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Nowacka A, Getz AM, Bessa-Neto D, Choquet D. Activity-dependent diffusion trapping of AMPA receptors as a key step for expression of early LTP. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230220. [PMID: 38853553 PMCID: PMC11343219 DOI: 10.1098/rstb.2023.0220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Revised: 04/10/2024] [Accepted: 04/11/2024] [Indexed: 06/11/2024] Open
Abstract
This review focuses on the activity-dependent diffusion trapping of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) as a crucial mechanism for the expression of early long-term potentiation (LTP), a process central to learning and memory. Despite decades of research, the precise mechanisms by which LTP induction leads to an increase in AMPAR responses at synapses have been elusive. We review the different hypotheses that have been put forward to explain the increased AMPAR responsiveness during LTP. We discuss the dynamic nature of AMPAR complexes, including their constant turnover and activity-dependent modifications that affect their synaptic accumulation. We highlight a hypothesis suggesting that AMPARs are diffusively trapped at synapses through activity-dependent interactions with protein-based binding slots in the post-synaptic density (PSD), offering a potential explanation for the increased synaptic strength during LTP. Furthermore, we outline the challenges still to be addressed before we fully understand the functional roles and molecular mechanisms of AMPAR dynamic nanoscale organization in LTP. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Agata Nowacka
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, BordeauxF-33000, France
| | - Angela M. Getz
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, BordeauxF-33000, France
- University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4, BordeauxF-33000, France
| | - Diogo Bessa-Neto
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, BordeauxF-33000, France
| | - Daniel Choquet
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, BordeauxF-33000, France
- University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4, BordeauxF-33000, France
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2
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Stockwell I, Watson JF, Greger IH. Tuning synaptic strength by regulation of AMPA glutamate receptor localization. Bioessays 2024; 46:e2400006. [PMID: 38693811 PMCID: PMC7616278 DOI: 10.1002/bies.202400006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/19/2024] [Accepted: 04/23/2024] [Indexed: 05/03/2024]
Abstract
Long-term potentiation (LTP) of excitatory synapses is a leading model to explain the concept of information storage in the brain. Multiple mechanisms contribute to LTP, but central amongst them is an increased sensitivity of the postsynaptic membrane to neurotransmitter release. This sensitivity is predominantly determined by the abundance and localization of AMPA-type glutamate receptors (AMPARs). A combination of AMPAR structural data, super-resolution imaging of excitatory synapses, and an abundance of electrophysiological studies are providing an ever-clearer picture of how AMPARs are recruited and organized at synaptic junctions. Here, we review the latest insights into this process, and discuss how both cytoplasmic and extracellular receptor elements cooperate to tune the AMPAR response at the hippocampal CA1 synapse.
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Affiliation(s)
- Imogen Stockwell
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Jake F. Watson
- Institute of Science and Technology, Technology (IST) Austria, Klosterneuburg, Austria
| | - Ingo H. Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
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3
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Sachs S, Reinhard S, Eilts J, Sauer M, Werner C. Visualizing the trans-synaptic arrangement of synaptic proteins by expansion microscopy. Front Cell Neurosci 2024; 18:1328726. [PMID: 38486709 PMCID: PMC10937466 DOI: 10.3389/fncel.2024.1328726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 02/13/2024] [Indexed: 03/17/2024] Open
Abstract
High fidelity synaptic neurotransmission in the millisecond range is provided by a defined structural arrangement of synaptic proteins. At the presynapse multi-epitope scaffolding proteins are organized spatially at release sites to guarantee optimal binding of neurotransmitters at receptor clusters. The organization of pre- and postsynaptic proteins in trans-synaptic nanocolumns would thus intuitively support efficient information transfer at the synapse. Visualization of these protein-dense regions as well as the minute size of protein-packed synaptic clefts remains, however, challenging. To enable efficient labeling of these protein complexes, we developed post-gelation immunolabeling expansion microscopy combined with Airyscan super-resolution microscopy. Using ~8-fold expanded samples, Airyscan enables multicolor fluorescence imaging with 20-40 nm spatial resolution. Post-immunolabeling of decrowded (expanded) samples provides increased labeling efficiency and allows the visualization of trans-synaptic nanocolumns. Our approach is ideally suited to investigate the pathological impact on nanocolumn arrangement e.g., in limbic encephalitis with autoantibodies targeting trans-synaptic leucine-rich glioma inactivated 1 protein (LGI1).
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Affiliation(s)
| | | | | | | | - Christian Werner
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
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4
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Willig KI. In vivo super-resolution of the brain - How to visualize the hidden nanoplasticity? iScience 2022; 25:104961. [PMID: 36093060 PMCID: PMC9449647 DOI: 10.1016/j.isci.2022.104961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Super-resolution fluorescence microscopy has entered most biological laboratories worldwide and its benefit is undisputable. Its application to brain imaging, for example in living mice, enables the study of sub-cellular structural plasticity and brain function directly in a living mammal. The demands of brain imaging on the different super-resolution microscopy techniques (STED, RESOLFT, SIM, ISM) and labeling strategies are discussed here as well as the challenges of the required cranial window preparation. Applications of super-resolution in the anesthetized mouse brain enlighten the stability and plasticity of synaptic nanostructures. These studies show the potential of in vivo super-resolution imaging and justify its application more widely in vivo to investigate the role of nanostructures in memory and learning.
