Published: January 19, 2011 r2011 American Chemical Society 1538 dx.doi.org/10.1021/pr1009096 | J. Proteome Res. 2011, 10, 1538–1547 ARTICLE pubs.acs.org/jpr Protein Array Based Interactome Analysis of Amyloid-β Indicates an Inhibition of Protein Translation Dezso P. Virok,* ,†,# D ora Simon, ‡,# Zsolt Bozs o, ‡ R obert Rajk o, § Zsolt Datki, †  Eva B  alint, † Viktor Szegedi, † Tam as Jan  aky, ‡ Botond Penke, †,‡ and Lívia F€ ul€ op ‡ † Institute for Plant Genomics, Human Biotechnology, Bioenergy (Bay-Gen) and Szeged, Hungary ‡ Department of Medical Chemistry, University of Szeged, Szeged, Hungary § Faculty of Engineering, University of Szeged, Szeged, Hungary b S Supporting Information ’ INTRODUCTION Alzheimer’s disease (AD) is the most common form of dementia in the developed world and has a severe socioecono- mical impact on society. The histological hallmarks of the diseases are the accumulation of amyloid-β (Aβ) fibrils in the extracellular space, the appearance of hyperphosphorylated-tau protein aggregates intracellularly and the progressive loss of neurons. Fibrillar Aβ was suspected of being the primary agent that causes the AD-related histopathology and eventually clinical symptoms. However, the accumulation of the predominantly fibrillar Aβ containing plaques does not correlate well with the clinical symptoms, 1-3 and plaque accumulation appears later than the observed histopathology in animal models. 4,5 Also anti- Aβ immunization leads to the reversal of memory loss without decreasing the plaque concentration. 6,7 Recently, the oligomeric form of Aβ has become the focus of attention, and is regarded as an important specimen that mediates cyto- and synaptotoxicity. The findings supporting the role of oligomeric Aβ in the pathogenesis of AD are numerous and include diverse cellular and supracellular processes. Oligomeric Aβ was shown to perturb potentially AD-related signal transduction cascades in- cluding the induction of the ERK/MAPK signaling, 8 increasing calcineurin activity and calcineurin-dependent CREB and BAD dephosphorylation and cell death, 9 inducing tau hyperphosphorylation 10 and inhibiting the phosphatidylino- sitol-4,5-bisphosphate metabolism. 11 Oligomeric Aβ has an impact on the proteome and phosphoproteome of the choli- nergic SN56 cells 12 and transcriptional activity of human neuroblastoma cells. 12 Oligomeric Aβ has also been shown to inhibit axonal transport and the synaptic vesicle rapid endocytosis pathway, 13 and it decreased cellular viability both in vitro and In Vivo 14,15 in some cases more effectively than fibrillar Aβ. 15,16 Despite its important role in AD pathogen- esis, the binding partners by which the oligomeric Aβ med- iates its toxicity have not been investigated at a proteome or subproteome level. The protein array technology is a novel postgenomic method to investigate protein-protein interac- tions in a high-throughput manner. The technology has been successfully used for the identification of protein interaction partners, 17,18 identification of kinase substrates and inhibitors 19,20 and autoantibody profiling. 21-23 To investigate the potential interaction partners of oligomeric Aβ, we used protein arrays with 8163 human proteins covering a significant portion of the Received: September 6, 2010 ABSTRACT: Oligomeric amyloid-β is currently of interest in amyloid-β mediated toxicity and the pathogenesis of Alzheimer’s disease. Mapping the amyloid-β interaction partners could help to discover novel pathways in disease pathogenesis. To discover the amyloid-β interaction partners, we applied a protein array with more than 8100 unique recombinantly expressed human proteins. We identified 324 proteins as potential interactors of oligomeric amyloid-β. The Gene Ontology functional analysis of these proteins showed that oligomeric amyloid-β bound to multiple proteins with diverse functions both from extra and intracellular localizations. This undiscriminating binding phenotype indicates that multiple protein interactions mediate the toxicity of the oligomeric amyloid-β. The most highly impacted cellular system was the protein translation machinery. Oligomeric amyloid-β could bind to altogether 24 proteins involved in translation initiation and elongation. The binding of amyloid-β to purified rat hippocampal ribosomes validated the protein array results. More importantly, in vitro translation assays showed that the oligomeric amyloid-β had a concentration dependent inhibitory activity on translation. Our results indicate that the inhibited protein synthesis is one of the pathways that can be involved in the amyloid-beta induced neurotoxicity. KEYWORDS: Alzheimer’s, oligomeric, amyloid-β, protein array, protein chip, proteomics, interactome