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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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Cornelius J, Haak S, Rothkegel M, Korte M, Michaelsen-Preusse K. Phosphorylation of the actin-binding protein profilin2a at S137 modulates bidirectional structural plasticity at dendritic spines. Front Cell Dev Biol 2023; 11:1107380. [PMID: 36875774 PMCID: PMC9975505 DOI: 10.3389/fcell.2023.1107380] [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: 11/24/2022] [Accepted: 02/06/2023] [Indexed: 02/17/2023] Open
Abstract
Background: Synaptic plasticity requires constant adaptation of functional and structural features at individual synaptic connections. Rapid re-modulation of the synaptic actin cytoskeleton provides the scaffold orchestrating both morphological and functional modifications. A major regulator of actin polymerization not only in neurons but also in various other cell types is the actin-binding protein profilin. While profilin is known to mediate the ADP to ATP exchange at actin monomers through its direct interaction with G-actin, it additionally is able to influence actin dynamics by binding to membrane-bound phospholipids as phosphatidylinositol (4,5)-bisphosphate (PIP2) as well as several other proteins containing poly-L-proline motifs including actin modulators like Ena/VASP, WAVE/WASP or formins. Notably, these interactions are proposed to be mediated by a fine-tuned regulation of post-translational phosphorylation of profilin. However, while phosphorylation sites of the ubiquitously expressed isoform profilin1 have been described and analyzed previously, there is still only little known about the phosphorylation of the profilin2a isoform predominantly expressed in neurons. Methods: Here, utilizing a knock-down/knock-in approach, we replaced endogenously expressed profilin2a by (de)phospho-mutants of S137 known to alter actin-, PIP2 and PLP-binding properties of profilin2a and analyzed their effect on general actin dynamics as well as activity-dependent structural plasticity. Results and Discussion: Our findings suggest that a precisely timed regulation of profilin2a phosphorylation at S137 is needed to mediate actin dynamics and structural plasticity bidirectionally during long-term potentiation and long-term depression, respectively.
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Affiliation(s)
- Jonas Cornelius
- Division of Cellular Neurobiology, Zoological Institute, TU Braunschweig, Braunschweig, Germany
| | - Stefan Haak
- Division of Cellular Neurobiology, Zoological Institute, TU Braunschweig, Braunschweig, Germany
| | - Martin Rothkegel
- Division of Cellular Neurobiology, Zoological Institute, TU Braunschweig, Braunschweig, Germany
| | - Martin Korte
- Division of Cellular Neurobiology, Zoological Institute, TU Braunschweig, Braunschweig, Germany.,Helmholtz Centre for Infection Research, Research group Neuroinflammation and Neurodegeneration, Braunschweig, Germany
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3
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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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4
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Grothe T, Nowak J, Jahn R, Walla PJ. Selected tools to visualize membrane interactions. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:211-222. [PMID: 33787948 PMCID: PMC8071796 DOI: 10.1007/s00249-021-01516-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 02/19/2021] [Accepted: 03/08/2021] [Indexed: 11/28/2022]
Abstract
In the past decade, we developed various fluorescence-based methods for monitoring membrane fusion, membrane docking, distances between membranes, and membrane curvature. These tools were mainly developed using liposomes as model systems, which allows for the dissection of specific interactions mediated by, for example, fusion proteins. Here, we provide an overview of these methods, including two-photon fluorescence cross-correlation spectroscopy and intramembrane Förster energy transfer, with asymmetric labelling of inner and outer membrane leaflets and the calibrated use of transmembrane energy transfer to determine membrane distances below 10 nm. We discuss their application range and their limitations using examples from our work on protein-mediated vesicle docking and fusion.
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Affiliation(s)
- Tobias Grothe
- Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, 37077, Göttingen, Germany
- Department of Biophysical Chemistry, Institute for Physical and Theoretical Chemistry, University of Braunschweig, 38106, Braunschweig, Germany
| | - Julia Nowak
- Department of Biophysical Chemistry, Institute for Physical and Theoretical Chemistry, University of Braunschweig, 38106, Braunschweig, Germany
| | - Reinhard Jahn
- Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, 37077, Göttingen, Germany
| | - Peter Jomo Walla
- Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, 37077, Göttingen, Germany.
