Rapid Spine Delivery and Redistribution of AMPA Receptors After Synaptic NMDA Receptor Activation
11 Jun 1999-Science (American Association for the Advancement of Science)-Vol. 284, Iss: 5421, pp 1811-1816
TL;DR: Tetanic synaptic stimulation induced a rapid delivery of tagged receptors into dendritic spines as well as clusters in dendrites and may contribute to the enhanced AMPA receptor-mediated transmission observed during long-term potentiation and activity-dependent synaptic maturation.
Abstract: To monitor changes in alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor distribution in living neurons, the AMPA receptor subunit GluR1 was tagged with green fluorescent protein (GFP). This protein (GluR1-GFP) was functional and was transiently expressed in hippocampal CA1 neurons. In dendrites visualized with two-photon laser scanning microscopy or electron microscopy, most of the GluR1-GFP was intracellular, mimicking endogenous GluR1 distribution. Tetanic synaptic stimulation induced a rapid delivery of tagged receptors into dendritic spines as well as clusters in dendrites. These postsynaptic trafficking events required synaptic N-methyl-D-aspartate (NMDA) receptor activation and may contribute to the enhanced AMPA receptor-mediatedtransmission observed during long-term potentiation and activity-dependent synaptic maturation.
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TL;DR: Multiphoton microscopy has found a niche in the world of biological imaging as the best noninvasive means of fluorescence microscopy in tissue explants and living animals and its use is now increasing exponentially.
Abstract: Multiphoton microscopy (MPM) has found a niche in the world of biological imaging as the best noninvasive means of fluorescence microscopy in tissue explants and living animals. Coupled with transgenic mouse models of disease and 'smart' genetically encoded fluorescent indicators, its use is now increasing exponentially. Properly applied, it is capable of measuring calcium transients 500 microm deep in a mouse brain, or quantifying blood flow by imaging shadows of blood cells as they race through capillaries. With the multitude of possibilities afforded by variations of nonlinear optics and localized photochemistry, it is possible to image collagen fibrils directly within tissue through nonlinear scattering, or release caged compounds in sub-femtoliter volumes.
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TL;DR: A simple model is described that unifies much of the data that previously were viewed as contradictory about the molecular mechanisms of this long-lasting increase in synaptic strength in the hippocampus.
Abstract: Long-term potentiation of synaptic transmission in the hippocampus is the leading experimental model for the synaptic changes that may underlie learning and memory. This review presents a current understanding of the molecular mechanisms of this long-lasting increase in synaptic strength and describes a simple model that unifies much of the data that previously were viewed as contradictory.
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TL;DR: The growing literature that supports a critical role for AMPA receptors trafficking in LTP and LTD is reviewed, focusing on the roles proposed for specific AMPA receptor subunits and their interacting proteins.
Abstract: Activity-dependent changes in synaptic function are believed to underlie the formation of memories. Two prominent examples are long-term potentiation (LTP) and long-term depression (LTD), whose mechanisms have been the subject of considerable scrutiny over the past few decades. Here we review the growing literature that supports a critical role for AMPA receptor trafficking in LTP and LTD, focusing on the roles proposed for specific AMPA receptor subunits and their interacting proteins. While much work remains to understand the molecular basis for synaptic plasticity, recent results on AMPA receptor trafficking provide a clear conceptual framework for future studies.
2,587 citations
Cites background or result from "Rapid Spine Delivery and Redistribu..."
...Indeed, given the much larger space occupied by nonsynaptic regions, nonsynaptic AMPARs appear to outnumber synaptic AMPARs by quite a large margin (Shi et al. 1999)....
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...This restriction from synapses is in contrast with what is found in dissociated cultured neurons in which expression of recombinant GluR1 concentrates at synapses (Lissin et al. 1998, Shi et al. 1999)....
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...Optical Detection of Recombinant AMPA Receptor Trafficking During LTP To monitor AMPAR trafficking in living tissue, one study generated and acutely expressed GFP-tagged GluR1 receptors in organotypic hippocampal slices (Shi et al. 1999)....
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TL;DR: Genetic mutations that prevent persistent activation of CaMKII block LTP, experience-dependent plasticity and behavioural memory, making this kinase a leading candidate in the search for the molecular basis of memory.
Abstract: Long-term potentiation (LTP) in the CA1 region of the hippocampus has been the primary model by which to study the cellular and molecular basis of memory. Calcium/calmodulin-dependent protein kinase II (CaMKII) is necessary for LTP induction, is persistently activated by stimuli that elicit LTP, and can, by itself, enhance the efficacy of synaptic transmission. The analysis of CaMKII autophosphorylation and dephosphorylation indicates that this kinase could serve as a molecular switch that is capable of long-term memory storage. Consistent with such a role, mutations that prevent persistent activation of CaMKII block LTP, experience-dependent plasticity and behavioural memory. These results make CaMKII a leading candidate in the search for the molecular basis of memory.
1,864 citations
Cites background from "Rapid Spine Delivery and Redistribu..."
...After NMDA receptor activation, AMPA receptors can move into spine...
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TL;DR: Lynch et al. as mentioned in this paper identified the cellular and molecu... cellular and memory cells in neuroscience is one of the most significant challenges in neuroscience and identified the most important genes for long-term potentiation and memory.
Abstract: Lynch, MA. Long-Term Potentiation and Memory. Physiol Rev 84: 87–136, 2004; 10.1152/physrev.00014.2003.—One of the most significant challenges in neuroscience is to identify the cellular and molecu...
