Two Families of TARP Isoforms that Have Distinct Effects on the Kinetic Properties of AMPA Receptors and Synaptic Currents

Cho, Chang-Hoon; St-Gelais, Fannie; Zhang, Wei; Tomita, Susumu; Howe, James R.

doi:10.1016/j.neuron.2007.08.024

Cited by 159 publications

(257 citation statements)

References 51 publications

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“…We next extended our analysis of colocalization and immobilization to other TARPs that are known to interact with and modulate the functions of AMPA-Rs (17,19,20,33). We chose γ-3, γ-4, and γ-8, which are functionally similar to γ-2.…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies have shown that TARPs directly interact with AMPA-Rs (11,13,27) and regulate both their localization and gating (14)(15)(16)(17)(18)(19)(20)22). The stoichiometry of TARP/AMPA-R complexes was recently deduced indirectly from functional population assays to be a maximum of four TARPs per AMPA-R complex (30).…”

Section: Resultsmentioning

confidence: 99%

“…TARPs regulate AMPA-R function by several mechanisms. They mediate the efficient cell surface expression of AMPA-Rs, modulate gating, affect agonist efficacy, and even attenuate intracellular polyamine block of calciumpermeable AMPA-Rs (13)(14)(15)(16)(17)(18)(19)(20)(21)(22). The effect of stargazin (γ-2) and other TARPs on GluA1 is not neuron specific and can be accurately mimicked in nonneuronal mammalian cells (18,(23)(24)(25), as well as Xenopus oocytes (13,14,17,26,27), suggesting that the basic mechanisms for TARP/AMPA-R interaction and TARPmediated regulation of AMPA-R trafficking are preserved in nonneuronal cells.…”

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confidence: 99%

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AMPA receptor/TARP stoichiometry visualized by single-molecule subunit counting

Hastie

Ulbrich

Wang

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Members of the transmembrane AMPA receptor-regulatory protein (TARP) family modulate AMPA receptor (AMPA-R) trafficking and function. AMPA-Rs consist of four pore-forming subunits. Previous studies show that TARPs are an integral part of the AMPA-R complex, acting as accessory subunits for mature receptors in vivo. The TARP/AMPA-R stoichiometry was previously measured indirectly and found to be variable and dependent on TARP expression level, with at most four TARPs associated with each AMPA-R complex. Here, we use a single-molecule technique in live cells that selectively images proteins located in the plasma membrane to directly count the number of TARPs associated with each AMPA-R complex. Although individual GFP-tagged TARP subunits are observed as freely diffusing fluorescent spots on the surface of Xenopus laevis oocytes when expressed alone, coexpression with AMPA-RmCherry immobilizes the stargazin-GFP spots at sites of AMPA-RmCherry, consistent with complex formation. We determined the number of TARP molecules associated with each AMPA-R by counting bleaching steps for three different TARP family members: γ-2, γ-3, and γ-4. We confirm that the TARP/AMPA-R stoichiometry depends on TARP expression level and discover that the maximum number of TARPs per AMPA-R complex falls into two categories: up to four γ-2 or γ-3 subunits, but rarely above two for γ-4 subunit. This unexpected AMPA-R/TARP stoichiometry difference has important implications for the assembly and function of TARP/ AMPA-R complexes.single-molecule counting | TIRF | glutamate receptors | stargazin G lutamate is the main excitatory neurotransmitter in the mammalian CNS. Most fast excitatory synaptic transmission in the brain is mediated by AMPA receptors (AMPA-Rs). Four AMPA-R subunits, GluA1-4, contribute to the heterotetrameric assemblies of the AMPA-R (1-4). The localization of AMPA-Rs to the postsynaptic membrane is regulated by a large number of proteins through multiple mechanisms and plays important roles in synaptic plasticity (5-9).Transmembrane AMPA-R regulatory proteins (TARPs) represent a family of AMPA-R regulatory proteins that are tightly associated with AMPA-Rs, and can be considered auxiliary AMPA-R subunits (10-12). TARPs regulate AMPA-R function by several mechanisms. They mediate the efficient cell surface expression of AMPA-Rs, modulate gating, affect agonist efficacy, and even attenuate intracellular polyamine block of calciumpermeable AMPA-Rs (13-22). The effect of stargazin (γ-2) and other TARPs on GluA1 is not neuron specific and can be accurately mimicked in nonneuronal mammalian cells (18,(23)(24)(25), as well as Xenopus oocytes (13,14,17,26,27), suggesting that the basic mechanisms for TARP/AMPA-R interaction and TARPmediated regulation of AMPA-R trafficking are preserved in nonneuronal cells.Although much is known about the interaction domains on the classical TARPs (γ-2, γ-3, γ-4, and γ-8) and AMPA-Rs that mediate assembly and modulation (13,23,24,27,28), far less is known about the stoichiometry of the TARP/AMPA-R...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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AMPA receptor/TARP stoichiometry visualized by single-molecule subunit counting

