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Fronczak KM, Li Y, Henchir J, Dixon CE, Carlson SW. Reductions in Synaptic Vesicle Glycoprotein 2 Isoforms in the Cortex and Hippocampus in a Rat Model of Traumatic Brain Injury. Mol Neurobiol 2021; 58:6006-6019. [PMID: 34435329 PMCID: PMC8602666 DOI: 10.1007/s12035-021-02534-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 08/15/2021] [Indexed: 11/25/2022]
Abstract
Traumatic brain injury (TBI) can produce lasting cognitive, emotional, and somatic difficulties that can impact quality of life for patients living with an injury. Impaired hippocampal function and synaptic alterations have been implicated in contributing to cognitive difficulties in experimental TBI models. In the synapse, neuronal communication is facilitated by the regulated release of neurotransmitters from docking presynaptic vesicles. The synaptic vesicle glycoprotein 2 (SV2) isoforms SV2A and SV2B play central roles in the maintenance of the readily releasable pool of vesicles and the coupling of calcium to the N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex responsible for vesicle docking. Recently, we reported the findings of TBI-induced reductions in presynaptic vesicle density and SNARE complex formation; however, the effect of TBI on SV2 is unknown. To investigate this, rats were subjected to controlled cortical impact (CCI) or sham control surgery. Abundance of SV2A and SV2B were assessed at 1, 3, 7 and 14 days post-injury by immunoblot. SV2A and SV2B were reduced in the cortex at several time points and in the hippocampus at every time point assessed. Immunohistochemical staining and quantitative intensity measurements completed at 14 days post-injury revealed reduced SV2A immunoreactivity in all hippocampal subregions and reduced SV2B immunoreactivity in the molecular layer after CCI. Reductions in SV2A abundance and immunoreactivity occurred concomitantly with motor dysfunction and spatial learning and memory impairments in the 2 weeks post-injury. These findings provide novel evidence for the effect of TBI on SV2 with implications for impaired neurotransmission neurobehavioral dysfunction after TBI.
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Affiliation(s)
- Katherine M Fronczak
- Neurological Surgery, University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
| | - Youming Li
- Neurological Surgery, University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
| | - Jeremy Henchir
- Neurological Surgery, University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
| | - C Edward Dixon
- Neurological Surgery, University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA.,VA Pittsburgh Healthcare System, Pittsburgh, PA, USA
| | - Shaun W Carlson
- Neurological Surgery, University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA.
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2
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Contreras-García IJ, Gómez-Lira G, Phillips-Farfán BV, Pichardo-Macías LA, García-Cruz ME, Chávez-Pacheco JL, Mendoza-Torreblanca JG. Synaptic Vesicle Protein 2A Expression in Glutamatergic Terminals Is Associated with the Response to Levetiracetam Treatment. Brain Sci 2021; 11:brainsci11050531. [PMID: 33922424 PMCID: PMC8145097 DOI: 10.3390/brainsci11050531] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/24/2021] [Accepted: 03/24/2021] [Indexed: 12/05/2022] Open
Abstract
Synaptic vesicle protein 2A (SV2A), the target of the antiepileptic drug levetiracetam (LEV), is expressed ubiquitously in all synaptic terminals. Its levels decrease in patients and animal models of epilepsy. Thus, changes in SV2A expression could be a critical factor in the response to LEV. Epilepsy is characterized by an imbalance between excitation and inhibition, hence SV2A levels in particular terminals could also influence the LEV response. SV2A expression was analyzed in the epileptic hippocampus of rats which responded or not to LEV, to clarify if changes in SV2A alone or together with glutamatergic or GABAergic markers may predict LEV resistance. Wistar rats were administered saline (control) or pilocarpine to induce epilepsy. These groups were subdivided into untreated or LEV-treated groups. All epileptic rats were video-monitored to assess their number of seizures. Epileptic rats with an important seizure reduction (>50%) were classified as responders. SV2A, vesicular γ-aminobutyric acid transporter and vesicular glutamate transporter (VGLUT) expression were assessed by immunostaining. SV2A expression was not modified during epilepsy. However, responders showed ≈55% SV2A-VGLUT co-expression in comparison with the non-responder group (≈40%). Thus, SV2A expression in glutamatergic terminals may be important for the response to LEV treatment.
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Affiliation(s)
- Itzel Jatziri Contreras-García
- Área de Neurociencias, Biología de la Reproducción, Unidad Iztapalapa, Universidad Autónoma Metropolitana, Ciudad de México 09340, Mexico;
| | - Gisela Gómez-Lira
- Departamento de Farmacobiología, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México 14330, Mexico;
| | - Bryan Víctor Phillips-Farfán
- Laboratorio de Nutrición Experimental, Subdirección de Medicina Experimental, Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico;
| | - Luz Adriana Pichardo-Macías
- Departamento de Fisiología, Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Ciudad de México 07738, Mexico;
| | - Mercedes Edna García-Cruz
- Laboratorio de Neurociencias, Subdirección de Medicina Experimental, Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico;
| | - Juan Luis Chávez-Pacheco
- Laboratorio de Farmacología, Subdirección de Medicina Experimental, Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico;
| | - Julieta G. Mendoza-Torreblanca
- Laboratorio de Neurociencias, Subdirección de Medicina Experimental, Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico;
- Correspondence: ; Tel.: +52-55-840900 (ext. 1425) or +52-55-21836345
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Butler CR, Boychuk JA, Pomerleau F, Alcala R, Huettl P, Ai Y, Jakobsson J, Whiteheart SW, Gerhardt GA, Smith BN, Slevin JT. Modulation of epileptogenesis: A paradigm for the integration of enzyme-based microelectrode arrays and optogenetics. Epilepsy Res 2019; 159:106244. [PMID: 31816591 DOI: 10.1016/j.eplepsyres.2019.106244] [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: 09/21/2019] [Revised: 10/22/2019] [Accepted: 11/22/2019] [Indexed: 02/03/2023]
Abstract
BACKGROUND Genesis of acquired epilepsy includes transformations spanning genetic-to- network-level modifications, disrupting the regional excitatory/inhibitory balance. Methodology concurrently tracking changes at multiple levels is lacking. Here, viral vectors are used to differentially express two opsin proteins in neuronal populations within dentate gyrus (DG) of hippocampus. When activated, these opsins induced excitatory or inhibitory neural output that differentially affected neural networks and epileptogenesis. In vivo measures included behavioral observation coupled to real-time measures of regional glutamate flux using ceramic-based amperometric microelectrode arrays (MEAs). RESULTS Using MEA technology, phasic increases of extracellular glutamate were recorded immediately upon application of blue light/488 nm to DG of rats previously transfected with an AAV 2/5 vector containing an (excitatory) channelrhodopsin-2 transcript. Rats receiving twice-daily 30-sec light stimulation to DG ipsilateral to viral transfection progressed through Racine seizure stages. AAV 2/5 (inhibitory) halorhodopsin-transfected rats receiving concomitant amygdalar kindling and DG light stimuli were kindled significantly more slowly than non-stimulated controls. In in vitro slice preparations, both excitatory and inhibitory responses were independently evoked in dentate granule cells during appropriate light stimulation. Latency to response and sensitivity of responses suggest a degree of neuron subtype-selective functional expression of the transcripts. CONCLUSIONS This study demonstrates the potential for coupling MEA technology and optogenetics for real-time neurotransmitter release measures and modification of seizure susceptibility in animal models of epileptogenesis. This microelectrode/optogenetic technology could prove useful for characterization of network and system level dysfunction in diseases involving imbalanced excitatory/inhibitory control of neuron populations and guide development of future treatment strategies.