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Affiliation(s)
- Katrin I Willig
- Group of Optical Nanoscopy in Neuroscience, Max Planck Institute for Multidisciplinary Sciences, City Campus, Göttingen, Germany
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5
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Yu Q, Kumata K, Rong J, Chen Z, Yamasaki T, Chen J, Xiao Z, Ishii H, Hiraishi A, Shao T, Zhang Y, Hu K, Xie L, Fujinaga M, Zhao C, Mori W, Collier T, Haider A, Tomita S, Zhang MR, Liang S. Imaging of Transmembrane AMPA Receptor Regulatory Proteins by Positron Emission Tomography. J Med Chem 2022; 65:9144-9158. [PMID: 35762919 PMCID: PMC10448436 DOI: 10.1021/acs.jmedchem.2c00377] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The transmembrane α-amino-3-hydroxyl-5-methyl-4-isoxazolepropionic acid (AMPA) receptor regulatory protein γ-8 (TARP γ-8) constitutes an auxiliary subunit of AMPA receptors, which mediates various brain functions including learning and memory. TARP γ-8 has emerged as a promising therapeutic target for central nervous system disorders. Despite considerable efforts, previously reported TARP γ-8 PET radioligands, such as [11C]TARP-1903 and [11C]TARP-1811 series, were plagued by limited brain uptake and/or high nonspecific binding in vivo. Herein, we developed two novel 11C-labeled probes, [11C]8 and [11C]15 (also named as [11C]TARP-2105), of which the latter exhibited a reasonable brain uptake as well as specific binding toward TARP γ-8 both in vitro and in vivo, as confirmed by blocking experiments with the commercially available TARP γ-8 inhibitor, JNJ-55511118 in the TARP γ-8-rich hippocampus. Overall, [11C]15 exhibited promising tracer characteristics and proved to be a lead positron-emission tomography ligand for the non-invasive quantification of TARP γ-8 in the mammalian brain.
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Affiliation(s)
- Qingzhen Yu
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
- Medical Research Center, Southern University of Science and Technology Hospital & School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Katsushi Kumata
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Zhen Chen
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Tomoteru Yamasaki
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Jiahui Chen
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Zhiwei Xiao
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Hideki Ishii
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Atsuto Hiraishi
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Tuo Shao
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Yiding Zhang
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Kuan Hu
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Lin Xie
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Masayuki Fujinaga
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Chunyu Zhao
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Wakana Mori
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Thomas Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Ahmed Haider
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
| | - Susumu Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, United States
| | - Ming-Rong Zhang
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Steven Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, United States
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6
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Wegner W, Steffens H, Gregor C, Wolf F, Willig KI. Environmental enrichment enhances patterning and remodeling of synaptic nanoarchitecture as revealed by STED nanoscopy. eLife 2022; 11:73603. [PMID: 35195066 PMCID: PMC8903838 DOI: 10.7554/elife.73603] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 02/22/2022] [Indexed: 12/04/2022] Open
Abstract
Synaptic plasticity underlies long-lasting structural and functional changes to brain circuitry and its experience-dependent remodeling can be fundamentally enhanced by environmental enrichment. It is however unknown, whether and how the environmental enrichment alters the morphology and dynamics of individual synapses. Here, we present a virtually crosstalk-free two-color in vivo stimulated emission depletion (STED) microscope to simultaneously superresolve the dynamics of endogenous PSD95 of the post-synaptic density and spine geometry in the mouse cortex. In general, the spine head geometry and PSD95 assemblies were highly dynamic, their changes depended linearly on their original size but correlated only mildly. With environmental enrichment, the size distributions of PSD95 and spine head sizes were sharper than in controls, indicating that synaptic strength is set more uniformly. The topography of the PSD95 nanoorganization was more dynamic after environmental enrichment; changes in size were smaller but more correlated than in mice housed in standard cages. Thus, two-color in vivo time-lapse imaging of synaptic nanoorganization uncovers a unique synaptic nanoplasticity associated with the enhanced learning capabilities under environmental enrichment.
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Affiliation(s)
- Waja Wegner
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
| | - Heinz Steffens
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
| | - Carola Gregor
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Fred Wolf
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - Katrin I Willig
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
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7
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Delgado JY. Lack of support for surface diffusion of postsynaptic AMPARs in tuning synaptic transmission. Biophys J 2021; 120:3409-3417. [PMID: 34214532 DOI: 10.1016/j.bpj.2021.06.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/19/2021] [Accepted: 06/17/2021] [Indexed: 10/21/2022] Open
Abstract
Repetitive stimulation of excitatory synapses triggers molecular events required for signal transfer across neuronal synapses. It has been hypothesized that one of these molecular events, the diffusion of extrasynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPARs) (i.e., the diffusion hypothesis), is necessary to help synapses recover from paired-pulse depression. To examine this presumed role of AMPAR diffusion during repetitive presynaptic stimulation, a biophysical model based on published physiological results was developed to track the localization and gating of each AMPAR. The model demonstrates that AMPAR gating in short intervals of fewer than 100 ms is controlled by their position in relation to the glutamate release site and by their recovery from desensitization, but it is negligibly influenced by their diffusion. Therefore, these simulations failed to demonstrate a role for AMPAR diffusion in helping synapses recover from paired-pulse depression.
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Affiliation(s)
- Jary Y Delgado
- Department of Biology, University of Chicago, Chicago, Illinois.
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8
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Compans B, Camus C, Kallergi E, Sposini S, Martineau M, Butler C, Kechkar A, Klaassen RV, Retailleau N, Sejnowski TJ, Smit AB, Sibarita JB, Bartol TM, Perrais D, Nikoletopoulou V, Choquet D, Hosy E. NMDAR-dependent long-term depression is associated with increased short term plasticity through autophagy mediated loss of PSD-95. Nat Commun 2021; 12:2849. [PMID: 33990590 PMCID: PMC8121912 DOI: 10.1038/s41467-021-23133-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 04/07/2021] [Indexed: 01/27/2023] Open
Abstract
Long-term depression (LTD) of synaptic strength can take multiple forms and contribute to circuit remodeling, memory encoding or erasure. The generic term LTD encompasses various induction pathways, including activation of NMDA, mGlu or P2X receptors. However, the associated specific molecular mechanisms and effects on synaptic physiology are still unclear. We here compare how NMDAR- or P2XR-dependent LTD affect synaptic nanoscale organization and function in rodents. While both LTDs are associated with a loss and reorganization of synaptic AMPARs, only NMDAR-dependent LTD induction triggers a profound reorganization of PSD-95. This modification, which requires the autophagy machinery to remove the T19-phosphorylated form of PSD-95 from synapses, leads to an increase in AMPAR surface mobility. We demonstrate that these post-synaptic changes that occur specifically during NMDAR-dependent LTD result in an increased short-term plasticity improving neuronal responsiveness of depressed synapses. Our results establish that P2XR- and NMDAR-mediated LTD are associated to functionally distinct forms of LTD.
