Inositol Deficiency Induces Autophagy Impairing via PI3K/Akt/mTOR/p70S6K Signaling (P11-032-19)

Abstract

Abstract Objectives Our previous case-control study found that maternal MI deficiency was associated with an increased risk of NTDs. Bioinformatics analysis showed that PI3K/Akt/mTOR/p70S6K signaling pathway might be one of the important regulatory mechanisms of inositol deficiency-induced NTDs. So, we intended to explore the possible mechanisms of PI3K/Akt/mTOR/p70S6K signaling in inositol deficiency-induced neural tube defects (NTDs) in this study. Methods The activity of the PI3-kinase in MI deficiency NE-4C cells was detected by the PI3-kinase ELISA kit. Using the method of western blot, we analyzed the activity of the PI3K/Akt/mTore/p70S6K signaling pathway and the level of LC3B. And the LC3B levels were also detected by electron microscopy. Results The result showed that PI3K activity was significantly higher in the Li2CO3-treated group than in the control cells (P < 0.05), and the increased kinase activity was abolished by additional treatment with MI (P < 0.05). We found that PI3K activity decreased dramatically with the increasing MI concentration in a dose-dependent manner when the inositol concentration was below 5 mg/L in vitro enzymology experiment. The result showed that the PI3K/Akt/mTOR/p70S6K signaling pathway significant activated in MI deficient NE-4C cells compare with the controls. We found that the autophagy was significantly impaired by Li2CO3 treatment in NE-4C cells, and the effects were abrogated by combining Li2CO3 with MI or signaling inhibitor (Ly294002 and Rapamycin). Which suggested that MI deficiency induced autophagy impairment through the Akt/mTOR/p70S6K signaling. We next validate the above result in our previous established MI deficiency mouse model and found PI3K activity was significantly elevated in heart, neural and placenta tissues 8 hours after Li2CO3 injection. The maternal serum MI levels correlated with the PI3K activity in the mouse embryonic neural tissue (R = –0.817, P < 0.05). And the activity of Akt/mTOR/p70S6K signaling was over activated accompanied by the reduced level of LC3B. Conclusions These results showed that inositol deficiency activated PI3K/Akt/mTOR/p70S6K signaling, thus causing impaired autophagy. Funding Sources This study was supported by The National Key Basic Research Program(2018YFC1002500), National Nature Science Foundation of China (81571443 to JW, 81801451 to JG).