PSD95 nanoclusters are postsynaptic building blocks in hippocampus circuits.
The molecular features of synapses in the hippocampus underpin current models of learning and cognition. Although synapse ultra-structural diversity has been described in the canonical hippocampal circuitry, our knowledge of sub-synaptic organisation of synaptic molecules remains largely unknown. To address this, mice were engineered to express Post Synaptic Density 95 protein (PSD95) fused to either eGFP or mEos2 and imaged with two orthogonal super-resolution methods: gated stimulated emission depletion (g-STED) microscopy and photoactivated localisation microscopy (PALM). Large-scale analysis of ~100,000 synapses in 7 hippocampal sub-regions revealed they comprised discrete PSD95 nanoclusters that were spatially organised into single and multi-nanocluster PSDs. Synapses in different sub-regions, cell-types and locations along the dendritic tree of CA1 pyramidal neurons, showed diversity characterised by the number of nanoclusters per synapse. Multi-nanocluster synapses were frequently found in the CA3 and dentate gyrus sub-regions, corresponding to large thorny excrescence synapses. Although the structure of individual nanoclusters remained relatively conserved across all sub-regions, PSD95 packing into nanoclusters also varied between sub-regions determined from nanocluster fluorescence intensity. These data identify PSD95 nanoclusters as a basic structural unit, or building block, of excitatory synapses and their number characterizes synapse size and structural diversity.
Centre for Clinical Brain Sciences (CCBS), University of Edinburgh, Edinburgh, United Kingdom.|Edinburgh Super-Resolution Imaging Consortium (ESRIC), Heriot Watt University, Edinburgh, United Kingdom.
Matthew J
MJ
Broadhead
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW. United Kingdom.
Mathew H
MH
Horrocks
Centre for Clinical Brain Sciences (CCBS), University of Edinburgh, Edinburgh, United Kingdom.
Fei
F
Zhu
Cambridge Advanced Imaging Centre (CAIC), University of Cambridge, Cambridge, United Kingdom.
Leila
L
Muresan
Instituto Cajal (CSIC) and Centro de Tecnología Biomédica (UPM), Madrid, Spain.
Ruth
R
Benavides-Piccione
Instituto Cajal (CSIC) and Centro de Tecnología Biomédica (UPM), Madrid, Spain.
Javier
J
DeFelipe
Synome Ltd, Babraham Research Campus, Cambridge, United Kingdom.
David
D
Fricker
Synome Ltd, Babraham Research Campus, Cambridge, United Kingdom.
Maksym V
MV
Kopanitsa
Edinburgh Super-Resolution Imaging Consortium (ESRIC), Heriot Watt University, Edinburgh, United Kingdom.|Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
Rory R
RR
Duncan
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW. United Kingdom.
David
D
Klenerman
Centre for Clinical Brain Sciences (CCBS), University of Edinburgh, Edinburgh, United Kingdom.
Noboru H
NH
Komiyama
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW. United Kingdom.
Steven F
SF
Lee
Centre for Clinical Brain Sciences (CCBS), University of Edinburgh, Edinburgh, United Kingdom.
Seth G N
SG
Grant
D000818:Animals; D000076122:Disks Large Homolog 4 Protein / Q000737:chemistry / Q000378:metabolism*; D054351:Electrical Synapses / Q000378:metabolism*; D006624:Hippocampus / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008853:Microscopy; D049329:Nanostructures / Q000737:chemistry; D055503:Protein Multimerization; D017966:Pyramidal Cells / Q000502:physiology*; D009435:Synaptic Transmission
C501444:DLG4 protein, human; D000076122:Disks Large Homolog 4 Protein