Hypoxia rescues complex 1-associated disease caused by proteostatic defects

Area of Science:

• Mitochondrial biology
• Neuroscience
• Proteostasis and disease

Background:

• Mitochondrial proteostasis impairment is implicated in numerous diseases, with limited therapeutic options.
• HTRA2, a mitochondrial protease, plays a crucial role in maintaining mitochondrial health.

Purpose of the Study:

• To investigate the therapeutic potential of hypoxia in rescuing mitochondrial dysfunction and neurodegeneration caused by HTRA2 deficiency.
• To elucidate the molecular mechanisms linking HTRA2, CLPB, and Complex I function.

Main Methods:

• Utilized an Htra2 mutant mouse model exhibiting neurodegeneration.
• Administered continuous hypoxia therapy to the mutant mice.
• Investigated protein complex formation and mitochondrial function through biochemical assays.

Main Results:

• Continuous hypoxia significantly rescued striatal degeneration and extended lifespan in Htra2 mutant mice.
• HTRA2 was found to form a functional complex with the disaggregase CLPB.
• Loss of HTRA2 or CLPB led to aggregation of Complex I subunits, causing secondary Complex I dysfunction and impaired oxygen consumption.

Conclusions:

• Hypoxia therapy can effectively rescue neurodegeneration and extend lifespan in a model of mitochondrial proteostasis disease.
• A novel proteostasis pathway involving HTRA2, CLPB, and Complex I quality control was identified.
• These findings suggest hypoxia therapy may be beneficial for diseases involving secondary Complex I dysfunction.