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Decreased Levels of VAMP2 and Monomeric Alpha-Synuclein Correlate with Duration of Dementia

Lookup NU author(s): Mary Johnson, Professor Johannes Attems, Professor John O'Brien, Professor Alan ThomasORCiD

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Abstract

Alpha-synuclein (alpha-syn) aggregations are the key pathological hallmark of dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), but are also frequently present in Alzheimer's disease (AD). Much remains unknown about the role of alpha-syn in the synapse and the wider role of synaptic dysfunction in these dementias. Changes in concentrations of key 'SNAP (Soluble N-ethylmaleimide Sensitive Factor Attachment Protein) Receptor' (SNARE) proteins as a consequence of alterations in the aggregation state of alpha-syn may contribute to synaptic dysfunction in patients with DLB, PDD, and AD and result in impaired cognition. We have studied a large cohort (n = 130) of autopsy confirmed DLB, PDD, AD, and control brains. Using semi-quantitative western blotting, we have demonstrated significant changes across the diagnostic groups of DLB, PDD, and AD in the SNARE and vesicle proteins syntaxin, Munc18, VAMP2, and monomeric alpha-syn in the prefrontal cortex, with a significant reduction of Munc18 in AD patients (p < 0.001). This correlated to the final MMSE score before death (p = 0.016). We also identified a significant negative correlation between the duration of dementia and the levels of the binding partners VAMP2 (p = 0.0004) and monomeric alpha-syn (p = 0.0002). Our findings may indicate that an upregulation of SNARE complex related proteins occurs in the early stages of disease as an attempt at compensating for failing synapses, prior to widespread deposition of pathological alpha-syn.

Publication metadata

Author(s): Vallortigara J, Whitfield D, Quelch W, Alghamdi A, Howlett D, Hortobágyi T, Johnson M, Attems J, O'Brien JT, Thomas A, Ballard CG, Aarsland D, Francis PT

Publication type: Article

Publication status: Published

Journal: Journal of Alzheimer's Disease

Year: 2016

Volume: 50

Issue: 1

Pages: 101-110

Print publication date: 01/01/2016

Online publication date: 30/11/2015

Acceptance date: 08/10/2015

ISSN (print): 1387-2877

ISSN (electronic): 1875-8908

Publisher: IOS PRESS

URL: http://dx.doi.org/10.3233/JAD-150707

DOI: 10.3233/JAD-150707

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