1
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Luu P, Fraser SE, Schneider F. More than double the fun with two-photon excitation microscopy. Commun Biol 2024; 7:364. [PMID: 38531976 DOI: 10.1038/s42003-024-06057-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 03/15/2024] [Indexed: 03/28/2024] Open
Abstract
For generations researchers have been observing the dynamic processes of life through the lens of a microscope. This has offered tremendous insights into biological phenomena that span multiple orders of time- and length-scales ranging from the pure magic of molecular reorganization at the membrane of immune cells, to cell migration and differentiation during development or wound healing. Standard fluorescence microscopy techniques offer glimpses at such processes in vitro, however, when applied in intact systems, they are challenged by reduced signal strengths and signal-to-noise ratios that result from deeper imaging. As a remedy, two-photon excitation (TPE) microscopy takes a special place, because it allows us to investigate processes in vivo, in their natural environment, even in a living animal. Here, we review the fundamental principles underlying TPE aimed at basic and advanced microscopy users interested in adopting TPE for intravital imaging. We focus on applications in neurobiology, present current trends towards faster, wider and deeper imaging, discuss the combination with photon counting technologies for metabolic imaging and spectroscopy, as well as highlight outstanding issues and drawbacks in development and application of these methodologies.
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Affiliation(s)
- Peter Luu
- Translational Imaging Center, Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, 90089, USA
- Department of Biological Sciences, Division of Molecular and Computational Biology, University of Southern California, Los Angeles, CA, 90089, USA
| | - Scott E Fraser
- Translational Imaging Center, Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, 90089, USA
- Department of Biological Sciences, Division of Molecular and Computational Biology, University of Southern California, Los Angeles, CA, 90089, USA
- Alfred Mann Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, 90089, USA
| | - Falk Schneider
- Translational Imaging Center, Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, 90089, USA.
- Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, CA, 90089, USA.
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2
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Karbowski J, Urban P. Information encoded in volumes and areas of dendritic spines is nearly maximal across mammalian brains. Sci Rep 2023; 13:22207. [PMID: 38097675 PMCID: PMC10721930 DOI: 10.1038/s41598-023-49321-9] [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: 09/05/2023] [Accepted: 12/06/2023] [Indexed: 12/17/2023] Open
Abstract
Many experiments suggest that long-term information associated with neuronal memory resides collectively in dendritic spines. However, spines can have a limited size due to metabolic and neuroanatomical constraints, which should effectively limit the amount of encoded information in excitatory synapses. This study investigates how much information can be stored in the population of sizes of dendritic spines, and whether it is optimal in any sense. It is shown here, using empirical data for several mammalian brains across different regions and physiological conditions, that dendritic spines nearly maximize entropy contained in their volumes and surface areas for a given mean size in cortical and hippocampal regions. Although both short- and heavy-tailed fitting distributions approach [Formula: see text] of maximal entropy in the majority of cases, the best maximization is obtained primarily for short-tailed gamma distribution. We find that most empirical ratios of standard deviation to mean for spine volumes and areas are in the range [Formula: see text], which is close to the theoretical optimal ratios coming from entropy maximization for gamma and lognormal distributions. On average, the highest entropy is contained in spine length ([Formula: see text] bits per spine), and the lowest in spine volume and area ([Formula: see text] bits), although the latter two are closer to optimality. In contrast, we find that entropy density (entropy per spine size) is always suboptimal. Our results suggest that spine sizes are almost as random as possible given the constraint on their size, and moreover the general principle of entropy maximization is applicable and potentially useful to information and memory storing in the population of cortical and hippocampal excitatory synapses, and to predicting their morphological properties.
