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Updated: Jun 14, 2025
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Generation of Native, Untagged Huntingtin Exon1 Monomer and Fibrils Using a SUMO Fusion Strategy
Published on: June 27, 2018
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Direct Observation of Secondary Nucleation in Huntingtin Amyloid Formation by High-Speed Atomic Force Microscopy
Chris van Ewijk1, Greeshma Jain2, Yari K Knelissen1
1Molecular Biophysics, Zernike Instituut, Rijksuniversiteit Groningen, 9747 AG Groningen, The Netherlands.
Journal of the American Chemical Society
|June 12, 2025
Summary
Researchers observed amyloid fibril formation in Huntington's disease using high-speed atomic force microscopy. They detailed secondary nucleation and elongation processes, finding flanking segments influence primary nucleation but not secondary nucleation.
Area of Science:
- Neuroscience
- Biochemistry
- Structural Biology
Background:
- Amyloid fibril formation is central to neurodegenerative diseases like Huntington's (HD), Alzheimer's, and Parkinson's.
- Protein aggregation involves nucleation, growth, and elongation; secondary nucleation is increasingly recognized as a dominant pathway.
- Understanding these pathways is crucial for developing therapeutics targeting pathogenic protein misfolding.
Purpose of the Study:
- To investigate the mechanistic and structural aspects of secondary nucleation in huntingtin Exon 1 (HttEx1) aggregation, a key process in HD.
- To directly visualize and characterize amyloid formation dynamics, including secondary nucleation and fibril elongation, in real time.
- To elucidate the role of HttEx1 flanking segments in modulating aggregation pathways.
Main Methods:
- High-speed atomic force microscopy (HS-AFM) was employed for real-time, single-particle observation of HttEx1 aggregation.
- Mechanistic and structural studies were conducted to analyze the aggregation process.
- The influence of HttEx1 flanking segments on primary and secondary nucleation was examined.
Main Results:
- HS-AFM revealed dynamic features of HttEx1 amyloid formation, including secondary nucleation, elongation, and nucleated branching leading to fibril bundles.
- The N-terminal HttNT segment was found to enhance primary nucleation but did not influence secondary nucleation.
- Direct visualization provided unprecedented insights into the real-time kinetics of amyloid aggregation.
Conclusions:
- The study illuminates the complex aggregation pathway of HttEx1, highlighting the distinct roles of primary and secondary nucleation.
- Findings emphasize the importance of secondary nucleation in HttEx1 aggregation, relevant to Huntington's disease pathogenesis.
- Understanding these aggregation dynamics offers potential targets for therapeutic interventions aimed at inhibiting or modulating protein misfolding in HD.
