Number and Density of AMPA Receptors in Single Synapses in Immature Cerebellum

Tanaka, Junichi; Matsuzaki, Masunori; Tarusawa, Etsuko; Momiyama, Akiko; Molnár, Elek; Kasai, Hideaki; Shigemoto, Ryuichi

doi:10.1523/jneurosci.4256-04.2005

Cited by 157 publications

(168 citation statements)

References 48 publications

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“…In addition to the variability in the number of receptors, inhomogeneity of the two-dimensional distribution of AMPA receptors (AMPARs) within single postsynaptic membrane specialization has also been reported (Baude et al, 1995;Kharazia and Weinberg, 1997;Nusser et al, 1998). Our SDS-digested freeze-fracture replica immunolabeling method (SDS-FRL) (Fujimoto, 1995;Hagiwara et al, 2005;Masugi-Tokita et al, 2007) has almost one-to-one detection sensitivity to AMPARs (Tanaka et al, 2005). This method enabled us to reveal intrasynaptic microclusters of AMPARs in parallel fiber-Purkinje cell (PF-PC) synapses and their highly homogeneous distribution without such clustering in climbing fiber-Purkinje cell (CF-PC) synapses (Masugi-Tokita et al, 2007).…”

Section: Introductionmentioning

confidence: 95%

“…We labeled AMPARs with an antibody that specifically recognizes all four subunits (GluR1-4) of the AMPARs (Nusser et al, 1998;Tanaka et al, 2005;Masugi-Tokita et al, 2007). Immunoparticles for AMPARs in the RG synapses were found all over the IMP cluster ( Fig.…”

Section: Ampars Are Differentially Distributed In the Rg And Cg Synapsesmentioning

confidence: 99%

“…6 A), and thus, where the number of AMPARs is proportional to the synaptic area (Fig. 3A) (Takumi et al, 1999;Tanaka et al, 2005), the strength of the synapse can be approximately estimated by the size of the synapse. Extreme profiles to which this simple rule does not apply have never been encountered.…”

Section: The Amplitude Of Ampar and Nmdar Quantal Response Primarily mentioning

confidence: 99%

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Input-Specific Intrasynaptic Arrangements of Ionotropic Glutamate Receptors and Their Impact on Postsynaptic Responses

Tarusawa¹,

Matsui²,

Budisantoso³

et al. 2009

J. Neurosci.

110

157

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To examine the intrasynaptic arrangement of postsynaptic receptors in relation to the functional role of the synapse, we quantitatively analyzed the two-dimensional distribution of AMPA and NMDA receptors (AMPARs and NMDARs, respectively) using SDS-digested freeze-fracture replica labeling (SDS-FRL) and assessed the implication of distribution differences on the postsynaptic responses by simulation. In the dorsal lateral geniculate nucleus, corticogeniculate (CG) synapses were twice as large as retinogeniculate (RG) synapses but expressed similar numbers ofAMPARs.Two-dimensionalviewsofreplicasrevealedthatAMPARsformmicroclustersinbothsynapsestoasimilarextent,resultinginlarger AMPAR-lacking areas in the CG synapses. Despite the broad difference in the AMPAR distribution within a synapse, our simulations based on the actual receptor distributions suggested that the AMPAR quantal response at individual RG synapses is only slightly larger in amplitude, less variable, and faster in kinetics than that at CG synapses having a similar number of the receptors. NMDARs at the CG synapses were expressed twice as many as those in the RG synapses. Electrophysiological recordings confirmed a larger contribution of NMDAR relative to AMPAR-mediated responses in CG synapses. We conclude that synapse size and the density and distribution of receptors have minor influences on quantal responses and that the number of receptors acts as a predominant postsynaptic determinant of the synaptic strength mediated by both the AMPARs and NMDARs.

