Hyperglycemia is a representative hallmark and risk factor for diabetes mellitus (DM) and is closely linked to DM‐associated neuronal cell death. Previous investigators reported on a genome‐wide association study and showed relationships between DM and melatonin receptor (MT), highlighting the role of MT signaling by assessing melatonin in DM. However, the role of MT signaling in DM pathogenesis is unclear. Therefore, we investigated the role of mitophagy regulators in high glucose‐induced neuronal cell death and the effect of melatonin against high glucose‐induced mitophagy regulators in neuronal cells. In our results, high glucose significantly increased PTEN‐induced putative kinase 1 (PINK1) and LC‐3B expressions; as well it decreased cytochrome c oxidase subunit 4 expression and Mitotracker™ fluorescence intensity. Silencing of PINK1 induced mitochondrial reactive oxygen species (ROS) accumulation and mitochondrial membrane potential impairment, increased expressions of cleaved caspases, and increased the number of annexin V‐positive cells. In addition, high glucose‐stimulated melatonin receptor 1B (MTNR1B) mRNA and PINK1 expressions were reversed by ROS scavenger N‐acetyl cysteine pretreatment. Upregulation of PINK1 expression in neuronal cells is suppressed by pretreatment with MT₂ receptor‐specific inhibitor 4‐P‐PDOT. We further showed melatonin stimulated Akt phosphorylation, which was followed by nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB) phosphorylation and nuclear translocation. Silencing of PINK1 expression abolished melatonin‐regulated mitochondrial ROS production, cleaved caspase‐3 and caspase‐9 expressions, and the number of annexin V‐positive cells. In conclusion, we have demonstrated the melatonin stimulates PINK1 expression via an MT₂/Akt/NF‐κB pathway, and such stimulation is important for the prevention of neuronal cell apoptosis under high glucose conditions.

中文翻译：

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褪黑素增强高糖诱导的PINK1表达可刺激神经元细胞存活：涉及MT2 / Akt /NF-κB途径

高血糖是糖尿病（DM）的代表标志和危险因素，并且与DM相关的神经元细胞死亡密切相关。先前的研究人员在全基因组关联研究中进行了报道，并显示了DM与褪黑激素受体（MT）之间的关系，并通过评估DM中的褪黑激素来突出MT信号的作用。然而，尚不清楚MT信号在DM发病机理中的作用。因此，我们研究了线粒体调节剂在高糖诱导的神经元细胞死亡中的作用以及褪黑素对高糖诱导的神经元细胞中的线粒体调节剂的作用。在我们的结果中，高葡萄糖显着增加了PTEN诱导的假定激酶1（PINK1）和LC-3B的表达；同时降低了细胞色素C氧化酶亚基4的表达和Mitotracker™荧光强度。PINK1沉默导致线粒体活性氧（ROS）积累和线粒体膜电位受损，裂解的胱天蛋白酶表达增加，膜联蛋白V阳性细胞数量增加。此外，高葡萄糖刺激的褪黑激素受体1B（ROS清道夫N-乙酰半胱氨酸预处理可逆转MTNR1B）mRNA和PINK1的表达。MT ₂受体特异性抑制剂4-P-PDOT预处理可抑制神经元细胞中PINK1表达的上调。我们进一步显示了褪黑激素刺激的Akt磷酸化，然后是活化B细胞的核因子κ轻链增强子（NF-κB）磷酸化和核易位。PINK1表达的沉默消除了褪黑素调节的线粒体ROS的产生，裂解了caspase-3和caspase-9的表达以及膜联蛋白V阳性细胞的数量。总之，我们已经证明了褪黑激素通过MT ₂刺激PINK1表达/ Akt /NF-κB途径，这种刺激对于预防高糖条件下神经元细胞的凋亡非常重要。