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Tonello R, Anderson WB, Davidson S, Escriou V, Yang L, Schmidt BL, Imlach WL, Bunnett NW. The contribution of endocytosis to sensitization of nociceptors and synaptic transmission in nociceptive circuits. Pain 2023; 164:1355-1374. [PMID: 36378744 PMCID: PMC10182228 DOI: 10.1097/j.pain.0000000000002826] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022]
Abstract
ABSTRACT Chronic pain involves sensitization of nociceptors and synaptic transmission of painful signals in nociceptive circuits in the dorsal horn of the spinal cord. We investigated the contribution of clathrin-dependent endocytosis to sensitization of nociceptors by G protein-coupled receptors (GPCRs) and to synaptic transmission in spinal nociceptive circuits. We determined whether therapeutic targeting of endocytosis could ameliorate pain. mRNA encoding dynamin (Dnm) 1 to 3 and adaptor-associated protein kinase 1 (AAK1), which mediate clathrin-dependent endocytosis, were localized to primary sensory neurons of dorsal root ganglia of mouse and human and to spinal neurons in the dorsal horn of the mouse spinal cord by RNAScope. When injected intrathecally to mice, Dnm and AAK1 siRNA or shRNA knocked down Dnm and AAK1 mRNA in dorsal root ganglia neurons, reversed mechanical and thermal allodynia and hyperalgesia, and normalized nonevoked behavior in preclinical models of inflammatory and neuropathic pain. Intrathecally administered inhibitors of clathrin, Dnm, and AAK1 also reversed allodynia and hyperalgesia. Disruption of clathrin, Dnm, and AAK1 did not affect normal motor functions of behaviors. Patch clamp recordings of dorsal horn neurons revealed that Dnm1 and AAK1 disruption inhibited synaptic transmission between primary sensory neurons and neurons in lamina I/II of the spinal cord dorsal horn by suppressing release of synaptic vesicles from presynaptic primary afferent neurons. Patch clamp recordings from dorsal root ganglion nociceptors indicated that Dnm siRNA prevented sustained GPCR-mediated sensitization of nociceptors. By disrupting synaptic transmission in the spinal cord and blunting sensitization of nociceptors, endocytosis inhibitors offer a therapeutic approach for pain treatment.
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Affiliation(s)
- Raquel Tonello
- Department of Molecular Pathobiology, Department of Neuroscience and Physiology, Neuroscience Institute, New York University, New York, NY 10010, USA
- Pain Research Center, New York University
| | - Wayne B. Anderson
- Department of Physiology and Monash Biomedicine Discovery Institute, Monash University, VIC 3800, Australia
| | - Steve Davidson
- Department of Anesthesiology, College of Medicine, University of Cincinnati, Cincinnati, USA
| | | | - Lei Yang
- NYU Dentistry Translational Research Center, New York University College of Dentistry, New York, NY 10010, USA
| | - Brian L. Schmidt
- Department of Molecular Pathobiology, Department of Neuroscience and Physiology, Neuroscience Institute, New York University, New York, NY 10010, USA
- Pain Research Center, New York University
- NYU Dentistry Translational Research Center, New York University College of Dentistry, New York, NY 10010, USA
| | - Wendy L. Imlach
- Department of Physiology and Monash Biomedicine Discovery Institute, Monash University, VIC 3800, Australia
| | - Nigel W. Bunnett
- Department of Molecular Pathobiology, Department of Neuroscience and Physiology, Neuroscience Institute, New York University, New York, NY 10010, USA
- Pain Research Center, New York University
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2
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Ghosh D, Nieves-Cintrón M, Tajada S, Brust-Mascher I, Horne MC, Hell JW, Dixon RE, Santana LF, Navedo MF. Dynamic L-type Ca V1.2 channel trafficking facilitates Ca V1.2 clustering and cooperative gating. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:1341-1355. [PMID: 29959960 PMCID: PMC6407617 DOI: 10.1016/j.bbamcr.2018.06.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 06/22/2018] [Accepted: 06/26/2018] [Indexed: 11/21/2022]
Abstract
L-type CaV1.2 channels are key regulators of gene expression, cell excitability and muscle contraction. CaV1.2 channels organize in clusters throughout the plasma membrane. This channel organization has been suggested to contribute to the concerted activation of adjacent CaV1.2 channels (e.g. cooperative gating). Here, we tested the hypothesis that dynamic intracellular and perimembrane trafficking of CaV1.2 channels is critical for formation and dissolution of functional channel clusters mediating cooperative gating. We found that CaV1.2 moves in vesicular structures of circular and tubular shape with diverse intracellular and submembrane trafficking patterns. Both microtubules and actin filaments are required for dynamic movement of CaV1.2 vesicles. These vesicles undergo constitutive homotypic fusion and fission events that sustain CaV1.2 clustering, channel activity and cooperative gating. Our study suggests that CaV1.2 clusters and activity can be modulated by diverse and unique intracellular and perimembrane vesicular dynamics to fine-tune Ca2+ signals.
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Affiliation(s)
- Debapriya Ghosh
- Department of Pharmacology, School of Medicine, One Shields Avenue, University of California, Davis, CA 95616, USA
| | - Madeline Nieves-Cintrón
- Department of Pharmacology, School of Medicine, One Shields Avenue, University of California, Davis, CA 95616, USA
| | - Sendoa Tajada
- Department of Physiology & Membrane Biology, School of Medicine, One Shields Avenue, University of California, Davis, CA 95616, USA
| | - Ingrid Brust-Mascher
- Advanced Imaging Facility, School of Veterinary Medicine, One Shields Avenue, University of California, Davis, CA 95616, USA
| | - Mary C Horne
- Department of Pharmacology, School of Medicine, One Shields Avenue, University of California, Davis, CA 95616, USA
| | - Johannes W Hell
- Department of Pharmacology, School of Medicine, One Shields Avenue, University of California, Davis, CA 95616, USA
| | - Rose E Dixon
- Department of Physiology & Membrane Biology, School of Medicine, One Shields Avenue, University of California, Davis, CA 95616, USA
| | - Luis F Santana
- Department of Physiology & Membrane Biology, School of Medicine, One Shields Avenue, University of California, Davis, CA 95616, USA
| | - Manuel F Navedo
- Department of Pharmacology, School of Medicine, One Shields Avenue, University of California, Davis, CA 95616, USA.
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3
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Stimulation of synapse formation between stem cell-derived neurons and native brainstem auditory neurons. Sci Rep 2017; 7:13843. [PMID: 29062015 PMCID: PMC5653851 DOI: 10.1038/s41598-017-13764-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 09/11/2017] [Indexed: 01/05/2023] Open
Abstract
Integration of stem cell-derived cells into native cellular environment remains a challenge in the field. This study developed novel methods to co-culture neural stem cell-derived spiral ganglion-like neurons (ScNs) and mouse auditory cochlear nucleus (CN) neurons to understand whether ScNs of the peripheral nervous system (PNS) synapse with CN neurons of the central nervous system (CNS). ScNs were obtained from neural stem cells that were derived from transgenic mouse pre-labeled with enhanced green fluorescent protein (EGFP), whereas CN neurons were from postnatal mouse primary cultures. ScNs and CN neurons were co-cultured for 4–6 days in the absence or presence of astrocyte-conditioned medium (ACM). Class III β-tubulin (TUJ1)-expressing connections were found between ScNs and CN neurons. Expression of the synaptic vesicle marker SV2 was significantly increased along connections between ScNs and CN neurons in the presence of ACM. Immunodepletion and knockout studies indicated that thrombospodin-1 played an important role in ACM-exerted synaptogenic effects. Newly-generated synapse-like structures expressed glutamatergic marker VGluT1, pre- and post-synaptic proteins. Synaptic vesicle recycling studies suggested functional synaptic vesicle retrieval. These results reveal that stem cell-derived PNS neurons are able to form functional connections with native CNS neurons, which is critical for stem cell-based neural pathway regeneration.
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Horváth D, Tamás I, Sipos A, Darula Z, Bécsi B, Nagy D, Iván J, Erdődi F, Lontay B. Myosin phosphatase and RhoA-activated kinase modulate neurotransmitter release by regulating SNAP-25 of SNARE complex. PLoS One 2017; 12:e0177046. [PMID: 28486561 PMCID: PMC5423623 DOI: 10.1371/journal.pone.0177046] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/23/2017] [Indexed: 11/19/2022] Open
Abstract
Reversible phosphorylation of neuronal proteins plays an important role in the regulation of neurotransmitter release. Myosin phosphatase holoenzyme (MP) consists of a protein phosphatase-1 (PP1) catalytic subunit (PP1c) and a regulatory subunit, termed myosin phosphatase targeting subunit (MYPT1). The primary function of MP is to regulate the phosphorylation level of contractile proteins; however, recent studies have shown that MP is localized to neurons, and is also involved in the mediation of neuronal processes. Our goal was to investigate the effect of RhoA-activated kinase (ROK) and MP on the phosphorylation of one potential neuronal substrate, the synaptosomal-associated protein of 25 kDa (SNAP-25). SNAP-25 is a member of the SNARE (soluble N-ethylmaleimide sensitive factor attachment protein receptor) complex, along with synaptobrevin and syntaxin, and the primary role of SNAP25 is to mediate vesicle fusion. We showed that MYPT1 interacts with SNAP-25, as revealed by immunoprecipitation and surface plasmon resonance based binding studies. Mass spectrometry analysis and in vitro phosphorylation/dephosphorylation assays demonstrated that ROK phosphorylates, while MP dephosphorylates, SNAP-25 at Thr138. Silencing MYPT1 in B50 neuroblastoma cells increased phosphorylation of SNAP-25 at Thr138. Inhibition of PP1 with tautomycetin increased, whereas inhibition of ROK by H1152, decreased the phosphorylation of SNAP-25 at Thr138 in B50 cells, in cortical synaptosomes, and in brain slices. In response to the transduction of the MP inhibitor, kinase-enhanced PP1 inhibitor (KEPI), into synaptosomes, an increase in phosphorylation of SNAP-25 and a decrease in the extent of neurotransmitter release were detected. The interaction between SNAP-25 and syntaxin increased with decreasing phosphorylation of SNAP-25 at Thr138, upon inhibition of ROK. Our data suggest that ROK/MP play a crucial role in vesicle trafficking, fusion, and neurotransmitter release by oppositely regulating the phosphorylation of SNAP-25 at Thr138.
