51
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Zhang Y, Chopp M, Rex CS, Simmon VF, Sarraf ST, Zhang ZG, Mahmood A, Xiong Y. A Small Molecule Spinogenic Compound Enhances Functional Outcome and Dendritic Spine Plasticity in a Rat Model of Traumatic Brain Injury. J Neurotrauma 2018; 36:589-600. [PMID: 30014757 DOI: 10.1089/neu.2018.5790] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The tetra (ethylene glycol) derivative of benzothiazole aniline (SPG101) has been shown to improve dendritic spine density and cognitive memory in the triple transgenic mouse model of Alzheimer disease (AD) when administered intraperitoneally. The present study was designed to investigate the therapeutic effects of SPG101 on dendritic spine density and morphology and sensorimotor and cognitive functional recovery in a rat model of traumatic brain injury (TBI) induced by controlled cortical impact (CCI). Young adult male Wistar rats with CCI were randomly divided into the following two groups (n = 7/group): (1) Vehicle, and (2) SPG101. SPG101 (30 mg/kg) dissolved in vehicle (1% dimethyl sulfoxide in phosphate buffered saline) or Vehicle were intraperitoneally administered starting at 1 h post-injury and once daily for the next 34 days. Sensorimotor deficits were assessed using a modified neurological severity score and adhesive removal and foot fault tests. Cognitive function was measured by Morris water maze, novel object recognition (NOR), and three-chamber social recognition tests. The animals were sacrificed 35 days after injury, and their brains were processed for measurement of dendritic spine density and morphology using ballistic dye labeling. Compared with the vehicle treatment, SPG101 treatment initiated 1 h post-injury significantly improved sensorimotor functional recovery (days 7-35, p < 0.0001), spatial learning (days 32-35, p < 0.0001), NOR (days 14 and 35, p < 0.0001), social recognition (days 14 and 35, p < 0.0001). Further, treatment significantly increased dendritic spine density in the injured cortex (p < 0.05), decreased heterogeneous distribution of spine lengths in the injured cortex and hippocampus (p < 0.0001), modifications that are associated with the promotion of spine maturation in these brain regions. In summary, treatment with SPG101 initiated 1 h post-injury and continued for an additional 34 days improves both sensorimotor and cognitive functional recovery, indicating that SPG101 acts as a spinogenic agent and may have potential as a novel treatment of TBI.
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Affiliation(s)
- Yanlu Zhang
- 1 Department of Neurosurgery, Henry Ford Hospital , Detroit, Michigan
| | - Michael Chopp
- 2 Department of Neurology, Henry Ford Hospital , Detroit, Michigan.,3 Department of Physics, Oakland University , Rochester, Michigan
| | | | | | | | - Zheng Gang Zhang
- 2 Department of Neurology, Henry Ford Hospital , Detroit, Michigan
| | - Asim Mahmood
- 1 Department of Neurosurgery, Henry Ford Hospital , Detroit, Michigan
| | - Ye Xiong
- 1 Department of Neurosurgery, Henry Ford Hospital , Detroit, Michigan
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52
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Briggs SB, Hafenbreidel M, Young EJ, Rumbaugh G, Miller CA. The role of nonmuscle myosin II in polydrug memories and memory reconsolidation. ACTA ACUST UNITED AC 2018; 25:391-398. [PMID: 30115760 PMCID: PMC6097765 DOI: 10.1101/lm.046763.117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 06/21/2018] [Indexed: 12/13/2022]
Abstract
Using pharmacologic and genetic approaches targeting actin or the actin-driving molecular motor, nonmuscle myosin II (NMII), we previously discovered an immediate, retrieval-independent, and long-lasting disruption of methamphetamine- (METH-) and amphetamine-associated memories. A single intrabasolateral amygdala complex infusion or systemic administration of the NMII inhibitor Blebbistatin (Blebb) is sufficient to produce this disruption, which is selective, having no retrieval-independent effect on memories for fear, food reward, cocaine, or morphine. However, it was unclear if Blebb treatment would disrupt memories of other stimulants and amphetamine class drugs, such as nicotine (NIC) or mephedrone (MEPH; bath salts). Moreover, many individuals abuse multiple drugs, but it was unknown if Blebb could disrupt polydrug memories, or if the inclusion of another substance would render Blebb no longer able to disrupt METH-associated memories. Therefore, the present study had two primary goals: (1) to determine the ability of Blebb to disrupt NIC- or MEPH-associated memories, and (2) to determine the ability of METH to modify other unconditioned stimulus (US) associations’ susceptibility to Blebb. To this end, using the conditional place preference model, mice were conditioned to NIC and MEPH alone or METH in combination with NIC, morphine, or foot shock. We report that, unlike METH, there was no retrieval-independent effect of Blebb on NIC- or MEPH-associated memories. However, similar to cocaine, reconsolidation of the memory for both drugs was disrupted. Further, when combined with METH administration, NIC- and morphine-, but not fear-, associated memories were rendered susceptible to disruption by Blebb. Given the high rate of polydrug use and the resurgence of METH use, these results have important implications for the treatment of substance use disorder.
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Affiliation(s)
- Sherri B Briggs
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, Florida 33458, USA.,Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Madalyn Hafenbreidel
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, Florida 33458, USA.,Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Erica J Young
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, Florida 33458, USA.,Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Gavin Rumbaugh
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Courtney A Miller
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, Florida 33458, USA.,Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, USA
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53
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Dash B, Dib-Hajj SD, Waxman SG. Multiple myosin motors interact with sodium/potassium-ATPase alpha 1 subunits. Mol Brain 2018; 11:45. [PMID: 30086768 PMCID: PMC6081954 DOI: 10.1186/s13041-018-0388-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 07/20/2018] [Indexed: 11/10/2022] Open
Abstract
The alpha1 (α1) subunit of the sodium/potassium ATPase (i.e., Na+/K+-ATPase α1), the prototypical sodium pump, is expressed in each eukaryotic cell. They pump out three sodium ions in exchange for two extracellular potassium ions to establish a cellular electrochemical gradient important for firing of neuronal and cardiac action potentials. We hypothesized that myosin (myo or myh) motor proteins might interact with Na+/K+-ATPase α1 subunits in order for them to play an important role in the transport and trafficking of sodium pump. To this end immunoassays were performed to determine whether class II non-muscle myosins (i.e., NMHC-IIA/myh9, NMHC-IIB/myh10 or NMHC-IIC/myh14), myosin Va (myoVa) and myosin VI (myoVI) would interact with Na+/K+-ATPase α1 subunits. Immunoprecipitation of myh9, myh10, myh14, myoVa and myoVI from rat brain tissues led to the co-immunoprecipitation of Na+/K+-ATPase α1 subunits expressed there. Heterologous expression studies using HEK293 cells indicated that recombinant myh9, myh10, myh14 and myoVI interact with Na+/K+-ATPase α1 subunits expressed in HEK293 cells. Additional results indicated that loss of tail regions in recombinant myh9, myh10, myh14 and myoVI did not affect their interaction with Na+/K+-ATPase α1 subunits. However, recombinant myh9, myh10 and myh14 mutants having reduced or no actin binding ability, as a result of loss of their actin binding sites, displayed greatly reduced or null interaction with Na+/K+-ATPase α1 subunits. These results suggested the involvement of the actin binding site, but not tail regions, of NMHC-IIs in their interaction with Na+/K+-ATPase α1 subunits. Overall these results suggest a role for these diverse myosins in the trafficking and transport of sodium pump in neuronal and non-neuronal tissues.
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Affiliation(s)
- Bhagirathi Dash
- Department of Neurology, Yale University Schoolof Medicine, New Haven, CT, 06510, USA.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research center, VA Connecticut Healthcare System, 950 Campbell Avenue, Bldg. 34, West Haven, CT, 06516, USA
| | - Sulayman D Dib-Hajj
- Department of Neurology, Yale University Schoolof Medicine, New Haven, CT, 06510, USA.,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA.,Rehabilitation Research center, VA Connecticut Healthcare System, 950 Campbell Avenue, Bldg. 34, West Haven, CT, 06516, USA
| | - Stephen G Waxman
- Department of Neurology, Yale University Schoolof Medicine, New Haven, CT, 06510, USA. .,Center for Neuroscience & Regeneration Research, Yale University School of Medicine, New Haven, CT, 06510, USA. .,Rehabilitation Research center, VA Connecticut Healthcare System, 950 Campbell Avenue, Bldg. 34, West Haven, CT, 06516, USA.
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54
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Hlushchenko I, Khanal P, Abouelezz A, Paavilainen VO, Hotulainen P. ASD-Associated De Novo Mutations in Five Actin Regulators Show Both Shared and Distinct Defects in Dendritic Spines and Inhibitory Synapses in Cultured Hippocampal Neurons. Front Cell Neurosci 2018; 12:217. [PMID: 30123108 PMCID: PMC6085419 DOI: 10.3389/fncel.2018.00217] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 07/03/2018] [Indexed: 11/15/2022] Open
Abstract
Many actin cytoskeleton-regulating proteins control dendritic spine morphology and density, which are cellular features often altered in autism spectrum disorder (ASD). Recent studies using animal models show that autism-related behavior can be rescued by either manipulating actin regulators or by reversing dendritic spine density or morphology. Based on these studies, the actin cytoskeleton is a potential target pathway for developing new ASD treatments. Thus, it is important to understand how different ASD-associated actin regulators contribute to the regulation of dendritic spines and how ASD-associated mutations modulate this regulation. For this study, we selected five genes encoding different actin-regulating proteins and induced ASD-associated de novo missense mutations in these proteins. We assessed the functionality of the wild-type and mutated proteins by analyzing their subcellular localization, and by analyzing the dendritic spine phenotypes induced by the expression of these proteins. As the imbalance between excitation and inhibition has been suggested to have a central role in ASD, we additionally evaluated the density, size and subcellular localization of inhibitory synapses. Common for all the proteins studied was the enrichment in dendritic spines. ASD-associated mutations induced changes in the localization of α-actinin-4, which localized less to dendritic spines, and for SWAP-70 and SrGAP3, which localized more to dendritic spines. Among the wild-type proteins studied, only α-actinin-4 expression caused a significant change in dendritic spine morphology by increasing the mushroom spine density and decreasing thin spine density. We hypothesized that mutations associated with ASD shift dendritic spine morphology from mushroom to thin spines. An M554V mutation in α-actinin-4 (ACTN4) resulted in the expected shift in dendritic spine morphology by increasing the density of thin spines. In addition, we observed a trend toward higher thin spine density with mutations in myosin IXb and SWAP-70. Myosin IIb and myosin IXb expression increased the proportion of inhibitory synapses in spines. The expression of mutated myosin IIb (Y265C), SrGAP3 (E469K), and SWAP-70 (L544F) induced variable changes in inhibitory synapses.
