Hsp90 Inhibition: A Promising Therapeutic Approach for ARSACS.

Area of Science:

• Neurobiology
• Genetics
• Mitochondrial Biology

Background:

• Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a neurodegenerative disease linked to mutations in the SACS gene, affecting the sacsin protein.
• Sacsin is implicated in protein folding and proteostasis, with patient cells showing cytoskeletal disorganization and impaired mitochondrial function.
• Vimentin bundling serves as a biomarker for sacsin function, altered in ARSACS patients and even asymptomatic carriers.

Purpose of the Study:

• To investigate the therapeutic potential of inhibiting Heat Shock Protein 90 (Hsp90) using the compound KU-32 in ARSACS.
• To assess the impact of Hsp90 inhibition on vimentin bundling and mitochondrial function in ARSACS patient-derived cells.

Main Methods:

• Utilized vimentin bundling as a biomarker for sacsin function in ARSACS cells.
• Treated ARSACS patient and carrier cells with KU-32, a C-terminal-domain-targeted Hsp90 inhibitor.
• Assessed mitochondrial membrane potential and electron transport chain function following mitotoxin challenge and KU-32 treatment.

Main Results:

• ARSACS patient cells exhibited significantly increased vimentin bundling, also observed in asymptomatic carriers.
• KU-32 treatment markedly reduced vimentin bundling in both patient and carrier cells.
• Hsp90 inhibition restored mitochondrial membrane potential and electron transport chain function in ARSACS cells challenged with mitotoxins.

Conclusions:

• Targeting the heat-shock response via Hsp90 inhibition shows promise for alleviating key cellular defects in ARSACS.
• KU-32 treatment effectively reduces vimentin bundling and improves mitochondrial function, indicating potential therapeutic benefits for ARSACS.
• These findings highlight Hsp90 inhibition as a potential therapeutic strategy for ARSACS, addressing both cytoskeletal and mitochondrial pathology.