Regulation of AMPA Receptor GluR1 Subunit Surface Expression by a 4.1N-Linked Actin Cytoskeletal Association

Shen, Lei; Feng, Liang; Walensky, Loren D.; Huganir, Richard L.

doi:10.1523/jneurosci.20-21-07932.2000

Cited by 276 publications

(248 citation statements)

References 63 publications

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“…It has recently been suggested that electrical activity controls the size and number of spines 21,22,[39][40][41][42] , and that the expression of glutamate receptors is tightly regulated by abundant cytoskeletal structures present in spines [3][4][5] . One can therefore surmise that spine structures are a key determinant of synaptic efficacy via control of the distribution of the AMPA receptors 9,10,43 .…”

Section: Discussionmentioning

confidence: 99%

“…Substantial biochemical evidence indicates that glutamate receptors in postsynaptic densities (PSDs) are regulated by various protein machineries that link the receptors to the cytoskeleton 3,4,5 and that control the insertion [6][7][8][9][10] and phosphorylation of the receptors 11,12 . Individual dendritic spines have been thought to act as functional compartments of glutamate receptor expression, given that they are physically and thus metabolically separated from the body of the dendrite by the narrow spine neck [13][14][15][16] .…”

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Dendritic spine geometry is critical for AMPA receptor expression in hippocampal CA1 pyramidal neurons

et al. 2001

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Dendritic spines serve as preferential sites of excitatory synaptic connections and are pleomorphic. To address the structure-function relationship of the dendritic spines, we used two-photon uncaging of glutamate to allow mapping of functional glutamate receptors at the level of the single synapse. Our analyses of the spines of CA1 pyramidal neurons reveal that AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)-type glutamate receptors are abundant (up to 150/ spine) in mushroom spines but sparsely distributed in thin spines and filopodia. The latter may be serving as the structural substrates of the silent synapses that have been proposed to play roles in development and plasticity of synaptic transmission. Our data indicate that distribution of functional AMPA receptors is tightly correlated with spine geometry and that receptor activity is independently regulated at the level of single spines.Most excitatory synaptic transmission in the mammalian central nervous system relies on glutamate as a neurotransmitter, and postsynaptic glutamate receptors are central in both the acquisition and maintenance of memory 1, 2 . Substantial biochemical evidence indicates that glutamate receptors in postsynaptic densities (PSDs) are regulated by various protein machineries that link the receptors to the cytoskeleton 3,4,5 and that control the insertion [6][7][8][9][10] and phosphorylation of the receptors 11,12 . Individual dendritic spines have been thought to act as functional compartments of glutamate receptor expression, given that they are physically and thus metabolically separated from the body of the dendrite by the narrow spine neck [13][14][15][16] . Indeed, the Hebbian principle of learning as well as most theories of neuronal networks assume that the strength of synaptic connections is subject to independent control 17 . Moreover, spine geometry has been proposed to be a key determinant of synaptic function and memory in the brain 13, 14, 18-22 . Correspondence to: Haruo Kasai. These various hypotheses have not been tested experimentally, however, because it is not possible to systematically investigate postsynaptic glutamate sensitivities at the level of the individual spine by classical electrophysiological approaches 16,23 . Also, the number of functional AMPA-sensitive glutamate receptors in individual spines has not been estimated directly. Two-photon excitation of caged-glutamate compounds may overcome these difficulties 24 as a result of the inherent three-dimensional resolution of neurotransmitter application associated with this technique. However, caged-glutamate compounds with a cross-section for two-photon absorption, a rate of photolysis, and a stability in aqueous solution sufficient for such studies have not previously been described [25][26][27] . NIH Public AccessWe developed a caged-glutamate compound and microscopic system for two-photon excitation that allowed systematic investigation of functional glutamate receptors at the level of the individual synapse. Our experiment...

