Toxicity and infectivity: insights from de novo prion formation

Area of Science:

• Biochemistry
• Cell Biology
• Neuroscience

Background:

• Prions are infectious misfolded proteins linked to neurodegenerative diseases.
• Prion oligomers are thought to be cytotoxic, with genetic factors modulating toxicity.
• The yeast prion [PSI+] model system offers insights into prion formation and toxicity.

Purpose of the Study:

• To investigate the role of the VPS5 gene in yeast prion formation, aggregate assembly, and toxicity.
• To compare prion infectivity and oligomer formation in wild-type and vps5∆ yeast strains.
• To elucidate the cellular mechanisms underlying VPS5-dependent prion toxicity.

Main Methods:

• Utilizing yeast genetics, specifically the [PSI+] prion model.
• Employing SDS-PAGE to assess the formation of SDS-resistant prion oligomers.
• Employing green fluorescent protein (GFP) fusions to visualize and track prion aggregate dynamics in vivo.
• Comparing prion infectivity between wild-type and vps5∆ yeast lysates.

Main Results:

• Newly formed prion oligomers and infectivity were comparable between wild-type and vps5∆ yeast strains.
• vps5∆ strains exhibited altered prion aggregate morphology, characterized by small, mobile foci instead of large, immobile aggregates.
• The cellular milieu in vps5∆ strains may impede the efficient recruitment and sequestration of newly formed prions.

Conclusions:

• VPS5 deletion alters prion aggregate assembly dynamics, leading to a population of small, mobile foci.
• This altered aggregation state in vps5∆ strains may contribute to increased cellular toxicity.
• Changes in the cellular environment due to VPS5 deletion could impair the sequestration of prions, exacerbating toxicity.