Neurotoxicity of the Parkinson Disease-Associated Pesticide Ziram Is Synuclein-Dependent in Zebrafish Embryos

Abstract

Background:Exposure to the commonly used dithiocarbamate (DTC) pesticides is associated with an increased risk of developing Parkinson disease (PD), although the mechanisms by which they exert their toxicity are not completely understood.Objective:We studied the mechanisms of ziram’s (a DTC fungicide) neurotoxicity in vivo.Methods:Zebrafish (ZF) embryos were utilized to determine ziram’s effects on behavior, neuronal toxicity, and the role of synuclein in its toxicity.Results:Nanomolar-range concentrations of ziram caused selective loss of dopaminergic (DA) neurons and impaired swimming behavior. Because ziram increases α-synuclein (α-syn) concentrations in rat primary neuronal cultures, we investigated the effect of ziram on ZF γ-synuclein 1 (γ1). ZF express 3 synuclein isoforms, and ZF γ1 appears to be the closest functional homologue to α-syn. We found that recombinant ZF γ1 formed fibrils in vitro, and overexpression of ZF γ1 in ZF embryos led to the formation of neuronal aggregates and neurotoxicity in a manner similar to that of α-syn. Importantly, knockdown of ZF γ1 with morpholinos and disruption of oligomers with the molecular tweezer CLR01 prevented ziram’s DA toxicity.Conclusions:These data show that ziram is selectively toxic to DA neurons in vivo, and this toxicity is synuclein-dependent. These findings have important implications for understanding the mechanisms by which pesticides may cause PD.Citation:Lulla A, Barnhill L, Bitan G, Ivanova MI, Nguyen B, O’Donnell K, Stahl MC, Yamashiro C, Klärner FG, Schrader T, Sagasti A, Bronstein JM. 2016. Neurotoxicity of the Parkinson disease-associated pesticide ziram is synuclein-dependent in zebrafish embryos. Environ Health Perspect 124:1766–1775; http://dx.doi.org/10.1289/EHP141

Molecular tweezers for lysine and arginine – powerful inhibitors of pathologic protein aggregation

“…110 In a new study, Ziram was found to be highly toxic in wild-type ZF embryos and the toxicity seemed to be specific to aminergic neurons (including dopaminergic neurons). Addition of CLR01 had a strong protective effect against Ziram toxicity (Figure 7B), 111 presumably through a similar mechanism as observed in the ZF expressing human α-synuclein.…”

Inhibition of Mutant αB Crystallin‐Induced Protein Aggregation by a Molecular Tweezer

“…CLR01 acts as a nanochaperone using selective binding to lysine by a combination of hydrophobic and electrostatic interactions, which are important in aberrant protein self‐assembly . CLR01 suppressed α‐synuclein fibril assembly and disaggregated preformed fibrils in neurons, rescuing the animal's neurodegenerative phenotype and promoting survival in zebrafish embryos expressing human α‐synuclein or treated with the Parkinson disease–linked pesticide Ziram . Similarly, it reduced α‐synuclein accumulation and aggregation and promoted neuron survival in a lamprey model of spinal‐cord injury .…”

The molecular tweezer CLR01 inhibits Ebola and Zika virus infection

“…In fact, CLR01 prevents assembly and promotes disaggregation of amyloid fibrils that are associated with neurodegenerative diseases Ferreira et al, 2014;Prabhudesai et al, 2012;Richter et al, 2017). Therapeutic effects of CLR01 have been demonstrated in animal models of Parkinson's disease (Lulla, 2016;Prabhudesai et al, 2012;Richter et al, 2017), Alzheimer's disease Malik et al, 2017), Familial Amyloidotic Polyneuropathy (FAP) (Ferreira et al, 2014), and desmin-related cardiomyopathy and was found to be safe in mice at doses 250-times higher than those showing therapeutic effects . We have recently established that CLR01 also disrupted the formation of amyloid fibrils in semen (Lump et al, 2015), which enhance HIV-1 infection (Münch et al, 2007;Usmani et al, 2014).…”