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Affiliation(s)
- Iryna Hlushchenko
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Pushpa Khanal
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Amr Abouelezz
- Minerva Foundation Institute for Medical Research, Helsinki, Finland.,HiLIFE, University of Helsinki, Helsinki, Finland.,Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Ville O Paavilainen
- HiLIFE, University of Helsinki, Helsinki, Finland.,Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Pirta Hotulainen
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
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55
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Dash B, Han C, Waxman SG, Dib-Hajj SD. Nonmuscle myosin II isoforms interact with sodium channel alpha subunits. Mol Pain 2018; 14:1744806918788638. [PMID: 29956586 PMCID: PMC6052497 DOI: 10.1177/1744806918788638] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Sodium channels play pivotal roles in health and diseases due to their ability to control cellular excitability. The pore-forming α-subunits (sodium channel alpha subunits) of the voltage-sensitive channels (i.e., Nav1.1–1.9) and the nonvoltage-dependent channel (i.e., Nax) share a common structural motif and selectivity for sodium ions. We hypothesized that the actin-based nonmuscle myosin II motor proteins, nonmuscle myosin heavy chain-IIA/myh9, and nonmuscle myosin heavy chain-IIB/myh10 might interact with sodium channel alpha subunits to play an important role in their transport, trafficking, and/or function. Immunochemical and electrophysiological assays were conducted using rodent nervous (brain and dorsal root ganglia) tissues and ND7/23 cells coexpressing Nav subunits and recombinant myosins. Immunoprecipitation of myh9 and myh10 from rodent brain tissues led to the coimmunoprecipitation of Nax, Nav1.2, and Nav1.3 subunits, but not Nav1.1 and Nav1.6 subunits, expressed there. Similarly, immunoprecipitation of myh9 and myh10 from rodent dorsal root ganglia tissues led to the coimmunoprecipitation of Nav1.7 and Nav1.8 subunits, but not Nav1.9 subunits, expressed there. The functional implication of one of these interactions was assessed by coexpressing myh10 along with Nav1.8 subunits in ND7/23 cells. Myh10 overexpression led to three-fold increase (P < 0.01) in the current density of Nav1.8 channels expressed in ND7/23 cells. Myh10 coexpression also hyperpolarized voltage-dependent activation and steady-state fast inactivation of Nav1.8 channels. In addition, coexpression of myh10 reduced (P < 0.01) the offset of fast inactivation and the amplitude of the ramp currents of Nav1.8 channels. These results indicate that nonmuscle myosin heavy chain-IIs interact with sodium channel alpha subunits subunits in an isoform-dependent manner and influence their functional properties.
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Affiliation(s)
- Bhagirathi Dash
- 1 Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.,2 Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA.,3 Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Chongyang Han
- 1 Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.,2 Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA.,3 Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Stephen G Waxman
- 1 Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.,2 Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA.,3 Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Sulayman D Dib-Hajj
- 1 Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.,2 Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA.,3 Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT, USA
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56
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Dorn T, Kornherr J, Parrotta EI, Zawada D, Ayetey H, Santamaria G, Iop L, Mastantuono E, Sinnecker D, Goedel A, Dirschinger RJ, My I, Laue S, Bozoglu T, Baarlink C, Ziegler T, Graf E, Hinkel R, Cuda G, Kääb S, Grace AA, Grosse R, Kupatt C, Meitinger T, Smith AG, Laugwitz KL, Moretti A. Interplay of cell-cell contacts and RhoA/MRTF-A signaling regulates cardiomyocyte identity. EMBO J 2018; 37:e98133. [PMID: 29764980 PMCID: PMC6003642 DOI: 10.15252/embj.201798133] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 03/29/2018] [Accepted: 04/04/2018] [Indexed: 12/13/2022] Open
Abstract
Cell-cell and cell-matrix interactions guide organ development and homeostasis by controlling lineage specification and maintenance, but the underlying molecular principles are largely unknown. Here, we show that in human developing cardiomyocytes cell-cell contacts at the intercalated disk connect to remodeling of the actin cytoskeleton by regulating the RhoA-ROCK signaling to maintain an active MRTF/SRF transcriptional program essential for cardiomyocyte identity. Genetic perturbation of this mechanosensory pathway activates an ectopic fat gene program during cardiomyocyte differentiation, which ultimately primes the cells to switch to the brown/beige adipocyte lineage in response to adipogenesis-inducing signals. We also demonstrate by in vivo fate mapping and clonal analysis of cardiac progenitors that cardiac fat and a subset of cardiac muscle arise from a common precursor expressing Isl1 and Wt1 during heart development, suggesting related mechanisms of determination between the two lineages.
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Affiliation(s)
- Tatjana Dorn
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Jessica Kornherr
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Elvira I Parrotta
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- Department of Experimental and Clinical Medicine, Medical School, University of Magna Grecia, Catanzaro, Italy
| | - Dorota Zawada
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Harold Ayetey
- Wellcome Trust - Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
- Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Gianluca Santamaria
- Department of Experimental and Clinical Medicine, Medical School, University of Magna Grecia, Catanzaro, Italy
| | - Laura Iop
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Elisa Mastantuono
- Institute of Human Genetics, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Daniel Sinnecker
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
| | - Alexander Goedel
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
| | - Ralf J Dirschinger
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Ilaria My
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Svenja Laue
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Tarik Bozoglu
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | | | - Tilman Ziegler
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Elisabeth Graf
- Institute of Human Genetics, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Rabea Hinkel
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
- IPEK Institute for Cardiovascular Prevention, Klinikum der Universität München - Ludwig-Maximillians-Universität, Munich, Germany
| | - Giovanni Cuda
- Department of Experimental and Clinical Medicine, Medical School, University of Magna Grecia, Catanzaro, Italy
| | - Stefan Kääb
- Medizinische Klinik und Poliklinik I, Klinikum der Universität München - Ludwig-Maximillians-Universität, Munich, Germany
| | - Andrew A Grace
- Papworth Hospital NHS Foundation Trust, Cambridge, UK
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Robert Grosse
- Pharmacology Institute, Philipps University Marburg, Marburg, Germany
| | - Christian Kupatt
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
| | - Thomas Meitinger
- Institute of Human Genetics, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Austin G Smith
- Wellcome Trust - Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Karl-Ludwig Laugwitz
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
| | - Alessandra Moretti
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
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57
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Schätzle P, Esteves da Silva M, Tas RP, Katrukha EA, Hu HY, Wierenga CJ, Kapitein LC, Hoogenraad CC. Activity-Dependent Actin Remodeling at the Base of Dendritic Spines Promotes Microtubule Entry. Curr Biol 2018; 28:2081-2093.e6. [PMID: 29910073 DOI: 10.1016/j.cub.2018.05.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 03/17/2018] [Accepted: 05/02/2018] [Indexed: 10/14/2022]
Abstract
In neurons, microtubules form dense bundles and run along the length of axons and dendrites. Occasionally, dendritic microtubules can grow from the shaft directly into dendritic spines. Microtubules target dendritic spines that are undergoing activity-dependent changes, but the mechanism by which microtubules enter spines has remained poorly understood. Using live-cell imaging, high-resolution microscopy, and local glutamate uncaging, we show that local actin remodeling at the base of a spine promotes microtubule spine targeting. Microtubule spine entry is triggered by activation of N-Methyl-D-aspartic acid (NMDA) receptors and calcium influx and requires dynamic actin remodeling. Activity-dependent translocation of the actin remodeling protein cortactin out of the spine correlates with increased microtubule targeting at a single spine level. Our data show that the structural changes in the actin cytoskeleton at the base of the spine are directly involved in microtubule entry and emphasize the importance of actin-microtubule crosstalk in orchestrating synapse function and plasticity.
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Affiliation(s)
- Philipp Schätzle
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, the Netherlands
| | - Marta Esteves da Silva
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, the Netherlands
| | - Roderick P Tas
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, the Netherlands
| | - Eugene A Katrukha
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, the Netherlands
| | - Hai Yin Hu
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, the Netherlands
| | - Corette J Wierenga
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, the Netherlands
| | - Lukas C Kapitein
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, the Netherlands
| | - Casper C Hoogenraad
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, the Netherlands.
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58
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Joensuu M, Lanoue V, Hotulainen P. Dendritic spine actin cytoskeleton in autism spectrum disorder. Prog Neuropsychopharmacol Biol Psychiatry 2018; 84:362-381. [PMID: 28870634 DOI: 10.1016/j.pnpbp.2017.08.023] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 08/21/2017] [Accepted: 08/30/2017] [Indexed: 01/01/2023]
Abstract
Dendritic spines are small actin-rich protrusions from neuronal dendrites that form the postsynaptic part of most excitatory synapses. Changes in the shape and size of dendritic spines correlate with the functional changes in excitatory synapses and are heavily dependent on the remodeling of the underlying actin cytoskeleton. Recent evidence implicates synapses at dendritic spines as important substrates of pathogenesis in neuropsychiatric disorders, including autism spectrum disorder (ASD). Although synaptic perturbations are not the only alterations relevant for these diseases, understanding the molecular underpinnings of the spine and synapse pathology may provide insight into their etiologies and could reveal new drug targets. In this review, we will discuss recent findings of defective actin regulation in dendritic spines associated with ASD.
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Affiliation(s)
- Merja Joensuu
- Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland; Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Vanessa Lanoue
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Pirta Hotulainen
- Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland.
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59
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Koshida R, Tome S, Takei Y. Myosin Id localizes in dendritic spines through the tail homology 1 domain. Exp Cell Res 2018; 367:65-72. [PMID: 29559226 DOI: 10.1016/j.yexcr.2018.03.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 03/15/2018] [Accepted: 03/16/2018] [Indexed: 10/17/2022]
Abstract
Dendritic spines, the postsynaptic compartments at excitatory synapses, are capable of changing their shape and size to modulate synaptic transmission. The actin cytoskeleton and a variety of actin-binding proteins play a critical role in the dynamics of dendritic spines. Class I myosins are monomeric motor proteins that move along actin filaments using the energy of ATP hydrolysis. Of these class I myosins, myosin Id, the mammalian homolog of Drosophila Myo31DF, has been reported to be expressed in neurons, whereas its subcellular localization in neurons remained unknown. Here, we investigated the subcellular localization of myosin Id and determined the domain responsible for it. We found that myosin Id is enriched in the F-actin-rich pseudopodia of HEK293T cells and in the dendritic spines of primary hippocampal neurons. Both deletion and substitution of the tail homology 1 (TH1) domain drastically diminishes its colocalization with F-actin. In addition, the mutant form lacking the TH1 domain is less distributed in dendritic spines than is the full-length form. Taken together, our findings reveal that myosin Id localizes in dendritic spines through the TH1 domain.
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Affiliation(s)
- Ryusuke Koshida
- Department of Anatomy and Neuroscience, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8577, Japan.
| | - Saki Tome
- Department of Anatomy and Neuroscience, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8577, Japan
| | - Yosuke Takei
- Department of Anatomy and Neuroscience, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8577, Japan.
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60
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Zhang X, Li Q, Wang L, Liu ZJ, Zhong Y. Active Protection: Learning-Activated Raf/MAPK Activity Protects Labile Memory from Rac1-Independent Forgetting. Neuron 2018; 98:142-155.e4. [DOI: 10.1016/j.neuron.2018.02.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 12/20/2017] [Accepted: 02/23/2018] [Indexed: 12/20/2022]
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61
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Caverzasio S, Amato N, Manconi M, Prosperetti C, Kaelin-Lang A, Hutchison WD, Galati S. Brain plasticity and sleep: Implication for movement disorders. Neurosci Biobehav Rev 2018; 86:21-35. [DOI: 10.1016/j.neubiorev.2017.12.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 12/15/2017] [Accepted: 12/18/2017] [Indexed: 12/31/2022]
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62
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Ledda F, Paratcha G. Mechanisms regulating dendritic arbor patterning. Cell Mol Life Sci 2017; 74:4511-4537. [PMID: 28735442 PMCID: PMC11107629 DOI: 10.1007/s00018-017-2588-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 06/14/2017] [Accepted: 07/06/2017] [Indexed: 12/17/2022]
Abstract
The nervous system is populated by diverse types of neurons, each of which has dendritic trees with strikingly different morphologies. These neuron-specific morphologies determine how dendritic trees integrate thousands of synaptic inputs to generate different firing properties. To ensure proper neuronal function and connectivity, it is necessary that dendrite patterns are precisely controlled and coordinated with synaptic activity. Here, we summarize the molecular and cellular mechanisms that regulate the formation of cell type-specific dendrite patterns during development. We focus on different aspects of vertebrate dendrite patterning that are particularly important in determining the neuronal function; such as the shape, branching, orientation and size of the arbors as well as the development of dendritic spine protrusions that receive excitatory inputs and compartmentalize postsynaptic responses. Additionally, we briefly comment on the implications of aberrant dendritic morphology for nervous system disease.
