SNAP25 disease mutations change the energy landscape for synaptic exocytosis due to aberrant SNARE interactions

SNAP25 is one of three neuronal SNAREs driving synaptic vesicle exocytosis. We studied three mutations in SNAP25 that cause epileptic encephalopathy: V48F, and D166Y in the synaptotagmin-1 (Syt1)-binding interface, and I67N, which destabilizes the SNARE complex. All three mutations reduced Syt1-depe...

Full description

Saved in:

Bibliographic Details
Published in:	eLife Vol. 12
Main Authors:	Kádková, Anna, Murach, Jacqeline, Østergaard, Maiken, Malsam, Andrea, Malsam, Jörg, Lolicato, Fabio, Nickel, Walter, Söllner, Thomas H, Sørensen, Jakob Balslev
Format:	Journal Article
Language:	English
Published:	England eLife Sciences Publications Ltd 27-02-2024 eLife Sciences Publications, Ltd
Subjects:	Animals Cell Biology Convulsions & seizures Encephalopathy Energy Epilepsy Excitatory postsynaptic potentials Exocytosis Genotype & phenotype Hippocampus Intellectual disabilities Magnetic resonance imaging Membrane Fusion Mice Mutants Mutation Neuroscience Proteins SNAP receptors SNAP-25 protein SNARE SNARE Proteins - genetics SNAREopathy Synaptic Transmission Synaptotagmin mouse cell biology neuroscience SNAREopathy exocytosis synaptic transmission synaptotagmin encephalopathy hippocampal neurons SNARE
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	SNAP25 is one of three neuronal SNAREs driving synaptic vesicle exocytosis. We studied three mutations in SNAP25 that cause epileptic encephalopathy: V48F, and D166Y in the synaptotagmin-1 (Syt1)-binding interface, and I67N, which destabilizes the SNARE complex. All three mutations reduced Syt1-dependent vesicle docking to SNARE-carrying liposomes and Ca -stimulated membrane fusion in vitro and when expressed in mouse hippocampal neurons. The V48F and D166Y mutants (with potency D166Y > V48F) led to reduced readily releasable pool (RRP) size, due to increased spontaneous (miniature Excitatory Postsynaptic Current, mEPSC) release and decreased priming rates. These mutations lowered the energy barrier for fusion and increased the release probability, which are gain-of-function features not found in knockout (KO) neurons; normalized mEPSC release rates were higher (potency D166Y > V48F) than in the KO. These mutations (potency D166Y > V48F) increased spontaneous association to partner SNAREs, resulting in unregulated membrane fusion. In contrast, the I67N mutant decreased mEPSC frequency and evoked EPSC amplitudes due to an increase in the height of the energy barrier for fusion, whereas the RRP size was unaffected. This could be partly compensated by positive charges lowering the energy barrier. Overall, pathogenic mutations in SNAP25 cause complex changes in the energy landscape for priming and fusion.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 These authors contributed equally to this work.
ISSN:	2050-084X 2050-084X
DOI:	10.7554/eLife.88619