101
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Slater CR. The functional organization of motor nerve terminals. Prog Neurobiol 2015; 134:55-103. [DOI: 10.1016/j.pneurobio.2015.09.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 08/28/2015] [Accepted: 09/05/2015] [Indexed: 12/19/2022]
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102
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Midorikawa M, Sakaba T. Imaging Exocytosis of Single Synaptic Vesicles at a Fast CNS Presynaptic Terminal. Neuron 2015; 88:492-8. [DOI: 10.1016/j.neuron.2015.09.047] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 09/08/2015] [Accepted: 09/23/2015] [Indexed: 02/02/2023]
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103
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Yang X, Bognar J, He T, Mohammed M, Niespodziany I, Wolff C, Esguerra M, Rothman SM, Dubinsky JM. Brivaracetam augments short-term depression and slows vesicle recycling. Epilepsia 2015; 56:1899-909. [PMID: 26515103 DOI: 10.1111/epi.13223] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2015] [Indexed: 12/01/2022]
Abstract
OBJECTIVE Brivaracetam (BRV) decreases seizure activity in a number of epilepsy models and binds to the synaptic vesicle glycoprotein 2A (SV2A) with a higher affinity than the antiepileptic drug levetiracetam (LEV). Experiments were performed to determine if BRV acted similarly to LEV to induce or augment short-term depression (STD) under high-frequency neuronal stimulation and slow synaptic vesicle recycling. METHODS Electrophysiologic field excitatory postsynaptic potential (fEPSP) recordings were made from CA1 synapses in rat hippocampal slices loaded with BRV or LEV during intrinsic activity or with BRV actively loaded during hypertonic stimulation. STD was examined in response to 5 or 40 Hz stimulus trains. Presynaptic release of FM1-43 was visualized using two-photon microscopy to assess drug effects upon synaptic vesicle mobilization. RESULTS When hippocampal slices were incubated in 0.1-30 μm BRV or 30 μm-1 mm LEV for 3 h, the relative CA1 field EPSPs decreased over the course of a high-frequency train of stimuli more than for control slices. This STD was frequency- and concentration-dependent, with BRV being 100-fold more potent than LEV. The extent of STD depended on the length of the incubation time for both drugs. Pretreatment with LEV occluded the effects of BRV. Repeated hypertonic sucrose treatments and train stimulation successfully unloaded BRV from recycling vesicles and reversed BRVs effects on STD, as previously reported for LEV. At their maximal concentrations, BRV slowed FM1-43 release to a greater extent than in slices loaded with LEV during prolonged stimulation. SIGNIFICANCE BRV, similar to LEV, entered into recycling synaptic vesicles and produced a frequency-dependent decrement of synaptic transmission at 100-fold lower concentrations than LEV. In addition, BRV slowed synaptic vesicle mobilization more effectively than LEV, suggesting that these drugs may modify multiple functions of the synaptic vesicle protein SV2A to curb synaptic transmission and limit epileptic activity.
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Affiliation(s)
- Xiaofeng Yang
- Department of Neurology, University of Minnesota Medical School, Minneapolis, Minnesota, U.S.A.,Electrophysiology Laboratory, Xuanwu Hospital, Capital Medical University, Beijing, China.,Center of Epilepsy, Beijing Institute for Brain Disorders, Beijing, China
| | - Joseph Bognar
- Department of Neuroscience, University of Minnesota Medical School, Minneapolis, Minnesota, U.S.A
| | - Tianyu He
- Department of Neuroscience, University of Minnesota Medical School, Minneapolis, Minnesota, U.S.A
| | - Mouhari Mohammed
- Department of Neuroscience, University of Minnesota Medical School, Minneapolis, Minnesota, U.S.A
| | | | | | - Manuel Esguerra
- Department of Neuroscience, University of Minnesota Medical School, Minneapolis, Minnesota, U.S.A
| | - Steven M Rothman
- Department of Neurology, University of Minnesota Medical School, Minneapolis, Minnesota, U.S.A
| | - Janet M Dubinsky
- Department of Neuroscience, University of Minnesota Medical School, Minneapolis, Minnesota, U.S.A
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104
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Chen B, Ma XL, Geng Z, Huang SH, Zhai LK, Guo YY, Chen ZY. Up-regulation of c-Jun NH2-terminal kinase-interacting protein 3 (JIP3) contributes to BDNF-enhanced neurotransmitter release. J Neurochem 2015; 135:453-65. [PMID: 26303065 DOI: 10.1111/jnc.13226] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 06/29/2015] [Accepted: 06/30/2015] [Indexed: 12/22/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) has been implicated in the potent modulation of synaptic plasticity at both pre-synaptic and post-synaptic sites. However, the molecular mechanism underlying BDNF-mediated pre-synaptic modulation remains incompletely understood. Here, we report that BDNF treatment for over 4 h could significantly enhance the expression of c-Jun NH2-terminal kinase-interacting protein 3 (JIP3) in cultured hippocampal neurons. This enhancement could be blocked by the Trk inhibitor K252a or by a cAMP response element-binding protein (CREB) inhibitor. In addition, chromatin immunoprecipitation (ChIP) assays revealed that CREB could bind with the JIP3 promoter region and the BDNF treatment could increase this binding. Using dual-luciferase assays we further characterized the cAMP response element (CRE) site in the JIP3 promoter. Finally, we found that BDNF-increased JIP3 expression contributes to the BDNF-induced modulation of neurotransmitter release. Together, our studies reveal that in hippocampal neurons BDNF up-regulates JIP3 expression via CREB activation, which contributes to the enhancement of neurotransmitter release; thus, we have identified a novel mechanism that BDNF modulates pre-synaptic transmission.
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Affiliation(s)
- Bing Chen
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China.,Department of Pathology Tissue Bank, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Xin-Liang Ma
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Zhao Geng
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Shu-Hong Huang
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Lu-Kai Zhai
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Yun-Yun Guo
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Zhe-Yu Chen
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, CAS Center for Excellence in Brain Science, School of Medicine, Shandong University, Jinan, Shandong, China
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105
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Rey SA, Smith CA, Fowler MW, Crawford F, Burden JJ, Staras K. Ultrastructural and functional fate of recycled vesicles in hippocampal synapses. Nat Commun 2015; 6:8043. [PMID: 26292808 PMCID: PMC4560786 DOI: 10.1038/ncomms9043] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 07/11/2015] [Indexed: 12/24/2022] Open
Abstract
Efficient recycling of synaptic vesicles is thought to be critical for sustained information transfer at central terminals. However, the specific contribution that retrieved vesicles make to future transmission events remains unclear. Here we exploit fluorescence and time-stamped electron microscopy to track the functional and positional fate of vesicles endocytosed after readily releasable pool (RRP) stimulation in rat hippocampal synapses. We show that most vesicles are recovered near the active zone but subsequently take up random positions in the cluster, without preferential bias for future use. These vesicles non-selectively queue, advancing towards the release site with further stimulation in an actin-dependent manner. Nonetheless, the small subset of vesicles retrieved recently in the stimulus train persist nearer the active zone and exhibit more privileged use in the next RRP. Our findings reveal heterogeneity in vesicle fate based on nanoscale position and timing rules, providing new insights into the origins of future pool constitution.
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Affiliation(s)
- Stephanie A Rey
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | | | - Milena W Fowler
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Freya Crawford
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Jemima J Burden
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Kevin Staras
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
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106
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The Edible Red Alga Porphyra yezoensis Promotes Neuronal Survival and Cytoarchitecture in Primary Hippocampal Neurons. Cell Mol Neurobiol 2015; 36:669-82. [DOI: 10.1007/s10571-015-0247-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 07/28/2015] [Indexed: 12/13/2022]
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107
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Boesmans W, Hao MM, Vanden Berghe P. Optical Tools to Investigate Cellular Activity in the Intestinal Wall. J Neurogastroenterol Motil 2015; 21:337-51. [PMID: 26130630 PMCID: PMC4496899 DOI: 10.5056/jnm15096] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 06/10/2015] [Indexed: 12/13/2022] Open
Abstract
Live imaging has become an essential tool to investigate the coordinated activity and output of cellular networks. Within the last decade, 2 Nobel prizes have been awarded to recognize innovations in the field of imaging: one for the discovery, use, and optimization of the green fluorescent protein (2008) and the second for the development of super-resolved fluorescence microscopy (2014). New advances in both optogenetics and microscopy now enable researchers to record and manipulate activity from specific populations of cells with better contrast and resolution, at higher speeds, and deeper into live tissues. In this review, we will discuss some of the recent developments in microscope technology and in the synthesis of fluorescent probes, both synthetic and genetically encoded. We focus on how live imaging of cellular physiology has progressed our understanding of the control of gastrointestinal motility, and we discuss the hurdles to overcome in order to apply the novel tools in the field of neurogastroenterology and motility.