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Affiliation(s)
- Fernanda Ledda
- Division of Molecular and Cellular Neuroscience, Institute of Cell Biology and Neuroscience (IBCN)-CONICET, School of Medicine, University of Buenos Aires (UBA), Paraguay 2155, 3rd Floor, CABA, 1121, Buenos Aires, Argentina
| | - Gustavo Paratcha
- Division of Molecular and Cellular Neuroscience, Institute of Cell Biology and Neuroscience (IBCN)-CONICET, School of Medicine, University of Buenos Aires (UBA), Paraguay 2155, 3rd Floor, CABA, 1121, Buenos Aires, Argentina.
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63
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Civiero L, Greggio E. PAKs in the brain: Function and dysfunction. Biochim Biophys Acta Mol Basis Dis 2017; 1864:444-453. [PMID: 29129728 DOI: 10.1016/j.bbadis.2017.11.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/31/2017] [Accepted: 11/06/2017] [Indexed: 12/17/2022]
Abstract
p21-Activated kinases (PAKs) comprise a family of proteins covering a central role in signal transduction. They are downstream effectors of Rho GTPases and can affect a variety of processes in different cell types and tissues by remodeling the cytoskeleton and by promoting gene transcription and cell survival. Given the relevance of cytoskeletal organization in neuronal development as well as synaptic function and the importance of pro-survival signals in controlling neuronal cell fate, accumulating studies investigated the role of PAKs in the nervous system. In this review, we provide a critical overview of the role of PAKs in the nervous system, both in neuronal and non-neuronal cells, and discuss their potential link with neurodegenerative diseases.
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64
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Romano DR, Pharris MC, Patel NM, Kinzer-Ursem TL. Competitive tuning: Competition's role in setting the frequency-dependence of Ca2+-dependent proteins. PLoS Comput Biol 2017; 13:e1005820. [PMID: 29107982 PMCID: PMC5690689 DOI: 10.1371/journal.pcbi.1005820] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 11/16/2017] [Accepted: 10/13/2017] [Indexed: 01/20/2023] Open
Abstract
A number of neurological disorders arise from perturbations in biochemical signaling and protein complex formation within neurons. Normally, proteins form networks that when activated produce persistent changes in a synapse’s molecular composition. In hippocampal neurons, calcium ion (Ca2+) flux through N-methyl-D-aspartate (NMDA) receptors activates Ca2+/calmodulin signal transduction networks that either increase or decrease the strength of the neuronal synapse, phenomena known as long-term potentiation (LTP) or long-term depression (LTD), respectively. The calcium-sensor calmodulin (CaM) acts as a common activator of the networks responsible for both LTP and LTD. This is possible, in part, because CaM binding proteins are “tuned” to different Ca2+ flux signals by their unique binding and activation dynamics. Computational modeling is used to describe the binding and activation dynamics of Ca2+/CaM signal transduction and can be used to guide focused experimental studies. Although CaM binds over 100 proteins, practical limitations cause many models to include only one or two CaM-activated proteins. In this work, we view Ca2+/CaM as a limiting resource in the signal transduction pathway owing to its low abundance relative to its binding partners. With this view, we investigate the effect of competitive binding on the dynamics of CaM binding partner activation. Using an explicit model of Ca2+, CaM, and seven highly-expressed hippocampal CaM binding proteins, we find that competition for CaM binding serves as a tuning mechanism: the presence of competitors shifts and sharpens the Ca2+ frequency-dependence of CaM binding proteins. Notably, we find that simulated competition may be sufficient to recreate the in vivo frequency dependence of the CaM-dependent phosphatase calcineurin. Additionally, competition alone (without feedback mechanisms or spatial parameters) could replicate counter-intuitive experimental observations of decreased activation of Ca2+/CaM-dependent protein kinase II in knockout models of neurogranin. We conclude that competitive tuning could be an important dynamic process underlying synaptic plasticity. Learning and memory formation are likely associated with dynamic fluctuations in the connective strength of neuronal synapses. These fluctuations, called synaptic plasticity, are regulated by calcium ion (Ca2+) influx through ion channels localized to the post-synaptic membrane. Within the post-synapse, the dominant Ca2+ sensor protein, calmodulin (CaM), may activate a variety of downstream binding partners, each contributing to synaptic plasticity outcomes. The conditions at which certain binding partners most strongly activate are increasingly studied using computational models. Nearly all computational studies describe these binding partners in combinations of only one or two CaM binding proteins. In contrast, we combine seven well-studied CaM binding partners into a single model wherein they simultaneously compete for access to CaM. Our dynamic model suggests that competition narrows the window of conditions for optimal activation of some binding partners, mimicking the Ca2+-frequency dependence of some proteins in vivo. Further characterization of CaM-dependent signaling dynamics in neuronal synapses may benefit our understanding of learning and memory formation. Furthermore, we propose that competitive binding may be another framework, alongside feedback and feed-forward loops, signaling motifs, and spatial localization, that can be applied to other signal transduction networks, particularly second messenger cascades, to explain the dynamical behavior of protein activation.
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Affiliation(s)
- Daniel R. Romano
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States of America
| | - Matthew C. Pharris
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States of America
| | - Neal M. Patel
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States of America
| | - Tamara L. Kinzer-Ursem
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States of America
- * E-mail:
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65
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The Brain-Enriched MicroRNA miR-9-3p Regulates Synaptic Plasticity and Memory. J Neurosci 2017; 36:8641-52. [PMID: 27535911 DOI: 10.1523/jneurosci.0630-16.2016] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 06/28/2016] [Indexed: 01/05/2023] Open
Abstract
UNLABELLED MicroRNAs (miRNAs) are small, noncoding RNAs that posttranscriptionally regulate gene expression in many tissues. Although a number of brain-enriched miRNAs have been identified, only a few specific miRNAs have been revealed as critical regulators of synaptic plasticity, learning, and memory. miR-9-5p/3p are brain-enriched miRNAs known to regulate development and their changes have been implicated in several neurological disorders, yet their role in mature neurons in mice is largely unknown. Here, we report that inhibition of miR-9-3p, but not miR-9-5p, impaired hippocampal long-term potentiation (LTP) without affecting basal synaptic transmission. Moreover, inhibition of miR-9-3p in the hippocampus resulted in learning and memory deficits. Furthermore, miR-9-3p inhibition increased the expression of the LTP-related genes Dmd and SAP97, the expression levels of which are negatively correlated with LTP. These results suggest that miR-9-3p-mediated gene regulation plays important roles in synaptic plasticity and hippocampus-dependent memory. SIGNIFICANCE STATEMENT Despite the abundant expression of the brain-specific microRNA miR-9-5p/3p in both proliferating and postmitotic neurons, most functional studies have focused on their role in neuronal development. Here, we examined the role of miR-9-5p/3p in adult brain and found that miR-9-3p, but not miR-9-5p, has a critical role in hippocampal synaptic plasticity and memory. Moreover, we identified in vivo binding targets of miR-9-3p that are involved in the regulation of long-term potentiation. Our study provides the very first evidence for the critical role of miR-9-3p in synaptic plasticity and memory in the adult mouse.
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66
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Mohamed RMP, Kumar J, Yap E, Mohamed IN, Sidi H, Adam RL, Das S. Try to Remember: Interplay between Memory and Substance Use Disorder. Curr Drug Targets 2017. [PMID: 28641520 DOI: 10.2174/1389450118666170622092824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Memories associated with substance use disorders, or substance-associated cues increase the likelihood of craving and relapse during abstinence. There is a growing consensus that manipulation of synaptic plasticity may reduce the strength of substance abuse-related memories. On the biological front, there are new insights that suggest memories associated with substance use disorder may follow unique neurobiological pathways that render them more accessible to pharmacological intervention. In parallel to this, research in neurochemistry has identified several potential candidate molecules that could influence the formation and maintenance of long-term memory. Drugs that target these molecules (blebbistatin, isradipine and zeta inhibitory peptide) have shown promise at the preclinical stage. In this review, we shall provide an overview of the evolving understanding on the biochemical mechanisms involved in memory formation and expound on the premise that substance use disorder is a learning disorder.
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Affiliation(s)
- Rashidi Mohamed Pakri Mohamed
- Department of Psychological Medicine, Faculty of Medicine, University of Malaya, Lembah Pantai, 59100 Kuala Lumpur, Malaysia
| | - Jaya Kumar
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, 56000 Cheras, Kuala Lumpur, Malaysia
| | - Ernie Yap
- Department of Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, 56000 Cheras, Kuala Lumpur, Malaysia
| | - Isa Naina Mohamed
- Department of Pharmacology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, 56000 Cheras, Kuala Lumpur, Malaysia
| | - Hatta Sidi
- Department of Psychiatry, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, 56000 Cheras, Kuala Lumpur, Malaysia
| | - Raja Lope Adam
- Department of Psychiatry, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, 56000 Cheras, Kuala Lumpur, Malaysia
| | - Srijit Das
- Department of Anatomy, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, 56000 Cheras, Kuala Lumpur, Malaysia
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67
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Konietzny A, Bär J, Mikhaylova M. Dendritic Actin Cytoskeleton: Structure, Functions, and Regulations. Front Cell Neurosci 2017; 11:147. [PMID: 28572759 PMCID: PMC5435805 DOI: 10.3389/fncel.2017.00147] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 05/05/2017] [Indexed: 12/28/2022] Open
Abstract
Actin is a versatile and ubiquitous cytoskeletal protein that plays a major role in both the establishment and the maintenance of neuronal polarity. For a long time, the most prominent roles that were attributed to actin in neurons were the movement of growth cones, polarized cargo sorting at the axon initial segment, and the dynamic plasticity of dendritic spines, since those compartments contain large accumulations of actin filaments (F-actin) that can be readily visualized using electron- and fluorescence microscopy. With the development of super-resolution microscopy in the past few years, previously unknown structures of the actin cytoskeleton have been uncovered: a periodic lattice consisting of actin and spectrin seems to pervade not only the whole axon, but also dendrites and even the necks of dendritic spines. Apart from that striking feature, patches of F-actin and deep actin filament bundles have been described along the lengths of neurites. So far, research has been focused on the specific roles of actin in the axon, while it is becoming more and more apparent that in the dendrite, actin is not only confined to dendritic spines, but serves many additional and important functions. In this review, we focus on recent developments regarding the role of actin in dendrite morphology, the regulation of actin dynamics by internal and external factors, and the role of F-actin in dendritic protein trafficking.
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Affiliation(s)
- Anja Konietzny
- DFG Emmy Noether Group 'Neuronal Protein Transport,' Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Julia Bär
- DFG Emmy Noether Group 'Neuronal Protein Transport,' Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-EppendorfHamburg, Germany
| | - Marina Mikhaylova
- DFG Emmy Noether Group 'Neuronal Protein Transport,' Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-EppendorfHamburg, Germany
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68
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Evans MD, Tufo C, Dumitrescu AS, Grubb MS. Myosin II activity is required for structural plasticity at the axon initial segment. Eur J Neurosci 2017; 46:1751-1757. [PMID: 28452088 PMCID: PMC5573965 DOI: 10.1111/ejn.13597] [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: 01/19/2017] [Revised: 03/29/2017] [Accepted: 04/20/2017] [Indexed: 12/21/2022]
Abstract
In neurons, axons possess a molecularly defined and highly organised proximal region – the axon initial segment (AIS) – that is a key regulator of both electrical excitability and cellular polarity. Despite existing as a large, dense structure with specialised cytoskeletal architecture, the AIS is surprisingly plastic, with sustained alterations in neuronal activity bringing about significant alterations to its position, length or molecular composition. However, although the upstream activity‐dependent signalling pathways that lead to such plasticity have begun to be elucidated, the downstream mechanisms that produce structural changes at the AIS are completely unknown. Here, we use dissociated cultures of rat hippocampus to show that two forms of AIS plasticity in dentate granule cells – long‐term relocation, and more rapid shortening – are completely blocked by treatment with blebbistatin, a potent and selective myosin II ATPase inhibitor. These data establish a link between myosin II and AIS function, and suggest that myosin II's primary role at the structure may be to effect activity‐dependent morphological alterations.
