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Decreasing Mutant ATXN1 Nuclear Localization Improves a Spectrum of SCA1-Like Phenotypes and Brain Region Transcriptomic Profiles

ABSTRACT: Spinocerebellar ataxia type 1 (SCA1) is a dominant trinucleotide repeat neurodegenerative disease characterized by motor dysfunction, cognitive impairment, and premature death. Degeneration of cerebellar Purkinje cells is a frequent and prominent pathological feature of SCA1. We previously showed that transport of ATXN1 to Purkinje cell nuclei is required for pathology, where mutant ATXN1 alters transcription. To examine the role of ATXN1 nuclear localization broadly in SCA1-like disease pathogenesis, CRISPR-Cas9 was used to develop a mouse with an amino acid alteration (K772T) in the nuclear localization sequence of the expanded ATXN1 protein. Characterization of these mice indicates proper nuclear localization of mutant ATXN1 contributes to many disease-like phenotypes including motor dysfunction, cognitive deficits, and premature lethality. RNA sequencing analysis of genes with expression corrected to WT levels in Atxn1175QK772T/2Q mice indicates that transcriptomic aspects of SCA1 pathogenesis differ between the cerebellum, brainstem, cerebral cortex, hippocampus, and striatum.

ORGANISM(S): Mus musculus

PROVIDER: GSE218303 | GEO | 2022/12/01

REPOSITORIES: GEO

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Project description:Comparative analysis of cerebellar gene expression changes occurring in Sca1154Q/2Q and Sca7266Q/5Q knock-in mice; Polyglutamine diseases are inherited neurodegenerative disorders caused by expansion of CAG repeats encoding a glutamine tract in the disease-causing proteins. There are nine disorders each having distinct features but also clinical and pathological similarities. In particular, spinocerebellar ataxia type 1 and type 7 (SCA1 and SCA7) patients manifest cerebellar ataxia with degeneration of Purkinje cells. To determine whether the disorders share molecular pathogenic events, we studied two mouse models of SCA1 and SCA7 that express the glutamine-expanded protein from the respective endogenous loci. We found common transcriptional changes, with down-regulation of Insulin-like growth factor binding protein 5 (Igfbp5) representing one of the most robust changes. Igfbp5 down-regulation occurred in granule neurons through a non-cell autonomous mechanism and was concomitant with activation of of the Insulin-like growth factor (IGF) pathway and the type I IGF receptor on Purkinje cells. These data define one common pathogenic response in SCA1 and SCA7 and reveal the importance of intercellular mechanisms in their pathogenesis. Given that SCA1 and SCA7 share a cerebellar degenerative phenotype, we proposed that some shared molecular changes might occur in both diseases, and that common molecular alterations could pinpoint pathways that could be targeted to modulate or monitor the pathogenesis of more than one disease. We focused on transcriptional changes because both ATXN1 and ATXN7 play roles in transcriptional regulation and transcriptional defects can be detected in early-symptomatic stages of both SCA1 and SCA7 mouse models. To test our hypothesis, we examined cerebellar gene expression patterns in SCA1 and SCA7 knock-in (KI) models--Sca1154Q/2Q and Sca7266Q/5Q mice. Experiment Overall Design: Total cerebellar RNA samples were collected from Sca1154Q/2Q knock-in and wild type mice at the early symptomatic disease stage (4 weeks, n=3 knock-in and 3 wild type; 9-12 weeks, n=3 knock-in and 3 wild type). In parallel experiments, total cerebellar RNA samples were collected from Sca7266Q/5Q knock-in and wild type mice also at the early symptomatic disease stage (5 weeks, n=5 knock-in and 5 wild type).

Project description:Comparative analysis of cerebellar gene expression changes occurring in Sca1154Q/2Q and Sca7266Q/5Q knock-in mice Polyglutamine diseases are inherited neurodegenerative disorders caused by expansion of CAG repeats encoding a glutamine tract in the disease-causing proteins. There are nine disorders each having distinct features but also clinical and pathological similarities. In particular, spinocerebellar ataxia type 1 and type 7 (SCA1 and SCA7) patients manifest cerebellar ataxia with degeneration of Purkinje cells. To determine whether the disorders share molecular pathogenic events, we studied two mouse models of SCA1 and SCA7 that express the glutamine-expanded protein from the respective endogenous loci. We found common transcriptional changes, with down-regulation of Insulin-like growth factor binding protein 5 (Igfbp5) representing one of the most robust changes. Igfbp5 down-regulation occurred in granule neurons through a non-cell autonomous mechanism and was concomitant with activation of of the Insulin-like growth factor (IGF) pathway and the type I IGF receptor on Purkinje cells. These data define one common pathogenic response in SCA1 and SCA7 and reveal the importance of intercellular mechanisms in their pathogenesis. Given that SCA1 and SCA7 share a cerebellar degenerative phenotype, we proposed that some shared molecular changes might occur in both diseases, and that common molecular alterations could pinpoint pathways that could be targeted to modulate or monitor the pathogenesis of more than one disease. We focused on transcriptional changes because both ATXN1 and ATXN7 play roles in transcriptional regulation and transcriptional defects can be detected in early-symptomatic stages of both SCA1 and SCA7 mouse models. To test our hypothesis, we examined cerebellar gene expression patterns in SCA1 and SCA7 knock-in (KI) models--Sca1154Q/2Q and Sca7266Q/5Q mice. Keywords: comparative disesae state analysis between Sca1154Q/2Q and Sca7266Q/5Q knock-in cerebellum

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Decreasing Mutant ATXN1 Nuclear Localization Improves a Spectrum of SCA1-Like Phenotypes and Brain Region Transcriptomic Profiles

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