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Affiliation(s)
- Werend Boesmans
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for GastroIntestinal Disorders (TARGID), Department of Clinical and Experimental Medicine, University of Leuven, Leuven, Belgium
| | - Marlene M Hao
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for GastroIntestinal Disorders (TARGID), Department of Clinical and Experimental Medicine, University of Leuven, Leuven, Belgium
| | - Pieter Vanden Berghe
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for GastroIntestinal Disorders (TARGID), Department of Clinical and Experimental Medicine, University of Leuven, Leuven, Belgium
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108
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Klockow JL, Hettie KS, Secor KE, Barman DN, Glass TE. Tunable Molecular Logic Gates Designed for Imaging Released Neurotransmitters. Chemistry 2015; 21:11446-51. [DOI: 10.1002/chem.201501379] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Jessica L. Klockow
- Department of Chemistry, University of Missouri, 601 S. College Ave. Columbia, MO 65211 (USA)
| | - Kenneth S. Hettie
- Department of Chemistry, University of Missouri, 601 S. College Ave. Columbia, MO 65211 (USA)
| | - Kristen E. Secor
- Department of Chemistry, University of Missouri, 601 S. College Ave. Columbia, MO 65211 (USA)
| | - Dipti N. Barman
- Department of Chemistry, University of Missouri, 601 S. College Ave. Columbia, MO 65211 (USA)
| | - Timothy E. Glass
- Department of Chemistry, University of Missouri, 601 S. College Ave. Columbia, MO 65211 (USA)
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109
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Schneggenburger R, Rosenmund C. Molecular mechanisms governing Ca2+ regulation of evoked and spontaneous release. Nat Neurosci 2015; 18:935-41. [DOI: 10.1038/nn.4044] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/09/2015] [Indexed: 12/15/2022]
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110
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Linares-Clemente P, Rozas JL, Mircheski J, García-Junco-Clemente P, Martínez-López JA, Nieto-González JL, Vázquez ME, Pintado CO, Fernández-Chacón R. Different dynamin blockers interfere with distinct phases of synaptic endocytosis during stimulation in motoneurones. J Physiol 2015; 593:2867-88. [PMID: 25981717 DOI: 10.1113/jp270112] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Accepted: 04/29/2015] [Indexed: 01/05/2023] Open
Abstract
KEY POINTS Neurotransmitter release requires a tight coupling between synaptic vesicle exocytosis and endocytosis with dynamin being a key protein in that process. We used imaging techniques to examine the time course of endocytosis at mouse motor nerve terminals expressing synaptopHluorin, a genetically encoded reporter of the synaptic vesicle cycle. We separated two sequential phases of endocytosis taking place during the stimulation train: early and late endocytosis. Freshly released synaptic vesicle proteins are preferentially retrieved during the early phase, which is very sensitive to dynasore, an inhibitor of dynamin GTPase activity. Synaptic vesicle proteins pre-existing at the plasma membrane before the stimulation are preferentially retrieved during the late phase, which is very sensitive to myristyl trimethyl ammonium bromide (MitMAB), an inhibitor of the dynamin-phospholipid interaction. ABSTRACT Synaptic endocytosis is essential at nerve terminals to maintain neurotransmitter release by exocytosis. Here, at the neuromuscular junction of synaptopHluorin (spH) transgenic mice, we have used imaging to study exo- and endocytosis occurring simultaneously during nerve stimulation. We observed two endocytosis components, which occur sequentially during stimulation. The early component of endocytosis apparently internalizes spH molecules freshly exocytosed. This component was sensitive to dynasore, a blocker of dynamin 1 GTPase activity. In contrast, this early component was resistant to myristyl trimethyl ammonium bromide (MiTMAB), a competitive agent that blocks dynamin binding to phospholipid membranes. The late component of endocytosis is likely to internalize spH molecules that pre-exist at the plasma membrane before stimulation starts. This component was blocked by MiTMAB, perhaps by impairing the binding of dynamin or other key endocytic proteins to phospholipid membranes. Our study suggests the co-existence of two sequential synaptic endocytosis steps taking place during stimulation that are susceptible to pharmacological dissection: an initial step, preferentially sensitive to dynasore, that internalizes vesicular components immediately after they are released, and a MiTMAB-sensitive step that internalizes vesicular components pre-existing at the plasma membrane surface. In addition, we report that post-stimulus endocytosis also has several components with different sensitivities to dynasore and MiTMAB.
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Affiliation(s)
- Pedro Linares-Clemente
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
| | - José L Rozas
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
| | - Josif Mircheski
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
| | - Pablo García-Junco-Clemente
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
| | - José A Martínez-López
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
| | | | - M Eugenio Vázquez
- Departamento Química Orgánica y Centro Singular de Investigación en Química Biolóxica y Materiais Moleculares (CIQUS), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - C Oscar Pintado
- Centro Producción y Experimentación Animal, Universidad de Sevilla, Seville, Spain
| | - Rafael Fernández-Chacón
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla and Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, and CIBERNED, Seville, Spain
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111
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Watson S. Modulating mechanosensory afferent excitability by an atypical mGluR. J Anat 2015; 227:214-20. [PMID: 26053109 DOI: 10.1111/joa.12319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2015] [Indexed: 11/30/2022] Open
Abstract
Mechanotransduction by proprioceptive sensory organs is poorly understood. Evidence was recently shown that muscle spindle and hair follicle primary afferents (lanceolates) constantly release glutamate from synaptic-like vesicles (SLVs) within the terminals. The secreted glutamate activates a highly unusual metabotropic glutamate receptor (mGluR) to modulate the firing rate (spindles) and SLV recycling (lanceolates). This receptor has yet to be isolated and sequenced. To further investigate this receptor's pharmacology, ligands selective for classical mGluRs have been recently characterised for their ability to alter stretch-evoked spindle firing and SLV endocytosis in these different endings. Here, it is described how the results of these screens facilitated the development of novel compounds to be used in the process of isolating and sequencing of this non-canonical mGluR. This study shows how the compounds were tested for their ability to alter stretch-evoked afferent firing in muscle spindles and SLV endocytosis in the lanceolate endings of hair follicles to ensure they maintained their ability to bind to the receptor. For the development of novel compounds, kainate was chosen as the parent ligand due to its potency and ease of chemical modification. Novel kainate derivatives were then synthesised and tested to find potent analogues suitable for 'click-chemistry', an established technique for relatively quick, cheap, stereospecific and high-yield chemical modifications (Angewandte Chemie (International ed. in English), 40, 2001, pp2004). Of the novel kainate analogues developed, unfortunately ZCZ49 and ZCZ50 lost the ability to produce a significant change in spindle stretch-evoked firing. However, ZCZ90 was as potent as kainate, increasing firing by a similar margin at 1 μm (n = 8; P < 0.001). The addition of either a biotin or a fluorescein side group to ZCZ90, using the click-chemistry technique, did not affect the potency and hence these compounds will be used in further studies of the receptor. As well as the development of these compounds, the study found not only many similarities, but also some key differences between the two types of primary mechanosensory endings investigated. These differences must be taken into account in further study. However, they also present an intriguing opportunity for these receptors to be targeted selectively to modulate ending sensitivity as treatments for muscle spasm in multiple sclerosis and spinal cord injury, and possibly even baroreceptor firing to treat hypertension.
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Affiliation(s)
- Sonia Watson
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
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112
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Abstract
Ca(2+)-dependent synaptic vesicle recycling is essential for structural homeostasis of synapses and maintenance of neurotransmission. Although, the executive role of intrasynaptic Ca(2+) transients in synaptic vesicle exocytosis is well established, identifying the exact role of Ca(2+) in endocytosis has been difficult. In some studies, Ca(2+) has been suggested as an essential trigger required to initiate synaptic vesicle retrieval, whereas others manipulating synaptic Ca(2+) concentrations reported a modulatory role for Ca(2+) leading to inhibition or acceleration of endocytosis. Molecular studies of synaptic vesicle endocytosis, on the other hand, have consistently focused on the roles of Ca(2+)-calmodulin dependent phosphatase calcineurin and synaptic vesicle protein synaptotagmin as potential Ca(2+) sensors for endocytosis. Most studies probing the role of Ca(2+) in endocytosis have relied on measurements of synaptic vesicle retrieval after strong stimulation. Strong stimulation paradigms elicit fusion and retrieval of multiple synaptic vesicles and therefore can be affected by several factors besides the kinetics and duration of Ca(2+) signals that include the number of exocytosed vesicles and accumulation of released neurotransmitters thus altering fusion and retrieval processes indirectly via retrograde signaling. Studies monitoring single synaptic vesicle endocytosis may help resolve this conundrum as in these settings the impact of Ca(2+) on synaptic fusion probability can be uncoupled from its putative role on synaptic vesicle retrieval. Future experiments using these single vesicle approaches will help dissect the specific role(s) of Ca(2+) and its sensors in synaptic vesicle endocytosis.
