Immunoproteasome-specific Subunit Alterations as a Potential Therapeutic Target for Mitochondriopathies

Area of Science:

• Cell Biology
• Biochemistry
• Genetics

Background:

• Mitochondria are vital organelles for ATP production via oxidative phosphorylation (OXPHOS).
• Nuclear-encoded mitochondrial proteins are synthesized in the cytosol and imported into mitochondria.
• The proteasome degrades inefficiently imported mitochondrial proteins, ensuring quality control.

Purpose of the Study:

• To investigate the role of immunoproteasome in mitochondrial protein import.
• To evaluate immunoproteasome inhibitors as a therapeutic strategy for mitochondriopathies.

Main Methods:

• Utilized patient-derived fibroblasts with impaired mitochondrial protein import.
• Administered immunoproteasome-specific inhibitors and bortezomib.
• Assessed protein abundance of respiratory complex IV and cellular toxicity.

Main Results:

• Targeting immunoproteasome inhibited degradation and restored inefficiently imported respiratory complex IV proteins.
• Immunoproteasome inhibitors demonstrated decreased toxicity compared to bortezomib.
• Mitochondrial dysfunction induces immunoproteasome subunit (e.g., PSMB9) incorporation.

Conclusions:

• Immunoproteasome subunits represent a novel therapeutic target for mitochondriopathies.
• Immunoproteasome inhibition offers a potentially safer alternative to current proteasome inhibitors for treating these conditions.