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Affiliation(s)
- Corwin R Butler
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, 40536, United States
| | - Jeffery A Boychuk
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, 40536, United States; Epilepsy Center, University of Kentucky, Lexington, KY, 40536, United States
| | - Francois Pomerleau
- Department of Neuroscience, College of Medicine, University of Kentucky, Lexington, KY, 40536, United States; Brain Restoration Center, University of Kentucky, Lexington, KY, 40356, United States
| | - Ramona Alcala
- Department of Neurology, College of Medicine, University of Kentucky, Lexington, KY, 40536, United States
| | - Peter Huettl
- Department of Neuroscience, College of Medicine, University of Kentucky, Lexington, KY, 40536, United States; Brain Restoration Center, University of Kentucky, Lexington, KY, 40356, United States
| | - Yi Ai
- Department of Neuroscience, College of Medicine, University of Kentucky, Lexington, KY, 40536, United States
| | - Johan Jakobsson
- Wallenburg Neuroscience Center, Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Sidney W Whiteheart
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, 40536, United States; Veterans Affairs Medical Center, Lexington, KY, 40536, United States
| | - Greg A Gerhardt
- Epilepsy Center, University of Kentucky, Lexington, KY, 40536, United States; Spinal Cord and Brain Injury Research Center (SCoBIRC), University of Kentucky, Lexington, KY, 40536, United States; Department of Neuroscience, College of Medicine, University of Kentucky, Lexington, KY, 40536, United States; Department of Neurology, College of Medicine, University of Kentucky, Lexington, KY, 40536, United States; Brain Restoration Center, University of Kentucky, Lexington, KY, 40356, United States
| | - Bret N Smith
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, 40536, United States; Epilepsy Center, University of Kentucky, Lexington, KY, 40536, United States; Spinal Cord and Brain Injury Research Center (SCoBIRC), University of Kentucky, Lexington, KY, 40536, United States; Department of Neuroscience, College of Medicine, University of Kentucky, Lexington, KY, 40536, United States
| | - John T Slevin
- Epilepsy Center, University of Kentucky, Lexington, KY, 40536, United States; Department of Neurology, College of Medicine, University of Kentucky, Lexington, KY, 40536, United States; Veterans Affairs Medical Center, Lexington, KY, 40536, United States; Brain Restoration Center, University of Kentucky, Lexington, KY, 40356, United States.
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Ciruelas K, Marcotulli D, Bajjalieh SM. Synaptic vesicle protein 2: A multi-faceted regulator of secretion. Semin Cell Dev Biol 2019; 95:130-141. [PMID: 30826548 DOI: 10.1016/j.semcdb.2019.02.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 01/11/2019] [Accepted: 02/21/2019] [Indexed: 01/01/2023]
Abstract
Synaptic Vesicle Protein 2 (SV2) comprises a recently evolved family of proteins unique to secretory vesicles that undergo calcium-regulated exocytosis. In this review we consider SV2s' structural features, evolution, and function and discuss its therapeutic potential as the receptors for an expanding class of drugs used to treat epilepsy and cognitive decline.
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Affiliation(s)
- Kristine Ciruelas
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - Daniele Marcotulli
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - Sandra M Bajjalieh
- Department of Pharmacology, University of Washington, Seattle, WA, United States.
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5
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Differential expression of SV2A in hippocampal glutamatergic and GABAergic terminals during postnatal development. Brain Res 2019; 1715:73-83. [PMID: 30905653 DOI: 10.1016/j.brainres.2019.03.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 03/08/2019] [Accepted: 03/20/2019] [Indexed: 01/15/2023]
Abstract
The function of synaptic vesicle protein 2A (SV2A) has not been clearly identified, although it has an essential role in normal neurotransmission. Changes in SV2A expression have been linked to several diseases that could implicate an imbalance between excitation and inhibition, such as epilepsy. Although it is known that SV2A expression is necessary for survival, SV2A expression and its relationship with γ-aminobutyric acid (GABA) and glutamate neurotransmitter systems along development has not been addressed. This report follows SV2A expression levels in the rat hippocampus and their association with glutamatergic and GABAergic terminals along postnatal development. Total SV2A expression was assessed by real time PCR and western blot, while immunofluorescence was used to identify SV2A protein in the different hippocampal layers and its co-localization with GABA or glutamate vesicular transporters. SV2A was dynamically regulated along development and its association with GABA or glutamate transporters varied in the different hippocampal layers. In the principal cells layers (granular and pyramidal), SV2A protein was preferentially localized to GABAergic terminals, while in the hilus and stratum lucidum SV2A was associated mainly to glutamatergic terminals. Although SV2A was ubiquitously expressed in the entire hippocampus, it established a differential association with excitatory or inhibitory terminals, which could contribute to the maturation of excitatory/inhibitory balance.
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Tokudome K, Shimizu S, Serikawa T, Ohno Y. [Function of synaptic vesicle protein 2A (SV2A) as a novel therapeutic target for epilepsy]. Nihon Yakurigaku Zasshi 2018; 152:275-280. [PMID: 30531097 DOI: 10.1254/fpj.152.275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Epilepsy is a chronic neurologic disease characterized by recurrent seizures, affecting nearly 1% of the population. Synaptic vesicle protein 2A (SV2A) is a membrane protein specifically expressed in synaptic vesicles and is now implicated in the pathogenesis of epileptic disorders. This is because 1) Sv2a-knockout mice exhibit severe seizures, 2) SV2A serves as a specific binding site for certain antiepileptics (e.g., levetiracetam and its analogues) and 3) the SV2A expression changes under various epileptic conditions both in animals (e.g., kindling) and humans (e.g., intractable temporal lobe epilepsy and focal cortical dysplasia). Furthermore, it has been shown that a missense mutation in the SV2A gene caused intractable epilepsy, involuntary movements and developmental retardation, indicating a causative role of SV2A dysfunction in epilepsy. In order to explore the mechanism of SV2A in modulating development of epileptogenesis, we recently developed a novel rat model (Sv2aL174Q rat) carrying a missense mutation (Leu174Gln) in the Sv2a gene. These rats were highly susceptible to the kindling development associated with repeated pentylenetetrazole treatments or electrical stimulations of the amygdala. In addition, the Sv2aL174Q mutation specifically impaired depolarization-induced GABA, but not glutamate, release in the hippocampus and amygdala. All this evidence indicates that the SV2A-GABAergic system plays a crucial role in modulating epileptogenesis and encourages discovery research into the novel antiepileptic agents which enhance the function of the SV2A-GABA system.