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Affiliation(s)
- Dániel Horváth
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - István Tamás
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Adrienn Sipos
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zsuzsanna Darula
- Hungarian Academy of Sciences, Proteomics Research Group, Biological Research Centre, Szeged, Hungary
| | - Bálint Bécsi
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Dénes Nagy
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Judit Iván
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Ferenc Erdődi
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Beáta Lontay
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- * E-mail:
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Fu P, Wen Y, Xiong Y, Zhang Y, Zhang H, Xie Y, Shi Q. Abnormal Expression of FBXL20 in Refractory Epilepsy Patients and a Pilocarpine-Induced Rat Model. Neurochem Res 2016; 41:3020-3031. [PMID: 27502938 DOI: 10.1007/s11064-016-2021-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 07/08/2016] [Accepted: 07/28/2016] [Indexed: 10/21/2022]
Abstract
E3 ubiquitin ligases are important protein-modifying enzymes involved in the pathogenesis of a variety of neurodegenerative diseases. F-box and leucine-rich repeat protein 20 (FBXL20), an E3 ubiquitin ligase widely expressed in the central nervous system, plays an important role in the ubiquitin-dependent degradation of regulating synaptic membrane exocytosis 1 (RIM1), which is an important factor in the release of synaptic vesicles. FBXL20 has been associated with a variety of neurodegenerative diseases; thus, we hypothesized that FBXL20 is involved in the development of epilepsy. Herein, we used immunofluorescence staining, immunohistochemistry and western blotting to determine the expression pattern of FBXL20 in temporal lobe epilepsy patients and pilocarpine-induced epilepsy animal models. We also injected SD rats with lentivirus-vector mediated overexpression of FBXL20. The results showed that FBXL20 is expressed in the membrane and the cytoplasm of cortical neurons, and overexpression of FBXL20 decreased the onset level of spontaneous seizure, the frequency and duration of seizures. Additionally, FBXL20 protein level was decreased but RIM1 protein level was increased in the epileptic group compared with the LV-FBXL20 and LV-GFP group. These findings in humans were consistent with the results from a pilocarpine-induced animal model of chronic epilepsy. Thus, abnormal expression of FBXL20 might play an important role in the development of epilepsy.
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Affiliation(s)
- Pengfei Fu
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - YueTao Wen
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Yan Xiong
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Yanke Zhang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Haiyang Zhang
- Department of Pediatric Intensive Care Unit, West China Second University Hospital, Sichuan University, Chengdu, 610000, China
| | - Yanfeng Xie
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Quanhong Shi
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China.
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Caesar M, Felk S, Aasly JO, Gillardon F. Changes in actin dynamics and F-actin structure both in synaptoneurosomes of LRRK2(R1441G) mutant mice and in primary human fibroblasts of LRRK2(G2019S) mutation carriers. Neuroscience 2014; 284:311-324. [PMID: 25301747 DOI: 10.1016/j.neuroscience.2014.09.070] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 09/01/2014] [Accepted: 09/02/2014] [Indexed: 12/13/2022]
Abstract
Converging evidence suggests that the Parkinson's disease-linked leucine-rich repeat kinase 2 (LRRK2) modulates cellular function by regulating actin dynamics. In the present study we investigate the role of LRRK2 in functional synaptic terminals of adult LRRK2-knockout and LRRK2(R1441G)-transgenic mice as well as in primary fibroblasts of LRRK2(G2019S) mutation carriers. We show that lack of LRRK2 decreases and overexpression of mutant LRRK2 age-dependently increases the effect of the actin depolymerizing agent Latrunculin A (LatA) on the synaptic cytoskeleton. Similarly, endogenous mutant LRRK2 increases sensitivity to LatA in primary fibroblasts. Under basal conditions however, these fibroblasts show an increase in F-actin bundles and a decrease in filopodial length which can be rescued by LatA treatment. Our data suggest that LRRK2 alters actin dynamics and F-actin structure both in brain neurons and skin fibroblasts. We hypothesize that increased F-actin bundling represents a compensatory mechanism to protect F-actin from the depolymerizing effect of mutant LRRK2 under basal conditions. Our data further indicate that LRRK2-dependent changes in the cytoskeleton might have functional consequences on postsynaptic NMDA receptor localization.
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Affiliation(s)
- M Caesar
- Boehringer Ingelheim Pharma GmbH & Co. KG, CNS Diseases Research, Biberach an der Riss, Germany.
| | - S Felk
- Boehringer Ingelheim Pharma GmbH & Co. KG, CNS Diseases Research, Biberach an der Riss, Germany
| | - J O Aasly
- St. Olav's University Hospital, Department of Neurology, Trondheim, Norway
| | - F Gillardon
- Boehringer Ingelheim Pharma GmbH & Co. KG, CNS Diseases Research, Biberach an der Riss, Germany.
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7
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Alhebshi A, Odawara A, Gotoh M, Suzuki I. Thymoquinone protects cultured hippocampal and human induced pluripotent stem cells-derived neurons against α-synuclein-induced synapse damage. Neurosci Lett 2014; 570:126-31. [DOI: 10.1016/j.neulet.2013.09.049] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 09/18/2013] [Accepted: 09/19/2013] [Indexed: 11/30/2022]
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Abstract
Synaptic vesicle recycling is one of the best-studied cellular pathways. Many of the proteins involved are known, and their interactions are becoming increasingly clear. However, as for many other pathways, it is still difficult to understand synaptic vesicle recycling as a whole. While it is generally possible to point out how synaptic reactions take place, it is not always easy to understand what triggers or controls them. Also, it is often difficult to understand how the availability of the reaction partners is controlled: how the reaction partners manage to find each other in the right place, at the right time. I present here an overview of synaptic vesicle recycling, discussing the mechanisms that trigger different reactions, and those that ensure the availability of reaction partners. A central argument is that synaptic vesicles bind soluble cofactor proteins, with low affinity, and thus control their availability in the synapse, forming a buffer for cofactor proteins. The availability of cofactor proteins, in turn, regulates the different synaptic reactions. Similar mechanisms, in which one of the reaction partners buffers another, may apply to many other processes, from the biogenesis to the degradation of the synaptic vesicle.
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Affiliation(s)
- Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen European Neuroscience Institute, Göttingen, Germany
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9
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Peng H, Kang N, Xu J, Stanton PK, Kang J. Two distinct modes of exocytotic fusion pore expansion in large astrocytic vesicles. J Biol Chem 2013; 288:16872-16881. [PMID: 23620588 DOI: 10.1074/jbc.m113.468231] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Formation of the fusion pore is a central question for regulated exocytosis by which secretory cells release neurotransmitters or hormones. Here, by dynamically monitoring exocytosis of large vesicles (2-7 μM) in astrocytes with two-photon microscopy imaging, we found that the exocytotic fusion pore was generated from the SNARE-dependent fusion at a ring shape of the docked plasma-vesicular membrane and the movement of a fusion-produced membrane fragment. We observed two modes of fragment movements, 1) a shift fragment that shifted to expand the fusion pore and 2) a fall-in fragment that fell into the collapsed vesicle to expand the fusion pore. Shift and fall-in modes are associated with full and partial collapses of large vesicles, respectively. The astrocytic marker, sulforhodamine 101, stained the fusion-produced membrane fragment more brightly than FM 1-43. Sulforhodamine 101 imaging showed that double fusion pores could simultaneously occur in a single vesicle (16% of large vesicles) to accelerate discharge of vesicular contents. Electron microscopy of large astrocytic vesicles showed shift and fall-in membrane fragments. Two modes of fusion pore formation demonstrate a novel mechanism underlying fusion pore expansion and provide a new explanation for full and partial collapses of large secretory vesicles.
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Affiliation(s)
- Hong Peng
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York 10595
| | - Ning Kang
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York 10595
| | - Jun Xu
- East Hospital, Tongji University School of Medicine, Shanghai 200120, China.
| | - Patric K Stanton
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York 10595
| | - Jian Kang
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York 10595.
