Objectives : Our study aimed to determine whether changes in PGE2 levels affect the function of embryonic neural cell function, to investigate the potential cross-talk between PGE2 and Wnt signaling pathways, and to elucidate how these molecules may cause abnormal neuronal development.
Methods : Mouse neuroectodermal (NE-4C) stem cells were used as an in vitro experimental model. The study was conducted on undifferentiated NE-4C cells and cells differentiated into neurons and astrocytes. Cells were treated with various concentrations of PGE2 or misoprostol to determine the effects on gene and protein expression, as well as cell behaviour. Quantitative real-time PCR was used to measure mRNA expression with SYBR Green reagent or Custom TaqMan® Array Plates. Protein analysis was completed using western blot technique. Cell behaviour such as cell movement and growth measurements was recorded using Nikon Eclipse Ti-E microscope with a specialized object tracking module.
Results : We show that the EP receptor expression changed between undifferentiated and differentiated cells. Relative to undifferentiated NE-4C cells, neurons had a decrease in EP1 and an increase in EP3β and EP3γ expression. Similarly, astrocytes had a decrease in EP1 but an increase in EP3α and EP4 expression. This could indicate that committed and uncommitted cells respond differently to PGE2. PGE2 concentration-dependent treatment also regulated the level of EP3α,β,γ and EP4 receptor expression suggesting that exposure to varying doses of PGE2 could result in differential downstream effects. Interestingly, we also determined that PGE2 treatment modifies the expression of various Wnt-dependent target genes. Furthermore, PGE2 appeared to attenuate Wnt-dependent cell behaviour by modifying average velocity, path length, distance, and cell division.
Conclusions : These results indicated that PGE2 may regulate neuronal stem cell function via activation of EP receptors in a dose-dependent manner and that it may interfere with other key developmental pathways such as the Wnt signaling pathway. This study expands our knowledge of the important role PGE2 signaling may have in the developing nervous system and its potential contribution to the pathology of ASDs.