TDP-43 or FUS-induced misfolded human wild-type SOD1 can propagate intercellularly in a prion-like fashion

• Published in: Scientific reports Vol. 6; no. 1; p. 22155
• Main Authors: Pokrishevsky, Edward, Grad, Leslie I., Cashman, Neil R.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.03.2016; Nature Publishing Group
• Subjects: 13/106; 14/63; 631/80/304; 631/92/609; 692/617/375/1917/1285; 82; 82/80; Amyotrophic lateral sclerosis; Amyotrophic Lateral Sclerosis - genetics; Amyotrophic Lateral Sclerosis - metabolism; Amyotrophic Lateral Sclerosis - pathology; Animals; Antibodies; Antibody Specificity; Culture Media, Conditioned; Cytotoxicity; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; FUS gene; FUS protein; Gene Knockdown Techniques; HEK293 Cells; Humanities and Social Sciences; Humans; Immunocytochemistry; Immunoprecipitation; Media; Mice; Mice, Transgenic; Motor neurons; Motor Neurons - metabolism; Motor Neurons - pathology; Motor task performance; multidisciplinary; Mutant Proteins - genetics; Mutant Proteins - metabolism; Mutation; Pathology; Prions - genetics; Prions - immunology; Prions - metabolism; Protein Folding; RNA, Small Interfering - genetics; RNA-Binding Protein FUS - genetics; RNA-Binding Protein FUS - metabolism; Science; siRNA; Superoxide dismutase; Superoxide Dismutase-1 - chemistry; Superoxide Dismutase-1 - genetics; Superoxide Dismutase-1 - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep22155

Amyotrophic lateral sclerosis (ALS), which appears to spread through the neuroaxis in a spatiotemporally restricted manner, is linked to heritable mutations in genes encoding SOD1, TDP-43, FUS, C9ORF72, or can occur sporadically without recognized genetic mutations. Misfolded human wild-type (HuWt) SOD1 has been detected in both familial and sporadic ALS patients, despite mutations in SOD1 accounting for only 2% of total cases. We previously showed that accumulation of pathological TDP-43 or FUS coexist with misfolded HuWtSOD1 in patient motor neurons and can trigger its misfolding in cultured cells. Here, we used immunocytochemistry and immunoprecipitation to demonstrate that TDP-43 or FUS-induced misfolded HuWtSOD1 can propagate from cell-to-cell via conditioned media and seed cytotoxic misfolding of endogenous HuWtSOD1 in the recipient cells in a prion-like fashion. Knockdown of SOD1 using siRNA in recipient cells, or incubation of conditioned media with misfolded SOD1-specific antibodies, inhibits intercellular transmission, indicating that HuWtSOD1 is an obligate seed and substrate of propagated misfolding. In this system, intercellular spread of SOD1 misfolding is not accompanied by transmission of TDP-43 or FUS pathology. Our findings argue that pathological TDP-43 and FUS may exert motor neuron pathology in ALS through the initiation of propagated misfolding of SOD1.