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10
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Alhebshi A, Gotoh M, Suzuki I. Thymoquinone protects cultured rat primary neurons against amyloid β-induced neurotoxicity. Biochem Biophys Res Commun 2013; 433:362-7. [DOI: 10.1016/j.bbrc.2012.11.139] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 11/06/2012] [Indexed: 01/02/2023]
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11
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Lemeshchenko VV, Pekun TG, Waseem TV, Fedorovich SV. Y-27632 induces calcium-independent glutamate release in rat brain synaptosomes by a mechanism distinct from exocytosis. Biophysics (Nagoya-shi) 2012. [DOI: 10.1134/s0006350912030116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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12
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DiGiovanni J, Sun T, Sheng ZH. Characterizing synaptic vesicle proteins using synaptosomal fractions and cultured hippocampal neurons. CURRENT PROTOCOLS IN NEUROSCIENCE 2012; Chapter 2:Unit 2.7.1-22. [PMID: 22470148 PMCID: PMC4532315 DOI: 10.1002/0471142301.ns0207s59] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cloning and characterization of synaptic vesicle proteins and their binding counterparts on the presynaptic plasma membrane have greatly advanced our understanding of the molecular mechanisms involved in the synaptic vesicle cycle and neurotransmitter release. This unit discusses multidisciplinary approaches to characterize proteins from synaptosome-enriched subcellular fractions and localize them within cultured neurons. The first approach regroups methods used to isolate synaptic vesicles from rat brain synaptosomal preparations, allowing for specific biochemical investigation of synaptic vesicle proteins. The second is a detailed procedure for pre-embedding immunogold staining and electron microscopic observation, which permits the morphological identification of proteins in individual vesicles at intact synapses. Additionally, this chapter proposes methods for light microscopic examination of hippocampal neurons. It includes procedures for embryonic and postnatal hippocampal neuron culture and describes an immunocytochemical staining protocol used to investigate synaptic vesicle protein localization with respect to other proteins or subcellular structures.
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Affiliation(s)
- Jerome DiGiovanni
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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13
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Conservation and innovation in Tetrahymena membrane traffic: proteins, lipids, and compartments. Methods Cell Biol 2012; 109:141-75. [PMID: 22444145 DOI: 10.1016/b978-0-12-385967-9.00006-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The past decade has seen a significant expansion in our understanding of membrane traffic in Tetrahymena thermophila, facilitated by the development of new experimental tools and by the availability of the macronuclear genome sequence. Here we review studies on multiple pathways of uptake and secretion, as well as work on metabolism of membrane lipids. We discuss evidence for conservation versus innovation in the mechanisms used in ciliates compared with those in other eukaryotic lineages, and raise the possibility that existing gene expression databases can be exploited to analyze specific pathways of membrane traffic in these cells.
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14
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Frequency-dependent modes of synaptic vesicle endocytosis and exocytosis at adult mouse neuromuscular junctions. J Neurosci 2011; 31:1093-105. [PMID: 21248134 DOI: 10.1523/jneurosci.2800-10.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During locomotion, adult rodent lumbar motoneurons fire in high-frequency (80-100 Hz) 1-2 s bursts every several seconds, releasing between 10,000 and 20,000 vesicles per burst. The estimated total vesicle pool size indicates that all vesicles would be used within 30 s; thus, a mechanism for rapid endocytosis and vesicle recycling is necessary to maintain effective transmission and motor behavior. However, whether such rapid recycling exists at mouse neuromuscular junctions (NMJs) or how it is regulated has been unclear. Here, we show that much less FM1-43 dye is lost per stimulus with 100 Hz stimulation than with 10 Hz stimulation even when the same number of vesicles undergo exocytosis. Electrophysiological data using folimycin show this lesser amount of dye loss is caused in part by the rapid reuse of vesicles. We showed previously that a myosin light chain kinase (MLCK)-myosin II pathway was required for effective transmission at 100 Hz. Here, we confirm the activation of MLCK, based on increased nerve terminal phospho-MLC immunostaining, with 100 Hz but not with 10 Hz stimulation. We further demonstrate that activation of MLCK, by increased extracellular Ca(2+), by PKC (protein kinase C) activation, or by a MLCK agonist peptide, reduces the amount of dye lost even with 10 Hz stimulation. MLCK activation at 10 Hz also resulted in more vesicles being rapidly reused. Thus, MLCK activation by 100 Hz stimulation switches the mechanism of vesicle cycling to a rapid-reuse mode and is required to sustain effective transmission in adult mouse NMJs.
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15
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Li P, Katirai F, Zheng F, Gong F. Recycling and reutilization of cytotoxic molecules, a new type of energy conservation of NK cells? Med Hypotheses 2010; 76:293-5. [PMID: 21075541 DOI: 10.1016/j.mehy.2010.10.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 10/12/2010] [Accepted: 10/13/2010] [Indexed: 10/18/2022]
Abstract
Natural killer (NK) cells play critical roles in defense against tumors and viral infections. They exert their cytotoxic functions through the secretion of granules containing cytotoxic molecules, such as perforin and granzymes. These cytotoxic molecules are stored within dual-functional organelles, known as secretory lysosomes. Target cell recognition induces the formation of an "immunological synapse", between the NK cell and its target, into which cytotoxic granules release their contents. However the post-exocytosis regulation of the process is still largely unknown. Recent research and the data accumulated therefrom lead to new hypotheses that suggest that, not unlike synaptic vesicle recycling in neuronal terminals, NK cells also recycle not just their secretory lysosome membranes but their correlated cytotoxic molecules (perforin and granzymes). The newly endocytosed vesicles are used to replenish the "reserve pool" of vesicles for continued NK cell serial killings. These hypotheses, if proved to be correct, will significantly improve our understanding of NK cell cytotoxicity mechanisms and might even suggest new NK cell-based therapies that rely on NK serial killing abilities for overcoming tumors.
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Affiliation(s)
- Pan Li
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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16
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Odell LR, Howan D, Gordon CP, Robertson MJ, Chau N, Mariana A, Whiting AE, Abagyan R, Daniel JA, Gorgani NN, Robinson PJ, McCluskey A. The pthaladyns: GTP competitive inhibitors of dynamin I and II GTPase derived from virtual screening. J Med Chem 2010; 53:5267-80. [PMID: 20575553 DOI: 10.1021/jm100442u] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the development of a homology model for the GTP binding domain of human dynamin I based on the corresponding crystal structure of Dictyostelium discoidum dynamin A. Virtual screening identified 2-[(2-biphenyl-2-yl-1,3-dioxo-2,3-dihydro-1H-isoindole-5-carbonyl)amino]-4-chlorobenzoic acid (1) as a approximately 170 microM potent inhibitor. Homology modeling- and focused library-led synthesis resulted in development of a series of active compounds (the "pthaladyns") with 4-chloro-2-(2-(4-(hydroxymethyl)phenyl)-1,3-dioxoisoindoline-5-carboxamido)benzoic acid (29), a 4.58 +/- 0.06 microM dynamin I GTPase inhibitor. Pthaladyn-29 displays borderline selectivity for dynamin I relative to dynamin II ( approximately 5-10 fold). Only pthaladyn-23 (dynamin I IC(50) 17.4 +/- 5.8 microM) was an effective inhibitor of dynamin I mediated synaptic vesicle endocytosis in brain synaptosomes with an IC(50) of 12.9 +/- 5.9 microM. This compound was also competitive with respect to Mg(2+).GTP. Thus the pthaladyns are the first GTP competitive inhibitors of dynamin I and II GTPase and may be effective new tools for the study of neuronal endocytosis.
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Affiliation(s)
- Luke R Odell
- Chemistry, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia
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Bioanalytical tools for single-cell study of exocytosis. Anal Bioanal Chem 2010; 397:3281-304. [PMID: 20521141 DOI: 10.1007/s00216-010-3843-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 05/08/2010] [Accepted: 05/11/2010] [Indexed: 10/19/2022]
Abstract
Regulated exocytosis is a fundamental biological process used to deliver chemical messengers for cell-cell communication via membrane fusion and content secretion. A plethora of cell types employ this chemical-based communication to achieve crucial functions in many biological systems. Neurons in the brain and platelets in the circulatory system are representative examples utilizing exocytosis for neurotransmission and blood clotting. Single-cell studies of regulated exocytosis in the past several decades have greatly expanded our knowledge of this critical process, from vesicle/granule transport and docking at the early stages of exocytosis to membrane fusion and to eventual chemical messenger secretion. Herein, four main approaches that have been widely used to study single-cell exocytosis will be highlighted, including total internal reflection fluorescence microscopy, capillary electrophoresis, single-cell mass spectrometry, and microelectrochemistry. These techniques are arranged in the order following the route of a vesicle/granule destined for secretion. Within each section, the basic principles and experimental strategies are reviewed and representative examples are given revealing critical spatial, temporal, and chemical information of a secretory vesicle/granule at different stages of its lifetime. Lastly, an analytical chemist's perspective on potential future developments in this exciting field is discussed.
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18
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Glutamate. Its applications in food and contribution to health. Appetite 2010; 55:1-10. [PMID: 20470841 DOI: 10.1016/j.appet.2010.05.002] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 03/28/2010] [Accepted: 05/03/2010] [Indexed: 12/13/2022]
Abstract
This article reviews application of glutamate in food and its benefits and role as one of the common food ingredients used. Monosodium glutamate is one of the most abundant naturally occurring amino acids which frequently added as a flavor enhancer. It produced a unique taste that cannot be provided by other basic taste (saltiness, sourness, sweetness and bitterness), referred to as a fifth taste (umami). Glutamate serves some functions in the body as well, serving as an energy source for certain tissues and as a substrate for glutathione synthesis. Glutamate has the potential to enhance food intake in older individuals and dietary free glutamate evoked a visceral sensation from the stomach, intestine and portal vein. Small quantities of glutamate used in combination with a reduced amount of table salt during food preparation allow for far less salt to be used during and after cooking. Because glutamate is one of the most intensely studied food ingredients in the food supply and has been found safe, the Joint Expert Committee on Food Additives of the United Nations Food and Agriculture Organization and World Health Organization placed it in the safest category for food additives. Despite a widespread belief that glutamate can elicit asthma, migraine headache and Chinese Restaurant Syndrome (CRS), there are no consistent clinical data to support this claim. In addition, findings from the literature indicate that there is no consistent evidence to suggest that individuals may be uniquely sensitive to glutamate.
