Constitutive activation of smoothened leads to female infertility and altered uterine differentiation in the mouse

Endometrial zinc transporter Slc39a10/Zip10 is indispensable for progesterone responsiveness and successful pregnancy in mice

Zinc is a critical trace element that is important for various biological functions including male and female reproductive systems, but the molecular mechanisms that underlie fertility have been unclear. We show here that zinc signaling in the endometrial tissue is indispensable for successful pregnancy in mice. We observed that a uterine-specific genetic deletion of Slc39a10/Zip10, which encodes one of the zinc transporters to elevate the cytoplasmic level of zinc, results in female infertility due to failure of embryo invasion into the endometrium and subsequent embryonic loss. Zip10 mRNA is expressed in uterine tissues, especially in the decidualizing stromal cells during embryo implantation. The absence of ZIP10 leads to attenuation of progesterone-progesterone receptor (PGR) signals between the epithelium and the stroma, including abnormal expression of the PGR and its target molecules in both the epithelium and stroma in vivo. We found that depletion of intracytoplasmic zinc ions due to loss of ZIP10 disrupts the change in nuclear-to-cytoplasmic localization of GLI1, which is critical for PGR signaling in the decidualizing stromal cells in vitro not only in mice but also in humans. Our findings (i) highlight a biological relevance of ZIP10-mediated zinc homeostatic regulation in the establishment of a successful pregnancy and (ii) will help to prevent infertility in humans.

Decoding Müllerian Duct Epithelial Regionalization

Müllerian ducts (MD), also known as paramesonephric ducts, are the primordial anlage of the female reproductive tract organs including the oviduct, uterus, cervix and upper vagina along the craniocaudal axis. Although the general architecture of MD-derived organs is conserved, each organ possesses their unique epithelial structures and cell types to confer their region-specific functions, which collectively coordinate successful fertilization and pregnancy. MD epithelial fate decisions and differentiation along the craniocaudal axis is dependent on spatiotemporal regulation of intrinsic transcription factors and extrinsic signals derived from the mesenchyme. Findings from genetic mouse models, single-cell sequencing studies, and organoid cultures have significantly advanced our understanding of the cellular and molecular mechanisms of MD regionalization. In this review, we first discuss the diversity of epithelial morphologies and cell types in the female reproductive tract organs. Then, we discuss the roles of key transcription factors (Hox, transcriptional cascade driving multiciliogenesis, Foxa2, and P63), signaling pathways (estrogen/ESR1, Wnt/β-catenin, hedgehog, and retinoic acid), and epigenetic factors (microRNAs, chromatin remodeling factors, and histone modification enzymes) in region-specific MD differentiation. Further deciphering molecular mechanisms of MD craniocaudal patterning will open new avenues to improve our strategies for prevention, diagnosis, and treatment of Müllerian anomalies and female reproductive tract disorders.

Hedgehog signaling is required for endometrial remodeling and myometrial homeostasis in the cycling mouse uterus

Decades of work demonstrate that the mammalian estrous cycle is controlled by cycling steroid hormones. However, the signaling mechanisms that act downstream, linking hormonal action to the physical remodeling of the cycling uterus, remain unclear. To address this issue, we analyzed gene expression at all stages of the mouse estrous cycle. Strikingly, we found that several genetic programs well-known to control tissue morphogenesis in developing embryos displayed cyclical patterns of expression. We find that most of the genetic architectures of Hedgehog signaling (ligands, receptors, effectors, and transcription factors) are transcribed cyclically in the uterus, and that conditional disruption of the Hedgehog receptor smoothened not only elicits a failure of normal cyclical thickening of the endometrial lining but also induces aberrant deformation of the uterine smooth muscle. Together, our data shed light on the mechanisms underlying normal uterine remodeling specifically and cyclical gene expression generally.

