scholarly journals Molecular Characterization of AMPA-Receptor-Containing Vesicles

2021 ◽  
Vol 14 ◽  
Author(s):  
John Jacob Peters ◽  
Jeremy Leitz ◽  
Juan A. Oses-Prieto ◽  
Alma L. Burlingame ◽  
Axel T. Brunger
Keyword(s):  
Ampa Receptors ◽  
Molecular Mechanisms ◽  
Small Diameter ◽  
Long Term Potentiation ◽  
Postsynaptic Membrane ◽  
Snare Complex ◽  
Calcium Sensors ◽  
Term Potentiation ◽  
Liquid Chromatography Tandem Mass ◽  
Ampar Trafficking

Regulated delivery of AMPA receptors (AMPARs) to the postsynaptic membrane is an essential step in synaptic strength modification, and in particular, long-term potentiation (LTP). While LTP has been extensively studied using electrophysiology and light microscopy, several questions regarding the molecular mechanisms of AMPAR delivery via trafficking vesicles remain outstanding, including the gross molecular make up of AMPAR trafficking organelles and identification and location of calcium sensors required for SNARE complex-dependent membrane fusion of such trafficking vesicles with the plasma membrane. Here, we isolated AMPA-containing vesicles (ACVs) from whole mouse brains via immunoisolation and characterized them using immunoelectron microscopy, immunoblotting, and liquid chromatography–tandem mass spectrometry (LC–MS/MS). We identified several proteins on ACVs that were previously found to play a role in AMPAR trafficking, including synaptobrevin-2, Rabs, the SM protein Munc18-1, the calcium-sensor synaptotagmin-1, as well as several new candidates, including synaptophysin and synaptogyrin on ACV membranes. Additionally, we identified two populations of ACVs based on size and molecular composition: small-diameter, synaptobrevin-2- and GluA1-containing ACVs, and larger transferrin- receptor-, GluA1-, GluA2-, and GluA3-containing ACVs. The small-diameter population of ACVs may represent a fusion-capable population of vesicles due to the presence of synaptobrevin-2. Because the fusion of ACVs may be a requisite of LTP, this population could represent trafficking vesicles related to LTP.

scholarly journals Molecular characterization of AMPA receptor trafficking vesicles

2021 ◽  
Author(s):  
John Jacob Peters ◽  
Jeremy Leitz ◽  
Juan A Oses-Prieto ◽  
Alma L Burlingame ◽  
Axel T Brunger
Keyword(s):  
Ampa Receptors ◽  
Molecular Mechanisms ◽  
Small Diameter ◽  
Long Term Potentiation ◽  
Synaptic Strength ◽  
Postsynaptic Membrane ◽  
Snare Complex ◽  
Calcium Sensors ◽  
Liquid Chromatography Tandem Mass ◽  
Ampar Trafficking

Regulated delivery of AMPA receptors (AMPARs) to the postsynaptic membrane is an essential step in synaptic strength modification, and in particular, long-term potentiation (LTP). While LTP has been extensively studied using electrophysiology and light microscopy, several questions regarding the molecular mechanisms of AMPAR delivery via trafficking vesicles remain outstanding, including the gross molecular make up of AMPAR trafficking organelles and identification and location of calcium sensors required for SNARE complex-dependent membrane fusion of such trafficking vesicles with the plasma membrane. Here, we isolated AMPAR trafficking vesicles (ATVs) from whole mouse brains via immunoprecipitation and characterized them using immunoelectron microscopy, immunoblotting, and liquid chromatography tandem mass spectrometry (LC-MS/MS). We identified several proteins on ATVs that were previously found to play a role in AMPAR trafficking, including SNARES (including synaptobrevin 2), Rabs, the SM protein Munc18-1, a calcium-sensor (synaptotagmin-1), as well as several new markers, including synaptophysin and synaptogyrin on ATV membranes. Additionally, we identified two populations of ATVs based on size and molecular composition: small-diameter, synaptobrevin-2- and GluA1-containing ATVs and larger transferrin-receptor-, GluA1-, GluA2-, GluA3-containing ATVs. The smaller population of ATVs likely represents a trafficking vesicle whose fusion is essential for LTP. These findings reveal the important role of AMPAR sorting into fusion-competent trafficking vesicles that are implicated in synaptic strength modification and reveal candidates of putative effectors and regulators of AMPAR trafficking.

scholarly journals AMPAR trafficking dependent LTP initiates cortical remapping and adaptive behaviors during sensory experience

