scholarly journals Architecture of fully occupied Glua2 Ampa receptor – TARP complex elucidated by single particle cryo-electron microscopy

2016 ◽  
Author(s):  
Yan Zhao ◽  
Shanshuang Chen ◽  
Craig Yoshioka ◽  
Isabelle Baconguis ◽  
Eric Gouaux
Keyword(s):  
Ion Channel ◽  
Ampa Receptor ◽  
Ampa Receptors ◽  
Receptor Activation ◽  
Regulatory Proteins ◽  
Dimer Interface ◽  
Cryo Electron Microscopy ◽  
Excitatory Neurotransmission ◽  
Conformational Rearrangements ◽  
Kinetics Of

SummaryFast excitatory neurotransmission in the mammalian central nervous system is largely carried out by AMPA-sensitive ionotropic glutamate receptors. Localized within the postsynaptic density of glutamatergic spines, AMPA receptors are composed of heterotetrameric receptor assemblies associated with auxiliary subunits, the most common of which are transmembrane AMPA-receptor regulatory proteins (TARPs). The association of TARPs with AMPA receptors modulates the kinetics of receptor gating and pharmacology, as well as trafficking. Here we report the cryo-EM structure of the homomeric GluA2 AMPA receptor saturated with TARP γ2 subunits, showing how the TARPs are arranged with four-fold symmetry around the ion channel domain, making extensive interactions with the M1, M2 and M4 TM helices. Poised like partially opened ‘hands’ underneath the two-fold symmetric ligand binding domain (LBD) ‘clamshells’, one pair of TARPs are juxtaposed near the LBD dimer interface, while the other pair are near the LBD dimer-dimer interface. The extracellular ‘domains’ of TARP are positioned to not only modulate LBD ‘clamshell’ closure, but also to affect conformational rearrangements of the LBD layer associated with receptor activation and desensitization, while the TARP transmembrane (TM) domains buttress the ion channel pore.

scholarly journals Control of AMPA receptor activity by the extracellular loops of auxiliary proteins

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Irene Riva ◽  
Clarissa Eibl ◽  
Rudolf Volkmer ◽  
Anna L Carbone ◽  
Andrew JR Plested
Keyword(s):  
Ampa Receptor ◽  
Ampa Receptors ◽  
De Novo ◽  
Dominant Role ◽  
Mammalian Brain ◽  
Binding Assays ◽  
Receptor Kinetics ◽  
Receptor Complexes ◽  
Extracellular Loops ◽  
Kinetics Of

At synapses throughout the mammalian brain, AMPA receptors form complexes with auxiliary proteins, including TARPs. However, how TARPs modulate AMPA receptor gating remains poorly understood. We built structural models of TARP-AMPA receptor complexes for TARPs γ2 and γ8, combining recent structural studies and de novo structure predictions. These models, combined with peptide binding assays, provide evidence for multiple interactions between GluA2 and variable extracellular loops of TARPs. Substitutions and deletions of these loops had surprisingly rich effects on the kinetics of glutamate-activated currents, without any effect on assembly. Critically, by altering the two interacting loops of γ2 and γ8, we could entirely remove all allosteric modulation of GluA2, without affecting formation of AMPA receptor-TARP complexes. Likewise, substitutions in the linker domains of GluA2 completely removed any effect of γ2 on receptor kinetics, indicating a dominant role for this previously overlooked site proximal to the AMPA receptor channel gate.

Positive Allosteric Modulators of AMPA Receptors Reduce Proton-Induced Receptor Desensitization in Rat Hippocampal Neurons

2001 ◽  
Vol 85 (5) ◽  
pp. 2030-2038 ◽  
Author(s):  
Saobo Lei ◽  
Beverley A. Orser ◽  
Gregory R. L. Thatcher ◽  
James N. Reynolds ◽  
John F. MacDonald
Keyword(s):  
Ampa Receptor ◽  
Ampa Receptors ◽  
Hippocampal Neurons ◽  
Organic Nitrate ◽  
Receptor Desensitization ◽  
Open Probability ◽  
Ca1 Neurons ◽  
Hippocampal Ca1 ◽  
Rate Of Recovery ◽  
Kinetics Of