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Abstract
Central nerve terminals release neurotransmitter in response to a wide variety of stimuli. Because maintenance of neurotransmitter release is dependent on the continual supply of synaptic vesicles (SVs), nerve terminals possess an array of endocytosis modes to retrieve and recycle SV membrane and proteins. During mild stimulation conditions, single SV retrieval modes such as clathrin-mediated endocytosis predominate. However, during increased neuronal activity, additional SV retrieval capacity is required, which is provided by activity-dependent bulk endocytosis (ADBE). ADBE is the dominant SV retrieval mechanism during elevated neuronal activity. It is a high capacity SV retrieval mode that is immediately triggered during such stimulation conditions. This review will summarize the current knowledge regarding the molecular mechanism of ADBE, including molecules required for its triggering and subsequent steps, including SV budding from bulk endosomes. The molecular relationship between ADBE and the SV reserve pool will also be discussed. It is becoming clear that an understanding of the molecular physiology of ADBE will be of critical importance in attempts to modulate both normal and abnormal synaptic function during intense neuronal activity.
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Affiliation(s)
- Emma L. Clayton
- Membrane Biology Group, Centre for Integrative Physiology, George Square, University of Edinburgh, EH8 9XD, Scotland, U.K
| | - Michael A. Cousin
- Membrane Biology Group, Centre for Integrative Physiology, George Square, University of Edinburgh, EH8 9XD, Scotland, U.K
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20
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Clayton EL, Cousin MA. Quantitative monitoring of activity-dependent bulk endocytosis of synaptic vesicle membrane by fluorescent dextran imaging. J Neurosci Methods 2009; 185:76-81. [PMID: 19766140 DOI: 10.1016/j.jneumeth.2009.09.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Revised: 09/08/2009] [Accepted: 09/09/2009] [Indexed: 11/20/2022]
Abstract
Activity-dependent bulk endocytosis (ADBE) is the dominant synaptic vesicle (SV) retrieval mode in central nerve terminals during periods of intense neuronal activity. Despite this fact there are very few real time assays that report the activity of this critical SV retrieval mode. In this paper we report a simple and quantitative assay of ADBE using uptake of large flourescent dextrans as fluid phase markers. We show that almost all dextran uptake occurs in nerve terminals, using co-localisation with the fluorescent probe FM1-43. We also demonstrate that accumulated dextran cannot be unloaded by neuronal stimulation, indicating its specific loading into bulk endosomes and not SVs. Quantification of dextran uptake was achieved by using thresholding analysis to count the number of loaded nerve terminals, since monitoring the average fluorescence intensity of these nerve terminals did not accurately report the extent of ADBE. Using this analysis we showed that dextran uptake occurs very soon after stimulation and that it does not persist when stimulation terminates. Thus we have devised a simple and quantitative method to monitor ADBE in living neurones, which will be ideal for real time screening of small molecule inhibitors of this key SV retrieval mode.
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Affiliation(s)
- Emma Louise Clayton
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, Scotland, UK
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21
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Giardino L, Armelloni S, Corbelli A, Mattinzoli D, Zennaro C, Guerrot D, Tourrel F, Ikehata M, Li M, Berra S, Carraro M, Messa P, Rastaldi MP. Podocyte glutamatergic signaling contributes to the function of the glomerular filtration barrier. J Am Soc Nephrol 2009; 20:1929-40. [PMID: 19578006 DOI: 10.1681/asn.2008121286] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Podocytes possess the complete machinery for glutamatergic signaling, raising the possibility that neuron-like signaling contributes to glomerular function. To test this, we studied mice and cells lacking Rab3A, a small GTPase that regulates glutamate exocytosis. In addition, we blocked the glutamate ionotropic N-methyl-d-aspartate receptor (NMDAR) with specific antagonists. In mice, the absence of Rab3A and blockade of NMDAR both associated with an increased urinary albumin/creatinine ratio. In humans, NMDAR blockade, obtained by addition of ketamine to general anesthesia, also had an albuminuric effect. In vitro, Rab3A-null podocytes displayed a dysregulated release of glutamate with higher rates of spontaneous exocytosis, explained by a reduction in Rab3A effectors resulting in freedom of vesicles from the actin cytoskeleton. In addition, NMDAR antagonism led to profound cytoskeletal remodeling and redistribution of nephrin in cultured podocytes; the addition of the agonist NMDA reversed these changes. In summary, these results suggest that glutamatergic signaling driven by podocytes contributes to the integrity of the glomerular filtration barrier and that derangements in this signaling may lead to proteinuric renal diseases.
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Affiliation(s)
- Laura Giardino
- Renal Research Laboratory, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena and Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milan, Italy
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22
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Hill TA, Gordon CP, McGeachie AB, Venn-Brown B, Odell LR, Chau N, Quan A, Mariana A, Sakoff JA, Chircop (nee Fabbro) M, Robinson PJ, McCluskey A. Inhibition of Dynamin Mediated Endocytosis by the Dynoles—Synthesis and Functional Activity of a Family of Indoles. J Med Chem 2009; 52:3762-73. [DOI: 10.1021/jm900036m] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Timothy A. Hill
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
| | - Christopher P. Gordon
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
| | - Andrew B. McGeachie
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
| | - Barbara Venn-Brown
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
| | - Luke R. Odell
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
| | - Ngoc Chau
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
| | - Annie Quan
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
| | - Anna Mariana
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
| | - Jennette A. Sakoff
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
| | - Megan Chircop (nee Fabbro)
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
| | - Phillip J. Robinson
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
| | - Adam McCluskey
- Chemistry, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia, Cell Signaling Unit, Children’s Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead NSW 2145, Australia, Department of Medical Oncology, Calvary Mater Newcastle, Edith Street, Waratah NSW 2298, Australia
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23
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Darya K, Ganguly A, Lee D. Quantitative analysis of synaptic boutons in Drosophila primary neuronal cultures. Brain Res 2009; 1280:1-12. [PMID: 19460362 DOI: 10.1016/j.brainres.2009.05.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 05/11/2009] [Accepted: 05/12/2009] [Indexed: 11/25/2022]
Abstract
Little information is currently available for structural and quantitative aspects of Drosophila central synapses due to difficulties in accessing those synapses in the tiny fly brain. Here, we developed a new approach to quantitatively analyze central synapses using Drosophila primary neuronal cultures. Two different markers were used to identify synaptic boutons: GFP marking with a synaptotagmin (Syt)::eGFP transgene and anti-Syt antibody. These markers clearly recognized puncta-like synaptic boutons and both signals were well overlapped. In addition, these puncta signals were completely absent in neuronal cultures derived from a Syt null mutant Syt(AD4), firmly demonstrating that anti-Syt(+) puncta are presynaptic terminals. Since anti-Syt signals were stronger and extensive, it was chosen to quantify synaptic boutons in the neuronal culture. Using an image analysis software Image J, synaptic boutons were quantified on the basis of the size and intensity of anti-Syt(+) signals. The number of synaptic boutons in wild type neurons increased by 27% between 3 and 9 days in culture. This increase was much greater (142%) in neuronal cultures derived from a FasII(e86) mutant known to show alterations in synapse growth and stabilization. A parallel increase in neurite length was also observed in both wild type and FasII(e86) neurons. Interestingly, the number of GABAergic synaptic boutons did not increase during this time, indicating distinctive mechanisms underlying development and maintenance of specific types of boutons. Our results successfully showed that Drosophila synaptic boutons can be quantified and thus we can examine genes and signaling pathways regulating structural properties of central synapses in Drosophila.
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Affiliation(s)
- Kauroon Darya
- Department of Biological Sciences, Ohio University, Athens, OH 45701, USA
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24
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Görg B, Morwinsky A, Keitel V, Qvartskhava N, Schrör K, Häussinger D. Ammonia triggers exocytotic release of L-glutamate from cultured rat astrocytes. Glia 2009; 58:691-705. [DOI: 10.1002/glia.20955] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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25
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Otomo M, Takahashi K, Miyoshi H, Osada K, Nakashima H, Yamaguchi N. Some selective serotonin reuptake inhibitors inhibit dynamin I guanosine triphosphatase (GTPase). Biol Pharm Bull 2008; 31:1489-95. [PMID: 18670077 DOI: 10.1248/bpb.31.1489] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neuronal dynamin I plays a critical role in the recycling of synaptic vesicles, and thus in nervous system function. We expressed and purified dynamin I to explore potentially clinically useful endocytosis inhibitors and to examine the mechanism of their action. We estimated the IC(50) of nineteen psychotropic drugs for dynamin I. The IC(50) values of two selective serotonin reuptake inhibitors (sertraline and fluvoxamine) were 7.3+/-1.0 and 14.7+/-1.6 microM, respectively. Kinetic analyses revealed that fluvoxamine is a noncompetitive inhibitor of dynamin I guanosine triphosphatase (GTPase) with respect to guanosine 5'-triphosphate (GTP) and a competitive inhibitor with respect to L-phosphatidylserine (PS). Fluvoxamine may compete with PS for binding to the pleckstrin homology domain of dynamin I. On the other hand, sertraline was a mixed type inhibitor with respect to both GTP and PS. Our results indicate that sertraline and fluvoxamine may regulate the transportation of neurotransmitters by modulating synaptic vesicle endocytosis via the inhibition of dynamin I GTPase.
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Affiliation(s)
- Masahiro Otomo
- Department of Neuropsychiatry, St. Marianna University School of Medicine, Kanagawa, Japan
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26
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Cousin MA. Use of FM1-43 and other derivatives to investigate neuronal function. ACTA ACUST UNITED AC 2008; Chapter 2:Unit 2.6. [PMID: 18428675 DOI: 10.1002/0471142301.ns0206s43] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The fluorescent dye FM1-43 and its derivatives can be used to monitor the physiology of synaptic vesicle turnover in central nerve terminals. They do so by their ability to reversibly partition into membranes, a process that results in a huge increase in fluorescence in comparison to their quantum yield in solution. This unit provides protocols for quantifying total synaptic vesicle turnover, the kinetics and extent of synaptic vesicle exocytosis, and the kinetics and mode of synaptic vesicle endocytosis. Descriptions of other ways these protocols have been used to derive information about the life cycle of the synaptic vesicle are also provided.
