Down-Regulation of Inpp5e Associated With Abnormal Ciliogenesis During Embryonic Neurodevelopment Under Inositol Deficiency.

The inositol polyphosphate-5-phosphatase E (Inpp5e) gene is located on chromosome 9q34.3. The enzyme it encodes mainly hydrolyzes the 5-phosphate groups of phosphatidylinositol (3,4,5)-trisphosphate (PtdIns (3,4,5) P3) and phosphatidylinositol (4,5)-bisphosphate (PtdIns (4,5)P2), which are closely related to ciliogenesis and embryonic neurodevelopment, through mechanisms that are largely unknown. Here we studied the role of Inpp5e gene in ciliogenesis during embryonic neurodevelopment using inositol-deficiency neural tube defects (NTDs) mouse and cell models. Confocal microscopy and scanning electron microscope were used to examine the number and the length of primary cilia. The dynamic changes of Inpp5e expression in embryonic murine brain tissues were observed during Embryonic Day 10.5-13.5 (E 10.5-13.5). Immunohistochemistry, western blot, polymerase chain reaction (PCR) arrays were applied to detect the expression of Inpp5e and cilia-related genes of the embryonic brain tissues in inositol deficiency NTDs mouse. Real-time quantitative PCR (RT-qPCR) was used to validate the candidate genes in cell models. The levels of inositol and PtdIns(3,4) P2 were measured using gas chromatography-mass spectrometry (GC-MS) and enzyme linked immunosorbent assay (ELISA), respectively. Our results showed that the expression levels of Inpp5e gradually decreased in the forebrain tissues of the control embryos, but no stable trend was observed in the inositol deficiency NTDs embryos. Inpp5e expression in inositol deficiency NTDs embryos was significantly decreased compared with the control tissues. The expression levels of Inpp5e gene and the PtdIns (3,4) P2 levels were also significantly decreased in the inositol deficient cell model. A reduced number and length of primary cilia were observed in NIH3T3 cells when inositol deficient. Three important cilia-related genes (Ift80, Mkks, Smo) were down-regulated significantly in the inositol-deficient NTDs mouse and cell models, and Smo was highly involved in NTDs. In summary, these findings suggested that down-regulation of Inpp5e might be associated with abnormal ciliogenesis during embryonic neurodevelopment, under conditions of inositol deficiency.

Neural tube defects: role of lithium carbonate exposure in embryonic neural development in a murine model.

BACKGROUND: Lithium carbonate (Li2CO3) is widely used in the treatment of clinical-affective psychosis. Exposure to Li2CO3 during pregnancy increases the risk of neural tube defects (NTDs) in offspring, which are severe birth defects of the central nervous system. The mechanism of Li2CO3-induced NTDs remains unclear. METHODS: C57BL/6 mice were injected with different doses of Li2CO3 intraperitoneally on gestational day 7.5 (GD7.5), and embryos collected at GD11.5 and GD13.5. The mechanisms of Li2CO3 exposure-induced NTDs were determined utilizing immunohistochemistry, western blotting, EdU imaging, enzymatic method, gas chromatography-mass spectrometry (GC-MS), ELISA and HE staining. RESULTS: The NTDs incidence was 33.7% following Li2CO3 exposure. Neuroepithelial cell proliferation and phosphohistone H3 level were significantly increased in NTDs embryos, compared with control group (P < 0.01), while the expressing levels of p53 and caspase-3 were significantly decreased. IMPase and GSK-3ß activity was inhibited in Li2CO3-treated maternal and embryonic neural tissues (P < 0.01 and P < 0.05, respectively), along with decreased levels of inositol and metabolites, compared with control groups (P < 0.01). CONCLUSIONS: Lithium-induced NTDs model in C57BL/6 mice was established. Enhanced cell proliferation and decreased apoptosis following lithium exposure were closely associated with the impairment of inositol biosynthesis, which may contribute to lithium-induced NTDs. IMPACT: Impairment of inositol biosynthesis has an important role in lithium exposure-induced NTDs in mice model. Lithium-induced NTDs model on C57BL/6 mice was established. Based on this NTDs model, lithium-induced impairment of inositol biosynthesis resulted in the imbalance between cell proliferation and apoptosis, which may contribute to lithium-induced NTDs. Providing evidence to further understand the molecular mechanisms of lithium-induced NTDs and enhancing its primary prevention.

The Effects of Inositol Metabolism in Pregnant Women on Offspring in the North and South of China.

BACKGROUND Inositol is an essential nutrient for cell growth, survival and embryonic development. Myo-inositol is the predominant form in natural. To investigate the correlation between inositol metabolism and embryonic development, we assessed the metabolic characteristics of myo-inositol, phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3) of pregnant women in the North China (Yangquan and Weihai) and South China (Nanchang and Haikou) China. MATERIAL AND METHODS All data were collected by face-to-face interview during pregnant women health visits using a questionnaire. Plasma levels of myo-inositol, PI(4,5)P2 and PI(3,4,5)P3 from 89 randomly collected pregnant women were detected by gas chromatography-mass spectrometry and enzyme linked immunosorbent assay. RESULTS A total of 400 pregnant women were included in this survey. The plasma levels of myo-inositol and PI(4,5)P2 in the North China group of pregnant women were significantly higher than that in the South China group (P<0.01). The birth weight of fetuses in the North China group was heavier than that in the South China group (P<0.01). The birth length of fetuses in Yangquan was the longest among the 4 cities (P<0.01). The incidence rate of birth defects was 3.05% in the North China group, and 0.0% in the South China group. In bivariate linear correlation analysis, the body weight correlated with myo-inositol (r=0.5044, P<0.0001), PI(4,5)P2 (r=0.5950, P<0.0001) and PI(3,4,5)P3 (r=0.4710, P<0.0001), the body length was correlated with PI(4,5)P2 (r=0.3114, P=0.0035) and PI(3,4,5)P3 (r=0.2638, P<0.0130). CONCLUSIONS The plasma levels of myo-inositol and PI(4,5)P2 in pregnant women had significant difference between the North and the South of China, which might be correlated with fetal development and birth defects.