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Affiliation(s)
- Mark D Evans
- Centre for Developmental Neurobiology, King's College London, London, SE1 1UL, UK
| | - Candida Tufo
- Centre for Developmental Neurobiology, King's College London, London, SE1 1UL, UK
| | - Adna S Dumitrescu
- Centre for Developmental Neurobiology, King's College London, London, SE1 1UL, UK
| | - Matthew S Grubb
- Centre for Developmental Neurobiology, King's College London, London, SE1 1UL, UK.,FENS-Kavli Network of Excellence, Europe-wide
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69
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Shirao T, Hanamura K, Koganezawa N, Ishizuka Y, Yamazaki H, Sekino Y. The role of drebrin in neurons. J Neurochem 2017; 141:819-834. [PMID: 28199019 DOI: 10.1111/jnc.13988] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 12/27/2016] [Accepted: 01/11/2017] [Indexed: 01/13/2023]
Abstract
Drebrin is an actin-binding protein that changes the helical pitch of actin filaments (F-actin), and drebrin-decorated F-actin shows slow treadmilling and decreased rate of depolymerization. Moreover, the characteristic morphology of drebrin-decorated F-actin enables it to respond differently to the same signals from other actin cytoskeletons. Drebrin consists of two major isoforms, drebrin E and drebrin A. In the developing brain, drebrin E appears in migrating neurons and accumulates in the growth cones of axons and dendrites. Drebrin E-decorated F-actin links lamellipodium F-actin to microtubules in the growth cones. Then drebrin A appears at nascent synapses and drebrin A-decorated F-actin facilitates postsynaptic molecular assembly. In the adult brain, drebrin A-decorated F-actin is concentrated in the central region of dendritic spines. During long-term potentiation initiation, NMDA receptor-mediated Ca2+ influx induces the transient exodus of drebrin A-decorated F-actin via myosin II ATPase activation. Because of the unique physical characteristics of drebrin A-decorated F-actin, this exodus likely contributes to the facilitation of F-actin polymerization and spine enlargement. Additionally, drebrin reaccumulation in dendritic spines is observed after the exodus. In our drebrin exodus model of structure-based synaptic plasticity, reestablishment of drebrin A-decorated F-actin is necessary to keep the enlarged spine size during long-term potentiation maintenance. In this review, we introduce the genetic and biochemical properties of drebrin and the roles of drebrin in early stage of brain development, synaptic formation and synaptic plasticity. Further, we discuss the pathological relevance of drebrin loss in Alzheimer's disease. This article is part of the mini review series "60th Anniversary of the Japanese Society for Neurochemistry".
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Affiliation(s)
- Tomoaki Shirao
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Kenji Hanamura
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Noriko Koganezawa
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Yuta Ishizuka
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Hiroyuki Yamazaki
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Yuko Sekino
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.,Division of Pharmacology, National Institute of Health Sciences, Tokyo, Japan
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70
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Lauterborn JC, Kramár EA, Rice JD, Babayan AH, Cox CD, Karsten CA, Gall CM, Lynch G. Cofilin Activation Is Temporally Associated with the Cessation of Growth in the Developing Hippocampus. Cereb Cortex 2017; 27:2640-2651. [PMID: 27073215 PMCID: PMC5964364 DOI: 10.1093/cercor/bhw088] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Dendritic extension and synaptogenesis proceed at high rates in rat hippocampus during early postnatal life but markedly slow during the third week of development. The reasons for the latter, fundamental event are poorly understood. Here, we report that levels of phosphorylated (inactive) cofilin, an actin depolymerizing factor, decrease by 90% from postnatal days (pnds) 10 to 21. During the same period, levels of total and phosphorylated Arp2, which nucleates actin branches, increase. A search for elements that could explain the switch from inactive to active cofilin identified reductions in β1 integrin, TrkB, and LIM domain kinase 2b, upstream proteins that promote cofilin phosphorylation. Moreover, levels of slingshot 3, which dephosphorylates cofilin, increase during the period in which growth slows. Consistent with the cofilin results, in situ phalloidin labeling of F-actin demonstrated that spines and dendrites contained high levels of dynamic actin filaments during Week 2, but these fell dramatically by pnd 21. The results suggest that the change from inactive to constitutively active cofilin leads to a loss of dynamic actin filaments needed for process extension and thus the termination of spine formation and synaptogenesis. The relevance of these events to the emergence of memory-related synaptic plasticity is described.
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Affiliation(s)
| | | | | | | | | | | | - Christine M. Gall
- Department of Anatomy and Neurobiology
- Department of Neurobiology and Behavior
| | - Gary Lynch
- Department of Anatomy and Neurobiology
- Department of Psychiatry and Human Behavior, University of California at Irvine, Irvine, CA 92697, USA
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71
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Wang Y, Xu Y, Liu Q, Zhang Y, Gao Z, Yin M, Jiang N, Cao G, Yu B, Cao Z, Kou J. Myosin IIA-related Actomyosin Contractility Mediates Oxidative Stress-induced Neuronal Apoptosis. Front Mol Neurosci 2017; 10:75. [PMID: 28352215 PMCID: PMC5348499 DOI: 10.3389/fnmol.2017.00075] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/03/2017] [Indexed: 12/22/2022] Open
Abstract
Oxidative stress-induced neuronal apoptosis plays an important role in the progression of central nervous system (CNS) diseases. In our study, when neuronal cells were exposed to hydrogen peroxide (H2O2), an exogenous oxidant, cell apoptosis was observed with typical morphological changes including membrane blebbing, neurite retraction and cell contraction. The actomyosin system is considered to be responsible for the morphological changes, but how exactly it regulates oxidative stress-induced neuronal apoptosis and the distinctive functions of different myosin II isoforms remain unclear. We demonstrate that myosin IIA was required for neuronal contraction, while myosin IIB was required for neuronal outgrowth in normal conditions. During H2O2-induced neuronal apoptosis, myosin IIA, rather than IIB, interacted with actin filaments to generate contractile forces that lead to morphological changes. Moreover, myosin IIA knockout using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein-9 nuclease (CRISPR/Cas9) reduced H2O2-induced neuronal apoptosis and the associated morphological changes. We further demonstrate that caspase-3/Rho-associated kinase 1 (ROCK1) dependent phosphorylation of myosin light chain (MLC) was required for the formation of the myosin IIA-actin complex. Meanwhile, either inhibition of myosin II ATPase with blebbistatin or knockdown of myosin IIA with siRNA reversely attenuated caspase-3 activation, suggesting a positive feedback loop during oxidative stress-induced apoptosis. Based on our observation, myosin IIA-actin complex contributes to actomyosin contractility and is associated with the positive feedback loop of caspase-3/ROCK1/MLC pathway. This study unravels the biochemical and mechanistic mechanisms during oxidative stress-induced neuronal apoptosis and may be applicable for the development of therapies for CNS diseases.
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Affiliation(s)
- Yan Wang
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Yingqiong Xu
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Qian Liu
- Department of Neurology, Jinling Hospital, Nanjing University School of Medicine Nanjing, China
| | - Yuanyuan Zhang
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Zhen Gao
- Department of Medicine-Ather and Lipo, Baylor College of Medicine Houston, TX, USA
| | - Mingzhu Yin
- Department of Pathology, Yale School of Medicine New Haven, CT, USA
| | - Nan Jiang
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Guosheng Cao
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Boyang Yu
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Zhengyu Cao
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Junping Kou
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
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72
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Epilepsy and intellectual disability linked protein Shrm4 interaction with GABA BRs shapes inhibitory neurotransmission. Nat Commun 2017; 8:14536. [PMID: 28262662 PMCID: PMC5343488 DOI: 10.1038/ncomms14536] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 01/09/2017] [Indexed: 02/07/2023] Open
Abstract
Shrm4, a protein expressed only in polarized tissues, is encoded by the KIAA1202 gene, whose mutations have been linked to epilepsy and intellectual disability. However, a physiological role for Shrm4 in the brain is yet to be established. Here, we report that Shrm4 is localized to synapses where it regulates dendritic spine morphology and interacts with the C terminus of GABAB receptors (GABABRs) to control their cell surface expression and intracellular trafficking via a dynein-dependent mechanism. Knockdown of Shrm4 in rat severely impairs GABABR activity causing increased anxiety-like behaviour and susceptibility to seizures. Moreover, Shrm4 influences hippocampal excitability by modulating tonic inhibition in dentate gyrus granule cells, in a process involving crosstalk between GABABRs and extrasynaptic δ-subunit-containing GABAARs. Our data highlights a role for Shrm4 in synaptogenesis and in maintaining GABABR-mediated inhibition, perturbation of which may be responsible for the involvement of Shrm4 in cognitive disorders and epilepsy. Mutations in the gene encoding Shrm4 are associated with epilepsy and intellectual disability. The authors show that Shrm4 interacts with GABAB receptors and regulates tonic inhibition in the hippocampus, and knockdown of Shrm4 in rats leads to anxiety-like behaviour and seizures.
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73
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Yagi H, Takabayashi T, Xie MJ, Kuroda K, Sato M. Subcellular distribution of non-muscle myosin IIb is controlled by FILIP through Hsc70. PLoS One 2017; 12:e0172257. [PMID: 28234934 PMCID: PMC5325215 DOI: 10.1371/journal.pone.0172257] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 02/02/2017] [Indexed: 12/11/2022] Open
Abstract
The neuronal spine is a small, actin-rich dendritic or somatic protrusion that serves as the postsynaptic compartment of the excitatory synapse. The morphology of the spine reflects the activity of the synapse and is regulated by the dynamics of the actin cytoskeleton inside, which is controlled by actin binding proteins such as non-muscle myosin. Previously, we demonstrated that the subcellular localization and function of myosin IIb are regulated by its binding partner, filamin-A interacting protein (FILIP). However, how the subcellular distribution of myosin IIb is controlled by FILIP is not yet known. The objective of this study was to identify potential binding partners of FILIP that contribute to its regulation of non-muscle myosin IIb. Pull-down assays detected a 70-kDa protein that was identified by mass spectrometry to be the chaperone protein Hsc70. The binding of Hsc70 to FILIP was controlled by the adenosine triphosphatase (ATPase) activity of Hsc70. Further, FILIP bound to Hsc70 via a domain that was not required for binding non-muscle myosin IIb. Inhibition of ATPase activity of Hsc70 impaired the effect of FILIP on the subcellular distribution of non-muscle myosin IIb. Further, in primary cultured neurons, an inhibitor of Hsc70 impeded the morphological change in spines induced by FILIP. Collectively, these results demonstrate that Hsc70 interacts with FILIP to mediate its effects on non-muscle myosin IIb and to regulate spine morphology.
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Affiliation(s)
- Hideshi Yagi
- Department of Anatomy and Cell Biology, Hyogo College of Medicine, Hyogo, Japan.,Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Tetsuji Takabayashi
- Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Min-Jue Xie
- Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.,Research Center for Child Mental Development, University of Fukui, Fukui, Japan
| | - Kazuki Kuroda
- Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Makoto Sato
- Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.,Research Center for Child Mental Development, University of Fukui, Fukui, Japan.,United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Osaka, Japan.,Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
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74
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Koganezawa N, Hanamura K, Sekino Y, Shirao T. The role of drebrin in dendritic spines. Mol Cell Neurosci 2017; 84:85-92. [PMID: 28161364 DOI: 10.1016/j.mcn.2017.01.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/06/2016] [Accepted: 01/18/2017] [Indexed: 11/17/2022] Open
Abstract
Dendritic spines form typical excitatory synapses in the brain and their shapes vary depending on synaptic inputs. It has been suggested that the morphological changes of dendritic spines play an important role in synaptic plasticity. Dendritic spines contain a high concentration of actin, which has a central role in supporting cell motility, and polymerization of actin filaments (F-actin) is most likely involved in spine shape changes. Drebrin is an actin-binding protein that forms stable F-actin and is highly accumulated within dendritic spines. Drebrin has two isoforms, embryonic-type drebrin E and adult-type drebrin A, that change during development from E to A. Inhibition of drebrin A expression results in a delay of synapse formation and inhibition of postsynaptic protein accumulation, suggesting that drebrin A has an important role in spine maturation. In mature synapses, glutamate stimulation induces rapid spine-head enlargement during long-term potentiation (LTP) formation. LTP stimulation induces Ca2+ entry through N-methyl-d-aspartate (NMDA) receptors, which causes drebrin exodus from dendritic spines. Once drebrin exits from dendritic spine heads, the dynamic actin pool increases in spine heads to facilitate F-actin polymerization. To maintain enlarged spine heads, drebrin-decorated F-actin is thought to reform within the spine heads. Thus, drebrin plays a pivotal role in spine plasticity through regulation of F-actin.
