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Cassiano C, Eletto D, Tosco A, Riccio R, Monti MC, Casapullo A. Determining the Effect of Pterostilbene on Insulin Secretion Using Chemoproteomics. Molecules 2020; 25:E2885. [PMID: 32585851 PMCID: PMC7356329 DOI: 10.3390/molecules25122885] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 06/18/2020] [Accepted: 06/22/2020] [Indexed: 12/13/2022] Open
Abstract
Pterostilbene, the 3,5-dimethoxy derivative of resveratrol, is a well-known polyphenolic compound, mainly found in blueberries, grapevines, and Pterocarpus marsupium heartwood, which has recently attracted a great deal of attention due to its wide bio-pharmacological profile. Moreover, pterostilbene is more lipophilic than resveratrol, with a consequently better bioavailability and a more interesting therapeutic potential. In this work, a chemoproteomic approach, based on affinity chromatography, was applied on pterostilbene in the attempt to identify the biological targets responsible for its bioactivity. On this basis, syntaxins, a group of proteins involved in the formation of SNARE complexes mediating vesicles exocytosis, were selected among the most interesting pterostilbene interactors. In vitro and in cell assays gave evidence of the pterostilbene ability to reduce insulin secretion on glucose-stimulated pancreatic beta cells, opening the way to potential applications of pterostilbene as a supplement in the care of insulin-dependent metabolic disorders.
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Affiliation(s)
- Chiara Cassiano
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, Italy; (C.C.); (D.E.); (A.T.); (R.R.)
- Department of Pharmacy, University of Naples “Federico II”, Via D., Montesano 49, 80131 Naples, Italy
| | - Daniela Eletto
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, Italy; (C.C.); (D.E.); (A.T.); (R.R.)
| | - Alessandra Tosco
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, Italy; (C.C.); (D.E.); (A.T.); (R.R.)
| | - Raffaele Riccio
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, Italy; (C.C.); (D.E.); (A.T.); (R.R.)
| | - Maria Chiara Monti
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, Italy; (C.C.); (D.E.); (A.T.); (R.R.)
| | - Agostino Casapullo
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, Italy; (C.C.); (D.E.); (A.T.); (R.R.)
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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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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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Schiro PG, Gadd JC, Yen GS, Chiu DT. High-throughput fluorescence-activated nanoscale subcellular sorter with single-molecule sensitivity. J Phys Chem B 2012; 116:10490-5. [PMID: 22574902 DOI: 10.1021/jp3019233] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent single-cell and single-molecule studies have shown that a variety of subpopulations exist within biological systems, such as synaptic vesicles, that have previously been overlooked in common bulk studies. By isolating and enriching these various subpopulations, detailed analysis with a variety of analytical techniques can be done to further understand the role that various subpopulations play in cellular dynamics and how alterations to these subpopulations affect the overall function of the biological system. Previous sorters lack the sensitivity, sorting speed, and efficiency to isolate synaptic vesicles and other nanoscale systems. This paper describes the development of a fluorescence-activated nanoscale subcellular sorter that can sort nearly 10 million objects per hour with single-molecule sensitivity. Utilizing a near-nanoscale channel system, we were able to achieve upward of 91% recovery of desired objects with a 99.7% purity.