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27
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Leenders M, Gerwin C, Sheng ZH. Multidisciplinary approaches for characterizing synaptic vesicle proteins. ACTA ACUST UNITED AC 2008; Chapter 2:Unit 2.7. [PMID: 18428598 DOI: 10.1002/0471142301.ns0207s28] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Investigation of synaptic vesicle membrane proteins using multidisciplinary approaches, particularly to characterize synaptic vesicle proteins in synapses, can greatly advance our knowledge of the molecular mechanisms involved in synaptic vesicle exocytosis and neurotransmission. Three approaches are presented in this unit to identify and characterize synaptic vesicle proteins. The first is a subcellular fractionation method used to isolate synaptic vesicles from rat brain synaptosomal preparations, which can then be used in a variety of biochemical studies on synaptic vesicle proteins. The second is a detailed procedure for pre-embedding immunogold staining and electron microscopic observation, techniques that permit the morphological identification of synaptic vesicle proteins in individual vesicles at the intact synapse. Finally, a protocol for immunocytochemical staining of cultured hippocampal neurons for light microscopic examination is provided, which allows one to stain multisynaptic vesicle proteins and determine their localization in relation to other proteins or subcellular structures in synapses.
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Affiliation(s)
- Miriam Leenders
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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28
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Anggono V, Cousin MA, Robinson PJ. Styryl dye-based synaptic vesicle recycling assay in cultured cerebellar granule neurons. Methods Mol Biol 2008; 457:333-345. [PMID: 19066039 DOI: 10.1007/978-1-59745-261-8_25] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Neurons transmit information by exocytosis of synaptic vesicles (SV), which contain neurotransmitter. Exocytosis is followed by efficient retrieval of the plasma membrane by endocytosis to generate a new SV. SV retrieval supports multiple cycles of synaptic transmission. Over the years, styryl dyes have been widely used to probe the mechanism of SV recycling in the processes of cultured neurons. The styryl dye method is complementary to electrophysiological measurements or genetic reporter approaches. Owing to their ease to culture, cerebellar granule neurons provide a robust neuronal model system for the assay. These cells are readily transfected with various DNA constructs to study the function of exocytic or endocytic proteins in SV recycling.
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Affiliation(s)
- Victor Anggono
- Children's Medical Research Institute, Wentworthville, New South Wales, Australia
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29
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Kreda SM, Okada SF, van Heusden CA, O'Neal W, Gabriel S, Abdullah L, Davis CW, Boucher RC, Lazarowski ER. Coordinated release of nucleotides and mucin from human airway epithelial Calu-3 cells. J Physiol 2007; 584:245-59. [PMID: 17656429 PMCID: PMC2277076 DOI: 10.1113/jphysiol.2007.139840] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The efficiency of the mucociliary clearance (MCC) process that removes noxious materials from airway surfaces depends on the balance between mucin secretion, airway surface liquid (ASL) volume, and ciliary beating. Effective mucin dispersion into ASL requires salt and water secretion onto the mucosal surface, but how mucin secretion rate is coordinated with ion and, ultimately, water transport rates is poorly understood. Several components of MCC, including electrolyte and water transport, are regulated by nucleotides in the ASL interacting with purinergic receptors. Using polarized monolayers of airway epithelial Calu-3 cells, we investigated whether mucin secretion was accompanied by nucleotide release. Electron microscopic analyses of Calu-3 cells identified subapical granules that resembled goblet cell mucin granules. Real-time confocal microscopic analyses revealed that subapical granules, labelled with FM 1-43 or quinacrine, were competent for Ca(2+)-regulated exocytosis. Granules containing MUC5AC were apically secreted via Ca(2+)-regulated exocytosis as demonstrated by combined immunolocalization and slot blot analyses. In addition, Calu-3 cells exhibited Ca(2+)-regulated apical release of ATP and UDP-glucose, a substrate of glycosylation reactions within the secretory pathway. Neither mucin secretion nor ATP release from Calu-3 cells were affected by activation or inhibition of the cystic fibrosis transmembrane conductance regulator. In SPOC1 cells, an airway goblet cell model, purinergic P2Y(2) receptor-stimulated increase of cytosolic Ca(2+) concentration resulted in secretion of both mucins and nucleotides. Our data suggest that nucleotide release is a mechanism by which mucin-secreting goblet cells produce paracrine signals for mucin hydration within the ASL.
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Affiliation(s)
- Silvia M Kreda
- Cystic Fibrosis/Pulmonary Research and Treatment Center, The University of North Carolina at Chapel Hill, 7017 Thurston Bowles Building, Chapel Hill, NC 27599-7248, USA.
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30
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Thompson SEM, Callow JA, Callow ME, Wheeler GL, Taylor AR, Brownlee C. Membrane recycling and calcium dynamics during settlement and adhesion of zoospores of the green alga Ulva linza. PLANT, CELL & ENVIRONMENT 2007; 30:733-44. [PMID: 17470149 DOI: 10.1111/j.1365-3040.2007.01661.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Recruitment of individuals of the marine alga Ulva linza on to a suitable habitat involves the settlement of motile zoospores on to a substratum during which a preformed adhesive is secreted by vesicular exocytosis. The fluorescent styryl dye FM 1-43 and fluorescent Ca(2+) indicators were used to follow membrane cycling and changes in cytosolic Ca(2+) ([Ca(2+)](cyt)) associated with settlement. When swimming zoospores were exposed continuously to FM 1-43, the plasma membrane was preferentially labelled. During settlement, FM 1-43-labelled plasma membrane was rapidly internalized reflecting high membrane turnover. The internalized membrane was focused into a discrete region indicating targeting of membrane to an endosome-like compartment. Acetoxymethyl (AM)-ester derivatives were found to be unsuitable for monitoring [Ca(2+)](cyt) because the dyes were rapidly sequestered from the cytoplasm into sub-cellular compartments. [Ca(2+)](cyt) was, however, reliably measured using dextran-conjugated calcium indicators delivered into cells using a biolistic technique. Cells loaded with Oregon Green BAPTA-1 dextran (Invitrogen, Paisley, UK) showed diffuse cytosolic loading and reliably responded to imposed changes in [Ca(2+)](cyt). During settlement, zoospores exhibited both localized and diffuse increases in [Ca(2+)](cyt) implying a role for [Ca(2+)](cyt) in exocytosis of the adhesive.
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Affiliation(s)
- S E M Thompson
- School of Biosciences, The University of Birmingham, Birmingham, and Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, UK
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31
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Abstract
FM dyes have been used to label and then monitor synaptic vesicles, secretory granules and other endocytic structures in a variety of preparations. Here, we describe the general procedure for using FM dyes to study endosomal trafficking in general, and synaptic vesicle recycling in particular. The dye, dissolved in normal saline solution, is added to a chamber containing the preparation to be labeled. Stimulation evokes exocytosis, and compensatory endocytosis that follows traps FM dye inside the retrieved vesicles. The extracellular dye is then washed from the chamber, and labeled endocytic structures are examined with a fluorescence microscope. Fluorescence intensity provides a direct measure of the labeled vesicle number, a good measure of the amount of exocytosis. If the preparation is stimulated again, without dye in the chamber, dimming of the preparation provides a measure of exocytosis of labeled vesicles. With a synaptic preparation on hand, this protocol requires 1 day.
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Affiliation(s)
- Michael A Gaffield
- Neuroscience Program, University of Colorado Medical School, Aurora, Colorado 80045, USA
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32
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Evans GJO, Cousin MA. Simultaneous monitoring of three key neuronal functions in primary neuronal cultures. J Neurosci Methods 2006; 160:197-205. [PMID: 17049620 PMCID: PMC2225589 DOI: 10.1016/j.jneumeth.2006.09.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Revised: 08/25/2006] [Accepted: 09/02/2006] [Indexed: 11/22/2022]
Abstract
The coupling of Ca2+ influx to synaptic vesicle (SV) recycling in nerve terminals is essential for neurotransmitter release and thus neuronal communication. Both of these parameters have been monitored using fluorescent reporter dyes such as fura-2 and FM1-43 in single central nerve terminals. However, their simultaneous monitoring has been hampered by the proximity of their fluorescence spectra, resulting in significant contamination of their signals by bleedthrough. We have developed an assay that simultaneously monitors both SV recycling and changes in intracellular free Ca2+ ([Ca2+]i) in cultured neurons using the reporter dyes FM4-64 and fura-2AM. By monitoring both fura-2 and FM4-64 emission in the far red range, we were able to visualize functionally independent readouts of both SV recycling and [Ca2+]i independent of fluorescence bleedthrough. We were also able to incorporate an assay of cell viability without any fluorescence bleedthrough from either fura-2 or FM4-64 signals, using the dye SYTOX Green. We propose that this assay of three key neuronal functions could be simply translated into a high content screening format for studies investigating small molecule inhibitors of these processes.
