Ultrafast glutamate sensors resolve high-frequency release at Schaffer collateral synapses
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Ultrafast glutamate sensors resolve high-frequency release at Schaffer collateral synapses. / Helassa, Nordine; Dürst, Céline D; Coates, Catherine; Kerruth, Silke; Arif, Urwa; Schulze, Christian; Wiegert, J Simon; Geeves, Michael; Oertner, Thomas G; Török, Katalin.
in: P NATL ACAD SCI USA, Jahrgang 115, Nr. 21, 22.05.2018, S. 5594-5599.Publikationen: SCORING: Beitrag in Fachzeitschrift/Zeitung › SCORING: Zeitschriftenaufsatz › Forschung › Begutachtung
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T1 - Ultrafast glutamate sensors resolve high-frequency release at Schaffer collateral synapses
AU - Helassa, Nordine
AU - Dürst, Céline D
AU - Coates, Catherine
AU - Kerruth, Silke
AU - Arif, Urwa
AU - Schulze, Christian
AU - Wiegert, J Simon
AU - Geeves, Michael
AU - Oertner, Thomas G
AU - Török, Katalin
N1 - Copyright © 2018 the Author(s). Published by PNAS.
PY - 2018/5/22
Y1 - 2018/5/22
N2 - Glutamatergic synapses display a rich repertoire of plasticity mechanisms on many different time scales, involving dynamic changes in the efficacy of transmitter release as well as changes in the number and function of postsynaptic glutamate receptors. The genetically encoded glutamate sensor iGluSnFR enables visualization of glutamate release from presynaptic terminals at frequencies up to ∼10 Hz. However, to resolve glutamate dynamics during high-frequency bursts, faster indicators are required. Here, we report the development of fast (iGlu f ) and ultrafast (iGlu u ) variants with comparable brightness but increased Kd for glutamate (137 μM and 600 μM, respectively). Compared with iGluSnFR, iGlu u has a sixfold faster dissociation rate in vitro and fivefold faster kinetics in synapses. Fitting a three-state model to kinetic data, we identify the large conformational change after glutamate binding as the rate-limiting step. In rat hippocampal slice culture stimulated at 100 Hz, we find that iGlu u is sufficiently fast to resolve individual glutamate release events, revealing that glutamate is rapidly cleared from the synaptic cleft. Depression of iGlu u responses during 100-Hz trains correlates with depression of postsynaptic EPSPs, indicating that depression during high-frequency stimulation is purely presynaptic in origin. At individual boutons, the recovery from depression could be predicted from the amount of glutamate released on the second pulse (paired pulse facilitation/depression), demonstrating differential frequency-dependent filtering of spike trains at Schaffer collateral boutons.
AB - Glutamatergic synapses display a rich repertoire of plasticity mechanisms on many different time scales, involving dynamic changes in the efficacy of transmitter release as well as changes in the number and function of postsynaptic glutamate receptors. The genetically encoded glutamate sensor iGluSnFR enables visualization of glutamate release from presynaptic terminals at frequencies up to ∼10 Hz. However, to resolve glutamate dynamics during high-frequency bursts, faster indicators are required. Here, we report the development of fast (iGlu f ) and ultrafast (iGlu u ) variants with comparable brightness but increased Kd for glutamate (137 μM and 600 μM, respectively). Compared with iGluSnFR, iGlu u has a sixfold faster dissociation rate in vitro and fivefold faster kinetics in synapses. Fitting a three-state model to kinetic data, we identify the large conformational change after glutamate binding as the rate-limiting step. In rat hippocampal slice culture stimulated at 100 Hz, we find that iGlu u is sufficiently fast to resolve individual glutamate release events, revealing that glutamate is rapidly cleared from the synaptic cleft. Depression of iGlu u responses during 100-Hz trains correlates with depression of postsynaptic EPSPs, indicating that depression during high-frequency stimulation is purely presynaptic in origin. At individual boutons, the recovery from depression could be predicted from the amount of glutamate released on the second pulse (paired pulse facilitation/depression), demonstrating differential frequency-dependent filtering of spike trains at Schaffer collateral boutons.
KW - Animals
KW - Glutamic Acid
KW - Hippocampus
KW - Male
KW - Neuronal Plasticity
KW - Patch-Clamp Techniques
KW - Presynaptic Terminals
KW - Pyramidal Cells
KW - Rats
KW - Rats, Wistar
KW - Synapses
KW - Synaptic Transmission
KW - Journal Article
KW - Research Support, Non-U.S. Gov't
U2 - 10.1073/pnas.1720648115
DO - 10.1073/pnas.1720648115
M3 - SCORING: Journal article
C2 - 29735711
VL - 115
SP - 5594
EP - 5599
JO - P NATL ACAD SCI USA
JF - P NATL ACAD SCI USA
SN - 0027-8424
IS - 21
ER -