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Affiliation(s)
- Noriko Koganezawa
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi 371-8511, Japan
| | - Kenji Hanamura
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi 371-8511, Japan
| | - Yuko Sekino
- Division of Pharmacology, National Institute of Health Sciences, Tokyo 158-8501, Japan
| | - Tomoaki Shirao
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi 371-8511, Japan.
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75
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Briggs SB, Blouin AM, Young EJ, Rumbaugh G, Miller CA. Memory disrupting effects of nonmuscle myosin II inhibition depend on the class of abused drug and brain region. ACTA ACUST UNITED AC 2017; 24:70-75. [PMID: 28096495 PMCID: PMC5238718 DOI: 10.1101/lm.043976.116] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/23/2016] [Indexed: 11/25/2022]
Abstract
Depolymerizing actin in the amygdala through nonmuscle myosin II inhibition (NMIIi) produces a selective, lasting, and retrieval-independent disruption of the storage of methamphetamine-associated memories. Here we report a similar disruption of memories associated with amphetamine, but not cocaine or morphine, by NMIIi. Reconsolidation appeared to be disrupted with cocaine. Unlike in the amygdala, methamphetamine-associated memory storage was not disrupted by NMIIi in the hippocampus, nucleus accumbens, or orbitofrontal cortex. NMIIi in the hippocampus did appear to disrupt reconsolidation. Identification of the unique mechanisms responsible for NMII-mediated, amygdala-dependent disruption of memory storage associated with the amphetamine class may enable induction of retrieval-independent vulnerability to other pathological memories.
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Affiliation(s)
- Sherri B Briggs
- Department of Metabolism & Aging, The Scripps Research Institute, Jupiter, Florida 33458, USA.,Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Ashley M Blouin
- Department of Metabolism & Aging, The Scripps Research Institute, Jupiter, Florida 33458, USA.,Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Erica J Young
- Department of Metabolism & Aging, The Scripps Research Institute, Jupiter, Florida 33458, USA.,Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Gavin Rumbaugh
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Courtney A Miller
- Department of Metabolism & Aging, The Scripps Research Institute, Jupiter, Florida 33458, USA.,Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, USA
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76
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Young EJ, Briggs SB, Rumbaugh G, Miller CA. Nonmuscle myosin II inhibition disrupts methamphetamine-associated memory in females and adolescents. Neurobiol Learn Mem 2017; 139:109-116. [PMID: 28082169 DOI: 10.1016/j.nlm.2017.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/30/2016] [Accepted: 01/02/2017] [Indexed: 12/31/2022]
Abstract
Memories associated with drug use can trigger strong motivation for the drug, which increases relapse vulnerability in substance use disorder (SUD). Currently there are no treatments for relapse to abuse of psychostimulants, such as methamphetamine (METH). We previously reported that storage of memories associated with METH, but not those for fear or food reward, and the concomitant spine density increase are disrupted in a retrieval-independent manner by depolymerizing actin in the basolateral amygdala complex (BLC) of adult male rats and mice. Similar results are achieved in males through intra-BLC or systemic inhibition of nonmuscle myosin II (NMII), a molecular motor that directly drives actin polymerization. Given the substantial differences in physiology between genders, we sought to determine if this immediate and selective disruption of METH-associated memory extends to adult females. A single intra-BLC infusion of the NMII inhibitor Blebbistatin (Blebb) produced a long-lasting disruption of context-induced drug seeking for at least 30days in female rats that mirrored our prior results in males. Furthermore, a single systemic injection of Blebb prior to testing disrupted METH-associated memory and the concomitant increase in BLC spine density in females. Importantly, as in males, the same manipulation had no effect on an auditory fear memory or associated BLC spine density. In addition, we established that the NMII-based disruption of METH-associated memory extends to both male and female adolescents. These findings provide further support that small molecular inhibitors of NMII have strong therapeutic potential for the prevention of relapse to METH abuse triggered by associative memories.
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Affiliation(s)
- Erica J Young
- Department of Metabolism & Aging, The Scripps Research Institute, Jupiter, FL, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | - Sherri B Briggs
- Department of Metabolism & Aging, The Scripps Research Institute, Jupiter, FL, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | - Gavin Rumbaugh
- Department of Metabolism & Aging, The Scripps Research Institute, Jupiter, FL, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | - Courtney A Miller
- Department of Metabolism & Aging, The Scripps Research Institute, Jupiter, FL, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA.
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77
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Sekino Y, Koganezawa N, Mizui T, Shirao T. Role of Drebrin in Synaptic Plasticity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1006:183-201. [DOI: 10.1007/978-4-431-56550-5_11] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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78
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MOCHIDA S. Millisecond Ca 2+ dynamics activate multiple protein cascades for synaptic vesicle control. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2017; 93:802-820. [PMID: 29225307 PMCID: PMC5790758 DOI: 10.2183/pjab.93.050] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 08/21/2017] [Indexed: 06/07/2023]
Abstract
For reliable transmission at chemical synapses, neurotransmitters must be released dynamically in response to neuronal activity in the form of action potentials. Stable synaptic transmission is dependent on the efficacy of transmitter release and the rate of resupplying synaptic vesicles to their release sites. Accurate regulation is conferred by proteins sensing Ca2+ entering through voltage-gated Ca2+ channels opened by an action potential. Presynaptic Ca2+ concentration changes are dynamic functions in space and time, with wide fluctuations associated with different rates of neuronal activity. Thus, regulation of transmitter release includes reactions involving multiple Ca2+-dependent proteins, each operating over a specific time window. Classically, studies of presynaptic proteins function favored large invertebrate presynaptic terminals. I have established a useful mammalian synapse model based on sympathetic neurons in culture. This review summarizes the use of this model synapse to study the roles of presynaptic proteins in neuronal activity for the control of transmitter release efficacy and synaptic vesicle recycling.
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Affiliation(s)
- Sumiko MOCHIDA
- Department of Physiology, Tokyo Medical University, Tokyo, Japan
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79
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Bennett MR, Arnold J, Hatton SN, Lagopoulos J. Regulation of fear extinction by long-term depression: The roles of endocannabinoids and brain derived neurotrophic factor. Behav Brain Res 2016; 319:148-164. [PMID: 27867101 DOI: 10.1016/j.bbr.2016.11.029] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 11/10/2016] [Accepted: 11/15/2016] [Indexed: 11/19/2022]
Abstract
The extinction of a conditioned fear response is of great interest in the search for a means of ameliorating adverse neurobiological changes resulting from stress. The discovery that endocannibinoid (EC) levels are inversely related to the extent of such stress, and that the amygdala is a primary site mediating stress, suggests that ECs in this brain region might play a major role in extinction. Supporting this are the observations that the basolateral complex of the amygdala shows an increase in ECs only during extinction and that early clinical trials indicate that cannabinoid-like agents, when taken orally by patients suffering from post traumatic stress disorder (PTSD), reduce insomnia and nightmares. In order to optimize the potential of these agents to ameliorate symptoms of PTSD four important questions need to be answered: first, what is the identity of the cells that release ECs in the amygdala during extinction; second, what are their sites of action; third, what roles do the ECs play in the alleviation of long- depression (LTD), a process central to extinction; and finally, to what extent does brain derived neurotrophic factor (BDNF) facilitate the release of ECs? A review of the relevant literature is presented in an attempt to answer these questions. It is suggested that the principal cell involved in EC synthesis and release during extinction is the so-called excitatory extinction neuron in the basal nucleus of the amygdala. Furthermore that the main site of action of the ECs is the adjacent calcitonin gene-related peptide inhibitory interneurons, whose normal role of blocking the excitatory neurons is greatly diminished. The molecular pathways leading (during extinction trials) to the synthesis and release of ECs from synaptic spines of extinction neurons, that is potentiated by BDNF, are also delineated in this review. Finally, consideration is given to how the autocrine action of BDNF, linked to the release of ECs, can lead to the sustained release of these, so maintaining extinction over long times.
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Affiliation(s)
- Maxwell R Bennett
- The Brain and Mind Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW, Australia.
| | - Jonathon Arnold
- The Brain and Mind Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW, Australia
| | - Sean N Hatton
- The Brain and Mind Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW, Australia
| | - Jim Lagopoulos
- The Brain and Mind Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW, Australia; The Sunshine Coast Mind and Neuroscience, Thompson Institute, The University of the Sunshine Coast, QLD, Australia
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80
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Bär J, Kobler O, van Bommel B, Mikhaylova M. Periodic F-actin structures shape the neck of dendritic spines. Sci Rep 2016; 6:37136. [PMID: 27841352 PMCID: PMC5107894 DOI: 10.1038/srep37136] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 10/25/2016] [Indexed: 11/17/2022] Open
Abstract
Most of the excitatory synapses on principal neurons of the forebrain are located on specialized structures called dendritic spines. Their morphology, comprising a spine head connected to the dendritic branch via a thin neck, provides biochemical and electrical compartmentalization during signal transmission. Spine shape is defined and tightly controlled by the organization of the actin cytoskeleton. Alterations in synaptic strength correlate with changes in the morphological appearance of the spine head and neck. Therefore, it is important to get a better understanding of the nanoscale organization of the actin cytoskeleton in dendritic spines. A periodic organization of the actin/spectrin lattice was recently discovered in axons and a small fraction of dendrites using super-resolution microscopy. Here we use a small probe phalloidin-Atto647N, to label F-actin in mature hippocampal primary neurons and in living hippocampal slices. STED nanoscopy reveals that in contrast to β-II spectrin antibody labelling, phalloidin-Atto647N stains periodic actin structures in all dendrites and the neck of nearly all dendritic spines, including filopodia-like spines. These findings extend the current view on F-actin organization in dendritic spines and may provide new avenues for understanding the structural changes in the spine neck during induction of synaptic plasticity, active organelle transport or tethering.