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Affiliation(s)
- Benjamin Compans
- Interdisciplinary Institute for Neuroscience, CNRS, Univ. Bordeaux, IINS, UMR 5297, Bordeaux, France
| | - Come Camus
- Interdisciplinary Institute for Neuroscience, CNRS, Univ. Bordeaux, IINS, UMR 5297, Bordeaux, France
| | - Emmanouela Kallergi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Silvia Sposini
- Interdisciplinary Institute for Neuroscience, CNRS, Univ. Bordeaux, IINS, UMR 5297, Bordeaux, France
| | - Magalie Martineau
- Interdisciplinary Institute for Neuroscience, CNRS, Univ. Bordeaux, IINS, UMR 5297, Bordeaux, France
| | - Corey Butler
- Interdisciplinary Institute for Neuroscience, CNRS, Univ. Bordeaux, IINS, UMR 5297, Bordeaux, France
| | - Adel Kechkar
- Interdisciplinary Institute for Neuroscience, CNRS, Univ. Bordeaux, IINS, UMR 5297, Bordeaux, France
| | - Remco V Klaassen
- Department Molecular and Cellular Neurobiology, Amsterdam, HV, The Netherlands
| | - Natacha Retailleau
- Interdisciplinary Institute for Neuroscience, CNRS, Univ. Bordeaux, IINS, UMR 5297, Bordeaux, France
| | - Terrence J Sejnowski
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - August B Smit
- Department Molecular and Cellular Neurobiology, Amsterdam, HV, The Netherlands
| | - Jean-Baptiste Sibarita
- Interdisciplinary Institute for Neuroscience, CNRS, Univ. Bordeaux, IINS, UMR 5297, Bordeaux, France
| | - Thomas M Bartol
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - David Perrais
- Interdisciplinary Institute for Neuroscience, CNRS, Univ. Bordeaux, IINS, UMR 5297, Bordeaux, France
| | | | - Daniel Choquet
- Interdisciplinary Institute for Neuroscience, CNRS, Univ. Bordeaux, IINS, UMR 5297, Bordeaux, France
- Univ. Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, Bordeaux, France
| | - Eric Hosy
- Interdisciplinary Institute for Neuroscience, CNRS, Univ. Bordeaux, IINS, UMR 5297, Bordeaux, France.
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9
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The importance of ultrastructural analysis of memory. Brain Res Bull 2021; 173:28-36. [PMID: 33984429 DOI: 10.1016/j.brainresbull.2021.04.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/19/2021] [Accepted: 04/22/2021] [Indexed: 11/22/2022]
Abstract
Plasticity of glutamatergic synapses in the hippocampus is believed to underlie learning and memory processes. Surprisingly, very few studies report long-lasting structural changes of synapses induced by behavioral training. It remains, therefore, unclear which synaptic changes in the hippocampus contribute to memory storage. Here, we systematically compare how long-term potentiation of synaptic transmission (LTP) (a primary form of synaptic plasticity and cellular model of memory) and behavioral training affect hippocampal glutamatergic synapses at the ultrastructural level enabled by electron microscopy. The review of the literature indicates that while LTP induces growth of dendritic spines and post-synaptic densities (PSD), that represent postsynaptic part of a glutamatergic synapse, after behavioral training there is transient (< 6 h) synaptogenesis and long-lasting (> 24 h) increase in PSD volume (without a significant change of dendritic spine volume), indicating that training-induced PSD growth may reflect long-term enhancement of synaptic functions. Additionally, formation of multi-innervated spines (MIS), is associated with long-term memory in aged mice and LTP-deficient mutant mice. Since volume of PSD, as well as atypical synapses, can be reliably observed only with electron microscopy, we argue that the ultrastructural level of analysis is required to reveal synaptic changes that are associated with long-term storage of information in the brain.
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10
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Becker MFP, Tetzlaff C. The biophysical basis underlying the maintenance of early phase long-term potentiation. PLoS Comput Biol 2021; 17:e1008813. [PMID: 33750943 PMCID: PMC8016278 DOI: 10.1371/journal.pcbi.1008813] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 04/01/2021] [Accepted: 02/17/2021] [Indexed: 11/18/2022] Open
Abstract
The maintenance of synaptic changes resulting from long-term potentiation (LTP) is essential for brain function such as memory and learning. Different LTP phases have been associated with diverse molecular processes and pathways, and the molecular underpinnings of LTP on the short, as well as long time scales, are well established. However, the principles on the intermediate time scale of 1-6 hours that mediate the early phase of LTP (E-LTP) remain elusive. We hypothesize that the interplay between specific features of postsynaptic receptor trafficking is responsible for sustaining synaptic changes during this LTP phase. We test this hypothesis by formalizing a biophysical model that integrates several experimentally-motivated mechanisms. The model captures a wide range of experimental findings and predicts that synaptic changes are preserved for hours when the receptor dynamics are shaped by the interplay of structural changes of the spine in conjunction with increased trafficking from recycling endosomes and the cooperative binding of receptors. Furthermore, our model provides several predictions to verify our findings experimentally.
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Affiliation(s)
- Moritz F. P. Becker
- III. Institute of Physics – Biophysics, Georg-August University, Göttingen, Germany
| | - Christian Tetzlaff
- III. Institute of Physics – Biophysics, Georg-August University, Göttingen, Germany
- Bernstein Center for Computational Neuroscience, Göttingen, Germany
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11
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Calebiro D, Koszegi Z, Lanoiselée Y, Miljus T, O'Brien S. G protein-coupled receptor-G protein interactions: a single-molecule perspective. Physiol Rev 2020; 101:857-906. [PMID: 33331229 DOI: 10.1152/physrev.00021.2020] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
G protein-coupled receptors (GPCRs) regulate many cellular and physiological processes, responding to a diverse range of extracellular stimuli including hormones, neurotransmitters, odorants, and light. Decades of biochemical and pharmacological studies have provided fundamental insights into the mechanisms of GPCR signaling. Thanks to recent advances in structural biology, we now possess an atomistic understanding of receptor activation and G protein coupling. However, how GPCRs and G proteins interact in living cells to confer signaling efficiency and specificity remains insufficiently understood. The development of advanced optical methods, including single-molecule microscopy, has provided the means to study receptors and G proteins in living cells with unprecedented spatio-temporal resolution. The results of these studies reveal an unexpected level of complexity, whereby GPCRs undergo transient interactions among themselves as well as with G proteins and structural elements of the plasma membrane to form short-lived signaling nanodomains that likely confer both rapidity and specificity to GPCR signaling. These findings may provide new strategies to pharmaceutically modulate GPCR function, which might eventually pave the way to innovative drugs for common diseases such as diabetes or heart failure.
