Mitochondrial dysfunction and mitophagy defect triggered by heterozygous GBA mutations.

Area of Science:

• Neuroscience
• Genetics
• Cell Biology

Background:

• Heterozygous mutations in the GBA gene are the most common genetic risk factor for Parkinson disease (PD).
• The precise mechanisms linking GBA mutations to PD pathogenesis remain unclear.
• Mitochondrial dysfunction is a key feature of Parkinson disease.

Purpose of the Study:

• To investigate the mechanistic link between heterozygous GBA mutations and mitochondrial dysfunction in Parkinson disease.
• To elucidate the role of GBA in mitophagy, the selective removal of damaged mitochondria via autophagy.
• To explore how GBA mutations affect autophagy and mitochondrial quality control.

Main Methods:

• Utilized Gba^L444P/WT knockin mice and SHSY-5Y neuroblastoma cells to model heterozygous GBA mutations.
• Assessed mitochondrial function, autophagy induction, and mitophagy processes using cellular and molecular assays.
• Analyzed postmortem brain tissue from Parkinson disease patients with and without GBA mutations.

Main Results:

• In Gba^L444P/WT mice and cell models, the L444P GBA mutation inhibited mitophagy by impairing mitochondrial priming and autophagy.
• Genetic depletion of GBA impaired the lysosomal clearance of autophagic cargo.
• Parkinson disease patients with heterozygous GBA mutations exhibited increased mitochondrial content, oxidative stress, and impaired autophagy in brain tissue.

Conclusions:

• Heterozygous GBA mutations mechanistically link to Parkinson disease through the impairment of mitophagy.
• Disruption of mitochondrial quality control via impaired mitophagy provides a basis for GBA-associated Parkinson disease.
• These findings highlight GBA's critical role in maintaining mitochondrial homeostasis and suggest therapeutic targets for GBA-PD.