Hastie

Ulbrich

Wang

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…Overall, KA2 acts as an accessory subunit that controls in concert both the functional properties of KARs and their expression at the membrane surface (Pinheiro and Mulle, 2006), similarly to transmembrane-associated proteins TARPs for AMPA receptors (Cho et al, 2007;Milstein et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

GluR6/KA2 Kainate Receptors Mediate Slow-Deactivating Currents

Barberis

Sachidhanandam²,

Mulle³

2008

Journal of Neuroscience

126

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Kainate receptors (KARs) are ionotropic glutamate receptors contributing to EPSCs with a slow-decaying component that is likely essential for synaptic integration. The slow kinetics of KAR-EPSCs markedly contrasts with the fast kinetics reported for recombinant KARs expressed in heterologous systems, for reasons that remain unexplained. Here we have studied the properties of recombinant heteromeric GluR6/KA2 receptors, which compose synaptic KARs. We report that, in response to brief glutamate applications, currents mediated by recombinant GluR6/KA2 receptors, but not GluR6 receptors, decay with a time course similar to KAR-EPSCs. Model simulations suggest that, after brief agonist exposures, GluR6/KA2 currents undergo slow deactivation caused by the stabilization of partially bound open states. We propose, therefore, that the GluR6/KA2 gating features could contribute to the slow KAR-EPSC decay kinetics.

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“…The micropipette tips were custom-made using filamented borosilicate glass capillaries (BF150-86-10, Sutter Instruments). sEPSCs and sIPSCs were recorded as described previously (50,51), with detailed settings described in SI Appendix, Fig. S1.…”

Section: Methodsmentioning

confidence: 99%

Single-neuron identification of chemical constituents, physiological changes, and metabolism using mass spectrometry

Zhu

Zou

Wang

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

105

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The use of single-cell assays has emerged as a cutting-edge technique during the past decade. Although single-cell mass spectrometry (MS) has recently achieved remarkable results, deep biological insights have not yet been obtained, probably because of various technical issues, including the unavoidable use of matrices, the inability to maintain cell viability, low throughput because of sample pretreatment, and the lack of recordings of cell physiological activities from the same cell. In this study, we describe a patch clamp/MS-based platform that enables the sensitive, rapid, and in situ chemical profiling of single living neurons. This approach integrates modified patch clamp technique and modified MS measurements to directly collect and detect nanoliter-scale samples from the cytoplasm of single neurons in mice brain slices. Abundant possible cytoplasmic constituents were detected in a single neuron at a relatively fast rate, and over 50 metabolites were identified in this study. The advantages of direct, rapid, and in situ sampling and analysis enabled us to measure the biological activities of the cytoplasmic constituents in a single neuron, including comparing neuron types by cytoplasmic chemical constituents; observing changes in constituent concentrations as the physiological conditions, such as age, vary; and identifying the metabolic pathways of small molecules.single neuron | mass spectrometry | metabolism | patch clamp

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Two Families of TARP Isoforms that Have Distinct Effects on the Kinetic Properties of AMPA Receptors and Synaptic Currents

Cited by 159 publications

References 51 publications

AMPA receptor/TARP stoichiometry visualized by single-molecule subunit counting

AMPA receptor/TARP stoichiometry visualized by single-molecule subunit counting

GluR6/KA2 Kainate Receptors Mediate Slow-Deactivating Currents

Single-neuron identification of chemical constituents, physiological changes, and metabolism using mass spectrometry

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