Classical estrogen signaling in ciliated epithelial cells of the oviduct is nonessential for fertility in female mice
Ciliary action performs a critical role in the oviduct (Fallopian tube), during pregnancy establishment through sperm and egg transport. The disruption of normal ciliary function in the oviduct affects oocyte pick-up and is a contributing factor to female infertility. Estrogen is an important regulator of ciliary action in the oviduct and promotes ciliogenesis in several species. Global loss of estrogen receptor 1 alpha (encoded by Esr1 gene) leads to infertility. Our laboratory has previously shown that ESR1 in the oviductal epithelial cell layer is required for female fertility. Here, we assessed the role of estrogen on transcriptional regulation of ciliated epithelial cells of the oviduct using single-cell RNA-sequencing analysis. We observed minor variations in ciliated cell genes in the proximal region (isthmus and uterotubal junction) of the oviduct. However, E2 treatment had little impact on the gene expression profile of ciliated epithelial cells. To assess the requirement of ESR1 specifically in ciliated cells for female fertility, we conditionally ablated Esr1 from ciliated epithelial cells of the oviduct (called ciliated Esr1d/d mice). Our studies showed that ciliated Esr1d/d females had fertility rates comparable to control females, did not display any disruptions in preimplantation embryo development or embryo transport to the uterus, and had comparable cilia formation to control females. However, we observed some incomplete deletion of Esr1 in the ciliated epithelial cells, especially in the ampulla region. Therefore, more studies are required to definitively determine ESR1 function in ciliated cells of the oviduct. Nevertheless, our data suggest that ESR1 expression in ciliated cells of the oviduct is dispensable for ciliogenesis, but nonessential for female fertility in mice. All genes expressed in scRNA-seq datasets are available for scientific community and separable at https://www.winuthayanon.com/genes/ve2h_cilia/ and https://www.winuthayanon.com/genes/ve2h_allclusters/ Overall design: Wild-type female mice were ovariectomized and treated with 17b-estradiol. After 2 h of injection, oviducts were collected and processed for single cell RNA-sequencing analysis.