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

Vieweg, Sophie; Mahul-Mellier, Anne Laure; Ruggeri, Francesco Simone; Riguet, Nathan; DeGuire, Sean M.; Chiki, Anass; Cendrowska, Urszula; Dietler, Giovanni; Lashuel, Hilal A.

doi:10.1016/j.jmb.2021.167222

Cited by 22 publications

(14 citation statements)

References 135 publications

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“…Several studies suggested that the Nt17 domain strongly influenced the structure and the final morphology of the filaments formed by HTTex1. 13,38 Both the polyQ domain and Nt17 promote HTTex1 aggregation in vitro and influence the kinetics of inclusion formation in cells. Previous studies from our group and others have also shown that Nt17 was exposed and flexible in HTTex1 filaments, and recent studies from our group showed that its removal leads to a strong lateral association of the filaments with ribbon-like morphology.…”

Section: T H Imentioning

confidence: 99%

Structural Basis of Huntingtin Fibril Polymorphism Revealed by Cryogenic Electron Microscopy of Exon 1 HTT Fibrils

et al. 2022

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The lack of detailed insight into the structure of aggregates formed by the huntingtin protein (HTT) has hampered the efforts to develop therapeutics and diagnostics targeting pathology formation in the brain of patients with Huntington's disease. To address this knowledge gap, we investigated the structural properties of in vitro-generated fibrils from exon1 of the huntingtin protein by cryogenic electron microscopy and single-particle analyses. We show that wildtype and mutant exon1 of the huntingtin protein form nonhelical fibrils with a polyglutamine amyloid core composed of βhairpins with unique characteristics that have not been previously observed with other amyloid filaments. The stacks of β-hairpins form long planar β-sheets (protofilaments) which combine inter-and intramolecular interactions, with variable stacking angles and occasional out-of-register states of individual β-hairpins. These features and the propensity of protofilaments to undergo lateral association result in a high degree of fibril polymorphisms, including fibrils composed of varying numbers of protofilaments. Our results allow us to speculate on how the flanking domains are organized around the polyglutamine core of the fibril and provide insight into how they might affect the huntingtin fibril structure and polymorphism. The removal of the first 17 amino acids at the N-terminus resulted in surprising intra-fibril structural heterogeneity and reduced fibril's propensity to lateral associations. Overall, this work provides valuable insights that could help guide future mechanistic studies to elucidate the sequence and structural determinants of huntingtin aggregation, as well as for cryo-EM and structural studies of fibrils derived from huntingtin protein and other disease-associated polyglutamine-containing proteins.

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Section: T H Imentioning

confidence: 99%

Structural Basis of Huntingtin Fibril Polymorphism Revealed by Cryogenic Electron Microscopy of Exon 1 HTT Fibrils

et al. 2022

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Section: Production Of Toxic N-terminal Htt Protein Speciesmentioning

confidence: 99%

“…54 Recent in vitro studies by the Lashuel group confirm these results and further extend the findings by showing that the polyQ and Nt17 domains of HTT-ex1 synergistically modulate the aggregation propensity of HTT-ex1, with a key role of the Nt17 domain in regulating HTT-ex1 aggregation dynamics and subcellular localization and toxicity. 34 There is conflicting evidence with regard to the pathogenicity of nuclear and cytoplasmic mHTT. Some groups have reported evidence that nuclear localization is required for toxicity.…”

Section: Properties Of N-terminal Protein Speciesmentioning

confidence: 99%

“…[21][22][23][24][25] Importantly, premature polyadenylation of the pre-mRNA as well as proteolytic cleavage of HTT protein lead to the production of a variety of HTT fragments, and there is ample evidence that such fragments, especially the short N-terminal species, are more toxic than the full-length mHTT protein. [26][27][28][29][30][31][32][33][34][35] In order to make tailored therapeutics towards the short toxic fragments, a good understanding of the mechanisms leading to their formation is needed. In this review, we therefore focus on how toxic N-terminal HTT protein species are produced and how they are linked to toxicity, as well as on therapeutic strategies that are capable of reducing these fragments.…”

Section: Introductionmentioning

confidence: 99%

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Emerging Therapies for Huntington’s Disease – Focus on N-Terminal Huntingtin and Huntingtin Exon 1

Bent¹,

Evers²,

Vallès³

2022

BTT

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Huntington’s disease is a devastating heritable neurodegenerative disorder that is caused by the presence of a trinucleotide CAG repeat expansion in the Huntingtin gene, leading to a polyglutamine tract in the protein. Various mechanisms lead to the production of N-terminal Huntingtin protein fragments, which are reportedly more toxic than the full-length protein. In this review, we summarize the current knowledge on the production and toxicity of N-terminal Huntingtin protein fragments. Further, we expand on various therapeutic strategies targeting N-terminal Huntingtin on the protein, RNA and DNA level. Finally, we compare the therapeutic approaches that are clinically most advanced, including those that do not target N-terminal Huntingtin, discussing differences in mode of action and translational applicability.

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“…Efforts to make stable cell lines by selection after stable transfection were unsuccessful, but to date, expression of this chromobody in transgenic mice has not been attempted. Such a model could be an intriguing way to image huntingtin intravitally and could be an [4], mitotic spindle orientation [10], ER-to nuclear translocation [11], inclusion formation dynamics [41,62,63] Super Resolution Microscopy Fibril morphology [29], sub-nuclear, sub-speckle localization [41], DNA damage repair complexes [12,41] CLARITY R6/2 model whole brain imaging [23] Laser Microirradiation Assays DNA damage complexes with huntingtin [12] Forster Resonant Energy Transfer (FRET) Huntingtin fragment conformational changes [29], HD drug screening [64], huntingtin effects on actin remodeling [82] Correlative Light Electron Microscopy (CLEM) Huntingtin protein inclusions [61] High Content Analysis (HCA) HD drug screening [41,63,64,70,71] Atomic Force Microscopy (AFM) Huntingtin protein inclusions [75][76][77][78]80] resolution 3D imaging of the entire organ. To extend resolution, the diffraction-limit can be…”

mentioning

confidence: 99%

Recent Microscopy Advances and the Applications to Huntington’s Disease Research

Babi

Neuman

Peng

et al. 2022

JHD

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Huntingtin is a 3144 amino acid protein defined as a scaffold protein with many intracellular locations that suggest functions in these compartments. Expansion of the CAG DNA tract in the huntingtin first exon is the cause of Huntington’s disease. An important tool in understanding the biological functions of huntingtin is molecular imaging at the single-cell level by microscopy and nanoscopy. The evolution of these technologies has accelerated since the Nobel Prize in Chemistry was awarded in 2014 for super-resolution nanoscopy. We are in a new era of light imaging at the single-cell level, not just for protein location, but also for protein conformation and biochemical function. Large-scale microscopy-based screening is also being accelerated by a coincident development of machine-based learning that offers a framework for truly unbiased data acquisition and analysis at very large scales. This review will summarize the newest technologies in light, electron, and atomic force microscopy in the context of unique challenges with huntingtin cell biology and biochemistry.

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

Cited by 22 publications

References 135 publications

Structural Basis of Huntingtin Fibril Polymorphism Revealed by Cryogenic Electron Microscopy of Exon 1 HTT Fibrils

Structural Basis of Huntingtin Fibril Polymorphism Revealed by Cryogenic Electron Microscopy of Exon 1 HTT Fibrils

Emerging Therapies for Huntington’s Disease – Focus on N-Terminal Huntingtin and Huntingtin Exon 1

Recent Microscopy Advances and the Applications to Huntington’s Disease Research

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