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Affiliation(s)
- Julia Bär
- DFG Emmy Noether Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Oliver Kobler
- Combinatorial Neuroimaging Core Facility (CNI), Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Bas van Bommel
- DFG Emmy Noether Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Marina Mikhaylova
- DFG Emmy Noether Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
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81
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Smith M, Piehler T, Benjamin R, Farizatto KL, Pait MC, Almeida MF, Ghukasyan VV, Bahr BA. Blast waves from detonated military explosive reduce GluR1 and synaptophysin levels in hippocampal slice cultures. Exp Neurol 2016; 286:107-115. [PMID: 27720798 DOI: 10.1016/j.expneurol.2016.10.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 09/27/2016] [Accepted: 10/04/2016] [Indexed: 12/15/2022]
Abstract
Explosives create shockwaves that cause blast-induced neurotrauma, one of the most common types of traumatic brain injury (TBI) linked to military service. Blast-induced TBIs are often associated with reduced cognitive and behavioral functions due to a variety of factors. To study the direct effects of military explosive blasts on brain tissue, we removed systemic factors by utilizing rat hippocampal slice cultures. The long-term slice cultures were briefly sealed air-tight in serum-free medium, lowered into a 37°C water-filled tank, and small 1.7-gram assemblies of cyclotrimethylene trinitramine (RDX) were detonated 15cm outside the tank, creating a distinct shockwave recorded at the culture plate position. Compared to control mock-treated groups of slices that received equal submerge time, 1-3 blast impacts caused a dose-dependent reduction in the AMPA receptor subunit GluR1. While only a small reduction was found in hippocampal slices exposed to a single RDX blast and harvested 1-2days later, slices that received two consecutive RDX blasts 4min apart exhibited a 26-40% reduction in GluR1, and the receptor subunit was further reduced by 64-72% after three consecutive blasts. Such loss correlated with increased levels of HDAC2, a histone deacetylase implicated in stress-induced reduction of glutamatergic transmission. No evidence of synaptic marker recovery was found at 72h post-blast. The presynaptic marker synaptophysin was found to have similar susceptibility as GluR1 to the multiple explosive detonations. In contrast to the synaptic protein reductions, actin levels were unchanged, spectrin breakdown was not detected, and Fluoro-Jade B staining found no indication of degenerating neurons in slices exposed to three RDX blasts, suggesting that small, sub-lethal explosives are capable of producing selective alterations to synaptic integrity. Together, these results indicate that blast waves from military explosive cause signs of synaptic compromise without producing severe neurodegeneration, perhaps explaining the cognitive and behavioral changes in those blast-induced TBI sufferers that have no detectable neuropathology.
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Affiliation(s)
- Marquitta Smith
- Biotechnology Research and Training Center, University of North Carolina-Pembroke, Pembroke, NC 28372, USA
| | - Thuvan Piehler
- U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005, USA
| | - Richard Benjamin
- U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005, USA
| | - Karen L Farizatto
- Biotechnology Research and Training Center, University of North Carolina-Pembroke, Pembroke, NC 28372, USA
| | - Morgan C Pait
- Biotechnology Research and Training Center, University of North Carolina-Pembroke, Pembroke, NC 28372, USA
| | - Michael F Almeida
- Biotechnology Research and Training Center, University of North Carolina-Pembroke, Pembroke, NC 28372, USA
| | - Vladimir V Ghukasyan
- Department of Cell Biology and Physiology, Neuroscience Center, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA
| | - Ben A Bahr
- Biotechnology Research and Training Center, University of North Carolina-Pembroke, Pembroke, NC 28372, USA.
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82
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State-dependent diffusion of actin-depolymerizing factor/cofilin underlies the enlargement and shrinkage of dendritic spines. Sci Rep 2016; 6:32897. [PMID: 27595610 PMCID: PMC5011767 DOI: 10.1038/srep32897] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/17/2016] [Indexed: 12/13/2022] Open
Abstract
Dendritic spines are the postsynaptic sites of most excitatory synapses in the brain, and spine enlargement and shrinkage give rise to long-term potentiation and depression of synapses, respectively. Because spine structural plasticity is accompanied by remodeling of actin scaffolds, we hypothesized that the filamentous actin regulatory protein cofilin plays a crucial role in this process. Here we investigated the diffusional properties of cofilin, the actin-severing and depolymerizing actions of which are activated by dephosphorylation. Cofilin diffusion was measured using fluorescently labeled cofilin fusion proteins and two-photon imaging. We show that cofilins are highly diffusible along dendrites in the resting state. However, during spine enlargement, wild-type cofilin and a phosphomimetic cofilin mutant remain confined to the stimulated spine, whereas a nonphosphorylatable mutant does not. Moreover, inhibition of cofilin phosphorylation with a competitive peptide disables spine enlargement, suggesting that phosphorylated-cofilin accumulation is a key regulator of enlargement, which is localized to individual spines. Conversely, spine shrinkage spreads to neighboring spines, even though triggered by weaker stimuli than enlargement. Diffusion of exogenous cofilin injected into a pyramidal neuron soma causes spine shrinkage and reduced PSD95 in spines, suggesting that diffusion of dephosphorylated endogenous cofilin underlies the spreading of spine shrinkage and long-term depression.
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83
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Havekes R, Park AJ, Tudor JC, Luczak VG, Hansen RT, Ferri SL, Bruinenberg VM, Poplawski SG, Day JP, Aton SJ, Radwańska K, Meerlo P, Houslay MD, Baillie GS, Abel T. Sleep deprivation causes memory deficits by negatively impacting neuronal connectivity in hippocampal area CA1. eLife 2016; 5. [PMID: 27549340 PMCID: PMC4996653 DOI: 10.7554/elife.13424] [Citation(s) in RCA: 169] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 07/29/2016] [Indexed: 12/18/2022] Open
Abstract
Brief periods of sleep loss have long-lasting consequences such as impaired memory consolidation. Structural changes in synaptic connectivity have been proposed as a substrate of memory storage. Here, we examine the impact of brief periods of sleep deprivation on dendritic structure. In mice, we find that five hours of sleep deprivation decreases dendritic spine numbers selectively in hippocampal area CA1 and increased activity of the filamentous actin severing protein cofilin. Recovery sleep normalizes these structural alterations. Suppression of cofilin function prevents spine loss, deficits in hippocampal synaptic plasticity, and impairments in long-term memory caused by sleep deprivation. The elevated cofilin activity is caused by cAMP-degrading phosphodiesterase-4A5 (PDE4A5), which hampers cAMP-PKA-LIMK signaling. Attenuating PDE4A5 function prevents changes in cAMP-PKA-LIMK-cofilin signaling and cognitive deficits associated with sleep deprivation. Our work demonstrates the necessity of an intact cAMP-PDE4-PKA-LIMK-cofilin activation-signaling pathway for sleep deprivation-induced memory disruption and reduction in hippocampal spine density. DOI:http://dx.doi.org/10.7554/eLife.13424.001 The demands of modern society means that millions of people do not get sufficient sleep on a daily basis. Sleep deprivation, even if only for brief periods, can impair learning and memory. In many cases, this impairment appears to be related to changes in the activity of a brain region called the hippocampus. However, the exact processes responsible for producing the effects of sleep deprivation remain unclear. During learning or forming a new memory, the connections between the relevant neurons in the brain change. Havekes et al. found that depriving mice of sleep for just five hours dramatically reduced the connectivity between neurons in the hippocampus. This reduction is caused by the increased activity of cofilin, a protein that breaks down the actin filaments that shape the connections between neurons. Havekes et al. then used a virus to introduce an inactive version of cofilin into hippocampal neurons to suppress the activity of the naturally present cofilin. This manipulation prevented both the loss of the connections between neurons and the memory deficits normally associated with sleep deprivation. Havekes et al. also found that recovery sleep leads to the re-wiring of neurons in the hippocampus. Future studies are now needed to determine how the neurons are able to re-wire themselves during recovery sleep. DOI:http://dx.doi.org/10.7554/eLife.13424.002
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Affiliation(s)
- Robbert Havekes
- Department of Biology, University of Pennsylvania, Philadelphia, United States.,Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Groningen, The Netherlands
| | - Alan J Park
- Department of Biology, University of Pennsylvania, Philadelphia, United States
| | - Jennifer C Tudor
- Department of Biology, University of Pennsylvania, Philadelphia, United States
| | - Vincent G Luczak
- Department of Biology, University of Pennsylvania, Philadelphia, United States
| | - Rolf T Hansen
- Department of Biology, University of Pennsylvania, Philadelphia, United States
| | - Sarah L Ferri
- Department of Biology, University of Pennsylvania, Philadelphia, United States
| | - Vibeke M Bruinenberg
- Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Groningen, The Netherlands
| | - Shane G Poplawski
- Department of Biology, University of Pennsylvania, Philadelphia, United States
| | - Jonathan P Day
- Institute of Cardiovascular and Medical Science, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Sara J Aton
- LSA Molecular, Cellular, and Developmental Biology, University of Michigan-Ann Arbor, Ann Arbor, United States
| | - Kasia Radwańska
- Laboratory of Molecular Basis of Behavior, Head Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Peter Meerlo
- Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Groningen, The Netherlands
| | - Miles D Houslay
- Institute of Pharmaceutical Science, King's College London, London, United Kingdom
| | - George S Baillie
- Institute of Cardiovascular and Medical Science, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Ted Abel
- Department of Biology, University of Pennsylvania, Philadelphia, United States
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84
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Paradoxical signaling regulates structural plasticity in dendritic spines. Proc Natl Acad Sci U S A 2016; 113:E5298-307. [PMID: 27551076 DOI: 10.1073/pnas.1610391113] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transient spine enlargement (3- to 5-min timescale) is an important event associated with the structural plasticity of dendritic spines. Many of the molecular mechanisms associated with transient spine enlargement have been identified experimentally. Here, we use a systems biology approach to construct a mathematical model of biochemical signaling and actin-mediated transient spine expansion in response to calcium influx caused by NMDA receptor activation. We have identified that a key feature of this signaling network is the paradoxical signaling loop. Paradoxical components act bifunctionally in signaling networks, and their role is to control both the activation and the inhibition of a desired response function (protein activity or spine volume). Using ordinary differential equation (ODE)-based modeling, we show that the dynamics of different regulators of transient spine expansion, including calmodulin-dependent protein kinase II (CaMKII), RhoA, and Cdc42, and the spine volume can be described using paradoxical signaling loops. Our model is able to capture the experimentally observed dynamics of transient spine volume. Furthermore, we show that actin remodeling events provide a robustness to spine volume dynamics. We also generate experimentally testable predictions about the role of different components and parameters of the network on spine dynamics.
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85
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Chazeau A, Giannone G. Organization and dynamics of the actin cytoskeleton during dendritic spine morphological remodeling. Cell Mol Life Sci 2016; 73:3053-73. [PMID: 27105623 PMCID: PMC11108290 DOI: 10.1007/s00018-016-2214-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/31/2016] [Accepted: 03/31/2016] [Indexed: 12/18/2022]
Abstract
In the central nervous system, most excitatory post-synapses are small subcellular structures called dendritic spines. Their structure and morphological remodeling are tightly coupled to changes in synaptic transmission. The F-actin cytoskeleton is the main driving force of dendritic spine remodeling and sustains synaptic plasticity. It is therefore essential to understand how changes in synaptic transmission can regulate the organization and dynamics of actin binding proteins (ABPs). In this review, we will provide a detailed description of the organization and dynamics of F-actin and ABPs in dendritic spines and will discuss the current models explaining how the actin cytoskeleton sustains both structural and functional synaptic plasticity.
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Affiliation(s)
- Anaël Chazeau
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, UMR 5297, 33000, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, CNRS, UMR 5297, 33000, Bordeaux, France
- Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Grégory Giannone
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, UMR 5297, 33000, Bordeaux, France.
- Interdisciplinary Institute for Neuroscience, CNRS, UMR 5297, 33000, Bordeaux, France.
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86
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Brettle M, Patel S, Fath T. Tropomyosins in the healthy and diseased nervous system. Brain Res Bull 2016; 126:311-323. [PMID: 27298153 DOI: 10.1016/j.brainresbull.2016.06.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 06/09/2016] [Accepted: 06/10/2016] [Indexed: 12/25/2022]
Abstract
Regulation of the actin cytoskeleton is dependent on a plethora of actin-associated proteins in all eukaryotic cells. The family of tropomyosins plays a key role in controlling the function of several of these actin-associated proteins and their access to actin filaments. In order to understand the regulation of the actin cytoskeleton in highly dynamic subcellular compartments of neurons such as growth cones of developing neurons and the synaptic compartment of mature neurons, it is pivotal to decipher the functional role of tropomyosins in the nervous system. In this review, we will discuss the current understanding and recent findings on the regulation of the actin cytoskeleton by tropomyosins and potential implication that this has for the dysregulation of the actin cytoskeleton in neurological diseases.
