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Rab8 Promotes Mutant HTT Aggregation, Reduces Neurodegeneration, and Ameliorates Behavioural Alterations in a Drosophila Model of Huntington's Disease

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journal contribution
posted on 2020-11-23, 10:53 authored by Laura Delfino, Robert P Mason, Charalambos P Kyriacou, Flaviano Giorgini, Ezio Rosato
BACKGROUND: Altered cellular vesicle trafficking has been linked to the pathogenesis of Huntington's disease (HD), a fatal, inherited neurodegenerative disorder caused by mutation of the huntingtin (HTT) protein. The Rab GTPase family of proteins plays a key role in regulation of vesicle trafficking, with distinct Rabs helping specify membrane identity and mediating cellular processes including budding, motility and tethering of vesicles to their targets. In recent years several Rab GTPases-notably, Rab5 and Rab11-have been linked to the pathogenesis of neurodegenerative disorders, including HD. OBJECTIVE: We investigated whether Rab8, which regulates post-Golgi vesicle trafficking, is able to improve HD-relevant phenotypes in a well-characterised model. METHODS: We overexpressed Rab8 in a Drosophila model of HD testing cellular, behavioural, and molecular phenotypes. RESULTS: We found that Rab8 overexpression ameliorated several disease-related phenotypes in fruit flies expressing a mutant HTT fragment throughout the nervous system, including neurodegeneration of photoreceptor neurons, reduced eclosion of the adult fly from the pupal case and shortened lifespan. Rab8 overexpression also normalised aberrant circadian locomotor behaviour in flies expressing mutant HTT in a specific population of neurons that regulate the circadian clock. Intriguingly, expression of Rab8 increased the accumulation of SDS-insoluble aggregated species of mutant HTT. CONCLUSION: Collectively, our findings demonstrate that increased Rab8 levels protect against mutant HTT toxicity and potentiate its aggregation, likely reducing the accumulation of downstream toxic soluble species.

History

Citation

Journal of Huntington's Disease, vol. 9, no. 3, pp. 253-263, 2020

Author affiliation

Department of Genetics and Genome Biology

Version

  • AM (Accepted Manuscript)

Published in

Journal of Huntington's Disease

Volume

9

Issue

3

Pagination

253 - 263

Publisher

IOS Press

issn

1879-6397

eissn

1879-6400

Copyright date

2020

Available date

2020-10-08

Spatial coverage

Netherlands

Language

English