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Affiliation(s)
- Kentaro Tokudome
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences
| | - Saki Shimizu
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences
| | - Tadao Serikawa
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences
| | - Yukihiro Ohno
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences
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7
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Klein P, Diaz A, Gasalla T, Whitesides J. A review of the pharmacology and clinical efficacy of brivaracetam. Clin Pharmacol 2018; 10:1-22. [PMID: 29403319 PMCID: PMC5783144 DOI: 10.2147/cpaa.s114072] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Brivaracetam (BRV; Briviact) is a new antiepileptic drug (AED) approved for adjunctive treatment of focal (partial-onset) seizures in adults. BRV is a selective, high-affinity ligand for synaptic vesicle 2A (SV2A) with 15- to 30-fold higher affinity than levetiracetam, the first AED acting on SV2A. It has high lipid solubility and rapid brain penetration, with engagement of the target molecule, SV2A, within minutes of administration. BRV has potent broad-spectrum antiepileptic activity in animal models. Phase I studies indicated BRV was well tolerated and showed a favorable pharmacokinetic profile over a wide dose range following single (10–1,000 mg) and multiple (200–800 mg/day) oral dosing. Three pivotal Phase III studies have demonstrated promising efficacy and a good safety and tolerability profile across doses of 50–200 mg/day in the adjunctive treatment of refractory focal seizures. Long-term data indicate that the response to BRV is sustained, with good tolerability and retention rate. BRV is highly effective in patients experiencing secondarily generalized tonic–clonic seizures. Safety data to date suggest a favorable psychiatric adverse effect profile in controlled studies, although limited postmarketing data are available. BRV is easy to use, with no titration and little drug–drug interaction. It can be initiated at target dose with no titration. Efficacy is seen on day 1 of oral use in a significant percentage of patients. Intravenous administration in a 2-minute bolus and 15-minute infusion is well tolerated. Here, we review the pharmacology, pharmacokinetics, and clinical data of BRV.
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Affiliation(s)
- Pavel Klein
- Mid-Atlantic Epilepsy and Sleep Center, Bethesda, MD, USA
| | - Anyzeila Diaz
- Neurology Patient Value Unit, UCB Pharma, Smyrna, GA, USA
| | - Teresa Gasalla
- Neurology Patient Value Unit, UCB Pharma, Monheim am Rhein, Germany
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Batten SR, Matveeva EA, Whiteheart SW, Vanaman TC, Gerhardt GA, Slevin JT. Linking kindling to increased glutamate release in the dentate gyrus of the hippocampus through the STXBP5/tomosyn-1 gene. Brain Behav 2017; 7:e00795. [PMID: 28948088 PMCID: PMC5607557 DOI: 10.1002/brb3.795] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 06/29/2017] [Accepted: 07/02/2017] [Indexed: 12/19/2022] Open
Abstract
INTRODUCTION In kindling, repeated electrical stimulation of certain brain areas causes progressive and permanent intensification of epileptiform activity resulting in generalized seizures. We focused on the role(s) of glutamate and a negative regulator of glutamate release, STXBP5/tomosyn-1, in kindling. METHODS Stimulating electrodes were implanted in the amygdala and progression to two successive Racine stage 5 seizures was measured in wild-type and STXBP5/tomosyn-1-/- (Tom-/-) animals. Glutamate release measurements were performed in distinct brain regions using a glutamate-selective microelectrode array (MEA). RESULTS Naïve Tom-/- mice had significant increases in KCl-evoked glutamate release compared to naïve wild type as measured by MEA of presynaptic release in the hippocampal dentate gyrus (DG). Kindling progression was considerably accelerated in Tom-/- mice, requiring fewer stimuli to reach a fully kindled state. Following full kindling, MEA measurements of both kindled Tom+/+ and Tom-/- mice showed significant increases in KCl-evoked and spontaneous glutamate release in the DG, indicating a correlation with the fully kindled state independent of genotype. Resting glutamate levels in all hippocampal subregions were significantly lower in the kindled Tom-/- mice, suggesting possible changes in basal control of glutamate circuitry in the kindled Tom-/- mice. CONCLUSIONS Our studies demonstrate that increased glutamate release in the hippocampal DG correlates with acceleration of the kindling process. Although STXBP5/tomosyn-1 loss increased evoked glutamate release in naïve animals contributing to their prokindling phenotype, the kindling process can override any attenuating effect of STXBP5/tomosyn-1. Loss of this "braking" effect of STXBP5/tomosyn-1 on kindling progression may set in motion an alternative but ultimately equally ineffective compensatory response, detected here as reduced basal glutamate release.
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Affiliation(s)
- Seth R. Batten
- Department of PsychologyUniversity of KentuckyCollege of Arts and SciencesLexingtonKYUSA
| | - Elena A. Matveeva
- Department of Molecular & Cellular BiochemistryUniversity of Kentucky Medical CenterLexingtonKYUSA
| | - Sidney W. Whiteheart
- Department of Molecular & Cellular BiochemistryUniversity of Kentucky Medical CenterLexingtonKYUSA
| | - Thomas C. Vanaman
- Department of Molecular & Cellular BiochemistryUniversity of Kentucky Medical CenterLexingtonKYUSA
| | - Greg A. Gerhardt
- Department of NeuroscienceUniversity of Kentucky Medical CenterLexingtonKYUSA
- Department of NeurologyUniversity of Kentucky Medical CenterLexingtonKYUSA
| | - John T. Slevin
- Neurology ServiceVeterans Affairs Medical CenterLexingtonKYUSA
- Department of NeurologyUniversity of Kentucky Medical CenterLexingtonKYUSA
- Department of Pharmacology and Nutritional SciencesUniversity of Kentucky Medical CenterLexingtonKYUSA
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Bartholome O, Van den Ackerveken P, Sánchez Gil J, de la Brassinne Bonardeaux O, Leprince P, Franzen R, Rogister B. Puzzling Out Synaptic Vesicle 2 Family Members Functions. Front Mol Neurosci 2017; 10:148. [PMID: 28588450 PMCID: PMC5438990 DOI: 10.3389/fnmol.2017.00148] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 05/02/2017] [Indexed: 01/18/2023] Open
Abstract
Synaptic vesicle proteins 2 (SV2) were discovered in the early 80s, but the clear demonstration that SV2A is the target of efficacious anti-epileptic drugs from the racetam family stimulated efforts to improve understanding of its role in the brain. Many functions have been suggested for SV2 proteins including ions or neurotransmitters transport or priming of SVs. Moreover, several recent studies highlighted the link between SV2 and different neuronal disorders such as epilepsy, Schizophrenia (SCZ), Alzheimer's or Parkinson's disease. In this review article, we will summarize our present knowledge on SV2A function(s) and its potential role(s) in the pathophysiology of various brain disorders.