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Section: Discussionmentioning

confidence: 99%

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Dendritic spine geometry is critical for AMPA receptor expression in hippocampal CA1 pyramidal neurons

et al. 2001

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“…It would adversely affect the functions of hippocampus following brain injuries and may underlie behavioral deficits. It is a synaptic membrane-associated protein, localized to post synaptic densities [59], and thought to play a role in trafficking of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors [60,61]. Recently SAP-97 depletion has been linked with cerebral ischemia [62].…”

Section: Discussionmentioning

confidence: 99%

Oxidative stress and modification of synaptic proteins in hippocampus after traumatic brain injury

Ansari

Roberts

Scheff

2008

Free Radical Biology and Medicine

277

220

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Oxidative stress, an imbalance between oxidants and antioxidants, contributes to the pathogenesis of traumatic brain injury (TBI). Oxidative neurodegeneration is a key mediator of exacerbated morphological responses and deficits in behavioral recoveries. The present study assessed early hippocampal sequential imbalance to possibly enhance antioxidant therapy. Young adult male Sprague-Dawley rats were subjected to a unilateral moderate cortical contusion. At various times post TBI, animals were killed and the hippocampus analyzed for antioxidants (GSH, GSSG, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, glucose-6-phosphate dehydrogenase, superoxide dismutase and catalase), and oxidants (acrolein,, protein carbonyl [PC] and 3-nitrotyrosine. Synaptic markers (synapsin-I, post synaptic density-95 [PSD-95], synapse associated protein-97 [SAP-97], growth associated protein-43 were also analyzed. All values were compared to sham operated animals. Significant time-dependent changes in antioxidants were observed as early as 3 h post trauma and paralleled increases in oxidants (4-HNE, acrolein and PC) with peak values obtained at 24-48 h. Time dependent changes in synaptic proteins (synapsin-I, PSD-95 and SAP-97) occurred well after levels of oxidants peaked. These results indicate that depletion of antioxidant systems following trauma could adversely affect synaptic function and plasticity. Early onset of oxidative stress suggests that the initial therapeutic window following TBI appears to be relatively short and it may be necessary to stagger selective types of anti-oxidant therapy to target specific oxidative components.

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“…39 ). Depolymerization of actin leads to a loss of AMPARs from the surface 27,40 and a decrease in synaptic efficacy 41 .…”

Section: When Do Ampars Take a Break?mentioning

confidence: 99%

Restless AMPA receptors: implications for synaptic transmission and plasticity

Lüscher

Frerking

2001

Trends in Neurosciences

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A central assumption in neurobiology holds that changes in the strength of individual synapses underlie changes in behavior. This concept is widely accepted in the case of learning and memory where LTP and LTD are the most compelling cellular models. It is therefore of great interest to understand, on a molecular level, how the brain regulates the strength of neuronal connections. We review a large body of evidence in support of the very straightforward regulation of synaptic strength by changing the number of postsynaptic receptors, and discuss the molecular machinery required for insertion and removal of AMPA receptors.The hypothesis that insertion of AMPA receptors (AMPARs) underlies the increase of synaptic strength associated with LTP was put forward almost 20 years ago 1 , but was largely ignored until the mid-1990s, resurfacing with quantal analysis of LTP (Ref. 2 ). However, only recently has it become the subject of direct experimental scrutiny.The spark for the myriad of research published in the past few years in the field was experiments conducted independently by two groups 3,4 , in which single connections between CA3 axons and CA1 pyramidal cells in acute hippocampal slices were functionally isolated and in some cases yielded only responses from NMDA receptors (NMDARs) and not AMPARs. Inducing LTP, however, caused the appearance of AMPAR mediated excitatory postsynaptic currents (EPSCs). This led to the proposal that a fraction of 'silent' synapses contain only NMDARs, and thus are functionally inactive at normal resting potential, but maintain the capability to undergo LTP, which would be expressed by AMPAR insertion. Although alternative explanations for these results have been proposed 5,6 , synapses with NMDARs but not AMPARs have now been directly identified anatomically in cultured hippocampal neurons using immunofluorescence 7,8 and with immuno-gold preparations visualized by electron microscopy in hippocampal slices 9-11 .AMPARs move from the cytoplasm to the surface and back again Constitutive recyclingIf LTP expression is caused by postsynaptic AMPAR insertion, it must be the case that AMPARs can be inserted into and removed from the postsynaptic membrane on a relatively rapid time scale. To test this experimentally, CA1 pyramidal cells in acute hippocampal slices * Christian.Luscher@medecine.unige.ch.

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Regulation of AMPA Receptor GluR1 Subunit Surface Expression by a 4.1N-Linked Actin Cytoskeletal Association

Cited by 276 publications

References 63 publications

Dendritic spine geometry is critical for AMPA receptor expression in hippocampal CA1 pyramidal neurons

Dendritic spine geometry is critical for AMPA receptor expression in hippocampal CA1 pyramidal neurons

Oxidative stress and modification of synaptic proteins in hippocampus after traumatic brain injury

Restless AMPA receptors: implications for synaptic transmission and plasticity

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