Summary Parkinson’s disease (PD) is a common neurodegenerative disorder. Functional interactions between some PD genes, like PINK1 and parkin, have been identified, but whether other ones interact remains elusive. Here we report an unexpected genetic interaction between two PD genes, VPS35 and EIF4G1. We provide evidence that EIF4G1 upregulation causes defects associated with protein misfolding. Expression of a sortilin protein rescues these defects, downstream of VPS35, suggesting a potential role for sortilins in PD. We also show interactions between VPS35, EIF4G1 and α–synuclein, a protein with a key role in PD. We extend our findings from yeast to an animal model and show these interactions are conserved in neurons and in transgenic mice. Our studies reveal unexpected genetic and functional interactions between two seemingly unrelated PD genes and functionally connect them to α–synuclein pathobiology in yeast, worms, and mouse. Finally, we provide a resource of candidate PD genes for future interrogation.

Abnormal accumulation and propagation of the neuronal protein α-synuclein has been hypothesized to underlie the pathogenesis of Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. Here we report a de novo-developed compound (NPT100-18A) that reduces α-synuclein toxicity through a novel mechanism that involves displacing α-synuclein from the membrane. This compound interacts with a domain in the C-terminus of α-synuclein. The E83R mutation reduces the compound interaction with the 80-90 amino acid region of α-synuclein and prevents the effects of NPT100-18A. In vitro studies showed that NPT100-18A reduced the formation of wild-type α-synuclein oligomers in membranes, reduced the neuronal accumulation of α-synuclein, and decreased markers of cell toxicity. In vivo studies were conducted in three different α-synuclein transgenic rodent models. Treatment with NPT100-18A ameliorated motor deficits in mThy1 wild-type α-synuclein transgenic mice in a dose-dependent manner at two independent institutions. Neuropathological examination showed that NPT100-18A decreased the accumulation of proteinase K-resistant α-synuclein aggregates in the CNS and was accompanied by the normalization of neuronal and inflammatory markers. These results were confirmed in a mutant line of α-synuclein transgenic mice that is prone to generate oligomers. In vivo imaging studies of α-synuclein-GFP transgenic mice using two-photon microscopy showed that NPT100-18A reduced the cortical synaptic accumulation of α-synuclein within 1 h post-administration. Taken together, these studies support the notion that altering the interaction of α-synuclein with the membrane might be a feasible therapeutic approach for developing new disease-modifying treatments of Parkinson's disease and other synucleinopathies.

Parkinson disease (PD) is the second most common neurodegenerative disorder after Alzheimer disease (AD). There is considerable consensus that the increased production and/or aggregation of ␣-synuclein (␣-syn) plays a central role in the pathogenesis of PD and related synucleinopathies. Current therapeutic strategies for treating PD offer mainly transient symptomatic relief and aim at the restitution of dopamine levels to counterbalance the loss of dopaminergic neurons. Therefore, the identification and development of drug-like molecules that block ␣-synuclein aggregation and prevent the loss of dopaminergic neurons are desperately needed to treat or slow the progression of PD. Here, we show that entacapone and tolcapone are potent inhibitors of ␣-syn and ␤-amyloid (A␤) oligomerization and fibrillogenesis, and they also protect against extracellular toxicity induced by the aggregation of both proteins. Comparison of the anti-aggregation properties of entacapone and tolcapone with the effect of five other catechol-containing compounds, dopamine, pyrogallol, gallic acid, caffeic acid, and quercetin on the oligomerization and fibrillization of ␣-syn and A␤, demonstrate that the catechol moiety is essential for the antiamyloidogenic activity. Our findings present the first characterization of the anti-amyloidogenic properties of tolcapone and entacapone against both ␣-synuclein and A␤42 and highlight the potential of this class of nitro-catechol compounds as antiamyloidogenic agents. Their inhibitory properties, mode of action, and structural properties suggest that they constitute promising lead compounds for further optimization. Parkinson disease (PD)2 is the second most common neurodegenerative disorder after Alzheimer disease (AD), affecting nearly 1-2% of the population 65 years and older. A characteristic early pathological change associated with PD is the selective loss of dopaminergic neurons of the substantia nigra pars compacta and other areas of the brain resulting in the degeneration of the nigro-striatal tract and loss of dopamine (DA) (1). Current therapeutic strategies for treating PD offer mainly transient symptomatic relief by aiming to restore the loss of dopamine by "dopamine replacement therapy." This is accomplished through the administration of levodopa (L-DOPA), a direct precursor of DA and other drugs that increase the lifetime of DA by slowing its metabolism. Catechol O-methyltransferase inhibitors (ICOMT), monoamine oxidase B inhibitors (IMAO B), and peripheral aromatic L-amino acid decarboxylase inhibitors (IAADC) are used as adjunctive medications to L-DOPA to slow DA degradation and increase the availability of brain DA (Scheme

Parkinson's disease and dementia with Lewy bodies are neurodegenerative disorders characterized by accumulation of α-synuclein (α-syn). Recently, single-chain fragment variables (scFVs) have been developed against individual conformational species of α-syn. Unlike more traditional monoclonal antibodies, these scFVs will not activate or be endocytosed by Fc receptors. For this study, we investigated an scFV directed against oligomeric α-syn fused to the LDL receptor-binding domain from apolipoprotein B (apoB). The modified scFV showed enhanced brain penetration and was imported into neuronal cells through the endosomal sorting complex required for transport (ESCRT) pathway, leading to lysosomal degradation of α-syn aggregates. Further analysis showed that the scFV was effective at ameliorating neurodegenerative pathology and behavioral deficits observed in the mouse model of dementia with Lewy bodies/Parkinson's disease. Thus, the apoB modification had the effect of both increasing accumulation of the scFV in the brain and directing scFV/α-syn complexes for degradation through the ESCRT pathway, leading to improved therapeutic potential of immunotherapy.