Regulation of porcupine-dependent Wnt signaling is essential for uterine development and function

Abstract

Six members of the Wnt family are expressed in the female reproductive tract. Their collective function ensures proper development of the uterus, preparing it for pregnancy during adulthood. Here, we take advantage of the fact that a prerequisite for all Wnt secretion, is located on the X chromosome, to generate females that were mosaic for throughout the reproductive tract. females were mated with progesterone receptor ()-Cre males ( ) to generate females that were heterozygous for Porcupine in all tissues of the female reproductive tract, resulting in mosaicism due to random X-inactivation. We demonstrated that mosaic females are extremely subfertile and exhibit a large spectrum of phenotypes ranging from morphologically normal uteri to uteri with extremely enlarged cystic glands. Decreased fertility in Porcupine mosaic females was not associated with phenotype severity and was observed regardless of whether or not cystic glands were enlarged. By crossing-in a GFP reporter on the wild-type X chromosome, we were able to correlate endometrial gland hyperplasia with a mostly mutant stroma, demonstrating the role of stromal Wnts in the regulation of endometrial gland proliferation. Finally, we demonstrated that fertility issues within mosaic females were due to a reduced response to estrogen and to abnormal Tcf/Lef signaling across the mesometrial-anti-mesometrial axis during the window of implantation.

Neonatal Wnt-dependent Lgr5 positive stem cells are essential for uterine gland development

“…Pharmacological inhibition of endogenous paracrine Wnt secretion in neonate mice using porcupine inhibitor established a similar dependence of uterine gland development on endogenous Wnt signaling, in agreement with similar phenotypes reported for various Wnt KO mouse models 24–26,38 . Conditional Porcn knockout mice exhibit variable uterus phenotypes, with complete ablation compromising only adult endometrial gland maintenance, in contrast to partial knockout, which suppresses proper gland formation 40,41 . The major impairment of endometrial gland formation we observe using pharmacological inhibition of Porcupine function, which targets the epithelial compartment 33 , supports opposing roles for Wnt signaling within the stromal and epithelial compartments during neonatal gland formation.…”

Integrative analysis of the forkhead box A2 (FOXA2) cistrome for the human endometrium

“…A Foxa2 ChIP-Seq study of the postnatal d-12 mouse uterus found that GE-expressed genes with Foxa2 binding intervals were enriched for cell cycle, cell junction, focal adhesion, and WNT signaling (18). Of note, canonical WNT signaling is critical for uterine gland morphogenesis in the neonatal mouse uterus (47,48). In the present study, FOXA2 binding intervals unique to P-phase endometrium contained SOX17, ESR1, ELK1, and nuclear receptor subfamily 4 group A member 2 TFBS motifs; all of those transcription factors are expressed in the GE of the human uterus, and their expression decreases in the MS phase based on RNA-Seq analysis.…”

Molecular Signaling Regulating Endometrium–Blastocyst Crosstalk

“…Animal studies have demonstrated that progesterone treatment during neonatal life impairs gland development and this severely affects fertility, supporting a central role of endometrial glands for embryo implantation [36]. Experimental data suggest that progesterone treatment may affect the expression of genes central to endometrial adenogenesis, including members of the Wnt family [38], whose expression and adenogenic role has been demonstrated in both glands and stroma [39][40][41][42][43][44][45]. A central role of glands in implantation is also suggested by loss-of-function studies of genes involved in epithelial morphogenesis and proliferation in mice, for example, ablation of the cell-cell adhesion molecule Cdh1 results in epithelial disorganization and absence of glands in the neonatal uterus, with consequent infertility [46]; moreover, conditional knock-out of Sox17 in the uterus is associated with impaired endometrial adenogenesis and infertility [47].…”