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Ogunmowo TH, Jing H, Raychaudhuri S, Kusick GF, Imoto Y, Li S, Itoh K, Ma Y, Jafri H, Dalva MB, Chapman ER, Ha T, Watanabe S, Liu J. Membrane compression by synaptic vesicle exocytosis triggers ultrafast endocytosis. Nat Commun 2023; 14:2888. [PMID: 37210439 PMCID: PMC10199930 DOI: 10.1038/s41467-023-38595-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Accepted: 05/09/2023] [Indexed: 05/22/2023] Open
Abstract
Compensatory endocytosis keeps the membrane surface area of secretory cells constant following exocytosis. At chemical synapses, clathrin-independent ultrafast endocytosis maintains such homeostasis. This endocytic pathway is temporally and spatially coupled to exocytosis; it initiates within 50 ms at the region immediately next to the active zone where vesicles fuse. However, the coupling mechanism is unknown. Here, we demonstrate that filamentous actin is organized as a ring, surrounding the active zone at mouse hippocampal synapses. Assuming the membrane area conservation is due to this actin ring, our theoretical model suggests that flattening of fused vesicles exerts lateral compression in the plasma membrane, resulting in rapid formation of endocytic pits at the border between the active zone and the surrounding actin-enriched region. Consistent with model predictions, our data show that ultrafast endocytosis requires sufficient compression by exocytosis of multiple vesicles and does not initiate when actin organization is disrupted, either pharmacologically or by ablation of the actin-binding protein Epsin1. Our work suggests that membrane mechanics underlie the rapid coupling of exocytosis to endocytosis at synapses.
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Affiliation(s)
- Tyler H Ogunmowo
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Biochemistry, Cellular and Molecular Biology graduate program, Johns Hopkins University, Baltimore, MD, US
| | - Haoyuan Jing
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, US
| | - Sumana Raychaudhuri
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, US
| | - Grant F Kusick
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Biochemistry, Cellular and Molecular Biology graduate program, Johns Hopkins University, Baltimore, MD, US
| | - Yuuta Imoto
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, US
| | - Shuo Li
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Department of Ophthalmology, School of Medicine, Stanford University, Palo Alto, CA, US
| | - Kie Itoh
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, US
| | - Ye Ma
- Department of Biomedical Engineering, School of Medicine, Johns Hopkins University, Baltimore, MD, US
| | - Haani Jafri
- Department of Neuroscience and Jefferson Synaptic Biology Center, Thomas Jefferson University, Philadelphia, PA, US
| | - Matthew B Dalva
- Department of Neuroscience and Jefferson Synaptic Biology Center, Thomas Jefferson University, Philadelphia, PA, US
- Department of Cell and Molecular Biology and the Tulane Brain Institute, Tulane University, New Orleans, LA, US
| | - Edwin R Chapman
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, US
- Howard Hughes Medical Institute, Madison, WI, US
| | - Taekjip Ha
- Department of Biomedical Engineering, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Department of Biophysics and Biophysical Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD, US
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, US
- Howard Hughes Medical Institute, Baltimore, MD, US
| | - Shigeki Watanabe
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, US.
- Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, US.
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD, US.
| | - Jian Liu
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD, US.
- Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, US.
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Giving names to the actors of synaptic transmission: The long journey from synaptic vesicles to neural plasticity. ADVANCES IN PHARMACOLOGY 2021; 90:19-37. [PMID: 33706933 DOI: 10.1016/bs.apha.2020.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
More than a scientific paper or a review article, this is a remembrance of a unique time of science and life that the authors spent in Paul Greengard's laboratory at the Rockefeller University in New York in the 1980s and 1990s, forming the so-called synaptic vesicle group. It was a time in which the molecular mechanisms of synaptic transmission and the nature of the organelles in charge of storing and releasing neurotransmitter were just beginning to be understood. It was an exciting time in which the protein composition of synaptic vesicles started to be identified. It turned out that the interactions of synaptic vesicle proteins with the cytoskeleton and the presynaptic membrane and their modulation by protein phosphorylation represented an essential network regulating the efficiency of neurotransmitter release and thereby synaptic strength and plasticity. This is also a description of the distinct scientific journeys that the three authors took on going back to Europe and how they were strongly influenced by the generous and outstanding mentorship of Paul Greengard, his genuine interest in their lives and careers and the life-long friendship with him.