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33
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Zefirov AL, Abdrakhmanov MM, Mukhamedyarov MA, Grigoryev PN. The role of extracellular calcium in exo- and endocytosis of synaptic vesicles at the frog motor nerve terminals. Neuroscience 2006; 143:905-10. [PMID: 17000054 DOI: 10.1016/j.neuroscience.2006.08.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 08/16/2006] [Accepted: 08/16/2006] [Indexed: 11/26/2022]
Abstract
In the present study we combined FM 1-43 imaging and electrophysiological recording of miniature end-plate currents (MEPCs) to determine the role of extracellular calcium in synaptic vesicle exo- and endocytosis at the frog motor nerve terminals. We replaced extracellular Ca2+ ions with other bivalent cations (Sr2+, Ba2+, Cd2+, Mg2+) or used a calcium-free solution and monitored fluorescent staining of the nerve terminals in the presence of caffeine, which promotes the release of Ca2+ from intracellular stores. Caffeine has induced FM1-43 internalization only in the presence of bivalent cations in the external solution. The exposure of the neuromuscular junction to caffeine in a calcium-free solution caused a reversible failure of FM 1-43 loading and an increase in the nerve terminal width. This effect of a calcium-free solution was not due to a decrease in exocytosis, because caffeine-induced FM1-43 unloading from the previously loaded nerve terminals, as well as a degree of the MEPCs frequency increase, was unchanged. We conclude that the presence of Ca2+ or other bivalent cations in extracellular space is necessary for endocytosis but not for exocytosis of synaptic vesicles, while transmitter release is promoted by efflux of Ca2+ from intracellular stores. The effect of extracellular Ca2+ on endocytosis might be driven by the non-specific interactions with membrane lipids.
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Affiliation(s)
- A L Zefirov
- Department of Physiology, Kazan State Medical University, Butlerov Street 49, Kazan, Russia 420012
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34
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Kirvell SL, Esiri M, Francis PT. Down-regulation of vesicular glutamate transporters precedes cell loss and pathology in Alzheimer's disease. J Neurochem 2006; 98:939-50. [PMID: 16893425 DOI: 10.1111/j.1471-4159.2006.03935.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Alzheimer's disease (AD) is characterized pathologically by plaques, tangles, and cell and synapse loss. As glutamate is the principle excitatory neurotransmitter of the CNS, the glutamatergic system may play an important role in AD. An essential step in glutamate neurotransmission is the concentration of glutamate into synaptic vesicles before release from the presynaptic terminal. Recently a group of proteins responsible for uptake has been identified - the vesicular glutamate transporters (VGLUTs). The generation of antibodies has facilitated the study of glutamatergic neurones. Here, we used antibodies to the VGLUTs together with immunohistochemistry and western blotting to investigate the status of glutamatergic neurones in temporal, parietal and occipital cortices of patients with AD; these regions were chosen to represent severely, moderately and mildly affected regions at the end stage of the disease. There was no change in expression of the synaptic markers in relation to total protein in the temporal cortex, but a significant reduction in synaptophysin and VGLUT1 was found in both the parietal and occipital cortices. These changes were found to relate to the number of tangles in the temporal cortex. There were no correlations with either mental test score or behaviour syndromes, with the exception of depression.
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Affiliation(s)
- Sara L Kirvell
- Wolfson Centre for Age-Related Diseases, Kings College London, London, UK
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35
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Waseem TV, Kolos VA, Lapatsina LP, Fedorovich SV. Influence of cholesterol depletion in plasma membrane of rat brain synaptosomes on calcium-dependent and calcium-independent exocytosis. Neurosci Lett 2006; 405:106-10. [PMID: 16835010 DOI: 10.1016/j.neulet.2006.06.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Revised: 06/08/2006] [Accepted: 06/14/2006] [Indexed: 11/16/2022]
Abstract
It is well established that calcium-dependent neurotransmitter release and exocytosis can be regulated by altering the cholesterol content of the plasma membrane. We have compared the influence of cholesterol depletion of synaptosomal plasma membrane by 15 mM methyl-beta-cyclodextrin (MCD) treatment on calcium-dependent release of D-[(3)H]aspartate induced by the calcium ionophore A23187 and on calcium-independent release induced by hypertonic shrinking or polyvalent cations. We found that decrease of cholesterol concentration by 9.3% inhibited calcium-dependent release of d-[(3)H]aspartate induced by calcium ionophore A23187 by four times while release induced by 300 microM Gd(3+), 150 mM and 500 mM sucrose remained unchanged. Further we have investigated the influence of MCD on exocytosis monitored by the fluorescent dye, acridine orange. Cholesterol depletion inhibited calcium-dependent exocytosis induced by calcium ionophore A23187 but had virtually no influence on calcium-independent exocytosis induced by hypertonic shrinking or Gd(3+). In summary, we found that the cholesterol content in synaptosomal plasma membrane is important for calcium-dependent exocytosis.
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Affiliation(s)
- Tatyana V Waseem
- Institute of Biophysics and Cell Engineering, Akademicheskaya St., 27, Minsk 220072, Belarus
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36
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Rastaldi MP, Armelloni S, Berra S, Calvaresi N, Corbelli A, Giardino LA, Li M, Wang GQ, Fornasieri A, Villa A, Heikkila E, Soliymani R, Boucherot A, Cohen CD, Kretzler M, Nitsche A, Ripamonti M, Malgaroli A, Pesaresi M, Forloni GL, Schlöndorff D, Holthofer H, D'Amico G. Glomerular podocytes contain neuron-like functional synaptic vesicles. FASEB J 2006; 20:976-8. [PMID: 16585060 DOI: 10.1096/fj.05-4962fje] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Although patients with chronic renal failure are increasing worldwide, many aspects of kidney biology remain to be elucidated. Recent research has uncovered several molecular properties of the glomerular filtration barrier, in which podocytes, highly differentiated, ramified cells that enwrap the glomerular basement membrane, have been reported to be mainly responsible for filter's selectivity. We previously described that podocytes express Rab3A, a GTPase restricted to cell types that are capable of highly regulated exocytosis, such as neuronal cells. Here, we first demonstrate by a proteomic study that Rab3A in podocytes coimmmunoprecipitates with molecules once thought to be synapse specific. We then show that podocytes possess structures resembling synaptic vesicles, which contain glutamate, coexpress Rab3A and synaptotagmin 1, and undergo spontaneous and stimulated exocytosis and recycling, with glutamate release. Finally, from the results of a cDNA microarray study, we describe the presence of a series of neuron- and synapse-specific molecules in normal human glomeruli and confirm the glomerular protein expression of both metabotropic and ionotropic glutamate receptors. These data point toward a synaptic-like mechanism of communication among glomerular cells, which perfectly fits with the molecular composition of the glomerular filter and puts in perspective several previous observations, proposing a different working hypothesis for understanding glomerular signaling dynamics.
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Affiliation(s)
- Maria Pia Rastaldi
- Renal Immunopathology Laboratory, Associazione Nuova Nefrologia and Fondazione D'Amico per la Ricerca sulle Malattie Renali, c/o San Carlo Borromeo Hospital, via Pio II, 3, Milan 20153, Italy.
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37
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Evans GJO, Cousin MA. Tyrosine phosphorylation of synaptophysin in synaptic vesicle recycling. Biochem Soc Trans 2006; 33:1350-3. [PMID: 16246116 PMCID: PMC2077014 DOI: 10.1042/bst20051350] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The integral SV (synaptic vesicle) protein synaptophysin was one of the first nerve terminal proteins identified. However its role, if any, in the SV life cycle remains undetermined. One of the most prominent features of synaptophysin is that its cytoplasmic C-terminus largely consists of pentapeptide repeats initiated by a tyrosine residue. Synaptophysin is heavily phosphorylated by tyrosine kinases in the nerve terminal, suggesting that this phosphorylation is central to its function. This review will cover the evidence for tyrosine phosphorylation of synaptophysin and how this phosphorylation may control its function in the SV life cycle.
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Affiliation(s)
- G J O Evans
- Membrane Biology Group, Centre for Integrative Physiology, George Square, University of Edinburgh, Edinburgh EH8 9XD, UK
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38
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Pamidimukkala J, Habibi S, Hay M. Frequency-dependent depression of exocytosis and the role of voltage-gated calcium channels. Brain Res 2006; 1078:1-8. [PMID: 16492381 DOI: 10.1016/j.brainres.2006.01.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Revised: 01/09/2006] [Accepted: 01/16/2006] [Indexed: 10/25/2022]
Abstract
Synaptic vesicle exocytosis in primary cultures of baroreceptor neurons is reduced during high-frequency stimulation. Calcium influx through voltage-gated calcium channels (VGCC) is a key step in neurotransmitter release. With the help of FM2-10, a marker of synaptic vesicle recycling, the present study investigates the differential contribution of several VGCC subtypes to exocytosis in neuronal processes and how this contribution is altered at high frequencies. In control experiments, field stimulation at 0.5 Hz evoked about 66 +/- 5% destaining. Combined blockade of N- and P/Q-subtypes with Ctx-MVIIC was far more effective in reducing exocytosis (11 +/- 8%) than blocking N-type (49 +/- 5%, Ctx-GVIA) or P-type (46 +/- 1%, Agatoxin) alone. The effectiveness of the blockers also varied with the duration of stimulation: Ctx-GVIA attenuating exocytosis significantly in the first 60 s and Agatoxin affecting exocytosis only towards the end of 180 s stimulation period. Field stimulation at 10 Hz evoked exocytosis (36 +/- 18%) comparable to that evoked by 0.5 Hz in the presence of Ctx-GVIA. While blockade with Agatoxin had no effects, Ctx-GVIA, Ctx-MVIIC and L-type blocker Nifedepine had small but similar inhibitory effects on exocytosis at 10 Hz. The data suggest that N-type is the major contributor to exocytosis at 0.5 Hz, and this contribution is reduced during prolonged stimulation periods and at high frequencies.
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Affiliation(s)
- Jaya Pamidimukkala
- Dalton Cardiovascular Research Center, 134 Research Park, University of Missouri, Columbia, MO 65211, USA.
