101
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Fu AKY, Ip NY. Regulation of postsynaptic signaling in structural synaptic plasticity. Curr Opin Neurobiol 2017; 45:148-155. [DOI: 10.1016/j.conb.2017.05.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 04/28/2017] [Accepted: 05/12/2017] [Indexed: 02/05/2023]
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102
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Role of G Protein-Coupled Receptors in the Regulation of Structural Plasticity and Cognitive Function. Molecules 2017; 22:molecules22071239. [PMID: 28737723 PMCID: PMC6152405 DOI: 10.3390/molecules22071239] [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: 06/23/2017] [Accepted: 07/14/2017] [Indexed: 12/26/2022] Open
Abstract
Cognition and other higher brain functions are known to be intricately associated with the capacity of neural circuits to undergo structural reorganization. Structural remodelling of neural circuits, or structural plasticity, in the hippocampus plays a major role in learning and memory. Dynamic modifications of neuronal connectivity in the form of dendritic spine morphology alteration, as well as synapse formation and elimination, often result in the strengthening or weakening of specific neural circuits that determine synaptic plasticity. Changes in dendritic complexity and synapse number are mediated by cellular processes that are regulated by extracellular signals such as neurotransmitters and neurotrophic factors. As many neurotransmitters act on G protein-coupled receptors (GPCRs), it has become increasingly apparent that GPCRs can regulate structural plasticity through a myriad of G protein-dependent pathways and non-canonical signals. A thorough understanding of how GPCRs exert their regulatory influence on dendritic spine morphogenesis may provide new insights for treating cognitive impairment and decline in various age-related diseases. In this article, we review the evidence of GPCR-mediated regulation of structural plasticity, with a special emphasis on the involvement of common as well as distinct signalling pathways that are regulated by major neurotransmitters.
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103
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Miller MB, Yan Y, Machida K, Kiraly DD, Levy AD, Wu YI, Lam TT, Abbott T, Koleske AJ, Eipper BA, Mains RE. Brain Region and Isoform-Specific Phosphorylation Alters Kalirin SH2 Domain Interaction Sites and Calpain Sensitivity. ACS Chem Neurosci 2017; 8:1554-1569. [PMID: 28418645 DOI: 10.1021/acschemneuro.7b00076] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Kalirin7 (Kal7), a postsynaptic Rho GDP/GTP exchange factor (RhoGEF), plays a crucial role in long-term potentiation and in the effects of cocaine on behavior and spine morphology. The KALRN gene has been linked to schizophrenia and other disorders of synaptic function. Mass spectrometry was used to quantify phosphorylation at 26 sites in Kal7 from individual adult rat nucleus accumbens and prefrontal cortex before and after exposure to acute or chronic cocaine. Region- and isoform-specific phosphorylation was observed along with region-specific effects of cocaine on Kal7 phosphorylation. Evaluation of the functional significance of multisite phosphorylation in a complex protein like Kalirin is difficult. With the identification of five tyrosine phosphorylation (pY) sites, a panel of 71 SH2 domains was screened, identifying subsets that interacted with multiple pY sites in Kal7. In addition to this type of reversible interaction, endoproteolytic cleavage by calpain plays an essential role in long-term potentiation. Calpain cleaved Kal7 at two sites, separating the N-terminal domain, which affects spine length, and the PDZ binding motif from the GEF domain. Mutations preventing phosphorylation did not affect calpain sensitivity or GEF activity; phosphomimetic mutations at specific sites altered protein stability, increased calpain sensitivity, and reduced GEF activity.
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Affiliation(s)
| | | | | | - Drew D. Kiraly
- Department
of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York 10029, United States
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Synaptic GAP and GEF Complexes Cluster Proteins Essential for GTP Signaling. Sci Rep 2017; 7:5272. [PMID: 28706196 PMCID: PMC5509740 DOI: 10.1038/s41598-017-05588-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 05/31/2017] [Indexed: 12/04/2022] Open
Abstract
GTPase-activating proteins (GAPs) and guanine exchange factors (GEFs) play essential roles in regulating the activity of small GTPases. Several GAPs and GEFs have been shown to be present at the postsynaptic density (PSD) within excitatory glutamatergic neurons and regulate the activity of glutamate receptors. However, it is not known how synaptic GAP and GEF proteins are organized within the PSD signaling machinery, if they have overlapping interaction networks, or if they associate with proteins implicated in contributing to psychiatric disease. Here, we determine the interactomes of three interacting GAP/GEF proteins at the PSD, including the RasGAP Syngap1, the ArfGAP Agap2, and the RhoGEF Kalirin, which includes a total of 280 interactions. We describe the functional properties of each interactome and show that these GAP/GEF proteins are highly associated with and cluster other proteins directly involved in GTPase signaling mechanisms. We also utilize Agap2 as an example of GAP/GEFs localized within multiple neuronal compartments and determine an additional 110 interactions involving Agap2 outside of the PSD. Functional analysis of PSD and non-PSD interactomes illustrates both common and unique functions of Agap2 determined by its subcellular location. Furthermore, we also show that these GAPs/GEFs associate with several proteins involved in psychiatric disease.
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105
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Increased Training Intensity Induces Proper Membrane Localization of Actin Remodeling Proteins in the Hippocampus Preventing Cognitive Deficits: Implications for Fragile X Syndrome. Mol Neurobiol 2017; 55:4529-4542. [DOI: 10.1007/s12035-017-0666-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 06/19/2017] [Indexed: 10/19/2022]
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106
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Deans PM, Raval P, Sellers KJ, Gatford NJ, Halai S, Duarte RR, Shum C, Warre-Cornish K, Kaplun VE, Cocks G, Hill M, Bray NJ, Price J, Srivastava DP. Psychosis Risk Candidate ZNF804A Localizes to Synapses and Regulates Neurite Formation and Dendritic Spine Structure. Biol Psychiatry 2017; 82:49-61. [PMID: 27837918 PMCID: PMC5482321 DOI: 10.1016/j.biopsych.2016.08.038] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 08/21/2016] [Accepted: 08/22/2016] [Indexed: 12/11/2022]
Abstract
BACKGROUND Variation in the gene encoding zinc finger binding protein 804A (ZNF804A) is associated with schizophrenia and bipolar disorder. Evidence suggests that ZNF804A is a regulator of gene transcription and is present in nuclear and extranuclear compartments. However, a detailed examination of ZNF804A distribution and its neuronal functions has yet to be performed. METHODS The localization of ZNF804A protein was examined in neurons derived from human neural progenitor cells, human induced pluripotent stem cells, or in primary rat cortical neurons. In addition, small interfering RNA-mediated knockdown of ZNF804A was conducted to determine its role in neurite formation, maintenance of dendritic spine morphology, and responses to activity-dependent stimulations. RESULTS Endogenous ZNF804A protein localized to somatodendritic compartments and colocalized with the putative synaptic markers in young neurons derived from human neural progenitor cells and human induced pluripotent stem cells. In mature rat neurons, Zfp804A, the homolog of ZNF804A, was present in a subset of dendritic spines and colocalized with synaptic proteins in specific nanodomains, as determined by super-resolution microscopy. Interestingly, knockdown of ZNF804A attenuated neurite outgrowth in young neurons, an effect potentially mediated by reduced neuroligin-4 expression. Furthermore, knockdown of ZNF804A in mature neurons resulted in the loss of dendritic spine density and impaired responses to activity-dependent stimulation. CONCLUSIONS These data reveal a novel subcellular distribution for ZNF804A within somatodendritic compartments and a nanoscopic organization at excitatory synapses. Moreover, our results suggest that ZNF804A plays an active role in neurite formation, maintenance of dendritic spines, and activity-dependent structural plasticity.
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Affiliation(s)
- P.J. Michael Deans
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London
| | - Pooja Raval
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London
| | - Katherine J. Sellers
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London
| | - Nicholas J.F. Gatford
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London
| | - Sanjay Halai
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London
| | - Rodrigo R.R. Duarte
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London
| | - Carole Shum
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London
| | - Katherine Warre-Cornish
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London
| | - Victoria E. Kaplun
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London
| | - Graham Cocks
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London
| | - Matthew Hill
- MRC Centre for Neuropsychiatric Genetics & Genomics, Cardiff, United Kingdom,Neuroscience and Mental Health Research Institute, College of Biomedical and Life Sciences, Cardiff University School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Nicholas J. Bray
- MRC Centre for Neuropsychiatric Genetics & Genomics, Cardiff, United Kingdom
| | - Jack Price
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London,MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London; United Kingdom
| | - Deepak P. Srivastava
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London,MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London; United Kingdom,Address correspondence to: Deepak P. Srivastava, Ph.D., Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, SE5 9RT, United KingdomDepartment of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King’s College LondonLondonSE5 9RTUnited Kingdom
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The Small GTPase Rac1 Contributes to Extinction of Aversive Memories of Drug Withdrawal by Facilitating GABA A Receptor Endocytosis in the vmPFC. J Neurosci 2017. [PMID: 28630256 DOI: 10.1523/jneurosci.3859-16.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Extinction of aversive memories has been a major concern in neuropsychiatric disorders, such as anxiety disorders and drug addiction. However, the mechanisms underlying extinction of aversive memories are not fully understood. Here, we report that extinction of conditioned place aversion (CPA) to naloxone-precipitated opiate withdrawal in male rats activates Rho GTPase Rac1 in the ventromedial prefrontal cortex (vmPFC) in a BDNF-dependent manner, which determines GABAA receptor (GABAAR) endocytosis via triggering synaptic translocation of activity-regulated cytoskeleton-associated protein (Arc) through facilitating actin polymerization. Active Rac1 is essential and sufficient for GABAAR endocytosis and CPA extinction. Knockdown of Rac1 expression within the vmPFC of rats using Rac1-shRNA suppressed GABAAR endocytosis and CPA extinction, whereas expression of a constitutively active form of Rac1 accelerated GABAAR endocytosis and CPA extinction. The crucial role of GABAAR endocytosis in the LTP induction and CPA extinction is evinced by the findings that blockade of GABAAR endocytosis by a dynamin function-blocking peptide (Myr-P4) abolishes LTP induction and CPA extinction. Thus, the present study provides first evidence that Rac1-dependent GABAAR endocytosis plays a crucial role in extinction of aversive memories and reveals the sequence of molecular events that contribute to learning experience modulation of synaptic GABAAR endocytosis.SIGNIFICANCE STATEMENT This study reveals that Rac1-dependent GABAAR endocytosis plays a crucial role in extinction of aversive memories associated with drug withdrawal and identifies Arc as a downstream effector of Rac1 regulations of synaptic plasticity as well as learning and memory, thereby suggesting therapeutic targets to promote extinction of the unwanted memories.