TRIM28 modulates nuclear receptor signaling to regulate uterine function

Estrogen and progesterone, acting through their cognate receptors the estrogen receptor α (ERα) and the progesterone receptor (PR) respectively, regulate uterine biology. Using rapid immunoprecipitation and mass spectrometry (RIME) and co-immunoprecipitation, we identified TRIM28 (Tripartite motif containing 28) as a protein which complexes with ERα and PR in the regulation of uterine function. Impairment of TRIM28 expression results in the inability of the uterus to support early pregnancy through altered PR and ERα action in the uterine epithelium and stroma by suppressing PR and ERα chromatin binding. Furthermore, TRIM28 ablation in PR-expressing uterine cells results in the enrichment of a subset of TRIM28 positive and PR negative pericytes and epithelial cells with progenitor potential. In summary, our study reveals the important roles of TRIM28 in regulating endometrial cell composition and function in women, and also implies its critical functions in other hormone regulated systems.

A multi-tissue transcriptomic landscape of female mice in estrus and diestrus provides clues for precision medicine

Female reproductive cycle, also known as menstrual cycle or estrous cycle in primate or non-primate mammals, respectively, dominates the reproductive processes in non-pregnant state. However, in addition to reproductive tissues, reproductive cycle could also perform global regulation because the receptors of two major female hormones fluctuating throughout the cycle, estrogen and progesterone, are widely distributed. Therefore, a multi-tissue gene expression landscape is in continuous demand for better understanding the systemic changes during the reproductive cycle but remains largely undefined. Here we delineated a transcriptomic landscape covering 15 tissues of C57BL/6J female mice in two phases of estrous cycle, estrus and diestrus, by RNA-sequencing. Then, a number of genes, pathways, and transcription factors involved in the estrous cycle were revealed. We found the estrous cycle could widely regulate the neuro-functions, immuno-functions, blood coagulation and so on. And behind the transcriptomic alteration between estrus and diestrus, 13 transcription factors may play important roles. Next, bioinformatics modeling with 1,263 manually curated gene signatures of various physiological and pathophysiological states systematically characterized the beneficial/deleterious effects brought by estrus/diestrus on individual tissues. We revealed that the estrous cycle has a significant effect on cardiovascular system (aorta, heart, vein), in which the anti-hypertensive pattern in aorta induced by estrus is one of the most striking findings. Inspired by this point, we validated that two hypotensive drugs, felodipine and acebutolol, could exhibit significantly enhanced efficacy in estrus than diestrus by mouse and rat experiments. Together, this study provides a valuable data resource for investigating reproductive cycle from a transcriptomic perspective, and presents models and clues for investigating precision medicine associated with reproductive cycle.

Increased FOXL2 expression alters uterine structures and functions†

The transcription factor forkhead box L2 (FOXL2) regulates sex differentiation and reproductive function. Elevated levels of this transcription factor have been observed in the diseases of the uterus, such as endometriosis. However, the impact of elevated FOXL2 expression on uterine physiology remains unknown. In order to determine the consequences of altered FOXL2 in the female reproductive axis, we generated mice with over-expression of FOXL2 (FOXL2OE) by crossing Foxl2LsL/+ with the Progesterone receptor Pgrcre model. FOXL2OE uterus showed severe morphological abnormality including abnormal epithelial stratification, blunted adenogenesis, increased endometrial fibrosis, and disrupted myometrial morphology. In contrast, increasing FOXL2 levels specifically in uterine epithelium by crossing the Foxl2LsL/+ with the lactoferrin Ltficre mice resulted in the eFOXL2OE mice with uterine epithelial stratification but without defects in endometrial fibrosis and adenogenesis, demonstrating a role of the endometrial stroma in the uterine abnormalities of the FOXL2OE mice. Transcriptomic analysis of 12 weeks old Pgrcre and FOXL2OE uterus at diestrus stage showed multiple signaling pathways related with cellular matrix, wnt/β-catenin, and altered cell cycle. Furthermore, we found FOXL2OE mice were sterile. The infertility was caused in part by a disruption of the hypophyseal ovarian axis resulting in an anovulatory phenotype. The FOXL2OE mice failed to show decidual responses during artificial decidualization in ovariectomized mice demonstrating the uterine contribution to the infertility phenotype. These data support that aberrantly increased FOXL2 expressions in the female reproductive tract can disrupt ovarian and uterine functions.

