Branco-Santos Joana, Herrera Federico, Poças Gonçalo M, Pires-Afonso Yolanda, Giorgini Flaviano, Domingos Pedro M, Outeiro Tiago F
Laboratory of Cell Structure and Dynamics, Instituto de Tecnologia Química e Biológica, Oeiras, Portugal.
Laboratory of Cell Signaling in Drosophila, Instituto de Tecnologia Química e Biológica, Oeiras, Portugal.
Hum Mol Genet. 2017 Oct 1;26(19):3763-3775. doi: 10.1093/hmg/ddx260.
Huntington's disease 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 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 Huntington's disease.
亨廷顿舞蹈症是一种神经退行性疾病，由亨廷顿蛋白（N17）N端区域的多聚谷氨酰胺扩增引起。在此，我们分析了N17区域（T3、S13和S16）中每个可磷酸化残基对人细胞和果蝇神经元中亨廷顿蛋白外显子1（HTTex1）寡聚化、聚集及毒性的相对贡献。我们利用双分子荧光互补技术表明，单个磷酸模拟突变的表达完全消除了人细胞中HTTex1的聚集。在果蝇中，模拟T3位点的磷酸化可减少幼虫和成年果蝇中HTTex1的聚集。有趣的是，蛋白磷酸酶1（PP1）的药理学或遗传学抑制可防止人细胞和果蝇中HTTex1的聚集，同时增加果蝇的神经毒性。我们的研究结果表明，PP1通过调节T3位点的磷酸化来调控HTTex1的聚集。总之，我们的研究表明，PP1对HTTex1单个磷酸化事件的调节可能构成亨廷顿舞蹈症治疗干预的一个有效且直接的分子靶点。