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Affiliation(s)
- Perry G Schiro
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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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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Abnormalities in α/β-CaMKII and related mechanisms suggest synaptic dysfunction in hippocampus of LPA1 receptor knockout mice. Int J Neuropsychopharmacol 2011; 14:941-53. [PMID: 20942999 DOI: 10.1017/s1461145710001240] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Lysophosphatidic acid (LPA) is a natural lysophospholipid that regulates neuronal maturation. In mice, the deletion of the LPA1 receptor causes some phenotypic defects partly overlapping with those found in schizophrenia. In this study, we identified molecular abnormalities in hippocampal synaptic mechanisms involved in glutamatergic neurotransmission, which allow further characterization of synaptic aberrations in LPA1 knockout (KO) mice. At the synaptic level, we found dysregulation of Ca2+/calmodulin (CaM)-dependent kinase II (CaMKII) activity and phosphorylation, with markedly higher Ca2+-dependent kinase activity, probably related to increased expression levels of the β isoform of CaMKII. Conversely, although the synaptic Ca2+-independent activity of the enzyme was unchanged, autophosphorylation levels of both α and β isoforms were significantly increased in LPA1 KO mice. Moreover, in LPA1 KO mice the α/β isoform ratio of CaMKII, which plays a key role in neuronal maturation during development, was markedly decreased, as found previously in schizophrenia patients. At post-synaptic level, LPA1 KO mice showed changes in expression, phosphorylation and interactions of NMDA and AMPA receptor subunits that are consistent with basal strengthening of glutamatergic synapses. However, we measured a reduction of nuclear cAMP responsive element-binding protein phosphorylation, suggesting that activation of the NMDA receptor does not occur at the intracellular signalling level. At the presynaptic level, in line with previous evidence from schizophrenia patients and animal models of pathology, LPA1 KO mice showed accumulation of SNARE protein complexes. This study shows that CaMKII and related synaptic mechanisms at glutamatergic synapses are strongly dysregulated in LPA1 KO mice.
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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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Musazzi L, Milanese M, Farisello P, Zappettini S, Tardito D, Barbiero VS, Bonifacino T, Mallei A, Baldelli P, Racagni G, Raiteri M, Benfenati F, Bonanno G, Popoli M. Acute stress increases depolarization-evoked glutamate release in the rat prefrontal/frontal cortex: the dampening action of antidepressants. PLoS One 2010; 5:e8566. [PMID: 20052403 PMCID: PMC2797327 DOI: 10.1371/journal.pone.0008566] [Citation(s) in RCA: 190] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Accepted: 12/06/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Behavioral stress is recognized as a main risk factor for neuropsychiatric diseases. Converging evidence suggested that acute stress is associated with increase of excitatory transmission in certain forebrain areas. Aim of this work was to investigate the mechanism whereby acute stress increases glutamate release, and if therapeutic drugs prevent the effect of stress on glutamate release. METHODOLOGY/FINDINGS Rats were chronically treated with vehicle or drugs employed for therapy of mood/anxiety disorders (fluoxetine, desipramine, venlafaxine, agomelatine) and then subjected to unpredictable footshock stress. Acute stress induced marked increase in depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex in superfusion, and the chronic drug treatments prevented the increase of glutamate release. Stress induced rapid increase in the circulating levels of corticosterone in all rats (both vehicle- and drug-treated), and glutamate release increase was blocked by previous administration of selective antagonist of glucocorticoid receptor (RU 486). On the molecular level, stress induced accumulation of presynaptic SNARE complexes in synaptic membranes (both in vehicle- and drug-treated rats). Patch-clamp recordings of pyramidal neurons in the prefrontal cortex revealed that stress increased glutamatergic transmission through both pre- and postsynaptic mechanisms, and that antidepressants may normalize it by reducing release probability. CONCLUSIONS/SIGNIFICANCE Acute footshock stress up-regulated depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex. Stress-induced increase of glutamate release was dependent on stimulation of glucocorticoid receptor by corticosterone. Because all drugs employed did not block either elevation of corticosterone or accumulation of SNARE complexes, the dampening action of the drugs on glutamate release must be downstream of these processes. This novel effect of antidepressants on the response to stress, shown here for the first time, could be related to the therapeutic action of these drugs.
