, sustained suppressive effect on cell proliferation in TM3 cells by controlling progression of the cell cycle. The suppressive action of PACAP on proliferation in TM3 cells supports the stage-specific participation of the peptide in differentiation of immature mouse Leydig cells.
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Affiliation(s)
- Shoji Matsumoto
- Laboratory of Pharmaceutical Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
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