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Affiliation(s)
- Jan Karbowski
- Institute of Applied Mathematics and Mechanics, University of Warsaw, Warsaw, Poland.
| | - Paulina Urban
- Laboratory of Functional and Structural Genomics, Centre of New Technologies, University of Warsaw, Warsaw, Poland
- College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Warsaw, Poland
- Laboratory of Databases and Business Analytics, National Information Processing Institute, National Research Institute, Warsaw, Poland
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3
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Kasai H, Ucar H, Morimoto Y, Eto F, Okazaki H. Mechanical transmission at spine synapses: Short-term potentiation and working memory. Curr Opin Neurobiol 2023; 80:102706. [PMID: 36931116 DOI: 10.1016/j.conb.2023.102706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 11/17/2022] [Accepted: 02/15/2023] [Indexed: 03/17/2023]
Abstract
Do dendritic spines, which comprise the postsynaptic component of most excitatory synapses, exist only for their structural dynamics, receptor trafficking, and chemical and electrical compartmentation? The answer is no. Simultaneous investigation of both spine and presynaptic terminals has recently revealed a novel feature of spine synapses. Spine enlargement pushes the presynaptic terminals with muscle-like force and augments the evoked glutamate release for up to 20 min. We now summarize the evidence that such mechanical transmission shares critical features in common with short-term potentiation (STP) and may represent the cellular basis of short-term and working memory. Thus, spine synapses produce the force of learning to leave structural traces for both short and long-term memories.
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Affiliation(s)
- Haruo Kasai
- International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo, Bunkyo-ku, Tokyo, Japan; Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
| | - Hasan Ucar
- International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo, Bunkyo-ku, Tokyo, Japan; Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Yuichi Morimoto
- International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo, Bunkyo-ku, Tokyo, Japan; Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Fumihiro Eto
- International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo, Bunkyo-ku, Tokyo, Japan; Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Hitoshi Okazaki
- International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo, Bunkyo-ku, Tokyo, Japan; Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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4
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KASAI H. Unraveling the mysteries of dendritic spine dynamics: Five key principles shaping memory and cognition. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2023; 99:254-305. [PMID: 37821392 PMCID: PMC10749395 DOI: 10.2183/pjab.99.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 07/11/2023] [Indexed: 10/13/2023]
Abstract
Recent research extends our understanding of brain processes beyond just action potentials and chemical transmissions within neural circuits, emphasizing the mechanical forces generated by excitatory synapses on dendritic spines to modulate presynaptic function. From in vivo and in vitro studies, we outline five central principles of synaptic mechanics in brain function: P1: Stability - Underpinning the integral relationship between the structure and function of the spine synapses. P2: Extrinsic dynamics - Highlighting synapse-selective structural plasticity which plays a crucial role in Hebbian associative learning, distinct from pathway-selective long-term potentiation (LTP) and depression (LTD). P3: Neuromodulation - Analyzing the role of G-protein-coupled receptors, particularly dopamine receptors, in time-sensitive modulation of associative learning frameworks such as Pavlovian classical conditioning and Thorndike's reinforcement learning (RL). P4: Instability - Addressing the intrinsic dynamics crucial to memory management during continual learning, spotlighting their role in "spine dysgenesis" associated with mental disorders. P5: Mechanics - Exploring how synaptic mechanics influence both sides of synapses to establish structural traces of short- and long-term memory, thereby aiding the integration of mental functions. We also delve into the historical background and foresee impending challenges.
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Affiliation(s)
- Haruo KASAI
- International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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5
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van Tartwijk FW, Kaminski CF. Protein Condensation, Cellular Organization, and Spatiotemporal Regulation of Cytoplasmic Properties. Adv Biol (Weinh) 2022; 6:e2101328. [PMID: 35796197 DOI: 10.1002/adbi.202101328] [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: 12/31/2021] [Revised: 05/15/2022] [Indexed: 01/28/2023]
Abstract
The cytoplasm is an aqueous, highly crowded solution of active macromolecules. Its properties influence the behavior of proteins, including their folding, motion, and interactions. In particular, proteins in the cytoplasm can interact to form phase-separated assemblies, so-called biomolecular condensates. The interplay between cytoplasmic properties and protein condensation is critical in a number of functional contexts and is the subject of this review. The authors first describe how cytoplasmic properties can affect protein behavior, in particular condensate formation, and then describe the functional implications of this interplay in three cellular contexts, which exemplify how protein self-organization can be adapted to support certain physiological phenotypes. The authors then describe the formation of RNA-protein condensates in highly polarized cells such as neurons, where condensates play a critical role in the regulation of local protein synthesis, and describe how different stressors trigger extensive reorganization of the cytoplasm, both through signaling pathways and through direct stress-induced changes in cytoplasmic properties. Finally, the authors describe changes in protein behavior and cytoplasmic properties that may occur in extremophiles, in particular organisms that have adapted to inhabit environments of extreme temperature, and discuss the implications and functional importance of these changes.
