Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of mouse spinocerebellar ataxia type 3 (SCA3) transgenic and wild type animals treated with CCI-779 or placebo

ABSTRACT: Spinocerebellar ataxia type 3 is a neurodegenerative disorder caused by the expansion of the polyglutamine repeat region within the ataxin-3 protein. The mutant protein forms intracellular aggregates in the brain. However, the cellular mechanisms causing toxicity are still poorly understood and there are currently no effective treatments. In this study we show that administration of a rapamycin ester, CCI-779, improves motor performance in a transgenic mouse model of SCA3. CCI-779 inhibits mammalian target of rapamycin (mTOR) and hence upregulates protein degradation by autophagy. CCI-779 reduces the number of aggregates seen in the brains of transgenic mice and decreases levels of cytosolic soluble mutant ataxin-3, while endogenous wild-type protein levels remain unaffected. CCI-779 is designed for long-term use in patients and therefore represents a possible therapeutic strategy for the treatment of SCA3. Using this disease model and treatment paradigm we employed a microarray approach to investigate transcriptional changes that might be important in the pathogenesis of SCA3. This approach identified Usp15, which showed expression changes at both the mRNA and protein level. Usp15 levels were also changed in mice expressing another mutant polyglutamine protein, huntingtin. In total we identified 16 transcripts that were decreased in transgenic ataxin-3 mice that were normalised following CCI-779 treatment, as the number of transcripts changed was low and the magnitude of these changes was small we suggest that transcriptional dysregulation may not be an important step in the primary pathogenesis of SCA3. Experiment Overall Design: We analyzed 19 brain samples in total. 4 samples from wt animals after placebo treatment. 5 samples from wt animals after CCI-779 treatment. 5 samples from SCA3 tg animals after placebo treatment. 5 samples from SCA3 tg animals after CCI-779 treatment.

ORGANISM(S): Mus musculus

SUBMITTER: Michael Bonin

PROVIDER: E-GEOD-17994 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Machado-Joseph disease (MJD) is a fatal neurodegenerative disease caused by expansion of the trinucleotide repeat region within the ATXN3/MJD gene. Mutation of ATXN3 causes formation of neurotoxic ataxin-3 protein aggregates, neurodegeneration and motor deficits. Here we investigated the therapeutic potential and mechanistic activity of sodium butyrate (SB), the sodium salt of butyric acid, a metabolite naturally produced by gut microbiota, on cultured SH-SY5Y cells and transgenic zebrafish expressing human ataxin-3 containing 84 glutamine (Q) residues to model MJD. MJD SH-SY5Y cells were found to contain ataxin-3 oligomeric species and protein aggregates. Treatment with SB increased activity of the autophagy protein quality control pathway in the MJD cells, decreased presence of ataxin-3 aggregates and presence of ataxin-3 oligomers in an autophagy-dependent manner. Treatment with SB was also beneficial in vivo, improving swimming performance, increasing autophagy activity and decreasing presence of insoluble ataxin-3 protein species in the transgenic MJD zebrafish. Co-treating the MJD zebrafish with SB and chloroquine, an autophagy inhibitor, prevented the beneficial effects of SB on the zebrafish swimming, suggesting that the improved swimming performance was autophagy-dependent. To identify mechanism of the induction of autophagy by SB, we performed proteomic analysis of protein lysates from the SB treated and untreated MJD SH-SY5Y cells. We found that SB treatment had increased activity of Protein Kinase A and AMPK signaling. Immunoblot analysis confirmed that SB treatment had increased levels of acetylated FOXO1 protein. Further, co-treatment with an inhibitor of FOXO1 transcriptional activity (AS1842856) prevented the increase in autophagosome formation (LC3II/I) usually produced by SB treatment. Together our findings indicate that treatment with SB can increase activity of the autophagy pathway through a FOXO1-dependent process and that this has beneficial effects in vitro and in vivo. We propose that treatment with sodium butyrate warrants further investigation for the treatment of neurodegenerative diseases underpinned by proteinopathy mechanisms, including MJD.

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Transcription profiling of mouse spinocerebellar ataxia type 3 (SCA3) transgenic and wild type animals treated with CCI-779 or placebo

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