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Affiliation(s)
- Jeremy Leitz
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, USA
| | - Ege T Kavalali
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, USA Department of Physiology, UT Southwestern Medical Center, Dallas, TX, USA
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113
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Motoneurons derived from induced pluripotent stem cells develop mature phenotypes typical of endogenous spinal motoneurons. J Neurosci 2015; 35:1291-306. [PMID: 25609642 DOI: 10.1523/jneurosci.2126-14.2015] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Induced pluripotent cell-derived motoneurons (iPSCMNs) are sought for use in cell replacement therapies and treatment strategies for motoneuron diseases such as amyotrophic lateral sclerosis (ALS). However, much remains unknown about the physiological properties of iPSCMNs and how they compare with endogenous spinal motoneurons or embryonic stem cell-derived motoneurons (ESCMNs). In the present study, we first used a proteomic approach and compared protein expression profiles between iPSCMNs and ESCMNs to show that <4% of the proteins identified were differentially regulated. Like ESCs, we found that mouse iPSCs treated with retinoic acid and a smoothened agonist differentiated into motoneurons expressing the LIM homeodomain protein Lhx3. When transplanted into the neural tube of developing chick embryos, iPSCMNs selectively targeted muscles normally innervated by Lhx3 motoneurons. In vitro studies showed that iPSCMNs form anatomically mature and functional neuromuscular junctions (NMJs) when cocultured with chick myofibers for several weeks. Electrophysiologically, iPSCMNs developed passive membrane and firing characteristic typical of postnatal motoneurons after several weeks in culture. Finally, iPSCMNs grafted into transected mouse tibial nerve projected axons to denervated gastrocnemius muscle fibers, where they formed functional NMJs, restored contractile force. and attenuated denervation atrophy. Together, iPSCMNs possess many of the same cellular and physiological characteristics as ESCMNs and endogenous spinal motoneurons. These results further justify using iPSCMNs as a source of motoneurons for cell replacement therapies and to study motoneuron diseases such as ALS.
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114
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Maqueshudul Haque Bhuiyan M, Mohibbullah M, Hannan MA, Hong YK, Choi JS, Choi IS, Moon IS. Undaria pinnatifida Promotes Spinogenesis and Synaptogenesis and Potentiates Functional Presynaptic Plasticity in Hippocampal Neurons. THE AMERICAN JOURNAL OF CHINESE MEDICINE 2015; 43:529-42. [PMID: 25967666 DOI: 10.1142/s0192415x15500330] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Reductions in neurotrophic factors are implicated in synaptic dysfunction in the central nervous system, but exogenous neurotrophic factors with potential effects on neuritic regeneration and synaptic reconstruction could offer therapeutic and preventive strategies for treating memory-related neurological disorders. In an earlier effort to identify natural neurotrophic agents, we found that the ethanol extract of the edible marine alga Undaria pinnatifida (UPE) had promising effects on the neuritogenesis of cultured hippocampal neurons. Here, we further investigated the ability of UPE to promote spinogenesis and synaptogenesis in primary cultures of hippocampal neurons. It was found that UPE triggered significant increase in numbers of dendritic filopodia and spines, promoted the formation of excitatory and inhibitory synapses, and potentiated synaptic transmission by increasing the sizes of reserve vesicle pools at presynaptic terminals. These findings indicate a substantial role for UPE in the morphological and functional maturation of neurons and suggest that UPE is a possible therapeutic preventative measure and treatment for neurodegenerative diseases, such as those involving cognitive disorders and memory impairments.
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115
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Ramachandran S, Alford S. Acute dissociation of lamprey reticulospinal axons to enable recording from the release face membrane of individual functional presynaptic terminals. J Vis Exp 2014:e51925. [PMID: 25350679 DOI: 10.3791/51925] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Synaptic transmission is an extremely rapid process. Action potential driven influx of Ca(2+) into the presynaptic terminal, through voltage-gated calcium channels (VGCCs) located in the release face membrane, is the trigger for vesicle fusion and neurotransmitter release. Crucial to the rapidity of synaptic transmission is the spatial and temporal synchrony between the arrival of the action potential, VGCCs and the neurotransmitter release machinery. The ability to directly record Ca(2+) currents from the release face membrane of individual presynaptic terminals is imperative for a precise understanding of the relationship between presynaptic Ca(2+) and neurotransmitter release. Access to the presynaptic release face membrane for electrophysiological recording is not available in most preparations and presynaptic Ca(2+) entry has been characterized using imaging techniques and macroscopic current measurements--techniques that do not have sufficient temporal resolution to visualize Ca(2+) entry. The characterization of VGCCs directly at single presynaptic terminals has not been possible in central synapses and has thus far been successfully achieved only in the calyx-type synapse of the chick ciliary ganglion and in rat calyces. We have successfully addressed this problem in the giant reticulospinal synapse of the lamprey spinal cord by developing an acutely dissociated preparation of the spinal cord that yields isolated reticulospinal axons with functional presynaptic terminals devoid of postsynaptic structures. We can fluorescently label and identify individual presynaptic terminals and target them for recording. Using this preparation, we have characterized VGCCs directly at the release face of individual presynaptic terminals using immunohistochemistry and electrophysiology approaches. Ca(2+) currents have been recorded directly at the release face membrane of individual presynaptic terminals, the first such recording to be carried out at central synapses.
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Affiliation(s)
| | - Simon Alford
- Biological Sciences, University of Illinois at Chicago;
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116
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Abstract
Secretory carrier membrane protein 5 (SCAMP5), a recently identified candidate gene for autism, is brain specific and highly abundant in synaptic vesicles (SVs), but its function is currently unknown. Here, we found that knockdown (KD) of endogenous SCAMP5 by SCAMP5-specific shRNAs in cultured rat hippocampal neurons resulted in a reduction in total vesicle pool size as well as in recycling pool size, but the recycling/resting pool ratio was significantly increased. SCAMP5 KD slowed endocytosis after stimulation, but impaired it severely during strong stimulation. We also found that KD dramatically lowered the threshold of activity at which SV endocytosis became unable to compensate for the ongoing exocytosis occurring during a stimulus. Reintroducing shRNA-resistant SCAMP5 reversed these endocytic defects. Therefore, our results suggest that SCAMP5 functions during high neuronal activity when a heavy load is imposed on endocytosis. Our data also raise the possibility that the reduction in expression of SCAMP5 in autistic patients may be related to the synaptic dysfunction observed in autism.
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117
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Jung DW, Hong YJ, Kim SY, Kim WH, Seo S, Lee JE, Shen H, Kim YC, Williams DR. 5-Nitro-5'hydroxy-indirubin-3'oxime is a novel inducer of somatic cell transdifferentiation. Arch Pharm (Weinheim) 2014; 347:806-18. [PMID: 25363410 DOI: 10.1002/ardp.201400223] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Revised: 07/09/2014] [Accepted: 07/11/2014] [Indexed: 12/17/2022]
Abstract
Patient-derived cell transplantation is an attractive therapy for regenerative medicine. However, this requires effective strategies to reliably differentiate patient cells into clinically useful cell types. Herein, we report the discovery that 5-nitro-5'hydroxy-indirubin-3'oxime (5'-HNIO) is a novel inducer of cell transdifferentiation. 5'-HNIO induced muscle transdifferentiation into adipogenic and osteogenic cells. 5'-HNIO was shown to inhibit aurora kinase A, which is a known cell fate regulator. 5'-HNIO produced a favorable level of transdifferentiation compared to other aurora kinase inhibitors and induced transdifferentiation across cell lineage boundaries. Significantly, 5'-HNIO treatment produced direct transdifferentiation without up-regulating potentially oncogenic induced pluripotent stem cell (iPSC) reprogramming factors. Thus, our results demonstrate that 5'-HNIO is an attractive molecular tool for cell transdifferentiation and cell fate research.
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Affiliation(s)
- Da-Woon Jung
- New Drug Targets Laboratory, School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
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Than NG, Balogh A, Romero R, Kárpáti E, Erez O, Szilágyi A, Kovalszky I, Sammar M, Gizurarson S, Matkó J, Závodszky P, Papp Z, Meiri H. Placental Protein 13 (PP13) - A Placental Immunoregulatory Galectin Protecting Pregnancy. Front Immunol 2014; 5:348. [PMID: 25191322 PMCID: PMC4138504 DOI: 10.3389/fimmu.2014.00348] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/08/2014] [Indexed: 12/16/2022] Open
Abstract
Galectins are glycan-binding proteins that regulate innate and adaptive immune responses, and some confer maternal-fetal immune tolerance in eutherian mammals. A chromosome 19 cluster of galectins has emerged in anthropoid primates, species with deep placentation and long gestation. Three of the five human cluster galectins are solely expressed in the placenta, where they may confer additional immunoregulatory functions to enable deep placentation. One of these is galectin-13, also known as Placental Protein 13 (PP13). It has a "jelly-roll" fold, carbohydrate-recognition domain and sugar-binding preference resembling other mammalian galectins. PP13 is predominantly expressed by the syncytiotrophoblast and released from the placenta into the maternal circulation. Its ability to induce apoptosis of activated T cells in vitro, and to divert and kill T cells as well as macrophages in the maternal decidua in situ, suggests important immune functions. Indeed, mutations in the promoter and an exon of LGALS13 presumably leading to altered or non-functional protein expression are associated with a higher frequency of preeclampsia and other obstetrical syndromes, which involve immune dysregulation. Moreover, decreased placental expression of PP13 and its low concentrations in first trimester maternal sera are associated with elevated risk of preeclampsia. Indeed, PP13 turned to be a good early biomarker to assess maternal risk for the subsequent development of pregnancy complications caused by impaired placentation. Due to the ischemic placental stress in preterm preeclampsia, there is increased trophoblastic shedding of PP13 immunopositive microvesicles starting in the second trimester, which leads to high maternal blood PP13 concentrations. Our meta-analysis suggests that this phenomenon may enable the potential use of PP13 in directing patient management near to or at the time of delivery. Recent findings on the beneficial effects of PP13 on decreasing blood pressure due to vasodilatation in pregnant animals suggest its therapeutic potential in preeclampsia.