Uterine Glands: Developmental Biology and Functional Roles in Pregnancy

All mammalian uteri contain glands in the endometrium that develop only or primarily after birth. Gland development or adenogenesis in the postnatal uterus is intrinsically regulated by proliferation, cell-cell interactions, growth factors and their inhibitors, as well as transcription factors, including forkhead box A2 (FOXA2) and estrogen receptor α (ESR1). Extrinsic factors regulating adenogenesis originate from other organs, including the ovary, pituitary, and mammary gland. The infertility and recurrent pregnancy loss observed in uterine gland knockout sheep and mouse models support a primary role for secretions and products of the glands in pregnancy success. Recent studies in mice revealed that uterine glandular epithelia govern postimplantation pregnancy establishment through effects on stromal cell decidualization and placental development. In humans, uterine glands and, by inference, their secretions and products are hypothesized to be critical for blastocyst survival and implantation as well as embryo and placental development during the first trimester before the onset of fetal-maternal circulation. A variety of hormones and other factors from the ovary, placenta, and stromal cells impact secretory function of the uterine glands during pregnancy. This review summarizes new information related to the developmental biology of uterine glands and discusses novel perspectives on their functional roles in pregnancy establishment and success.

Med12 regulates ovarian steroidogenesis, uterine development and maternal effects in the mammalian egg

The transcriptional factor MED12 is part of the essential mediator transcriptional complex that acts as a transcriptional coactivator in all eukaryotes. Missense gain-of-function mutations in human MED12 are associated with uterine leiomyomas, yet the role of MED12 deficiency in tumorigenesis and reproductive biology has not been fully explored. We generated a Med12 reproductive conditional knockout mouse model to evaluate its role in uterine mesenchyme, granulosa cells, and oocytes. Mice heterozygous for Med12 deficiency in granulosa cells and uterus (Med12fl/+ Amhr2-Cre) were subfertile, while mice homozygous for Med12 deficiency in granulosa cells and uterus (Med12fl/fl Amhr2-Cre) were infertile. Morphological and histological analysis of the Med12fl/fl Amhr2-Cre reproductive tract revealed atrophic uteri and hyperchromatic granulosa cells with disrupted expression of Lhcgr, Esr1, and Esr2. Med12fl/fl Amhr2-Cre mice estrous cycle was disrupted, and serum analysis showed blunted rise in estradiol in response to pregnant mare serum gonadotropin. Uterine atrophy was partially rescued by exogenous steroid supplementation with dysregulation of Notch1 and Smo expression in steroid supplemented Med12fl/fl Amhr2-Cre uteri, indicating intrinsic uterine defects. Oocyte-specific ablation of Med12 caused infertility without disrupting normal folliculogenesis and ovulation, consistent with maternal effects of Med12 in early embryo development. These results show the critical importance of Med12 in reproductive tract development and that Med12 loss of function does not cause tumorigenesis in reproductive tissues.

SOX17 regulates uterine epithelial-stromal cross-talk acting via a distal enhancer upstream of Ihh

Mammalian pregnancy depends on the ability of the uterus to support embryo implantation. Previous studies reveal the Sox17 gene as a downstream target of the Pgr-Gata2-dependent transcription network that directs genomic actions in the uterine endometrium receptive for embryo implantation. Here, we report that ablating Sox17 in the uterine epithelium impairs leukemia inhibitory factor (LIF) and Indian hedgehog homolog (IHH) signaling, leading to failure of embryo implantation. In vivo deletion of the SOX17-binding region 19 kb upstream of the Ihh locus by CRISPR-Cas technology reduces Ihh expression specifically in the uterus and alters proper endometrial epithelial-stromal interactions, thereby impairing pregnancy. This SOX17-binding interval is also bound by GATA2, FOXA2, and PGR. This cluster of transcription factor binding is common in 737 uterine genes and may represent a key regulatory element essential for uterine epithelial gene expression.

