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Protein phosphatase 1 regulates huntingtin exon 1 aggregation and toxicity

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journal contribution
posted on 06.07.2017, 14:40 by Joana Branco-Santos, Federico Herrera, Gonçalo M. Poças, Yolanda Pires-Afonso, Flaviano Giorgini, Pedro M. Domingos, Tiago F. Outeiro
Huntington’s disease (HD) is neurodegenerative disorder caused by a polyglutamine expansion in the N-terminal region of the huntingtin protein (N17). Here, we analysed the relative contribution of each phosphorylatable residue in the N17 region (T3, S13 and S16) towards huntingtin exon 1 (HTTex1) oligomerization, aggregation and toxicity in human cells and Drosophila neurons. We used bimolecular fluorescence complementation (BiFC) to show that expression of single phosphomimic mutations completely abolished HTTex1 aggregation in human cells. In Drosophila, Mimicking phosphorylation at T3 decreased HTTex1 aggregation both in larvae and adult flies. Interestingly, pharmacological or genetic inhibition of protein phosphatase 1 (PP1) prevented HTTex1 aggregation in both human cells and Drosophila while increasing neurotoxicity in flies. Our findings suggest that PP1 modulates HTTex1 aggregation by regulating phosphorylation on T3. In summary, our study suggests that modulation of HTTex1 single phosphorylation events by PP1 could constitute an efficient and direct molecular target for therapeutic interventions in HD.


The authors thank the Bloomington Drosophila Stock Center and the Developmental Studies Hybridoma Bank for fly stocks and antibodies, respectively. The authors also thank Bioimaging Unit from Instituto de Medicina Molecular and Advance Imaging Unit from Gulbenkian Science Institute for support with imaging. TFO and FH were supported by a seed grant from the European Huntington Disease Network (EHDN). TFO is currently supported by the DFG Center for Nanoscale Microscopy and Molecular Physiology of the Brain. FH and PMD were also supported by Project LISBOA-01-0145-FEDER-007660 (Cellular Structural and Molecular Microbiology) funded by FEDER funds through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) and by national funds through Fundação para a Ciência e Tecnologia (Refs. SFRH/BPD/63530/2009, IF/00094/2013/CP1173/CT0005 and UID/CBQ/04612/2013). JBS was supported by Fundação para a Ciência e a Tecnologia (Ref. SFRH/BD/85275/2012) and FCT/MCTES (Ref. CBQ/04612/ICL3535, to FH and PMD). PMD, GMP and YPA were also supported by Fundação para a Ciência e a Tecnologia (FCT-ANR/NEUNMC/0006/2013 and PTDC/NEU-NMC/2459/2014). FG thanks the Medical Research Council (MRC) for funding that provided valuable infrastructure supporting this work.



Human Molecular Genetics, 2017, ddx260

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/Organisation/COLLEGE OF MEDICINE, BIOLOGICAL SCIENCES AND PSYCHOLOGY/MBSP Non-Medical Departments/Department of Genetics


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Human Molecular Genetics


Oxford University Press (OUP)





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