VPS35 Deficiency or Mutation Causes Dopaminergic Neuronal Loss by Impairing Mitochondrial Fusion and Function

Area of Science:

• Neuroscience
• Cell Biology
• Genetics

Background:

• Vacuolar protein sorting-35 (VPS35) is crucial for endosomal trafficking and linked to familial Parkinson's disease (PD).
• Dopaminergic neuron dysfunction is central to PD pathogenesis.
• Mitochondrial integrity is vital for neuronal health.

Purpose of the Study:

• To investigate the role of VPS35 in dopamine (DA) neuron function and PD.
• To elucidate the cellular mechanisms underlying VPS35-associated PD.
• To explore the connection between VPS35, mitochondria, and PD.

Main Methods:

• Generated a specific VPS35 gene deletion in DA neurons in a model system.
• Assessed PD-like deficits, including DA neuron loss and α-synuclein aggregation.
• Analyzed mitochondrial morphology and function.
• Investigated the role of mitochondrial E3 ubiquitin ligase 1 (MUL1) and mitofusin 2 (MFN2).

Main Results:

• VPS35 deletion in DA neurons induced PD-like deficits and α-synuclein accumulation.
• Mitochondria in VPS35-deficient DA neurons showed fragmentation and dysfunction, reversible by wild-type VPS35.
• VPS35 deficiency increased MUL1, causing MFN2 degradation and mitochondrial fragmentation.
• MUL1 suppression partially rescued MFN2 reduction and DA neuron loss, but not α-synuclein accumulation.

Conclusions:

• VPS35 dysfunction in DA neurons directly contributes to PD pathogenesis.
• VPS35 deficiency impairs mitochondrial function via MUL1-mediated MFN2 degradation.
• This study reveals a cellular mechanism linking VPS35 to mitochondrial impairment in Parkinson's disease.