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Affiliation(s)
- Odile Bartholome
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences, University of LiègeLiège, Belgium
| | | | - Judit Sánchez Gil
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences, University of LiègeLiège, Belgium
| | | | - Pierre Leprince
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences, University of LiègeLiège, Belgium
| | - Rachelle Franzen
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences, University of LiègeLiège, Belgium
| | - Bernard Rogister
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences, University of LiègeLiège, Belgium.,Department of Neurology, Centre Hospitalier Universitaire de Liège (CHU), University of LiègeLiège, Belgium
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Löscher W, Gillard M, Sands ZA, Kaminski RM, Klitgaard H. Synaptic Vesicle Glycoprotein 2A Ligands in the Treatment of Epilepsy and Beyond. CNS Drugs 2016; 30:1055-1077. [PMID: 27752944 PMCID: PMC5078162 DOI: 10.1007/s40263-016-0384-x] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The synaptic vesicle glycoprotein SV2A belongs to the major facilitator superfamily (MFS) of transporters and is an integral constituent of synaptic vesicle membranes. SV2A has been demonstrated to be involved in vesicle trafficking and exocytosis, processes crucial for neurotransmission. The anti-seizure drug levetiracetam was the first ligand to target SV2A and displays a broad spectrum of anti-seizure activity in various preclinical models. Several lines of preclinical and clinical evidence, including genetics and protein expression changes, support an important role of SV2A in epilepsy pathophysiology. While the functional consequences of SV2A ligand binding are not fully elucidated, studies suggest that subsequent SV2A conformational changes may contribute to seizure protection. Conversely, the recently discovered negative SV2A modulators, such as UCB0255, counteract the anti-seizure effect of levetiracetam and display procognitive properties in preclinical models. More broadly, dysfunction of SV2A may also be involved in Alzheimer's disease and other types of cognitive impairment, suggesting potential novel therapies for levetiracetam and its congeners. Furthermore, emerging data indicate that there may be important roles for two other SV2 isoforms (SV2B and SV2C) in the pathogenesis of epilepsy, as well as other neurodegenerative diseases. Utilization of recently developed SV2A positron emission tomography ligands will strengthen and reinforce the pharmacological evidence that SV2A is a druggable target, and will provide a better understanding of its role in epilepsy and other neurological diseases, aiding in further defining the full therapeutic potential of SV2A modulation.
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Affiliation(s)
- Wolfgang Löscher
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hannover, Germany.
- Center for Systems Neuroscience, Hannover, Germany.
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Tokudome K, Okumura T, Terada R, Shimizu S, Kunisawa N, Mashimo T, Serikawa T, Sasa M, Ohno Y. A Missense Mutation of the Gene Encoding Synaptic Vesicle Glycoprotein 2A (SV2A) Confers Seizure Susceptibility by Disrupting Amygdalar Synaptic GABA Release. Front Pharmacol 2016; 7:210. [PMID: 27471467 PMCID: PMC4943941 DOI: 10.3389/fphar.2016.00210] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Accepted: 06/30/2016] [Indexed: 12/14/2022] Open
Abstract
Synaptic vesicle glycoprotein 2A (SV2A) is specifically expressed in the membranes of synaptic vesicles and modulates action potential-dependent neurotransmitter release. To explore the role of SV2A in the pathogenesis of epileptic disorders, we recently generated a novel rat model (Sv2aL174Q rat) carrying a missense mutation of the Sv2a gene and showed that the Sv2aL174Q rats were hypersensitive to kindling development (Tokudome et al., 2016). Here, we further conducted behavioral and neurochemical studies to clarify the pathophysiological mechanisms underlying the seizure vulnerability in Sv2aL174Q rats. Sv2aL174Q rats were highly susceptible to pentylenetetrazole (PTZ)-induced seizures, yielding a significantly higher seizure scores and seizure incidence than the control animals. Brain mapping analysis of Fos expression, a biological marker of neural excitation, revealed that the seizure threshold level of PTZ region-specifically elevated Fos expression in the amygdala in Sv2aL174Q rats. In vivo microdialysis study showed that the Sv2aL174Q mutation preferentially reduced high K+ (depolarization)-evoked GABA release, but not glutamate release, in the amygdala. In addition, specific control of GABA release by SV2A was supported by its predominant expression in GABAergic neurons, which were co-stained with antibodies against SV2A and glutamate decarboxylase 1. The present results suggest that dysfunction of SV2A by the missense mutation elevates seizure susceptibility in rats by preferentially disrupting synaptic GABA release in the amygdala, illustrating the crucial role of amygdalar SV2A-GABAergic system in epileptogenesis.
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Affiliation(s)
- Kentaro Tokudome
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Takahiro Okumura
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Ryo Terada
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Saki Shimizu
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Naofumi Kunisawa
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Tomoji Mashimo
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto UniversityKyoto, Japan; Institute of Experimental Animal Sciences, Graduate School of Medicine, Osaka UniversityOsaka, Japan
| | - Tadao Serikawa
- Laboratory of Pharmacology, Osaka University of Pharmaceutical SciencesOsaka, Japan; Institute of Laboratory Animals, Graduate School of Medicine, Kyoto UniversityKyoto, Japan
| | | | - Yukihiro Ohno
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
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12
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Synaptic vesicle glycoprotein 2A (SV2A) regulates kindling epileptogenesis via GABAergic neurotransmission. Sci Rep 2016; 6:27420. [PMID: 27265781 PMCID: PMC4893657 DOI: 10.1038/srep27420] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 05/18/2016] [Indexed: 02/08/2023] Open
Abstract
Synaptic vesicle glycoprotein 2A (SV2A) is a prototype synaptic vesicle protein regulating action potential-dependent neurotransmitters release. SV2A also serves as a specific binding site for certain antiepileptics and is implicated in the treatment of epilepsy. Here, to elucidate the role of SV2A in modulating epileptogenesis, we generated a novel rat model (Sv2aL174Q rat) carrying a Sv2a-targeted missense mutation (L174Q) and analyzed its susceptibilities to kindling development. Although animals homozygous for the Sv2aL174Q mutation exhibited normal appearance and development, they are susceptible to pentylenetetrazole (PTZ) seizures. In addition, development of kindling associated with repeated PTZ treatments or focal stimulation of the amygdala was markedly facilitated by the Sv2aL174Q mutation. Neurochemical studies revealed that the Sv2aL174Q mutation specifically reduced depolarization-induced GABA, but not glutamate, release in the hippocampus without affecting basal release or the SV2A expression level in GABAergic neurons. In addition, the Sv2aL174Q mutation selectively reduced the synaptotagmin1 (Syt1) level among the exocytosis-related proteins examined. The present results demonstrate that dysfunction of SV2A due to the Sv2aL174Q mutation impairs the synaptic GABA release by reducing the Syt1 level and facilitates the kindling development, illustrating the crucial role of SV2A-GABA system in modulating kindling epileptogenesis.
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Xi Z, Deng W, Wang L, Xiao F, Li J, Wang Z, Wang X, Mi X, Wang N, Wang X. Association of Alpha-Soluble NSF Attachment Protein with Epileptic Seizure. J Mol Neurosci 2015; 57:417-25. [DOI: 10.1007/s12031-015-0596-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 06/02/2015] [Indexed: 01/02/2023]
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Lee J, Daniels V, Sands ZA, Lebon F, Shi J, Biggin PC. Exploring the interaction of SV2A with racetams using homology modelling, molecular dynamics and site-directed mutagenesis. PLoS One 2015; 10:e0116589. [PMID: 25692762 PMCID: PMC4333566 DOI: 10.1371/journal.pone.0116589] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 12/11/2014] [Indexed: 11/18/2022] Open
Abstract
The putative Major Facilitator Superfamily (MFS) transporter, SV2A, is the target for levetiracetam (LEV), which is a successful anti-epileptic drug. Furthermore, SV2A knock out mice display a severe seizure phenotype and die after a few weeks. Despite this, the mode of action of LEV is not known at the molecular level. It would be extremely desirable to understand this more fully in order to aid the design of improved anti-epileptic compounds. Since there is no structure for SV2A, homology modelling can provide insight into the ligand-binding site. However, it is not a trivial process to build such models, since SV2A has low sequence identity to those MFS transporters whose structures are known. A further level of complexity is added by the fact that it is not known which conformational state of the receptor LEV binds to, as multiple conformational states have been inferred by tomography and ligand binding assays or indeed, if binding is exclusive to a single state. Here, we explore models of both the inward and outward facing conformational states of SV2A (according to the alternating access mechanism for MFS transporters). We use a sequence conservation analysis to help guide the homology modelling process and generate the models, which we assess further with Molecular Dynamics (MD). By comparing the MD results in conjunction with docking and simulation of a LEV-analogue used in radioligand binding assays, we were able to suggest further residues that line the binding pocket. These were confirmed experimentally. In particular, mutation of D670 leads to a complete loss of binding. The results shed light on the way LEV analogues may interact with SV2A and may help with the on-going design of improved anti-epileptic compounds.
