Reduction of mutant ATXN1 rescues premature death in a conditional SCA1 mouse model

• Main Authors: Ciaburri, N.A (Author), Nitschke, L. (Author), Orengo, J.P (Author), Orr, H.T (Author), van der Heijden, M.E (Author), Zoghbi, H.Y (Author)
• Format: Article
• Language: English
• Published: American Society for Clinical Investigation 2022
• Online Access: View Fulltext in Publisher

 Spinocerebellar ataxia type 1 (SCA1) is an adult-onset neurodegenerative disorder. As disease progresses, motor neurons are affected, and their dysfunction contributes toward the inability to maintain proper respiratory function, a major driving force for premature death in SCA1. To investigate the isolated role of motor neurons in SCA1, we created a conditional SCA1 (cSCA1) mouse model. This model suppresses expression of the pathogenic SCA1 allele with a floxed stop cassette. cSCA1 mice crossed to a ubiquitous Cre line recapitulate all the major features of the original SCA1 mouse model; however, they took twice as long to develop. We found that the cSCA1 mice produced less than half of the pathogenic protein compared with the unmodified SCA1 mice at 3 weeks of age. In contrast, restricted expression of the pathogenic SCA1 allele in motor neurons only led to a decreased distance traveled of mice in the open field assay and did not affect body weight or survival. We conclude that a 50% or greater reduction of the mutant protein has a dramatic effect on disease onset and progression; furthermore, we conclude that expression of polyglutamine-expanded ATXN1 at this level specifically in motor neurons is not sufficient to cause premature lethality. Copyright: © 2022, Orengo et al.