Inhibition of Autophagy via p53-Mediated Disruption of ULK1 in a SCA7 Polyglutamine Disease Model [Elektronisk resurs]

• 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. 

Ämnesord

Natural Sciences  (hsv)

Chemical Sciences  (hsv)

Naturvetenskap  (hsv)

Kemi  (hsv)

Natural Sciences  (hsv)

Biological Sciences  (hsv)

Naturvetenskap  (hsv)

Biologiska vetenskaper  (hsv)

neurokemi med molekylär neurobiologi  (su)

Neurochemistry with Molecular Neurobiology  (su)