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Kim JH, Lee CH, Kim HG, Kim HR. Decreased dopamine in striatum and difficult locomotor recovery from MPTP insult after exposure to radiofrequency electromagnetic fields. Sci Rep 2019; 9:1201. [PMID: 30718744 PMCID: PMC6362053 DOI: 10.1038/s41598-018-37874-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 12/12/2018] [Indexed: 12/23/2022] Open
Abstract
Concern is growing about possible neuronal effects of human exposure to radiofrequency electromagnetic fields because of the increasing usage of cell phones and the close proximity of these devices to the brain when in use. We found that exposure to a radiofrequency electromagnetic field (RF-EMF) of 835 MHz (4.0 W/kg specific absorption rate [SAR] for 5 h/day for 12 weeks) affects striatal neurons in C57BL/6 mice. The number of synaptic vesicles (SVs) in striatal presynaptic boutons was significantly decreased after RF-EMF exposure. The expression levels of synapsin I and II were also significantly decreased in the striatum of the RF-EMF-exposed group. RF-EMF exposure led to a reduction in dopamine concentration in the striatum and also to a decrease in the expression of tyrosine hydroxylase in striatal neurons. Furthermore, in behavioral tests, exposure to RF-EMF impeded the recovery of locomotor activities after repeated treatments with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). These results suggest that the observed decrease in dopamine concentration in the striatum was caused by both a reduction in the number of dopaminergic neurons and a decline in the number of SVs. The decreased dopamine neuron numbers and concentration seen after RF-EMF exposure would have caused the difficult recovery after MPTP treatment. In summary, our results strongly suggest that exposing the brain to RF-EMF can decrease the number of SVs and dopaminergic neurons in the striatum. These primary changes impair the recovery of locomotor activities following MPTP damage to the striatum.
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Affiliation(s)
- Ju Hwan Kim
- Department of Pharmacology, College of Medicine, Dankook University, Cheonan, Chungnam, Republic of Korea
| | - Choong-Hyun Lee
- Department of Pharmacy, College of Pharmacy, Dankook University, Cheonan, Chungnam, Republic of Korea
| | - Hyung-Gun Kim
- Department of Pharmacology, College of Medicine, Dankook University, Cheonan, Chungnam, Republic of Korea
| | - Hak Rim Kim
- Department of Pharmacology, College of Medicine, Dankook University, Cheonan, Chungnam, Republic of Korea.
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Kim JH, Kim HJ, Yu DH, Kweon HS, Huh YH, Kim HR. Changes in numbers and size of synaptic vesicles of cortical neurons induced by exposure to 835 MHz radiofrequency-electromagnetic field. PLoS One 2017; 12:e0186416. [PMID: 29045446 PMCID: PMC5646811 DOI: 10.1371/journal.pone.0186416] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 09/29/2017] [Indexed: 12/17/2022] Open
Abstract
We studied the effects of radiofrequency electromagnetic fields (RF-EMFs) exposure on neuronal functions of mice. Particularly, we focused on RF-EMF effects on synaptic vesicles (SVs), which store neurotransmitters at axon terminals or synaptic boutons. C57 BL/6 mice were exposed to 835 MHz RF-EMF (4.0 W/kg SAR, for 5 h daily) and alterations in SVs at presynaptic terminals in the cerebral cortex were determined. Ultrastructure of randomly selected cortical neurons was observed using typical electron microscopy and bio-high voltage electron microscopy (Bio-HVEM) methods, which enable the estimation of the numbers and size of SVs. The density of the SVs (number /10 μm2 or 40 μm3) was significantly decreased in the presynaptic boutons of cortical neurons after RF-EMF exposure. Furthermore, qPCR and immunoblotting analyses revealed that the expression of synapsins I/II (Syns I/II) genes and proteins were significantly decreased in the cortical neurons of RF-EMF exposed mice. The present study suggested that alteration of SVs and Syn levels may result in alterations of neurotransmitters in the cerebral cortex following RF-EMF exposure.