- Department of Biophysical Chemistry, Institute for Physical and Theoretical Chemistry, University of Braunschweig, 38106, Braunschweig, Germany.
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5
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Wu L, Wang Q, Gu J, Zhang H, Gu Y. Modulation of Actin Filament Dynamics by Inward Rectifying of Potassium Channel Kir2.1. Int J Mol Sci 2020; 21:ijms21207479. [PMID: 33050503 PMCID: PMC7589188 DOI: 10.3390/ijms21207479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/02/2020] [Accepted: 10/06/2020] [Indexed: 01/17/2023] Open
Abstract
Apart from its ion channel properties, the Kir2.1 channel has been found in tumors and cancer cells to facilitate cancer cell motility. It is assumed that Kir2.1 might be associated with cell actin filament dynamics. With the help of structured illumination microscopy (SIM), we show that Kir2.1 overexpression promotes actin filament dynamics, cell invasion, and adhesion. Mutated Kir2.1 channels, with impaired membrane expression, present much weaker actin regulatory effects, which indicates that precise Kir2.1 membrane localization is key to its actin filament remolding effect. It is found that Kir2.1 membrane expression and anchoring are associated with PIP2 affinity, and PIP2 depletion inhibits actin filament dynamics. We also report that membrane-expressed Kir2.1 regulates redistribution and phosphorylation of FLNA (filamin A), which may be the mechanism underlying Kir2.1 and actin filament dynamics. In conclusion, Kir2.1 membrane localization regulates cell actin filaments, and not the ion channel properties. These data indicate that Kir2.1 may have additional cellular functions distinct from the regulation of excitability, which provides new insight into the study of channel proteins.
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Affiliation(s)
- Lida Wu
- Molecular Pharmacology Laboratory, Institute of Molecular Medicine, Peking University, Beijing 100871, China; (L.W.); (J.G.); (H.Z.)
- Aston Medical School, Aston University, Birmingham B4 7ET, UK
| | - Quanyi Wang
- Department of Biopharmaceutics, School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China;
| | - Junzhong Gu
- Molecular Pharmacology Laboratory, Institute of Molecular Medicine, Peking University, Beijing 100871, China; (L.W.); (J.G.); (H.Z.)
| | - Huiyuan Zhang
- Molecular Pharmacology Laboratory, Institute of Molecular Medicine, Peking University, Beijing 100871, China; (L.W.); (J.G.); (H.Z.)
| | - Yuchun Gu
- Molecular Pharmacology Laboratory, Institute of Molecular Medicine, Peking University, Beijing 100871, China; (L.W.); (J.G.); (H.Z.)
- Aston Medical School, Aston University, Birmingham B4 7ET, UK
- Correspondence:
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6
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Fujita H, Oikawa R, Hayakawa M, Tomoike F, Kimura Y, Okuno H, Hatashita Y, Fiallos Oliveros C, Bito H, Ohshima T, Tsuneda S, Abe H, Inoue T. Quantification of native mRNA dynamics in living neurons using fluorescence correlation spectroscopy and reduction-triggered fluorescent probes. J Biol Chem 2020; 295:7923-7940. [PMID: 32341124 PMCID: PMC7278347 DOI: 10.1074/jbc.ra119.010921] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 04/22/2020] [Indexed: 11/06/2022] Open
Abstract
RNA localization in subcellular compartments is essential for spatial and temporal regulation of protein expression in neurons. Several techniques have been developed to visualize mRNAs inside cells, but the study of the behavior of endogenous and nonengineered mRNAs in living neurons has just started. In this study, we combined reduction-triggered fluorescent (RETF) probes and fluorescence correlation spectroscopy (FCS) to investigate the diffusion properties of activity-regulated cytoskeleton-associated protein (Arc) and inositol 1,4,5-trisphosphate receptor type 1 (Ip3r1) mRNAs. This approach enabled us to discriminate between RNA-bound and unbound fluorescent probes and to quantify mRNA diffusion parameters and concentrations in living rat primary hippocampal neurons. Specifically, we detected the induction of Arc mRNA production after neuronal activation in real time. Results from computer simulations with mRNA diffusion coefficients obtained in these analyses supported the idea that free diffusion is incapable of transporting mRNA of sizes close to those of Arc or Ip3r1 to distal dendrites. In conclusion, the combined RETF-FCS approach reported here enables analyses of the dynamics of endogenous, unmodified mRNAs in living neurons, affording a glimpse into the intracellular dynamics of RNA in live cells.
