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{{ExpandBox|2003 Direct imaging of lateral movements of AMPA receptors inside synapses|
{{ExpandBox|2003 Direct imaging of lateral movements of AMPA receptors inside synapses|
{{Article|Tardin, Cognet, Bats, Lounis, Choquet|2003|EMBO - [http://bradleymonk.com/media/Choquet5.pdf PDF]|12970178|Direct imaging of lateral movements of AMPA receptors inside synapses}}
{{Article|Tardin, Cognet, Bats, Lounis, Choquet|2003|EMBO - [http://bradleymonk.com/media/Choquet5.pdf PDF]|12970178|Direct imaging of lateral movements of AMPA (GluR2) receptors inside synapses}}


;Tested effects of glutamate and calcium influx on AMPAR diffusion.
;Tested effects of glutamate and calcium influx on GluR2 diffusion.
*Anti-GluR2 antibodies labeled with Cy5 or Alexa-647
*Anti-GluR2 antibodies labeled with Cy5 or Alexa-647


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;Calcium (induced) influx effect
;Calcium (induced) influx effect
* {{Dn}} (%) mobile AMPARs
* {{Dn}} (%) mobile GluR2
* {{Up}} (59%) AMPAR membrane expression
* {{Up}} (59%) GluR2 membrane expression




;Calcium blocking (BAPTA) effect
;Calcium blocking (BAPTA) effect
* {{Up}} (%) mobile AMPARs
* {{Up}} (%) mobile GluR2
}}<!-- END ARTICLE -->
}}<!-- END ARTICLE -->


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{{Article|Groc L, Heine M, Cognet L, Brickley K, Stephenson FA, Lounis B, Choquet D.|2004|Nature Neuroscience - - [http://bradleymonk.com/media/Choquet6.pdf PDF]|15208630|Differential activity-dependent regulation of the lateral mobilities of AMPA and NMDA receptors}}
{{Article|Groc L, Heine M, Cognet L, Brickley K, Stephenson FA, Lounis B, Choquet D.|2004|Nature Neuroscience - - [http://bradleymonk.com/media/Choquet6.pdf PDF]|15208630|Differential activity-dependent regulation of the lateral mobilities of AMPA and NMDA receptors}}


;AMPARs vs. NMDAR diffusion  
;GluR2 vs. NMDAR-(NR1) diffusion  
*extrasynaptic: AMPAR > NMDAR (4x)
*extrasynaptic: GluR2 > NMDAR (4x)
*synaptic: AMPAR {{Nc}} NMDAR
*synaptic: GluR2 {{Nc}} NMDAR
*synaptic > extrasynaptic (2x ??)
*synaptic > extrasynaptic (2x ??)


;KCl Neural Stimulation:
;KCl Neural Stimulation:
*{{Up}} (5x) extrasynaptic diffusion rate AMPAR
*{{Up}} (5x) extrasynaptic diffusion rate GluR2
*{{Nc}} (%) synaptic diffusion rate AMPAR
*{{Nc}} (%) synaptic diffusion rate GluR2


;PKC activity (stim by TPA):  
;PKC activity (stim by TPA):  
*{{Up}} extrasynaptic diffusion rate AMPAR & NMDAR
*{{Up}} extrasynaptic diffusion rate GluR2 & NMDAR
*{{Up}} synaptic diffusion rate AMPAR & NMDAR
*{{Up}} synaptic diffusion rate GluR2 & NMDAR


[[File:Choquet 2004b.png|thumb|left|500px|
[[File:Choquet 2004b.png|thumb|left|500px|
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{{Article|Ehlers, Heine, Groc, Lee, Choquet|2007|Neuron - [http://bradleymonk.com/media/Choquet2007B.pdf PDF]|17481397|Diffusional trapping of GluR1 AMPA receptors by input-specific synaptic activity}}
{{Article|Ehlers, Heine, Groc, Lee, Choquet|2007|Neuron - [http://bradleymonk.com/media/Choquet2007B.pdf PDF]|17481397|Diffusional trapping of GluR1 AMPA receptors by input-specific synaptic activity}}


;Results
*'''silenced synapses had:'''
**50% less GluR1 [[AMPA receptors]] than nearby active synapses
**no changes in [[PSD-95]] family proteins
**no change in presynaptic abundance of VGLUT1 or bassoon
**no difference in [[PSD-95]], Shank, or bassoon puncta size


*'''GluR1-QDots'''
;silenced synapses (compared to active synapses)
**very high mobility in extrasynaptic membrane
* {{Dn}} (50%) GluR1
**intermediate mobility at inactivated synapses
* {{Nc}} PSD-95
**low mobility at active synapses
* {{Nc}} presynaptic VGLUT1
**frequently passed through several silenced synapses during recording (Movie S1)
* {{Nc}} presynaptic bassoon
**often exchange from a silenced synapse to a nearby active synapse (Movie S2)
* {{Nc}} puncta size of PSD-95 Shank bassoon
**rarely exchanged from an active synapse to inactive synapse (2 of 1700)
**at inactivated synapses, 76.1% of GluR1-QDs present at the synapse departed the synapse within a 60 s imaging period
**at nearby active synapses, only 21.4% of GluR1-QDs exited the synapse within a 60 s imaging period


