E46K mutant ?-synuclein is more degradation resistant and exhibits greater toxic effects than wild-type ?-synuclein in Drosophila models of Parkinson's disease.

ABSTRACT: Parkinson's disease (PD) is one of the most common neurodegenerative diseases, which is characterized by progressive motor dysfunction as well as non-motor symptoms. Pathological and genetic studies have demonstrated that ?-synuclein (?Syn) plays key roles in the pathogenesis of PD. Although several missense mutations in the ?Syn gene have been identified as causes of familial PD, the mechanisms underlying the variance in the clinical phenotypes of familial PD caused by different mutations remain elusive. Here, we established novel Drosophila models expressing either wild-type (WT) ?Syn or one of five ?Syn mutants (A30P, E46K, H50Q, G51D, and A53T) using site-specific transgenesis, which express transgenes at equivalent levels. Expression of either WT or mutant ?Syn in the compound eyes by the GMR-GAL4 driver caused mild rough eye phenotypes with no obvious difference among the mutants. Upon pan-neuronal expression by the nSyb-GAL4 driver, these ?Syn-expressing flies showed a progressive decline in locomotor function. Notably, we found that E46K, H50Q, G51D, and A53T ?Syn-expressing flies showed earlier onset of locomotor dysfunction than WT ?Syn-expressing flies, suggesting their enhanced toxic effects. Whereas mRNA levels of WT and mutant ?Syn were almost equivalent, we found that protein expression levels of E46K ?Syn were higher than those of WT ?Syn. In vivo chase experiments using the drug-inducible GMR-GeneSwitch driver demonstrated that degradation of E46K ?Syn protein was significantly slower than WT ?Syn protein, indicating that the E46K ?Syn mutant gains resistance to degradation in vivo. We therefore conclude that our novel site-specific transgenic fly models expressing either WT or mutant ?Syn are useful to explore the mechanisms by which different ?Syn mutants gain toxic functions in vivo.

SUBMITTER: Sakai R 

PROVIDER: S-EPMC6594597 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature