Treatment with sodium butyrate has therapeutic benefits for Machado-Joseph disease through the induction of autophagy

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 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. Interestingly, treatment with SB decreased the size of detergentinsoluble ataxin-3 aggregates in vitro . Further investigation revealed that SB treatment increased activity of the autophagy protein quality control pathway in the MJD cells and decreased presence of ataxin-3 oligomers in an autophagy-dependent manner. Treatment with SB was also beneficial in vivo through induction of autophagy and improving swimming performance in transgenic MJD zebrafish. Co-treating the MJD zebrafish with SB and chloroquine, an autophagy inhibitor, prevented the beneficial effects of SB, suggesting that the improved swimming performance was autophagy-dependent. Furthermore, intraperitoneal injection of SB to wild type mice resulted in increased levels of neuronal LC3B levels, indicating induction of autophagy within the brain. Collectively, our findings suggest that SB can induce activity of the autophagy pathway and can produce 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. ### Competing Interest Statement The authors have declared no competing interest. * MJD : Machado-Joseph disease HDAC : histone deacetylase polyQ : polyglutamine SB : sodium butyrate dpf : days post fertilization EGFP : enhanced green fluorescent protein FSC : forward scatter signal H3K9 : acetylated histone 3 at lysine 9 H4K5 : acetylated histone 4 at lysine 5