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Affiliation(s)
- Merryn Brettle
- Neurodegeneration and Repair Unit, School of Medical Sciences, University of New South Wales, 2052 Sydney, New South Wales, Australia
| | - Shrujna Patel
- Neurodegeneration and Repair Unit, School of Medical Sciences, University of New South Wales, 2052 Sydney, New South Wales, Australia
| | - Thomas Fath
- Neurodegeneration and Repair Unit, School of Medical Sciences, University of New South Wales, 2052 Sydney, New South Wales, Australia.
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87
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A highly soluble, non-phototoxic, non-fluorescent blebbistatin derivative. Sci Rep 2016; 6:26141. [PMID: 27241904 PMCID: PMC4886532 DOI: 10.1038/srep26141] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 04/20/2016] [Indexed: 12/15/2022] Open
Abstract
Blebbistatin is a commonly used molecular tool for the specific inhibition of various myosin II isoforms both in vitro and in vivo. Despite its popularity, the use of blebbistatin is hindered by its poor water-solubility (below 10 micromolar in aqueous buffer) and blue-light sensitivity, resulting in the photoconversion of the molecule, causing severe cellular phototoxicity in addition to its cytotoxicity. Furthermore, blebbistatin forms insoluble aggregates in water-based media above 10 micromolar with extremely high fluorescence and also high adherence to different types of surfaces, which biases its experimental usage. Here, we report a highly soluble (440 micromolar in aqueous buffer), non-fluorescent and photostable C15 amino-substituted derivative of blebbistatin, called para-aminoblebbistatin. Importantly, it is neither photo- nor cytotoxic, as demonstrated on HeLa cells and zebrafish embryos. Additionally, para-aminoblebbistatin bears similar myosin II inhibitory properties to blebbistatin or para-nitroblebbistatin (not to be confused with the C7 substituted nitroblebbistatin), tested on rabbit skeletal muscle myosin S1 and on M2 and HeLa cells. Due to its drastically improved solubility and photochemical feature, as well as lack of photo- or cytotoxicity, para-aminoblebbistatin may become a feasible replacement for blebbistatin, especially at applications when high concentrations of the inhibitor or blue light irradiation is required.
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88
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The calcium sensor Copine-6 regulates spine structural plasticity and learning and memory. Nat Commun 2016; 7:11613. [PMID: 27194588 PMCID: PMC4874034 DOI: 10.1038/ncomms11613] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 04/13/2016] [Indexed: 02/07/2023] Open
Abstract
Hippocampal long-term potentiation (LTP) represents the cellular response of excitatory synapses to specific patterns of high neuronal activity and is required for learning and memory. Here we identify a mechanism that requires the calcium-binding protein Copine-6 to translate the initial calcium signals into changes in spine structure. We show that Copine-6 is recruited from the cytosol of dendrites to postsynaptic spine membranes by calcium transients that precede LTP. Cpne6 knockout mice are deficient in hippocampal LTP, learning and memory. Hippocampal neurons from Cpne6 knockouts lack spine structural plasticity as do wild-type neurons that express a Copine-6 calcium mutant. The function of Copine-6 is based on its binding, activating and recruiting the Rho GTPase Rac1 to cell membranes. Consistent with this function, the LTP deficit of Cpne6 knockout mice is rescued by the actin stabilizer jasplakinolide. These data show that Copine-6 links activity-triggered calcium signals to spine structural plasticity necessary for learning and memory.
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89
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Abstract
The growth and migration of neurons require continuous remodelling of the neuronal cytoskeleton, providing a versatile cellular framework for force generation and guided movement, in addition to structural support. Actin filaments and microtubules are central to the dynamic action of the cytoskeleton and rapid advances in imaging technologies are enabling ever more detailed visualisation of the dynamic intracellular networks that they form. However, these filaments do not act individually and an expanding body of evidence emphasises the importance of actin-microtubule crosstalk in orchestrating cytoskeletal dynamics. Here, we summarise our current understanding of the structure and dynamics of actin and microtubules in isolation, before reviewing both the mechanisms and the molecular players involved in mediating actin-microtubule crosstalk in neurons.
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Affiliation(s)
- Charlotte H Coles
- Laboratory for Axon Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Ludwig-Erhard-Allee 2, 53175, Bonn, Germany.
| | - Frank Bradke
- Laboratory for Axon Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Ludwig-Erhard-Allee 2, 53175, Bonn, Germany.
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90
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Nonmuscle myosin IIB as a therapeutic target for the prevention of relapse to methamphetamine use. Mol Psychiatry 2016; 21:615-23. [PMID: 26239291 PMCID: PMC4740255 DOI: 10.1038/mp.2015.103] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 05/18/2015] [Accepted: 06/22/2015] [Indexed: 01/15/2023]
Abstract
Memories associated with drug use increase vulnerability to relapse in substance use disorder (SUD), and there are no pharmacotherapies for the prevention of relapse. Previously, we reported a promising finding that storage of memories associated with methamphetamine (METH), but not memories for fear or food reward, is vulnerable to disruption by actin depolymerization in the basolateral amygdala complex (BLC). However, actin is not a viable therapeutic target because of its numerous functions throughout the body. Here we report the discovery of a viable therapeutic target, nonmuscle myosin IIB (NMIIB), a molecular motor that supports memory by directly driving synaptic actin polymerization. A single intra-BLC treatment with Blebbistatin (Blebb), a small-molecule inhibitor of class II myosin isoforms, including NMIIB, produced a long-lasting disruption of context-induced drug seeking (at least 30 days). Further, postconsolidation genetic knockdown of Myh10, the heavy chain of the most highly expressed NMII in the BLC, was sufficient to produce METH-associated memory loss. Blebb was found to be highly brain penetrant. A single systemic injection of the compound selectively disrupted the storage of METH-associated memory and reversed the accompanying increase in BLC spine density. This effect was specific to METH-associated memory, as it had no effect on an auditory fear memory. The effect was also independent of retrieval, as METH-associated memory was disrupted 24 h after a single systemic injection of Blebb delivered in the home cage. Together, these results argue for the further development of small-molecule inhibitors of NMII as potential therapeutics for the prevention of SUD relapse triggered by drug associations.
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91
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Kojima N, Yasuda H, Hanamura K, Ishizuka Y, Sekino Y, Shirao T. Drebrin A regulates hippocampal LTP and hippocampus-dependent fear learning in adult mice. Neuroscience 2016; 324:218-26. [PMID: 26970584 DOI: 10.1016/j.neuroscience.2016.03.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 02/24/2016] [Accepted: 03/05/2016] [Indexed: 10/25/2022]
Abstract
Structural plasticity of dendritic spines, which underlies higher brain functions including learning and memory, is dynamically regulated by the actin cytoskeleton and its associated proteins. Drebrin A is an F-actin-binding protein preferentially expressed in the brain and localized in the dendritic spines of mature neurons. Isoform conversion from drebrin E to drebrin A and accumulation of the latter in dendritic spines occurs during synapse maturation. We have previously demonstrated that drebrin A plays a pivotal role in spine morphogenesis and plasticity. However, it is unclear whether drebrin A plays a specific role in processes required for structural plasticity, and whether drebrin E can substitute in this role. To answer these questions, we analyzed mutant mice (named DAKO mice), in which isoform conversion from drebrin E to drebrin A is disrupted. In DAKO mouse brain, drebrin E continues to be expressed throughout life instead of drebrin A. Electrophysiological studies using hippocampal slices revealed that long-term potentiation of CA1 synapses was impaired in adult DAKO mice, but not in adolescents. In parallel with this age-dependent impairment, DAKO mice exhibited impaired hippocampus-dependent fear learning in an age-dependent manner; the impairment was evident in adult mice, but not in adolescents. In addition, histological investigation revealed that the spine length of the apical dendrite of CA1 pyramidal cells was significantly longer in adult DAKO mice than in wild-type mice. Our data indicate that the roles of drebrin E and drebrin A in brain function are different from each other, that the isoform conversion of drebrin is critical, and that drebrin A is indispensable for normal synaptic plasticity and hippocampus-dependent fear memory in the adult brain.
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Affiliation(s)
- N Kojima
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan; Faculty of Life Sciences, Toyo University, Itakura, Gunma 374-0193, Japan; Institute of Life Innovation Studies, Toyo University, Itakura, Gunma 374-0193, Japan
| | - H Yasuda
- Education and Research Support Center, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - K Hanamura
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Y Ishizuka
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Y Sekino
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan; Division of Pharmacology, National Institute of Health Sciences, Tokyo, Tokyo 158-8501, Japan
| | - T Shirao
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
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92
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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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93
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Martorell-Riera A, Segarra-Mondejar M, Reina M, Martínez-Estrada OM, Soriano FX. Mitochondrial fragmentation in excitotoxicity requires ROCK activation. Cell Cycle 2016; 14:1365-9. [PMID: 25789413 DOI: 10.1080/15384101.2015.1022698] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Mitochondria morphology constantly changes through fission and fusion processes that regulate mitochondrial function, and it therefore plays a prominent role in cellular homeostasis. Cell death progression is associated with mitochondrial fission. Fission is mediated by the mainly cytoplasmic Drp1, which is activated by different post-translational modifications and recruited to mitochondria to perform its function. Our research and other studies have shown that in the early moments of excitotoxic insult Drp1 must be nitrosylated to mediate mitochondrial fragmentation in neurons. Nonetheless, mitochondrial fission is a multistep process in which filamentous actin assembly/disassembly and myosin-mediated mitochondrial constriction play prominent roles. Here we establish that in addition to nitric oxide production, excitotoxicity-induced mitochondrial fragmentation also requires activation of the actomyosin regulator ROCK. Although ROCK1 has been shown to phosphorylate and activate Drp1, experiments using phosphor-mutant forms of Drp1 in primary cortical neurons indicate that in excitotoxic conditions, ROCK does not act directly on Drp1 to mediate fission, but may act on the actomyosin complex. Thus, these data indicate that a wider range of signaling pathways than those that target Drp1 are amenable to be inhibited to prevent mitochondrial fragmentation as therapeutic option.
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Affiliation(s)
- Alejandro Martorell-Riera
- a Department of Cell Biology and CELLTEC-UB; Faculty of Biology ; University of Barcelona ; Barcelona , Spain
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94
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Newell-Litwa KA, Horwitz R, Lamers ML. Non-muscle myosin II in disease: mechanisms and therapeutic opportunities. Dis Model Mech 2015; 8:1495-515. [PMID: 26542704 PMCID: PMC4728321 DOI: 10.1242/dmm.022103] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The actin motor protein non-muscle myosin II (NMII) acts as a master regulator of cell morphology, with a role in several essential cellular processes, including cell migration and post-synaptic dendritic spine plasticity in neurons. NMII also generates forces that alter biochemical signaling, by driving changes in interactions between actin-associated proteins that can ultimately regulate gene transcription. In addition to its roles in normal cellular physiology, NMII has recently emerged as a critical regulator of diverse, genetically complex diseases, including neuronal disorders, cancers and vascular disease. In the context of these disorders, NMII regulatory pathways can be directly mutated or indirectly altered by disease-causing mutations. NMII regulatory pathway genes are also increasingly found in disease-associated copy-number variants, particularly in neuronal disorders such as autism and schizophrenia. Furthermore, manipulation of NMII-mediated contractility regulates stem cell pluripotency and differentiation, thus highlighting the key role of NMII-based pharmaceuticals in the clinical success of stem cell therapies. In this Review, we discuss the emerging role of NMII activity and its regulation by kinases and microRNAs in the pathogenesis and prognosis of a diverse range of diseases, including neuronal disorders, cancer and vascular disease. We also address promising clinical applications and limitations of NMII-based inhibitors in the treatment of these diseases and the development of stem-cell-based therapies.