2020 ◽  
Author(s):  
Tiago Campelo ◽  
Elisabete Augusto ◽  
Nicolas Chenouard ◽  
Aron de Miranda ◽  
Vladimir Kouskoff ◽  
...  
Keyword(s):  
Ampa Receptors ◽  
Barrel Cortex ◽  
Cortical Plasticity ◽  
Long Term Potentiation ◽  
Sensory Function ◽  
Term Potentiation ◽  
Ampar Trafficking ◽  
Sensory Responses ◽  
Cortical Regions

AbstractCortical plasticity improves behaviors and helps recover lost functions after injury by adapting neuronal computations. However, the underlying synaptic and circuit mechanisms remain unclear. In mice, we found that trimming all but one whisker enhances sensory responses from the spared whisker in the somatosensory barrel cortex and occludes whisker-mediated long-term potentiation (w-LTP) in vivo. In addition, whisking-dependent behaviors that are initially impaired by single whisker experience (SWE) rapidly recover when associated cortical regions remap. Blocking the surface diffusion of AMPA receptors (AMPARs) suppresses the expression of w-LTP in naïve mice with all whiskers intact, demonstrating that physiologically induced LTP in vivo requires AMPARs trafficking. We used this approach to demonstrate that w-LTP is required for SWE-mediated strengthening of synaptic inputs and initiates the recovery of previously learned skills during the early phases of SWE. Taken together, our data reveal that w-LTP mediates cortical remapping and behavioral improvement upon partial sensory deafferentation and demonstrates that restoration of sensory function after peripheral injury can be manipulated.

scholarly journals Mechanism underlying hippocampal long-term potentiation and depression based on competition between endocytosis and exocytosis of AMPA receptors

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tomonari Sumi ◽  
Kouji Harada
Keyword(s):  
Ampa Receptors ◽  
Molecular Motor ◽  
Signal Transmission ◽  
Long Term Potentiation ◽  
Synaptic Membranes ◽  
Recycling Endosome ◽  
Independent Manner ◽  
Term Potentiation ◽  
Ampar Trafficking

Abstract N-methyl-D-aspartate (NMDA) receptor-dependent long-term potentiation (LTP) and long-term depression (LTD) of signal transmission form neural circuits and thus are thought to underlie learning and memory. These mechanisms are mediated by AMPA receptor (AMPAR) trafficking in postsynaptic neurons. However, the regulatory mechanism of bidirectional plasticity at excitatory synapses remains unclear. We present a network model of AMPAR trafficking for adult hippocampal pyramidal neurons, which reproduces both LTP and LTD. We show that the induction of both LTP and LTD is regulated by the competition between exocytosis and endocytosis of AMPARs, which are mediated by the calcium-sensors synaptotagmin 1/7 (Syt1/7) and protein interacting with C-kinase 1 (PICK1), respectively. Our result indicates that recycling endosomes containing AMPAR are always ready for Syt1/7-dependent exocytosis of AMPAR at peri-synaptic/synaptic membranes. This is because molecular motor myosin Vb constitutively transports the recycling endosome toward the membrane in a Ca2+-independent manner.

scholarly journals p97 regulates GluA1 homomeric AMPA receptor formation and plasma membrane expression

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yuan Ge ◽  
Meng Tian ◽  
Lidong Liu ◽  
Tak Pan Wong ◽  
Bo Gong ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Long Term Potentiation ◽  
Postsynaptic Membrane ◽  
Mammalian Brain ◽  
Membrane Expression ◽  
Term Potentiation ◽  
Hippocampal Ca1 ◽  
Plasma Membrane Expression

Abstract The α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid subtype glutamate receptors (AMPARs) mediate the fast excitatory synaptic transmission in the mammalian brain and are important for synaptic plasticity. In particular, the rapid insertion of the GluA1 homomeric (GluA1-homo) AMPARs into the postsynaptic membrane is considered to be critical in the expression of hippocampal CA1 long-term potentiation (LTP), which is important for certain forms of learning and memory. However, how the formation and trafficking of GluA1-homo AMPARs are regulated remains poorly understood. Here, we report that p97 specifically interacts with and promotes the formation of GluA1-homo AMPARs. The association with p97 retains GluA1-homo AMPARs in the intracellular compartment under basal conditions, and its dissociation allows GluA1-homo AMPARs to be rapidly inserted into the postsynaptic membrane shortly after LTP induction. Thus, our results shed lights into the molecular mechanisms by which p97 regulates GluA1-homo AMPARs formation and trafficking, thereby playing a critical role in mediating synaptic plasticity.

