Periodic Reporting for period 1 - PARTHECOM (New pathway and small-molecule compounds for Parkinson’s disease therapy)
Período documentado: 2023-09-01 hasta 2025-11-30
Parkinson’s disease (PD) is a neurodegenerative disorder which affects more than 10 million people around the world. It is characterised by gradual degeneration and loss of nigrostriatal dopamine (DA) neurons. This results in motor symptoms like rigidity and tremors but also non-motor symptoms like constipation, depression etc. The is no cure for this disease, only alleviation of symptoms is possible. Although experimental administration of neurotrophic factors has shown some promise, they need to be delivered directly into the brain, making the procedure risky and expensive. Importantly, delivery into the brain will not affect non-motor symptoms. Thus, there is a need for drugs that could be delivered systemically and that would cross the blood-brain barrier. Although the aetiology of PD is unknown, certain toxins and mutations are known to contribute. In addition, recent evidence points to a decrease in the methylation of mRNA at adenosine position N6 (m6A). This reversible modification, which is catalysed by methyltransferase like 3 (METTL3), is enriched in neurons and cancer cells affecting the stability, transport and translation of mRNAs.
Our collaborators have developed novel compounds that activate METTL3 and thereby increase cellular m6A levels on mRNA (m6A enhancers). Preliminary testing of these compounds indicated their neuroprotective properties on DA neurons. The main aim of this project was to solidify the importance of mRNA m6A in DA neuron survival. Further, the mechanism of action of how increasing m6A protects neurons was investigated. Finally, the ability of the compounds to penetrate the blood-brain barrier was evaluated. These experiments uncover a completely new pathway for DA neuron protection and pave way for novel therapeutic avenues against PD.
Our collaborators have developed novel compounds that activate METTL3 and thereby increase cellular m6A levels on mRNA (m6A enhancers). Preliminary testing of these compounds indicated their neuroprotective properties on DA neurons. The main aim of this project was to solidify the importance of mRNA m6A in DA neuron survival. Further, the mechanism of action of how increasing m6A protects neurons was investigated. Finally, the ability of the compounds to penetrate the blood-brain barrier was evaluated. These experiments uncover a completely new pathway for DA neuron protection and pave way for novel therapeutic avenues against PD.
To solidify the importance of mRNA m6A in neurons, we aimed to test the effect of m6A enhancers in different paradigms. We established that the m6A enhancers support the viability of mouse DA neurons in 6-hydroxydopamine (6-OHDA) toxicity assay in culture. Conversely, reduction of m6A levels by a METTL3 inhibitor resulted in dose-dependent cell death. To increase the translational aspects of our findings, we next tested our compounds on human induced pluripotent stem cell derived DA neurons. By using these commercially available human DA neurons we established that the m6A enhancers support the viability of these cells and also increase neurite outgrowth. To clarify the mechanism of action of m6A enhancers, we planned to analyse the m6A status of mRNAs by m6A mRNA immunoprecipitation and sequencing. However, considering that m6A influences mRNA stability but also its translation and that proteins are the actual workhorses in the cells, we performed proteomics analyses on neurons treated with METTL3 activator and inhibitor. These experiments revealed the proteins and pathways that are influenced by the m6A modification on mRNA. In addition, we determined the properties of m6A enhancers. Specifically, we determined that these compounds penetrate the blood-brain barrier indicating that these compounds could be administered systemically.
The results of this project demonstrate that increasing mRNA m6A levels by small molecule compounds supports the viability of mouse and human DA neurons in culture. Importantly, this compound also protects DA neurons in vivo in a rat PD model. We uncovered the mechanism of action, how increasing mRNA m6A levels supports neuronal survival. Moreover, we established that these compounds can cross the blood-brain barrier. Collectively, these data demonstrate, for the first time, that increasing mRNA m6A levels can be a new therapeutic avenue for combating PD. Importantly, our compounds show promise for systemic delivery, enabling to influence also non-motor symptoms.