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Suzuki, M., Fujikake, N., Takeuchi, T., Kohyama-Koganeya, A., Nakajima, K., Hirabayashi, Y., Wada, K., Nagai, Y. (2015). Glucocerebrosidase deficiency accelerates the accumulation of proteinase K-resistant α-synuclein and aggravates neurodegeneration in a Drosophila model of Parkinson's disease.  Hum. Mol. Genet. 24(23): 6675--6686.
FlyBase ID
FBrf0230029
Publication Type
Research paper
Abstract

Alpha-synuclein (αSyn) plays a central role in the pathogenesis of Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Recent multicenter genetic studies have revealed that mutations in the glucocerebrosidase 1 (GBA1) gene, which are responsible for Gaucher's disease, are strong risk factors for PD and DLB. However, the mechanistic link between the functional loss of glucocerebrosidase (GCase) and the toxicity of αSyn in vivo is not fully understood. In this study, we employed Drosophila models to examine the effect of GCase deficiency on the neurotoxicity of αSyn and its molecular mechanism. Behavioral and histological analyses showed that knockdown of the Drosophila homolog of GBA1 (dGBA1) exacerbates the locomotor dysfunction, loss of dopaminergic neurons and retinal degeneration of αSyn-expressing flies. This phenotypic aggravation was associated with the accumulation of proteinase K (PK)-resistant αSyn, rather than with changes in the total amount of αSyn, raising the possibility that glucosylceramide (GlcCer), a substrate of GCase, accelerates the misfolding of αSyn. Indeed, in vitro experiments revealed that GlcCer directly promotes the conversion of recombinant αSyn into the PK-resistant form, representing a toxic conformational change. Similar to dGBA1 knockdown, knockdown of the Drosophila homolog of β-galactosidase (β-Gal) also aggravated locomotor dysfunction of the αSyn flies, and its substrate GM1 ganglioside accelerated the formation of PK-resistant αSyn. Our findings suggest that the functional loss of GCase or β-Gal promotes the toxic conversion of αSyn via aberrant interactions between αSyn and their substrate glycolipids, leading to the aggravation of αSyn-mediated neurodegeneration.

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    Language of Publication
    English
    Additional Languages of Abstract
    Parent Publication
    Publication Type
    Journal
    Abbreviation
    Hum. Mol. Genet.
    Title
    Human Molecular Genetics
    Publication Year
    1992-
    ISBN/ISSN
    0964-6906
    Data From Reference
    Alleles (7)
    Genes (5)
    Human Disease Models (1)
    Insertions (1)
    Transgenic Constructs (6)