Journal Article

α-Synuclein accumulates in huntingtin inclusions but forms independent filaments and its deficiency attenuates early phenotype in a mouse model of Huntington's disease

Cristina Tomás-Zapico, María Díez-Zaera, Isidre Ferrer, Pilar Gómez-Ramos, María A. Morán, M. Teresa Miras-Portugal, Miguel Díaz-Hernández and José J. Lucas

in Human Molecular Genetics

Volume 21, issue 3, pages 495-510
Published in print February 2012 | ISSN: 0964-6906
Published online November 2011 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/ddr507
α-Synuclein accumulates in huntingtin inclusions but forms independent filaments and its deficiency attenuates early phenotype in a mouse model of Huntington's disease

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Huntington's disease (HD) is the most common of nine inherited neurological disorders caused by expanded polyglutamine (polyQ) sequences which confer propensity to self-aggregate and toxicity to their corresponding mutant proteins. It has been postulated that polyQ expression compromises the folding capacity of the cell which might affect other misfolding-prone proteins. α-Synuclein (α-syn) is a small neural-specific protein with propensity to self-aggregate that forms Parkinson's disease (PD) Lewy bodies. Point mutations in α-syn that favor self-aggregation or α-syn gene duplications lead to familial PD, thus indicating that increased α-syn aggregation or levels are sufficient to induce neurodegeneration. Since polyQ inclusions in HD and other polyQ disorders are immunopositive for α-syn, we speculated that α-syn might be recruited as an additional mediator of polyQ toxicity. Here, we confirm in HD postmortem brains and in the R6/1 mouse model of HD the accumulation of α-syn in polyQ inclusions. By isolating the characteristic filaments formed by aggregation-prone proteins, we found that N-terminal mutant huntingtin (N-mutHtt) and α-syn form independent filamentous microaggregates in R6/1 mouse brain as well as in the inducible HD94 mouse model and that N-mutHtt expression increases the load of α-syn filaments. Accordingly, α-syn knockout results in a diminished number of N-mutHtt inclusions in transfected neurons and also in vivo in the brain of HD mice. Finally, α-syn knockout attenuates body weight loss and early motor phenotype of HD mice. This study therefore demonstrates that α-syn is a modifier of polyQ toxicity in vivo and raises the possibility that potential PD-related therapies aimed to counteract α-syn toxicity might help to slow HD.

Journal Article.  9511 words.  Illustrated.

Subjects: Genetics and Genomics

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