Identification of a human synaptotagmin-1 mutation that perturbs synaptic vesicle cycling

Baker, Kate, Gordon, Sarah L., Grozeva, Detelina ORCID: https://orcid.org/0000-0003-3239-8415, van Kogelenberg, Margriet, Roberts, Nicola Y., Pike, Michael, Blair, Edward, Hurles, Matthew E., Chong, W. Kling, Baldeweg, Torsten, Kurian, Manju A., Boyd, Stewart G., Cousin, Michael A. and Raymond, F. Lucy 2015. Identification of a human synaptotagmin-1 mutation that perturbs synaptic vesicle cycling. Journal of Clinical Investigation 125 (4) , pp. 1670-1678. 10.1172/JCI79765

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Abstract

Synaptotagmin-1 (SYT1) is a calcium-binding synaptic vesicle protein that is required for both exocytosis and endocytosis. Here, we describe a human condition associated with a rare variant in SYT1. The individual harboring this variant presented with an early onset dyskinetic movement disorder, severe motor delay, and profound cognitive impairment. Structural MRI was normal, but EEG showed extensive neurophysiological disturbances that included the unusual features of low-frequency oscillatory bursts and enhanced paired-pulse depression of visual evoked potentials. Trio analysis of whole-exome sequence identified a de novo SYT1 missense variant (I368T). Expression of rat SYT1 containing the equivalent human variant in WT mouse primary hippocampal cultures revealed that the mutant form of SYT1 correctly localizes to nerve terminals and is expressed at levels that are approximately equal to levels of endogenous WT protein. The presence of the mutant SYT1 slowed synaptic vesicle fusion kinetics, a finding that agrees with the previously demonstrated role for I368 in calcium-dependent membrane penetration. Expression of the I368T variant also altered the kinetics of synaptic vesicle endocytosis. Together, the clinical features, electrophysiological phenotype, and in vitro neuronal phenotype associated with this dominant negative SYT1 mutation highlight presynaptic mechanisms that mediate human motor control and cognitive development.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine Centre for Trials Research (CNTRR)
Publisher:	American Society for Clinical Investigation
ISSN:	0021-9738
Date of Acceptance:	8 January 2015
Last Modified:	09 Nov 2022 10:40
URI:	https://orca.cardiff.ac.uk/id/eprint/140285

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