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Genetic Variant of Kalirin Gene Is Associated with Ischemic Stroke in a Chinese Han Population. BIOMED RESEARCH INTERNATIONAL 2017; 2017:6594271. [PMID: 28706949 PMCID: PMC5494542 DOI: 10.1155/2017/6594271] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Revised: 04/10/2017] [Accepted: 05/18/2017] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Ischemic stroke is a complex disorder resulting from the interplay of genetic and environmental factors. Previous studies showed that kalirin gene variations were associated with cardiovascular disease. However, the association between this gene and ischemic stroke was unknown. We performed this study to confirm if kalirin gene variation was associated with ischemic stroke. METHODS We enrolled 385 ischemic stroke patients and 362 controls from China. Three SNPs of kalirin gene were genotyped by means of ligase detection reaction-PCR method. Data was processed with SPSS and SHEsis platform. RESULTS SNP rs7620580 (dominant model: OR = 1.590, p = 0.002 and adjusted OR = 1.662, p = 0.014; additive model: OR = 1.490, p = 0.002 and adjusted OR = 1.636, p = 0.005; recessive model: OR = 2.686, p = 0.039) and SNP rs1708303 (dominant model: OR = 1.523, p = 0.007 and adjusted OR = 1.604, p = 0.028; additive model: OR = 1.438, p = 0.01 and adjusted OR = 1.476, p = 0.039) were associated with ischemic stroke. The GG genotype and G allele of SNP rs7620580 were associated with a risk for ischemic stroke with an adjusted OR of 3.195 and an OR of 1.446, respectively. Haplotype analysis revealed that A-T-G,G-T-A, and A-T-A haplotypes were associated with ischemic stroke. CONCLUSIONS Our results provide evidence that kalirin gene variations were associated with ischemic stroke in the Chinese Han population.
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109
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Qiao H, An SC, Xu C, Ma XM. Role of proBDNF and BDNF in dendritic spine plasticity and depressive-like behaviors induced by an animal model of depression. Brain Res 2017; 1663:29-37. [DOI: 10.1016/j.brainres.2017.02.020] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 02/14/2017] [Accepted: 02/20/2017] [Indexed: 10/20/2022]
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110
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Activity-Induced Synaptic Structural Modifications by an Activator of Integrin Signaling at the Drosophila Neuromuscular Junction. J Neurosci 2017; 37:3246-3263. [PMID: 28219985 DOI: 10.1523/jneurosci.3128-16.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/08/2017] [Accepted: 02/14/2017] [Indexed: 11/21/2022] Open
Abstract
Activity-induced synaptic structural modification is crucial for neural development and synaptic plasticity, but the molecular players involved in this process are not well defined. Here, we report that a protein named Shriveled (Shv) regulates synaptic growth and activity-dependent synaptic remodeling at the Drosophila neuromuscular junction. Depletion of Shv causes synaptic overgrowth and an accumulation of immature boutons. We find that Shv physically and genetically interacts with βPS integrin. Furthermore, Shv is secreted during intense, but not mild, neuronal activity to acutely activate integrin signaling, induce synaptic bouton enlargement, and increase postsynaptic glutamate receptor abundance. Consequently, loss of Shv prevents activity-induced synapse maturation and abolishes post-tetanic potentiation, a form of synaptic plasticity. Our data identify Shv as a novel trans-synaptic signal secreted upon intense neuronal activity to promote synapse remodeling through integrin receptor signaling.SIGNIFICANCE STATEMENT The ability of neurons to rapidly modify synaptic structure in response to neuronal activity, a process called activity-induced structural remodeling, is crucial for neuronal development and complex brain functions. The molecular players that are important for this fundamental biological process are not well understood. Here we show that the Shriveled (Shv) protein is required during development to maintain normal synaptic growth. We further demonstrate that Shv is selectively released during intense neuronal activity, but not mild neuronal activity, to acutely activate integrin signaling and trigger structural modifications at the Drosophila neuromuscular junction. This work identifies Shv as a key modulator of activity-induced structural remodeling and suggests that neurons use distinct molecular cues to differentially modulate synaptic growth and remodeling to meet synaptic demand.
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111
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A Novel Human CAMK2A Mutation Disrupts Dendritic Morphology and Synaptic Transmission, and Causes ASD-Related Behaviors. J Neurosci 2017; 37:2216-2233. [PMID: 28130356 DOI: 10.1523/jneurosci.2068-16.2017] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 01/09/2017] [Accepted: 01/17/2017] [Indexed: 11/21/2022] Open
Abstract
Characterizing the functional impact of novel mutations linked to autism spectrum disorder (ASD) provides a deeper mechanistic understanding of the underlying pathophysiological mechanisms. Here we show that a de novo Glu183 to Val (E183V) mutation in the CaMKIIα catalytic domain, identified in a proband diagnosed with ASD, decreases both CaMKIIα substrate phosphorylation and regulatory autophosphorylation, and that the mutated kinase acts in a dominant-negative manner to reduce CaMKIIα-WT autophosphorylation. The E183V mutation also reduces CaMKIIα binding to established ASD-linked proteins, such as Shank3 and subunits of l-type calcium channels and NMDA receptors, and increases CaMKIIα turnover in intact cells. In cultured neurons, the E183V mutation reduces CaMKIIα targeting to dendritic spines. Moreover, neuronal expression of CaMKIIα-E183V increases dendritic arborization and decreases both dendritic spine density and excitatory synaptic transmission. Mice with a knock-in CaMKIIα-E183V mutation have lower total forebrain CaMKIIα levels, with reduced targeting to synaptic subcellular fractions. The CaMKIIα-E183V mice also display aberrant behavioral phenotypes, including hyperactivity, social interaction deficits, and increased repetitive behaviors. Together, these data suggest that CaMKIIα plays a previously unappreciated role in ASD-related synaptic and behavioral phenotypes.SIGNIFICANCE STATEMENT Many autism spectrum disorder (ASD)-linked mutations disrupt the function of synaptic proteins, but no single gene accounts for >1% of total ASD cases. The molecular networks and mechanisms that couple the primary deficits caused by these individual mutations to core behavioral symptoms of ASD remain poorly understood. Here, we provide the first characterization of a mutation in the gene encoding CaMKIIα linked to a specific neuropsychiatric disorder. Our findings demonstrate that this ASD-linked de novo CAMK2A mutation disrupts multiple CaMKII functions, induces synaptic deficits, and causes ASD-related behavioral alterations, providing novel insights into the synaptic mechanisms contributing to ASD.
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112
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Wnt5a is essential for hippocampal dendritic maintenance and spatial learning and memory in adult mice. Proc Natl Acad Sci U S A 2017; 114:E619-E628. [PMID: 28069946 PMCID: PMC5278440 DOI: 10.1073/pnas.1615792114] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Stability of neuronal connectivity is critical for brain functions, and morphological perturbations are associated with neurodegenerative disorders. However, how neuronal morphology is maintained in the adult brain remains poorly understood. Here, we identify Wnt5a, a member of the Wnt family of secreted morphogens, as an essential factor in maintaining dendritic architecture in the adult hippocampus and for related cognitive functions in mice. Wnt5a expression in hippocampal neurons begins postnatally, and its deletion attenuated CaMKII and Rac1 activity, reduced GluN1 glutamate receptor expression, and impaired synaptic plasticity and spatial learning and memory in 3-mo-old mice. With increased age, Wnt5a loss caused progressive attrition of dendrite arbors and spines in Cornu Ammonis (CA)1 pyramidal neurons and exacerbated behavioral defects. Wnt5a functions cell-autonomously to maintain CA1 dendrites, and exogenous Wnt5a expression corrected structural anomalies even at late-adult stages. These findings reveal a maintenance factor in the adult brain, and highlight a trophic pathway that can be targeted to ameliorate dendrite loss in pathological conditions.
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113
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Lee HJ, Lee JO, Lee YW, Kim SA, Park SH, Kim HS. Kalirin, a GEF for Rac1, plays an important role in FSTL-1-mediated glucose uptake in skeletal muscle cells. Cell Signal 2017; 29:150-157. [DOI: 10.1016/j.cellsig.2016.10.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/27/2016] [Accepted: 10/28/2016] [Indexed: 12/22/2022]
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Human Rho Guanine Nucleotide Exchange Factor 11 (ARHGEF11) Regulates Dendritic Morphogenesis. Int J Mol Sci 2016; 18:ijms18010067. [PMID: 28036092 PMCID: PMC5297702 DOI: 10.3390/ijms18010067] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 12/19/2016] [Accepted: 12/27/2016] [Indexed: 11/17/2022] Open
Abstract
Disturbances of synaptic connectivity during perinatal and adolescent periods have been hypothesized to be related to the pathophysiology of schizophrenia. Rho guanine nucleotide exchange factor 11 (ARHGEF11) is a specific guanine nucleotide exchange factors (GEF) for RhoA, which is a critical regulator of actin cytoskeleton dynamics and organization of dendritic spines and inhibitor of spine maintenance. ARHGEF11 variants are reported to be associated with a higher risk for the onset of schizophrenia in a Japanese population; however, how ARHGEF11 contributes to the pathogenesis of schizophrenia in dendritic spines is unknown. Therefore, we first studied the distribution, binding, and function of ARHGEF11 in the dendritic spines of the rat cerebral cortex. After subcellular fractionation of the rat cerebral cortex, ARHGEF11 was detected with synaptophysin and post-synaptic density protein 95 (PSD-95) in the P2 fractions including synaptosomal fractions containing presynaptic and postsynaptic density proteins. Endogenous ARHGEF11 was coimmunoprecipitated with synaptophysin or PSD-95. In cortical primary neurons at 28 days in vitro, immunostaining revealed that ARHGEF11 located in the dendrites and dendritic spines and colocalized with PSD-95 and synaptophysin. Overexpression of exogenous ARHGEF11 significantly decreased the number of spines (p = 0.008). These results indicate that ARHGEF11 is likely to be associated with synaptic membranes and regulation of spine.
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Abstract
For more than 20 years, we have known that Ca(2+)/calmodulin-dependent protein kinase (CaMKII) activation is both necessary and sufficient for the induction of long-term potentiation (LTP). During this time, tremendous effort has been spent in attempting to understand how CaMKII activation gives rise to this phenomenon. Despite such efforts, there is much to be learned about the molecular mechanisms involved in LTP induction downstream of CaMKII activation. In this review, we highlight recent developments that have shaped our current thinking about the molecular mechanisms underlying LTP and discuss important questions that remain in the field.
