Related Experiment Video
Updated: Aug 14, 2026
Whole-brain Segmentation and Change-point Analysis of Anatomical Brain MRI—Application in Premanifest Huntington's Disease
Published on: June 9, 2018
Aggregation in Huntington's disease: insights through modelling
Branka Cajavec1, Samuel Bernard, Hanspeter Herzel
1Institute for Theoretical Biology, Humboldt University, Invalidenstrasse 43, 10115 Berlin, Germany. b.cajavec@biologie.hu-berlin.de
Insights
Huntington's Disease (HD) involves mutant huntingtin protein cleavage by caspase-2. Mathematical modeling suggests toxic oligomers, not aggregates, cause neuronal death, independent of caspase activity.
Area of Science:
- Neuroscience
- Biochemistry
- Mathematical Biology
Background:
- Huntington's Disease (HD) is a neurodegenerative disorder caused by polyglutamine expansion in huntingtin (Htt).
- Mutant Htt is cleaved by caspases, releasing toxic fragments implicated in neuronal death.
- The role of Htt aggregation in HD pathogenesis remains debated, with some evidence pointing to soluble oligomers as the primary toxic species.
Purpose of the Study:
- To develop a mathematical model of mutant huntingtin aggregation in HD.
- To investigate the relationship between caspase-2 activity, Htt fragment release, aggregation dynamics, and neuronal death.
- To explore the role of polyglutamine length in HD onset and disease progression.
Main Methods:
- Mathematical modeling of caspase-2 dynamics and Htt fragment aggregation.
- Simulation of monomeric Htt fragment release and subsequent aggregation through intermediate steps.
- Analysis of the model's predictions regarding toxic oligomer concentration and its dependence on caspase activity and polyglutamine length.
Main Results:
- The mathematical model describes the dynamic behavior of caspase-2 and the aggregation process of Htt fragments.
- Model predictions indicate that toxic, intermediate oligomeric structures do not increase with elevated caspase activity.
- The concentration of toxic oligomers is independent of caspase-2 activity.
Conclusions:
- The study suggests that intermediate oligomeric forms of toxic Htt fragments do not drive selective and polyglutamine-dependent neuronal death in HD.
- Findings challenge the direct link between increased caspase activity and the accumulation of toxic oligomers.
- Further research is needed to elucidate the precise mechanisms underlying HD pathogenesis and neuronal cell loss.
Abstract:
Huntington's Disease (HD) is a late-onset, progressively degenerative brain disorder characterized by cell loss in the striatum and cortex. HD is caused by a polyglutamine (polyQ) expansion in the protein huntingtin (Htt). The mutant Htt is a substrate for caspases -2, -3 and -6. The cleavage of mutant Htt by caspase-2 has been suggested to underlie the selective neuronal death in HD. Once the mutant Htt is cleaved, a sticky and toxic fragment with the potential to form aggregates is released. The role of aggregation in the progression of HD has been extensively studied, yielding a plethora of ambivalent results. It has been shown that these are the diffuse, monomeric and oligomeric, forms of the mutant Htt fragment rather than the aggregates that are the major source of toxicity to the cells. We present here a mathematical model for aggregation in HD and discuss how it can relate to the selective neuronal death and the dependence of the disease onset on polyQ length. We describe the dynamical behavior of caspase-2, the release of monomeric forms of the mutant Htt fragment and the aggregation of these fragments through intermediate steps. Our model predicts that the concentration of toxic, intermediate oligomeric structures does not increase with increased caspase activity. We therefore suggest that the intermediate oligomeric forms of toxic Htt fragment do not account for selective and polyQ dependent neuronal death.
