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.萨利佐林（Salsolinol，化学名1-甲基-6,7-二羟基-1,2,3,4-四氢异喹啉，简称Sal）是一种儿茶酚异喹啉类化合物，因其结构与1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）相似而具有神经毒性——MPTP是一种可引发帕金森病（PD）的环境毒素。然而，Sal介导多巴胺能神经元死亡的具体分子机制仍不明确。本研究发现，Sal可显著升高PC12细胞中mRNA的N6-甲基腺嘌呤（N6-methyladenosine，m6A）整体修饰水平，其主要途径是通过下调m6A去甲基化酶FTO（脂肪量和肥胖相关蛋白，fat mass and obesity-associated protein）与ALKBH5（alkB同源物5，alkB homolog 5）的表达。RNA测序（RNA-Seq）分析结果显示，Sal可通过RNA甲基化调控Hippo信号通路，进而发挥神经毒性作用。研究发现，m6A阅读蛋白YTHDF2（含YTH结构域家族蛋白2，YTH domain-containing family protein 2）可促进携带m6A修饰的YAP1（Yes相关蛋白1，Yes-associated protein 1）mRNA的降解，而YAP1正是Hippo通路的下游关键效应分子。此外，YAP1表达下调还可诱导细胞自噬，这表明YAP1与细胞自噬的相互调控可引发神经毒性。本研究结果揭示了Sal对m6A RNA甲基化的调控作用，并阐明Sal可作为一种RNA修饰诱导剂，通过调控YAP1与细胞自噬介导多巴胺能神经元死亡。该研究为深入理解儿茶酚异喹啉类化合物的神经毒性效应提供了更全面的见解，也可为进一步评估RNA甲基化在帕金森病发病机制中的作用提供参考依据。