Regulation of autophagy and aggregate-prone proteins by deubiquitinating enzymes

Protein homeostasis (proteostasis) impairment is correlated with the accumulation of toxic misfolded aggregate-prone proteins, such as mutant huntingtin in Huntington’s disease and alpha-synuclein in Parkinson`s disease. Autophagy is a key pathway for the degradation of aggregate-prone proteins. We showed that the deubiquitinating enzyme (DUB), ataxin-3 enables autophagy in neurons by protecting the autophagy protein beclin 1 from degradation in the proteasome (Ashkenazi A. et al. Nature, 2017). This mechanism was abrogated by different polyglutamine disease proteins, including mutant huntingtin highlighting the importance of DUBs in neuronal proteostasis. In the Ashkenazi’s lab, we focus on ubiquitin signaling and the degradation of misfolded proteins (Galves M. et al., Trends in Biochemical Sciences, 2019). We are initiating a loss-of-function screen targeting all human DUBs in neuronal cells expressing the fluorescently labeled autophagy substrates, mutant huntingtin, and alpha-synuclein. By monitoring fluorescence in flow cytometry, we aim to uncover new DUBs that regulate the levels of the misfolded proteins. Our screen setup also allows clearance experiments in the stable-inducible cells. The DUBs will be investigated mechanistically in neurons for the regulation of autophagy with the goal of finding new pathways that promote neuron survival.