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Section: Introductionmentioning

confidence: 95%

Section: Ampars Are Differentially Distributed In the Rg And Cg Synapsesmentioning

confidence: 99%

Section: The Amplitude Of Ampar and Nmdar Quantal Response Primarily mentioning

confidence: 99%

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Input-Specific Intrasynaptic Arrangements of Ionotropic Glutamate Receptors and Their Impact on Postsynaptic Responses

Tarusawa¹,

Matsui²,

Budisantoso³

et al. 2009

J. Neurosci.

110

157

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“…A cluster of IMPs on the E-face of the plasma membrane represents the postsynaptic membrane specialization of glutamatergic synapses (Harris and Landis, 1986). Virtually all E-face IMP clusters were labeled with immunogold particles using a panAMPAR (GluR1-4) antibody (Nusser et al, 1998), which has almost an one-to-one detection sensitivity in SDS-FRL (Tanaka et al, 2005) (Fig. 5 A, I; see Fig.…”

Section: Ampar Distributionmentioning

confidence: 99%

“…3A), the actual value of the open AMPAR number would fall somewhere in between these two values. It has been determined previously that our SDS-FRL has high sensitivity of immunolabeling with nearly one-to-one detection for AMPARs (Tanaka et al, 2005;Tarusawa et al, 2009). Using the AMPAR immunoparticle distribution revealed by this method, we simulated the AMPAR response to glutamate release.…”

Section: Validity Of the N Glu And D Glu Parameters Used In Calculatimentioning

confidence: 99%

Mechanisms Underlying Signal Filtering at a Multisynapse Contact

Budisantoso¹,

Matsui²,

Kamasawa³

et al. 2012

J. Neurosci.

111

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Visual information must be relayed through the lateral geniculate nucleus before it reaches the visual cortex. However, not all spikes created in the retina lead to postsynaptic spikes and properties of the retinogeniculate synapse contribute to this filtering. To understand the mechanisms underlying this filtering process, we conducted electrophysiology to assess the properties of signal transmission in the Long-Evans rat. We also performed SDS-digested freeze-fracture replica labeling to quantify the receptor and transporter distribution, as well as EM reconstruction to describe the 3D structure. To analyze the impact of transmitter diffusion on the activity of the receptors, simulations were integrated. We identified that a large contributor to the filtering is the marked paired-pulse depression at this synapse, which was intensified by the morphological characteristics of the contacts. The broad presynaptic and postsynaptic contact area restricts transmitter diffusion two dimensionally. Additionally, the presence of multiple closely arranged release sites invites intersynaptic spillover, which causes desensitization of AMPA receptors. The presence of AMPA receptors that slowly recover from desensitization along with the high presynaptic release probability and multivesicular release at each synapse also contribute to the depression. These features contrast with many other synapses where spatiotemporal spread of transmitter is limited by rapid transmitter clearance allowing synapses to operate more independently. We propose that the micrometer-order structure can ultimately affect the visual information processing.

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Quantum Dots for Detection, Identification and Tracking of Single Biomolecules in Tissue and Cells

Loukanov¹,

Emin²

2012

Intelligent Nanomaterials

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The study of basic cell ultrastructure and intracellular physiological functions has been greatly aided by detection and identification of single macromolecules. Since the current in situ labeling methods for directly correlative (light and electron) microscopy observations have a number of substantial limitations, the semiconductor nanocrystals quantum dots gain distinguished with long-term imaging and high photostability. The quantum dots (Qdots) have quickly filled in the role, being found to be superior to traditional organic dyes on several counts. It has been estimated that Qdots are 20 times brighter and 100 times more stable than traditional fluorescent reporters. Nowadays, a wide variety of quantum dots conjugated to secondary antibodies suitable for multiple labeling have become commercially available. They make possible the study of biological processes, both in the membrane or in the cytoplasm, at a truly molecular scale and with high spatial and temporal resolutions. By applying Qdots with different size and color light we might achieve multiple labeling of proteins. However, the use of particles with different size is problematic for high-resolution imaging, semi-quantitative measurement of epitope numbers, or when epitope density is high. Recently we report new electron microscopy method for immunolabeling, where two approaches are performed to distinguish yet unattainable spatial

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Number and Density of AMPA Receptors in Single Synapses in Immature Cerebellum

Abstract: The number of ionotropic receptors in synapses is

Cited by 157 publications

References 48 publications

Input-Specific Intrasynaptic Arrangements of Ionotropic Glutamate Receptors and Their Impact on Postsynaptic Responses

Input-Specific Intrasynaptic Arrangements of Ionotropic Glutamate Receptors and Their Impact on Postsynaptic Responses

Mechanisms Underlying Signal Filtering at a Multisynapse Contact

Quantum Dots for Detection, Identification and Tracking of Single Biomolecules in Tissue and Cells

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