The Nt17 Domain and its Helical Conformation Regulate the Aggregation, Cellular Properties and Neurotoxicity of Mutant Huntingtin Exon 1.

Autor: Vieweg S; Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland., Mahul-Mellier AL; Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland., Ruggeri FS; Laboratory of the Physics of Living Matter, EPFL, 1015 Lausanne, Switzerland., Riguet N; Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland., DeGuire SM; Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland., Chiki A; Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland., Cendrowska U; Laboratory of the Physics of Living Matter, EPFL, 1015 Lausanne, Switzerland., Dietler G; Laboratory of the Physics of Living Matter, EPFL, 1015 Lausanne, Switzerland., Lashuel HA; Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland. Electronic address: hilal.lashuel@epfl.ch.
Jazyk: angličtina
Zdroj: Journal of molecular biology [J Mol Biol] 2021 Oct 15; Vol. 433 (21), pp. 167222. Date of Electronic Publication: 2021 Sep 04.
DOI: 10.1016/j.jmb.2021.167222
Abstrakt: Converging evidence points to the N-terminal domain comprising the first 17 amino acids of the Huntingtin protein (Nt17) as a key regulator of its aggregation, cellular properties and toxicity. In this study, we further investigated the interplay between Nt17 and the polyQ domain repeat length in regulating the aggregation and inclusion formation of exon 1 of the Huntingtin protein (Httex1). In addition, we investigated the effect of removing Nt17 or modulating its local structure on the membrane interactions, neuronal uptake, and toxicity of monomeric or fibrillar Httex1. Our results show that the polyQ and Nt17 domains synergistically modulate the aggregation propensity of Httex1 and that the Nt17 domain plays important roles in shaping the surface properties of mutant Httex1 fibrils and regulating their poly-Q-dependent growth, lateral association and neuronal uptake. Removal of Nt17 or disruption of its transient helical conformations slowed the aggregation of monomeric Httex1 in vitro, reduced inclusion formation in cells, enhanced the neuronal uptake and nuclear accumulation of monomeric Httex1 proteins, and was sufficient to prevent cell death induced by Httex1 72Q overexpression. Finally, we demonstrate that the uptake of Httex1 fibrils into primary neurons and the resulting toxicity are strongly influenced by mutations and phosphorylation events that influence the local helical propensity of Nt17. Altogether, our results demonstrate that the Nt17 domain serves as one of the key master regulators of Htt aggregation, internalization, and toxicity and represents an attractive target for inhibiting Htt aggregate formation, inclusion formation, and neuronal toxicity.
Competing Interests: Acknowledgments This work was supported by funding from EPFL, the Cure Huntington's Disease Initiative (CHDI) foundation and the Swiss National Science Foundation (SFN). We are grateful to the Biological Electron Microscopy facility (EPFL) and the Bio-imaging Core Facility (EPFL) for their technical support and helpful discussions. We thank Dr. Davide Demurtas (CIME core facility, EPFL) for imaging the fibrils shown in Figure 3D by cryo-EM. We thank Dr. Romain Guiet for his help in developing the distance map script and Mary Croisier for the acquisition of the CLEM images. We also deeply thank Sergey Nazarov for his inputs and help in drawing the final model in the graphical abstract. Author contributions H.A.L. conceived and supervised the study. H.A.L, S.V., A.L.M.M., F.S.R. and N.R. wrote the paper. S.V. designed, performed and analyzed the experiments shown in Figures 1–3,S1-S6, S8 and S12. A.L.M.M. designed, performed and analyzed the experiments shown in Figures 4–7, S7, S9-S11 and S13. F.S.R designed, performed and analyzed the experiments shown in Figures 1(B), 2(B)-(C) and S4-S5. N.R. performed, analyzed and plotted the experiments shown in Figures 4–7, Figures S7, S9-S11 and S13. S.D. and A.C. prepared and fully characterized the phosphorylated Httex1 proteins used in Figures 6 and 7(D). U.C. performed and analyzed the experiments shown in Figures 1(B), 2(B)-(C), S4-S5, S8 and S12. G.D. supervised the experiments shown in Figures 1(B), 2(B)-(C) and S4-S5. All authors reviewed and contributed to the writing.
(Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)
Databáze: MEDLINE
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