scholarly journals The amino-terminal domain of GluA1 mediates LTP maintenance via interaction with neuroplastin-65

2021 ◽  
Vol 118 (9) ◽  
pp. e2019194118
Author(s):  
Chao-Hua Jiang ◽  
Mengping Wei ◽  
Chen Zhang ◽  
Yun Stone Shi
Keyword(s):  
Ampa Receptors ◽  
Cell Adhesion Molecule ◽  
Long Term Potentiation ◽  
Postsynaptic Membrane ◽  
Amino Terminal ◽  
Terminal Domain ◽  
Term Potentiation ◽  
Amino Terminal Domain ◽  
Mutant Forms

Long-term potentiation (LTP) has long been considered as an important cellular mechanism for learning and memory. LTP expression involves NMDA receptor-dependent synaptic insertion of AMPA receptors (AMPARs). However, how AMPARs are recruited and anchored at the postsynaptic membrane during LTP remains largely unknown. In this study, using CRISPR/Cas9 to delete the endogenous AMPARs and replace them with the mutant forms in single neurons, we have found that the amino-terminal domain (ATD) of GluA1 is required for LTP maintenance. Moreover, we show that GluA1 ATD directly interacts with the cell adhesion molecule neuroplastin-65 (Np65). Neurons lacking Np65 exhibit severely impaired LTP maintenance, and Np65 deletion prevents GluA1 from rescuing LTP in AMPARs-deleted neurons. Thus, our study reveals an essential role for GluA1/Np65 binding in anchoring AMPARs at the postsynaptic membrane during LTP.

scholarly journals A Multisubcellular Compartment Model of AMPA Receptor Trafficking for Neuromodulation of Hebbian Synaptic Plasticity

2021 ◽  
Vol 13 ◽  
Author(s):  
Stefan Mihalas ◽  
Alvaro Ardiles ◽  
Kaiwen He ◽  
Adrian Palacios ◽  
Alfredo Kirkwood
Keyword(s):  
Synaptic Plasticity ◽  
Ampa Receptors ◽  
Compartment Model ◽  
Long Term Potentiation ◽  
Reverse Direction ◽  
Term Potentiation ◽  
Simple Kinetic Model ◽  
Ampar Trafficking ◽  
Central Synapses

Neuromodulation can profoundly impact the gain and polarity of postsynaptic changes in Hebbian synaptic plasticity. An emerging pattern observed in multiple central synapses is a pull–push type of control in which activation of receptors coupled to the G-protein Gs promote long-term potentiation (LTP) at the expense of long-term depression (LTD), whereas receptors coupled to Gq promote LTD at the expense of LTP. Notably, coactivation of both Gs- and Gq-coupled receptors enhances the gain of both LTP and LTD. To account for these observations, we propose a simple kinetic model in which AMPA receptors (AMPARs) are trafficked between multiple subcompartments in and around the postsynaptic spine. In the model AMPARs in the postsynaptic density compartment (PSD) are the primary contributors to synaptic conductance. During LTP induction, AMPARs are trafficked to the PSD primarily from a relatively small perisynaptic (peri-PSD) compartment. Gs-coupled receptors promote LTP by replenishing peri-PSD through increased AMPAR exocytosis from a pool of endocytic AMPAR. During LTD induction AMPARs are trafficked in the reverse direction, from the PSD to the peri-PSD compartment, and Gq-coupled receptors promote LTD by clearing the peri-PSD compartment through increased AMPAR endocytosis. We claim that the model not only captures essential features of the pull–push neuromodulation of synaptic plasticity, but it is also consistent with other actions of neuromodulators observed in slice experiments and is compatible with the current understanding of AMPAR trafficking.

scholarly journals Network compensation of cyclic GMP-dependent protein kinase II knockout in the hippocampus by Ca2+-permeable AMPA receptors

2015 ◽  
Vol 112 (10) ◽  
pp. 3122-3127 ◽  
Author(s):  
Seonil Kim ◽  
Roseann F. Titcombe ◽  
Hong Zhang ◽  
Latika Khatri ◽  
Hiwot K. Girma ◽  
...  
Keyword(s):  
Ampa Receptors ◽  
Hippocampal Neurons ◽  
Gene Knockout ◽  
Long Term Potentiation ◽  
Compensatory Response ◽  
Functional Compensation ◽  
Term Potentiation ◽  
Ampar Trafficking ◽  
Dependent Protein ◽  
A Subunit