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Affiliation(s)
- Hirotaka Fujita
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Ryota Oikawa
- Department of Chemistry, Graduate School of Science, Nagoya University, Aichi, Japan
| | - Mayu Hayakawa
- Department of Chemistry, Graduate School of Science, Nagoya University, Aichi, Japan
| | - Fumiaki Tomoike
- Department of Chemistry, Graduate School of Science, Nagoya University, Aichi, Japan
| | - Yasuaki Kimura
- Department of Chemistry, Graduate School of Science, Nagoya University, Aichi, Japan
| | - Hiroyuki Okuno
- Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Yoshiki Hatashita
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Carolina Fiallos Oliveros
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Haruhiko Bito
- Department of Neurochemistry, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Toshio Ohshima
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Satoshi Tsuneda
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Hiroshi Abe
- Department of Chemistry, Graduate School of Science, Nagoya University, Aichi, Japan
| | - Takafumi Inoue
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
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7
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Roesler MK, Lombino FL, Freitag S, Schweizer M, Hermans-Borgmeyer I, Schwarz JR, Kneussel M, Wagner W. Myosin XVI Regulates Actin Cytoskeleton Dynamics in Dendritic Spines of Purkinje Cells and Affects Presynaptic Organization. Front Cell Neurosci 2019; 13:330. [PMID: 31474830 PMCID: PMC6705222 DOI: 10.3389/fncel.2019.00330] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 07/04/2019] [Indexed: 11/29/2022] Open
Abstract
The actin cytoskeleton is crucial for function and morphology of neuronal synapses. Moreover, altered regulation of the neuronal actin cytoskeleton has been implicated in neuropsychiatric diseases such as autism spectrum disorder (ASD). Myosin XVI is a neuronally expressed unconventional myosin known to bind the WAVE regulatory complex (WRC), a regulator of filamentous actin (F-actin) polymerization. Notably, the gene encoding the myosin’s heavy chain (MYO16) shows genetic association with neuropsychiatric disorders including ASD. Here, we investigated whether myosin XVI plays a role for actin cytoskeleton regulation in the dendritic spines of cerebellar Purkinje cells (PCs), a neuronal cell type crucial for motor learning, social cognition and vocalization. We provide evidence that both myosin XVI and the WRC component WAVE1 localize to PC spines. Fluorescence recovery after photobleaching (FRAP) analysis of GFP-actin in cultured PCs shows that Myo16 knockout as well as PC-specific Myo16 knockdown, lead to faster F-actin turnover in the dendritic spines of PCs. We also detect accelerated F-actin turnover upon interference with the WRC, and upon inhibition of Arp2/3 that drives formation of branched F-actin downstream of the WRC. In contrast, inhibition of formins that are responsible for polymerization of linear actin filaments does not cause faster F-actin turnover. Together, our data establish myosin XVI as a regulator of the postsynaptic actin cytoskeleton and suggest that it is an upstream activator of the WRC-Arp2/3 pathway in PC spines. Furthermore, ultra-structural and electrophysiological analyses of Myo16 knockout cerebellum reveals the presence of reduced numbers of synaptic vesicles at presynaptic terminals in the absence of the myosin. Therefore, we here define myosin XVI as an F-actin regulator important for presynaptic organization in the cerebellum.
