Topical Area: Maternal, Perinatal and Pediatric Nutrition
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.
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.
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)