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Affiliation(s)
- Ju Hwan Kim
- Department of Pharmacology, College of Medicine, Dankook University, Cheonan, Chungnam, South Korea
| | - Hyo-Jeong Kim
- Department of Pharmacology, College of Medicine, Dankook University, Cheonan, Chungnam, South Korea
- Center for Electron Microscopy Research, Korea Basic Science Institute, Ochang, Chungbuk, South Korea
| | - Da-Hyeon Yu
- Department of Pharmacology, College of Medicine, Dankook University, Cheonan, Chungnam, South Korea
| | - Hee-Seok Kweon
- Center for Electron Microscopy Research, Korea Basic Science Institute, Ochang, Chungbuk, South Korea
| | - Yang Hoon Huh
- Center for Electron Microscopy Research, Korea Basic Science Institute, Ochang, Chungbuk, South Korea
- * E-mail: (HRK); (YHH)
| | - Hak Rim Kim
- Department of Pharmacology, College of Medicine, Dankook University, Cheonan, Chungnam, South Korea
- * E-mail: (HRK); (YHH)
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Mechanical properties of silicone methacrylate microparticles determined by AFM Colloidal Probe Technique. POLYMER 2014. [DOI: 10.1016/j.polymer.2014.01.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Satori CP, Henderson MM, Krautkramer EA, Kostal V, Distefano MM, Arriaga EA. Bioanalysis of eukaryotic organelles. Chem Rev 2013; 113:2733-811. [PMID: 23570618 PMCID: PMC3676536 DOI: 10.1021/cr300354g] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Chad P. Satori
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, USA, 55455
| | - Michelle M. Henderson
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, USA, 55455
| | - Elyse A. Krautkramer
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, USA, 55455
| | - Vratislav Kostal
- Tescan, Libusina trida 21, Brno, 623 00, Czech Republic
- Institute of Analytical Chemistry ASCR, Veveri 97, Brno, 602 00, Czech Republic
| | - Mark M. Distefano
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, USA, 55455
| | - Edgar A. Arriaga
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, USA, 55455
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Satori CP, Kostal V, Arriaga EA. Review on recent advances in the analysis of isolated organelles. Anal Chim Acta 2012; 753:8-18. [PMID: 23107131 PMCID: PMC3484375 DOI: 10.1016/j.aca.2012.09.041] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 09/22/2012] [Accepted: 09/24/2012] [Indexed: 10/27/2022]
Abstract
The analysis of isolated organelles is one of the pillars of modern bioanalytical chemistry. This review describes recent developments on the isolation and characterization of isolated organelles both from living organisms and cell cultures. Salient reports on methods to release organelles focused on reproducibility and yield, membrane isolation, and integrated devices for organelle release. New developments on organelle fractionation after their isolation were on the topics of centrifugation, immunocapture, free flow electrophoresis, flow field-flow fractionation, fluorescence activated organelle sorting, laser capture microdissection, and dielectrophoresis. New concepts on characterization of isolated organelles included atomic force microscopy, optical tweezers combined with Raman spectroscopy, organelle sensors, flow cytometry, capillary electrophoresis, and microfluidic devices.
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Affiliation(s)
- Chad P Satori
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
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Vasileva M, Horstmann H, Geumann C, Gitler D, Kuner T. Synapsin-dependent reserveo pool of synaptic vesicles supports replenishment of the readily releasable pool under intense synaptic transmission. Eur J Neurosci 2012; 36:3005-20. [DOI: 10.1111/j.1460-9568.2012.08225.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Castorph S, Schwarz Henriques S, Holt M, Riedel D, Jahn R, Salditt T. Synaptic vesicles studied by dynamic light scattering. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2011; 34:63. [PMID: 21706281 DOI: 10.1140/epje/i2011-11063-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 05/23/2011] [Indexed: 05/31/2023]
Abstract
The size polydispersity distribution of synaptic vesicles (SVs) is characterized under quasi-physiological conditions by dynamic light scattering (DLS). Highly purified fractions of SVs obtained from rat brain still contain a small amount of larger contaminant structures, which can be quantified by DLS and further reduced by asymmetric-flow field-flow (AFFF) fractionation. The intensity autocorrelation functions g (2)(τ) recorded from these samples are analyzed by a constrained regularization method as well as by an alternative direct modeling approach. The results are in quantitative agreement with the polydispersity obtained from cryogenic electron microscopy of vitrified SVs. Next, different vesicle fusion assays based on samples composed of SVs and small unilamellar proteoliposomes with the fusion proteins syntaxin 1 and SNAP-25A are characterized by DLS. The size increase of the proteoliposomes due to SNARE-dependent fusion with SVs is quantified by DLS under quasi-physiological conditions.