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Affiliation(s)
- Francesca W van Tartwijk
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, CB3 0AS, UK
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, CB3 0AS, UK
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6
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Autoregulation of switching behavior by cellular compartment size. Proc Natl Acad Sci U S A 2022; 119:e2116054119. [PMID: 35349334 PMCID: PMC9169097 DOI: 10.1073/pnas.2116054119] [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: 11/30/2022] Open
Abstract
Biochemical reactions often occur in small volumes within a cell, restricting the number of molecules to the hundreds or even tens. At this scale, reactions are discrete and stochastic, making reliable signaling difficult. This paper shows that the transition between discrete, stochastic reactions and macroscopic reactions can be exploited to make a self-regulating switch. This constitutes a previously unidentified kind of reaction network that may be present in small structures, such as synapses. Many kinds of cellular compartments comprise decision-making mechanisms that control growth and shrinkage of the compartment in response to external signals. Key examples include synaptic plasticity mechanisms that regulate the size and strength of synapses in the nervous system. However, when synaptic compartments and postsynaptic densities are small, such mechanisms operate in a regime where chemical reactions are discrete and stochastic due to low copy numbers of the species involved. In this regime, fluctuations are large relative to mean concentrations, and inherent discreteness leads to breakdown of mass-action kinetics. Understanding how synapses and other small compartments achieve reliable switching in the low–copy number limit thus remains a key open problem. We propose a self-regulating signaling motif that exploits the breakdown of mass-action kinetics to generate a reliable size-regulated switch. We demonstrate this in simple two- and three-species chemical reaction systems and uncover a key role for inhibitory loops among species in generating switching behavior. This provides an elementary motif that could allow size-dependent regulation in more complex reaction pathways and may explain discrepant experimental results on well-studied biochemical pathways.
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7
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Control of Synapse Structure and Function by Actin and Its Regulators. Cells 2022; 11:cells11040603. [PMID: 35203254 PMCID: PMC8869895 DOI: 10.3390/cells11040603] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 01/30/2022] [Accepted: 02/06/2022] [Indexed: 02/07/2023] Open
Abstract
Neurons transmit and receive information at specialized junctions called synapses. Excitatory synapses form at the junction between a presynaptic axon terminal and a postsynaptic dendritic spine. Supporting the shape and function of these junctions is a complex network of actin filaments and its regulators. Advances in microscopic techniques have enabled studies of the organization of actin at synapses and its dynamic regulation. In addition to highlighting recent advances in the field, we will provide a brief historical perspective of the understanding of synaptic actin at the synapse. We will also highlight key neuronal functions regulated by actin, including organization of proteins in the pre- and post- synaptic compartments and endocytosis of ion channels. We review the evidence that synapses contain distinct actin pools that differ in their localization and dynamic behaviors and discuss key functions for these actin pools. Finally, whole exome sequencing of humans with neurodevelopmental and psychiatric disorders has identified synaptic actin regulators as key disease risk genes. We briefly summarize how genetic variants in these genes impact neurotransmission via their impact on synaptic actin.
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8
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Miningou Zobon NT, Jędrzejewska-Szmek J, Blackwell KT. Temporal pattern and synergy influence activity of ERK signaling pathways during L-LTP induction. eLife 2021; 10:e64644. [PMID: 34374340 PMCID: PMC8363267 DOI: 10.7554/elife.64644] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 08/03/2021] [Indexed: 01/21/2023] Open
Abstract
Long-lasting long-term potentiation (L-LTP) is a cellular mechanism of learning and memory storage. Studies have demonstrated a requirement for extracellular signal-regulated kinase (ERK) activation in L-LTP produced by a diversity of temporal stimulation patterns. Multiple signaling pathways converge to activate ERK, with different pathways being required for different stimulation patterns. To answer whether and how different temporal patterns select different signaling pathways for ERK activation, we developed a computational model of five signaling pathways (including two novel pathways) leading to ERK activation during L-LTP induction. We show that calcium and cAMP work synergistically to activate ERK and that stimuli given with large intertrial intervals activate more ERK than shorter intervals. Furthermore, these pathways contribute to different dynamics of ERK activation. These results suggest that signaling pathways with different temporal sensitivities facilitate ERK activation to diversity of temporal patterns.