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Affiliation(s)
- Nándor Gábor Than
- Perinatology Research Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services , Bethesda, MD, and Detroit, MI , USA ; Department of Obstetrics and Gynecology, Wayne State University School of Medicine , Detroit, MI , USA ; Maternity Private Department, Kútvölgyi Clinical Block, Semmelweis University , Budapest , Hungary ; Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences , Budapest , Hungary
| | - Andrea Balogh
- Department of Immunology, Eötvös Loránd University , Budapest , Hungary
| | - Roberto Romero
- Perinatology Research Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services , Bethesda, MD, and Detroit, MI , USA
| | - Eva Kárpáti
- Department of Immunology, Eötvös Loránd University , Budapest , Hungary
| | - Offer Erez
- Department of Obstetrics and Gynecology, Soroka University Medical Center, Ben-Gurion University of the Negev , Beer-Sheva , Israel
| | - András Szilágyi
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences , Budapest , Hungary
| | - Ilona Kovalszky
- First Department of Pathology and Experimental Cancer Research, Semmelweis University , Budapest , Hungary
| | - Marei Sammar
- Prof. Ephraim Katzir Department of Biotechnology Engineering, ORT Braude College , Karmiel , Israel
| | - Sveinbjorn Gizurarson
- Faculty of Pharmaceutical Sciences, School of Health Science, University of Iceland , Reykjavik , Iceland
| | - János Matkó
- Department of Immunology, Eötvös Loránd University , Budapest , Hungary
| | - Péter Závodszky
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences , Budapest , Hungary
| | - Zoltán Papp
- Maternity Private Department, Kútvölgyi Clinical Block, Semmelweis University , Budapest , Hungary
| | - Hamutal Meiri
- TeleMarpe Ltd. , Tel Aviv , Israel ; Hylabs Ltd. , Rehovot , Israel
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119
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Kim GH, Halder D, Park J, Namkung W, Shin I. Imidazole-Based Small Molecules that Promote Neurogenesis in Pluripotent Cells. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201404871] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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120
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Kim GH, Halder D, Park J, Namkung W, Shin I. Imidazole-Based Small Molecules that Promote Neurogenesis in Pluripotent Cells. Angew Chem Int Ed Engl 2014; 53:9271-4. [DOI: 10.1002/anie.201404871] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Indexed: 11/06/2022]
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121
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Leon-Pinzon C, Cercós MG, Noguez P, Trueta C, De-Miguel FF. Exocytosis of serotonin from the neuronal soma is sustained by a serotonin and calcium-dependent feedback loop. Front Cell Neurosci 2014; 8:169. [PMID: 25018697 PMCID: PMC4072984 DOI: 10.3389/fncel.2014.00169] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 06/02/2014] [Indexed: 11/25/2022] Open
Abstract
The soma of many neurons releases large amounts of transmitter molecules through an exocytosis process that continues for hundreds of seconds after the end of the triggering stimulus. Transmitters released in this way modulate the activity of neurons, glia and blood vessels over vast volumes of the nervous system. Here we studied how somatic exocytosis is maintained for such long periods in the absence of electrical stimulation and transmembrane Ca(2+) entry. Somatic exocytosis of serotonin from dense core vesicles could be triggered by a train of 10 action potentials at 20 Hz in Retzius neurons of the leech. However, the same number of action potentials produced at 1 Hz failed to evoke any exocytosis. The 20-Hz train evoked exocytosis through a sequence of intracellular Ca(2+) transients, with each transient having a different origin, timing and intracellular distribution. Upon electrical stimulation, transmembrane Ca(2+) entry through L-type channels activated Ca(2+)-induced Ca(2+) release. A resulting fast Ca(2+) transient evoked an early exocytosis of serotonin from sparse vesicles resting close to the plasma membrane. This Ca(2+) transient also triggered the transport of distant clusters of vesicles toward the plasma membrane. Upon exocytosis, the released serotonin activated autoreceptors coupled to phospholipase C, which in turn produced an intracellular Ca(2+) increase in the submembrane shell. This localized Ca(2+) increase evoked new exocytosis as the vesicles in the clusters arrived gradually at the plasma membrane. In this way, the extracellular serotonin elevated the intracellular Ca(2+) and this Ca(2+) evoked more exocytosis. The resulting positive feedback loop maintained exocytosis for the following hundreds of seconds until the last vesicles in the clusters fused. Since somatic exocytosis displays similar kinetics in neurons releasing different types of transmitters, the data presented here contributes to understand the cellular basis of paracrine neurotransmission.
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Affiliation(s)
- Carolina Leon-Pinzon
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de MéxicoMéxico D.F., México
| | - Montserrat G. Cercós
- Departamento de Neurofisiología, Instituto Nacional de Psiquiatriìa Ramoìn de la Fuente MunñizMéxico D.F., México
| | - Paula Noguez
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de MéxicoMéxico D.F., México
| | - Citlali Trueta
- Departamento de Neurofisiología, Instituto Nacional de Psiquiatriìa Ramoìn de la Fuente MunñizMéxico D.F., México
| | - Francisco F. De-Miguel
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de MéxicoMéxico D.F., México
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Wu Y, O'Toole ET, Girard M, Ritter B, Messa M, Liu X, McPherson PS, Ferguson SM, De Camilli P. A dynamin 1-, dynamin 3- and clathrin-independent pathway of synaptic vesicle recycling mediated by bulk endocytosis. eLife 2014; 3:e01621. [PMID: 24963135 PMCID: PMC4107917 DOI: 10.7554/elife.01621] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The exocytosis of synaptic vesicles (SVs) elicited by potent stimulation is rapidly compensated by bulk endocytosis of SV membranes leading to large endocytic vacuoles (‘bulk’ endosomes). Subsequently, these vacuoles disappear in parallel with the reappearance of new SVs. We have used synapses of dynamin 1 and 3 double knock-out neurons, where clathrin-mediated endocytosis (CME) is dramatically impaired, to gain insight into the poorly understood mechanisms underlying this process. Massive formation of bulk endosomes was not defective, but rather enhanced, in the absence of dynamin 1 and 3. The subsequent conversion of bulk endosomes into SVs was not accompanied by the accumulation of clathrin coated buds on their surface and this process proceeded even after further clathrin knock-down, suggesting its independence of clathrin. These findings support the existence of a pathway for SV reformation that bypasses the requirement for clathrin and dynamin 1/3 and that operates during intense synaptic activity. DOI:http://dx.doi.org/10.7554/eLife.01621.001 Neurons propagate electrical signals from one cell to the next using small molecules called neurotransmitters. These molecules are held inside small compartments called synaptic vesicles. Once a neuron receives an electrical stimulus, the membranes that enclose the synaptic vesicles fuse with the plasma membrane that encloses the neuron. This releases the neurotransmitters, which then trigger an electrical signal in the neighboring cell. Once the neurotransmitters are released, the vesicle membrane is rapidly reinternalized from the plasma membrane in a process called endocytosis and then recycled, ready for the next round of signal transmission. The process of synaptic vesicle membrane endocytosis and recycling has been studied extensively, and several different mechanisms by which it occurs have been identified. The best understood relies on a protein called clathrin, and is thought to be essential for nervous system function. Recently, however, a mechanism of vesicle membrane endocytosis that does not involve clathrin was identified. This mechanism, called bulk endocytosis, involves reinternalizing large regions of the cell plasma membrane to generate large compartments called vacuoles, from which new synaptic vesicles eventually form. This mechanism has been observed when neurons fire at high frequency. The cellular processes underlying bulk endocytosis are not well understood, although several studies suggest proteins called dynamins are important. Wu et al. simulated the conditions a cell experiences during high levels of activity in neurons that lacked the two major dynamins present at the synapses between neurons—dynamin 1 and dynamin 3. In these neurons, robust bulk endocytosis occurred, suggesting that these two major neuronal dynamins do not play a role in this process. Furthermore, formation of vesicles from the vacuoles generated by bulk endocytosis appeared to be clathrin-independent. These findings point to the occurrence of a pathway of synaptic vesicle recycling that bypasses the need for dynamin 1 and 3 as well as for clathrin. To reconcile these results with previously published work, Wu et al. propose that dynamins may only be required for processes that also require clathrin. But how are vesicles recycled during bulk endocytosis if dynamins are not involved? There are currently few leads to base alternative mechanisms on. Further work is required to unravel this mystery, and to provide insights into how clathrin-dependent and independent recycling processes are linked during high neuronal activity. DOI:http://dx.doi.org/10.7554/eLife.01621.002
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Affiliation(s)
- Yumei Wu
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
| | - Eileen T O'Toole
- Department of MCD Biology, University of Colorado, Boulder, United States
| | - Martine Girard
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Brigitte Ritter
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Mirko Messa
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
| | - Xinran Liu
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States
| | - Peter S McPherson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Shawn M Ferguson
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States
| | - Pietro De Camilli
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States
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123
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Wilson SA, Millard A, Lewis A, Loew LM. Monitoring membrane potential with second-harmonic generation. Cold Spring Harb Protoc 2014; 2014:643-654. [PMID: 24890213 DOI: 10.1101/pdb.prot081786] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This protocol describes the nonlinear optical phenomenon known as second-harmonic generation (SHG) and discusses its special attributes for imaging membrane-potential changes in single cells and multicellular preparations. Undifferentiated N1E-115 mouse neuroblastoma cells are used as a model cellular system for membrane electrophysiology. Styryl and naphthylstyryl dyes, also known as hemicyanines, are a class of electrochromic membrane-staining probes that have been used to monitor membrane potential by fluorescence; they also produce SHG images of cell membranes with SHG intensities that are sensitive to voltage. These experiments allow for the precise characterization of the voltage sensitivity of SHG and identification of the optimal wavelength for the incident laser fundamental light. This protocol presents the steps for the culture, staining, patching, and imaging of cells. The details of the imaging system and the measurements obtained are discussed, as are the prospects of this technology for imaging membrane potential changes in neuronal preparations.