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Affiliation(s)
- Joanna Lee
- Structural Bioinformatics and Computational Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom
| | | | - Zara A. Sands
- UCB Pharma S.A., Chemin du Foriest, B-1420 Braine-l’Alleud, Belgium
| | - Florence Lebon
- UCB Pharma S.A., Chemin du Foriest, B-1420 Braine-l’Alleud, Belgium
| | - Jiye Shi
- UCB Pharma S.A., Chemin du Foriest, B-1420 Braine-l’Alleud, Belgium
| | - Philip C. Biggin
- Structural Bioinformatics and Computational Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom
- * E-mail:
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Iwata K, Matsuzaki H, Tachibana T, Ohno K, Yoshimura S, Takamura H, Yamada K, Matsuzaki S, Nakamura K, Tsuchiya KJ, Matsumoto K, Tsujii M, Sugiyama T, Katayama T, Mori N. N-ethylmaleimide-sensitive factor interacts with the serotonin transporter and modulates its trafficking: implications for pathophysiology in autism. Mol Autism 2014; 5:33. [PMID: 24834316 PMCID: PMC4022412 DOI: 10.1186/2040-2392-5-33] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 04/24/2014] [Indexed: 01/23/2023] Open
Abstract
Background Changes in serotonin transporter (SERT) function have been implicated in autism. SERT function is influenced by the number of transporter molecules present at the cell surface, which is regulated by various cellular mechanisms including interactions with other proteins. Thus, we searched for novel SERT-binding proteins and investigated whether the expression of one such protein was affected in subjects with autism. Methods Novel SERT-binding proteins were examined by a pull-down system. Alterations of SERT function and membrane expression upon knockdown of the novel SERT-binding protein were studied in HEK293-hSERT cells. Endogenous interaction of SERT with the protein was evaluated in mouse brains. Alterations in the mRNA expression of SERT (SLC6A4) and the SERT-binding protein in the post-mortem brains and the lymphocytes of autism patients were compared to nonclinical controls. Results N-ethylmaleimide-sensitive factor (NSF) was identified as a novel SERT-binding protein. NSF was co-localized with SERT at the plasma membrane, and NSF knockdown resulted in decreased SERT expression at the cell membranes and decreased SERT uptake function. NSF was endogenously co-localized with SERT and interacted with SERT. While SLC6A4 expression was not significantly changed, NSF expression tended to be reduced in post-mortem brains, and was significantly reduced in lymphocytes of autistic subjects, which correlated with the severity of the clinical symptoms. Conclusions These data clearly show that NSF interacts with SERT under physiological conditions and is required for SERT membrane trafficking and uptake function. A possible role for NSF in the pathophysiology of autism through modulation of SERT trafficking, is suggested.
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Affiliation(s)
- Keiko Iwata
- Research Center for Child Mental Development, University of Fukui, Fukui, Japan ; Department of Development of Functional Brain Activities, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Fukui, Japan
| | - Hideo Matsuzaki
- Research Center for Child Mental Development, University of Fukui, Fukui, Japan ; Department of Development of Functional Brain Activities, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Fukui, Japan ; Research Center for Child Mental Development, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Taro Tachibana
- Department of Bioengineering, Graduate School of Engineering, Osaka City University, Osaka, Japan
| | - Koji Ohno
- Department of Anatomy, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Saori Yoshimura
- Department of Bioengineering, Graduate School of Engineering, Osaka City University, Osaka, Japan
| | - Hironori Takamura
- Department of Molecular Brain Science, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Suita, Osaka, Japan ; Molecular Research Center for Children's Mental Development, United Graduate School of Child Development, Osaka University, Suita, Osaka, Japan
| | - Kohei Yamada
- Department of Molecular Brain Science, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Suita, Osaka, Japan ; Molecular Research Center for Children's Mental Development, United Graduate School of Child Development, Osaka University, Suita, Osaka, Japan
| | - Shinsuke Matsuzaki
- Department of Molecular Brain Science, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Suita, Osaka, Japan
| | - Kazuhiko Nakamura
- Department of Psychiatry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Kenji J Tsuchiya
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Kaori Matsumoto
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Masatsugu Tsujii
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, Hamamatsu, Japan ; Faculty of Contemporary Sociology, Chukyo University, Toyota, Japan
| | - Toshirou Sugiyama
- Department of Child and Adolescent Psychiatry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Taiichi Katayama
- Department of Molecular Brain Science, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Suita, Osaka, Japan
| | - Norio Mori
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, Hamamatsu, Japan ; Department of Psychiatry, Hamamatsu University School of Medicine, Hamamatsu, Japan
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Mendoza-Torreblanca JG, Vanoye-Carlo A, Phillips-Farfán BV, Carmona-Aparicio L, Gómez-Lira G. Synaptic vesicle protein 2A: basic facts and role in synaptic function. Eur J Neurosci 2013; 38:3529-39. [DOI: 10.1111/ejn.12360] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 08/09/2013] [Accepted: 08/17/2013] [Indexed: 10/26/2022]
Affiliation(s)
| | | | | | | | - Gisela Gómez-Lira
- Department of Pharmacobiology; Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional; Calzada de los Tenorios 235 Col. Granjas Coapa C.P. 14330 D. F., Mexico
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Transcriptomic profiling of human peritumoral neocortex tissues revealed genes possibly involved in tumor-induced epilepsy. PLoS One 2013; 8:e56077. [PMID: 23418513 PMCID: PMC3572021 DOI: 10.1371/journal.pone.0056077] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 01/09/2013] [Indexed: 12/11/2022] Open
Abstract
The molecular mechanism underlying tumor-induced epileptogenesis is poorly understood. Alterations in the peritumoral microenvironment are believed to play a significant role in inducing epileptogenesis. We hypothesize that the change of gene expression in brain peritumoral tissues may contribute to the increased neuronal excitability and epileptogenesis. To identify the genes possibly involved in tumor-induced epilepsy, a genome-wide gene expression profiling was conducted using Affymetrix HG U133 plus 2.0 arrays and RNAs derived from formalin-fixed paraffin embedded (FFPE) peritumoral cortex tissue slides from 5-seizure vs. 5-non-seizure low grade brain tumor patients. We identified many differentially expressed genes (DEGs). Seven dysregulated genes (i.e., C1QB, CALCRL, CCR1, KAL1, SLC1A2, SSTR1 and TYRO3) were validated by qRT-PCR, which showed a high concordance. Principal Component Analysis (PCA) showed that epilepsy subjects were clustered together tightly (except one sample) and were clearly separated from the non-epilepsy subjects. Molecular functional categorization showed that significant portions of the DEGs functioned as receptor activity, molecular binding including enzyme binding and transcription factor binding. Pathway analysis showed these DEGs were mainly enriched in focal adhesion, ECM-receptor interaction, and cell adhesion molecules pathways. In conclusion, our study showed that dysregulation of gene expression in the peritumoral tissues may be one of the major mechanisms of brain tumor induced-epilepsy. However, due to the small sample size of the present study, further validation study is needed. A deeper characterization on the dysregulated genes involved in brain tumor-induced epilepsy may shed some light on the management of epilepsy due to brain tumors.