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Affiliation(s)
- Davide Calebiro
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Zsombor Koszegi
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Yann Lanoiselée
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Tamara Miljus
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Shannon O'Brien
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
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12
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Combining Single Molecule Super-Resolution Imaging Techniques to Unravel the Nanoscale Organization of the Presynapse. Methods Mol Biol 2020. [PMID: 33222141 DOI: 10.1007/978-1-0716-1044-2_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
The fusion of synaptic vesicles with the plasma membrane underpins neurotransmission. A number of presynaptic proteins play a critical role in overcoming the energy barrier inherent to the fusion of the negatively charged vesicular and plasma membranes. Emerging concepts suggest that this process is hierarchical and dependent on rapid and transient reorganization of proteins in and out of small nanoclusters located in the active zones of nerve terminals. Examining the nanoscale organization of presynaptic molecules requires super-resolution microscopy to overcome the limits of conventional light microscopy. In this chapter, we describe three super-resolution techniques that allow for the examination of the nanoscale organization of proteins within live hippocampal nerve terminals. We used (1) single-particle tracking photoactivated localization microscopy (sptPALM) to resolve the mobility and clustering of syntaxin1A (STX1A), (2) universal Point Accumulation Imaging in Nanoscale Topography (uPAINT) to study the mobility of a pool of vesicular-associated membrane protein 2 (VAMP2) transiting on the plasma membrane, and (3) subdiffractional Tracking of Internalized Molecules (sdTIM) to track VAMP2-positive recycling synaptic vesicles in conjunction with Cholera Toxin subunit B (CTB), which has recently been shown to be trafficked retrogradely from the presynapse to the cell body via signaling endosomes.
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13
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Galantamine-Memantine combination in the treatment of Alzheimer's disease and beyond. Psychiatry Res 2020; 293:113409. [PMID: 32829072 DOI: 10.1016/j.psychres.2020.113409] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/17/2020] [Accepted: 08/17/2020] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease (AD) is the most prevalent form of dementia in the elderly population worldwide. Despite the major unmet clinical need, no new medications for the treatment of AD have been approved since 2003. Galantamine is an acetylcholinesterase inhibitor that is also a positive allosteric modulator at the α4β2 and α7nACh receptors. Memantine is an N-methyl-d-aspartate receptor modulator/agonist. Both galantamine and memantine are FDA-approved medications for the treatment of AD. The objective of this review is to highlight the potential of the galantamine-memantine combination to conduct randomized controlled trials (RCTs) in AD. Several studies have shown the combination to be effective. Neurodegenerative diseases involve multiple pathologies; therefore, combination treatment appears to be a rational approach. Although underutilized, the galantamine-memantine combination is the standard of care in the treatment of AD. Positive RCTs with the combination with concurrent improvement in symptoms and biomarkers may lead to FDA approval, which may lead to greater utilization of this combination in clinical practice.
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14
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Kleindienst D, Montanaro J, Bhandari P, Case MJ, Fukazawa Y, Shigemoto R. Deep Learning-Assisted High-Throughput Analysis of Freeze-Fracture Replica Images Applied to Glutamate Receptors and Calcium Channels at Hippocampal Synapses. Int J Mol Sci 2020; 21:E6737. [PMID: 32937911 PMCID: PMC7555218 DOI: 10.3390/ijms21186737] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/07/2020] [Accepted: 09/10/2020] [Indexed: 12/15/2022] Open
Abstract
The molecular anatomy of synapses defines their characteristics in transmission and plasticity. Precise measurements of the number and distribution of synaptic proteins are important for our understanding of synapse heterogeneity within and between brain regions. Freeze-fracture replica immunogold electron microscopy enables us to analyze them quantitatively on a two-dimensional membrane surface. Here, we introduce Darea software, which utilizes deep learning for analysis of replica images and demonstrate its usefulness for quick measurements of the pre- and postsynaptic areas, density and distribution of gold particles at synapses in a reproducible manner. We used Darea for comparing glutamate receptor and calcium channel distributions between hippocampal CA3-CA1 spine synapses on apical and basal dendrites, which differ in signaling pathways involved in synaptic plasticity. We found that apical synapses express a higher density of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors and a stronger increase of AMPA receptors with synaptic size, while basal synapses show a larger increase in N-methyl-D-aspartate (NMDA) receptors with size. Interestingly, AMPA and NMDA receptors are segregated within postsynaptic sites and negatively correlated in density among both apical and basal synapses. In the presynaptic sites, Cav2.1 voltage-gated calcium channels show similar densities in apical and basal synapses with distributions consistent with an exclusion zone model of calcium channel-release site topography.
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Affiliation(s)
- David Kleindienst
- Institute of Science and Technology (IST )Austria, 3400 Klosterneuburg, Austria; (J.M.); (P.B.); (M.J.C.)
| | - Jacqueline Montanaro
- Institute of Science and Technology (IST )Austria, 3400 Klosterneuburg, Austria; (J.M.); (P.B.); (M.J.C.)
| | - Pradeep Bhandari
- Institute of Science and Technology (IST )Austria, 3400 Klosterneuburg, Austria; (J.M.); (P.B.); (M.J.C.)
| | - Matthew J. Case
- Institute of Science and Technology (IST )Austria, 3400 Klosterneuburg, Austria; (J.M.); (P.B.); (M.J.C.)
| | - Yugo Fukazawa
- Department of Histological and Physiological Sciences, Faculty of Medical Science, University of Fukui, Yoshida, Fukui 910-1193, Japan;
| | - Ryuichi Shigemoto
- Institute of Science and Technology (IST )Austria, 3400 Klosterneuburg, Austria; (J.M.); (P.B.); (M.J.C.)
