Porcupine-dependent Wnt activity within the uterine epithelium is essential for fertility

The secretion of mammalian Wnt ligands within the cell is dependent on the activity of Porcupine, a gene located on the X-chromosome that encodes for a membrane-bound O-acyl transferase. Here, we report that postnatal ablation of Porcupine in the uterine luminal epithelium alone results in the decrease in endometrial gland number. Despite having uterine glands, mutant females are completely infertile. Epithelial ablation of Porcupine causes defects in timely apposition of the lumen, along with failure to respond to artificial decidual induction. Interestingly, progesterone supplementation was able to rescue the initiation of decidualization, but the decidua was not maintained and subsequently resorbed. Transcriptome analysis demonstrated that deletion of Porcupine in the epithelium resulted in the stromal dysregulation of members of the Wnt signaling pathway (Lef1, Wnt4, and Wnt16), dysregulation of receptors and ligands in the Notch signaling pathway (Notch1, Notch4, and Dll4) as well as Hoxa10. Our results demonstrate the crucial requirement of Wnt signaling in the epithelium for fertility and demonstrate that epithelial Wnts regulate stromal Wnt gene expression as well as regulating the expression of essential signaling factors and effectors required for successful embryo implantation.