Calpain inhibition reduces ataxin-3 cleavage alleviating neuropathology and motor impairments in mouse models of Machado-Joseph disease.

Ana Teresa Simões, Nélio Gonçalves, Rui Jorge Nobre, Carlos Bandeira Duarte, Luís Pereira de Almeida

Index: Hum. Mol. Genet. 23(18) , 4932-44, (2014)

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Abstract

Machado-Joseph Disease (MJD) is the most prevalent autosomal dominantly inherited cerebellar ataxia. It is caused by an expanded CAG repeat in the ATXN3 gene, which translates into a polyglutamine tract within the ataxin-3 protein. Present treatments are symptomatic and do not prevent disease progression. As calpain overactivation has been shown to contribute to mutant ataxin-3 proteolysis, translocation to the nucleus, inclusions formation and neurodegeneration, we investigated the potential role of calpain inhibition as a therapeutic strategy to alleviate MJD pathology. For this purpose, we administered orally the calpain inhibitor BDA-410 to a lentiviral mouse model of MJD. Western-blot and immunohistochemical analysis revealed the presence of N- and C-terminal mutant ataxin-3 fragments and the colocalization of large inclusions with cleaved caspase-3 in the mice brain. Oral administration of the calpain inhibitor BDA-410 decreased both fragments formation and full-length ataxin-3 levels, reduced aggregation of mutant ataxin-3 and prevented cell injury and striatal and cerebellar degeneration. Importantly, in correlation with the preserved cerebellar morphology, BDA-410 prevented motor behavioural deficits. In conclusion, BDA-410 alleviates Machado-Joseph neuropathology and may therefore be an effective therapeutic option for MJD. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.