α-SAP97 and β-SAP97 scaffold AMPA receptors at the glutamatergic synapse

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dc.contributor.author Goodman, Lucy en
dc.contributor.author Baddeley, David en
dc.contributor.author Soeller, C en
dc.contributor.author Montgomery, Johanna en
dc.coverage.spatial Cairns, Australia en
dc.date.accessioned 2018-10-14T21:02:16Z en
dc.date.issued 2015-08-22 en
dc.identifier.uri http://hdl.handle.net/2292/41292 en
dc.description.abstract Aim: The location and density of synaptic AMPA receptors is controlled by scaffolding proteins that lie directly beneath the postsynaptic membrane. Two N-terminal isoforms of SAP97, αSAP97 and βSAP97, are thought to play opposite and complimentary roles in regulating surface AMPA receptor location. Electrophysiology evidence suggests that αSAP97 increases synaptic strength by clustering AMPA receptors at synapses, whereas βSAP97 decreases synaptic strength by scaffolding these receptors at perisynaptic locations. However, this hypothesis has not yet been verified with imaging, as the neuronal synapse lies below the resolution limit of conventional optical microscopy. Methods: Cultured rat hippocampal neurons were transiently transfected with αor βSAP97-eGFP, short-hairpin RNA to knock-down βSAP97 expression, or an empty eGFP control plasmid. A single molecule localisation method of super resolution imaging known as dSTORM was used to image the distribution of surface AMPA receptors on transfected neurons. Confocal microscopy was used to quantify both the size of these neurons, and the morphology and density of their synapses. Results: Both α and βSAP97 overexpression enhanced the clustering of GluA1-containing AMPA receptors at synapses compared to eGFP controls, whereas acute knock-down of βSAP97 relocated the receptors to perisynaptic sites (p < 0.001). In addition, overexpression of βSAP97 increased the density of GluA1 subunits at synapses (p < 0.001), and reduced the proportion of mature, mushroom-shaped dendritic spines (p = 0.029). Both α and βSAP97 overexpression increased the size of the presynaptic active zone via transsynaptic signalling (p < 0.001/p = 0.024). Compared to αSAP97, βSAP97 overexpression reduced the size of the dendritic tree (p = 0.027), and the proportion of postsynaptic densities with direct access to the presynaptic active zone (p = 0.003). Conclusions: The previously observed differences in synaptic strength between α and βSAP97 expressing neurons can be explained by differences in the number of synapses, rather than the location of surface AMPA receptors on the postsynaptic membrane. Both α and βSAP97 can scaffold AMPA receptors at synapses, whereas βSAP97 can actively promote synaptic incorporation of AMPA receptors by releasing them from the perisynaptic pool. en
dc.relation.ispartof From synapses to circuits and behaviour en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.title α-SAP97 and β-SAP97 scaffold AMPA receptors at the glutamatergic synapse en
dc.type Conference Poster en
dc.rights.holder Copyright: The authors en
pubs.author-url https://www.neurochemistry.org/biennial-meeting/satellite-meetings.html?id=233 en
dc.rights.accessrights http://purl.org/eprint/accessRights/OpenAccess en
pubs.elements-id 728317 en
pubs.org-id Bioengineering Institute en
pubs.org-id Medical and Health Sciences en
pubs.org-id Medical Sciences en
pubs.org-id Physiology Division en
pubs.org-id Optometry and Vision Science en
pubs.org-id Science en
pubs.org-id Science Research en
pubs.org-id Maurice Wilkins Centre (2010-2014) en
pubs.record-created-at-source-date 2018-03-04 en


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