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Affiliation(s)
| | - Roger A Nicoll
- Department of Cellular and Molecular Pharmacology and.,Department of Physiology, University of California, San Francisco, California 94143; ,
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116
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The pseudokinase CaMKv is required for the activity-dependent maintenance of dendritic spines. Nat Commun 2016; 7:13282. [PMID: 27796283 PMCID: PMC5095516 DOI: 10.1038/ncomms13282] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 09/19/2016] [Indexed: 02/03/2023] Open
Abstract
Dendritic spine stabilization depends on afferent synaptic input and requires changes in actin cytoskeleton dynamics and protein synthesis. However, the underlying molecular mechanism remains unclear. Here we report the identification of ‘calmodulin kinase-like vesicle-associated' (CaMKv), a pseudokinase of the CaMK family with unknown function, as a synaptic protein crucial for dendritic spine maintenance. CaMKv mRNA localizes at dendrites, and its protein synthesis is regulated by neuronal activity. CaMKv function is inhibited upon phosphorylation by cyclin-dependent kinase 5 (Cdk5) at Thr345. Furthermore, CaMKv knockdown in mouse hippocampal CA1 pyramidal neurons impairs synaptic transmission and plasticity in vivo, resulting in hyperactivity and spatial memory impairment. These findings collectively indicate that the precise regulation of CaMKv through activity-dependent synthesis and post-translational phosphorylation is critical for dendritic spine maintenance, revealing an unusual signalling pathway in the regulation of synaptic transmission and brain function that involves a pseudokinase. CaMKv is a pseduokinase of unknown function. Here, the authors identify the protein as a substrate of the protein kinase Cdk5, and show that CaMKv is synthesized in response to neural activity and plays an important role in maintaining dendritic spines, synaptic plasticity, and hippocampal memory via RhoA inhibition.
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Neuregulin-1 Regulates Cortical Inhibitory Neuron Dendrite and Synapse Growth through DISC1. Neural Plast 2016; 2016:7694385. [PMID: 27847649 PMCID: PMC5099462 DOI: 10.1155/2016/7694385] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 07/05/2016] [Accepted: 09/05/2016] [Indexed: 11/20/2022] Open
Abstract
Cortical inhibitory neurons play crucial roles in regulating excitatory synaptic networks and cognitive function and aberrant development of these cells have been linked to neurodevelopmental disorders. The secreted neurotrophic factor Neuregulin-1 (NRG1) and its receptor ErbB4 are established regulators of inhibitory neuron connectivity, but the developmental signalling mechanisms regulating this process remain poorly understood. Here, we provide evidence that NRG1-ErbB4 signalling functions through the multifunctional scaffold protein, Disrupted in Schizophrenia 1 (DISC1), to regulate the development of cortical inhibitory interneuron dendrite and synaptic growth. We found that NRG1 increases inhibitory neuron dendrite complexity and glutamatergic synapse formation onto inhibitory neurons and that this effect is blocked by expression of a dominant negative DISC1 mutant, or DISC1 knockdown. We also discovered that NRG1 treatment increases DISC1 expression and its localization to glutamatergic synapses being made onto cortical inhibitory neurons. Mechanistically, we determined that DISC1 binds ErbB4 within cortical inhibitory neurons. Collectively, these data suggest that a NRG1-ErbB4-DISC1 signalling pathway regulates the development of cortical inhibitory neuron dendrite and synaptic growth. Given that NRG1, ErbB4, and DISC1 are schizophrenia-linked genes, these findings shed light on how independent risk factors may signal in a common developmental pathway that contributes to neural connectivity defects and disease pathogenesis.
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Actin-Dependent Alterations of Dendritic Spine Morphology in Shankopathies. Neural Plast 2016; 2016:8051861. [PMID: 27795858 PMCID: PMC5067329 DOI: 10.1155/2016/8051861] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 08/30/2016] [Indexed: 12/11/2022] Open
Abstract
Shank proteins (Shank1, Shank2, and Shank3) act as scaffolding molecules in the postsynaptic density of many excitatory neurons. Mutations in SHANK genes, in particular SHANK2 and SHANK3, lead to autism spectrum disorders (ASD) in both human and mouse models. Shank3 proteins are made of several domains-the Shank/ProSAP N-terminal (SPN) domain, ankyrin repeats, SH3 domain, PDZ domain, a proline-rich region, and the sterile alpha motif (SAM) domain. Via various binding partners of these domains, Shank3 is able to bind and interact with a wide range of proteins including modulators of small GTPases such as RICH2, a RhoGAP protein, and βPIX, a RhoGEF protein for Rac1 and Cdc42, actin binding proteins and actin modulators. Dysregulation of all isoforms of Shank proteins, but especially Shank3, leads to alterations in spine morphogenesis, shape, and activity of the synapse via altering actin dynamics. Therefore, here, we highlight the role of Shank proteins as modulators of small GTPases and, ultimately, actin dynamics, as found in multiple in vitro and in vivo models. The failure to mediate this regulatory role might present a shared mechanism in the pathophysiology of autism-associated mutations, which leads to dysregulation of spine morphogenesis and synaptic signaling.
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Grubisha MJ, Lin CW, Tseng GC, Penzes P, Sibille E, Sweet RA. Age-dependent increase in Kalirin-9 and Kalirin-12 transcripts in human orbitofrontal cortex. Eur J Neurosci 2016; 44:2483-2492. [PMID: 27471199 PMCID: PMC5048532 DOI: 10.1111/ejn.13351] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 07/20/2016] [Accepted: 07/22/2016] [Indexed: 12/21/2022]
Abstract
KALRN (KAL) is a Rho GEF that is highly involved in regulation of the actin cytoskeleton within dendrites. There are several isoforms of the protein that arise from differential splicing of KALRN's 66 exons. KAL isoforms have different functions in development. For example, overexpression of the KAL9 and KAL12 isoforms induce dendritic elongation in early development. However, in mature neurons KAL9 overexpression reduces dendritic length, a phenotype also observed in normal human ageing. We therefore hypothesized that KAL9 would have increased expression with age, and undertook to evaluate the expression of individual KALRN exons throughout the adult lifespan. Postmortem human brain grey matter from Brodmann's area (BA) 11 and BA47 derived from a cohort of 209 individuals without psychiatric or neurodegenerative disease, ranging in age from 16 to 91 years, were analysed for KALRN expression by Affymetrix exon array. Analysis of the exon array data in an isoform-specific manner, as well as confirmatory isoform-specific qPCR studies, indicated that the longer KAL9 and KAL12 isoforms demonstrated a statistically significant, but modest, increase with age. The small magnitude of the age effect suggests that inter-individual factors other than age likely contribute to a higher degree to KAL9 and KAL12 expression. In contrast to KAL9 and KAL12, global KALRN expression did not increase with age. Our work suggests that global measures of KALRN gene expression may be misleading and future studies should focus on isoform-specific quantification.
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Affiliation(s)
- Melanie J Grubisha
- Department of Psychiatry, University of Pittsburgh Medical School, Pittsburgh, PA, USA
| | - Chien-Wei Lin
- Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA, USA
| | - George C Tseng
- Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Peter Penzes
- Departments of Physiology and Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Etienne Sibille
- Department of Psychiatry, University of Pittsburgh Medical School, Pittsburgh, PA, USA
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
- Departments of Psychiatry, Pharmacology and Toxicology, Campbell Family Mental Health Research Institute of CAMH, University of Toronto, Toronto, ON, Canada
| | - Robert A Sweet
- Departments of Psychiatry and Neurology, University of Pittsburgh School of Medicine, Biomedical Science Tower, Rm W-1645, 3811 O'Hara Street, Pittsburgh, PA, 15213-2593, USA.
- Mental Illness Research, Education, and Clinical Center, VA Pittsburgh Healthcare System, Pittsburgh, PA, USA.
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120
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Park J, Chávez AE, Mineur YS, Morimoto-Tomita M, Lutzu S, Kim KS, Picciotto MR, Castillo PE, Tomita S. CaMKII Phosphorylation of TARPγ-8 Is a Mediator of LTP and Learning and Memory. Neuron 2016; 92:75-83. [PMID: 27667007 DOI: 10.1016/j.neuron.2016.09.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 06/25/2016] [Accepted: 08/29/2016] [Indexed: 11/28/2022]
Abstract
Protein phosphorylation is an essential step for the expression of long-term potentiation (LTP), a long-lasting, activity-dependent strengthening of synaptic transmission widely regarded as a cellular mechanism underlying learning and memory. At the core of LTP is the synaptic insertion of AMPA receptors (AMPARs) triggered by the NMDA receptor-dependent activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII). However, the CaMKII substrate that increases AMPAR-mediated transmission during LTP remains elusive. Here, we identify the hippocampus-enriched TARPγ-8, but not TARPγ-2/3/4, as a critical CaMKII substrate for LTP. We found that LTP induction increases TARPγ-8 phosphorylation, and that CaMKII-dependent enhancement of AMPAR-mediated transmission requires CaMKII phosphorylation sites of TARPγ-8. Moreover, LTP and memory formation, but not basal transmission, are significantly impaired in mice lacking CaMKII phosphorylation sites of TARPγ-8. Together, these findings demonstrate that TARPγ-8 is a crucial mediator of CaMKII-dependent LTP and therefore a molecular target that controls synaptic plasticity and associated cognitive functions.
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Affiliation(s)
- Joongkyu Park
- Department of Cellular and Molecular Physiology, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Andrés E Chávez
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA; Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Yann S Mineur
- Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Megumi Morimoto-Tomita
- Department of Cellular and Molecular Physiology, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Stefano Lutzu
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Kwang S Kim
- Department of Cellular and Molecular Physiology, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Marina R Picciotto
- Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Pablo E Castillo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Susumu Tomita
- Department of Cellular and Molecular Physiology, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA.