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Affiliation(s)
- Mona Katrin Roesler
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Franco Luis Lombino
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sandra Freitag
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Michaela Schweizer
- Electron Microscopy Unit, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Irm Hermans-Borgmeyer
- Transgenic Animal Unit, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jürgen R Schwarz
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Matthias Kneussel
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Wolfgang Wagner
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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8
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Obashi K, Matsuda A, Inoue Y, Okabe S. Precise Temporal Regulation of Molecular Diffusion within Dendritic Spines by Actin Polymers during Structural Plasticity. Cell Rep 2019; 27:1503-1515.e8. [DOI: 10.1016/j.celrep.2019.04.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 02/22/2019] [Accepted: 03/29/2019] [Indexed: 10/26/2022] Open
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9
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Iobbi C, Korte M, Zagrebelsky M. Nogo-66 Restricts Synaptic Strengthening via Lingo1 and the ROCK2-Cofilin Pathway to Control Actin Dynamics. Cereb Cortex 2018; 27:2779-2792. [PMID: 27166169 DOI: 10.1093/cercor/bhw122] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Nogo-A restricts long-term potentiation (LTP) at the Schaffer collateral-CA1 pathway in the adult hippocampus via 2 extracellular domains: Nogo-A-Δ20 and Nogo-66. Nogo-66 signals via Nogo Receptor 1 (NgR1) to regulate synaptic function. Whether the NgR1 coreceptors Lingo1 and p75NTR are involved in the signaling in this context is still not known. Moreover, the intracellular cascade mediating the activity of Nogo-66 in restricting LTP is unexplored. We combine electrophysiology and biochemistry in acute hippocampal slices and demonstrate that a loss of function for Lingo1 results in a significant increase in LTP levels at the Schaffer collateral-CA1 pathway, and that Lingo1 is the NgR1 coreceptor mediating the role of Nogo-66 in restricting LTP. Our data show that p75NTR is not involved in mediating the Nogo-66 effect on LTP. Moreover, loss of function for p75NTR and NgR1 equally attenuate LTD, suggesting that p75NTR might mediate the NgR1-dependent regulation of LTD, independently of Nogo-66. Finally, our results indicate that Nogo-66 signaling limits LTP via the ROCK2-Cofilin pathway to control the dynamics of the actin cytoskeleton. The present results elucidate the signaling pathway activated by Nogo-66 to control LTP and contribute to the understanding of how Nogo-A stabilizes the neural circuits to limit activity-dependent plasticity events in the mature hippocampus.
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Affiliation(s)
- Cristina Iobbi
- Zoological Institute, Division of Cellular Neurobiology, TU Braunschweig, 38106, Braunschweig, Germany
| | - Martin Korte
- Zoological Institute, Division of Cellular Neurobiology, TU Braunschweig, 38106, Braunschweig, Germany.,Helmholtz Centre for Infection Research, AG NIND, 38124, Braunschweig, Germany
| | - Marta Zagrebelsky
- Zoological Institute, Division of Cellular Neurobiology, TU Braunschweig, 38106, Braunschweig, Germany
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10
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Actin Tyrosine-53-Phosphorylation in Neuronal Maturation and Synaptic Plasticity. J Neurosci 2017; 36:5299-313. [PMID: 27170127 DOI: 10.1523/jneurosci.2649-15.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 03/31/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Rapid reorganization and stabilization of the actin cytoskeleton in dendritic spines enables cellular processes underlying learning, such as long-term potentiation (LTP). Dendritic spines are enriched in exceptionally short and dynamic actin filaments, but the studies so far have not revealed the molecular mechanisms underlying the high actin dynamics in dendritic spines. Here, we show that actin in dendritic spines is dynamically phosphorylated at tyrosine-53 (Y53) in rat hippocampal and cortical neurons. Our findings show that actin phosphorylation increases the turnover rate of actin filaments and promotes the short-term dynamics of dendritic spines. During neuronal maturation, actin phosphorylation peaks at the first weeks of morphogenesis, when dendritic spines form, and the amount of Y53-phosphorylated actin