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References
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TL;DR: The best understood form of long-term potentiation is induced by the activation of the N-methyl-d-aspartate receptor complex, which allows electrical events at the postsynaptic membrane to be transduced into chemical signals which, in turn, are thought to activate both pre- and post Synaptic mechanisms to generate a persistent increase in synaptic strength.
Abstract: Long-term potentiation of synaptic transmission in the hippocampus is the primary experimental model for investigating the synaptic basis of learning and memory in vertebrates. The best understood form of long-term potentiation is induced by the activation of the N-methyl-D-aspartate receptor complex. This subtype of glutamate receptor endows long-term potentiation with Hebbian characteristics, and allows electrical events at the postsynaptic membrane to be transduced into chemical signals which, in turn, are thought to activate both pre- and postsynaptic mechanisms to generate a persistent increase in synaptic strength.
11,123 citations
TL;DR: The application of molecular cloning technology to the study of the glutamate receptor system has led to an explosion of knowledge about the structure, expression, and function of this most important fast excitatory transmitter system in the mammalian brain.
Abstract: The application of molecular cloning technology to the study of the glutamate receptor system has led to an explosion of knowledge about the structure, expression, and function of this most important fast excitatory transmitter system in the mammalian brain. The first functional ionotropic glutamate receptor was cloned in 1989 (Hollmann et al 1989) , and the results of this molecular-based approach over the past three years are the focus of this review. We discuss the implications of and the new questions raised by this work-which is probably only a glance at this fascinating and complex signaling system found in brains from the snails to man. Glutamate receptors are found throughout the mammalian brain, where they constitute the major excitatory transmitter system. The longest-known and best-studied glutamate receptors are ligand-gated ion channels, also called ionotropic glutamate receptors , which are permeable to cations. They have traditionally been classified into three broad subtypes based upon pharmaco logical and electrophysiological data: a-amino-3-hydroxy-5-methyl-4isoxazole propionate (AMPA) receptors, kainate (KA) receptors , and N-methyl-D-aspartate (NMDA) receptors. Recently, however, a family of G protein-coupled glutamate receptors , which are also called metabotropic glutamate or transl -aminocyclopentanel ,3-dicarboxylate (tACPD) recep tors, was identified (Sugiyama et al 1987) . (For reviews of the classification and the pharmacological and electrophysiological properties of glutamate receptors see Mayer & Westbrook 1987, Collingridge & Lester 1989, Honore 1989, Monaghan et al 1989, Wroblewski & Danysz 1 989, Hansen &
4,079 citations
TL;DR: New fluorescent indicators for Ca2+ that are genetically encoded without cofactors and are targetable to specific intracellular locations are constructed and dubbed ‘cameleons’.
Abstract: Important Ca2+ signals in the cytosol and organelles are often extremely localized and hard to measure. To overcome this problem we have constructed new fluorescent indicators for Ca2+ that are genetically encoded without cofactors and are targetable to specific intracellular locations. We have dubbed these fluorescent indicators 'cameleons'. They consist of tandem fusions of a blue- or cyan-emitting mutant of the green fluorescent protein (GFP), calmodulin, the calmodulin-binding peptide M13, and an enhanced green- or yellow-emitting GFP. Binding of Ca2+ makes calmodulin wrap around the M13 domain, increasing the fluorescence resonance energy transfer (FRET) between the flanking GFPs. Calmodulin mutations can tune the Ca2+ affinities to measure free Ca2+ concentrations in the range 10(-8) to 10(-2) M. We have visualized free Ca2+ dynamics in the cytosol, nucleus and endoplasmic reticulum of single HeLa cells transfected with complementary DNAs encoding chimaeras bearing appropriate localization signals. Ca2+ concentration in the endoplasmic reticulum of individual cells ranged from 60 to 400 microM at rest, and 1 to 50 microM after Ca2+ mobilization. FRET is also an indicator of the reversible intermolecular association of cyan-GFP-labelled calmodulin with yellow-GFP-labelled M13. Thus FRET between GFP mutants can monitor localized Ca2+ signals and protein heterodimerization in individual live cells.
3,248 citations
TL;DR: Hippocampal slices prepared from 2-23-day-old neonates were maintained in culture at the interface between air and a culture medium and yielded thin slices which remain 1-4 cell layers thick and are characterized by a well preserved organotypic organization.
3,086 citations
TL;DR: It is shown that weak tetanic stimulation, which ordinarily leads only to early LTP, or repeated tetanization in the presence of protein-Synthesis inhibitors, each results in protein-synthesis-dependent late LTP; this indicates that the persistence of LTP depends not only on local events during its induction, but also on the prior activity of the neuron.
Abstract: Repeated stimulation of hippocampal neurons can induce an immediate and prolonged increase in synaptic strength that is called long-term potentiation (LTP)—the primary cellular model of memory in the mammalian brain1. An early phase of LTP (lasting less than three hours) can be dissociated from late-phase LTP by using inhibitors of transcription and translation2–8. Because protein synthesis occurs mainly in the cell body9–12, whereas LTP is input-specific, the question arises of how the synapse specificity of late LTP is achieved without elaborate intracellular protein trafficking. We propose that LTP initiates the creation of a short-lasting protein-synthesis-independent 'synaptic tag' at the potentiated synapse which sequesters the relevant protein(s) to establish late LTP. In support of this idea, we now show that weak tetanic stimulation, which ordinarily leads only to early LTP, or repeated tetanization in the presence of protein-synthesis inhibitors, each results in protein-synthesis-dependent late LTP, provided repeated tetanization has already been applied at another input to the same population of neurons. The synaptic tag decays in less than three hours. These findings indicate that the persistence of LTP depends not only on local events during its induction, but also on the prior activity of the neuron.
1,577 citations