Moderate mammalian target of rapamycin inhibition induces autophagy in HTR8/SVneo cells via O‐linked β‐N‐acetylglucosamine signaling

作者：Qiuxia Zhang, Quan Na, Weiwei Song · 发表于：Journal of obstetrics and gynaecology research · 年份：2017 · DOI：10.1111/jog.13410 · 被引用次数：12 · 研究领域：Autophagy in Disease and Therapy、Glycosylation and Glycoproteins Research、Cancer, Hypoxia, and Metabolism

AIM: Autophagy, a highly regulated process with a dual role (pro-survival or pro-death), has been implicated in adverse pregnancy outcomes. The aim of this study was to explore the mechanism whereby mammalian target of rapamycin (mTOR) signaling regulates autophagy by modulating protein O-GlcNAcylation in human trophoblasts. METHODS: HTR8/SVneo cells were incubated in serum-free medium for different time intervals or treated with varying doses of Torin1. Protein expression and cell apoptosis were detected by immunoblotting and flow cytometry, respectively. RESULTS: Short-term serum starvation or slight suppression of mTOR signaling promoted autophagy and decreased apoptosis in HTR8/SVneo cells. Conversely, prolonged serum starvation or excessive inhibition of mTOR reduced autophagy and enhanced cell apoptosis. Both serum starvation and mTOR signaling suppression reduced protein O-GlcNAcylation. Upregulation and downregulation of O-linked β-N-acetylglucosamine (O-GlcNAc) levels attenuated and augmented autophagy, respectively. Moderate mTOR inhibition-induced autophagy was blocked by upregulation of protein O-GlcNAcylation. Furthermore, immunoprecipitation studies revealed that Beclin1 and synaptosome associated protein 29 (SNAP29) could be O-GlcNAcylated, and that slight mTOR inhibition resulted in decreased O-GlcNAc modification of Beclin1 and SNAP29. Notably, we observed an inverse correlation between phosphorylation (Ser15) and O-GlcNAcylation of Beclin1. CONCLUSION: mTOR ...