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39
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Fedorovich SV, Waseem TV, Lavrukevich TV, Konev SV. Role of Calcium in Exocytosis Induced by Hypotonic Swelling. Ann N Y Acad Sci 2006; 1048:337-40. [PMID: 16154946 DOI: 10.1196/annals.1342.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We studied the influence of Ca(2+) on exocytosis induced by hypotonic shock using the fluorescent dyes acridine orange FM1-43 and FM2-10. It was shown using acridine orange that lowering osmolarity to 230 mOsm/L induces exocytosis both in calcium-containing and calcium-free media. By contrast, we were able to demonstrate calcium dependence of exocytosis using styryl dyes. Lowering osmolarity leads to an increase of neurotransmitter release in a calcium-independent manner. Thus, our data suggest that hypotonic swelling induces calcium-independent exocytosis. Calcium influx mediated by stretch channels is able to switch mode of exocytosis from "kiss and run" to full fusion.
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40
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Morgenthaler FD, Kraftsik R, Catsicas S, Magistretti PJ, Chatton JY. Glucose and lactate are equally effective in energizing activity-dependent synaptic vesicle turnover in purified cortical neurons. Neuroscience 2006; 141:157-65. [PMID: 16713114 DOI: 10.1016/j.neuroscience.2006.03.065] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2005] [Revised: 03/22/2006] [Accepted: 03/23/2006] [Indexed: 11/19/2022]
Abstract
This study examines the role of glucose and lactate as energy substrates to sustain synaptic vesicle cycling. Synaptic vesicle turnover was assessed in a quantitative manner by fluorescence microscopy in primary cultures of mouse cortical neurons. An electrode-equipped perfusion chamber was used to stimulate cells both by electrical field and potassium depolarization during image acquisition. An image analysis procedure was elaborated to select in an unbiased manner synaptic boutons loaded with the fluorescent dye N-(3-triethylammoniumpropyl)-4-(4-(dibutylamino)styryl)pyridinium dibromide (FM1-43). Whereas a minority of the sites fully released their dye content following electrical stimulation, others needed subsequent K(+) depolarization to achieve full release. This functional heterogeneity was not significantly altered by the nature of metabolic substrates. Repetitive stimulation sequences of FM1-43 uptake and release were then performed in the absence of any metabolic substrate and showed that the number of active sites dramatically decreased after the first cycle of loading/unloading. The presence of 1 mM glucose or lactate was sufficient to sustain synaptic vesicle cycling under these conditions. Moreover, both substrates were equivalent for recovery of function after a phase of decreased metabolic substrate availability. Thus, lactate appears to be equivalent to glucose for sustaining synaptic vesicle turnover in cultured cortical neurons during activity.
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Affiliation(s)
- F D Morgenthaler
- Department of Physiology, University of Lausanne, Lausanne, Switzerland
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41
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Abstract
The integral SV (synaptic vesicle) protein synaptophysin was one of the first nerve terminal proteins identified. However its role, if any, in the SV life cycle remains undetermined. One of the most prominent features of synaptophysin is that its cytoplasmic C-terminus largely consists of pentapeptide repeats initiated by a tyrosine residue. Synaptophysin is heavily phosphorylated by tyrosine kinases in the nerve terminal, suggesting that this phosphorylation is central to its function. This review will cover the evidence for tyrosine phosphorylation of synaptophysin and how this phosphorylation may control its function in the SV life cycle.
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42
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Waseem TV, Rakovich AA, Lavrukevich TV, Konev SV, Fedorovich SV. Calcium regulates the mode of exocytosis induced by hypotonic shock in isolated neuronal presynaptic endings. Neurochem Int 2005; 46:235-42. [PMID: 15670640 DOI: 10.1016/j.neuint.2004.09.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Accepted: 09/20/2004] [Indexed: 11/19/2022]
Abstract
A decrease in the osmolarity of incubation medium is accompanied by calcium influx in neuronal presynaptic endings. We studied the influence of Ca2+ on exocytosis induced by hypotonic shock using the hydrophilic fluorescent dye acridine orange and the hydrophobic fluorescent dye FM2-10. It was shown using acridine orange that lowering of osmolarity to 230 mOsm/l induces exocytosis both in calcium-containing and calcium-free medium. By contrast, we were able to demonstrate calcium-dependence of exocytosis using styryl dye FM2-10. Lowering of osmolarity leads to increase of [3H]D-aspartate and [3H]GABA release in calcium-free medium. Addition of calcium inhibits hypotonic-induced neurotransmitter release. Decreasing of NaCl concentration to 92 mM in isotonic medium is able to induce d-aspartate and GABA release. Thus, our data suggest that hypotonic swelling induces calcium-independent exocytosis possibly by a "kiss and run" mechanism. Calcium influx mediated by stretch channels is able to provoke full fusion between plasma membrane and synaptic vesicles. [3H]D-aspartate and [3H]GABA released by hypotonic shock is determined by sodium lowering rather than by osmolarity decreasing itself.
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Affiliation(s)
- Tatyana V Waseem
- Institute of Biophysics and Cell Engineering, Akademicheskaya St., 27, Minsk 220072, Belarus
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43
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Kumashiro S, Lu YF, Tomizawa K, Matsushita M, Wei FY, Matsui H. Regulation of synaptic vesicle recycling by calcineurin in different vesicle pools. Neurosci Res 2005; 51:435-43. [PMID: 15740806 DOI: 10.1016/j.neures.2004.12.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Revised: 12/21/2004] [Accepted: 12/21/2004] [Indexed: 11/19/2022]
Abstract
The synaptic vesicles keep recycling by the processes of endocytosis and exocytosis to maintain the normal synaptic transmission. The synaptic vesicles are classified as the readily releasable pool (RRP) and the reserve pool (RP). In the endocytosis process, calcineurin (CaN), a Ca2+/calmodulin-dependent protein phosphatase, has been shown to play important roles. However, it is unclear about its roles in different vesicle pools. Here, we investigated the role of CaN in the regulation of vesicle recycling in the RRP and RP. Vesicle recycling was monitored by using fluorescent dyes FM1-43 and FM4-64 in the primary cultures of hippocampal neurons. Inhibition of CaN by FK506 and cyclosporin A suppressed the endocytosis in the RP, but not in the RRP. Inhibition of CaN also restrained the exocytic process triggered by 10 Hz stimulation, but had no effect on 3-5 Hz stimulation-induced exocytosis. FK506 also reduced the total vesicle pool size in the synaptic terminals. A synthesized CaN inhibitory peptide showed the similar effects as FK506 and cyclosporin A. These results revealed a novel mechanism that CaN plays critical roles in the distinct vesicle recycling processes.
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Affiliation(s)
- Susumu Kumashiro
- Department of Physiology, Okayama University Graduate School of Medicine and Dentistry, Okayama 700-8558, Japan
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44
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Hill TA, Odell LR, Quan A, Abagyan R, Ferguson G, Robinson PJ, McCluskey A. Long chain amines and long chain ammonium salts as novel inhibitors of dynamin GTPase activity. Bioorg Med Chem Lett 2005; 14:3275-8. [PMID: 15149689 DOI: 10.1016/j.bmcl.2004.03.096] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2003] [Accepted: 03/29/2004] [Indexed: 11/26/2022]
Abstract
We examined a number of ligands with the view of inhibiting the GTPase activity of dynamin. Dynamin contains a pleckstrin homology (PH) domain that interacts with lipids. We report a series of simple lipid-like molecules that display moderate inhibitory activity. Inhibitory activity is linked to chain length and quaternarization of the terminal amine. A change in the counterion, Cl versus Br or I, had little effect on potency. However, introduction of a hydrophobic collar proximal to the charged site was beneficial to dynamin GTPase inhibitory action. The most potent compound was myristoyl trimethyl ammonium bromide (MTMAB, IC(50) 3.15 microM).
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Affiliation(s)
- Timothy A Hill
- Advanced Synthetic Materials Group, Chemistry Building, School Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia
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45
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Duncan RR, Bergmann A, Cousin MA, Apps DK, Shipston MJ. Multi-dimensional time-correlated single photon counting (TCSPC) fluorescence lifetime imaging microscopy (FLIM) to detect FRET in cells. J Microsc 2004; 215:1-12. [PMID: 15230870 PMCID: PMC1903372 DOI: 10.1111/j.0022-2720.2004.01343.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present a novel, multi-dimensional, time-correlated single photon counting (TCSPC) technique to perform fluorescence lifetime imaging with a laser-scanning microscope operated at a pixel dwell-time in the microsecond range. The unsurpassed temporal accuracy of this approach combined with a high detection efficiency was applied to measure the fluorescent lifetimes of enhanced cyan fluorescent protein (ECFP) in isolation and in tandem with EYFP (enhanced yellow fluorescent protein). This technique enables multi-exponential decay analysis in a scanning microscope with high intrinsic time resolution, accuracy and counting efficiency, particularly at the low excitation levels required to maintain cell viability and avoid photobleaching. Using a construct encoding the two fluorescent proteins separated by a fixed-distance amino acid spacer, we were able to measure the fluorescence resonance energy transfer (FRET) efficiency determined by the interchromophore distance. These data revealed that ECFP exhibits complex exponential fluorescence decays under both FRET and non-FRET conditions, as previously reported. Two approaches to calculate the distance between donor and acceptor from the lifetime delivered values within a 10% error range. To confirm that this method can be used also to quantify intermolecular FRET, we labelled cultured neurones with the styryl dye FM1-43, quantified the fluorescence lifetime, then quenched its fluorescence using FM4-64, an efficient energy acceptor for FM1-43 emission. These experiments confirmed directly for the first time that FRET occurs between these two chromophores, characterized the lifetimes of these probes, determined the interchromophore distance in the plasma membrane and provided high-resolution two-dimensional images of lifetime distributions in living neurones.