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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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122
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Kim K, Saneyoshi T, Hosokawa T, Okamoto K, Hayashi Y. Interplay of enzymatic and structural functions of CaMKII in long-term potentiation. J Neurochem 2016; 139:959-972. [DOI: 10.1111/jnc.13672] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/09/2016] [Accepted: 05/10/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Karam Kim
- Brain Science Institute; RIKEN; Wako Saitama Japan
| | | | | | - Kenichi Okamoto
- Lunenfeld-Tanenbaum Research Institute; Mount Sinai Hospital; Toronto ON Canada
- Department of Molecular Genetics; Faculty of Medicine; University of Toronto; Toronto ON Canada
| | - Yasunori Hayashi
- Brain Science Institute; RIKEN; Wako Saitama Japan
- Saitama University Brain Science Institute; Saitama University; Saitama Japan
- School of Life Science; South China Normal University; Guangzhou China
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Valdez CM, Murphy GG, Beg AA. The Rac-GAP alpha2-chimaerin regulates hippocampal dendrite and spine morphogenesis. Mol Cell Neurosci 2016; 75:14-26. [PMID: 27297944 DOI: 10.1016/j.mcn.2016.06.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/09/2016] [Accepted: 06/07/2016] [Indexed: 12/01/2022] Open
Abstract
Dendritic spines are fine neuronal processes where spatially restricted input can induce activity-dependent changes in one spine, while leaving neighboring spines unmodified. Morphological spine plasticity is critical for synaptic transmission and is thought to underlie processes like learning and memory. Significantly, defects in dendritic spine stability and morphology are common pathogenic features found in several neurodevelopmental and neuropsychiatric disorders. The remodeling of spines relies on proteins that modulate the underlying cytoskeleton, which is primarily composed of filamentous (F)-actin. The Rho-GTPase Rac1 is a major regulator of F-actin and is essential for the development and plasticity of dendrites and spines. However, the key molecules and mechanisms that regulate Rac1-dependent pathways at spines and synapses are not well understood. We have identified the Rac1-GTPase activating protein, α2-chimaerin, as a critical negative regulator of Rac1 in hippocampal neurons. The loss of α2-chimaerin significantly increases the levels of active Rac1 and induces the formation of aberrant polymorphic dendritic spines. Further, disruption of α2-chimaerin signaling simplifies dendritic arbor complexity and increases the presence of dendritic spines that appear poly-innervated. Our data suggests that α2-chimaerin serves as a "brake" to constrain Rac1-dependent signaling to ensure that the mature morphology of spines is maintained in response to network activity.
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Affiliation(s)
- Chris M Valdez
- Interdepartmental Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, United States
| | - Geoffrey G Murphy
- Interdepartmental Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, United States; Molecular and Behavioral Neuroscience Institute, Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, United States
| | - Asim A Beg
- Interdepartmental Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, United States; Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, United States.
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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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125
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Xu C, Ma XM, Chen HB, Zhou MH, Qiao H, An SC. Orbitofrontal cortex 5-HT2A receptor mediates chronic stress-induced depressive-like behaviors and alterations of spine density and Kalirin7. Neuropharmacology 2016; 109:7-17. [PMID: 26921771 DOI: 10.1016/j.neuropharm.2016.02.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 02/08/2016] [Accepted: 02/15/2016] [Indexed: 12/22/2022]
Abstract
Neuroimaging studies show that patients with major depression have reduced volume of the orbitofrontal cortex (OFC). Although the serotonin (5-HT) 2A receptor, which is abundant in the OFC, has been implicated in depression, the underlying mechanisms in the development of stress-induced depression remain unclear. Kalirin-7 (Kal7) is an essential component of mature excitatory synapses for maintaining dendritic spines density, size and synaptic functions. The aim of this study was to investigate the role of orbitofrontal 5-HT and 5-HT2A receptors in depressive-like behaviors and their associations with Kal7 and dendritic spines using chronic unpredictable mild stress (CUMS), an established animal model of depression. CUMS had no effect on the levels of 5-HT or the 5-HT2A receptor in the OFC. However, CUMS or microinjection of the 5-HT2A/2C receptor agonist (±)-1-(2, 5-Dimethoxy-4-iodophenyl)- 2-aminopropane hydrochloride (DOI, 5 μg/0.5 μL) into the OFC induced depressive-like behaviors, including anhedonia in the sucrose preference test and behavioral despair in the tail suspension test, a significant reduction in body weight gain and locomotor activity in the open field test, which were accompanied by decreased expression of Kal7 and PSD95 as well as decreased density of dendritic spines in the OFC. These alterations induced by CUMS were reversed by pretreatment with the 5-HT2A receptor antagonist Ketanserin (Ket, 5 μg/0.5 μL into the OFC). These results suggest that CUMS alters structural plasticity through activation of the orbital 5-HT2A receptor and is associated with decreased expression of Kal7, thereby resulting in depressive-like behaviors in rats, suggesting an important role of Kal7 in the OFC in depression.
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Affiliation(s)
- Chang Xu
- College of Life Science, Shaanxi Normal University, Xi'an, Shaanxi 710119, China
| | - Xin-Ming Ma
- College of Life Science, Shaanxi Normal University, Xi'an, Shaanxi 710119, China; University of Connecticut Health Center, Department of Neuroscience, Farmington, CT 06030, USA
| | - Hui-Bin Chen
- College of Life Science, Shaanxi Normal University, Xi'an, Shaanxi 710119, China
| | - Meng-He Zhou
- College of Life Science, Shaanxi Normal University, Xi'an, Shaanxi 710119, China
| | - Hui Qiao
- College of Life Science, Shaanxi Normal University, Xi'an, Shaanxi 710119, China
| | - Shu-Cheng An
- College of Life Science, Shaanxi Normal University, Xi'an, Shaanxi 710119, China.
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Control of Dendritic Spine Morphological and Functional Plasticity by Small GTPases. Neural Plast 2016; 2016:3025948. [PMID: 26989514 PMCID: PMC4775798 DOI: 10.1155/2016/3025948] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 01/06/2016] [Accepted: 01/19/2016] [Indexed: 11/18/2022] Open
Abstract
Structural plasticity of excitatory synapses is a vital component of neuronal development, synaptic plasticity, and behaviour. Abnormal development or regulation of excitatory synapses has also been strongly implicated in many neurodevelopmental, psychiatric, and neurodegenerative disorders. In the mammalian forebrain, the majority of excitatory synapses are located on dendritic spines, specialized dendritic protrusions that are enriched in actin. Research over recent years has begun to unravel the complexities involved in the regulation of dendritic spine structure. The small GTPase family of proteins have emerged as key regulators of structural plasticity, linking extracellular signals with the modulation of dendritic spines, which potentially underlies their ability to influence cognition. Here we review a number of studies that examine how small GTPases are activated and regulated in neurons and furthermore how they can impact actin dynamics, and thus dendritic spine morphology. Elucidating this signalling process is critical for furthering our understanding of the basic mechanisms by which information is encoded in neural circuits but may also provide insight into novel targets for the development of effective therapies to treat cognitive dysfunction seen in a range of neurological disorders.
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127
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Kalirin and Trio proteins serve critical roles in excitatory synaptic transmission and LTP. Proc Natl Acad Sci U S A 2016; 113:2264-9. [PMID: 26858404 DOI: 10.1073/pnas.1600179113] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The molecular mechanism underlying long-term potentiation (LTP) is critical for understanding learning and memory. CaMKII, a key kinase involved in LTP, is both necessary and sufficient for LTP induction. However, how CaMKII gives rise to LTP is currently unknown. Recent studies suggest that Rho GTPases are necessary for LTP. Rho GTPases are activated by Rho guanine exchange factors (RhoGEFs), but the RhoGEF(s) required for LTP also remain unknown. Here, using a combination of molecular, electrophysiological, and imaging techniques, we show that the RhoGEF Kalirin and its paralog Trio play critical and redundant roles in excitatory synapse structure and function. Furthermore, we show that CaMKII phosphorylation of Kalirin is sufficient to enhance synaptic AMPA receptor expression, and that preventing CaMKII signaling through Kalirin and Trio prevents LTP induction. Thus, our data identify Kalirin and Trio as the elusive targets of CaMKII phosphorylation responsible for AMPA receptor up-regulation during LTP.
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128
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Ba W, Yan Y, Reijnders MRF, Schuurs-Hoeijmakers JHM, Feenstra I, Bongers EMHF, Bosch DGM, De Leeuw N, Pfundt R, Gilissen C, De Vries PF, Veltman JA, Hoischen A, Mefford HC, Eichler EE, Vissers LELM, Nadif Kasri N, De Vries BBA. TRIO loss of function is associated with mild intellectual disability and affects dendritic branching and synapse function. Hum Mol Genet 2015; 25:892-902. [PMID: 26721934 DOI: 10.1093/hmg/ddv618] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 12/18/2015] [Indexed: 12/21/2022] Open
Abstract
Recently, we marked TRIO for the first time as a candidate gene for intellectual disability (ID). Across diverse vertebrate species, TRIO is a well-conserved Rho GTPase regulator that is highly expressed in the developing brain. However, little is known about the specific events regulated by TRIO during brain development and its clinical impact in humans when mutated. Routine clinical diagnostic testing identified an intragenic de novo deletion of TRIO in a boy with ID. Targeted sequencing of this gene in over 2300 individuals with ID, identified three additional truncating mutations. All index cases had mild to borderline ID combined with behavioral problems consisting of autistic, hyperactive and/or aggressive behavior. Studies in dissociated rat hippocampal neurons demonstrated the enhancement of dendritic formation by suppressing endogenous TRIO, and similarly decreasing endogenous TRIO in organotypic hippocampal brain slices significantly increased synaptic strength by increasing functional synapses. Together, our findings provide new mechanistic insight into how genetic deficits in TRIO can lead to early neuronal network formation by directly affecting both neurite outgrowth and synapse development.
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Affiliation(s)
- Wei Ba
- Department of Human Genetics, Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Yan Yan
- Department of Neuroscience, UCONN Health Center, Farmington, CT 06030, USA
| | | | | | | | | | - Daniëlle G M Bosch
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands, Bartiméus, Institute for the Visually Impaired, Zeist, The Netherlands and
| | | | | | | | | | - Joris A Veltman
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands, Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | | | - Heather C Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - Evan E Eichler
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA 98195, USA, Howard Hughes Medical Institute, Seattle, WA 98195, USA
| | | | - Nael Nadif Kasri
- Department of Human Genetics, Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands,
| | - Bert B A De Vries
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands,
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Emerging Roles of Filopodia and Dendritic Spines in Motoneuron Plasticity during Development and Disease. Neural Plast 2015; 2016:3423267. [PMID: 26843990 PMCID: PMC4710938 DOI: 10.1155/2016/3423267] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 09/10/2015] [Accepted: 09/21/2015] [Indexed: 01/16/2023] Open
Abstract
Motoneurons develop extensive dendritic trees for receiving excitatory and inhibitory synaptic inputs to perform a variety of complex motor tasks. At birth, the somatodendritic domains of mouse hypoglossal and lumbar motoneurons have dense filopodia and spines. Consistent with Vaughn's synaptotropic hypothesis, we propose a developmental unified-hybrid model implicating filopodia in motoneuron spinogenesis/synaptogenesis and dendritic growth and branching critical for circuit formation and synaptic plasticity at embryonic/prenatal/neonatal period. Filopodia density decreases and spine density initially increases until postnatal day 15 (P15) and then decreases by P30. Spine distribution shifts towards the distal dendrites, and spines become shorter (stubby), coinciding with decreases in frequency and increases in amplitude of excitatory postsynaptic currents with maturation. In transgenic mice, either overexpressing the mutated human Cu/Zn-superoxide dismutase (hSOD1G93A) gene or deficient in GABAergic/glycinergic synaptic transmission (gephyrin, GAD-67, or VGAT gene knockout), hypoglossal motoneurons develop excitatory glutamatergic synaptic hyperactivity. Functional synaptic hyperactivity is associated with increased dendritic growth, branching, and increased spine and filopodia density, involving actin-based cytoskeletal and structural remodelling. Energy-dependent ionic pumps that maintain intracellular sodium/calcium homeostasis are chronically challenged by activity and selectively overwhelmed by hyperactivity which eventually causes sustained membrane depolarization leading to excitotoxicity, activating microglia to phagocytose degenerating neurons under neuropathological conditions.
