Maternal exposure to prostaglandin E₂ modifies expression of Wnt genes in mouse brain - An autism connection

Prostaglandin E₂ (PGE₂) is a lipid signaling molecule important for brain development and function. Various genetic and environmental factors can influence the level of PGE₂ and increase the risk of developing Autism Spectrum Disorder (ASD). We have previously shown that in neuronal cell lines and mouse brain, PGE₂ can interfere with the Wnt canonical pathway, which is essential during early brain development. Higher levels of PGE₂ increased Wnt-dependent motility and proliferation of neuroectodermal stem cells, and modified the expression of Wnt genes previously linked to autism disorders. We also recently established a cross-talk between these two pathways in the prenatal mouse brain lacking PGE₂ producing enzyme (COX^-/-). The current study complements the published data and reveals that PGE₂ signaling also converges with the Wnt canonical pathway in the developing mouse brain after maternal exposure to PGE₂ at the onset of neurogenesis. We found significant changes in the expression level of Wnt-target genes, Mmp7, Wnt2, and Wnt3a, during prenatal and early postnatal stages. Interestingly, we observed variability in the expression level of these genes between genetically-identical pups within the same pregnancy. Furthermore, we found that all the affected genes have been previously associated with disorders of the central nervous system, including autism. We determined that prenatal exposure to PGE₂ affects the Wnt pathway at the level of β-catenin, the major downstream regulator of Wnt-dependent gene transcription. We discuss how these results add new knowledge into the molecular mechanisms by which PGE₂ may interfere with neuronal development during critical periods.