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Affiliation(s)
- Laura Musazzi
- Department of Pharmacological Sciences, Center of Neuropharmacology and Center of Excellence on Neurodegenerative Diseases, University of Milano, Milano, Italy
| | - Marco Milanese
- Department of Experimental Medicine, Section of Pharmacology and Toxicology, University of Genova, Genova, Italy
- Center of Excellence for Biomedical Research and National Institute of Neuroscience, Genova, Italy
| | - Pasqualina Farisello
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, Genova, Italy
- Department of Experimental Medicine, Section of Physiology, University of Genova and National Institute of Neuroscience, Genova, Italy
| | - Simona Zappettini
- Department of Experimental Medicine, Section of Pharmacology and Toxicology, University of Genova, Genova, Italy
- Center of Excellence for Biomedical Research and National Institute of Neuroscience, Genova, Italy
| | - Daniela Tardito
- Department of Pharmacological Sciences, Center of Neuropharmacology and Center of Excellence on Neurodegenerative Diseases, University of Milano, Milano, Italy
| | - Valentina S. Barbiero
- Department of Pharmacological Sciences, Center of Neuropharmacology and Center of Excellence on Neurodegenerative Diseases, University of Milano, Milano, Italy
| | - Tiziana Bonifacino
- Department of Experimental Medicine, Section of Pharmacology and Toxicology, University of Genova, Genova, Italy
- Center of Excellence for Biomedical Research and National Institute of Neuroscience, Genova, Italy
| | - Alessandra Mallei
- Department of Pharmacological Sciences, Center of Neuropharmacology and Center of Excellence on Neurodegenerative Diseases, University of Milano, Milano, Italy
| | - Pietro Baldelli
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, Genova, Italy
- Department of Experimental Medicine, Section of Physiology, University of Genova and National Institute of Neuroscience, Genova, Italy
| | - Giorgio Racagni
- Department of Pharmacological Sciences, Center of Neuropharmacology and Center of Excellence on Neurodegenerative Diseases, University of Milano, Milano, Italy
- Department of Experimental Medicine, Section of Pharmacology and Toxicology, University of Genova, Genova, Italy
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, Genova, Italy
- Istituto di Ricovero e Cura a Carattere Scientifico San Giovanni di Dio - Fatebenefratelli, Brescia, Italy
- Center of Excellence for Biomedical Research and National Institute of Neuroscience, Genova, Italy
- Department of Experimental Medicine, Section of Physiology, University of Genova and National Institute of Neuroscience, Genova, Italy
| | - Maurizio Raiteri
- Department of Experimental Medicine, Section of Pharmacology and Toxicology, University of Genova, Genova, Italy
- Center of Excellence for Biomedical Research and National Institute of Neuroscience, Genova, Italy
| | - Fabio Benfenati
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, Genova, Italy
- Department of Experimental Medicine, Section of Physiology, University of Genova and National Institute of Neuroscience, Genova, Italy
| | - Giambattista Bonanno
- Department of Experimental Medicine, Section of Pharmacology and Toxicology, University of Genova, Genova, Italy
- Center of Excellence for Biomedical Research and National Institute of Neuroscience, Genova, Italy
| | - Maurizio Popoli
- Department of Pharmacological Sciences, Center of Neuropharmacology and Center of Excellence on Neurodegenerative Diseases, University of Milano, Milano, Italy
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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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Matveeva EA, Vanaman TC, Whiteheart SW, Slevin JT. Asymmetric accumulation of hippocampal 7S SNARE complexes occurs regardless of kindling paradigm. Epilepsy Res 2007; 73:266-74. [PMID: 17174072 PMCID: PMC1868484 DOI: 10.1016/j.eplepsyres.2006.11.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2006] [Revised: 10/24/2006] [Accepted: 11/10/2006] [Indexed: 01/25/2023]
Abstract
Modifications of neurotransmission may contribute to the synchronization of neuronal networks that are a hallmark of epileptic seizures. In this study we examine the synaptosomal proteins involved in neurotransmitter release to determine if alterations in their interactions correlate with the chronic epileptic state. Using quantitative western blotting, we measured the levels of 7S SNARE complexes and SNARE effectors in the effected hippocampi from animals that were electrically kindled through stimulation from one of three different foci. All three kindling paradigms, amygdalar, entorhinal, and septal, were associated with an accumulation of 7S SNARE complexes in the ipsilateral hippocampus, measured 1 month after completion of kindling. Of the eight SNARE effectors examined (alpha-SNAP, NSF, SV2A/B, Munc18a/nSec1, Munc13-1, Complexins 1 and 2, and synaptotagmin I), there was a statistically significant bihemispheric increase of hippocampal SV2 and decrease of NSF upon kindling; neither by itself would be expected to account for the asymmetry of SNARE complex distribution. These data suggest that an ipsilateral hippocampal accumulation of SNARE complexes is a permanent alteration of kindling-induced epilepsy, regardless of stimulation pathway. The significance of these findings toward a molecular understanding of epilepsy will be discussed.
