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Therapeutic effects of ASO-mediated reduction of Atxn1 in a SCA1 Mouse Mode: Proof of concept with distinct disease-associated transcriptome profiles in cerebellum and medulla

ABSTRACT: RNA-targeting approaches have improved disease symptoms in preclinical rodent models of several neurological diseases. Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited ataxia caused by expansion of a polyglutamine tract in the encoded protein Ataxin-1 (ATXN1). Despite advances in understanding this CAG repeat/polyglutamine expansion disease, there are still no therapies to alter its progressive fatal course. Here we investigate the therapeutic capability of an antisense oligonucleotide (ASO) targeting mouse Atxn1 in Atxn 1 154Q/2Q knockin mice that manifest motor deficits and premature lethality. Following a single ASO treatment at 5 weeks of age, mice demonstrated rescue of these disease-associated phenotypes. In addition, RNA-seq on vehicle-treated Atxn1 154Q/2Q and ASO-treated Atxn1 154Q/2Q mice were used to demonstrate molecular differences between SCA1 pathogenesis in the cerebellum that underlies ataxia with disease in the medulla associated with lethality. Together, these findings support the efficacy and therapeutic importance of directly targeting ATXN1 expression as a strategy to rescue both motor deficits and lethality seen in SCA1.

ORGANISM(S): Mus musculus

PROVIDER: GSE114674 | GEO | 2019/05/31

REPOSITORIES: GEO

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Project description:Spinocerebellar ataxia type 6 (SCA6) is a dominantly inherited neurodegenerative disease caused by an expansion of a CAG repeat encoding a polyglutamine (PolyQ) tract in the Cav2.1 voltage-gated calcium channel. Pathologically, it is characterized by selective degeneration of cerebellar Purkinje cells (PCs), which are a common target for PolyQ-induced toxicity among several different SCAs. Mutant Cav2.1 confers toxicity mainly through a toxic gain-of-function mechanism, but subcellular site of expanded Cav2.1 toxicity is controversial and it remains elusive whether SCA6 shares pathogenic cascades with other SCAs. To gain insight into these problems, we studied the cerebellar gene expression patterns of young Sca6 MPI 118Q/118Q knockin (KI) mice, which express mutant Cav2.1 from endogenous locus and faithfully models human SCA6. Comparison of transcriptional changes with those of Sca1 154Q/2Q mice, a faithful KI mouse model of SCA1, revealed that transcriptional signatures in the MPI 118Q/118Q were distinct from those of Sca1 154Q/2Q. Examination of temporal profiles of candidate genes showed that upregulation of those associated with microglial activation was initiated before PC degeneration was apparent and augmented as the disease progressed. Histological analysis of the MPI 118Q/118Q cerebellum confirmed the presence of Iba-1 positive activated microglia. Moreover, predominance of M1-like pro-inflammatory microglia was observed and was concomitant with the increased expression of pro-inflammatory cytokines. These results suggest that the unique transcriptional response, which highlights upregulation of neuroinflammatory genes possibly associated with lysosomal involvement, may play a pivotal role in the pathogenesis. Modulation of innate immune system could pave the way for slowing the progression of SCA6. We used MPI 118Q/118Q and MPI 11Q/11Q mice for Sca6 KI model at six weeks old. Statistical analysis of differently expressed genes was performed using the Linear Models for Microarray Data (limma) package in R/Bioconductor.

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Therapeutic effects of ASO-mediated reduction of Atxn1 in a SCA1 Mouse Mode: Proof of concept with distinct disease-associated transcriptome profiles in cerebellum and medulla

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