Neonatal diethylstilbestrol exposure disrupts uterine epithelial apical-basal polarity and partial EMT state

The developing female reproductive tract is highly sensitive to external hormonal stimulation, which can result in infertility and gynecologic diseases. To determine the underlying mechanisms, we used a mouse model to test the immediate, cell type-specific effects of neonatal exposure to the estrogenic chemical, diethylstilbestrol (DES), on the developing uterus. We found that control uterine epithelium is in a partial epithelial-mesenchymal transition state that is lost following DES exposure. This is accompanied by evidence of premature differentiation including altered apical-basal cell polarity and absence of the Lgr5+ epithelial stem cell population required for uterine gland formation. Cell-cell communication between epithelial and mesenchymal cells is restructured, and Wnt signaling is persistently reduced. The DES-exposed uterine mesenchyme has early signs of fibrosis through increased deposition of extracellular matrix collagen.Mechanistically, DES exposure causes cell type-specific changes in chromatin accessibility and gene expression, most prominently in epithelial cells. These changes can be explained in part by cell-specific alterations in chromatin looping at enhancer regions in concert with alterations in ER binding. These findings suggest that reprogramming cell type-specific differentiation trajectories and extracellular matrix characteristics underlie the long-term phenotypic effects of developmental exposure to estrogenic endocrine disrupting chemicals. These changes lead to functional impairment of adult tissues and increased cancer risk. Significance StatementUterine development is strongly impacted by brief exposure to estrogenic endocrine disruptors, but it is unclear why development is such a sensitive time point. This study employed multiomic analysis to identify cell type-specific uterine developmental trajectories in neonatal mice exposed to the estrogenic chemical, diethylstilbestrol, and compared these to controls. Control epithelium was under the influence of carefully orchestrated Wnt/{beta}-catenin signaling and was in a partial epithelial-to-mesenchymal transition state. DES exposure repressed Wnt/{beta}-catenin signaling and drove the epithelium toward full differentiation, resulting in the loss of both epithelial stem cells and normal apical-basal polarity. These changes provide an explanation for how endocrine disruptors can divert intrinsically programmed developmental trajectories to alter adult organ function.