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15
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AMPA receptor nanoscale dynamic organization and synaptic plasticities. Curr Opin Neurobiol 2020; 63:137-145. [DOI: 10.1016/j.conb.2020.04.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/28/2020] [Accepted: 04/13/2020] [Indexed: 12/13/2022]
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16
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Glasgow SD, McPhedrain R, Madranges JF, Kennedy TE, Ruthazer ES. Approaches and Limitations in the Investigation of Synaptic Transmission and Plasticity. Front Synaptic Neurosci 2019; 11:20. [PMID: 31396073 PMCID: PMC6667546 DOI: 10.3389/fnsyn.2019.00020] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/04/2019] [Indexed: 12/16/2022] Open
Abstract
The numbers and strengths of synapses in the brain change throughout development, and even into adulthood, as synaptic inputs are added, eliminated, and refined in response to ongoing neural activity. A number of experimental techniques can assess these changes, including single-cell electrophysiological recording which offers measurements of synaptic inputs with high temporal resolution. Coupled with electrical stimulation, photoactivatable opsins, and caged compounds, to facilitate fine spatiotemporal control over release of neurotransmitters, electrophysiological recordings allow for precise dissection of presynaptic and postsynaptic mechanisms of action. Here, we discuss the strengths and pitfalls of various techniques commonly used to analyze synapses, including miniature excitatory/inhibitory (E/I) postsynaptic currents, evoked release, and optogenetic stimulation. Together, these techniques can provide multiple lines of convergent evidence to generate meaningful insight into the emergence of circuit connectivity and maturation. A full understanding of potential caveats and alternative explanations for findings is essential to avoid data misinterpretation.
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Affiliation(s)
| | | | | | | | - Edward S. Ruthazer
- Department of Neurology & Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal, QC, Canada
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17
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Calebiro D, Koszegi Z. The subcellular dynamics of GPCR signaling. Mol Cell Endocrinol 2019; 483:24-30. [PMID: 30610913 DOI: 10.1016/j.mce.2018.12.020] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 12/26/2018] [Accepted: 12/27/2018] [Indexed: 01/20/2023]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of membrane receptors and mediate the effects of a multitude of extracellular cues, such as hormones, neurotransmitters, odorants and light. Because of their involvement in numerous physiological and pathological processes and their accessibility, they are extensively exploited as pharmacological targets. Biochemical and structural biology investigations have clarified the molecular basis of GPCR signaling to a high level of detail. In spite of this, how GPCRs can efficiently and precisely translate extracellular signals into specific and well-orchestrated biological responses in the complexity of a living cell or organism remains insufficiently understood. To explain the high efficiency and specificity observed in GPCR signaling, it has been suggested that GPCR might signal in discrete nanodomains on the plasma membrane or even form stable complexes with G proteins and effectors. However, directly testing these hypotheses has proven a major challenge. Recent studies taking advantage of innovative optical methods such as fluorescence resonance energy transfer (FRET) and single-molecule microscopy have begun to dig into the organization of GPCR signaling in living cells on the spatial (nm) and temporal (ms) scales on which cell signaling events are taking place. The results of these studies are revealing a complex and highly dynamic picture, whereby GPCRs undergo transient interaction with their signaling partners, membrane lipids and the cytoskeleton to form short-lived signaling nanodomains both on the plasma membrane and at intracellular sites. Continuous exchanges among such nanodomains via later diffusion as well as via membrane trafficking might provide a highly sophisticated way of controlling the timing and location of GPCR signaling. Here, we will review the most recent advances in our understanding of the organization of GPCR signaling in living cells, with a particular focus on its dynamics.
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Affiliation(s)
- Davide Calebiro
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, UK.
| | - Zsombor Koszegi
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, UK
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18
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Fu H, Chen Z, Josephson L, Li Z, Liang SH. Positron Emission Tomography (PET) Ligand Development for Ionotropic Glutamate Receptors: Challenges and Opportunities for Radiotracer Targeting N-Methyl-d-aspartate (NMDA), α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA), and Kainate Receptors. J Med Chem 2019; 62:403-419. [PMID: 30110164 PMCID: PMC6393217 DOI: 10.1021/acs.jmedchem.8b00714] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Ionotropic glutamate receptors (iGluRs) mediate excitatory neurotransmission within the mammalian central nervous system. iGluRs exist as three main groups: N-methyl-d-aspartate receptors (NMDARs), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs), and kainate receptors. The past decades have witnessed a remarkable development of PET tracers targeting different iGluRs including NMDARs and AMPARs, and several of the tracers have advanced to clinical imaging studies. Here, we assess the recent development of iGluR PET probes, focusing on tracer design, brain kinetics, and performance in PET imaging studies. Furthermore, this review will not only present challenges in the tracer development but also provide novel approaches in conjunction with most recent drug discovery efforts on these iGluRs, including subtype-selective NMDAR and transmembrane AMPAR regulatory protein modulators and positive allosteric modulators (PAMs) of AMPARs. These approaches, if successful as PET tracers, may provide fundamental knowledge to understand the roles of iGluR receptors under physiological and pathological conditions.
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Affiliation(s)
- Hualong Fu
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
| | - Zhen Chen
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
| | - Zijing Li
- State Key Laboratory of Molecular Vaccinology, Molecular Diagnosis & Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, Xiamen 361102, P. R. China
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
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19
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Park M. AMPA Receptor Trafficking for Postsynaptic Potentiation. Front Cell Neurosci 2018; 12:361. [PMID: 30364291 PMCID: PMC6193507 DOI: 10.3389/fncel.2018.00361] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 09/25/2018] [Indexed: 01/25/2023] Open
Abstract
Long-term potentiation (LTP) of excitatory synaptic strength, which has long been considered a synaptic correlate for learning and memory, requires a fast recruitment of additional α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors (AMPARs) to the postsynaptic sites. As cell biological concepts have been applied to the field and genetic manipulation and microscopic imaging technologies have been advanced, visualization of the trafficking of AMPARs to synapses for LTP has been investigated intensively over the last decade. Recycling endosomes have been reported as intracellular storage organelles to supply AMPARs for LTP through the endocytic recycling pathway. In addition, exocytic domains in the spine plasma membrane, where AMPARs are inserted from the intracellular compartment, and nanodomains, where diffusing AMPARs are trapped and immobilized inside synapses for LTP, have been described. Furthermore, cell surface lateral diffusion of AMPARs from extrasynaptic to synaptic sites has been reported as a key step for AMPAR location to the synaptic sites for LTP. This review article will discuss recent findings and views on the reservoir(s) of AMPARs and their trafficking for LTP expression by focusing on the exocytosis and lateral diffusion of AMPARs, and provide some future directions that need to be addressed in the field of LTP.