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Puigdellívol M, Cherubini M, Brito V, Giralt A, Suelves N, Ballesteros J, Zamora-Moratalla A, Martín ED, Eipper BA, Alberch J, Ginés S. A role for Kalirin-7 in corticostriatal synaptic dysfunction in Huntington's disease. Hum Mol Genet 2015; 24:7265-85. [PMID: 26464483 DOI: 10.1093/hmg/ddv426] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 10/05/2015] [Indexed: 01/09/2023] Open
Abstract
Cognitive dysfunction is an early clinical hallmark of Huntington's disease (HD) preceding the appearance of motor symptoms by several years. Neuronal dysfunction and altered corticostriatal connectivity have been postulated to be fundamental to explain these early disturbances. However, no treatments to attenuate cognitive changes have been successful: the reason may rely on the idea that the temporal sequence of pathological changes is as critical as the changes per se when new therapies are in development. To this aim, it becomes critical to use HD mouse models in which cognitive impairments appear prior to motor symptoms. In this study, we demonstrate procedural memory and motor learning deficits in two different HD mice and at ages preceding motor disturbances. These impairments are associated with altered corticostriatal long-term potentiation (LTP) and specific reduction of dendritic spine density and postsynaptic density (PSD)-95 and spinophilin-positive clusters in the cortex of HD mice. As a potential mechanism, we described an early decrease of Kalirin-7 (Kal7), a guanine-nucleotide exchange factor for Rho-like small GTPases critical to maintain excitatory synapse, in the cortex of HD mice. Supporting a role for Kal7 in HD synaptic deficits, exogenous expression of Kal7 restores the reduction of excitatory synapses in HD cortical cultures. Altogether, our results suggest that cortical dysfunction precedes striatal disturbances in HD and underlie early corticostriatal LTP and cognitive defects. Moreover, we identified diminished Kal7 as a key contributor to HD cortical alterations, placing Kal7 as a molecular target for future therapies aimed to restore corticostriatal function in HD.
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Affiliation(s)
- Mar Puigdellívol
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain, CIBERNED, Madrid, Spain
| | - Marta Cherubini
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain, CIBERNED, Madrid, Spain
| | - Verónica Brito
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain, CIBERNED, Madrid, Spain
| | - Albert Giralt
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain, CIBERNED, Madrid, Spain
| | - Núria Suelves
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain, CIBERNED, Madrid, Spain
| | - Jesús Ballesteros
- Laboratory of Neurophysiology and Synaptic Plasticity, Albacete Science and Technology Park (PCYTA), Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain and
| | - Alfonsa Zamora-Moratalla
- Laboratory of Neurophysiology and Synaptic Plasticity, Albacete Science and Technology Park (PCYTA), Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain and
| | - Eduardo D Martín
- Laboratory of Neurophysiology and Synaptic Plasticity, Albacete Science and Technology Park (PCYTA), Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain and
| | - Betty A Eipper
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA
| | - Jordi Alberch
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain, CIBERNED, Madrid, Spain
| | - Silvia Ginés
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain, CIBERNED, Madrid, Spain,
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131
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Woolfrey KM, Dell'Acqua ML. Coordination of Protein Phosphorylation and Dephosphorylation in Synaptic Plasticity. J Biol Chem 2015; 290:28604-12. [PMID: 26453308 DOI: 10.1074/jbc.r115.657262] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A central theme in nervous system function is equilibrium: synaptic strengths wax and wane, neuronal firing rates adjust up and down, and neural circuits balance excitation with inhibition. This push/pull regulatory theme carries through to the molecular level at excitatory synapses, where protein function is controlled through phosphorylation and dephosphorylation by kinases and phosphatases. However, these opposing enzymatic activities are only part of the equation as scaffolding interactions and assembly of multi-protein complexes are further required for efficient, localized synaptic signaling. This review will focus on coordination of postsynaptic serine/threonine kinase and phosphatase signaling by scaffold proteins during synaptic plasticity.
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Affiliation(s)
- Kevin M Woolfrey
- From the Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado 80045
| | - Mark L Dell'Acqua
- From the Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado 80045
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132
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Viggiano D, Srivastava DP, Speranza L, Perrone-Capano C, Bellenchi GC, di Porzio U, Buckley NJ. Quantifying barcodes of dendritic spines using entropy-based metrics. Sci Rep 2015; 5:14622. [PMID: 26419702 PMCID: PMC4588562 DOI: 10.1038/srep14622] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/18/2015] [Indexed: 11/09/2022] Open
Abstract
Spine motility analysis has become the mainstay for investigating synaptic plasticity but is limited in its versatility requiring complex, non automatized instrumentations. We describe an entropy-based method for determining the spatial distribution of dendritic spines that allows successful estimation of spine motility from still images. This method has the potential to extend the applicability of spine motility analysis to ex vivo preparations.
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Affiliation(s)
- D Viggiano
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, 80131, Italy.,Department of Medicine and Health Sciences, Univ. Molise, Campobasso, 86100, Italy
| | - D P Srivastava
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, SE5 8AF, United Kingdom.,Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - L Speranza
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, 80131, Italy
| | - C Perrone-Capano
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, 80131, Italy.,Department of Pharmacy, University of Naples "Federico II", Naples, 80131, Italy
| | - G C Bellenchi
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, 80131, Italy
| | - U di Porzio
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, 80131, Italy
| | - N J Buckley
- Department of Psychiatry, University of Oxford, Oxford, OX3 7JX, United Kingdom
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133
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Differential CaMKII regulation by voltage-gated calcium channels in the striatum. Mol Cell Neurosci 2015; 68:234-43. [PMID: 26255006 DOI: 10.1016/j.mcn.2015.08.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 07/06/2015] [Accepted: 08/03/2015] [Indexed: 01/21/2023] Open
Abstract
Calcium signaling regulates synaptic plasticity and many other functions in striatal medium spiny neurons to modulate basal ganglia function. Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is a major calcium-dependent signaling protein that couples calcium entry to diverse cellular changes. CaMKII activation results in autophosphorylation at Thr286 and sustained calcium-independent CaMKII activity after calcium signals dissipate. However, little is known about the mechanisms regulating striatal CaMKII. To address this, mouse brain slices were treated with pharmacological modulators of calcium channels and punches of dorsal striatum were immunoblotted for CaMKII Thr286 autophosphorylation as an index of CaMKII activation. KCl depolarization increased levels of CaMKII autophosphorylation ~2-fold; this increase was blocked by an LTCC antagonist and was mimicked by treatment with pharmacological LTCC activators. The chelation of extracellular calcium robustly decreased basal CaMKII autophosphorylation within 5min and increased levels of total CaMKII in cytosolic fractions, in addition to decreasing the phosphorylation of CaMKII sites in the GluN2B subunit of NMDA receptors and the GluA1 subunit of AMPA receptors. We also found that the maintenance of basal levels of CaMKII autophosphorylation requires low-voltage gated T-type calcium channels, but not LTCCs or R-type calcium channels. Our findings indicate that CaMKII activity is dynamically regulated by multiple calcium channels in the striatum thus coupling calcium entry to key downstream substrates.
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134
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Duman JG, Mulherkar S, Tu YK, X Cheng J, Tolias KF. Mechanisms for spatiotemporal regulation of Rho-GTPase signaling at synapses. Neurosci Lett 2015; 601:4-10. [PMID: 26003445 DOI: 10.1016/j.neulet.2015.05.034] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 05/16/2015] [Accepted: 05/18/2015] [Indexed: 01/16/2023]
Abstract
Synapses mediate information flow between neurons and undergo plastic changes in response to experience, which is critical for learning and memory. Conversely, synaptic defects impair information processing and underlie many brain pathologies. Rho-family GTPases control synaptogenesis by transducing signals from extracellular stimuli to the cytoskeleton and nucleus. The Rho-GTPases Rac1 and Cdc42 promote synapse development and the growth of axons and dendrites, while RhoA antagonizes these processes. Despite its importance, many aspects of Rho-GTPase signaling remain relatively unknown. Rho-GTPases are activated by guanine nucleotide exchange factors (GEFs) and inhibited by GTPase-activating proteins (GAPs). Though the number of both GEFs and GAPs greatly exceeds that of Rho-GTPases, loss of even a single GEF or GAP often has profound effects on cognition and behavior. Here, we explore how the actions of specific GEFs and GAPs give rise to the precise spatiotemporal activation patterns of Rho-GTPases in neurons. We consider the effects of coupling GEFs and GAPs targeting the same Rho-GTPase and the modular pathways that connect specific cellular stimuli with a given Rho-GTPase via different GEFs. We discuss how the creation of sharp borders between Rho-GTPase activation zones is achieved by pairing a GEF for one Rho-GTPase with a GAP for another and the extensive crosstalk between different Rho-GTPases. Given the importance of synapses for cognition and the fundamental roles that Rho-GTPases play in regulating them, a detailed understanding of Rho-GTPase signaling is essential to the progress of neuroscience.
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Affiliation(s)
- Joseph G Duman
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Yen-Kuei Tu
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Integrative Molecular and Biomedical Sciences Program,Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Jinxuan X Cheng
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Kimberley F Tolias
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Integrative Molecular and Biomedical Sciences Program,Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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135
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Neurexin-Neuroligin Synaptic Complex Regulates Schizophrenia-Related DISC1/Kal-7/Rac1 "Signalosome". Neural Plast 2015; 2015:167308. [PMID: 26078884 PMCID: PMC4452847 DOI: 10.1155/2015/167308] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 05/04/2015] [Indexed: 12/22/2022] Open
Abstract
Neurexins (NXs) and neuroligins (NLs) are cell adhesion molecules that are localized at opposite sites of synaptic membranes. They interact with each other to promote the assembly, maintenance, and function of synapses in the central nervous system. Both NX and NL are cleaved from a membrane-attached intracellular domain in an activity-dependent manner, generating the soluble ectodomain of NX or NL. Expression of the NX1 and NX3 genes in the brain appears to be regulated by a schizophrenia-related protein, DISC1. Here, we show that soluble ecto-NX1β can regulate the expression of DISC1 and induce signaling downstream of DISC1. We also show that NL1 binds to a well-characterized DISC1 interaction partner, Kal-7, and this interaction can be compromised by DISC1. Our results indicate that the NX/NL synaptic complex is intrinsically involved in the regulation of DISC1 function, thus contributing to a better understanding of the pathology of schizophrenia.