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Affiliation(s)
- Karen A Newell-Litwa
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908, USA
| | - Rick Horwitz
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908, USA
| | - Marcelo L Lamers
- Department of Morphological Sciences, Institute of Basic Health Science, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 90610-010, Brazil
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95
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Wang S, Zhang J, Sheng T, Lu W, Miao D. Hippocampal ischemia causes deficits in local field potential and synaptic plasticity. J Biomed Res 2015; 29:370-9. [PMID: 26445570 PMCID: PMC4585431 DOI: 10.7555/jbr.29.20150010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 03/16/2015] [Accepted: 05/10/2015] [Indexed: 11/16/2022] Open
Abstract
The long-term enhancement in glutamate receptor mediated excitatory responses has been observed in stroke model. This pathological form of plasticity, termed post-ischemic long-term potentiation (i-LTP), points to functional reorganization after stroke. Little is known, however, about whether and how this i-LTP would affect subsequent induction of synaptic plasticity. Here, we first directly confirmed that i-LTP was induced in the endothelin-1-induced ischemia model as in other in vitro models. We also demonstrated increased expression of NR2B, CaMKII and p-CaMKII, which are reminiscent of i-LTP. We further induced LTP of field excitatory postsynaptic potentials (fEPSPs) on CA1 hippocampal neurons in peri-infarct regions of the endothelin-1-induced mini-stroke model. We found that LTP of fEPSPs, induced by high-frequency stimulation, displayed a progressive impairment at 12 and 24 hours after ischemia. Moreover, using in vivo multi-channel recording, we found that the local field potential, which represents electrical property of cell ensembles in more restricted regions, was also dampened at these two time points. These results suggest that i-LTP elevates the induction threshold of subsequent synaptic plasticity. Our data helps to deepen the knowledge of meta-synaptic regulation of plasticity after focal ischemia.
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Affiliation(s)
- Shaoli Wang
- The Research Center for Bone and Stem Cells, Department of Human Anatomy
| | - Jingyun Zhang
- The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University , Nanjing, Jiangsu 210096 , China
| | - Tao Sheng
- The Center of Metabolic Disease Research, Nanjing Medical University , Nanjing, Jiangsu 210029 , China
| | - Wei Lu
- Department of Neurobiology ; The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University , Nanjing, Jiangsu 210096 , China
| | - Dengshun Miao
- The Research Center for Bone and Stem Cells, Department of Human Anatomy
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96
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Bu Y, Wang N, Wang S, Sheng T, Tian T, Chen L, Pan W, Zhu M, Luo J, Lu W. Myosin IIb-dependent Regulation of Actin Dynamics Is Required for N-Methyl-D-aspartate Receptor Trafficking during Synaptic Plasticity. J Biol Chem 2015; 290:25395-410. [PMID: 26330558 DOI: 10.1074/jbc.m115.644229] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Indexed: 12/21/2022] Open
Abstract
N-Methyl-d-aspartate receptor (NMDAR) synaptic incorporation changes the number of NMDARs at synapses and is thus critical to various NMDAR-dependent brain functions. To date, the molecules involved in NMDAR trafficking and the underlying mechanisms are poorly understood. Here, we report that myosin IIb is an essential molecule in NMDAR synaptic incorporation during PKC- or θ burst stimulation-induced synaptic plasticity. Moreover, we demonstrate that myosin light chain kinase (MLCK)-dependent actin reorganization contributes to NMDAR trafficking. The findings from additional mutual occlusion experiments demonstrate that PKC and MLCK share a common signaling pathway in NMDAR-mediated synaptic regulation. Because myosin IIb is the primary substrate of MLCK and can regulate actin dynamics during synaptic plasticity, we propose that the MLCK- and myosin IIb-dependent regulation of actin dynamics is required for NMDAR trafficking during synaptic plasticity. This study provides important insights into a mechanical framework for understanding NMDAR trafficking associated with synaptic plasticity.
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Affiliation(s)
- Yunfei Bu
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
| | - Ning Wang
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029, China, the Key Laboratory of Developmental Genes and Human Disease of the Ministry of Education of China, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, China
| | - Shaoli Wang
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029, China, the Key Laboratory of Developmental Genes and Human Disease of the Ministry of Education of China, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, China
| | - Tao Sheng
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029, China, the Key Laboratory of Developmental Genes and Human Disease of the Ministry of Education of China, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, China
| | - Tian Tian
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
| | - Linlin Chen
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
| | - Weiwei Pan
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
| | - Minsheng Zhu
- the Key Laboratory of Model Animal for Disease Study of the Ministry of Education of China, Model Animal Research Center, Nanjing University, Nanjing, Jiangsu Province 210063, China, and
| | - Jianhong Luo
- the Department of Neurobiology, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang Province Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province 310058, China
| | - Wei Lu
- From the Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province 210029, China, the Key Laboratory of Developmental Genes and Human Disease of the Ministry of Education of China, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, China, the Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province 226001, China,
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97
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Neural activity selects myosin IIB and VI with a specific time window in distinct dynamin isoform-mediated synaptic vesicle reuse pathways. J Neurosci 2015; 35:8901-13. [PMID: 26063922 DOI: 10.1523/jneurosci.5028-14.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Presynaptic nerve terminals must maintain stable neurotransmissions via synaptic vesicle (SV) resupply despite encountering wide fluctuations in the number and frequency of incoming action potentials (APs). However, the molecular mechanism linking variation in neural activity to SV resupply is unknown. Myosins II and VI are actin-based cytoskeletal motors that drive dendritic actin dynamics and membrane transport, respectively, at brain synapses. Here we combined genetic knockdown or molecular dysfunction and direct physiological measurement of fast synaptic transmission from paired rat superior cervical ganglion neurons in culture to show that myosins IIB and VI work individually in SV reuse pathways, having distinct dependency and time constants with physiological AP frequency. Myosin VI resupplied the readily releasable pool (RRP) with slow kinetics independently of firing rates but acted quickly within 50 ms after AP. Under high-frequency AP firing, myosin IIB resupplied the RRP with fast kinetics in a slower time window of 200 ms. Knockdown of both myosin and dynamin isoforms by mixed siRNA microinjection revealed that myosin IIB-mediated SV resupply follows amphiphysin/dynamin-1-mediated endocytosis, while myosin VI-mediated SV resupply follows dynamin-3-mediated endocytosis. Collectively, our findings show how distinct myosin isoforms work as vesicle motors in appropriate SV reuse pathways associated with specific firing patterns.
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98
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Cheng N, Hu X, Tian T, Lu W. PKMζ knockdown disrupts post-ischemic long-term potentiation via inhibiting postsynaptic expression of aminomethyl phosphonic acid receptors. J Biomed Res 2015; 29:241-9. [PMID: 26060448 PMCID: PMC4449492 DOI: 10.7555/jbr.28.20140033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 03/11/2014] [Accepted: 05/07/2014] [Indexed: 11/12/2022] Open
Abstract
Post-ischemic long-term potentiation (i-LTP) is a pathological form of plasticity that was observed in glutamate receptor-mediated neurotransmission after stroke and may exert a detrimental effect via facilitating excitotoxic damage. The mechanism underlying i-LTP, however, remains less understood. By employing electrophysiological recording and immunofluorescence assay on hippocampal slices and cultured neurons, we found that protein kinase Mζ (PKMζ), an atypical protein kinase C isoform, was involved in enhancing aminomethyl phosphonic acid (AMPA) receptor (AMPAR) expression after i-LTP induction. PKMζ knockdown attenuated postsynaptic expression of AMPA receptors and disrupted i-LTP. Consistently, we observed less neuronal death of cultured hippocampal cells with PKMζ knockdown. Meanwhile, these findings indicate that PKMζ plays an important role in i-LTP by regulating postsynaptic expression of AMPA receptors. This work adds new knowledge to the mechanism of i-LTP, and thus is helpful to find the potential target for clinical therapy of ischemic stroke.
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Affiliation(s)
- Nan Cheng
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Xiaoqiao Hu
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Tian Tian
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Wei Lu
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu 210029, China
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99
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Ozkan ED, Aceti M, Creson TK, Rojas CS, Hubbs CR, McGuire MN, Kakad PP, Miller CA, Rumbaugh G. Input-specific regulation of hippocampal circuit maturation by non-muscle myosin IIB. J Neurochem 2015; 134:429-44. [PMID: 25931194 DOI: 10.1111/jnc.13146] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 04/04/2015] [Accepted: 04/08/2015] [Indexed: 12/18/2022]
Abstract
Myh9 and Myh10, which encode two major isoforms of non-muscle myosin II expressed in the brain, have emerged as risk factors for developmental brain disorders. Myosin II motors regulate neuronal cytoskeletal dynamics leading to optimization of synaptic plasticity and memory formation. However, the role of these motor complexes in brain development remains poorly understood. Here, we disrupted the in vivo expression of Myh9 and/or Myh10 in developing hippocampal neurons to determine how these motors contribute to circuit maturation in this brain area important for cognition. We found that Myh10 ablation in early postnatal, but not mature, CA1 pyramidal neurons reduced excitatory synaptic function in the Schaffer collateral pathway, whereas more distal inputs to CA1 neurons were relatively unaffected. Myh10 ablation in young neurons also selectively impaired the elongation of oblique dendrites that receive Schaffer collateral inputs, whereas the structure of distal dendrites was normal. We observed normal spine density and spontaneous excitatory currents in these neurons, indicating that Myh10 KO impaired proximal pathway synaptic maturation through disruptions to dendritic development rather than post-synaptic strength or spine morphogenesis. To address possible redundancy and/or compensation by other Myosin II motors expressed in neurons, we performed similar experiments in Myh9 null neurons. In contrast to findings in Myh10 mutants, evoked synaptic function in young Myh9 KO hippocampal neurons was normal. Data obtained from double Myh9/Myh10 KO neurons largely resembled the MyH10 KO synaptic phenotype. These data indicate that Myosin IIB is a key molecular factor that guides input-specific circuit maturation in the developing hippocampus. Non-muscle myosin II is an actin binding protein with three isoforms in the brain (IIA, IIB and IIC) encoded by the myh9, myh10, and myh14 genes in mice, respectively. We have studied the structure and the function of hippocampal CA1 neurons missing NMIIB and/or NMIIA proteins at different times during development. We have discovered that NMIIB is the major isoform regulating Schaffer collateral inputs, and that this regulation is restricted to early postnatal development.
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Affiliation(s)
- Emin D Ozkan
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, USA
| | - Massimiliano Aceti
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, USA
| | - Thomas K Creson
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, USA
| | - Camilo S Rojas
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, USA
| | - Christopher R Hubbs
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, USA
| | - Megan N McGuire
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, USA
| | - Priyanka P Kakad
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, USA
| | - Courtney A Miller
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, USA.,Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, Florida, USA
| | - Gavin Rumbaugh
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, USA
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100
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Abstract
Dendritic protein synthesis and actin cytoskeleton reorganization are important events required for the consolidation of hippocampal LTP and memory. However, the temporal and spatial relationships between these two processes remain unclear. Here, we report that treatment of adult rat hippocampal slices with BDNF or with tetraethylammonium (TEA), which induces a chemical form of LTP, produces a rapid and transient increase in RhoA protein levels. Changes in RhoA were restricted to dendritic spines of CA3 and CA1 and require de novo protein synthesis regulated by mammalian target of rapamycin (mTOR). BDNF-mediated stimulation of RhoA activity, cofilin phosphorylation, and actin polymerization were completely suppressed by protein synthesis inhibitors. Furthermore, intrahippocampal injections of RhoA antisense oligodeoxynucleotides inhibited theta burst stimulation (TBS)-induced RhoA upregulation in dendritic spines and prevented LTP consolidation. Addition of calpain inhibitors after BDNF or TEA treatment maintained RhoA levels elevated and prolonged the effects of BDNF and TEA on actin polymerization. Finally, the use of isoform-selective calpain inhibitors revealed that calpain-2 was involved in RhoA synthesis, whereas calpain-1 mediated RhoA degradation. Overall, this mechanism provides a novel link between dendritic protein synthesis and reorganization of the actin cytoskeleton in hippocampal dendritic spines during LTP consolidation.
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