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124
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Abstract
The 22q11 deletion syndrome (22q11DS) is the most common microdeletion syndrome in humans and presents with a complex and variable psychiatric phenotype. Patients show cognitive impairment and have a higher probability of psychiatric disorders. As much as 30% of patients with 22q11DS suffer from schizophrenia, the strongest association between any mutation and the disease. Schizophrenia is a complex psychiatric disease that affects multiple brain regions, giving rise to a constellation of seemingly unrelated symptoms including hallucinations, social withdrawal, and memory deficits. Synaptic or neuronal malfunctions within certain physiological circuits appear to be at the core of these symptoms. Understanding disease at the synaptic level requires genetic model systems where intact neural circuits can be interrogated for functional deficits. Because of the overlap between 22q11DS and schizophrenia, models of 22q11DS may be key genetic tools for investigating both diseases. Here we discuss the advantages of using a synaptic function approach to studying mouse models of 22q11DS, review recent findings, and discuss them in the broader context of 22q11DS and schizophrenia.
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Affiliation(s)
- Laurie R Earls
- Department of Development Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Stanislav S Zakharenko
- Department of Development Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, USA
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125
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Ultrastructural readout of functional synaptic vesicle pools in hippocampal slices based on FM dye labeling and photoconversion. Nat Protoc 2014; 9:1337-47. [DOI: 10.1038/nprot.2014.088] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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126
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Kerr M, Teasdale RD. Live imaging of endosome dynamics. Semin Cell Dev Biol 2014; 31:11-9. [PMID: 24704360 DOI: 10.1016/j.semcdb.2014.03.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 03/21/2014] [Accepted: 03/25/2014] [Indexed: 11/26/2022]
Abstract
When studying the living endosome one must first recognise that we are not studying a single discrete organelle but rather a highly dynamic interconnected network of membrane-bound compartments. Endocytosed molecules are sorted and transported through various polymorphic intracellular organelles that mature and interact with one another via fusion and fission events in a highly spatially and temporally co-ordinated manner. As such, we recognise that being a dynamic system, it must be studied in a dynamic fashion. Videomicroscopy has provided profound insights into the cell, and its use in the study of the living endosome has exemplified this supplying a unique perspective on this elusive organelle. In this review we will examine some of the seminal observations that this technology has contributed as well as survey the various assays, tools and technologies that can be applied to understanding the living endosome.
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Affiliation(s)
- Markus Kerr
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia.
| | - Rohan D Teasdale
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
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127
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Iwabuchi S, Kakazu Y, Koh JY, Goodman KM, Harata NC. Examination of synaptic vesicle recycling using FM dyes during evoked, spontaneous, and miniature synaptic activities. J Vis Exp 2014. [PMID: 24747983 DOI: 10.3791/50557] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Synaptic vesicles in functional nerve terminals undergo exocytosis and endocytosis. This synaptic vesicle recycling can be effectively analyzed using styryl FM dyes, which reveal membrane turnover. Conventional protocols for the use of FM dyes were designed for analyzing neurons following stimulated (evoked) synaptic activity. Recently, protocols have become available for analyzing the FM signals that accompany weaker synaptic activities, such as spontaneous or miniature synaptic events. Analysis of these small changes in FM signals requires that the imaging system is sufficiently sensitive to detect small changes in intensity, yet that artifactual changes of large amplitude are suppressed. Here we describe a protocol that can be applied to evoked, spontaneous, and miniature synaptic activities, and use cultured hippocampal neurons as an example. This protocol also incorporates a means of assessing the rate of photobleaching of FM dyes, as this is a significant source of artifacts when imaging small changes in intensity.
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Affiliation(s)
- Sadahiro Iwabuchi
- Department of Molecular Physiology & Biophysics, University of Iowa Carver College of Medicine
| | - Yasuhiro Kakazu
- Department of Molecular Physiology & Biophysics, University of Iowa Carver College of Medicine
| | - Jin-Young Koh
- Department of Molecular Physiology & Biophysics, University of Iowa Carver College of Medicine
| | | | - N Charles Harata
- Department of Molecular Physiology & Biophysics, University of Iowa Carver College of Medicine;
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128
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Shimoi T, Mizutani K, Kojima D, Kitamura Y, Hotta K, Ogawa H, Oka K. Identification of oscillatory firing neurons associated with locomotion in the earthworm through synapse imaging. Neuroscience 2014; 268:149-58. [PMID: 24657777 DOI: 10.1016/j.neuroscience.2014.03.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 03/06/2014] [Accepted: 03/10/2014] [Indexed: 11/16/2022]
Abstract
We used FM imaging to identify neurons that receive sensory feedback from the body wall in a circuit for octopamine (OA)-evoked rhythmic locomotion in the earthworm, Eisenia fetida. We visualized synapses in which postsynaptic neurons receive the sensory feedback, by using FM1-43 dye to label the synapses of both motor and sensory pathways that are associated with locomotion, then clearing the motor pathway synapse labeling, and finally identifying the target synapses by distinguishing physiologically functional synapses through destaining using a high-K(+) solution. A pair of synaptic regions associated with the sensory feedback was found to be located two or three cell body-widths away from the midline, between the anterior parts of the roots of the second lateral nerves (LNs) at the segmental ganglia (SGs). Using conventional intracellular recording and dye loading of the cell bodies surrounding these synaptic regions, we identified a pair of bilateral neurons with cell bodies larger than those of other cells in these regions, and named them "Oscillatory firing neurons Projecting to Peripheral nerves" (OPPs). These had a bipolar shape and projected neurites to the ipsilateral first and third LNs, fired rhythmically, and had a burst timing synchronized with the motor pattern bursts from the ipsilateral first LNs. Current injection into an OPP caused firing in the ipsilateral first LNs, supporting the hypothesis that OPPs functionally project to the peripheral nerves. OPPs also sent neurites to the adjacent anterior and posterior SGs, suggesting connections with the adjacent segments. We conclude that FM imaging can be used to identify neurons involved in specific functions, and that OPPs are the first neurons to be associated with OA-induced locomotion in the earthworm.
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Affiliation(s)
- T Shimoi
- Center for Biosciences and Informatics, Graduate School of Science and Technology, Keio University, Yokohama, Japan
| | - K Mizutani
- Department of Human and Information Science, Tokai University, Kanagawa, Japan
| | - D Kojima
- Center for Biosciences and Informatics, Graduate School of Science and Technology, Keio University, Yokohama, Japan
| | - Y Kitamura
- Department of Mathematical Sciences and Physics, College of Science and Engineering, Kanto Gakuin University, Yokohama, Japan
| | - K Hotta
- Center for Biosciences and Informatics, Graduate School of Science and Technology, Keio University, Yokohama, Japan
| | - H Ogawa
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - K Oka
- Center for Biosciences and Informatics, Graduate School of Science and Technology, Keio University, Yokohama, Japan.
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129
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Vanlandingham PA, Barmchi MP, Royer S, Green R, Bao H, Reist N, Zhang B. AP180 couples protein retrieval to clathrin-mediated endocytosis of synaptic vesicles. Traffic 2014; 15:433-50. [PMID: 24456281 PMCID: PMC4320755 DOI: 10.1111/tra.12153] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 01/16/2014] [Accepted: 01/26/2014] [Indexed: 01/01/2023]
Abstract
How clathrin-mediated endocytosis (CME) retrieves vesicle proteins into newly formed synaptic vesicles (SVs) remains a major puzzle. Besides its roles in stimulating clathrin-coated vesicle formation and regulating SV size, the clathrin assembly protein AP180 has been identified as a key player in retrieving SV proteins. The mechanisms by which AP180 recruits SV proteins are not fully understood. Here, we show that following acute inactivation of AP180 in Drosophila, SV recycling is severely impaired at the larval neuromuscular synapse based on analyses of FM 1-43 uptake and synaptic ultrastructure. More dramatically, AP180 activity is important to maintain the integrity of SV protein complexes at the plasma membrane during endocytosis. These observations suggest that AP180 normally clusters SV proteins together during recycling. Consistent with this notion, SV protein composition and distribution are altered in AP180 mutant flies. Finally, AP180 co-immunoprecipitates with SV proteins, including the vesicular glutamate transporter and neuronal synaptobrevin. These results reveal a new mode by which AP180 couples protein retrieval to CME of SVs. AP180 is also genetically linked to Alzheimer's disease. Hence, the findings of this study may provide new mechanistic insight into the role of AP180 dysfunction in Alzheimer's disease.
