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Updated: Sep 6, 2025
Gait Analysis of Age-dependent Motor Impairments in Mice with Neurodegeneration
Published on: June 18, 2018
Mutant VPS35-D620N induces motor dysfunction and impairs DAT-mediated dopamine recycling pathway
Yi Huang1,2, Heng Huang1, Leping Zhou1
1Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University; Guangdong Provincial Key Laboratory of Diagnosis and Treatment of Major Neurological Diseases; National Key Clinical Department and Key Discipline of Neurology, Guangzhou 510080, China.
Abstract:
The D620N mutation in vacuolar protein sorting protein 35 (VPS35) gene has been identified to be linked to late onset familial Parkinson disease (PD). However, the pathophysiological roles of VPS35-D620N in PD remain unclear. Here, we generated the transgenic Caenorhabditis elegans overexpressing either human wild type or PD-linked mutant VPS35-D620N in neurons. C. elegans expressing VPS35-D620N, compared with non-transgenic controls, showed movement disorders and dopaminergic neuron loss. VPS35-D620N worms displayed more swimming induced paralysis but showed no defects in BSR assays, thus indicating the disruption of dopamine (DA) recycling back inside neurons. Moreover, VPS35 formed a protein interaction complex with DA transporter (DAT), RAB5, RAB11 and FAM21. In contrast, the VPS35-D620N mutant destabilized these interactions, thus disrupting DAT transport from early endosomes to recycling endosomes, and decreasing DAT at the cell surface. These effects together increased DA in synaptic clefts, and led to dopaminergic neuron degeneration and motor dysfunction. Treatment with reserpine significantly decreased the swimming induced paralysis in VPS35-D620N worms, as compared with vehicle treated VPS35-D620N worms. Our studies not only provide novel insights into the mechanisms of VPS35-D620N-induced dopaminergic neuron degeneration and motor dysfunction via disruption of DAT function and the DA signaling pathway but also indicate a potential strategy to treat VPS35-D620N-related PD and other disorders.
Insights
The VPS35-D620N mutation causes Parkinson disease by disrupting dopamine recycling and transporter function, leading to neuron loss and motor deficits. Reserpine treatment showed potential therapeutic benefits.
Area of Science:
- Neuroscience
- Genetics
- Molecular Biology
Background:
- Late-onset familial Parkinson disease (PD) is linked to the D620N mutation in the vacuolar protein sorting protein 35 (VPS35) gene.
- The precise pathophysiological mechanisms of VPS35-D620N in PD pathogenesis remain largely unknown.
Purpose of the Study:
- To investigate the role of the PD-linked VPS35-D620N mutation in neuronal dysfunction and motor deficits.
- To elucidate the molecular mechanisms underlying VPS35-D620N-induced neurodegeneration, focusing on dopamine (DA) homeostasis and transport.
Main Methods:
- Generation of transgenic Caenorhabditis elegans (C. elegans) models overexpressing wild-type or mutant human VPS35-D620N in neurons.
- Assessment of motor function, dopaminergic neuron integrity, and dopamine recycling.
- Analysis of VPS35 protein interactions with dopamine transporter (DAT) and endosomal trafficking proteins (RAB5, RAB11, FAM21).
- Pharmacological evaluation of reserpine treatment on motor phenotypes.
Main Results:
- C. elegans expressing VPS35-D620N exhibited significant movement disorders and loss of dopaminergic neurons.
- VPS35-D620N disrupted the interaction with DAT and endosomal trafficking proteins, impairing DAT surface expression and DA recycling.
- Increased extracellular DA levels and subsequent dopaminergic neuron degeneration were observed.
- Reserpine treatment ameliorated the swimming-induced paralysis in VPS35-D620N worms.
Conclusions:
- The VPS35-D620N mutation impairs dopaminergic neuron function and survival by disrupting DAT trafficking and dopamine signaling pathways.
- These findings provide critical insights into PD mechanisms and suggest potential therapeutic strategies targeting DAT function for VPS35-related PD.