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Affiliation(s)
- S Castorph
- Institut für Röntgenphysik, Georg-August-Universität Göttingen, Germany.
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Bogen IL, Risa Ø, Haug KH, Sonnewald U, Fonnum F, Walaas SI. Distinct changes in neuronal and astrocytic amino acid neurotransmitter metabolism in mice with reduced numbers of synaptic vesicles. J Neurochem 2010; 105:2524-34. [PMID: 18346203 DOI: 10.1111/j.1471-4159.2008.05344.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The relations between glutamate and GABA concentrations and synaptic vesicle density in nerve terminals were examined in an animal model with 40-50% reduction in synaptic vesicle numbers caused by inactivation of the genes encoding synapsin I and II. Concentrations and synthesis of amino acids were measured in extracts from cerebrum and a crude synaptosomal fraction by HPLC and (13)C nuclear magnetic resonance spectroscopy (NMRS), respectively. Analysis of cerebrum extracts, comprising both neurotransmitter and metabolic pools, showed decreased concentration of GABA, increased concentration of glutamine and unchanged concentration of glutamate in synapsin I and II double knockout (DKO) mice. In contrast, both glutamate and GABA concentrations were decreased in crude synaptosomes isolated from synapsin DKO mice, suggesting that the large metabolic pool of glutamate in the cerebral extracts may overshadow minor changes in the transmitter pool. (13)C NMRS studies showed that the changes in amino acid concentrations in the synapsin DKO mice were caused by decreased synthesis of GABA (20-24%) in cerebral neurons and increased synthesis of glutamine (36%) in astrocytes. In a crude synaptosomal fraction, the glutamate synthesis was reduced (24%), but this reduction could not be detected in cerebrum extracts. We suggest that lack of synaptic vesicles causes down-regulation of neuronal GABA and glutamate synthesis, with a concomitant increase in astrocytic synthesis of glutamine, in order to maintain normal neurotransmitter concentrations in the nerve terminal cytosol.
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Affiliation(s)
- Inger Lise Bogen
- Department of Biochemistry, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway.
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Influence of the spring constant of cantilevers on hydrodynamic force measurements by the colloidal probe technique. Colloids Surf A Physicochem Eng Asp 2010. [DOI: 10.1016/j.colsurfa.2009.08.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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The highly conserved synapsin domain E mediates synapsin dimerization and phospholipid vesicle clustering. Biochem J 2010; 426:55-64. [PMID: 19922412 DOI: 10.1042/bj20090762] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Synapsins are abundant SV (synaptic vesicle)-associated phosphoproteins that regulate synapse formation and function. The highly conserved C-terminal domain E was shown to contribute to several synapsin functions, ranging from formation of the SV reserve pool to regulation of the kinetics of exocytosis and SV cycling, although the molecular mechanisms underlying these effects are unknown. In the present study, we used a synthetic 25-mer peptide encompassing the most conserved region of domain E (Pep-E) to analyse the role of domain E in regulating the interactions between synapsin I and liposomes mimicking the phospholipid composition of SVs (SV-liposomes) and other pre-synaptic protein partners. In affinity-chromatography and cross-linking assays, Pep-E bound to endogenous and purified exogenous synapsin I and strongly inhibited synapsin dimerization, indicating a role in synapsin oligomerization. Consistently, Pep-E (but not its scrambled version) counteracted the ability of holo-synapsin I to bind and coat phospholipid membranes, as analysed by AFM (atomic force microscopy) topographical scanning, and significantly decreased the clustering of SV-liposomes induced by holo-synapsin I in FRET (Förster resonance energy transfer) assays, suggesting a causal relationship between synapsin oligomerization and vesicle clustering. Either Pep-E or a peptide derived from domain C was necessary and sufficient to inhibit both dimerization and vesicle clustering, indicating the participation of both domains in these activities of synapsin I. The results provide a molecular explanation for the effects of domain E in nerve terminal physiology and suggest that its effects on the size and integrity of SV pools are contributed by the regulation of synapsin dimerization and SV clustering.
