Glands of the uterus are essential for the establishment of pregnancy in mice and likely humans. Forkhead box a2 (FOXA2) is a transcription factor expressed specifically in the glands of the uterus and a critical regulator of uterine gland differentiation, development and function. Mice with a conditional deletion of FOXA2 in the adult uterus, created using the lactotransferrin iCre (Ltf-iCre) model, have a morphologically normal uterus with glands, but lack a considerable number of FOXA2-dependent GE-expressed genes. Adult FOXA2 conditional knockout (cKO; Ltf-iCre:Foxa2 flox) mice are infertile due to defective embryo implantation arising from a lack of leukemia inhibitory factor (LIF), a critical implantation factor of uterine gland origin. Intraperitoneal injections of LIF can initiate embryo implantation in the uterus of adult FOXA2 cKO mice with pregnancies maintained to term. Here, we tested the hypothesis that FOXA2-regulated genes in the uterine glands impact development of the decidua, placenta and fetus using a littermate study design. On gestational day (GD) 8.5, the anti-mesometrial and mesometrial decidua transcriptome was noticeably altered in FOXA2 cKO mice. Viable fetuses were reduced in FOXA2 cKO mice on GDs 12.5 and 17.5. Sex-dependent differences in fetal weight, placenta histoarchitecture, and the placenta and metrial gland transcriptome were observed between control and FOXA2 cKO mice. The transcriptome of the placenta with a female fetus was considerably more altered than the placenta with a male fetus in FOXA2 cKO dams. These studies reveal a previously unrecognized biological role for FOXA2 and uterine glands on fetoplacental development that exhibits sexual dimorphism. Thus, uterine glands and, by inference, their products program fetoplacental development with potential sexually dimorphic impacts on offspring health into adulthood.

FOXA2 was conditionally deleted in the uterus. Floxed Foxa2 mice were crossed with or LtfiCre mice to generate conditional knockout animals. Floxed Foxa2f/f mice (stock no. 022620) and LtfiCre mice (stock no. 026030) were obtained from The Jackson Laboratory. Gestational time points were obtained by the mating of 8- to 10-wk old Control (Foxa2f/f) and FOXA2 cKO (LtfiCr/+Foxa2f/f) females to wild-type CD-1 male mice with the day that a vaginal plug was observed was considered day 0.5 of gestation. For FOXA2 cKO dams, mice received i.p. injections of recombinant mouse LIF (10 μg in saline; catalog #554008, BioLegend) at 1000 h and 1800 h on GD 3.5. Freshly collected gestation day 8.5 mesometrial and anti-mesometrial decudua from littermate  control and Foxa2 conditional knockout uterus were snap frozen in liquid nitrogen. Then on gestation day 12.5, placenta and metrial gland from littermate  control and Foxa2 conditional knockout uterus were snap frozen in liquid nitrogen.  Also, freshly collected gestation day 17.5 placenta and metrial gland from littermate  control and Foxa2 conditional knockout uterus were snap frozen in liquid nitrogen. Total RNA was isolated from frozen speciment using a standard TRIzol-based protocol (Catalog 15596026, Thermo Fisher). To eliminate genomic DNA contamination, extracted RNA was treated with DNase I and purified using a RNeasy MinElute Cleanup Kit (Qiagen). The quality and concentration of RNA were determined using a Fragment Analyzer (Advanced Analytical Technologies).  RNA-seq was peformed to profile gene expresion.