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Oligodendrocyte subtype imbalance and dysfunction contribute to motor deficits and Purkinje cell axonopathy in SCA1

ABSTRACT: Spinocerebellar ataxia type 1 (SCA1) is a neurodegenerative disease marked by progressive motor deficits and Purkinje cell (PC) degeneration, driven by polyglutamine expansion in ataxin-1. While oligodendroglial dysfunction precedes PC loss, its direct contribution toward SCA1 pathogenesis remains unclear. Here, using an oligodendroglia-specific SCA1 conditional knock-in mouse model, we demonstrate that mutant ataxin-1 in oligodendrocytes is sufficient to drive aspects of SCA1-related pathology, including dysregulated myelination, PC axonal shrinkage, and torpedo formation, ultimately impairing motor coordination. Cross-species single-nucleus RNA-sequencing reveals cerebellar oligodendrocyte subtypes with distinct gene expression and abundance dysregulation that contribute to demyelination. This, compounded by a progressive decline in the neuroprotective functions of a cerebellar-specific oligodendrocyte subtype, establishes a critical link between demyelination, axo-myelinic dysfunction, and axonal pathology in SCA1. Upstream transcriptional regulator analysis in oligodendroglia identifies TCF7L2 and HTT as key mediators of oligodendroglial dysfunction in SCA1, suggesting shared pathogenic mechanisms with other polyglutamine diseases. These findings position oligodendroglia as central players in SCA1 pathogenesis and underscore their essential role in supporting PC of axonal integrity.

ORGANISM(S): Mus musculus

PROVIDER: GSE319510 | GEO | 2026/03/26

REPOSITORIES: GEO

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Project description:A number of human neurodegenerative diseases result from the expansion of a glutamine repeat within the disease-causing protein. Spinocerebellar ataxia type1 is one such disease, caused by expansion of a polyglutamine tract in the novel protein ataxin-1. To faithfully model SCA1 in the mouse, we generated knock-in mice carrying 154 CAG repeats in the mouse Sca1 locus. These mice reproduced many aspects of the human disease. Despite ubiquitous expression of the mutant protein, they developed slowly progressive selective neurodegeneration , which is most distinct in Purkinje cells and spinal cord. Alterations in gene expression have been proposed to be involved in the pathogenesis of polyglutamine disease including SCA1, but the changes of gene expression in an authentic disease model have not been characterized. We believe that knowledge of these genes will give insight into the pathophysiology of SCA1 and may ultimately be relevant to the treatment of SCA1.,We will determine gene expression patterns in the cerebellum and forebrain at three different time points.,We propose that the genes whose expression is affected by mutant ataxin-1 expression are effectors for neuronal dysfunction and neuronal degeneration in the knock-in mice. We also hypothesize the difference in the expression levels of these genes accounts for selective vulnerability of neurons.,We will examine three time points: 4 weeks, 11 weeks, and 20 weeks of age. We have shown that the mice developed motor incoordination as revealed by rotating rod test as early as 5 weeks of age but it was not until 10 weeks that they start showing clear neurological phenotype such as clasping. At each point, we will compare the pattern between the mutant and wild-type littermate. Animals will be prepared and sacrificed by a standard procedure. Cerebellum and spinal cord are the most affected areas whereas forebrain shows less neurodegeneration. Tissue will be rapidly dissected from cerebellum and forebrain, frozen in liquid nitrogen, and stored at ?80 C until analysis. Tissues will be sent to the centers (as opposed to RNA). We will be providing 9 tissue samples from three litters for each time point to mitigate any expression differences resulting from subtle differences of procedure or environment where the mice grow.

Project description:A number of human neurodegenerative diseases result from the expansion of a glutamine repeat within the disease-causing protein. Spinocerebellar ataxia type1 is one such disease, caused by expansion of a polyglutamine tract in the novel protein ataxin-1. To faithfully model SCA1 in the mouse, we generated knock-in mice carrying 154 CAG repeats in the mouse Sca1 locus. These mice reproduced many aspects of the human disease. Despite ubiquitous expression of the mutant protein, they developed slowly progressive selective neurodegeneration , which is most distinct in Purkinje cells and spinal cord. Alterations in gene expression have been proposed to be involved in the pathogenesis of polyglutamine disease including SCA1, but the changes of gene expression in an authentic disease model have not been characterized. We believe that knowledge of these genes will give insight into the pathophysiology of SCA1 and may ultimately be relevant to the treatment of SCA1. We will determine gene expression patterns in the cerebellum and forebrain at three different time points. We propose that the genes whose expression is affected by mutant ataxin-1 expression are effectors for neuronal dysfunction and neuronal degeneration in the knock-in mice. We also hypothesize the difference in the expression levels of these genes accounts for selective vulnerability of neurons. We will examine three time points: 4 weeks, 11 weeks, and 20 weeks of age. We have shown that the mice developed motor incoordination as revealed by rotating rod test as early as 5 weeks of age but it was not until 10 weeks that they start showing clear neurological phenotype such as clasping. At each point, we will compare the pattern between the mutant and wild-type littermate. Animals will be prepared and sacrificed by a standard procedure. Cerebellum and spinal cord are the most affected areas whereas forebrain shows less neurodegeneration. Tissue will be rapidly dissected from cerebellum and forebrain, frozen in liquid nitrogen, and stored at ?80 C until analysis. Tissues will be sent to the centers (as opposed to RNA). We will be providing 9 tissue samples from three litters for each time point to mitigate any expression differences resulting from subtle differences of procedure or environment where the mice grow. Keywords: time-course

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Oligodendrocyte subtype imbalance and dysfunction contribute to motor deficits and Purkinje cell axonopathy in SCA1

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