Whole-cell or outside-out patch recordings were used to investigate the effects of protons and positive modulators of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors on the desensitization of glutamate-evoked AMPA receptor currents in isolated hippocampal CA1 neurons. Protons inhibited glutamate-evoked currents (IC50 of 6.2 pH units) but also enhanced the apparent rate and extent of AMPA receptor desensitization. The proton-induced enhancement of desensitization could not be attributed to a reduction in the rate of recovery from desensitization or to a change in the kinetics of deactivation. Non-stationary variance analysis indicated that protons reduced maximum open probability without changing the conductance of AMPA channels. The positive modulators of AMPA receptor desensitization, cyclothiazide and GT-21-005 (an organic nitrate), reduced the proton sensitivity of AMPA receptor desensitization, which suggests that they interact with protons to diminish desensitization. In contrast, the effects of wheat germ agglutinin and aniracetam on AMPA receptor desensitization were independent of pH. These results demonstrate that a reduction in the proton sensitivity of receptor desensitization contributes to the mechanism of action of some positive modulators of AMPA receptors.

scholarly journals AMPA receptors and stargazin-like transmembrane AMPA receptor-regulatory proteins mediate hippocampal kainate neurotoxicity

2007 ◽  
Vol 104 (47) ◽  
pp. 18784-18788 ◽  
Author(s):  
S. Tomita ◽  
R. K. Byrd ◽  
N. Rouach ◽  
C. Bellone ◽  
A. Venegas ◽  
...  
Keyword(s):  
Ampa Receptor ◽  
Ampa Receptors ◽  
Regulatory Proteins

scholarly journals Sustained postsynaptic kainate receptor activation downregulates AMPA receptor surface expression and induces hippocampal LTD

2020 ◽  
Author(s):  
Jithin D. Nair ◽  
Ellen Braksator ◽  
Busra P Yucel ◽  
Richard Seager ◽  
Jack R. Mellor ◽  
...  
Keyword(s):  
Ampa Receptor ◽  
Ampa Receptors ◽  
Hippocampal Neurons ◽  
Hippocampal Slices ◽  
Surface Expression ◽  
Receptor Activation ◽  
Kainate Receptors ◽  
Receptor Surface Expression ◽  
Acute Hippocampal Slices

AbstractHere we report that sustained activation of GluK2 subunit-containing kainate receptors leads to AMPA receptor endocytosis and a novel form of long-term depression (KAR-LTDAMPAR) in hippocampal neurons. The KAR-evoked loss of surface AMPA receptors requires KAR channel activity and is occluded by the blockade of PKC or PKA. Moreover, in acute hippocampal slices, kainate invoked LTD of AMPA EPSCs. These data, together with our previously reported KAR-LTPAMPAR, demonstrate that KARs bidirectionally regulate synaptic AMPARs and synaptic plasticity.

scholarly journals The Neuroprotective Role of Origanum syriacum L. and Lavandula dentata L. Essential Oils through Their Effects on AMPA Receptors

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Mohammad Qneibi ◽  
Nidal Jaradat ◽  
Mohammed Hawash ◽  
Abdel Naser Zaid ◽  
Abdel-Razzak Natsheh ◽  
...  
Keyword(s):  
Essential Oils ◽  
Ampa Receptor ◽  
Ampa Receptors ◽  
Neurological Diseases ◽  
Critical Role ◽  
Hek293 Cells ◽  
Gas Chromatography Mass Spectrometry ◽  
Active Components ◽  
Study Results ◽  
Kinetics Of

Lavandula dentata L. and Origanum syriacum L. essential oils have numerous health benefits and properties, such as possessing common components with a variant degree of depressive actions in the central nervous system. We investigated the depressive property of these oils on AMPA receptors, which are responsible for most of the fast-excitatory neurotransmission in the CNS and play a critical role in synaptic plasticity. Since excessive activation of AMPARs has been linked to neurotoxicity leading to various pathologies, we hypothesize that these oils have a neuroprotective role by acting directly on the kinetics of AMPARs. Using Gas Chromatography-Mass Spectrometry (GC/MS) and patch-clamp electrophysiology, the essential oils of L. dentata flowers and O. syriacum leaves were characterized and the whole cell currents were measured with and without the administration of the oils onto HEK293 cells. The current study results showed that the biophysical properties of AMPA receptor subunits showed a decrease in desensitization rate of GluA1 and GluA2 homomers, using O. syriacum, while administering L. dentata oil decreased the desensitization rate of GluA1 and GluA2 homomers, as well as GluA1/2 heteromers. As for the deactivation rate, both oils slowed the deactivation kinetics of all AMPA receptor subunits. Intriguingly, between the two oils, the effect of desensitization and deactivation was of a greater significance for L. dentata oil than O. syriacum. Our data suggest that the two oils contain components that are essential to identify, as those active components underlie the oils’ neuronal depressive properties reported, and to extract them to synthesize a potent neuroprotective drug to treat neurological diseases potentially.