Gene knockout (KO) does not always result in phenotypic changes, possibly due to mechanisms of functional compensation. We have studied mice lacking cGMP-dependent kinase II (cGKII), which phosphorylates GluA1, a subunit of AMPA receptors (AMPARs), and promotes hippocampal long-term potentiation (LTP) through AMPAR trafficking. Acute cGKII inhibition significantly reduces LTP, whereas cGKII KO mice show no LTP impairment. Significantly, the closely related kinase, cGKI, does not compensate for cGKII KO. Here, we describe a previously unidentified pathway in the KO hippocampus that provides functional compensation for the LTP impairment observed when cGKII is acutely inhibited. We found that in cultured cGKII KO hippocampal neurons, cGKII-dependent phosphorylation of inositol 1,4,5-trisphosphate receptors was decreased, reducing cytoplasmic Ca2+ signals. This led to a reduction of calcineurin activity, thereby stabilizing GluA1 phosphorylation and promoting synaptic expression of Ca2+-permeable AMPARs, which in turn induced a previously unidentified form of LTP as a compensatory response in the KO hippocampus. Calcineurin-dependent Ca2+-permeable AMPAR expression observed here is also used during activity-dependent homeostatic synaptic plasticity. Thus, a homeostatic mechanism used during activity reduction provides functional compensation for gene KO in the cGKII KO hippocampus.

scholarly journals GRIP1 regulates synaptic plasticity and learning and memory

2020 ◽  
Vol 117 (40) ◽  
pp. 25085-25091
Author(s):  
Han L. Tan ◽  
Shu-Ling Chiu ◽  
Qianwen Zhu ◽  
Richard L. Huganir
Keyword(s):  
Synaptic Plasticity ◽  
Learning And Memory ◽  
Molecular Mechanisms ◽  
Long Term Potentiation ◽  
Postsynaptic Membrane ◽  
Interacting Protein ◽  
Synaptic Targeting ◽  
Brain Functions ◽  
Ampar Trafficking

Hebbian plasticity is a key mechanism for higher brain functions, such as learning and memory. This form of synaptic plasticity primarily involves the regulation of synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) abundance and properties, whereby AMPARs are inserted into synapses during long-term potentiation (LTP) or removed during long-term depression (LTD). The molecular mechanisms underlying AMPAR trafficking remain elusive, however. Here we show that glutamate receptor interacting protein 1 (GRIP1), an AMPAR-binding protein shown to regulate the trafficking and synaptic targeting of AMPARs, is required for LTP and learning and memory. GRIP1 is recruited into synapses during LTP, and deletion of Grip1 in neurons blocks synaptic AMPAR accumulation induced by glycine-mediated depolarization. In addition, Grip1 knockout mice exhibit impaired hippocampal LTP, as well as deficits in learning and memory. Mechanistically, we find that phosphorylation of serine-880 of the GluA2 AMPAR subunit (GluA2-S880) is decreased while phosphorylation of tyrosine-876 on GluA2 (GluA2-Y876) is elevated during chemically induced LTP. This enhances the strength of the GRIP1–AMPAR association and, subsequently, the insertion of AMPARs into the postsynaptic membrane. Together, these results demonstrate an essential role of GRIP1 in regulating AMPAR trafficking during synaptic plasticity and learning and memory.

scholarly journals PKA drives an increase in AMPA receptor unitary conductance during LTP in the hippocampus

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pojeong Park ◽  
John Georgiou ◽  
Thomas M. Sanderson ◽  
Kwang-Hee Ko ◽  
Heather Kang ◽  
...  
Keyword(s):  
Ampa Receptors ◽  
Single Channel ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Theta Burst Stimulation ◽  
Term Potentiation ◽  
Hippocampal Ca1 ◽  
Necessary And Sufficient ◽  
Theta Burst

AbstractLong-term potentiation (LTP) at hippocampal CA1 synapses can be expressed by an increase either in the number (N) of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors or in their single channel conductance (γ). Here, we have established how these distinct synaptic processes contribute to the expression of LTP in hippocampal slices obtained from young adult rodents. LTP induced by compressed theta burst stimulation (TBS), with a 10 s inter-episode interval, involves purely an increase in N (LTPN). In contrast, either a spaced TBS, with a 10 min inter-episode interval, or a single TBS, delivered when PKA is activated, results in LTP that is associated with a transient increase in γ (LTPγ), caused by the insertion of calcium-permeable (CP)-AMPA receptors. Activation of CaMKII is necessary and sufficient for LTPN whilst PKA is additionally required for LTPγ. Thus, two mechanistically distinct forms of LTP co-exist at these synapses.

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