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136
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Araki Y, Zeng M, Zhang M, Huganir RL. Rapid dispersion of SynGAP from synaptic spines triggers AMPA receptor insertion and spine enlargement during LTP. Neuron 2015; 85:173-189. [PMID: 25569349 DOI: 10.1016/j.neuron.2014.12.023] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2014] [Indexed: 10/24/2022]
Abstract
SynGAP is a Ras-GTPase activating protein highly enriched at excitatory synapses in the brain. Previous studies have shown that CaMKII and the RAS-ERK pathway are critical for several forms of synaptic plasticity including LTP. NMDA receptor-dependent calcium influx has been shown to regulate the RAS-ERK pathway and downstream events that result in AMPA receptor synaptic accumulation, spine enlargement, and synaptic strengthening during LTP. However, the cellular mechanisms whereby calcium influx and CaMKII control Ras activity remain elusive. Using live-imaging techniques, we have found that SynGAP is rapidly dispersed from spines upon LTP induction in hippocampal neurons, and this dispersion depends on phosphorylation of SynGAP by CaMKII. Moreover, the degree of acute dispersion predicts the maintenance of spine enlargement. Thus, the synaptic dispersion of SynGAP by CaMKII phosphorylation during LTP represents a key signaling component that transduces CaMKII activity to small G protein-mediated spine enlargement, AMPA receptor synaptic incorporation, and synaptic potentiation.
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Affiliation(s)
- Yoichi Araki
- Department of Neuroscience and Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Menglong Zeng
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Mingjie Zhang
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Richard L Huganir
- Department of Neuroscience and Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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137
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Sellers KJ, Erli F, Raval P, Watson IA, Chen D, Srivastava DP. Rapid modulation of synaptogenesis and spinogenesis by 17β-estradiol in primary cortical neurons. Front Cell Neurosci 2015; 9:137. [PMID: 25926772 PMCID: PMC4396386 DOI: 10.3389/fncel.2015.00137] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 03/23/2015] [Indexed: 01/06/2023] Open
Abstract
In the mammalian forebrain, the majority of excitatory synapses occur on dendritic spines. Changes in the number of these structures is important for brain development, plasticity and the refinement of neuronal circuits. The formation of excitatory synapses involves the coordinated formation of dendritic spines and targeting of multi-protein complexes to nascent connections. Recent studies have demonstrated that the estrogen 17β-estradiol (E2) can rapidly increase the number of dendritic spines, an effect consistent with the ability of E2 to rapidly influence cognitive function. However, the molecular composition of E2-induced spines and whether these protrusions form synaptic connections has not been fully elucidated. Moreover, which estrogen receptor(s) (ER) mediate these spine-morphogenic responses are not clear. Here, we report that acute E2 treatment results in the recruitment of postsynaptic density protein 95 (PSD-95) to novel dendritic spines. In addition neuroligin 1 (Nlg-1) and the NMDA receptor subunit GluN1 are recruited to nascent synapses in cortical neurons. The presence of these synaptic proteins at nascent synapses suggests that the machinery to allow pre- and post-synapses to form connections are present in E2-induced spines. We further demonstrate that E2 treatment results in the rapid and transient activation of extracellular signal-regulated kinase 1/2 (ERK1/2), Akt and the mammalian target of rapamycin (mTOR) signaling pathways. However, only ERK1/2 and Akt are required for E2-mediated spinogenesis. Using synthetic receptor modulators, we further demonstrate that activation of the estrogen receptor beta (ERβ) but not alpha (ERα) mimics rapid E2-induced spinogenesis and synaptogenesis. Taken together these findings suggest that in primary cortical neurons, E2 signaling via ERβ, but not through ERα, is capable of remodeling neuronal circuits by increasing the number of excitatory synapses.
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Affiliation(s)
- Katherine J Sellers
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London London, UK
| | - Filippo Erli
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London London, UK ; Department of Biotechnology and Biosciences, Univeristy of Milano-Bicocca Milano, Italy
| | - Pooja Raval
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London London, UK
| | - Iain A Watson
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London London, UK
| | - Ding Chen
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London London, UK
| | - Deepak P Srivastava
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London London, UK
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138
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A role for Kalirin-7 in nociceptive sensitization via activity-dependent modulation of spinal synapses. Nat Commun 2015; 6:6820. [PMID: 25865668 PMCID: PMC4403379 DOI: 10.1038/ncomms7820] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/03/2015] [Indexed: 12/20/2022] Open
Abstract
Synaptic plasticity is the cornerstone of processes underlying persistent nociceptive activity-induced changes in normal nociceptive sensitivity. Kalirin-7 is a multifunctional guanine-nucleotide-exchange factor (GEF) for Rho GTPases that is characterized by its localization at excitatory synapses, interactions with glutamate receptors and its ability to dynamically modulate the neuronal cytoskeleton. Here we show that spinally expressed Kalirin-7 is required for persistent nociceptive activity-dependent synaptic long-term potentiation as well as activity-dependent remodelling of synaptic spines in the spinal dorsal horn, thereby orchestrating functional and structural plasticity during the course of inflammatory pain.
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139
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Miller MB, Vishwanatha KS, Mains RE, Eipper BA. An N-terminal Amphipathic Helix Binds Phosphoinositides and Enhances Kalirin Sec14 Domain-mediated Membrane Interactions. J Biol Chem 2015; 290:13541-55. [PMID: 25861993 DOI: 10.1074/jbc.m115.636746] [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: 01/06/2015] [Indexed: 11/06/2022] Open
Abstract
Previous studies revealed an essential role for the lipid-binding Sec14 domain of kalirin (KalSec14), but its mechanism of action is not well understood. Because alternative promoter usage appends unique N-terminal peptides to the KalSec14 domain, we used biophysical, biochemical, and cell biological approaches to examine the two major products, bKalSec14 and cKalSec14. Promoter B encodes a charged, unstructured peptide, whereas promoter C encodes an amphipathic helix (Kal-C-helix). Both bKalSec14 and cKalSec14 interacted with lipids in PIP strip and liposome flotation assays, with significantly greater binding by cKalSec14 in both assays. Disruption of the hydrophobic face of the Kal-C-helix in cKalSec14KKED eliminated its increased liposome binding. Although cKalSec14 showed significantly reduced binding to liposomes lacking phosphatidylinositol phosphates or cholesterol, liposome binding by bKalSec14 and cKalSec14KKED was not affected. When expressed in AtT-20 cells, bKalSec14-GFP was diffusely localized, whereas cKalSec14-GFP localized to the trans-Golgi network and secretory granules. The amphipathic C-helix was sufficient for this localization. When AtT-20 cells were treated with a cell-permeant derivative of the Kal-C-helix (Kal-C-helix-Arg9), we observed increased secretion of a product stored in mature secretory granules, with no effect on basal secretion; a cell-permeant control peptide (Kal-C-helixKKED-Arg9) did not have this effect. Through its ability to control expression of a novel, phosphoinositide-binding amphipathic helix, Kalrn promoter usage is expected to affect function.
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Affiliation(s)
| | | | | | - Betty A Eipper
- From the Departments of Neuroscience and Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut 06030
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140
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Regulating Rac in the nervous system: molecular function and disease implication of Rac GEFs and GAPs. BIOMED RESEARCH INTERNATIONAL 2015; 2015:632450. [PMID: 25879033 PMCID: PMC4388020 DOI: 10.1155/2015/632450] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/06/2015] [Indexed: 12/11/2022]
Abstract
Rho family GTPases, including RhoA, Rac1, and Cdc42 as the most studied members, are master regulators of actin cytoskeletal organization. Rho GTPases control various aspects of the nervous system and are associated with a number of neuropsychiatric and neurodegenerative diseases. The activity of Rho GTPases is controlled by two families of regulators, guanine nucleotide exchange factors (GEFs) as the activators and GTPase-activating proteins (GAPs) as the inhibitors. Through coordinated regulation by GEFs and GAPs, Rho GTPases act as converging signaling molecules that convey different upstream signals in the nervous system. So far, more than 70 members of either GEFs or GAPs of Rho GTPases have been identified in mammals, but only a small subset of them have well-known functions. Thus, characterization of important GEFs and GAPs in the nervous system is crucial for the understanding of spatiotemporal dynamics of Rho GTPase activity in different neuronal functions. In this review, we summarize the current understanding of GEFs and GAPs for Rac1, with emphasis on the molecular function and disease implication of these regulators in the nervous system.
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141
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Evans JC, Robinson CM, Shi M, Webb DJ. The guanine nucleotide exchange factor (GEF) Asef2 promotes dendritic spine formation via Rac activation and spinophilin-dependent targeting. J Biol Chem 2015; 290:10295-308. [PMID: 25750125 DOI: 10.1074/jbc.m114.605543] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Indexed: 11/06/2022] Open
Abstract
Dendritic spines are actin-rich protrusions that establish excitatory synaptic contacts with surrounding neurons. Reorganization of the actin cytoskeleton is critical for the development and plasticity of dendritic spines, which is the basis for learning and memory. Rho family GTPases are emerging as important modulators of spines and synapses, predominantly through their ability to regulate actin dynamics. Much less is known, however, about the function of guanine nucleotide exchange factors (GEFs), which activate these GTPases, in spine and synapse development. In this study we show that the Rho family GEF Asef2 is found at synaptic sites, where it promotes dendritic spine and synapse formation. Knockdown of endogenous Asef2 with shRNAs impairs spine and synapse formation, whereas exogenous expression of Asef2 causes an increase in spine and synapse density. This effect of Asef2 on spines and synapses is abrogated by expression of GEF activity-deficient Asef2 mutants or by knockdown of Rac, suggesting that Asef2-Rac signaling mediates spine development. Because Asef2 interacts with the F-actin-binding protein spinophilin, which localizes to spines, we investigated the role of spinophilin in Asef2-promoted spine formation. Spinophilin recruits Asef2 to spines, and knockdown of spinophilin hinders spine and synapse formation in Asef2-expressing neurons. Furthermore, inhibition of N-methyl-d-aspartate receptor (NMDA) activity blocks spinophilin-mediated localization of Asef2 to spines. These results collectively point to spinophilin-Asef2-Rac signaling as a novel mechanism for the development of dendritic spines and synapses.
