Oligomeric and polymeric aggregates formed by proteins containing expanded polyglutamine

Area of Science:

• Neuroscience
• Biochemistry
• Protein Chemistry

Background:

• Expanded polyglutamine (polyQ) proteins cause neurodegenerative diseases.
• These diseases are linked to insoluble neuronal inclusions and cell death.

Purpose of the Study:

• To characterize the aggregates formed by expanded polyQ proteins.
• To investigate the stability and solubility of these aggregates.

Main Methods:

• Treatment of polyQ aggregates with concentrated formic acid.
• Analysis of soluble and insoluble fractions using gel electrophoresis and filtration.

Main Results:

• Expanded polyQ aggregates are resistant to formic acid, indicating unusual stability.
• A formic acid-resistant oligomer is found in Huntington's disease cerebral cortex but not cerebellum.
• Polymeric aggregates in cortical nuclei are insoluble in formic acid and resist gel electrophoresis.

Conclusions:

• Formic acid resistance suggests covalent bonds stabilize polyQ aggregates.
• Aggregate polymerization is more advanced in the cerebral cortex than in cultured cells.
• These findings offer insights into the molecular mechanisms of polyQ diseases.