Polyglutamine expansion diseases: More than simple repeats.

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Polyglutamine (polyQ) repeat proteins are abundant in humans, but expansions in nine specific proteins cause severe neurodegenerative disorders.
• The length of the polyQ tract is critical, but other protein regions and interactions also influence aggregation and disease onset.

Purpose of the Study:

• To review recent findings on the aggregation pathways of disease-related polyQ proteins.
• To highlight the role of ataxin-3, the protein implicated in Machado-Joseph disease, as a model system.

Main Methods:

• Literature review of recent data on polyglutamine protein aggregation.
• Focus on intrinsic protein features, protein-protein interactions, and post-translational modifications.

Main Results:

• Aggregation is modulated by factors beyond the polyQ tract, including aggregation-prone regions (APRs) and flanking sequences.
• Protein-protein interactions can shield APRs or alter aggregation pathways.
• Post-translational modifications fine-tune polyQ protein self-assembly and cellular processing.

Conclusions:

• Complex aggregation pathways involving multiple factors contribute to polyglutamine diseases.
• Further mechanistic insights into these pathways are essential for therapeutic development.