Proteomic Characterization of a Mouse Model of Familial Danish Dementia

Monica Vitale,Giovanni Renzone,Nicola Zambrano,Andrea Scaloni,Shuji Matsuda,Luciano D'Adamio

doi:10.1155/2012/728178

Abstract

A dominant mutation in the ITM2B/BRI2 gene causes familial Danish dementia (FDD) in humans. To model FDD in animal systems, a knock-in approach was recently implemented in mice expressing a wild-type and mutant allele, which bears the FDD-associated mutation. Since these FDDKI mice show behavioural alterations and impaired synaptic function, we characterized their synaptosomal proteome via two-dimensional differential in-gel electrophoresis. After identification by nanoliquid chromatography coupled to electrospray-linear ion trap tandem mass spectrometry, the differentially expressed proteins were classified according to their gene ontology descriptions and their predicted functional interactions. The Dlg4/Psd95 scaffold protein and additional signalling proteins, including protein phosphatases, were revealed by STRING analysis as potential players in the altered synaptic function of FDDKI mice. Immunoblotting analysis finally demonstrated the actual downregulation of the synaptosomal scaffold protein Dlg4/Psd95 and of the dual-specificity phosphatase Dusp3 in the synaptosomes of FDDKI mice.

Highlights

Familial Danish Dementia (FDD) is a neurodegenerative disease characterized by early cataracts, deafness, progressive ataxia, and dementia
In order to characterize the synaptosomal proteome of the available mouse model of familial Danish dementia (FDD), we used the differential in-gel electrophoresis approach (2D-DIGE), which was applied to synaptosomal extracts from wild-type and FDDKI mice
Three biological replicates of synaptosomal preparations from wild-type and FDDKI mice were generated for protein extraction and fluorescence labelling with Cy-dyes

Summary

Introduction

Familial Danish Dementia (FDD) is a neurodegenerative disease characterized by early cataracts, deafness, progressive ataxia, and dementia. FDD is caused by a decamer duplication in the 3 region of the ITM2B/BRI2 gene This mutation produces a longer 34 amino acid C-terminal fragment that accumulates as amyloid [4, 5]. Age-dependent deposition of Danish amyloid peptide was observed in the brain of a second transgenic model, with associated angiopathy and microhemorrhage, neuritic dystrophy, and neuroinflammation [17]. The analysis of FDDKI mouse model, carrying a mutant and a wild-type ITM2B/BRI2 allele, has shown that the Danish mutation causes impaired synaptic plasticity and deficits in hippocampal memory, in the absence of cerebral deposits and lesions [19]. Our validated results showed decreased representation of the synaptosomal scaffold protein Psd95/Dlg and of the Dusp phosphatase in the FDDKI synaptosomes

Materials and Methods

Results and Discussion

Experiments

Conclusions