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130
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Abstract
FM (Fei-Mao) styryl dyes are compounds of amphiphilic character that are used for the fluorescence tracking of endocytosis and related processes, i.e., the internalization of membrane vesicles from the plasma membrane (PM) and dynamics of endomembranes. Staining with FM dyes and subsequent microscopical observations could be performed both on the tissue and cellular level. Here, we describe simple procedures for the effective FM dye staining and de-staining in root epidermal cells of Arabidopsis thaliana seedlings and suspension-cultured tobacco cells. The progression of FM dye uptake, reflected by an increased amount of the dye in the endosomal compartments, is monitored under the fluorescence microscope in a time-lapse manner. The data obtained can be used for the characterization of the rate of endocytosis and the function of components of endosomal recycling machinery.
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Affiliation(s)
- Kateřina Malínská
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, Praha 6, 165 02, Czech Republic
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131
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Gärtner A, Fornasiero EF, Valtorta F, Dotti CG. Distinct temporal hierarchies in membrane and cytoskeleton dynamics precede the morphological polarization of developing neurons. J Cell Sci 2014; 127:4409-19. [DOI: 10.1242/jcs.149815] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Final morphological polarization of neurons, with the development of a distinct axon and of several dendrites, is preceded by phases of non-polarized architecture. The earliest of these phases is that of the round neuron arising from the last mitosis. A second non polarized stage corresponds to the bipolar neuron, with two morphologically identical neurites. Both phases have their distinctive relevance in the establishment of neuronal polarity. During the round cell stage a decision is made as to where from the cell periphery a first neurite will form, thus creating the first sign of asymmetry. At the bipolar stage a decision is made as to which of the two neurites becomes the axon in neurons polarizing in vitro and the leading edge in neurons in situ. In this study we analysed cytoskeletal and membrane dynamics in cells at these two “pre-polarity” stages. By mean of time lapse imaging in dissociated hippocampal neurons and ex vivo cortical slices we show that both stages are characterized by polarized intracellular arrangements, however with distinct temporal hierarchies: polarized actin dynamics marks the site of first polarization in round cells, whereas polarized membrane dynamics precedes asymmetric growth in the bipolar stage.
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132
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Kavalali ET, Jorgensen EM. Visualizing presynaptic function. Nat Neurosci 2013; 17:10-6. [PMID: 24369372 DOI: 10.1038/nn.3578] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 10/14/2013] [Indexed: 12/15/2022]
Abstract
Synaptic communication in the nervous system is initiated by the fusion of synaptic vesicles with the presynaptic plasma membrane and subsequent neurotransmitter release. In the 1980s, this process was characterized by electron microscopy, albeit without the ability to follow processes in living cells. In the last two decades, fluorescence imaging methods have been developed that report synaptic vesicle fusion, endocytosis and recycling. These probes have provided unprecedented insight into synaptic vesicle trafficking in individual synaptic terminals and revealed heterogeneity in recycling pathways as well as synaptic vesicle populations. These methods either take advantage of uptake of fluorescent probes into recycling vesicles or exogenous expression of synaptic vesicle proteins tagged with a pH-sensitive fluorescent marker at regions facing the vesicle lumen. We provide an overview of these methods, with particular emphasis on the challenges associated with their use and the opportunities for future investigations.
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Affiliation(s)
- Ege T Kavalali
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Erik M Jorgensen
- 1] Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah, USA. [2] Department of Biology, University of Utah, Salt Lake City, Utah, USA
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133
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Dason JS, Smith AJ, Marin L, Charlton MP. Cholesterol and F-actin are required for clustering of recycling synaptic vesicle proteins in the presynaptic plasma membrane. J Physiol 2013; 592:621-33. [PMID: 24297851 DOI: 10.1113/jphysiol.2013.265447] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Synaptic vesicles (SVs) and their proteins must be recycled for sustained synaptic transmission. We tested the hypothesis that SV cholesterol is required for proper sorting of SV proteins during recycling in live presynaptic terminals. We used the reversible block of endocytosis in the Drosophila temperature-sensitive dynamin mutant shibire-ts1 to trap exocytosed SV proteins, and then examined the effect of experimental treatments on the distribution of these proteins within the presynaptic plasma membrane by confocal microscopy. SV proteins synaptotagmin, vglut and csp were clustered following SV trapping in control experiments but dispersed in samples treated with the cholesterol chelator methyl-β-cyclodextrin to extract SV cholesterol. There was accumulation of phosphatidylinositol (4,5)-bisphosphate (PIP2) in presynaptic terminals following SV trapping and this was reduced following SV cholesterol extraction. Reduced PIP2 accumulation was associated with disrupted accumulation of actin in presynaptic terminals. Similar to vesicular cholesterol extraction, disruption of actin by latrunculin A after SV proteins had been trapped on the plasma membrane resulted in the dispersal of SV proteins and prevented recovery of synaptic transmission due to impaired endocytosis following relief of the endocytic block. Our results demonstrate that vesicular cholesterol is required for aggregation of exocytosed SV proteins in the presynaptic plasma membrane and are consistent with a mechanism involving regulation of PIP2 accumulation and local actin polymerization by cholesterol. Thus, alteration of membrane or SV lipids may affect the ability of synapses to undergo sustained synaptic transmission by compromising the recycling of SV proteins.
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Affiliation(s)
- Jeffrey S Dason
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.
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134
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MacDougall MJ, Fine A. The expression of long-term potentiation: reconciling the preists and the postivists. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130135. [PMID: 24298138 DOI: 10.1098/rstb.2013.0135] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Long-term potentiation (LTP) of excitatory synaptic transmission in the hippocampus has been investigated in great detail over the past 40 years. Where and how LTP is actually expressed, however, remain controversial issues. Considerable evidence has been offered to support both pre- and postsynaptic contributions to LTP expression. Though it is widely held that postsynaptic expression mechanisms are the primary contributors to LTP expression, evidence for that conclusion is amenable to alternative explanations. Here, we briefly review some key contributions to the 'locus' debate and describe data that support a dominant role for presynaptic mechanisms. Recognition of the state-dependency of expression mechanisms, and consideration of the consequences of the spatial relationship between postsynaptic glutamate receptors and presynaptic vesicular release sites, lead to a model that may reconcile views from both sides of the synapse.
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Affiliation(s)
- Matthew J MacDougall
- Department of Physiology and Biophysics, Dalhousie University Faculty of Medicine, , Halifax, Nova Scotia, Canada , B3H 4R2
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135
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Abstract
Recent evidence suggests that endocytosis, not exocytosis, can be rate limiting for neurotransmitter release at excitatory CNS synapses during sustained activity and therefore may be a principal determinant of synaptic fatigue. At low stimulation frequencies, the probability of synaptic release is linked to the probability of synaptic retrieval such that evoked release results in proportional retrieval even for release of single synaptic vesicles. The exact mechanism by which the retrieval rates are coupled to release rates, known as compensatory endocytosis, remains unknown. Here we show that inactivation of presynaptic myosin II (MII) decreases the probability of synaptic retrieval. To be able to differentiate between the presynaptic and postsynaptic functions of MII, we developed a live cell substrate patterning technique to create defined neural circuits composed of small numbers of embryonic mouse hippocampal neurons and physically isolated from the surrounding culture. Acute application of blebbistatin to inactivate MII in circuits strongly inhibited evoked release but not spontaneous release. In circuits incorporating both control and MIIB knock-out cells, loss of presynaptic MIIB function correlated with a large decrease in the amplitude of evoked release. Using activity-dependent markers FM1-43 and horseradish peroxidase, we found that MII inactivation greatly slowed vesicular replenishment of the recycling pool but did not impede synaptic release. These results indicate that MII-driven tension or actin dynamics regulate the major pathway for synaptic vesicle retrieval. Changes in retrieval rates determine the size of the recycling pool. The resulting effect on release rates, in turn, brings about changes in synaptic strength.
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136
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Yang Y, Calakos N. Presynaptic long-term plasticity. Front Synaptic Neurosci 2013; 5:8. [PMID: 24146648 PMCID: PMC3797957 DOI: 10.3389/fnsyn.2013.00008] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 09/09/2013] [Indexed: 01/01/2023] Open
Abstract
Long-term synaptic plasticity is a major cellular substrate for learning, memory, and behavioral adaptation. Although early examples of long-term synaptic plasticity described a mechanism by which postsynaptic signal transduction was potentiated, it is now apparent that there is a vast array of mechanisms for long-term synaptic plasticity that involve modifications to either or both the presynaptic terminal and postsynaptic site. In this article, we discuss current and evolving approaches to identify presynaptic mechanisms as well as discuss their limitations. We next provide examples of the diverse circuits in which presynaptic forms of long-term synaptic plasticity have been described and discuss the potential contribution this form of plasticity might add to circuit function. Finally, we examine the present evidence for the molecular pathways and cellular events underlying presynaptic long-term synaptic plasticity.
