Cellular toxicity of mutant SOD1 protein is linked to an easily soluble, non-aggregated form in vitro

• Type of Material: Article
• Authors: Terrell E. Brotherton, Emory University; Yingjie Li, Emory University; Jonathan D Glass, Emory University
• Language: English
• Date: 2012-08-25
• Publisher: Elsevier: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2012 Elsevier Inc. All rights reserved
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.nbd.2012.08.010
• Title of Journal or Parent Work: Neurobiology of Disease
• ISSN: 0969-9961
• Volume: 49
• Start Page: 49
• End Page: 56
• Grant/Funding Information: This work was supported by Emory Neuroscience NINDS Core Facilities (P30 NS055077), and the Packard Center for ALS Research.
• Keywords: solubility; SOD1; aggregation; misfold; amyotrophic lateral sclerosis
• Research Categories: Biology, Neuroscience

Abstract

Mutations in superoxide dismutase 1 (SOD1) are found in approximately 20% of patients with familial amyotrophic lateral sclerosis. The propensity of mutant SOD1 to form aggregates in pathologically affected cells (i.e. motor neurons) has implicated these poorly soluble protein aggregates and/or their misfolded soluble precursors as being instrumental to the disease process. We investigated the relative solubility and toxicity of four different mutant SOD1 proteins in a cell-based model system and demonstrate that the mutant, misfolded SOD1 proteins that are the most soluble are also the most toxic. This toxicity was ameliorated by upregulating heat-shock protein chaperones in order to refold the soluble, misfolded protein, regardless of the presence of poorly soluble SOD1. We further demonstrate that increasing the solubility of a SOD1 mutant protein that is both poorly soluble and non-toxic, as compared to other mutant proteins, resulted in remarkably increased toxicity of the mutant SOD1. Again, this increased toxicity was attenuated by upregulating heat-shock protein chaperones in order to refold the soluble, misfolded proteins. These findings implicate easily soluble, misfolded SOD1 as being toxic to the cell and support the hypothesis that reducing solubility of mutant SOD1 proteins through aggregation may occur as a self-protective response in the cell.