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Hanaya R, Hosoyama H, Sugata S, Tokudome M, Hirano H, Tokimura H, Kurisu K, Serikawa T, Sasa M, Arita K. Low distribution of synaptic vesicle protein 2A and synaptotagimin-1 in the cerebral cortex and hippocampus of spontaneously epileptic rats exhibiting both tonic convulsion and absence seizure. Neuroscience 2012; 221:12-20. [DOI: 10.1016/j.neuroscience.2012.06.058] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 06/25/2012] [Accepted: 06/25/2012] [Indexed: 10/28/2022]
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19
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Venkatesan K, Alix P, Marquet A, Doupagne M, Niespodziany I, Rogister B, Seutin V. Altered balance between excitatory and inhibitory inputs onto CA1 pyramidal neurons from SV2A-deficient but not SV2B-deficient mice. J Neurosci Res 2012; 90:2317-27. [DOI: 10.1002/jnr.23111] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 06/20/2012] [Accepted: 06/21/2012] [Indexed: 11/07/2022]
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20
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Ohno Y, Okumura T, Terada R, Ishihara S, Serikawa T, Sasa M. Kindling-associated SV2A expression in hilar GABAergic interneurons of the mouse dentate gyrus. Neurosci Lett 2012; 510:93-8. [DOI: 10.1016/j.neulet.2012.01.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 12/25/2011] [Accepted: 01/04/2012] [Indexed: 01/14/2023]
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Nowack A, Malarkey EB, Yao J, Bleckert A, Hill J, Bajjalieh SM. Levetiracetam reverses synaptic deficits produced by overexpression of SV2A. PLoS One 2011; 6:e29560. [PMID: 22220214 PMCID: PMC3248421 DOI: 10.1371/journal.pone.0029560] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 11/30/2011] [Indexed: 11/18/2022] Open
Abstract
Levetiracetam is an FDA-approved drug used to treat epilepsy and other disorders of the nervous system. Although it is known that levetiracetam binds the synaptic vesicle protein SV2A, how drug binding affects synaptic functioning remains unknown. Here we report that levetiracetam reverses the effects of excess SV2A in autaptic hippocampal neurons. Expression of an SV2A-EGFP fusion protein produced a ∼1.5-fold increase in synaptic levels of SV2, and resulted in reduced synaptic release probability. The overexpression phenotype parallels that seen in neurons from SV2 knockout mice, which experience severe seizures. Overexpression of SV2A also increased synaptic levels of the calcium-sensor protein synaptotagmin, an SV2-binding protein whose stability and trafficking are regulated by SV2. Treatment with levetiracetam rescued normal neurotransmission and restored normal levels of SV2 and synaptotagmin at the synapse. These results indicate that changes in SV2 expression in either direction impact neurotransmission, and suggest that levetiracetam may modulate SV2 protein interactions.
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Affiliation(s)
- Amy Nowack
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
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Matveeva EA, Price DA, Whiteheart SW, Vanaman TC, Gerhardt GA, Slevin JT. Reduction of vesicle-associated membrane protein 2 expression leads to a kindling-resistant phenotype in a murine model of epilepsy. Neuroscience 2011; 202:77-86. [PMID: 22183055 DOI: 10.1016/j.neuroscience.2011.11.055] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 11/23/2011] [Accepted: 11/24/2011] [Indexed: 11/13/2022]
Abstract
Our previous work has correlated permanent alterations in the rat neurosecretory machinery with epileptogenesis. Such findings highlighted the need for a greater understanding of the molecular mechanisms underlying epilepsy so that novel therapeutic regimens can be designed. To this end, we examined kindling in transgenic mice with a defined reduction of a key element of the neurosecretory machinery: the v-SNARE (vesicle-bound SNAP [soluble NSF attachment protein] receptor), synaptobrevin/vesicle-associated membrane protein 2 (VAMP2). Initial analysis of biochemical markers, which previously displayed kindling-dependent alterations in rat hippocampal synaptosomes, showed similar trends in both wild-type and VAMP2(+/-) mice, demonstrating that kindled rat and mouse models are comparable. This report focuses on the effects that a ~50% reduction of synaptosomal VAMP2 has on the progression of electrical kindling and on glutamate release in hippocampal subregions. Our studies show that epileptogenesis is dramatically attenuated in VAMP2(+/-) mice, requiring both higher current and more stimulations to reach a fully kindled state (two successive Racine stage 5 seizures). Progression through the five identifiable Racine stages was slower and more variable in the VAMP2(+/-) animals compared with the almost linear progression seen in wild-type littermates. Consistent with the expected effects of reducing a major neuronal v-SNARE, glutamate-selective, microelectrode array (MEA) measurements in specific hippocampal subregions of VAMP2(+/-) mice showed significant reductions in potassium-evoked glutamate release. Taken together these studies demonstrate that manipulating the levels of the neurosecretory machinery not only affects neurotransmitter release but also mitigates kindling-induced epileptogenesis.
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Affiliation(s)
- E A Matveeva
- Department of Molecular and Cellular Biochemistry, University of Kentucky Medical Center, Lexington, KY, USA
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Matveeva EA, Davis VA, Whiteheart SW, Vanaman TC, Gerhardt GA, Slevin JT. Kindling-induced asymmetric accumulation of hippocampal 7S SNARE complexes correlates with enhanced glutamate release. Epilepsia 2011; 53:157-67. [PMID: 22150629 DOI: 10.1111/j.1528-1167.2011.03345.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
PURPOSE To correlate kindling-associated alterations of the neurotransmitter secretory machinery, glutamate release in the trisynaptic hippocampal excitatory pathway, and the behavioral evolution of kindling-induced epileptogenesis. METHOD Neurotransmitter release requires the fusion of vesicle and plasma membranes; it is initiated by formation of a stable, ternary complex (7SC) of SNARE [soluble N-ethylmaleimide sensitive factor (NSF) attachment protein receptor] proteins. Quantitative Western blotting was used to monitor levels of 7SC and SNARE regulators [NSF, SV2 (synaptic vesicle protein 2)] in hippocampal synaptosomes from amygdala-kindled animals. Hippocampal synaptic glutamate release was measured in vivo with a unique microelectrode array (MEA) that uses glutamate oxidase to catalyze the breakdown of glutamate into a reporter molecule. KEY FINDINGS Ipsilateral hippocampal accumulation of 7SC developed with onset of amygdalar kindling, but became permanent only in animals stimulated to at least Racine stage 3; the ratio peaked and did not increase with more than two consecutive stage 5 seizures. Chronic 7SC asymmetry was seen in entorhinal cortex and the hippocampal formation, particularly in dentate gyrus (DG) and CA1, but not in the other brain areas examined. There was a strong correlation between asymmetric 7SC accumulation and increased total hippocampal SV2. Following a 30-day latent period, amplitudes of spontaneous synaptic glutamate release were enhanced in ipsilateral DG and reduced in ipsilateral CA3 of kindled animals; increased volleys of synaptic glutamate activity were seen in ipsilateral CA1. SIGNIFICANCE Amygdalar kindling is associated with chronic changes in the flow of glutamate signaling in the excitatory trisynaptic pathway and with early but permanent changes in the mechanics of vesicular release in ipsilateral hippocampal formation.
