scholarly journals Mechanisms of postsynaptic localization of AMPA-type glutamate receptors and their regulation during long-term potentiation

2019 ◽  
Vol 12 (562) ◽  
pp. eaar6889 ◽  
Author(s):  
Olivia R. Buonarati ◽  
Erik A. Hammes ◽  
Jake F. Watson ◽  
Ingo H. Greger ◽  
Johannes W. Hell
Keyword(s):  
Glutamate Receptors ◽  
Molecular Mechanisms ◽  
Glutamate Release ◽  
Regulatory Protein ◽  
Long Term Potentiation ◽  
Excitatory Neurotransmitter ◽  
Recycling Endosomes ◽  
Amino Terminal ◽  
Term Potentiation ◽  
Amino Terminal Domain

l-Glutamate is the main excitatory neurotransmitter in the brain, with postsynaptic responses to its release predominantly mediated by AMPA-type glutamate receptors (AMPARs). A critical component of synaptic plasticity involves changes in the number of responding postsynaptic receptors, which are dynamically recruited to and anchored at postsynaptic sites. Emerging findings continue to shed new light on molecular mechanisms that mediate AMPAR postsynaptic trafficking and localization. Accordingly, unconventional secretory trafficking of AMPARs occurs in dendrites, from the endoplasmic reticulum (ER) through the ER-Golgi intermediary compartment directly to recycling endosomes, independent of the Golgi apparatus. Upon exocytosis, AMPARs diffuse in the plasma membrane to reach the postsynaptic site, where they are trapped to contribute to transmission. This trapping occurs through a combination of both intracellular interactions, such as TARP (transmembrane AMPAR regulatory protein) binding to α-actinin–stabilized PSD-95, and extracellular interactions through the receptor amino-terminal domain. These anchoring mechanisms may facilitate precise receptor positioning with respect to glutamate release sites to enable efficient synaptic transmission.

scholarly journals Subunit-specific role for the amino-terminal domain of AMPA receptors in synaptic targeting

2017 ◽  
Vol 114 (27) ◽  
pp. 7136-7141 ◽  
Author(s):  
Javier Díaz-Alonso ◽  
Yujiao J. Sun ◽  
Adam J. Granger ◽  
Jonathan M. Levy ◽  
Sabine M. Blankenship ◽  
...  
Keyword(s):  
Ampa Receptors ◽  
Critical Role ◽  
Long Term Potentiation ◽  
Masking Effect ◽  
Synaptic Targeting ◽  
Amino Terminal ◽  
Terminal Domain ◽  
Term Potentiation ◽  
Amino Terminal Domain

The amino-terminal domain (ATD) of AMPA receptors (AMPARs) accounts for approximately 50% of the protein, yet its functional role, if any, remains a mystery. We have discovered that the translocation of surface GluA1, but not GluA2, AMPAR subunits to the synapse requires the ATD. GluA1A2 heteromers in which the ATD of GluA1 is absent fail to translocate, establishing a critical role of the ATD of GluA1. Inserting GFP into the ATD interferes with the constitutive synaptic trafficking of GluA1, but not GluA2, mimicking the deletion of the ATD. Remarkably, long-term potentiation (LTP) can override the masking effect of the GFP tag. GluA1, but not GluA2, lacking the ATD fails to show LTP. These findings uncover a role for the ATD in subunit-specific synaptic trafficking of AMPARs, both constitutively and during plasticity. How LTP, induced postsynaptically, engages these extracellular trafficking motifs and what specific cleft proteins participate in the process remain to be elucidated.

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 Optical monitoring of glutamate release at multiple synapses in situ detects changes following LTP induction

2019 ◽  
Author(s):  
Olga Kopach ◽  
Kaiyu Zheng ◽  
Dmitri Rusakov
Keyword(s):  
Optical Sensors ◽  
Glutamate Release ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Excitatory Neurotransmitter ◽  
Two Photon ◽  
Photon Excitation ◽  
Term Potentiation ◽  
Before And After ◽  
Acute Hippocampal Slices

Abstract Information processing and memory formation in the brain relies on release of the main excitatory neurotransmitter glutamate from presynaptic axonal specialisations. The classical Hebbian paradigm of synaptic memory, long-term potentiation (LTP) of transmission, has been widely associated with an increase in the postsynaptic receptor current. Whether and to what degree LTP induction also enhances presynaptic glutamate release has been the subject of debate. Here, we took advantage of the recently developed genetically encoded optical sensors of glutamate (iGluSnFr) to monitor its release at CA3-CA1 synapses in acute hippocampal slices, before and after the induction of LTP. We attempted to trace release events at multiple synapses simultaneously, by using two-photon excitation imaging in fast frame-scanning mode. We thus detected a significant increase in the average glutamate signal during potentiation, which lasted for up to 90 min.

scholarly journals Optical monitoring of glutamate release at multiple synapses in situ detects changes following LTP induction

