The Role Of MRNA M6A Modification In The Pathogenesis Of Parkinson’s Disease

Epigenetics is the important biological phenomenon of eukaryotes when the expression or function of a gene can change without altering the sequence of DNA.Up until now,there are many well-known epigenetic modifications in different molecular level,in which RNA epigenetic modification is one of the hottest fields of research in recent years.6-methyladenine（m6A）is the most widely studied chemical modification on mRNA,which is important for the splicing,transport,translation and stability of mRNA.m6A modification is mainly regulated by the methyltransferase（METTL3）and the demethylases（FTO,ALKBH5）.The dynamic balance of this reversible process will affect cell development and the occurrence of a variety of diseases.Parkinson’s disease（PD）is a common neurodegenerative disease,with the degeneration of dopaminergic neurons in the substantia nigra of midbrain.Studies have shown that the occurrence of PD is closely related to epigenetic modification,such as DNA methylation and the acetylation of histone,however,there is no relevant report on the correlation between PD and RNA methylation.Therefore,we try to explore the correlation between RNA methylation and the death of dopaminergic neurons,andreveal its molecular mechanism.Firstly,the cell model and rat model of PD were constructed by neurotoxin6-hydroxydopamine（6-OHDA）,and the changes of RNA methylation in the pathogenesis of PD were investigated.The results showed that a significant decrease of m6A modification in PD cell and rat models,while the expression of demethylase FTO increased significantly,indicated that RNA has been demethylated obviously.Secondly,we constructed a dopaminergic neuronal cell line which overexpressed FTO stably through the lentivirus,and this cell line could be used to explore the effect of low methylation level on the growth of neural cells.The results showed that the overexpressed FTO improve the expression of GRIN1 which related to dopamine neural pathway,leading the increase of Ca²⁺influx in neuron cells.At the same time,overexpressed FTO could also induce oxidative stress,mitochondrial dysfunction and ultimately lead to neuronal apoptosis.Finally,in order to verify that the neuron damage caused by the overexpressed FTO is mediated by its demethylation function,we further used the m6A inhibitor（cycloleucine）to treat dopaminergic neurons.The results are consistent with the apoptosis induced by the overexpressed FTO.Through this study,our research first determined the reduction of RNA methylation in PD models,and further verified that the hypomethylated RNA modification aggravated the damage of neuronal cells.The mechanism of this damage is also discussed:FTO will reduce the m6A modification in mRNA,thereby promoting the expression of GRIN1 protein,resulting in the overload of intracellular Ca²⁺,the increase of oxidative stress and the impairment of mitochondrial function,all of which promote neuronal apoptosis ultimately.The study is expected to provide a new sight to reveal pathogenesis of PD based on RNA epigenetic modification.