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Updated: Jun 21, 2026
A Simple Composite Phenotype Scoring System for Evaluating Mouse Models of Cerebellar Ataxia
Published on: May 21, 2010
Reversibility of symptoms in a conditional mouse model of spinocerebellar ataxia type 3
Jana Boy1, Thorsten Schmidt, Hartwig Wolburg
1Department of Medical Genetics, University of Tuebingen, Tuebingen, Germany.
Abstract:
Spinocerebellar ataxia type 3 (SCA3) is caused by the expansion of a CAG repeat tract that affects the MJD1 gene which encodes the ataxin-3 protein. In order to analyze whether symptoms caused by ataxin-3 with an expanded repeat are reversible in vivo, we generated a conditional mouse model of SCA3 using the Tet-Off system. We used a full-length human ataxin-3 cDNA with 77 repeats in order to generate the responder mouse line. After crossbreeding with a PrP promoter mouse line, double transgenic mice developed a progressive neurological phenotype characterized by neuronal dysfunction in the cerebellum, reduced anxiety, hyperactivity, impaired Rotarod performance and lower body weight gain. When ataxin-3 expression was turned off in symptomatic mice in an early disease state, the transgenic mice were indistinguishable from negative controls after 5 months of treatment. These results show that reducing the production of pathogenic ataxin-3 indeed may be a promising approach to treat SCA3, provided that such treatment is applied before irreversible damage has taken place and that it is continued for a sufficiently long time.
Insights
Symptoms of spinocerebellar ataxia type 3 (SCA3) may be reversible. Reducing pathogenic ataxin-3 production in mice reversed neurological symptoms, suggesting a potential treatment approach for SCA3.
Area of Science:
- Neuroscience
- Genetics
- Molecular Biology
Background:
- Spinocerebellar ataxia type 3 (SCA3) is a neurodegenerative disorder caused by expanded CAG repeats in the MJD1 gene, leading to dysfunctional ataxin-3 protein.
- The reversibility of SCA3 symptoms in vivo remains an important question for therapeutic development.
Purpose of the Study:
- To investigate whether the neurological symptoms of spinocerebellar ataxia type 3 (SCA3) are reversible in a conditional mouse model.
- To assess the potential of reducing pathogenic ataxin-3 production as a therapeutic strategy for SCA3.
Main Methods:
- Generation of a conditional SCA3 mouse model using the Tet-Off system with human ataxin-3 cDNA (77 repeats).
- Crossbreeding with a PrP promoter mouse line to create double transgenic mice exhibiting SCA3 phenotypes.
- Monitoring neurological symptoms and assessing reversibility by turning off ataxin-3 expression in symptomatic mice.
Main Results:
- Conditional SCA3 mice developed progressive neurological deficits, including cerebellar dysfunction, hyperactivity, and impaired motor performance.
- Upon withdrawal of the inducer, silencing ataxin-3 expression in early symptomatic mice led to a complete reversal of neurological phenotypes within 5 months.
- Treated mice became indistinguishable from control littermates, indicating symptom reversibility.
Conclusions:
- Reducing the production of pathogenic ataxin-3 is a promising therapeutic strategy for spinocerebellar ataxia type 3.
- Early intervention and sustained treatment are crucial for reversing SCA3 symptoms before irreversible neuronal damage occurs.
