Differential Activation of the ER Stress Factor XBP1 by Oligomeric Assemblies

Department of Neurology, University of Texas Medical Branch, Galveston, TX 77555, USA.
Neurochemical Research (Impact Factor: 2.59). 04/2012; 37(8):1707-17. DOI: 10.1007/s11064-012-0780-7
Source: PubMed


Several neurodegenerative disorders are characterized by protein misfolding, a phenomenon that results in perturbation of cellular homeostasis. We recently identified the protective activity of the ER stress response factor XBP1 (X-box binding protein 1) against Amyloid-ß1-42 (Aß42) neurotoxicity in cellular and Drosophila models of Alzheimer's disease. Additionally, subtoxic concentrations of Aß42 soluble aggregates (oligomers) induced accumulation of spliced (active) XBP1 transcripts, supporting the involvement of the ER stress response in Aß42 neurotoxicity. Here, we tested the ability of three additional disease-related amyloidogenic proteins to induce ER stress by analyzing XBP1 activation at the RNA level. Treatment of human SY5Y neuroblastoma cells with homogeneous preparations of α-Synuclein (α-Syn), Prion protein (PrP106-126), and British dementia amyloid peptide (ABri1-34) confirmed the high toxicity of oligomers compared to monomers and fibers. Additionally, α-Syn oligomers, but not monomers or fibers, demonstrated potent induction of XBP1 splicing. On the other hand, PrP106-126 and ABri1-34 did not activate XBP1. These results illustrate the biological complexity of these structurally related assemblies and argue that oligomer toxicity depends on the activation of amyloid-specific cellular responses.

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    • "Moreover, selective invalidation of XBP-1 in dopaminergic neurons of the substantia nigra pars compacta triggers chronic ER stress and neurodegeneration of the neurons targeted [39]. It has also been postulated that α-synuclein aggregates promote XBP-1 splicing and activation in human neuroblastoma [41]. "
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