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Affiliation(s)
- Mikyoung Park
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea.,Department of Neuroscience, Korea University of Science and Technology, Daejeon, South Korea
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20
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Chen Z, Mori W, Zhang X, Yamasaki T, Dunn PJ, Zhang G, Fu H, Shao T, Zhang Y, Hatori A, Ma L, Fujinaga M, Xie L, Deng X, Li H, Yu Q, Rong J, Josephson L, Ma JA, Shao Y, Tomita S, Zhang MR, Liang SH. Synthesis, pharmacology and preclinical evaluation of 11C-labeled 1,3-dihydro-2H-benzo[d]imidazole-2-ones for imaging γ8-dependent transmembrane AMPA receptor regulatory protein. Eur J Med Chem 2018; 157:898-908. [PMID: 30145376 DOI: 10.1016/j.ejmech.2018.08.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/04/2018] [Accepted: 08/06/2018] [Indexed: 11/20/2022]
Abstract
a-Amino-3-hydroxyl-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are implicated in the pathology of neurological diseases such as epilepsy and schizophrenia. As pan antagonists for this target are often accompanied with undesired effects at high doses, one of the recent drug discovery approaches has shifted to subtype-selective AMPA receptor (AMPAR) antagonists, specifically, via modulating transmembrane AMPAR regulatory proteins (TARPs). The quantification of AMPARs by positron emission tomography (PET) would help obtain insights into disease conditions in the living brain and advance the translational development of AMPAR antagonists. Herein we report the design, synthesis and preclinical evaluation of a series of TARP γ-8 antagonists, amenable for radiolabeling, for the development of subtype-selective AMPAR PET imaging agents. Based on the pharmacology evaluation, molecular docking studies and physiochemical properties, we have identified several promising lead compounds 3, 17-19 and 21 for in vivo PET studies. All candidate compounds were labeled with [11C]COCl2 in high radiochemical yields (13-31% RCY) and high molar activities (35-196 GBq/μmol). While tracers 30 ([11C]17) &32 ([11C]21) crossed the blood-brain barrier and showed heterogeneous distribution in PET studies, consistent with TARP γ-8 expression, high nonspecific binding prevented further evaluation. To our delight, tracer 31 ([11C]3) showed good in vitro specific binding and characteristic high uptake in the hippocampus in rat brain tissues, which provides the guideline for further development of a new generation subtype selective TARP γ-8 dependent AMPAR tracers.
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Affiliation(s)
- Zhen Chen
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA; Department of Chemistry, School of Science, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China
| | - Wakana Mori
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Xiaofei Zhang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Tomoteru Yamasaki
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Patrick J Dunn
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Genwei Zhang
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, 73019, USA
| | - Hualong Fu
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Tuo Shao
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Yiding Zhang
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Akiko Hatori
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Longle Ma
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Masayuki Fujinaga
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Lin Xie
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan
| | - Xiaoyun Deng
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Hua Li
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Qingzhen Yu
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Jun-An Ma
- Department of Chemistry, School of Science, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China
| | - Yihan Shao
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, 73019, USA
| | - Susumu Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Ming-Rong Zhang
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, 263-8555, Japan.
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA.
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21
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Haas KT, Compans B, Letellier M, Bartol TM, Grillo-Bosch D, Sejnowski TJ, Sainlos M, Choquet D, Thoumine O, Hosy E. Pre-post synaptic alignment through neuroligin-1 tunes synaptic transmission efficiency. eLife 2018; 7:e31755. [PMID: 30044218 PMCID: PMC6070337 DOI: 10.7554/elife.31755] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 07/24/2018] [Indexed: 12/25/2022] Open
Abstract
The nanoscale organization of neurotransmitter receptors regarding pre-synaptic release sites is a fundamental determinant of the synaptic transmission amplitude and reliability. How modifications in the pre- and post-synaptic machinery alignments affects synaptic currents, has only been addressed with computer modelling. Using single molecule super-resolution microscopy, we found a strong spatial correlation between AMPA receptor (AMPAR) nanodomains and the post-synaptic adhesion protein neuroligin-1 (NLG1). Expression of a truncated form of NLG1 disrupted this correlation without affecting the intrinsic AMPAR organization, shifting the pre-synaptic release machinery away from AMPAR nanodomains. Electrophysiology in dissociated and organotypic hippocampal rodent cultures shows these treatments significantly decrease AMPAR-mediated miniature and EPSC amplitudes. Computer modelling predicts that ~100 nm lateral shift between AMPAR nanoclusters and glutamate release sites induces a significant reduction in AMPAR-mediated currents. Thus, our results suggest the synapses necessity to release glutamate precisely in front of AMPAR nanodomains, to maintain a high synaptic responses efficiency.