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Affiliation(s)
- Elena A. Matveeva
- Elena A. Matveeva, Ph. D., Dept. Molecular & Cellular Biochemistry, University of Kentucky Medical Center, Lexington, Kentucky 40536-0509, Tel: 859 323-6702 Ext 245, FAX: 859 257-2283,
| | - Thomas C. Vanaman
- Thomas C. Vanaman, Ph.D., Dept. Molecular & Cellular Biochemistry, University of Kentucky Medical Center, Lexington, Kentucky 40536-0509, Tel: 859 257-1347, FAX: 859 257-9670,
| | - Sidney W. Whiteheart
- Sidney W. Whiteheart, Ph.D., Dept. Molecular & Cellular Biochemistry, University of Kentucky Medical Center, Lexington, Kentucky 40536, Tel: 859 323-6702, Ext 245 FAX: 859 257-2283,
| | - John T. Slevin
- John T. Slevin, MD, Neurology Service Veterans Affairs Medical Center, Lexington, KY 40511 and Departments of Neurology and Molecular & Biomedical Pharmacology, University of Kentucky Medical Center, Tel: 859 323-6702 Ext 245, FAX: 859 281-4817,
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Ozbas-Gerçeker F, Redeker S, Boer K, Ozgüç M, Saygi S, Dalkara T, Soylemezoglu F, Akalan N, Baayen JC, Gorter JA, Aronica E. Serial analysis of gene expression in the hippocampus of patients with mesial temporal lobe epilepsy. Neuroscience 2006; 138:457-74. [PMID: 16413123 DOI: 10.1016/j.neuroscience.2005.11.043] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Revised: 11/04/2005] [Accepted: 11/20/2005] [Indexed: 10/25/2022]
Abstract
Hippocampal sclerosis constitutes the most frequent neuropathological finding in patients with medically intractable mesial temporal lobe epilepsy. Serial analysis of gene expression was used to get a global view of the gene profile in human hippocampus in control condition and in epileptic condition associated with hippocampal sclerosis. Libraries were generated from control hippocampus, obtained by rapid autopsy, and from hippocampal surgical specimens of patients with mesial temporal lobe epilepsy and the classical pattern of hippocampal sclerosis. More than 50,000 tags were analyzed (28,282, control hippocampus; 25,953, hippocampal sclerosis) resulting in 9206 (control hippocampus) and 9599 (hippocampal sclerosis) unique tags (genes), each representing a specific mRNA transcript. Comparison of the two libraries resulted in the identification of 143 transcripts that were differentially expressed. These genes belong to a variety of functional classes, including basic metabolism, transcription regulation, protein synthesis and degradation, signal transduction, structural proteins, regeneration and synaptic plasticity and genes of unknown identity of function. The database generated by this study provides an extensive inventory of genes expressed in human control hippocampus, identifies new high-abundant genes associated with altered hippocampal morphology in patients with mesial temporal lobe epilepsy and serves as a reference for future studies aimed at detecting hippocampal transcriptional responses under various pathological conditions.