Molecular mechanisms of embryonic implantation in mammals: Lessons from the gene manipulation of mice

BACKGROUND

Human infertility has become a serious and social issue all over the world, especially in developed countries. Numerous types of assisted reproductive technology have been developed and are widely used to treat infertility. However, pregnancy outcomes require further improvement. It is essential to understand the cross-talk between the uterus (mother) and the embryo (fetus) in pregnancy, which is a very complicated event.

METHODS

The mammalian uterus requires many physiological and morphological changes for pregnancy-associated events, including implantation, decidualization, placentation, and parturition, to occur. Here is discussed recent advances in the knowledge of the molecular mechanisms underlying these reproductive events - in particular, embryonic implantation and decidualization - based on original and review articles.

MAIN FINDINGS RESULTS

In mice, embryonic implantation and decidualization are regulated by two steroid hormones: estrogen and progesterone. Along with these hormones, cytokines, cell-cycle regulators, growth factors, and transcription factors have essential roles in implantation and decidualization in mice.

CONCLUSION

Recent studies using the gene manipulation of mice have given considerable insight into the molecular mechanisms underlying embryonic implantation and decidualization. However, as most of the findings are based on mice, comparative research using different mammalian species will be useful for a better understanding of the species-dependent differences that are associated with reproductive events, including embryonic implantation.

The ERM family member Merlin is required for endometrial gland morphogenesis

Disruption of endometrial gland formation or function can cause female infertility. Formation of endometrial glands via tubulogenesis of luminal epithelial cells requires the establishment and maintenance of cell polarity and cell adhesion. The FERM domain-containing protein Merlin coordinates epithelial cell polarity and cell adhesion and is critical for epithelial tissue function in the skin and kidney. We now demonstrate a requirement for Merlin in endometrial gland development. Conditional deletion of Merlin in the endometrium results in female infertility caused by the absence of gland formation. Interestingly, we observed glandular epithelial markers within discrete groups of cells in the Merlin-deficient luminal epithelium. Wnt signaling, a pathway necessary for endometrial gland development is maintained in Merlin-deficient endometrium, suggesting the glandular fate program is active. Instead, we observe increased levels of apical actin and markers indicative of high membrane tension on the basal surface of the Merlin-deficient luminal epithelium. These findings suggest that the structural integrity of the luminal epithelium during gland formation is required for appropriate endometrial tubulogenesis and tissue function. Moreover, our work implicates Merlin-dependent regulation of mechanical tension in the proper formation of endometrial gland architecture and function.

A historical review of blastocyst implantation research

Research development on blastocyst implantation was reviewed in three sections: primate implantation, ungulate farm animal implantation, and the general process of blastocyst implantation in small rodents. Future research directions of this area are suggested.

Progesterone Receptor Regulation of Uterine Adaptation for Pregnancy

Progesterone acts through the progesterone receptor to direct physiological adaption of the uterus in preparation and completion of pregnancy. Genome-wide transcriptome and cistrome analyses have uncovered new members and novel modifiers of the progesterone signaling pathway. Genetically engineered mice allow functional assessment of newly identified genes in vivo and provide insights on the impact of progesterone receptor-dependent molecular mechanisms on pregnancy at the organ system level. Progesterone receptor isoforms collectively mediate progesterone signaling via their distinct and common downstream target genes, which makes the stoichiometry of isoforms relevant in modifying the progesterone activity. This review discusses recent advances on the discovery of the progesterone receptor network, with special focus on the endometrium at early pregnancy and myometrium during parturition.

