Differential degradation of full-length and cleaved ataxin-7 fragments in a novel stable inducible SCA7 model
2012 (English)In: Journal of Molecular Neuroscience, ISSN 0895-8696, E-ISSN 1559-1166, Vol. 47, no 2, 219-233 p.Article in journal (Refereed) Published
Spinocerebellar ataxia type 7 (SCA7) is one of nine neurodegenerative disorders caused by expanded polyglutamine repeats, and a common toxic gain-of-function mechanism has been proposed. Proteolytic cleavage of several polyglutamine proteins has been identified and suggested to modulate the polyglutamine toxicity. In this study, we show that full-length and cleaved fragments of the SCA7 disease protein ataxin-7 (ATXN7) are differentially degraded. We found that the ubiquitin-proteosome system (UPS) was essential for the degradation of full-length endogenous ATXN7 or transgenic full-length ATXN7 with a normal or expanded glutamine repeat in both HEK 293T and stable PC12 cells. However, a similar contribution by UPS and autophagy was found for the degradation of proteolytically cleaved ATXN7 fragments. Furthermore, in our novel stable inducible PC12 model, induction of mutant ATXN7 expression resulted in toxicity and this toxicity was worsened by inhibition of either UPS or autophagy. In contrast, pharmacological activation of autophagy could ameliorate the ATXN7-induced toxicity. Based on our findings, we propose that both UPS and autophagy are important for the reduction of mutant ataxin-7-induced toxicity, and enhancing ATXN7 clearance through autophagy could be used as a potential therapeutic strategy in SCA7.
Place, publisher, year, edition, pages
2012. Vol. 47, no 2, 219-233 p.
Aggregation, Ataxin-7, Autophagy, Polyglutamine, Proteasome, SCA7
Biological Sciences Chemical Sciences
Research subject Neurochemistry with Molecular Neurobiology
IdentifiersURN: urn:nbn:se:su:diva-64160DOI: 10.1007/s12031-012-9722-8ISI: 000304567700002OAI: oai:DiVA.org:su-64160DiVA: diva2:455938
FunderSwedish Research Council, K2010-68X-21449-01-3
AuthorCount: 4;2011-11-112011-11-112015-09-24Bibliographically approved