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Affiliation(s)
- J Corey Evans
- From the Department of Biological Sciences and the Kennedy Center for Research on Human Development and
| | - Cristina M Robinson
- From the Department of Biological Sciences and the Kennedy Center for Research on Human Development and
| | - Mingjian Shi
- From the Department of Biological Sciences and the Kennedy Center for Research on Human Development and
| | - Donna J Webb
- From the Department of Biological Sciences and the Kennedy Center for Research on Human Development and the Department of Cancer Biology, Vanderbilt University, Nashville, Tennessee 37235
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142
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Li J, Zhang L, Chen Z, Xie M, Huang L, Xue J, Liu Y, Liu N, Guo F, Zheng Y, Kong J, Zhang L, Zhang L. Cocaine activates Rac1 to control structural and behavioral plasticity in caudate putamen. Neurobiol Dis 2015; 75:159-76. [PMID: 25595128 DOI: 10.1016/j.nbd.2014.12.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 11/19/2014] [Accepted: 12/18/2014] [Indexed: 12/24/2022] Open
Abstract
Repeated exposure to cocaine was previously found to cause sensitized behavioral responses and structural remodeling on medium spiny neurons of the nucleus accumbens (NAc) and caudate putamen (CPu). Rac1 has emerged as a key integrator of environmental cues that regulates dendritic cytoskeletons. In this study, we investigated the role of Rac1 in cocaine-induced dendritic and behavioral plasticity in the CPu. We found that Rac1 activation was reduced in the NAc but increased in the CPu following repeated cocaine treatment. Inhibition of Rac1 activity by a Rac1-specific inhibitor NSC23766, overexpression of a dominant negative mutant of Rac1 (T17N-Rac1) or local knockout of Rac1 attenuated the cocaine-induced increase in dendrites and spine density in the CPu, whereas overexpression of a constitutively active Rac1 exert the opposite effect. Moreover, NSC23766 reversed the increased number of asymmetric spine synapses in the CPu following chronic cocaine exposure. Downregulation of Rac1 activity likewise attenuates behavioral reward responses to cocaine exposure, with activation of Rac1 producing the opposite effect. Thus, Rac1 signaling is differentially regulated in the NAc and CPu after repeated cocaine treatment, and induction of Rac1 activation in the CPu is important for cocaine exposure-induced dendritic remodeling and behavioral plasticity.
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Affiliation(s)
- Juan Li
- Key Laboratory of Functional Proteomics of Guangdong Province, Department of Pathophysiology, Southern Medical University, Guangzhou 510515, China; Department of Histology and Embryology, Southern Medical University, Guangzhou 510515, China
| | - Lei Zhang
- Department of Histology and Embryology, Southern Medical University, Guangzhou 510515, China
| | - Zhenzhong Chen
- Key Laboratory of Functional Proteomics of Guangdong Province, Department of Pathophysiology, Southern Medical University, Guangzhou 510515, China
| | - Minjuan Xie
- Key Laboratory of Functional Proteomics of Guangdong Province, Department of Pathophysiology, Southern Medical University, Guangzhou 510515, China
| | - Lu Huang
- Key Laboratory of Functional Proteomics of Guangdong Province, Department of Pathophysiology, Southern Medical University, Guangzhou 510515, China
| | - Jinhua Xue
- Key Laboratory of Functional Proteomics of Guangdong Province, Department of Pathophysiology, Southern Medical University, Guangzhou 510515, China
| | - Yutong Liu
- Key Laboratory of Functional Proteomics of Guangdong Province, Department of Pathophysiology, Southern Medical University, Guangzhou 510515, China
| | - Nuyun Liu
- Elderly Health Services Research Center, Southern Medical University, Guangzhou 510515, China
| | - Fukun Guo
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Research Foundation, Cincinnati, OH, USA
| | - Yi Zheng
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Research Foundation, Cincinnati, OH, USA
| | - Jiming Kong
- Southern Medical University-University of Manitoba Geriatric Medicine Joint Laboratory, Guangzhou 510515, China
| | - Lin Zhang
- Department of Histology and Embryology, Southern Medical University, Guangzhou 510515, China.
| | - Lu Zhang
- Key Laboratory of Functional Proteomics of Guangdong Province, Department of Pathophysiology, Southern Medical University, Guangzhou 510515, China; Elderly Health Services Research Center, Southern Medical University, Guangzhou 510515, China; Southern Medical University-University of Manitoba Geriatric Medicine Joint Laboratory, Guangzhou 510515, China.
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143
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Vogl AM, Brockmann MM, Giusti SA, Maccarrone G, Vercelli CA, Bauder CA, Richter JS, Roselli F, Hafner AS, Dedic N, Wotjak CT, Vogt-Weisenhorn DM, Choquet D, Turck CW, Stein V, Deussing JM, Refojo D. Neddylation inhibition impairs spine development, destabilizes synapses and deteriorates cognition. Nat Neurosci 2015; 18:239-51. [PMID: 25581363 DOI: 10.1038/nn.3912] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Accepted: 12/04/2014] [Indexed: 02/08/2023]
Abstract
Neddylation is a ubiquitylation-like pathway that controls cell cycle and proliferation by covalently conjugating Nedd8 to specific targets. However, its role in neurons, nonreplicating postmitotic cells, remains unexplored. Here we report that Nedd8 conjugation increased during postnatal brain development and is active in mature synapses, where many proteins are neddylated. We show that neddylation controls spine development during neuronal maturation and spine stability in mature neurons. We found that neddylated PSD-95 was present in spines and that neddylation on Lys202 of PSD-95 is required for the proactive role of the scaffolding protein in spine maturation and synaptic transmission. Finally, we developed Nae1(CamKIIα-CreERT2) mice, in which neddylation is conditionally ablated in adult excitatory forebrain neurons. These mice showed synaptic loss, impaired neurotransmission and severe cognitive deficits. In summary, our results establish neddylation as an active post-translational modification in the synapse regulating the maturation, stability and function of dendritic spines.
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Affiliation(s)
- Annette M Vogl
- Molecular Neurobiology, Max Planck Institute of Psychiatry, Munich, Germany
| | - Marisa M Brockmann
- Molecular Neurobiology, Max Planck Institute of Psychiatry, Munich, Germany
| | - Sebastian A Giusti
- Molecular Neurobiology, Max Planck Institute of Psychiatry, Munich, Germany
| | - Giuseppina Maccarrone
- Department for Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany
| | - Claudia A Vercelli
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET-Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| | - Corinna A Bauder
- Molecular Neurobiology, Max Planck Institute of Psychiatry, Munich, Germany
| | - Julia S Richter
- Molecular Neurobiology, Max Planck Institute of Psychiatry, Munich, Germany
| | - Francesco Roselli
- 1] Department of Neurobiology of Stress and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany. [2] Department of Neuroscience, Section of Neurology, University of Bari, Bari, Italy
| | - Anne-Sophie Hafner
- 1] University of Bordeaux, Interdisciplinary Institute for Neuroscience, Bordeaux, France. [2] CNRS UMR 5297, Bordeaux, France
| | - Nina Dedic
- 1] Department of Neurobiology of Stress and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany. [2] Institute of Developmental Genetics, Helmholtz-Zentrum München, Neuherberg, Germany
| | - Carsten T Wotjak
- Department of Neurobiology of Stress and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | | | - Daniel Choquet
- 1] University of Bordeaux, Interdisciplinary Institute for Neuroscience, Bordeaux, France. [2] CNRS UMR 5297, Bordeaux, France
| | - Christoph W Turck
- Department for Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany
| | - Valentin Stein
- Institute of Physiology, University of Bonn, Bonn, Germany
| | - Jan M Deussing
- Department of Neurobiology of Stress and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Damian Refojo
- Molecular Neurobiology, Max Planck Institute of Psychiatry, Munich, Germany
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144
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Lefort R. Reversing synapse loss in Alzheimer's disease: Rho-guanosine triphosphatases and insights from other brain disorders. Neurotherapeutics 2015; 12:19-28. [PMID: 25588580 PMCID: PMC4322073 DOI: 10.1007/s13311-014-0328-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Alzheimer's disease (AD) is a monumental public health crisis with no effective cure or treatment. To date, therapeutic strategies have focused almost exclusively on upstream signaling events in the disease, namely on β-amyloid and amyloid precursor protein processing, and have, unfortunately, yielded few, if any, promising results. An alternative approach may be to target signaling events downstream of β-amyloid and even tau. However, with so many pathways already linked to the disease, understanding which ones are "drivers" versus "passengers" in the pathogenesis of the disease remains a tremendous challenge. Given the critical roles of Rho-guanosine triphosphatases (GTPases) in regulating the actin cytoskeleton and spine dynamics, and the strong association between spine abnormalities and cognition, it is not surprising that mutations in a number of genes involved in Rho-GTPase signaling have been implicated in several brain disorders, including schizophrenia and autism. And now, there is mounting literature implicating Rho-GTPase signaling in AD pathogenesis as well. Here, I review this evidence, with a particular emphasis on the regulators of Rho-GTPase signaling, namely guanine nucleotide exchange factors and GTPase-activating proteins. Several of these have been linked to various aspects of AD, and each offers a novel potential therapeutic target for AD.
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Affiliation(s)
- Roger Lefort
- The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, and Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, 10032, USA,
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145
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Sellers K, Raval P, Srivastava DP. Molecular signature of rapid estrogen regulation of synaptic connectivity and cognition. Front Neuroendocrinol 2015; 36:72-89. [PMID: 25159586 DOI: 10.1016/j.yfrne.2014.08.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 08/11/2014] [Accepted: 08/14/2014] [Indexed: 12/14/2022]
Abstract
There is now a growing appreciation that estrogens are capable of rapidly activating a number of signaling cascades within the central nervous system. In addition, there are an increasing number of studies reporting that 17β-estradiol, the major biologically active estrogen, can modulate cognition within a rapid time frame. Here we review recent studies that have begun to uncover the molecular and cellular framework which contributes to estrogens ability to rapidly modulate cognition. We first describe the mechanisms by which estrogen receptors (ERs) can couple to intracellular signaling cascades, either directly, or via the transactivation of other receptors. Subsequently, we review the evidence that estrogen can rapidly modulate both neuronal function and structure in the hippocampus and the cortex. Finally, we will discuss how estrogens may influence cognitive function through the modulation of neuronal structure, and the implications this may have on the treatment of a range of brain disorders.