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Affiliation(s)
- Ying Yang
- Department of Pediatrics, Stanford University School of Medicine Stanford, CA, USA
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137
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Lueke K, Kaiser T, Svetlitchny A, Welzel O, Wenzel EM, Tyagarajan S, Kornhuber J, Groemer TW. Basic presynaptic functions in hippocampal neurons are not affected by acute or chronic lithium treatment. J Neural Transm (Vienna) 2013; 121:211-9. [DOI: 10.1007/s00702-013-1087-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 08/27/2013] [Indexed: 01/27/2023]
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138
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Harlow ML, Szule JA, Xu J, Jung JH, Marshall RM, McMahan UJ. Alignment of synaptic vesicle macromolecules with the macromolecules in active zone material that direct vesicle docking. PLoS One 2013; 8:e69410. [PMID: 23894473 PMCID: PMC3718691 DOI: 10.1371/journal.pone.0069410] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 06/07/2013] [Indexed: 11/18/2022] Open
Abstract
Synaptic vesicles dock at active zones on the presynaptic plasma membrane of a neuron’s axon terminals as a precondition for fusing with the membrane and releasing their neurotransmitter to mediate synaptic impulse transmission. Typically, docked vesicles are next to aggregates of plasma membrane-bound macromolecules called active zone material (AZM). Electron tomography on tissue sections from fixed and stained axon terminals of active and resting frog neuromuscular junctions has led to the conclusion that undocked vesicles are directed to and held at the docking sites by the successive formation of stable connections between vesicle membrane proteins and proteins in different classes of AZM macromolecules. Using the same nanometer scale 3D imaging technology on appropriately stained frog neuromuscular junctions, we found that ∼10% of a vesicle’s luminal volume is occupied by a radial assembly of elongate macromolecules attached by narrow projections, nubs, to the vesicle membrane at ∼25 sites. The assembly’s chiral, bilateral shape is nearly the same vesicle to vesicle, and nubs, at their sites of connection to the vesicle membrane, are linked to macromolecules that span the membrane. For docked vesicles, the orientation of the assembly’s shape relative to the AZM and the presynaptic membrane is the same vesicle to vesicle, whereas for undocked vesicles it is not. The connection sites of most nubs on the membrane of docked vesicles are paired with the connection sites of the different classes of AZM macromolecules that regulate docking, and the membrane spanning macromolecules linked to these nubs are also attached to the AZM macromolecules. We conclude that the luminal assembly of macromolecules anchors in a particular arrangement vesicle membrane macromolecules, which contain the proteins that connect the vesicles to AZM macromolecules during docking. Undocked vesicles must move in a way that aligns this arrangement with the AZM macromolecules for docking to proceed.
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Affiliation(s)
- Mark L Harlow
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California, USA
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139
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Rodrigues HA, Lima RF, Fonseca MDC, Amaral EA, Martinelli PM, Naves LA, Gomez MV, Kushmerick C, Prado MAM, Guatimosim C. Membrane cholesterol regulates different modes of synaptic vesicle release and retrieval at the frog neuromuscular junction. Eur J Neurosci 2013; 38:2978-87. [PMID: 23841903 DOI: 10.1111/ejn.12300] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 06/04/2013] [Accepted: 06/09/2013] [Indexed: 12/14/2022]
Abstract
We investigated the effects of cholesterol removal on spontaneous and KCl-evoked synaptic vesicle recycling at the frog neuromuscular junction. Cholesterol removal by methyl-β-cyclodextrin (MβCD) induced an increase in the frequency of miniature end-plate potentials (MEPPs) and spontaneous destaining of synaptic vesicles labeled with the styryl dye FM1-43. Treatment with MβCD also increased the size of MEPPs without causing significant changes in nicotinic receptor clustering. At the ultrastructural level, synaptic vesicles from nerve terminals treated with MβCD were larger than those from control. In addition, treatment with MβCD reduced the fusion of synaptic vesicles that are mobilized during KCl-evoked stimulation, but induced recycling of those vesicles that fuse spontaneously. We therefore suggest that MβCD might favor the release of vesicles that belong to a pool that is different from that involved in the KCl-evoked release. These results reveal fundamental differences in the synaptic vesicle cycle for spontaneous and evoked release, and suggest that deregulation of cholesterol affects synaptic vesicle biogenesis and increases transmitter packing.
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Affiliation(s)
- Hermann A Rodrigues
- Departamento de Morfologia, Universidade Federal de Minas Gerais, Av Antônio Carlos 6627, Belo Horizonte, MG 31270-901, Brasil
| | - Ricardo F Lima
- Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil
| | - Matheus de C Fonseca
- Departamento de Morfologia, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brasil
| | - Ernani A Amaral
- Departamento de Morfologia, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brasil
| | - Patrícia M Martinelli
- Departamento de Morfologia, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brasil
| | - Lígia A Naves
- Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil
| | - Marcus V Gomez
- Núcleo Santa Casa de Pós-Graduação, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil.,INCT Molecular Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil
| | - Christopher Kushmerick
- Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil
| | - Marco A M Prado
- Robarts Research Institute and Department of Physiology and Pharmacology and Anatomy & Cell Biology, University of Western Ontario, London, ON, Canada
| | - Cristina Guatimosim
- Departamento de Morfologia, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brasil
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140
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Mitrukhina OB, Yakovlev AV, Sitdikova GF. The effects of hydrogen sulfide on the processes of exo- and endocytosis of synaptic vesicles in the mouse motor nerve endings. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2013. [DOI: 10.1134/s1990747812050121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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141
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Yakovleva OV, Shafigullin MU, Sitdikova GF. The role of nitric oxide in the regulation of neurotransmitter release and processes of exo- and endocytosis of synaptic vesicles in mouse motor nerve endings. NEUROCHEM J+ 2013. [DOI: 10.1134/s1819712413020104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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142
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Staras K, Mikulincer D, Gitler D. Monitoring and quantifying dynamic physiological processes in live neurons using fluorescence recovery after photobleaching. J Neurochem 2013; 126:213-22. [PMID: 23496032 DOI: 10.1111/jnc.12240] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 03/12/2013] [Accepted: 03/13/2013] [Indexed: 12/27/2022]
Abstract
The direct visualization of subcellular dynamic processes is often hampered by limitations in the resolving power achievable with conventional microscopy techniques. Fluorescence recovery after photobleaching has emerged as a highly informative approach to address this challenge, permitting the quantitative measurement of the movement of small organelles and proteins in living functioning cells, and offering detailed insights into fundamental cellular phenomena of physiological importance. In recent years, its implementation has benefited from the increasing availability of confocal microscopy systems and of powerful labeling techniques based on genetically encoded fluorescent proteins or other chemical markers. In this review, we present fluorescence recovery after photobleaching and related techniques in the context of contemporary neurobiological research and discuss quantitative and semi-quantitative approaches to their interpretation.
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Affiliation(s)
- Kevin Staras
- School of Life Sciences, University of Sussex, Brighton, UK
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143
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Properties of ribbon and non-ribbon release from rod photoreceptors revealed by visualizing individual synaptic vesicles. J Neurosci 2013; 33:2071-86. [PMID: 23365244 DOI: 10.1523/jneurosci.3426-12.2013] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Vesicle release from rod photoreceptors is regulated by Ca(2+) entry through L-type channels located near synaptic ribbons. We characterized sites and kinetics of vesicle release in salamander rods by using total internal reflection fluorescence microscopy to visualize fusion of individual synaptic vesicles. A small number of vesicles were loaded by brief incubation with FM1-43 or a dextran-conjugated, pH-sensitive form of rhodamine, pHrodo. Labeled organelles matched the diffraction-limited size of fluorescent microspheres and disappeared rapidly during stimulation. Consistent with fusion, depolarization-evoked vesicle disappearance paralleled electrophysiological release kinetics and was blocked by inhibiting Ca(2+) influx. Rods maintained tonic release at resting membrane potentials near those in darkness, causing depletion of membrane-associated vesicles unless Ca(2+) entry was inhibited. This depletion of release sites implies that sustained release may be rate limited by vesicle delivery. During depolarizing stimulation, newly appearing vesicles approached the membrane at ∼800 nm/s, where they paused for ∼60 ms before fusion. With fusion, vesicles advanced ∼18 nm closer to the membrane. Release events were concentrated near ribbons, but lengthy depolarization also triggered release from more distant non-ribbon sites. Consistent with greater contributions from non-ribbon sites during lengthier depolarization, damaging the ribbon by fluorophore-assisted laser inactivation (FALI) of Ribeye caused only weak inhibition of exocytotic capacitance increases evoked by 200-ms depolarizing test steps, whereas FALI more strongly inhibited capacitance increases evoked by 25 ms steps. Amplifying release by use of non-ribbon sites when rods are depolarized in darkness may improve detection of decrements in release when they hyperpolarize to light.
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144
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Banks RW, Cahusac PMB, Graca A, Kain N, Shenton F, Singh P, Njå A, Simon A, Watson S, Slater CR, Bewick GS. Glutamatergic modulation of synaptic-like vesicle recycling in mechanosensory lanceolate nerve terminals of mammalian hair follicles. J Physiol 2013; 591:2523-40. [PMID: 23440964 PMCID: PMC3678041 DOI: 10.1113/jphysiol.2012.243659] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Our aim in the present study was to determine whether a glutamatergic modulatory system involving synaptic-like vesicles (SLVs) is present in the lanceolate ending of the mouse and rat hair follicle and, if so, to assess its similarity to that of the rat muscle spindle annulospiral ending we have described previously. Both types of endings are formed by the peripheral sensory terminals of primary mechanosensory dorsal root ganglion cells, so the presence of such a system in the lanceolate ending would provide support for our hypothesis that it is a general property of fundamental importance to the regulation of the responsiveness of the broad class of primary mechanosensory endings. We show not only that an SLV-based system is present in lanceolate endings, but also that there are clear parallels between its operation in the two types of mechanosensory endings. In particular, we demonstrate that, as in the muscle spindle: (i) FM1-43 labels the sensory terminals of the lanceolate ending, rather than the closely associated accessory (glial) cells; (ii) the dye enters and leaves the terminals primarily by SLV recycling; (iii) the dye does not block the electrical response to mechanical stimulation, in contrast to its effect on the hair cell and dorsal root ganglion cells in culture; (iv) SLV recycling is Ca2+ sensitive; and (v) the sensory terminals are enriched in glutamate. Thus, in the lanceolate sensory ending SLV recycling is itself regulated, at least in part, by glutamate acting through a phospholipase D-coupled metabotropic glutamate receptor.