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Affiliation(s)
- F Ozbas-Gerçeker
- Department of Medical Biology, Hacettepe University, Faculty of Medicine, 06100 Sihhiye, Ankara, Turkey
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Rüder C, Reimer T, Delgado-Martinez I, Hermosilla R, Engelsberg A, Nehring R, Dörken B, Rehm A. EBAG9 adds a new layer of control on large dense-core vesicle exocytosis via interaction with Snapin. Mol Biol Cell 2005; 16:1245-57. [PMID: 15635093 PMCID: PMC551489 DOI: 10.1091/mbc.e04-09-0817] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Regulated exocytosis is subject to several modulatory steps that include phosphorylation events and transient protein-protein interactions. The estrogen receptor-binding fragment-associated gene9 (EBAG9) gene product was recently identified as a modulator of tumor-associated O-linked glycan expression in nonneuronal cells; however, this molecule is expressed physiologically in essentially all mammalian tissues. Particular interest has developed toward this molecule because in some human tumor entities high expression levels correlated with clinical prognosis. To gain insight into the cellular function of EBAG9, we scored for interaction partners by using the yeast two-hybrid system. Here, we demonstrate that EBAG9 interacts with Snapin, which is likely to be a modulator of Synaptotagmin-associated regulated exocytosis. Strengthening of this interaction inhibited regulated secretion of neuropeptide Y from PC12 cells, whereas evoked neurotransmitter release from hippocampal neurons remained unaltered. Mechanistically, EBAG9 decreased phosphorylation of Snapin; subsequently, association of Snapin with synaptosome-associated protein of 25 kDa (SNAP25) and SNAP23 was diminished. We suggest that the occurrence of SNAP23, Snapin, and EBAG9 also in nonneuronal cells might extend the modulatory role of EBAG9 to a broad range of secretory cells. The conjunction between EBAG9 and Snapin adds an additional layer of control on exocytosis processes; in addition, mechanistic evidence is provided that inhibition of phosphorylation has a regulatory function in exocytosis.
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Affiliation(s)
- Constantin Rüder
- Department of Hematology, Oncology, and Tumor Immunology, Max-Delbrück-Center for Molecular Medicine, 13125 Berlin, Germany
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Kubista H, Edelbauer H, Boehm S. Evidence for structural and functional diversity among SDS-resistant SNARE complexes in neuroendocrine cells. J Cell Sci 2004; 117:955-66. [PMID: 14762114 DOI: 10.1242/jcs.00941] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The core complex, formed by the SNARE proteins synaptobrevin 2, syntaxin 1 and SNAP-25, is an important component of the synaptic fusion machinery and shows remarkable in vitro stability, as exemplified by its SDS-resistance. In western blots, antibodies against one of these SNARE proteins reveal the existence of not only an SDS-resistant ternary complex but also as many as five bands between 60 and >200 kDa. Structural conformation as well as possible functions of these various complexes remained elusive. In western blots of protein extracts from PC12 cell membranes, an antibody against SNAP-25 detected two heat-sensitive SDS-resistant bands with apparent molecular weights of 100 and 230 kDa. A syntaxin antibody recognized only the 230 kDa band and required heat-treatment of the blotting membrane to detect the 100 kDa band. Various antibodies against synaptobrevin failed to detect SNARE complexes in conventional western blots and detected either the 100 kDa band or the 230 kDa band on heat-treated blotting membranes. When PC12 cells were exposed to various extracellular K(+)-concentrations (to evoke depolarization-induced Ca(2+) influx) or permeabilized in the presence of basal or elevated free Ca(2+), levels of these SNARE complexes were altered differentially: moderate Ca(2+) rises (</=1 microM) caused an increase, whereas Ca(2+) elevations of more than 1 microM led to a decrease in the 230 kDa band. Under both conditions the 100 kDa band was either increased or remained unchanged. Our data show that various SDS-resistant complexes occur in living cells and indicate that they represent SNARE complexes with different structures and diverging functions. The distinct behavior of these complexes under release-promoting conditions indicates that these SNARE structures have different roles in exocytosis.
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Affiliation(s)
- Helmut Kubista
- Department of Pharmacology, University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
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