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Affiliation(s)
- Kalina T Haas
- Interdisciplinary Institute for NeuroscienceUniversity of Bordeaux, UMR 5297, F-33000BordeauxFrance
- Interdisciplinary Institute for NeuroscienceCNRS, UMR 5297, F-33000BordeauxFrance
| | - Benjamin Compans
- Interdisciplinary Institute for NeuroscienceUniversity of Bordeaux, UMR 5297, F-33000BordeauxFrance
- Interdisciplinary Institute for NeuroscienceCNRS, UMR 5297, F-33000BordeauxFrance
| | - Mathieu Letellier
- Interdisciplinary Institute for NeuroscienceUniversity of Bordeaux, UMR 5297, F-33000BordeauxFrance
- Interdisciplinary Institute for NeuroscienceCNRS, UMR 5297, F-33000BordeauxFrance
| | - Thomas M Bartol
- Howard Hughes Medical InstituteSalk Institute for Biological StudiesLa JollaUnited States
| | - Dolors Grillo-Bosch
- Interdisciplinary Institute for NeuroscienceUniversity of Bordeaux, UMR 5297, F-33000BordeauxFrance
- Interdisciplinary Institute for NeuroscienceCNRS, UMR 5297, F-33000BordeauxFrance
| | - Terrence J Sejnowski
- Howard Hughes Medical InstituteSalk Institute for Biological StudiesLa JollaUnited States
| | - Matthieu Sainlos
- Interdisciplinary Institute for NeuroscienceUniversity of Bordeaux, UMR 5297, F-33000BordeauxFrance
- Interdisciplinary Institute for NeuroscienceCNRS, UMR 5297, F-33000BordeauxFrance
| | - Daniel Choquet
- Interdisciplinary Institute for NeuroscienceUniversity of Bordeaux, UMR 5297, F-33000BordeauxFrance
- Interdisciplinary Institute for NeuroscienceCNRS, UMR 5297, F-33000BordeauxFrance
- Bordeaux Imaging CenterUMS 3420 CNRS, Université de Bordeaux, US4 INSERM, F-33000BordeauxFrance
| | - Olivier Thoumine
- Interdisciplinary Institute for NeuroscienceUniversity of Bordeaux, UMR 5297, F-33000BordeauxFrance
- Interdisciplinary Institute for NeuroscienceCNRS, UMR 5297, F-33000BordeauxFrance
| | - Eric Hosy
- Interdisciplinary Institute for NeuroscienceUniversity of Bordeaux, UMR 5297, F-33000BordeauxFrance
- Interdisciplinary Institute for NeuroscienceCNRS, UMR 5297, F-33000BordeauxFrance
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22
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Delgado JY, Selvin PR. A Revised View on the Role of Surface AMPAR Mobility in Tuning Synaptic Transmission: Limitations, Tools, and Alternative Views. Front Synaptic Neurosci 2018; 10:21. [PMID: 30079019 PMCID: PMC6062754 DOI: 10.3389/fnsyn.2018.00021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 06/27/2018] [Indexed: 12/21/2022] Open
Abstract
Calcium dynamics in presynaptic terminals regulate the response dynamics of most central excitatory synapses. However, this dogma has been challenged by the hypothesis that mobility of the postsynaptic alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid subtype glutamate receptors (AMPAR) plays a role in tuning fast excitatory synaptic transmission. In this review, we reevaluate the factors regulating postsynaptic AMPAR mobility, reassess the modeling parameters, analyze the experimental tools, and end by providing alternative ideas stemming from recent results. In particular, newer methods of labeling AMPARs with small fluorophores in live neurons, combined with super-resolution microscopy and sub-second dynamics, lends support to the idea that AMPARs are primarily within the synapse, are greatly constrained, and have much slower mobility than previously thought. We discuss new experiments which may be necessary to readdress the role of postsynaptic AMPAR mobility in tuning fast excitatory synaptic transmission.
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Affiliation(s)
- Jary Y Delgado
- Department of Neurobiology, The University of Chicago, Chicago, IL, United States
| | - Paul R Selvin
- Department of Physics, Biophysics, and the Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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23
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Helassa N, Dürst CD, Coates C, Kerruth S, Arif U, Schulze C, Wiegert JS, Geeves M, Oertner TG, Török K. Ultrafast glutamate sensors resolve high-frequency release at Schaffer collateral synapses. Proc Natl Acad Sci U S A 2018; 115:5594-5599. [PMID: 29735711 PMCID: PMC6003469 DOI: 10.1073/pnas.1720648115] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Glutamatergic synapses display a rich repertoire of plasticity mechanisms on many different time scales, involving dynamic changes in the efficacy of transmitter release as well as changes in the number and function of postsynaptic glutamate receptors. The genetically encoded glutamate sensor iGluSnFR enables visualization of glutamate release from presynaptic terminals at frequencies up to ∼10 Hz. However, to resolve glutamate dynamics during high-frequency bursts, faster indicators are required. Here, we report the development of fast (iGlu f ) and ultrafast (iGlu u ) variants with comparable brightness but increased Kd for glutamate (137 μM and 600 μM, respectively). Compared with iGluSnFR, iGlu u has a sixfold faster dissociation rate in vitro and fivefold faster kinetics in synapses. Fitting a three-state model to kinetic data, we identify the large conformational change after glutamate binding as the rate-limiting step. In rat hippocampal slice culture stimulated at 100 Hz, we find that iGlu u is sufficiently fast to resolve individual glutamate release events, revealing that glutamate is rapidly cleared from the synaptic cleft. Depression of iGlu u responses during 100-Hz trains correlates with depression of postsynaptic EPSPs, indicating that depression during high-frequency stimulation is purely presynaptic in origin. At individual boutons, the recovery from depression could be predicted from the amount of glutamate released on the second pulse (paired pulse facilitation/depression), demonstrating differential frequency-dependent filtering of spike trains at Schaffer collateral boutons.
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Affiliation(s)
- Nordine Helassa
- Molecular and Clinical Sciences Research Institute, St George's, University of London, SW17 0RE London, United Kingdom
| | - Céline D Dürst
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, 20251 Hamburg, Germany
| | - Catherine Coates
- Molecular and Clinical Sciences Research Institute, St George's, University of London, SW17 0RE London, United Kingdom
| | - Silke Kerruth
- Molecular and Clinical Sciences Research Institute, St George's, University of London, SW17 0RE London, United Kingdom
| | - Urwa Arif
- Molecular and Clinical Sciences Research Institute, St George's, University of London, SW17 0RE London, United Kingdom
| | - Christian Schulze
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, 20251 Hamburg, Germany
| | - J Simon Wiegert
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, 20251 Hamburg, Germany
| | - Michael Geeves
- School of Biosciences, University of Kent, CT2 7NZ Canterbury, United Kingdom
| | - Thomas G Oertner
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, 20251 Hamburg, Germany
| | - Katalin Török
- Molecular and Clinical Sciences Research Institute, St George's, University of London, SW17 0RE London, United Kingdom;
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24
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Heller JP, Rusakov DA. The Nanoworld of the Tripartite Synapse: Insights from Super-Resolution Microscopy. Front Cell Neurosci 2017; 11:374. [PMID: 29225567 PMCID: PMC5705901 DOI: 10.3389/fncel.2017.00374] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 11/10/2017] [Indexed: 12/17/2022] Open
Abstract
Synaptic connections between individual nerve cells are fundamental to the process of information transfer and storage in the brain. Over the past decades a third key partner of the synaptic machinery has been unveiled: ultrathin processes of electrically passive astroglia which often surround pre- and postsynaptic structures. The recent advent of super-resolution (SR) microscopy has begun to uncover the dynamic nanoworld of synapses and their astroglial environment. Here we overview and discuss the current progress in our understanding of the synaptic nanoenvironment, as gleaned from the imaging methods that go beyond the diffraction limit of conventional light microscopy. We argue that such methods are essential to achieve a new level of comprehension pertinent to the principles of signal integration in the brain.