Decreased epithelial progesterone receptor A at the window of receptivity is required for preparation of the endometrium for embryo attachment

The precise timing of progesterone signaling through its cognate receptor, the progesterone receptor (PGR), is critical for the establishment and maintenance of pregnancy. Loss of PGR expression in the murine uterine epithelium during the preimplantation period is a marker for uterine receptivity and embryo attachment. We hypothesized that the decrease in progesterone receptor A (PGRA) expression is necessary for successful embryo implantation. To test this hypothesis, a mouse model constitutively expressing PGRA (mPgrALsL/+) was generated. Expression of PGRA in all uterine compartments (Pgrcre) or uterine epithelium (Wnt7acre) resulted in infertility with defects in embryo attachment and stromal decidualization. Expression of critical PGRA target genes, indian hedgehog, and amphiregulin (Areg), was maintained through the window of receptivity while the estrogen receptor target gene, the leukemia inhibitory factor (Lif), a key regulator of embryo receptivity, was decreased. Transcriptomic and cistromic analyses of the mouse uterus at day 4.5 of pregnancy identified an altered group of genes regulating molecular transport in the control of fluid and ion levels within the uterine interstitial space. Additionally, LIF and its cognate receptor, the leukemia inhibitory factor receptor (LIFR), exhibited PGR-binding events in regions upstream of the transcriptional start sites, suggesting PGRA is inhibiting transcription at these loci. Therefore, downregulation of the PGRA isoform at the window of receptivity is necessary for the attenuation of hedgehog signaling, transcriptional activation of LIF signaling, and modulation of solutes and fluid, producing a receptive environment for the attaching embryo.

Oestrogen, progesterone and stem cells: the discordant trio in endometriosis?

Oestrogen–progesterone signalling is highly versatile and critical for the maintenance of healthy endometrium in humans. The genomic and nongenomic signalling cascades initiated by these hormones in differentiated cells of endometrium have been the primary focus of research since 1920s. However, last decade of research has shown a significant role of stem cells in the maintenance of a healthy endometrium and the modulatory effects of hormones on these cells. Endometriosis, the growth of endometrium outside the uterus, is very common in infertile patients and the elusiveness in understanding of disease pathology causes hindrance in selection of treatment approaches to enhance fertility. In endometriosis, the stem cells are dysfunctional as it can confer progesterone resistance to their progenies resulting in disharmony of hormonal orchestration of endometrial homeostasis. The bidirectional communication between stem cell signalling pathways and oestrogen–progesterone signalling is found to be disrupted in endometriosis though it is not clear which precedes the other. In this paper, we review the intricate connection between hormones, stem cells and the cross-talks in their signalling cascades in normal endometrium and discuss how this is deregulated in endometriosis. Re-examination of the oestrogen–progesterone dependency of endometrium with a focus on stem cells is imperative to delineate infertility associated with endometriosis and thereby aid in designing better treatment modalities.

Hormone dependent uterine epithelial-stromal communication for pregnancy support

Human fertility is a relatively inefficient process. Despite the presence of visibly healthy embryos, 30% of pregnancies generated by assisted reproductive technology (ART) fail before the second trimester. The uterine microenvironment plays a critical role in establishing and maintaining a successful pregnancy that requires coordinated communication between the epithelial and stromal cells of the endometrium. The epithelial cells must cease proliferation and become permissive for the conceptus (embryo and associated extraembryonic membranes), while the stromal cells undergoes mesenchymal-to-epithelioid transformation to form the decidua in support of subsequent embryo development. The ovarian steroids Estrogen (E2) and Progesterone (P4) are the major hormones governing these processes. These hormones act via their nuclear receptors, the estrogen receptor, ESR1, and progesterone receptor, PGR, to direct the transcription of genes that orchestrate epithelial and stromal cell communication. This review will discuss the molecular mechanisms utilized by steroid hormones that regulate uterine receptivity, as well, establish and maintain pregnancy.

