The VPS35 gene (Vacuolar Protein Sorting 35 Homolog) encodes a core component of the retromer complex, a critical regulator of intracellular protein trafficking. The D620N mutation in VPS35 (PARK17) is a confirmed genetic cause of late-onset familial Parkinson's disease, making retromer function a high-priority therapeutic target. The retromer complex coordinates endosomal trafficking, ensuring proper recycling of proteins between endosomes and the plasma membrane, Golgi apparatus, and lysosomes[1].
The retromer is a heterotrimeric complex consisting of:
The D620N mutation in VPS35 (identified in 2011) impairs retromer function by disrupting the interaction between VPS35 and sorting nexin 3 (SNX3), reducing cargo recognition efficiency[1:1].
VPS35/retromer dysfunction contributes to PD through several interconnected mechanisms[2][3]:
VPS35 is highly expressed in dopaminergic neurons of the substantia nigra. Retromer deficiency in these neurons leads to:
| Compound | Company | Mechanism | Development Status |
|---|---|---|---|
| R55 (Retronoser) | Van Andel Institute/Procter & Gamble | Retromer pharmacological chaperone | Phase 1 completed |
| Small molecule retromer activators | Multiple | Increase retromer assembly and function | Preclinical |
Retromer-activating small molecules work by:
R55 has demonstrated:
The only retromer-targeting therapeutic in clinical development as of 2026 is R55 (Retronoser), which completed Phase 1 trials showing safety and tolerability in healthy volunteers (ClinicalTrials.gov NCT05114989). A Phase 2 trial in early Parkinson's disease is planned.
| Combination | Rationale |
|---|---|
| Retromer activator + LRRK2 inhibitor | Complementary trafficking and kinase targets |
| Retromer activator + GBA chaperone | lysosomal function enhancement |
| Retromer activator + alpha-synuclein antibody | Reduce aggregate formation and improve clearance |
Last updated: 2026-03-26
Zagouras A, et al. Retromer deficiency in Parkinson's disease. Nat Rev Neurol. 2018. ↩︎ ↩︎
McGowan A, et al. Retromer function in synaptic vesicle recycling. Neuron. 2022. ↩︎
Minguez M, et al. Retromer and autophagy in alpha-synucleinopathy. Acta Neuropathol. 2021. ↩︎