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Affiliation(s)
- Janosch P Heller
- UCL Institute of Neurology, University College London, London, United Kingdom
| | - Dmitri A Rusakov
- UCL Institute of Neurology, University College London, London, United Kingdom.,Institute of Neuroscience, University of Nizhny Novgorod, Nizhny Novgorod, Russia
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25
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Bannai H. Molecular membrane dynamics: Insights into synaptic function and neuropathological disease. Neurosci Res 2017; 129:47-56. [PMID: 28826905 DOI: 10.1016/j.neures.2017.07.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 07/14/2017] [Accepted: 07/26/2017] [Indexed: 11/19/2022]
Abstract
The fluid mosaic model states that molecules in the plasma membrane can freely undergo lateral diffusion; however, in neurons and glia, specific membrane molecules are concentrated in cellular microdomains to overcome the randomizing effects of free diffusion. This specialized distribution of membrane molecules is crucial for various cell functions; one example is the accumulation of neurotransmitter receptors at the postsynaptic neuronal membrane, which enables efficient synaptic transmission. Quantum dot-single particle tracking (QD-SPT) is a super-resolution imaging technique that uses semiconductor nanocrystal quantum dots as fluorescent probes, and is a powerful tool for analyzing protein and lipid behavior in the plasma membrane. In this article, we review studies implementing QD-SPT in neuroscience research and important data gleaned using this technology. Recent QD-SPT experiments have provided critical insights into the mechanism and physiological relevance of membrane self-organization in neurons and astrocytes in the brain. The mobility of some membrane molecules may become abnormal in cellular models of epilepsy and Alzheimer's disease. Based on these findings, we propose that the behavior of membrane molecules reflects the condition of neurons in pathological disease states.
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Affiliation(s)
- Hiroko Bannai
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute (BSI), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
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Witkin JM, Li J, Gilmour G, Mitchell SN, Carter G, Gleason SD, Seidel WF, Eastwood BJ, McCarthy A, Porter WJ, Reel J, Gardinier KM, Kato AS, Wafford KA. Electroencephalographic, cognitive, and neurochemical effects of LY3130481 (CERC-611), a selective antagonist of TARP-γ8-associated AMPA receptors. Neuropharmacology 2017; 126:257-270. [PMID: 28757050 DOI: 10.1016/j.neuropharm.2017.07.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/27/2017] [Accepted: 07/26/2017] [Indexed: 11/18/2022]
Abstract
6-[(1S)-1-[1-[5-(2-hydroxyethoxy)-2-pyridyl]pyrazol-3-yl]ethyl]-3H-1,3-benzothiazol-2-one (LY3130481 or CERC-611) is a selective antagonist of AMPA receptors containing transmembrane AMPA receptor regulatory protein (TARP) γ-8. This molecule has been characterized as a potent and efficacious anticonvulsant in an array of acute and chronic epilepsy models in rodents. The present set of experiments was designed to assess the effects of LY3130481 on the electroencephelogram (EEG), cognitive function, and neurochemical outflow. LY3130481 disrupted food-maintained responding in rats and spontaneous alternation in a Y-maze in mice. In rat fear conditioning, LY3130481 caused a deficit in trace (hippocampal-dependent), but not in delay fear conditioning. Although these effects on cognitive performances were observed, the known cognitive-impairing anticonvulsant, topiramate, did not always produce deficits under these assay conditions. LY3130481 produced modest increases in wake times in rats. In addition, LY3130481 was able to attenuate some impairing effects of standard antiepileptic drugs. The motor-impairing effects of the lacosamide were attenuated by LY3130481 as was the decrease in non-rapid-eye movement sleep induced by carbamazepine. Evaluation of the effect of LY3130481 on neurotransmitter and metabolite efflux in the rat medial prefrontal cortex, using in vivo microdialysis, revealed significant increases in the pro-cognitive and wake-promoting neurotransmitters, histamine and acetylcholine, as well as in serotonin, telemethylhistamine, 5-HIAA, HVA and MHPG. LY3130481 thus presents a novel behavioral profile that will have to be evaluated in patients to fully appreciate its implications for therapeutics. LY3130481 is currently under clinical development as CERC-611 as an antiepileptic.
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Affiliation(s)
- Jeffrey M Witkin
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA.
| | - Jennifer Li
- Lilly Research Laboratories, Eli Lilly and Company, Windlesham, Surrey, UK
| | - Gary Gilmour
- Lilly Research Laboratories, Eli Lilly and Company, Windlesham, Surrey, UK
| | - Stephen N Mitchell
- Lilly Research Laboratories, Eli Lilly and Company, Windlesham, Surrey, UK
| | - Guy Carter
- Lilly Research Laboratories, Eli Lilly and Company, Windlesham, Surrey, UK
| | - Scott D Gleason
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA
| | - Wesley F Seidel
- Lilly Research Laboratories, Eli Lilly and Company, Windlesham, Surrey, UK
| | - Brian J Eastwood
- Lilly Research Laboratories, Eli Lilly and Company, Windlesham, Surrey, UK
| | - Andrew McCarthy
- Lilly Research Laboratories, Eli Lilly and Company, Windlesham, Surrey, UK
| | - Warren J Porter
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA
| | - Jon Reel
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA
| | - Kevin M Gardinier
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA
| | - Akihiko S Kato
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA
| | - Keith A Wafford
- Lilly Research Laboratories, Eli Lilly and Company, Windlesham, Surrey, UK.
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