Forkhead box a2 (FOXA2) is essential for uterine function and fertility

Establishment of pregnancy is a critical event, and failure of embryo implantation and stromal decidualization in the uterus contribute to significant numbers of pregnancy losses in women. Glands of the uterus are essential for establishment of pregnancy in mice and likely in humans. Forkhead box a2 (FOXA2) is a transcription factor expressed specifically in the glands of the uterus and is a critical regulator of postnatal uterine gland differentiation in mice. In this study, we conditionally deleted FOXA2 in the adult mouse uterus using the lactotransferrin Cre (Ltf-Cre) model and in the neonatal mouse uterus using the progesterone receptor Cre (Pgr-Cre) model. The uteri of adult FOXA2-deleted mice were morphologically normal and contained glands, whereas the uteri of neonatal FOXA2-deleted mice were completely aglandular. Notably, adult FOXA2-deleted mice are completely infertile because of defects in blastocyst implantation and stromal cell decidualization. Leukemia inhibitory factor (LIF), a critical implantation factor of uterine gland origin, was not expressed during early pregnancy in adult FOXA2-deleted mice. Intriguingly, i.p. injections of LIF initiated blastocyst implantation in the uteri of both gland-containing and glandless adult FOXA2-deleted mice. Although pregnancy was rescued by LIF and was maintained to term in uterine gland-containing adult FOXA2-deleted mice, pregnancy failed by day 10 in neonatal FOXA2-deleted mice lacking uterine glands. These studies reveal a previously unrecognized role for FOXA2 in regulation of adult uterine function and fertility and provide original evidence that uterine glands and, by inference, their secretions play important roles in blastocyst implantation and stromal cell decidualization.

Endometrial Expression of Steroidogenic Factor 1 Promotes Cystic Glandular Morphogenesis

Epigenetic silencing of steroidogenic factor 1 (SF1) is lost in endometriosis, potentially contributing to de novo local steroidogenesis favoring inflammation and growth of ectopic endometrial tissue. In this study, we examine the impact of SF1 expression in the eutopic uterus by a novel mouse model that conditionally expresses SF1 in endometrium. In vivo SF1 expression promoted the development of enlarged endometrial glands and attenuated estrogen and progesterone responsiveness. Endometriosis induction by autotransplantation of uterine tissue to the mesenteric membrane resulted in the increase in size of ectopic lesions from SF1-expressing mice. By integrating the SF1-dependent transcriptome with the whole genome binding profile of SF1, we identified uterine-specific SF1-regulated genes involved in Wingless and Progesterone receptor-Hedgehog-Chicken ovalbumin upstream promoter transcription factor II signaling for gland development and epithelium-stroma interaction, respectively. The present results indicate that SF1 directly contributes to the abnormal uterine gland morphogenesis, an inhibition of steroid hormone signaling and activation of an immune response, in addition to previously postulated estrogen production.

Constitutive Notch Signaling Causes Abnormal Development of the Oviducts, Abnormal Angiogenesis, and Cyst Formation in Mouse Female Reproductive Tract

The Notch signaling pathway is critical for the differentiation of many tissues and organs in the embryo. To study the consequences of Notch1 gain-of-function signaling on female reproductive tract development, we used a cre-loxP strategy and Amhr2-cre transgene to generate mice with conditionally activated Notch1 (Rosa(Notch1)). The Amhr2-cre transgene is expressed in the mesenchyme of developing female reproductive tract and in granulosa cells in the ovary. Double transgenic Amhr2-cre, Rosa(Notch1) females were infertile, whereas control Rosa(Notch1) mice had normal fertility. All female reproductive organs in mutants showed hemorrhaging of blood vessels progressing with age. The mutant oviducts did not develop coiling, and were instead looped around the ovary. There were multiple blockages in the lumen along the oviduct length, creating a barrier for sperm or oocyte passage. Mutant females demonstrated inflamed uteri with increased vascularization and an influx of inflammatory cells. Additionally, older females developed ovarian, oviductal, and uterine cysts. The significant change in gene expression was detected in the mutant oviduct expression of Wnt4, essential for female reproductive tract development. Similar oviductal phenotypes have been detected previously in mice with activated Smo and in beta-catenin, Wnt4, Wnt7a, and Dicer conditional knockouts, indicating a common regulatory pathway disrupted by these genetic abnormalities.