decreases when spines mature and stabilize. Induction of LTP transiently increases the amount of phosphorylated actin and LTP induction is deficient in neurons expressing mutant actin that mimics phosphorylation. Actin phosphorylation provides a molecular mechanism to maintain the high actin dynamics in dendritic spines during neuronal development and to induce fast reorganization of the actin cytoskeleton in synaptic plasticity. In turn, dephosphorylation of actin is required for the stabilization of actin filaments that is necessary for proper dendritic spine maturation and LTP maintenance. SIGNIFICANCE STATEMENT Dendritic spines are small protrusions from neuronal dendrites where the postsynaptic components of most excitatory synapses reside. Precise control of dendritic spine morphology and density is critical for normal brain function. Accordingly, aberrant spine morphology is linked to many neurological diseases. The actin cytoskeleton is a structural element underlying the proper morphology of dendritic spines. Therefore, defects in the regulation of the actin cytoskeleton in neurons have been implicated in neurological diseases. Here, we revealed a novel mechanism for regulating neuronal actin cytoskeleton that explains the specific organization and dynamics of actin in spines. The better we understand the regulation of the dendritic spine morphology, the better we understand what goes wrong in neurological diseases.
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11
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Regulation of the Postsynaptic Compartment of Excitatory Synapses by the Actin Cytoskeleton in Health and Its Disruption in Disease. Neural Plast 2016; 2016:2371970. [PMID: 27127658 PMCID: PMC4835652 DOI: 10.1155/2016/2371970] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 03/09/2016] [Indexed: 02/07/2023] Open
Abstract
Disruption of synaptic function at excitatory synapses is one of the earliest pathological changes seen in wide range of neurological diseases. The proper control of the segregation of neurotransmitter receptors at these synapses is directly correlated with the intact regulation of the postsynaptic cytoskeleton. In this review, we are discussing key factors that regulate the structure and dynamics of the actin cytoskeleton, the major cytoskeletal building block that supports the postsynaptic compartment. Special attention is given to the complex interplay of actin-associated proteins that are found in the synaptic specialization. We then discuss our current understanding of how disruption of these cytoskeletal elements may contribute to the pathological events observed in the nervous system under disease conditions with a particular focus on Alzheimer's disease pathology.
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12
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Hlushchenko I, Koskinen M, Hotulainen P. Dendritic spine actin dynamics in neuronal maturation and synaptic plasticity. Cytoskeleton (Hoboken) 2016; 73:435-41. [PMID: 26849484 DOI: 10.1002/cm.21280] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 01/27/2016] [Accepted: 01/27/2016] [Indexed: 11/09/2022]
Abstract
The majority of the postsynaptic terminals of excitatory synapses in the central nervous system exist on small bulbous structures on dendrites known as dendritic spines. The actin cytoskeleton is a structural element underlying the proper development and morphology of dendritic spines. Synaptic activity patterns rapidly change actin dynamics, leading to morphological changes in dendritic spines. In this mini-review, we will discuss recent findings on neuronal maturation and synaptic plasticity-induced changes in the dendritic spine actin cytoskeleton. We propose that actin dynamics in dendritic spines decrease through actin filament crosslinking during neuronal maturation. In long-term potentiation, we evaluate the model of fast breakdown of actin filaments through severing and rebuilding through polymerization and later stabilization through crosslinking. We will discuss the role of Ca(2+) in long-term depression, and suggest that actin filaments are dissolved through actin filament severing. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Iryna Hlushchenko
- Neuroscience Center, University of Helsinki, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Mikko Koskinen
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Pirta Hotulainen
- Neuroscience Center, University of Helsinki, Helsinki, Finland. .,Minerva Foundation Institute for Medical Research, Helsinki, Finland.
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