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Affiliation(s)
- R R Duncan
- Membrane Biology Group, University of Edinburgh, George Square, EH8 9XD, UK.
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46
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Küppers-Munther B, Letzkus JJ, Lüer K, Technau G, Schmidt H, Prokop A. A new culturing strategy optimises Drosophila primary cell cultures for structural and functional analyses. Dev Biol 2004; 269:459-78. [PMID: 15110713 DOI: 10.1016/j.ydbio.2004.01.038] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Revised: 12/08/2003] [Accepted: 01/28/2004] [Indexed: 11/24/2022]
Abstract
Neurons in primary cell cultures provide important experimental possibilities complementing or substituting those in the nervous system. However, Drosophila primary cell cultures have unfortunate limitations: they lack either a range of naturally occurring cell types, or of mature physiological properties. Here, we demonstrate a strategy which supports both aspects integrated in one culture: Initial culturing in conventional serum-supplemented Schneider's medium (SM(20K)) guarantees acquisition of all properties known from 30 years of work on cell type-specific differentiation in this medium. Through subsequent shift to newly developed active Schneider's medium (SM(active)), neurons adopt additional mature properties like the ability to carry out plastic morphological changes, neurotransmitter expression and electrical activity. We introduce long-term FM-dye measurements as a tool for Drosophila primary cell cultures demonstrating the presence of increased, action potential-dependent synaptic activity in SM(active). This is confirmed by patch-clamp recordings, which in addition show that SM(active)-cultured neurons display different spiking patterns. Furthermore, we demonstrate that transmission can be evoked in SM(active) cultures, revealing the existence of synaptic plasticity. Thus, these culture conditions support developmental, structural and physiological properties known or expected from the nervous system, enhancing possibilities for future experiments complementing or substituting those in nervous systems of Drosophila.
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47
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Pamidimukkala J, Hay M. Frequency dependence of synaptic vesicle exocytosis in aortic baroreceptor neurons and the role of group III mGluRs. Brain Res 2004; 1006:215-24. [PMID: 15051525 DOI: 10.1016/j.brainres.2003.11.081] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/19/2003] [Indexed: 10/26/2022]
Abstract
Synaptic transmission between baroreceptor afferents and the nucleus tractus solitarius (NTS) is essential for reflex regulation of blood pressure. High frequency stimulation of the afferents in vivo leads to a decrease in synaptic strength and is generally attributed to reduction in presynaptic neurotransmitter release. It has been hypothesized that during high frequency stimulation glutamate a major neurotransmitter at the baroreceptor afferent terminals inhibits its own release via presynaptic group III metabotropic glutamate receptors (mGluRs). A key player in modulation of presynaptic release is vesicle exocytosis. The present study utilized cultured aortic baroreceptor neurons and the styryl dye FM2-10 to characterize (1) the dependence of exocytosis at these afferent nerve terminals on the frequency of neuronal activation, (2) the effect of duration of stimulation on the rate of exocytosis and (3) the role of mGluRs in the frequency-dependent modulation of exocytosis. Destaining in the FM2-10 loaded boutons during 3 min of stimulation, a measure of exocytosis, progressively decreased with increasing frequency (0.5, 1.0 and 10 Hz). Blockade of group III mGluRs with 300 microM (RS)-cyclopropyl-4-phosphonophenylglycine (CPPG) facilitated exocytosis evoked by 10 Hz stimulation but not at 0.5 Hz. The data suggest that aortic baroreceptor terminals exhibit frequency-dependent depression of exocytosis and support a role for group III mGluRs in the frequency-dependent modulation of exocytosis.
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MESH Headings
- Analysis of Variance
- Animals
- Animals, Newborn
- Aorta/innervation
- Carbocyanines/metabolism
- Cells, Cultured
- Dose-Response Relationship, Radiation
- Electric Stimulation/methods
- Exocytosis/drug effects
- Exocytosis/physiology
- Exocytosis/radiation effects
- Glycine/analogs & derivatives
- Glycine/pharmacology
- Microscopy, Fluorescence/methods
- Neurons, Afferent/physiology
- Neurons, Afferent/radiation effects
- Pressoreceptors/physiology
- Pressoreceptors/radiation effects
- Pyridinium Compounds/metabolism
- Quaternary Ammonium Compounds/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Metabotropic Glutamate/antagonists & inhibitors
- Receptors, Metabotropic Glutamate/drug effects
- Receptors, Metabotropic Glutamate/physiology
- Rosette Formation/methods
- Synapsins/metabolism
- Synaptic Vesicles/drug effects
- Synaptic Vesicles/physiology
- Synaptic Vesicles/radiation effects
- Time Factors
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Affiliation(s)
- Jaya Pamidimukkala
- Dalton Cardiovascular Research Center, Department of Veterinary Biomedical Sciences, University of Missouri-Columbia, 134 Research Park, Rm 219, Columbia, MO 65211, USA.
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48
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Baldwin ML, Rostas JAP, Sim ATR. Two modes of exocytosis from synaptosomes are differentially regulated by protein phosphatase types 2A and 2B. J Neurochem 2003; 85:1190-9. [PMID: 12753078 DOI: 10.1046/j.1471-4159.2003.01779.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The inhibitors okadaic acid (OA), fostriecin (FOS) and cyclosporin A (CsA), were used to investigate the roles of protein phosphatases in regulating exocytosis in rat brain synaptosomes by measuring glutamate release and the release of the styryl dye FM 2-10. Depolarization was induced by 30 mM KCl, or 0.3 mM or 1 mM 4-aminopyridine (4AP). OA and FOS produced a similar partial inhibition of KCl- and 0.3 mM 4AP- evoked exocytosis in both assays, but had little effect upon exocytosis evoked by 1 mM 4AP. In contrast, CsA had no effect upon KCl- and 0.3 mM 4AP-evoked exocytosis, but significantly enhanced glutamate release but not FM 2-10 dye release evoked by 1 mM 4AP. None of the phosphatase inhibitors changed calcium signals from FURA-2-loaded synaptosomes either before or after depolarization. Pretreatment with 100 nM phorbol 12-myristate 13-acetate abolished the inhibitory effect of OA on exocytosis induced by 0.3 mM 4AP. Taken together, these results show that exocytosis from synaptosomes has a phosphatase-sensitive and phosphatase-insensitive component, and that there are two modes of phosphatase-sensitive exocytosis that can be elicited by different depolarization conditions. Moreover, these two modes are differentially sensitive to phosphatase 2A and 2B.
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Affiliation(s)
- Monique L Baldwin
- School of Biomedical Sciences, University of Newcastle and Clinical Neuroscience Program, Hunter Medical Research Institute, Callaghan, New South Wales, Australia
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49
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Fukuda J, Ishimine H, Masaki Y. Long-term staining of live Merkel cells with FM dyes. Cell Tissue Res 2003; 311:325-32. [PMID: 12658440 DOI: 10.1007/s00441-002-0688-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2002] [Accepted: 11/26/2002] [Indexed: 10/25/2022]
Abstract
Live Merkel cells in the skin and hair follicles are known to incorporate a fluorescence dye, quinacrine, which has been utilized to identify and dissect the cells for experiments. Quinacrine fluorescence of the cells is, however, quickly lost and quinacrine-stained Merkel cells soon become difficult to identify in tissue culture. To find dyes that remain in the cells for a long period of time, we tested many fluorescence dyes and found that FM dyes (such as FM1-43) are useful markers for live Merkel cells. In the rat footpad skin, FM1-43 was shown to stain 95% of live Merkel cells that were already stained with quinacrine. FM4-64 stained 98% of quinacrine-stained Merkel cells. Merkel cells in sinus hair follicles were also stained with FM dyes. The fluorescence intensity of FM dyes was stronger than that of quinacrine, and the shape of the cells was more distinct in the FM-dye-stained cells. To test how long FM dyes remain in live cells, FM-dye-stained Merkel cells in hair follicles were embedded in collagen gel and were cultured in a serum-free medium. FM-dye-stained cells were easily identified even after 7 days of culture. During the culture, Merkel cells changed their shape, moved in the preparation and tended to aggregate on the surface. We conclude that FM dyes are powerful tools for tracing live Merkel cells in in vitro experiments. Moreover, the finding that Merkel cells incorporate FM dyes suggests that vesicles in the cells are likely to have mechanisms of recycling in a manner similar to those in neurons and secretory cells.
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Affiliation(s)
- Jun Fukuda
- Laboratory of Molecular and Cellular Physiology, Department of Physiology, National Defense Medical College of Japan, 3-2 Namiki, Tokorozawa, 359-8513, Saitama, Japan.
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50
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Guatimosim C, von Gersdorff H. Optical monitoring of synaptic vesicle trafficking in ribbon synapses. Neurochem Int 2002; 41:307-12. [PMID: 12176071 DOI: 10.1016/s0197-0186(02)00015-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Synaptic transmission constitutes the major basis of communication among nerve cells. Upon nerve terminal depolarisation, calcium influx triggers the exocytosis of synaptic vesicles at active zones. Vesicles are then retrieved by endocytosis, recycled and refilled with neurotransmitter. Fluorescent styryl dyes have proven very useful as tools for studying several aspects of the synaptic vesicle cycle. Here, we review recent imaging studies using styryl FM dyes and bipolar cells of goldfish retina, which have a giant synaptic terminal containing ribbon-type active zones. Optical techniques applied to this unique synaptic terminal have provided novel insights into the trafficking of synaptic vesicles during and following strong stimulation.
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