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Affiliation(s)
- Robert W Banks
- University of Aberdeen, School of Medical Sciences, School of Medical Sciences, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK.
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145
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Alabi AA, Tsien RW. Perspectives on Kiss-and-Run: Role in Exocytosis, Endocytosis, and Neurotransmission. Annu Rev Physiol 2013; 75:393-422. [DOI: 10.1146/annurev-physiol-020911-153305] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- AbdulRasheed A. Alabi
- Department of Molecular and Cellular Physiology, Stanford Institute for Neuro-Innovation and Translational Neurosciences, Stanford Medical School, Stanford, California 94305;
| | - Richard W. Tsien
- Department of Physiology and Neuroscience, Center for Neural Science, NYU Neuroscience Institute, New York University, New York, NY 10016;
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146
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Bliss TVP, Collingridge GL. Expression of NMDA receptor-dependent LTP in the hippocampus: bridging the divide. Mol Brain 2013; 6:5. [PMID: 23339575 PMCID: PMC3562207 DOI: 10.1186/1756-6606-6-5] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Accepted: 12/27/2012] [Indexed: 12/17/2022] Open
Abstract
A consensus has famously yet to emerge on the locus and mechanisms underlying the expression of the canonical NMDA receptor-dependent form of LTP. An objective assessment of the evidence leads us to conclude that both presynaptic and postsynaptic expression mechanisms contribute to this type of synaptic plasticity.
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Affiliation(s)
- Tim V P Bliss
- Division of Neurophysiology, National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
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147
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A preferentially segregated recycling vesicle pool of limited size supports neurotransmission in native central synapses. Neuron 2013; 76:579-89. [PMID: 23141069 PMCID: PMC3526798 DOI: 10.1016/j.neuron.2012.08.042] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2012] [Indexed: 01/01/2023]
Abstract
At small central synapses, efficient turnover of vesicles is crucial for stimulus-driven transmission, but how the structure of this recycling pool relates to its functional role remains unclear. Here we characterize the organizational principles of functional vesicles at native hippocampal synapses with nanoscale resolution using fluorescent dye labeling and electron microscopy. We show that the recycling pool broadly scales with the magnitude of the total vesicle pool, but its average size is small (∼45 vesicles), highly variable, and regulated by CDK5/calcineurin activity. Spatial analysis demonstrates that recycling vesicles are preferentially arranged near the active zone and this segregation is abolished by actin stabilization, slowing the rate of activity-driven exocytosis. Our approach reveals a similarly biased recycling pool distribution at synapses in visual cortex activated by sensory stimulation in vivo. We suggest that in small native central synapses, efficient release of a limited pool of vesicles relies on their favored spatial positioning within the terminal.
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148
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Kisler K, Chow RH, Dominguez R. Fluorescently-Labeled Estradiol Internalization and Membrane Trafficking in Live N-38 Neuronal Cells Visualized with Total Internal Reflection Fluorescence Microscopy. ACTA ACUST UNITED AC 2013; Suppl 12. [PMID: 24353903 DOI: 10.4172/2157-7536.s12-002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Estradiol is a steroid hormone that binds and activates estradiol receptors. Activation of these receptors is known to modulate neuronal physiology and provide neuroprotection, but it is not completely understood how estradiol mediates these actions on the nervous system. Activation of a sub-population of estradiol receptor-α (ERα), originally identified as a nuclear protein, localizes to the plasma membrane and appears to be a critical step in neuroprotection against brain injury and disease. Previously we showed that estradiol stimulates the rapid and transient trafficking of plasma membrane ERα in primary hypothalamic neurons, and internalization of membrane-impermeant estradiol (E6BSA-FITC) into cortical neuron endosomes in vitro. These findings support the concept that estradiol activates and down-regulates plasma membrane ERα by triggering endocytosis. Here, we use TIRFM (total internal reflection fluorescence microscopy) to image the trafficking of E6BSA-FITC, and GFP-labeled ERα, in live cells in real time. We show that activation of plasma membrane ERs by E6BSA-FITC result in internalization of the fluorescent ligand in live N-38 neurons, an immortalized hypothalamic cell line. Pretreatment with ER antagonist ICI 182,780 decreased the number of E6BSA-FITC labeled puncta observed. We also observed in live N-38 neurons that E6BSA-FITC co-localized with FM4-64 and LysoTracker fluorescent dyes that label endosomes and lysosomes. Our results provide further evidence that plasma membrane ERα activation results in endocytosis of the receptor.
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Affiliation(s)
- Kassandra Kisler
- Zilkha Neurogenetic Institute, Department of Physiology and Biophysics, Keck School of Medicine of University of Southern California, USA
| | - Robert H Chow
- Zilkha Neurogenetic Institute, Department of Physiology and Biophysics, Keck School of Medicine of University of Southern California, USA
| | - Reymundo Dominguez
- Zilkha Neurogenetic Institute, Department of Physiology and Biophysics, Keck School of Medicine of University of Southern California, USA
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149
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Kawano H, Katsurabayashi S, Kakazu Y, Yamashita Y, Kubo N, Kubo M, Okuda H, Takasaki K, Kubota K, Mishima K, Fujiwara M, Harata NC, Iwasaki K. Long-term culture of astrocytes attenuates the readily releasable pool of synaptic vesicles. PLoS One 2012; 7:e48034. [PMID: 23110166 PMCID: PMC3482238 DOI: 10.1371/journal.pone.0048034] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 09/19/2012] [Indexed: 12/24/2022] Open
Abstract
The astrocyte is a major glial cell type of the brain, and plays key roles in the formation, maturation, stabilization and elimination of synapses. Thus, changes in astrocyte condition and age can influence information processing at synapses. However, whether and how aging astrocytes affect synaptic function and maturation have not yet been thoroughly investigated. Here, we show the effects of prolonged culture on the ability of astrocytes to induce synapse formation and to modify synaptic transmission, using cultured autaptic neurons. By 9 weeks in culture, astrocytes derived from the mouse cerebral cortex demonstrated increases in β-galactosidase activity and glial fibrillary acidic protein (GFAP) expression, both of which are characteristic of aging and glial activation in vitro. Autaptic hippocampal neurons plated on these aging astrocytes showed a smaller amount of evoked release of the excitatory neurotransmitter glutamate, and a lower frequency of miniature release of glutamate, both of which were attributable to a reduction in the pool of readily releasable synaptic vesicles. Other features of synaptogenesis and synaptic transmission were retained, for example the ability to induce structural synapses, the presynaptic release probability, the fraction of functional presynaptic nerve terminals, and the ability to recruit functional AMPA and NMDA glutamate receptors to synapses. Thus the presence of aging astrocytes affects the efficiency of synaptic transmission. Given that the pool of readily releasable vesicles is also small at immature synapses, our results are consistent with astrocytic aging leading to retarded synapse maturation.
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Affiliation(s)
- Hiroyuki Kawano
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
| | - Shutaro Katsurabayashi
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
- * E-mail: (SK); (KI)
| | - Yasuhiro Kakazu
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
| | - Yuta Yamashita
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
| | - Natsuko Kubo
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
| | - Masafumi Kubo
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
| | - Hideto Okuda
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
| | - Kotaro Takasaki
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
| | - Kaori Kubota
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
| | - Kenichi Mishima
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
- A.I.G. Collaborative Research Institute for Aging and Brain Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
| | - Michihiro Fujiwara
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
| | - N. Charles Harata
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
| | - Katsunori Iwasaki
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
- A.I.G. Collaborative Research Institute for Aging and Brain Sciences, Fukuoka University, Fukuoka, Fukuoka, Japan
- * E-mail: (SK); (KI)
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150
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Abstract
Exocytosis is a multistage process involving a merger between the vesicle and the plasma membranes, leading to the formation of a fusion pore, a channel, through which secretions are released from the vesicle to the cell exterior. A stimulus may influence the pore by either dilating it completely (full-fusion exocytosis) or mediating a reversible closure (transient exocytosis). In neurons, these transitions are short-lived and not accessible for experimentation. However, in some neuroendocrine cells, initial fusion pores may reopen several hundred times, indicating their stability. Moreover, these pores are too narrow to pass luminal molecules to the extracellular space, termed release-unproductive. However, on stimulation, their diameter dilates, initiating the release of cargo without de novo fusion pore formation. To explain the stability of the initial narrow fusion pores, anisotropic membrane constituents with non-axisymmetrical shape were proposed to accumulate in the fusion pore membrane. Although the nature of these is unclear, they may consist of lipids and proteins, including SNAREs, which may facilitate and regulate the pre- and post-fusional stages of exocytosis. In the future, a more detailed insight into the molecular control of fusion pore stabilization and regulation will generate a better understanding of fusion pore physiology in health and disease.
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