2020 ◽  
Author(s):  
Olga Kopach ◽  
Kaiyu Zheng ◽  
Dmitri Rusakov
Keyword(s):  
Optical Sensors ◽  
Glutamate Release ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Excitatory Neurotransmitter ◽  
Glutamate Binding ◽  
Photon Excitation ◽  
Term Potentiation ◽  
Before And After ◽  
Acute Hippocampal Slices

Abstract Information processing and memory formation in the brain relies on release of the main excitatory neurotransmitter glutamate from presynaptic axonal specialisations. The classical Hebbian paradigm of synaptic memory, long-term potentiation (LTP) of transmission, has been widely associated with an increase in the postsynaptic receptor current. Whether and to what degree LTP induction also enhances presynaptic glutamate release has been the subject of debate. Here, we took advantage of the recently developed genetically encoded optical sensors of glutamate (iGluSnFR) to monitor its release at CA3-CA1 synapses in acute hippocampal slices, before and after the induction of LTP. We attempted to trace release events at multiple synapses simultaneously, by using two-photon excitation imaging in fast frame-scanning mode. We thus detected a significant increase in the average iGluSnFR signal during potentiation, which lasted for up to 90 min. This increase may reflect an increased amount of released glutamate or, alternatively, reduced glutamate binding to high-affinity glutamate transporters that compete with iGluSnFR.

scholarly journals Activity-dependent regulation of synaptic strength by PSD-95 in CA1 neurons

2012 ◽  
Vol 107 (4) ◽  
pp. 1058-1066 ◽  
Author(s):  
Peng Zhang ◽  
John E. Lisman
Keyword(s):  
Glutamate Receptors ◽  
Metabotropic Glutamate Receptors ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Synaptic Strength ◽  
Ca1 Neurons ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Term Potentiation ◽  
Activity Dependent

CaMKII and PSD-95 are the two most abundant postsynaptic proteins in the postsynaptic density (PSD). Overexpression of either can dramatically increase synaptic strength and saturate long-term potentiation (LTP). To do so, CaMKII must be activated, but the same is not true for PSD-95; expressing wild-type PSD-95 is sufficient. This raises the question of whether PSD-95's effects are simply an equilibrium process [increasing the number of AMPA receptor (AMPAR) slots] or whether activity is somehow involved. To examine this question, we blocked activity in cultured hippocampal slices with TTX and found that the effects of PSD-95 overexpression were greatly reduced. We next studied the type of receptors involved. The effects of PSD-95 were prevented by antagonists of group I metabotropic glutamate receptors (mGluRs) but not by antagonists of ionotropic glutamate receptors. The inhibition of PSD-95-induced strengthening was not simply a result of inhibition of PSD-95 synthesis. To understand the mechanisms involved, we tested the role of CaMKII. Overexpression of a CaMKII inhibitor, CN19, greatly reduced the effect of PSD-95. We conclude that PSD-95 cannot itself increase synaptic strength simply by increasing the number of AMPAR slots; rather, PSD-95's effects on synaptic strength require an activity-dependent process involving mGluR and CaMKII.

scholarly journals Altered Short-Term Synaptic Plasticity in Mice Lacking the Metabotropic Glutamate Receptor mGlu7

2002 ◽  
Vol 2 ◽  
pp. 730-737 ◽  
Author(s):  
Trevor J. Bushell ◽  
Gilles Sansig ◽  
Valerie J. Collett ◽  
Herman van der Putten ◽  
Graham L. Collingridge
Keyword(s):  
Synaptic Plasticity ◽  
Molecular Mechanisms ◽  
Pyramidal Neurons ◽  
Metabotropic Glutamate Receptor ◽  
Long Term Potentiation ◽  
Short Term ◽  
Metabotropic Glutamate ◽  
Term Potentiation ◽  
Commissural Pathway ◽  
Frequency Facilitation

Eight subtypes of metabotropic glutamate (mGlu) receptors have been identified of which two, mGlu5 and mGlu7, are highly expressed at synapses made between CA3 and CA1 pyramidal neurons in the hippocampus. This input, the Schaffer collateral-commissural pathway, displays robust long-term potentiation (LTP), a process believed to utilise molecular mechanisms that are key processes involved in the synaptic basis of learning and memory. To investigate the possible function in LTP of mGlu7 receptors, a subtype for which no specific antagonists exist, we generated a mouse lacking this receptor, by homologous recombination. We found that LTP could be induced in mGlu7-/- mice and that once the potentiation had reached a stable level there was no difference in the magnitude of LTP between mGlu7-/- mice and their littermate controls. However, the initial decremental phase of LTP, known as short-term potentiation (STP), was greatly attenuated in the mGlu7-/- mouse. In addition, there was less frequency facilitation during, and less post-tetanic potentiation following, a high frequency train in the mGlu7-/- mouse. These results show that the absence of mGlu7 receptors results in alterations in short-term synaptic plasticity in the hippocampus.

Sign in / Sign up

Export Citation Format

Share Document