*'''Acute Blocking of Active Synapses'''
;GluR1 QDots diffusion rate
**To test whether ongoing transmitter activation of glutamate receptors was required for trapping of GluR1
* high - extrasynaptic
**acutely blocked (for 1-4 hr) basal spontaneous activity with TTX, AP5, and CNQX during imaging
* medium - inactivated synapses
**blocking had no effect on GluR1 mobility at previously active or previously silenced synapses
* low - active synapses
***synapses active before TTX/AP5/CNQX continued to exhibit decreased GluR1 mobility relative to synapses chronically silenced by tetanus toxin
**results demonstrate the diffusional trapping of GluR1 at active synapses not acute effect of basal spontaneous activity, but rather a longer-term change in synapse organization


*'''Spontaneous Activity Confines GluR1 Intrasynaptic Movement'''
;GluR1 QDots features
**in active synapses the movement of GluR1 is more confined than at inactive synapses
* often passed through silenced synapses
[[File:Choquet2007B1.png|thumb|left|300px|(D) Single GluR1-QDs explore large areas within inactive synapses. Shown are five synaptic regions defined as a set of connected pixels obtained using object segmentation by wavelet transform. Each pixel was divided into 0.0016 mm2 subdomains and coded based on the presence (pink) or absence (white) of the GluR1-QD at any time during the imaging period as defined by the centroid of a 2D Gaussian function fit to the GluR1-QD fluorescent signal (see Experimental Procedures for details). Coded areas at each synaptic region represent the trajectory of one GluR1-QD. Scale bar, 0.2 mm. (E) GluR1 explores only small subregions within active synapses. Objects, color code, and scale bar as in (D)]]
* often moved from silenced to active synapse
* rarely (2 of 1700) moved from active to silenced synapse
* often (76.1%) exited inactive synapse (60 s period)
* rarely (21.4%) exited active synapse (60 s period)
 
;GluR1 QDots diffusion rate after synaptic reversal
* {{Nc}} at previously active synapses
* {{Nc}} at previously silenced synapses
 
 
[[File:Choquet2007B1.png|thumb|left|400px|
<b>Confinement of GluR1 in synapses</b><br>
* more confined at active vs inactive synapses
]]




Revision as of 20:19, 9 July 2013

Malinow Molecular Methods Quantum Dots Choquet AMPAR


Study Timeline - PubMed



Summary

2003 Direct imaging of lateral movements of AMPA receptors inside synapses

Tardin, Cognet, Bats, Lounis, Choquet • 2003 • EMBO - PDF

Tested effects of glutamate and calcium influx on GluR2 diffusion.
  • Anti-GluR2 antibodies labeled with Cy5 or Alexa-647


Glutamate (100 uM) effect on GluR2
  • ↑ diffusion rate
  • ↑ (85%) endocytosis (within 15 min)
  • ↑ (55%) diffusion within synapses
  • ↔ diffusion rate non-synaptic
  • ↓ (30%) completely immobile receptors


Calcium (induced) influx effect
  • ↓ (%) mobile GluR2
  • ↑ (59%) GluR2 membrane expression


Calcium blocking (BAPTA) effect
  • ↑ (%) mobile GluR2


2004 Differential activity-dependent regulation of the lateral mobilities of AMPA and NMDA receptors

Groc L, Heine M, Cognet L, Brickley K, Stephenson FA, Lounis B, Choquet D. • 2004 • Nature Neuroscience - - PDF

GluR2 vs. NMDAR-(NR1) diffusion
  • extrasynaptic: GluR2 > NMDAR (4x)
  • synaptic: GluR2 ↔ NMDAR
  • synaptic > extrasynaptic (2x ??)
KCl Neural Stimulation
  • ↑ (5x) extrasynaptic diffusion rate GluR2
  • ↔ (%) synaptic diffusion rate GluR2
PKC activity (stim by TPA)
  • ↑ extrasynaptic diffusion rate GluR2 & NMDAR
  • ↑ synaptic diffusion rate GluR2 & NMDAR
Error creating thumbnail: File missing
* TTX - block neural activity
* KCl - envoke neural activity
* TPA - stimulate PKC


2007 Diffusional trapping of GluR1 AMPA receptors by input-specific synaptic activity

Ehlers, Heine, Groc, Lee, Choquet • 2007 • Neuron - PDF


silenced synapses (compared to active synapses)
  • ↓ (50%) GluR1
  • ↔ PSD-95
  • ↔ presynaptic VGLUT1
  • ↔ presynaptic bassoon
  • ↔ puncta size of PSD-95 Shank bassoon
GluR1 QDots diffusion rate
  • high - extrasynaptic
  • medium - inactivated synapses
  • low - active synapses
GluR1 QDots features
  • often passed through silenced synapses
  • often moved from silenced to active synapse
  • rarely (2 of 1700) moved from active to silenced synapse
  • often (76.1%) exited inactive synapse (60 s period)
  • rarely (21.4%) exited active synapse (60 s period)
GluR1 QDots diffusion rate after synaptic reversal
  • ↔ at previously active synapses
  • ↔ at previously silenced synapses


Error creating thumbnail: File missing
Confinement of GluR1 in synapses
* more confined at active vs inactive synapses



2007 Interaction between Stargazin and PSD-95 Regulates AMPA Receptor Surface Trafficking

Notes
  • Quantum Dot
  • FRAP
  • Live hippocampal neurons
  • exchange of AMPAR by lateral diffusion between extrasynaptic and synaptic sites mostly depends on the interaction of Stargazin with PSD-95 and not upon the GluR2 AMPAR subunit C terminus.
  • Disruption of interactions between Stargazin and PSD-95 strongly increases AMPAR surface diffusion, preventing AMPAR accumulation at postsynaptic sites.
  • AMPARs and Stargazin diffuse as complexes in and out synapses.






{{Article|Author|Year|Journal - [http://bradleymonk.com/media/Choquet1.pdf PDF]|15749166|Title}}
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