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Affiliation(s)
- Elena A Matveeva
- Departments of Molecular & Cellular Biochemistry, University of Kentucky Medical Center, Lexington, Kentucky, USA
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Requirements for the catalytic cycle of the N-ethylmaleimide-Sensitive Factor (NSF). BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1823:159-71. [PMID: 21689688 DOI: 10.1016/j.bbamcr.2011.06.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/23/2011] [Accepted: 06/06/2011] [Indexed: 12/23/2022]
Abstract
The N-ethylmaleimide-Sensitive Factor (NSF) was one of the initial members of the ATPases Associated with various cellular Activities Plus (AAA(+)) family. In this review, we discuss what is known about the mechanism of NSF action and how that relates to the mechanisms of other AAA(+) proteins. Like other family members, NSF binds to a protein complex (i.e., SNAP-SNARE complex) and utilizes ATP hydrolysis to affect the conformations of that complex. SNAP-SNARE complex disassembly is essential for SNARE recycling and sustained membrane trafficking. NSF is a homo-hexamer; each protomer is composed of an N-terminal domain, NSF-N, and two adjacent AAA-domains, NSF-D1 and NSF-D2. Mutagenesis analysis has established specific roles for many of the structural elements of NSF-D1, the catalytic ATPase domain, and NSF-N, the SNAP-SNARE binding domain. Hydrodynamic analysis of NSF, labeled with (Ni(2+)-NTA)(2)-Cy3, detected conformational differences in NSF, in which the ATP-bound conformation appears more compact than the ADP-bound form. This indicates that NSF undergoes significant conformational changes as it progresses through its ATP-hydrolysis cycle. Incorporating these data, we propose a sequential mechanism by which NSF uses NSF-N and NSF-D1 to disassemble SNAP-SNARE complexes. We also illustrate how analytical centrifugation might be used to study other AAA(+) proteins.
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Protein quantification at the single vesicle level reveals that a subset of synaptic vesicle proteins are trafficked with high precision. J Neurosci 2011; 31:1461-70. [PMID: 21273430 DOI: 10.1523/jneurosci.3805-10.2011] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Protein sorting represents a potential point of regulation in neurotransmission because it dictates the protein composition of synaptic vesicles, the organelle that mediates transmitter release. Although the average number of most vesicle proteins has been estimated using bulk biochemical approaches (Takamori et al., 2006), no information exists on the intervesicle variability of protein number, and thus on the precision with which proteins are sorted to vesicles. To address this, we adapted a single molecule quantification approach (Mutch et al., 2007) and used it to quantify both the average number and variance of seven integral membrane proteins in brain synaptic vesicles. We report that four vesicle proteins, SV2, the proton ATPase, Vglut1, and synaptotagmin 1, showed little intervesicle variation in number, indicating they are sorted to vesicles with high precision. In contrast, the apparent number of VAMP2/synaptobrevin 2, synaptophysin, and synaptogyrin demonstrated significant intervesicle variability. These findings place constraints on models of protein function at the synapse and raise the possibility that changes in vesicle protein expression affect vesicle composition and functioning.
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Barakauskas VE, Beasley CL, Barr AM, Ypsilanti AR, Li HY, Thornton AE, Wong H, Rosokilja G, Mann JJ, Mancevski B, Jakovski Z, Davceva N, Ilievski B, Dwork AJ, Falkai P, Honer WG. A novel mechanism and treatment target for presynaptic abnormalities in specific striatal regions in schizophrenia. Neuropsychopharmacology 2010; 35:1226-38. [PMID: 20072114 PMCID: PMC3055413 DOI: 10.1038/npp.2009.228] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 11/06/2009] [Accepted: 11/20/2009] [Indexed: 02/01/2023]
Abstract
Abnormalities of amount and function of presynaptic terminals may have an important role in the mechanism of illness in schizophrenia. The SNARE proteins (SNAP-25, syntaxin, and VAMP) are enriched in presynaptic terminals, where they interact to form a functional complex to facilitate vesicle fusion. SNARE protein amounts are altered in the cortical regions in schizophrenia, but studies of protein-protein interactions are limited. We extended these investigations to the striatal regions (such as the nucleus accumbens, ventromedial caudate (VMC), and dorsal caudate) relevant to disease symptoms. In addition to measuring SNARE protein levels, we studied SNARE protein-protein interactions using a novel ELISA method. The possible effect of antipsychotic treatment was investigated in parallel in the striatum of rodents that were administered haloperidol and clozapine. In schizophrenia samples, compared with controls, SNAP-25 was 32% lower (P=0.015) and syntaxin was 26% lower (P=0.006) in the VMC. In contrast, in the same region, SNARE protein-protein interactions were higher in schizophrenia (P=0.008). Confocal microscopy of schizophrenia and control VMC showed qualitatively similar SNARE protein immunostaining. Haloperidol treatment of rats increased levels of SNAP-25 (mean 24%, P=0.003), syntaxin (mean 18%, P=0.010), and VAMP (mean 16%, P=0.001), whereas clozapine increased only the VAMP level (mean 13%, P=0.004). Neither drug altered SNARE protein-protein interactions. These results indicate abnormalities of amount and interactions of proteins directly related to presynaptic function in the VMC in schizophrenia. SNARE proteins and their interactions may be a novel target for the development of therapeutics.