Structures of the AMPA receptor in complex with its auxiliary subunit cornichon

Science ◽  
2019 ◽  
Vol 366 (6470) ◽  
pp. 1259-1263 ◽  
Author(s):  
Terunaga Nakagawa
Keyword(s):  
Ion Channel ◽  
Membrane Topology ◽  
Auxiliary Subunits ◽  
Channel Modulation ◽  
Protein Protein Interaction ◽  
Cryo Electron Microscopy ◽  
Ion Channel Modulation ◽  
Interaction Interface ◽  
Excitatory Neurotransmission ◽  
Membrane Spanning

In the brain, AMPA-type glutamate receptors (AMPARs) form complexes with their auxiliary subunits and mediate the majority of fast excitatory neurotransmission. Signals transduced by these complexes are critical for synaptic plasticity, learning, and memory. The two major categories of AMPAR auxiliary subunits are transmembrane AMPAR regulatory proteins (TARPs) and cornichon homologs (CNIHs); these subunits share little homology and play distinct roles in controlling ion channel gating and trafficking of AMPAR. Here, I report high-resolution cryo–electron microscopy structures of AMPAR in complex with CNIH3. Contrary to its predicted membrane topology, CNIH3 lacks an extracellular domain and instead contains four membrane-spanning helices. The protein-protein interaction interface that dictates channel modulation and the lipids surrounding the complex are revealed. These structures provide insights into the molecular mechanism for ion channel modulation and assembly of AMPAR/CNIH3 complexes.

scholarly journals Functional studies and distribution define a family of transmembrane AMPA receptor regulatory proteins

2003 ◽  
Vol 161 (4) ◽  
pp. 805-816 ◽  
Author(s):  
Susumu Tomita ◽  
Lu Chen ◽  
Yoshimi Kawasaki ◽  
Ronald S. Petralia ◽  
Robert J. Wenthold ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Ampa Receptor ◽  
Ampa Receptors ◽  
Cerebellar Granule Cells ◽  
Surface Expression ◽  
Brain Regions ◽  
Regulatory Proteins ◽  
General Role ◽  
Receptor Complexes

Functional expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in cerebellar granule cells requires stargazin, a member of a large family of four-pass transmembrane proteins. Here, we define a family of transmembrane AMPA receptor regulatory proteins (TARPs), which comprise stargazin, γ-3, γ-4, and γ-8, but not related proteins, that mediate surface expression of AMPA receptors. TARPs exhibit discrete and complementary patterns of expression in both neurons and glia in the developing and mature central nervous system. In brain regions that express multiple isoforms, such as cerebral cortex, TARP–AMPA receptor complexes are strictly segregated, suggesting distinct roles for TARP isoforms. TARPs interact with AMPA receptors at the postsynaptic density, and surface expression of mature AMPA receptors requires a TARP. These studies indicate a general role for TARPs in controlling synaptic AMPA receptors throughout the central nervous system.

scholarly journals Architecture and subunit arrangement of native AMPA receptors elucidated by cryo-EM

Science ◽  
2019 ◽  
Vol 364 (6438) ◽  
pp. 355-362 ◽  
Author(s):  
Yan Zhao ◽  
Shanshuang Chen ◽  
Adam C. Swensen ◽  
Wei-Jun Qian ◽  
Eric Gouaux
Keyword(s):  
Molecular Structure ◽  
Electron Microscopy ◽  
Signal Transduction ◽  
Ligand Binding ◽  
Ampa Receptor ◽  
Ampa Receptors ◽  
Mammalian Brain ◽  
Receptor Complexes ◽  
Cryo Electron Microscopy ◽  
Chemical Synapses

Glutamate-gated AMPA receptors mediate the fast component of excitatory signal transduction at chemical synapses throughout all regions of the mammalian brain. AMPA receptors are tetrameric assemblies composed of four subunits, GluA1–GluA4. Despite decades of study, the subunit composition, subunit arrangement, and molecular structure of native AMPA receptors remain unknown. Here we elucidate the structures of 10 distinct native AMPA receptor complexes by single-particle cryo–electron microscopy (cryo-EM). We find that receptor subunits are arranged nonstochastically, with the GluA2 subunit preferentially occupying the B and D positions of the tetramer and with triheteromeric assemblies comprising a major population of native AMPA receptors. Cryo-EM maps define the structure for S2-M4 linkers between the ligand-binding and transmembrane domains, suggesting how neurotransmitter binding is coupled to ion channel gating.

