Beclin1 decreases the RIPA-insoluble fraction of amyotrophic lateral sclerosis-linked SOD1 mutant via autophagy

Abstract

Many neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), are characterised by the intracellular appearance of protein aggregates or insoluble materials. Accelerated removal of related toxic proteins might be beneficial for these diseases. Here we describe an inducible role of Beclin1, an essential regulator for autophagy, in degradation of the familial ALS-linked Cu/Zn superoxide dismutase 1 (SOD1) mutant. We confirmed that the SOD1 mutant exhibited an increased RIPA (radioimmune precipitation assay buffer, containing NP40 and sodium deoxycholate)-insolubility compared with SOD1 wild-type (WT). Also, the insoluble fraction formed by SOD1 mutant was greatly reduced by coexpressing Beclin1 in both neuronal and non-neuronal cell lines. Pharmacological inhibition of autophagy diminished the effect of Beclin1 and resulted in an accumulation of insoluble SOD1. Our results support the role of Beclin1 in the involvement of autophagic degradation of SOD1 mutant. We propose Beclin1 enhances autophagy and presents a possible therapeutic strategy for familial ALS.