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Affiliation(s)
- Vilte E Barakauskas
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Clare L Beasley
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Alasdair M Barr
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Athena R Ypsilanti
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Hong-Ying Li
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Allen E Thornton
- Department of Psychology, Simon Fraser University, Burnaby, BC, Canada
| | - Hubert Wong
- Department of Health Care and Epidemiology, University of British Columbia, Vancouver, BC, Canada
| | - Gorazd Rosokilja
- Department of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, New York, NY, USA
- Department of Psychiatry, Surgeons of Columbia University, New York, NY, USA
- Macedonian Academy of Sciences and Arts, University ‘SS. Cyril and Methodius' Skopje, Macedonia
| | - J John Mann
- Department of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, New York, NY, USA
- Department of Psychiatry, Surgeons of Columbia University, New York, NY, USA
| | - Branislav Mancevski
- Department of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, New York, NY, USA
- Department of Psychiatry, Surgeons of Columbia University, New York, NY, USA
| | - Zlatko Jakovski
- Institute for Forensic Medicine, University ‘SS. Cyril and Methodius,' Skopje, Macedonia
| | - Natasha Davceva
- Institute for Forensic Medicine, University ‘SS. Cyril and Methodius,' Skopje, Macedonia
| | - Boro Ilievski
- Department of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, New York, NY, USA
- Institute for Pathology, University ‘SS. Cyril and Methodius,', Skopje, Macedonia
| | - Andrew J Dwork
- Department of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, New York, NY, USA
- Department of Psychiatry, Surgeons of Columbia University, New York, NY, USA
- Department of Pathology and Cell Biology, College of Physicians, Surgeons of Columbia University, New York, NY, USA
| | - Peter Falkai
- Department of Psychiatry, Göttingen University, Göttingen, Germany
| | - William G Honer
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
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Ohno Y, Ishihara S, Terada R, Kikuta M, Sofue N, Kawai Y, Serikawa T, Sasa M. Preferential increase in the hippocampal synaptic vesicle protein 2A (SV2A) by pentylenetetrazole kindling. Biochem Biophys Res Commun 2009; 390:415-20. [DOI: 10.1016/j.bbrc.2009.09.035] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2009] [Accepted: 09/05/2009] [Indexed: 10/20/2022]
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Matveeva EA, Vanaman TC, Whiteheart SW, Slevin JT. Levetiracetam prevents kindling-induced asymmetric accumulation of hippocampal 7S SNARE complexes. Epilepsia 2008; 49:1749-58. [PMID: 18513349 DOI: 10.1111/j.1528-1167.2008.01687.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE Understanding the molecular mechanisms underlying epilepsy is crucial to designing novel therapeutic regimens. This report focuses on alterations in the secretory machinery responsible for neurotransmitter (NT) release. Soluble N-ethylmaleimide sensitive factor (NSF) attachment protein receptor (SNARE) complexes mediate the fusion of synaptic vesicle and active zone membranes, thus mediating NT secretion. SNARE regulators control where and when SNARE complexes are formed. Previous studies showed an asymmetric accumulation of 7S SNARE complexes (7SC) in the ipsilateral hippocampus of kindled animals. The present studies probe the persistence of 7SC accumulation and the effect of the anticonvulsant, levetiracetam (LEV), on 7SC and SNARE regulators. METHOD Quantitative Western blotting was used to monitor levels of 7SC and SNARE regulators in hippocampal synaptosomes from kindled animals both before and after LEV treatment. RESULTS The asymmetric accumulation of 7SC is present 1-year postamygdalar kindling. The synaptic vesicle protein, synaptic vesicle protein 2 (SV2), a primary LEV-binding protein, and the SNARE regulator Tomosyn increase, whereas NSF decreases in association with this accumulation. Treatment with LEV prevented kindling-induced accumulation of SV2, but did not affect the transient increase of Tomosyn or the long-term decrease NSF. LEV treatment retarded the electrical and behavioral concomitants of amygdalar kindling coincident with a decrease in accumulation of 7SC. CONCLUSIONS The ipsilateral hippocampal accumulation of SNARE complexes is an altered molecular process associated with kindling that appears permanent. Kindling epileptogenesis alters synaptosomal levels of the SNARE regulators: NSF, SV2, and Tomosyn. Concomitant treatment with LEV reverses the kindling-induced 7SC accumulation and increase of SV2.
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Affiliation(s)
- Elena A Matveeva
- Department of Molecular & Cellular Biochemistry, University of Kentucky, Medical Center, Lexington, Kentucky, USA
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Zhao C, Slevin JT, Whiteheart SW. Cellular functions of NSF: not just SNAPs and SNAREs. FEBS Lett 2007; 581:2140-9. [PMID: 17397838 PMCID: PMC1948069 DOI: 10.1016/j.febslet.2007.03.032] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 03/07/2007] [Indexed: 12/26/2022]
Abstract
N-ethylmaleimide sensitive factor (NSF) is an ATPases associated with various cellular activities protein (AAA), broadly required for intracellular membrane fusion. NSF functions as a SNAP receptor (SNARE) chaperone which binds, through soluble NSF attachment proteins (SNAPs), to SNARE complexes and utilizes the energy of ATP hydrolysis to disassemble them thus facilitating SNARE recycling. While this is a major function of NSF, it does seem to interact with other proteins, such as the AMPA receptor subunit, GluR2, and beta2-AR and is thought to affect their trafficking patterns. New data suggest that NSF may be regulated by transient post-translational modifications such as phosphorylation and nitrosylation. These new aspects of NSF function as well as its role in SNARE complex dynamics will be discussed.
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Affiliation(s)
- Chunxia Zhao
- Departmental of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, USA
| | - John T. Slevin
- Neurology Service, Department of Veterans Affairs Medical Center, Departments of Neurology and Molecular and Biomedical Pharmacology, University of Kentucky Medical Center, Lexington, KY, USA
| | - Sidney W. Whiteheart
- Departmental of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, USA
- *Corresponding author. 741 South Limestone, BBSRB B261, Lexington, KY 40536, USA. Phone: 1-859-257-4882. Fax: 1-859-257-2283. E-mail address:
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Sutula TP, Dudek FE. Unmasking recurrent excitation generated by mossy fiber sprouting in the epileptic dentate gyrus: an emergent property of a complex system. PROGRESS IN BRAIN RESEARCH 2007; 163:541-63. [PMID: 17765737 DOI: 10.1016/s0079-6123(07)63029-5] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Seizure-induced sprouting of the mossy fiber pathway in the dentate gyrus has been observed nearly universally in experimental models of limbic epilepsy and in the epileptic human hippocampus. The observation of progressive mossy fiber sprouting induced by kindling demonstrated that even a few repeated seizures are sufficient to alter synaptic connectivity and circuit organization. As it is now recognized that seizures induce synaptic reorganization in hippocampal and cortical pathways, the implications of seizure-induced synaptic reorganization for circuit properties and function have been subjects of intense interest. Detailed anatomical characterization of the sprouted mossy fiber pathway has revealed that the overwhelming majority of sprouted synapses in the inner molecular layer of the dentate gyrus form recurrent excitatory connections, and are thus likely to contribute to recurrent excitation and potentially to enhanced susceptibility to seizures. Nevertheless, difficulties in detecting functional abnormalities in circuits reorganized by mossy fiber sprouting and the fact that some sprouted axons appear to form synapses with inhibitory interneurons have been cited as evidence that sprouting may not contribute to seizure susceptibility, but could form recurrent inhibitory circuits and be a compensatory response to prevent seizures. Quantitative analysis of the synaptic connections of the sprouted mossy fiber pathway, assessment of the functional features of sprouted circuitry using reliable physiological measures, and the perspective of complex systems analysis of neural circuits strongly support the view that the functional effects of the recurrent excitatory circuits formed by mossy fiber sprouting after seizures or injury emerge only conditionally and intermittently, as observed with spontaneous seizures in human epilepsy. The recognition that mossy fiber sprouting is induced after hippocampal injury and seizures and contributes conditionally to emergence of recurrent excitation has provided a conceptual framework for understanding how injury and seizure-induced circuit reorganization may contribute to paroxysmal network synchronization, epileptogenesis, and the consequences of repeated seizures, and thus has had a major influence on understanding of fundamental aspects of the epilepsies.
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Affiliation(s)
- Thomas P Sutula
- Department of Neurology H6/570 CSC, University of Wisconsin, 600 Highland Avenue, Madison, WI 53792, USA.
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