ABSTRACT
Mutations in leucine-rich repeat kinase 2 (LRRK2) and α-synuclein lead to Parkinson's disease (PD). Disruption of protein homeostasis is an emerging theme in PD pathogenesis, making mechanisms to reduce the accumulation of misfolded proteins an attractive therapeutic strategy. We determined if activating nuclear factor erythroid 2-related factor (Nrf2), a potential therapeutic target for neurodegeneration, could reduce PD-associated neuron toxicity by modulating the protein homeostasis network. Using a longitudinal imaging platform, we visualized the metabolism and location of mutant LRRK2 and α-synuclein in living neurons at the single-cell level. Nrf2 reduced PD-associated protein toxicity by a cell-autonomous mechanism that was time-dependent. Furthermore, Nrf2 activated distinct mechanisms to handle different misfolded proteins. Nrf2 decreased steady-state levels of α-synuclein in part by increasing α-synuclein degradation. In contrast, Nrf2 sequestered misfolded diffuse LRRK2 into more insoluble and homogeneous inclusion bodies. By identifying the stress response strategies activated by Nrf2, we also highlight endogenous coping responses that might be therapeutically bolstered to treat PD.
Subject(s)
Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/antagonists & inhibitors , NF-E2-Related Factor 2/physiology , Nerve Tissue Proteins/metabolism , Neurons/drug effects , Parkinson Disease/metabolism , alpha-Synuclein/antagonists & inhibitors , Animals , Cerebral Cortex/cytology , Genes, Reporter , HEK293 Cells , Humans , Hydroquinones/pharmacology , Inclusion Bodies , Induced Pluripotent Stem Cells/cytology , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/metabolism , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/toxicity , NF-E2-Related Factor 2/biosynthesis , NF-E2-Related Factor 2/genetics , Neurons/metabolism , Primary Cell Culture , Protein Aggregation, Pathological , Proteostasis , Rats , Recombinant Fusion Proteins/metabolism , Single-Cell Analysis , Time Factors , alpha-Synuclein/metabolism , alpha-Synuclein/toxicityABSTRACT
A common genetic form of Parkinson's disease (PD) is caused by mutations in LRRK2. We identify WSB1 as a LRRK2 interacting protein. WSB1 ubiquitinates LRRK2 through K27 and K29 linkage chains, leading to LRRK2 aggregation and neuronal protection in primary neurons and a Drosophila model of G2019S LRRK2. Knocking down endogenous WSB1 exacerbates mutant LRRK2 neuronal toxicity in neurons and the Drosophila model, indicating a role for endogenous WSB1 in modulating LRRK2 cell toxicity. WSB1 is in Lewy bodies in human PD post-mortem tissue. These data demonstrate a role for WSB1 in mutant LRRK2 pathogenesis, and suggest involvement in Lewy body pathology in sporadic PD. Our data indicate a role in PD for ubiquitin K27 and K29 linkages, and suggest that ubiquitination may be a signal for aggregation and neuronal protection in PD, which may be relevant for other neurodegenerative disorders. Finally, our study identifies a novel therapeutic target for PD.
