Schwann cells expressing dismutase active mutant SOD1 unexpectedly slow disease progression in ALS mice

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 106; no. 11; pp. 4465 - 4470
• Main Authors: Lobsiger, Christian S, Boillee, Severine, McAlonis-Downes, Melissa, Khan, Amir M, Feltri, M. Laura, Yamanaka, Koji, Cleveland, Don W
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 17.03.2009; National Acad Sciences
• Subjects: Amyotrophic lateral sclerosis; Amyotrophic Lateral Sclerosis - pathology; Amyotrophic Lateral Sclerosis - prevention & control; animal models; Animals; Astrocytes; Axons; Biological Sciences; Cells; disease course; Disease Models, Animal; Disease Progression; Down-Regulation; Gene expression; gene expression regulation; genes; Inactivation; insulin-like growth factor I; Insulin-Like Growth Factor I - biosynthesis; Mice; Motor neuron disease; Motor neurons; Mutants; Mutation; nerve tissue; Nervous system diseases; neurodegenerative diseases; Neuroglia; Neurons; Neurons - metabolism; Rodents; Schwann cells; Schwann Cells - metabolism; Sciatic nerve; Superoxide Dismutase - biosynthesis; Superoxide Dismutase - physiology; Superoxide Dismutase-1
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.0813339106

Neurodegeneration in an inherited form of ALS is non-cell-autonomous, with ALS-causing mutant SOD1 damage developed within multiple cell types. Selective inactivation within motor neurons of an ubiquitously expressed mutant SOD1 gene has demonstrated that mutant damage within motor neurons is a determinant of disease initiation, whereas mutant synthesis within neighboring astrocytes or microglia accelerates disease progression. We now report the surprising finding that diminished synthesis (by 70%) within Schwann cells of a fully dismutase active ALS-linked mutant (SOD1G³⁷R) significantly accelerates disease progression, accompanied by reduction of insulin-like growth factor 1 (IGF-1) in nerves. Coupled with shorter disease duration in mouse models caused by dismutase inactive versus dismutase active SOD1 mutants, our findings implicate an oxidative cascade during disease progression that is triggered within axon ensheathing Schwann cells and that can be ameliorated by elevated dismutase activity. Thus, therapeutic down-regulation of dismutase active mutant SOD1 in familial forms of ALS should be targeted away from Schwann cells.