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Preetz C, Hauser A, Hause G, Kramer A, Mäder K. Application of atomic force microscopy and ultrasonic resonator technology on nanoscale: Distinction of nanoemulsions from nanocapsules. Eur J Pharm Sci 2010; 39:141-51. [DOI: 10.1016/j.ejps.2009.11.009] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 11/09/2009] [Accepted: 11/25/2009] [Indexed: 11/27/2022]
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Deng L, Wu ZN, Han PZ. Effects of Different Levels of Food Restriction on Passive-Avoidance Memory and The Expression of Synapsin I in Young Mice. Int J Neurosci 2009; 119:291-304. [DOI: 10.1080/00207450802328250] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Late-onset dietary restriction compensates for age-related increase in oxidative stress and alterations of HSP 70 and synapsin 1 protein levels in male Wistar rats. Biogerontology 2009; 11:197-209. [PMID: 19609710 DOI: 10.1007/s10522-009-9240-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2009] [Accepted: 06/30/2009] [Indexed: 12/17/2022]
Abstract
Numerous reports implicate increased oxidative stress in the functional and structural changes occurring in the brain and other organs as a part of the normal aging process. Dietary restriction (DR) has long been shown to be life-prolonging intervention in several species. This study was aimed to assess the potential efficacy of late-onset short term DR when initiated in 21 months old male wistar rats for 3 months on the antioxidant defense system and lipid peroxidation, cellular stress response protein HSP 70 and synaptic marker protein synapsin 1 in discrete brain regions such as cortex, hypothalamus, and hippocampus as well as liver, kidney and heart from 24 month old rats. Age-associated decline in activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione, and elevated levels of lipid peroxidation was observed in brain and peripheral organ as well as increased expression of HSP 70 and reduction in synapsin 1 was observed in brain studied. Late-onset short term DR was effective in partially restoring the antioxidant status and in decreasing lipid peroxidation level as well as enhancing the expression of HSP 70 and synapsin 1 in aged rats. Late onset short term DR also prevented age-related neurodegeneration as revealed by Fluoro-Jade B staining in hippocampus and cortex regions of rat brain. Thus our current results suggest that DR initiated even in old age has the potential to improve age related decline in body functions.
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The importance of synapsin I and II for neurotransmitter levels and vesicular storage in cholinergic, glutamatergic and GABAergic nerve terminals. Neurochem Int 2009; 55:13-21. [DOI: 10.1016/j.neuint.2009.02.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 02/14/2009] [Accepted: 02/16/2009] [Indexed: 11/20/2022]
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Docking and fusion of synaptic vesicles in cell-free model system of exocytosis. Neurochem Int 2008; 53:401-7. [DOI: 10.1016/j.neuint.2008.09.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 08/01/2008] [Accepted: 09/18/2008] [Indexed: 10/21/2022]
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Owe SG, Jensen V, Evergren E, Ruiz A, Shupliakov O, Kullmann DM, Storm-Mathisen J, Walaas SI, Hvalby Ø, Bergersen LH. Synapsin- and actin-dependent frequency enhancement in mouse hippocampal mossy fiber synapses. Cereb Cortex 2008; 19:511-23. [PMID: 18550596 PMCID: PMC2638812 DOI: 10.1093/cercor/bhn101] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The synapsin proteins have different roles in excitatory and inhibitory synaptic terminals. We demonstrate a differential role between types of excitatory terminals. Structural and functional aspects of the hippocampal mossy fiber (MF) synapses were studied in wild-type (WT) mice and in synapsin double-knockout mice (DKO). A severe reduction in the number of synaptic vesicles situated more than 100 nm away from the presynaptic membrane active zone was found in the synapsin DKO animals. The ultrastructural level gave concomitant reduction in F-actin immunoreactivity observed at the periactive endocytic zone of the MF terminals. Frequency facilitation was normal in synapsin DKO mice at low firing rates (approximately 0.1 Hz) but was impaired at firing rates within the physiological range (approximately 2 Hz). Synapses made by associational/commissural fibers showed comparatively small frequency facilitation at the same frequencies. Synapsin-dependent facilitation in MF synapses of WT mice was attenuated by blocking F-actin polymerization with cytochalasin B in hippocampal slices. Synapsin III, selectively seen in MF synapses, is enriched specifically in the area adjacent to the synaptic cleft. This may underlie the ability of synapsin III to promote synaptic depression, contributing to the reduced frequency facilitation observed in the absence of synapsins I and II.
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Affiliation(s)
- Simen G Owe
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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