Brad
| 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 AMPAR 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 AMPARs
- ↑ (59%) AMPAR membrane expression
- Calcium blocking (BAPTA) effect
- ↑ (%) mobile AMPARs
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
- AMPARs vs. NMDAR diffusion
- extrasynaptic: AMPAR > NMDAR (4x)
- synaptic: AMPAR ↔ NMDAR
- synaptic > extrasynaptic (2x ??)
- KCl Neural Stimulation
- ↑ (5x) extrasynaptic diffusion rate AMPAR
- ↔ (%) synaptic diffusion rate AMPAR
- PKC activity (stim by TPA)
- ↑ extrasynaptic diffusion rate AMPAR & NMDAR
- ↑ synaptic diffusion rate AMPAR & NMDAR
2007 Diffusional trapping of GluR1 AMPA receptors by input-specific synaptic activity
Ehlers, Heine, Groc, Lee, Choquet • 2007 • Neuron - PDF
- 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
- very high mobility in extrasynaptic membrane
- intermediate mobility at inactivated synapses
- low mobility at active synapses
- frequently passed through several silenced synapses during recording (Movie S1)
- often exchange from a silenced synapse to a nearby active synapse (Movie S2)
- 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
- To test whether ongoing transmitter activation of glutamate receptors was required for trapping of GluR1
- acutely blocked (for 1-4 hr) basal spontaneous activity with TTX, AP5, and CNQX during imaging
- blocking had no effect on GluR1 mobility at previously active or previously silenced 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
- in active synapses the movement of GluR1 is more confined than at inactive synapses
2007 Interaction between Stargazin and PSD-95 Regulates AMPA Receptor Surface Trafficking
Bats, Groc, Choquet • 2007 • Neuron - PDF
- 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.
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