scholarly journals Control of AMPA receptor activity by the extracellular loops of auxiliary proteins

2017 ◽  
Author(s):  
Irene Riva ◽  
Clarissa Eibl ◽  
Rudolf Volkmer ◽  
Anna L. Carbone ◽  
Andrew J. R. Plested
Keyword(s):  
Ampa Receptor ◽  
Ampa Receptors ◽  
De Novo ◽  
Dominant Role ◽  
Mammalian Brain ◽  
Binding Assays ◽  
Receptor Kinetics ◽  
Receptor Complexes ◽  
Extracellular Loops ◽  
Kinetics Of

AbstractAt synapses throughout the mammalian brain, AMPA receptors form complexes with auxiliary proteins, including TARPs. However, how TARPs modulate AMPA receptor gating remains poorly understood. We built structural models of TARP-AMPA receptor complexes for TARPs γ2 and γ8, combining recent structural studies and de novo structure predictions. These models, combined with peptide binding assays, provide evidence for multiple interactions between GluA2 and variable extracellular loops of TARPs. Substitutions and deletions of these loops had surprisingly rich effects on the kinetics of glutamate-activated currents, without any effect on assembly. Critically, by altering the two interacting loops of γ2 and γ8, we could entirely remove all allosteric modulation of GluA2, without affecting formation of AMPA receptor-TARP complexes. Likewise, substitutions in the linker domains of GluA2 completely removed any effect of Y2 on receptor kinetics, indicating a dominant role for this previously overlooked site proximal to the AMPA receptor channel gate.

AMPA receptor heterogeneity in rat hippocampal neurons revealed by differential sensitivity to cyclothiazide

1996 ◽  
Vol 75 (6) ◽  
pp. 2322-2333 ◽  
Author(s):  
M. W. Fleck ◽  
R. Bahring ◽  
D. K. Patneau ◽  
M. L. Mayer
Keyword(s):  
Ampa Receptor ◽  
Ampa Receptors ◽  
Hippocampal Neurons ◽  
Splice Variants ◽  
Differential Sensitivity ◽  
Stratum Radiatum ◽  
Receptor Subtypes ◽  
Receptor Desensitization ◽  
B Subunits ◽  
Kinetics Of

1. The kinetics of onset of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor desensitization by glutamate, and the extent of attenuation of AMPA receptor desensitization by cyclothiazide, showed pronounced cell-to-cell variation in cultures of rat hippocampal neurons. Cultures prepared from area CA1 stratum radiatum tended to show weaker modulation by cyclothiazide than cultures prepared from the whole hippocampus. 2. Kinetic analysis of concentration jump responses to glutamate revealed multiple populations of receptors with fast (approximately 400 ms), intermediate (approximately 2-4 s), and slow (> 20 s) time constants for recovery from modulation by cyclothiazide. The amplitudes of these components varied widely between cells, suggesting the existence of at least three populations of AMPA receptor subtypes, the relative density of which varied from cell to cell. 3. The complex patterns of sensitivity to cyclothiazide seen in hippocampal neurons could be reconstituted by assembly of recombinant AMPA receptor subunits generated from cDNAs encoding the flip (i) and flop (o) splice variants of the GluR-A and GluR-B subunits. Recovery from modulation by cyclothiazide was slower for GluR-AiBi and GluR-AoBi than for GluR-AiBo and GluR-AoBo. 4. Coexpression of the flip and flop splice variants of GluR-A, in the absence of GluR-B, revealed that heteromeric AMPA receptors with intermediate sensitivity to cyclothiazide, similar to responses observed for the combinations GluR-AoBi or GluR-AiBo, could be generated independently of the presence of the GluR-B subunit. However, recovery from modulation by cyclothiazide was twofold slower for GluR-AiBi than for homomeric GluR-Ai, indicating that the GluR-A and GluR-B subunits are not functionally equivalent in controlling sensitivity to cyclothiazide. 5. These results demonstrate that AMPA receptors expressed in hippocampal neurons are assembled in a variety of subunit and splice variant combinations that might serve as a mechanism to fine-tune the kinetics of synaptic transmission.

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