Dysfunctional Dopamine Packaging Linked to Toxic Processes in Parkinson's, ATP Offers Mitigation
A recent study has identified that dysfunctional packaging of the neurotransmitter dopamine contributes to toxic processes in neurons, which can be mitigated by delivering adenosine triphosphate (ATP).
Parkinson's disease progressively damages dopamine-producing neurons in the midbrain, leading to motor symptoms such as tremors and stiffness. Key characteristics include the accumulation of the α-synuclein protein into Lewy bodies and the loss of dopaminergic neurons. Researchers observed that dopamine oxidizes into toxic substances and causes neuronal damage if not properly packaged in vesicles.
Lena Burbulla, Professor of Metabolic Biochemistry at LMU and lead author of the study published in Science Advances, noted that the cause of this dysfunctional packaging was previously unclear.
Uncovering the Mechanism
Researchers utilized induced pluripotent stem cells (iPSCs) from a Parkinson's patient with a defective DJ-1 gene and genetically modified iPSCs lacking the DJ-1 gene. These cells were converted into neurons for study. The absence of DJ-1 is associated with energy deficiencies observed in various forms of Parkinson's.
Through protein analysis, imaging, and dopamine sensors, the team determined that the VMAT2 protein, responsible for dopamine packaging within vesicles, operates inefficiently in Parkinson's neurons.
This inefficiency results from both a lack of ATP, the cellular energy carrier, and insufficient production of VMAT2. Consequently, dopamine oxidizes and forms toxins.
The Role of α-Synuclein and ATP Intervention
Additionally, misfolded α-synuclein protein accumulates, potentially as a result of oxidized dopamine binding to and promoting protein accumulation. The study demonstrated that the introduction of ATP restored dopamine packaging and halted the damage.
This finding links energy deficiency to dopamine packaging and neuronal vulnerability, proposing a new mechanism for Parkinson's disease.
The researchers suggest that maintaining functional VMAT2 and secure dopamine packaging could protect midbrain neurons and potentially slow disease progression. They also indicated that iPSC-based disease modeling could facilitate future therapy tests in patient cells, potentially accelerating clinical translation.