Identification of salsolinol as an RNA m6A methylation inducer that mediates dopaminergic neuronal death by regulating YAP1 and autophagy
Salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, Sal) is a catechol isoquinoline that can cause neurotoxicity because of its structural similarity with MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), an environmental toxin that causes Parkinson's disease (PD). However, the mechanism by which Sal mediates dopaminergic neuronal death remains unclear. In this study, we found that Sal can significantly enhance the global level of N6-methyladenosine (m6A) mRNA methylation in PC12 cells, mainly by inducing the downregulation of the expression of m6A demethylase FTO (fat mass and obesity-associated protein) and ALKBH5 (alkB homolog 5). The results of the RNA-Seq analysis showed that Sal can exert a neurotoxic effect by regulating the Hippo signaling pathway through RNA methylation. We found that m6A reader YTHDF2 (YTH domain-containing family protein 2) promoted the degradation of m6A-containing YAP1 (Yes-associated protein 1) mRNA, which is a downstream key effector in the Hippo pathway. Additionally, the downregulation of YAP1 can also promote autophagy, indicating that the inter-regulation of YAP1 and autophagy can lead to neurotoxicity. Our findings showed the effect of Sal on m6A RNA methylation and revealed that Sal can act as an RNA modification inducer mediating dopaminergic neuronal death through YAP1 and autophagy. Our results provided greater insights into the neurotoxic effects of catechol isoquinolines and might be used as a reference for further assessing the involvement of RNA methylation in the pathogenesis of PD. Overall design: 200 µM Sal-treated PC12 cells and controls were collected for RNA extraction