Human post-mortem synapse proteome integrity screening for proteomic studies of postsynaptic complexes.

Àlex Bayés,Clare M Galtrey,Clémence Simonnet,Gemma Gou,Mark O Collins,Louie N Van De Lagemaat,Mike Dr Croning,David Milward,Colin Smith,Seth Gn Grant,Jyoti S Choudhary,Ian R Whittle,Marcia Roy

doi:10.1186/s13041-014-0088-4

Abstract

BackgroundSynapses are fundamental components of brain circuits and are disrupted in over 100 neurological and psychiatric diseases. The synapse proteome is physically organized into multiprotein complexes and polygenic mutations converge on postsynaptic complexes in schizophrenia, autism and intellectual disability. Directly characterising human synapses and their multiprotein complexes from post-mortem tissue is essential to understanding disease mechanisms. However, multiprotein complexes have not been directly isolated from human synapses and the feasibility of their isolation from post-mortem tissue is unknown.ResultsHere we establish a screening assay and criteria to identify post-mortem brain samples containing well-preserved synapse proteomes, revealing that neocortex samples are best preserved. We also develop a rapid method for the isolation of synapse proteomes from human brain, allowing large numbers of post-mortem samples to be processed in a short time frame. We perform the first purification and proteomic mass spectrometry analysis of MAGUK Associated Signalling Complexes (MASC) from neurosurgical and post-mortem tissue and find genetic evidence for their involvement in over seventy human brain diseases.ConclusionsWe have demonstrated that synaptic proteome integrity can be rapidly assessed from human post-mortem brain samples prior to its analysis with sophisticated proteomic methods. We have also shown that proteomics of synapse multiprotein complexes from well preserved post-mortem tissue is possible, obtaining structures highly similar to those isolated from biopsy tissue. Finally we have shown that MASC from human synapses are involved with over seventy brain disorders. These findings should have wide application in understanding the synaptic basis of psychiatric and other mental disorders.Electronic supplementary materialThe online version of this article (doi:10.1186/s13041-014-0088-4) contains supplementary material, which is available to authorized users.

Highlights

Synapses are fundamental components of brain circuits and are disrupted in over 100 neurological and psychiatric diseases
The prototype postsynaptic supercomplexes are known as MASC (MAGUK Associated Signalling Complexes) and they are organized around scaffolding proteins encoded by the DLG/Matrix associated guanilate Kinase (MAGUK) gene family
We have shown that the HUman Synaptic Proteome Integrity Ratio (HUSPIR), an indicator of postsynaptic proteome integrity, denotes that the synaptic proteome is better conserved in cortical than other brain regions

Summary

Introduction

Synapses are fundamental components of brain circuits and are disrupted in over 100 neurological and psychiatric diseases. Proteomic mass spectrometry analysis of mammalian synapses demonstrated that synapse proteomes are highly complex with over 1000 proteins in humans [2,3] This knowledge, combined with human genetic studies, enabled the systematic identification and classification of human. The importance of MASCs for cognition is emphasized by human genetic studies of mental disorders including schizophrenia, autism, intellectual disability and other diseases, which show mutations in MASC components [15,16,17,18]; mutations of MASC genes in mice result in cognitive impairments [4,19,20,21]

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