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Affiliation(s)
| | - Joanna Jędrzejewska-Szmek
- Laboratory of Neuroinformatic, Nencki Institute of Experimental Biology of Polish Academy of SciencesWarsawPoland
| | - Kim T Blackwell
- Interdisciplinary Program in Neuroscience, Bioengineering Department, George Mason UniversityFairfaxUnited States
- Krasnow Institute for Advanced Study, George Mason UniversityFairfaxUnited States
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9
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Yang Y, Chen J, Chen X, Li D, He J, Wang S, Zhao S, Yang X, Deng S, Tong C, Wang D, Guo Z, Li D, Ma C, Liang X, Shi YS, Liu JJ. Endophilin A1 drives acute structural plasticity of dendritic spines in response to Ca2+/calmodulin. J Cell Biol 2021; 220:212102. [PMID: 33988695 PMCID: PMC8129810 DOI: 10.1083/jcb.202007172] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 01/29/2021] [Accepted: 03/03/2021] [Indexed: 01/05/2023] Open
Abstract
Induction of long-term potentiation (LTP) in excitatory neurons triggers a large transient increase in the volume of dendritic spines followed by decays to sustained size expansion, a process termed structural LTP (sLTP) that contributes to the cellular basis of learning and memory. Although mechanisms regulating the early and sustained phases of sLTP have been studied intensively, how the acute spine enlargement immediately after LTP stimulation is achieved remains elusive. Here, we report that endophilin A1 orchestrates membrane dynamics with actin polymerization to initiate spine enlargement in NMDAR-mediated LTP. Upon LTP induction, Ca2+/calmodulin enhances binding of endophilin A1 to both membrane and p140Cap, a cytoskeletal regulator. Consequently, endophilin A1 rapidly localizes to the plasma membrane and recruits p140Cap to promote local actin polymerization, leading to spine head expansion. Moreover, its molecular functions in activity-induced rapid spine growth are required for LTP and long-term memory. Thus, endophilin A1 serves as a calmodulin effector to drive acute structural plasticity necessary for learning and memory.
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Affiliation(s)
- Yanrui Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jiang Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing University, Nanjing, China
| | - Xue Chen
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Di Li
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jianfeng He
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Shen Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Shun Zhao
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoyu Yang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Shikun Deng
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Chunfang Tong
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Dou Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Zhenzhen Guo
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Dong Li
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Cong Ma
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Xin Liang
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yun S Shi
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing University, Nanjing, China
| | - Jia-Jia Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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10
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Obashi K, Taraska JW, Okabe S. The role of molecular diffusion within dendritic spines in synaptic function. J Gen Physiol 2021; 153:e202012814. [PMID: 33720306 PMCID: PMC7967910 DOI: 10.1085/jgp.202012814] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/16/2021] [Indexed: 12/21/2022] Open
Abstract
Spines are tiny nanoscale protrusions from dendrites of neurons. In the cortex and hippocampus, most of the excitatory postsynaptic sites reside in spines. The bulbous spine head is connected to the dendritic shaft by a thin membranous neck. Because the neck is narrow, spine heads are thought to function as biochemically independent signaling compartments. Thus, dynamic changes in the composition, distribution, mobility, conformations, and signaling properties of molecules contained within spines can account for much of the molecular basis of postsynaptic function and regulation. A major factor in controlling these changes is the diffusional properties of proteins within this small compartment. Advances in measurement techniques using fluorescence microscopy now make it possible to measure molecular diffusion within single dendritic spines directly. Here, we review the regulatory mechanisms of diffusion in spines by local intra-spine architecture and discuss their implications for neuronal signaling and synaptic plasticity.