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Affiliation(s)
- Katherine Sellers
- Department of Basic and Clinical Neuroscience, The James Black Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, UK
| | - Pooja Raval
- Department of Basic and Clinical Neuroscience, The James Black Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, UK
| | - Deepak P Srivastava
- Department of Basic and Clinical Neuroscience, The James Black Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9NU, UK.
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146
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Jones KA, Eng AG, Raval P, Srivastava DP, Penzes P. Scaffold protein X11α interacts with kalirin-7 in dendrites and recruits it to Golgi outposts. J Biol Chem 2014; 289:35517-29. [PMID: 25378388 PMCID: PMC4271236 DOI: 10.1074/jbc.m114.587709] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Pyramidal neurons in the mammalian forebrain receive their synaptic inputs through their dendritic trees, and dendritic spines are the sites of most excitatory synapses. Dendritic spine structure is important for brain development and plasticity. Kalirin-7 is a guanine nucleotide-exchange factor for the small GTPase Rac1 and is a critical regulator of dendritic spine remodeling. The subcellular localization of kalirin-7 is thought to be important for regulating its function in neurons. A yeast two-hybrid screen has identified the adaptor protein X11α as an interacting partner of kalirin-7. Here, we show that kalirin-7 and X11α form a complex in the brain, and this interaction is mediated by the C terminus of kalirin-7. Kalirin-7 and X11α co-localize at excitatory synapses in cultured cortical neurons. Using time-lapse imaging of fluorescence recovery after photobleaching, we show that X11α is present in a mobile fraction of the postsynaptic density. X11α also localizes to Golgi outposts in dendrites, and its overexpression induces the removal of kalirin-7 from spines and accumulation of kalirin-7 in Golgi outposts. In addition, neurons overexpressing X11α displayed thinner spines. These data support a novel mechanism of regulation of kalirin-7 localization and function in dendrites, providing insight into signaling pathways underlying neuronal plasticity. Dissecting the molecular mechanisms of synaptic structural plasticity will improve our understanding of neuropsychiatric and neurodegenerative disorders, as kalirin-7 has been associated with schizophrenia and Alzheimer disease.
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Affiliation(s)
| | - Andrew G Eng
- the Interdepartmental Neuroscience Graduate Program, Northwestern University, Chicago, Illinois 60611, and
| | - Pooja Raval
- the Department of Neuroscience and Centre for the Cellular Basis of Behaviour, The James Black Centre, Institute of Psychiatry, King's College London, London SE5 9NU, United Kingdom
| | - Deepak P Srivastava
- From the Departments of Physiology and the Department of Neuroscience and Centre for the Cellular Basis of Behaviour, The James Black Centre, Institute of Psychiatry, King's College London, London SE5 9NU, United Kingdom
| | - Peter Penzes
- From the Departments of Physiology and Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611,
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147
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Differential Tiam1/Rac1 activation in hippocampal and cortical neurons mediates differential spine shrinkage in response to oxygen/glucose deprivation. J Cereb Blood Flow Metab 2014; 34:1898-906. [PMID: 25248834 PMCID: PMC4269742 DOI: 10.1038/jcbfm.2014.158] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 08/18/2014] [Accepted: 08/20/2014] [Indexed: 01/09/2023]
Abstract
Distinct neuronal populations show differential sensitivity to global ischemia, with hippocampal CA1 neurons showing greater vulnerability compared to cortical neurons. The mechanisms that underlie differential vulnerability are unclear, and we hypothesize that intrinsic differences in neuronal cell biology are involved. Dendritic spine morphology changes in response to ischemic insults in vivo, but cell type-specific differences and the molecular mechanisms leading to such morphologic changes are unexplored. To directly compare changes in spine size in response to oxygen/glucose deprivation (OGD) in cortical and hippocampal neurons, we used separate and equivalent cultures of each cell type. We show that cortical neurons exhibit significantly greater spine shrinkage compared to hippocampal neurons. Rac1 is a Rho-family GTPase that regulates the actin cytoskeleton and is involved in spine dynamics. We show that Rac1 and the Rac guanine nucleotide exchange factor (GEF) Tiam1 are differentially activated by OGD in hippocampal and cortical neurons. Hippocampal neurons express more Tiam1 than cortical neurons, and reducing Tiam1 expression in hippocampal neurons by shRNA enhances OGD-induced spine shrinkage. Tiam1 knockdown also reduces hippocampal neuronal vulnerability to OGD. This work defines fundamental differences in signalling pathways that regulate spine morphology in distinct neuronal populations that may have a role in the differential vulnerability to ischemia.
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148
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Smith KR, Kopeikina KJ, Fawcett-Patel JM, Leaderbrand K, Gao R, Schürmann B, Myczek K, Radulovic J, Swanson GT, Penzes P. Psychiatric risk factor ANK3/ankyrin-G nanodomains regulate the structure and function of glutamatergic synapses. Neuron 2014; 84:399-415. [PMID: 25374361 DOI: 10.1016/j.neuron.2014.10.010] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2014] [Indexed: 01/21/2023]
Abstract
Recent evidence implicates glutamatergic synapses as key pathogenic sites in psychiatric disorders. Common and rare variants in the ANK3 gene, encoding ankyrin-G, have been associated with bipolar disorder, schizophrenia, and autism. Here we demonstrate that ankyrin-G is integral to AMPAR-mediated synaptic transmission and maintenance of spine morphology. Using superresolution microscopy we find that ankyrin-G forms distinct nanodomain structures within the spine head and neck. At these sites, it modulates mushroom spine structure and function, probably as a perisynaptic scaffold and barrier within the spine neck. Neuronal activity promotes ankyrin-G accumulation in distinct spine subdomains, where it differentially regulates NMDA receptor-dependent plasticity. These data implicate subsynaptic nanodomains containing a major psychiatric risk molecule, ankyrin-G, as having location-specific functions and open directions for basic and translational investigation of psychiatric risk molecules.
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Affiliation(s)
- Katharine R Smith
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA
| | - Katherine J Kopeikina
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA
| | - Jessica M Fawcett-Patel
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA
| | - Katherine Leaderbrand
- Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA
| | - Ruoqi Gao
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA
| | - Britta Schürmann
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA
| | - Kristoffer Myczek
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA
| | - Jelena Radulovic
- Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA; Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA
| | - Geoffrey T Swanson
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA
| | - Peter Penzes
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA; Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611 USA.
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149
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Hu W, MacDonald ML, Elswick DE, Sweet RA. The glutamate hypothesis of schizophrenia: evidence from human brain tissue studies. Ann N Y Acad Sci 2014; 1338:38-57. [PMID: 25315318 DOI: 10.1111/nyas.12547] [Citation(s) in RCA: 169] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A number of studies have indicated that antagonists of the N-methyl-d-aspartate subtypes of glutamate receptors can cause schizophrenia-like symptoms in healthy individuals and exacerbate symptoms in individuals with schizophrenia. These findings have led to the glutamate hypothesis of schizophrenia. Here we review the evidence for this hypothesis in postmortem studies of brain tissue from individuals affected by schizophrenia, summarizing studies of glutamate neuron morphology, of expression of glutamate receptors and transporters, and of the synthesizing and metabolizing enzymes for glutamate and its co-agonists. We found consistent evidence of morphological alterations of dendrites of glutamatergic neurons in the cerebral cortex of subjects with schizophrenia and of reduced levels of the axon bouton marker synaptophysin. There were no consistent alterations of mRNA expression of glutamate receptors, although there has been limited study of the corresponding proteins. Studies of the glutamate metabolic pathway have been limited, although there is some evidence that excitatory amino acid transporter-2, glutamine synthetase, and glutaminase have altered expression in schizophrenia. Future studies would benefit from additional direct examination of glutamatergic proteins. Further advances, such as selective testing of synaptic microdomains, cortical layers, and neuronal subtypes, may also be required to elucidate the nature of glutamate signaling impairments in schizophrenia.
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Affiliation(s)
- Wei Hu
- Department of Behavioral Medicine and Psychiatry, West Virginia University Health Sciences Center, Morgantown, West Virginia
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150
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Chazeau A, Mehidi A, Nair D, Gautier JJ, Leduc C, Chamma I, Kage F, Kechkar A, Thoumine O, Rottner K, Choquet D, Gautreau A, Sibarita JB, Giannone G. Nanoscale segregation of actin nucleation and elongation factors determines dendritic spine protrusion. EMBO J 2014; 33:2745-64. [PMID: 25293574 DOI: 10.15252/embj.201488837] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Actin dynamics drive morphological remodeling of neuronal dendritic spines and changes in synaptic transmission. Yet, the spatiotemporal coordination of actin regulators in spines is unknown. Using single protein tracking and super-resolution imaging, we revealed the nanoscale organization and dynamics of branched F-actin regulators in spines. Branched F-actin nucleation occurs at the PSD vicinity, while elongation occurs at the tip of finger-like protrusions. This spatial segregation differs from lamellipodia where both branched F-actin nucleation and elongation occur at protrusion tips. The PSD is a persistent confinement zone for IRSp53 and the WAVE complex, an activator of the Arp2/3 complex. In contrast, filament elongators like VASP and formin-like protein-2 move outwards from the PSD with protrusion tips. Accordingly, Arp2/3 complexes associated with F-actin are immobile and surround the PSD. Arp2/3 and Rac1 GTPase converge to the PSD, respectively, by cytosolic and free-diffusion on the membrane. Enhanced Rac1 activation and Shank3 over-expression, both associated with spine enlargement, induce delocalization of the WAVE complex from the PSD. Thus, the specific localization of branched F-actin regulators in spines might be reorganized during spine morphological remodeling often associated with synaptic plasticity.
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Affiliation(s)
- Anaël Chazeau
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Amine Mehidi
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Deepak Nair
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Jérémie J Gautier
- CNRS UPR3082, Laboratoire d'Enzymologie et Biochimie Structurales, Gif-sur-Yvette Cedex, France
| | - Cécile Leduc
- University Bordeaux, LP2N, Talence, France CNRS & Institut d'Optique, LP2N, Talence, France
| | - Ingrid Chamma
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Frieda Kage
- Division of Molecular Cell Biology, Zoological Institute, Technical University Braunschweig, Braunschweig, Germany
| | - Adel Kechkar
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Olivier Thoumine
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technical University Braunschweig, Braunschweig, Germany Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Daniel Choquet
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Alexis Gautreau
- CNRS UPR3082, Laboratoire d'Enzymologie et Biochimie Structurales, Gif-sur-Yvette Cedex, France
| | - Jean-Baptiste Sibarita
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
| | - Grégory Giannone
- Interdisciplinary Institute for Neuroscience, University Bordeaux UMR 5297, Bordeaux, France CNRS, Interdisciplinary Institute for Neuroscience UMR 5297, Bordeaux, France
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