Vesicular Monoamine Transport Mechanisms in Neurodegenerative Disorders

The sequestration of monoamine neurotransmitters—principally dopamine, serotonin and noradrenaline—into synaptic vesicles is mediated by vesicular monoamine transporters (VMATs). These membrane proteins harness the proton electrochemical gradient across vesicle membranes to exchange two protons for one cytosolic monoamine, thereby preserving neurotransmitter pools and limiting cytosolic toxicity. In the central nervous system, VMAT2 predominates in dopaminergic, serotonergic and noradrenergic nerve terminals, and its dysfunction has been implicated in the pathogenesis of Parkinson’s disease, Lewy body dementia and related disorders. Impaired vesicular loading leads to elevated cytosolic monoamine concentrations, oxidative stress and protein misfolding, driving selective neuronal vulnerability. Moreover, interplay between VMAT2 and enzymes of monoamine synthesis ensures tight coupling of production and packaging, while protein–protein interactions and post-translational modifications modulate transporter turnover. Therapeutic modulation of VMAT2 activity thus represents a dual strategy: restoring vesicular storage to counteract neurodegenerative cascades and refining monoamine homeostasis in clinical syndromes characterised by dysregulated neurotransmission.

Research from Nature Portfolio

High-resolution structural analysis of VMAT2 variants engineered for cryo-EM has revealed unexpected folding plasticity within the major facilitator superfamily fold. In one study, a frog orthologue adopted the canonical architecture, while a stabilised mammalian construct exhibited a non-canonical arrangement. Comparative docking and transport assays delineated substrate-binding sites and revealed conformational transitions underlying proton-driven exchange. These insights refine current models of monoamine recognition and provide a template for design of selective modulators that may one day ameliorate transporter-linked neurodegeneration.

Vesicular Monoamine Transport Mechanisms in Neurodegenerative Disorders publication trend

The graph below shows the total number of articles in vesicular monoamine transport mechanisms in neurodegenerative disorders across all publications each year (not limited to Nature Index journals).

Technical terms

Vesicular monoamine transporter 2 (VMAT2): A proton-driven antiporter that packages monoamine neurotransmitters into synaptic vesicles for regulated release.

Major facilitator superfamily (MFS): A large group of secondary transport proteins that share a common fold and use electrochemical gradients to move substrates across membranes.

Synaptic vesicle: A membrane-bound organelle in presynaptic terminals that stores neurotransmitters prior to exocytotic release.

Proton electrochemical gradient: The combined difference in proton concentration and electrical potential across a membrane, which provides the driving force for secondary active transporters.

References

1. Transport and inhibition mechanism for VMAT2-mediated synaptic vesicle loading of monoamines. Cell Research (2024).
2. Engineering of a mammalian VMAT2 for cryo-EM analysis results in non-canonical protein folding. Nature Communications (2024).
3. Dopamine and vesicular monoamine transport loss supports incidental Lewy body disease as preclinical idiopathic Parkinson. npj Parkinson's Disease (2023).
4. Tricyclic and tetracyclic antidepressants upregulate VMAT2 activity and rescue disease-causing VMAT2 variants. Neuropsychopharmacology (2024).
5. A Biochemical and Functional Protein Complex Involving Dopamine Synthesis and Transport into Synaptic Vesicles. Journal of Biological Chemistry (2009).