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Affiliation(s)
- Kazuki Obashi
- Biochemistry and Biophysics Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Justin W. Taraska
- Biochemistry and Biophysics Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Shigeo Okabe
- Department of Cellular Neurobiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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11
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Imaging of spine synapses using super-resolution microscopy. Anat Sci Int 2021; 96:343-358. [PMID: 33459976 DOI: 10.1007/s12565-021-00603-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 01/04/2021] [Indexed: 12/17/2022]
Abstract
Neuronal circuits in the neocortex and hippocampus are essential for higher brain functions such as motor learning and spatial memory. In the mammalian forebrain, most excitatory synapses of pyramidal neurons are formed on spines, which are tiny protrusions extending from the dendritic shaft. The spine contains specialized molecular machinery that regulates synaptic transmission and plasticity. Spine size correlates with the efficacy of synaptic transmission, and spine morphology affects signal transduction at the post-synaptic compartment. Plasticity-related changes in the structural and molecular organization of spine synapses are thought to underlie the cellular basis of learning and memory. Recent advances in super-resolution microscopy have revealed the molecular mechanisms of the nanoscale synaptic structures regulating synaptic transmission and plasticity in living neurons, which are difficult to investigate using electron microscopy alone. In this review, we summarize recent advances in super-resolution imaging of spine synapses and discuss the implications of nanoscale structures in the regulation of synaptic function, learning, and memory.
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12
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Regulation of actin dynamics in dendritic spines: Nanostructure, molecular mobility, and signaling mechanisms. Mol Cell Neurosci 2020; 109:103564. [DOI: 10.1016/j.mcn.2020.103564] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/04/2020] [Indexed: 12/16/2022] Open
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13
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Ji ZS, Liu QL, Zhang JF, Yang YH, Li J, Zhang GW, Tan MH, Lin HS, Guo GQ. SUMOylation of spastin promotes the internalization of GluA1 and regulates dendritic spine morphology by targeting microtubule dynamics. Neurobiol Dis 2020; 146:105133. [PMID: 33049318 DOI: 10.1016/j.nbd.2020.105133] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/24/2020] [Accepted: 10/06/2020] [Indexed: 10/23/2022] Open
Abstract
Dendritic spines are specialized structures involved in neuronal processes on which excitatory synaptic contact occurs. The microtubule cytoskeleton is vital for maintaining spine morphology and mature synapses. Spastin is related to microtubule-severing proteases and is involved in synaptic bouton formation. However, it is not yet known if spastin can be modified by Small Ubiquitin-like Modifier (SUMO) or how this modification regulates dendritic spines. Spastin was shown to be SUMOylated at K427, and its deSUMOylation promoted microtubule stability. In addition, SUMOylation of spastin was shown to affect signalling pathways associated with long term synaptic depression. SUMOylated spastin promoted the development of dendrites and dendritic spines. Moreover, SUMOylated spastin regulated endocytosis and affected the transport of the AMPA receptor, GluA1. Our findings suggest that SUMOylation of spastin promotes GluA1 internalization and regulates dendritic spine morphology through targeting of microtubule dynamics.
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Affiliation(s)
- Zhi-Sheng Ji
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Qiu-Ling Liu
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Ji-Feng Zhang
- Department of Anatomy, Neuroscience Laboratory for Cognitive and Developmental Disorders, Medical College of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Yu-Hao Yang
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Jiong Li
- Department of Anatomy, Neuroscience Laboratory for Cognitive and Developmental Disorders, Medical College of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Guo-Wei Zhang
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China
| | - Ming-Hui Tan
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China.
| | - Hong-Sheng Lin
- Department of Orthopedics, The First Affiliated Hospital of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China.
| | - Guo-Qing Guo
- Department of Anatomy, Neuroscience Laboratory for Cognitive and Developmental Disorders, Medical College of Jinan University, No.601 West Huangpu Avenue, Tianhe, Guangzhou 510630, China.
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14
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Silent synapses dictate cocaine memory destabilization and reconsolidation. Nat Neurosci 2019; 23:32-46. [PMID: 31792465 PMCID: PMC6930359 DOI: 10.1038/s41593-019-0537-6] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Accepted: 10/10/2019] [Indexed: 02/04/2023]
Abstract
Cocaine-associated memories are persistent, but, upon retrieval, become temporarily destabilized and vulnerable to disruptions, followed by reconsolidation. To explore the synaptic underpinnings for these memory dynamics, we studied AMPA receptor (AMPAR)-silent excitatory synapses, which are generated in the nucleus accumbens by cocaine self-administration, and subsequently mature after prolonged withdrawal by recruiting AMPARs, echoing acquisition and consolidation of cocaine memories. We show that, upon memory retrieval after prolonged withdrawal, the matured silent synapses become AMPAR-silent again, followed by re-maturation ~6 hr later, defining the onset and termination of a destabilization window of cocaine memories. These synaptic dynamics are controlled by Rac1, with decreased and increased Rac1 activities opening and closing, respectively, the silent synapse-mediated destabilization window. Preventing silent synapse re-maturation within the destabilization window decreases cue-induced cocaine seeking. Thus, cocaine-generated silent synapses constitute a discrete synaptic ensemble dictating the dynamics of cocaine-associated memories and can be targeted for memory disruption.
