Putting huntingtin "aggregation" in view with windows into the cellular milieu

Area of Science:

• Neuroscience
• Genetics
• Molecular Biology

Background:

• Huntington's disease (HD) is caused by CAG repeat expansions in the Huntingtin (Htt) gene.
• Expanded polyglutamine (polyQ) sequences in Htt lead to protein aggregation and inclusion body formation in neurons.
• Despite the genetic cause being known for nearly 20 years, the precise relationship between Htt aggregation and HD pathogenesis remains unclear.

Purpose of the Study:

• To review the current understanding of Huntingtin (Htt) protein aggregation in Huntington's disease (HD).
• To clarify the molecular mechanisms underlying polyglutamine (polyQ) Htt aggregation and its cellular consequences.
• To discuss challenges and propose future strategies for investigating Htt aggregation in relation to cellular dysfunction in HD.

Main Methods:

• Literature review of historical and current research on Htt aggregation.
• Analysis of the intrinsic properties of polyQ-expanded Htt that promote aggregation.
• Discussion of the complexities and potential ambiguities in defining "aggregation" in the context of HD.

Main Results:

• Htt aggregation is a hallmark of Huntington's disease, with aggregation propensity correlating with polyQ length.
• The term "aggregation" encompasses diverse processes with potentially opposing effects on cellular health.
• Current knowledge linking Htt aggregation to specific disease mechanisms is fragmented and debated.

Conclusions:

• Further research is needed to precisely define the molecular events of Htt aggregation.
• Clarifying the distinct processes within "aggregation" is essential for understanding their impact on cellular dysfunction.
• Improved understanding of Htt aggregation mechanisms will guide the development of targeted therapies for Huntington's disease.