Journal
JOURNAL OF MOLECULAR NEUROSCIENCE
Volume 50, Issue 3, Pages 586-599Publisher
SPRINGERNATURE
DOI: 10.1007/s12031-013-0012-x
Keywords
Polyglutamine; Neurodegeneration; Autophagy; p53; FIP200; ULK1
Categories
Funding
- Swedish Research Council [90274201]
- Harald Jeanssons stiftelse
- Harald och Greta Jeanssons stiftelse
- Magn Bergvalls stiftelse
- O.E. och Edla Johanssons vetenskapliga stiftelse
- Ahlen stiftelsen
- Goljes stiftelse
- Swedish Association of Persons with Neurological Disabilities
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Spinocerebellar ataxia type 7 (SCA7) is one of nine neurodegenerative disorders caused by expanded polyglutamine domains. These so-called polyglutamine (polyQ) diseases are all characterized by aggregation. Reducing the level of aggregating polyQ proteins via pharmacological activation of autophagy has been suggested as a therapeutic approach. However, recently, evidence implicating autophagic dysfunction in these disorders has also been reported. In this study, we show that the SCA7 polyglutamine protein ataxin-7 (ATXN7) reduces the autophagic activity via a previously unreported mechanism involving p53-mediated disruption of two key proteins involved in autophagy initiation. We show that in mutant ATXN7 cells, an increased p53-FIP200 interaction and co-aggregation of p53-FIP200 into ATXN7 aggregates result in decreased soluble FIP200 levels and subsequent destabilization of ULK1. Together, this leads to a decreased capacity for autophagy induction via the ULK1-FIP200-Atg13-Atg101 complex. We also show that treatment with a p53 inhibitor, or a blocker of ATXN7 aggregation, can restore the soluble levels of FIP200 and ULK1, as well as increase the autophagic activity and reduce ATXN7 toxicity. Understanding the mechanism behind polyQ-mediated inhibition of autophagy is of importance if therapeutic approaches based on autophagy stimulation should be developed for these disorders.
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