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15
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Liu L, Li H, Labbe B, Wang Y, Mao S, Cao Y, Zhao M, Liu S, Yu H, Deng X. Involvement of CaMKII in regulating the release of diplotene-arrested mouse oocytes by pAkt1 (Ser473). Cell Cycle 2019; 18:2986-2997. [PMID: 31530151 PMCID: PMC6791694 DOI: 10.1080/15384101.2019.1666596] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/04/2019] [Accepted: 09/06/2019] [Indexed: 10/26/2022] Open
Abstract
Calcium (Ca2+)/calmodulin-dependent protein kinase II (CaMKII) had been reported to play a role in the process of fertilization. However, the role of CaMKII in the release of diplotene-arrested oocytes is poorly understood. In this study, we explored the potential effect of CaMKII on Akt1 and the relationship among CaMKII, Akt1 and phosphatidylinositol (3,4,5)-trisphosphate (PIP3) during the meiotic resumption of mouse oocytes. We found that inhibition of CaMKII aggravated diplotene arrest. We detected the expression and distribution of pCaMKII (Thr286), pAkt1 (Ser473), Cdc25B and pCdc2 (Tyr15) when oocytes were treated with KN-93, SH-6, LY294002 or PIP3, respectively. Our data showed that down-regulated CaMKII by KN-93 decreased the levels of pAkt1 (Ser473) and rearranged the distribution of pAkt1 (Ser473). Meanwhile, down-regulated pAkt1 (Ser473) by SH-6 also decreased the levels of pCaMKII (Thr286), Cdc25B and pCdc2 (Tyr15) significantly and rearranged the distributions of pCaMKII (Thr286). Furthermore, our data showed that exogenous PIP3 up-regulated GVBD rates significantly and increased the levels of pCaMKII (Thr286) and pAkt1 (Ser473). On the contrary, down-regulation of PIP3 by LY294002 decreased GVBD rates and the levels of pCaMKII (Thr286) and pAkt1 (Ser473), respectively. Our results showed that Akt1 and CaMKII regulated each other, and PIP3 may be involved in these regulations during the release of mouse oocytes from diplotene arrest.
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Affiliation(s)
- Lingling Liu
- Central Laboratory of the Fourth Affiliated Hospital, CMU, Shenyang, PR China
- Department of Physiology, China Medical University (CMU), Shenyang, PR China
- Mouse Genome Editing Core, Dept of Laboratory Animal Science, Shanghai Public Health Clincial Center, Fudan University, Shanghai, PR China
| | - Hanwen Li
- Department of Anorectum, the Fourth Affiliated Hospital, China Medical University (CMU), Shenyang, PR China
| | - Ben Labbe
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Yang Wang
- Department of Physiology, China Medical University (CMU), Shenyang, PR China
| | - Shitao Mao
- Department of Pneumology, the Fourth Affiliated Hospital, CMU, Shenyang, PR China
| | - Yu Cao
- Department of Physiology, China Medical University (CMU), Shenyang, PR China
| | - Mingjing Zhao
- Department of Pneumology, the Fourth Affiliated Hospital, CMU, Shenyang, PR China
| | - Shuo Liu
- Department of Pneumology, the Fourth Affiliated Hospital, CMU, Shenyang, PR China
| | - Hang Yu
- Department of Biophysics, China Medical University (CMU), Shenyang, China
| | - Xin Deng
- Central Laboratory of the Fourth Affiliated Hospital, CMU, Shenyang, PR China
- Department of Physiology, China Medical University (CMU), Shenyang, PR China
- Department of Pneumology, the Fourth Affiliated Hospital, CMU, Shenyang, PR China
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