Uterine inactivation of muscle segment homeobox (Msx) genes alters epithelial cell junction proteins during embryo implantation

Embryo implantation requires that the uterus differentiate into the receptive state. Failure to attain uterine receptivity will impede blastocyst attachment and result in a compromised pregnancy. The molecular mechanism by which the uterus transitions from the prereceptive to the receptive stage is complex, involving an intricate interplay of various molecules. We recently found that mice with uterine deletion ofMsxgenes (Msx1(d/d)/Msx2(d/d)) are infertile because of implantation failure associated with heightened apicobasal polarity of luminal epithelial cells during the receptive period. However, information on Msx's roles in regulating epithelial polarity remains limited. To gain further insight, we analyzed cell-type-specific gene expression by RNA sequencing of separated luminal epithelial and stromal cells by laser capture microdissection fromMsx1(d/d)/Msx2(d/d)and floxed mouse uteri on d 4 of pseudopregnancy. We found that claudin-1, a tight junction protein, and small proline-rich (Sprr2) protein, a major component of cornified envelopes in keratinized epidermis, were substantially up-regulated inMsx1(d/d)/Msx2(d/d)uterine epithelia. These factors also exhibited unique epithelial expression patterns at the implantation chamber (crypt) inMsx1(f/f)/Msx2(f/f)females; the patterns were lost inMsx1(d/d)/Msx2(d/d)epithelia on d 5, suggesting important roles during implantation. The results suggest thatMsxgenes play important roles during uterine receptivity including modulation of epithelial junctional activity.-Sun, X., Park, C. B., Deng, W., Potter, S. S., Dey, S. K. Uterine inactivation of muscle segment homeobox (Msx) genes alters epithelial cell junction proteins during embryo implantation.

Hedgehog signaling and steroidogenesis

Since its discovery nearly 30 years ago, the Hedgehog (Hh) signaling pathway has been shown to be pivotal in many developmental and pathophysiological processes in several steroidogenic tissues, including the testis, ovary, adrenal cortex, and placenta. New evidence links the evolutionarily conserved Hh pathway to the steroidogenic organs, demonstrating how Hh signaling can influence their development and homeostasis and can act in concert with steroids to mediate physiological functions. In this review, we highlight the role of the components of the Hh signaling pathway in steroidogenesis of endocrine tissues.

Development and Characterization of Uterine Glandular Epithelium Specific Androgen Receptor Knockout Mouse Model

While estrogen action is the major driver of uterine development, androgens acting via the androgen receptor (AR) may also promote uterine growth as suggested by uterine phenotypes in global AR knockout (ARKO) female mice. Because AR is expressed in uterine endometrial glands, we generated (Cre/loxP) uterine gland epithelium-specific ARKO (ugeARKO) to determine the role of endometrial gland-specific androgen actions. However, AR in uterine gland epithelium may not be required for normal uterine development and function because ugeARKO females had normal uterine development and fertility. To determine if exogenous androgens acting via AR can fully support uterine growth in the absence of estrogens, the ARKO and ugeARKO females were ovariectomized and treated with supraphysiological doses of testosterone or dihydrotestosterone (nonaromatizable androgen). Both dihydrotestosterone and testosterone supported full uterine regrowth in wild-type females while ARKO females had no regrowth (comparable to ovariectomized only). These findings suggest that androgens acting via AR can promote full uterine regrowth in the absence of estrogens. The ugeARKO had 50% regrowth when compared to intact uterine glands, and histomorphologically, both the endometrial and myometrial areas were significantly (P < 0.05) reduced, suggesting glandular epithelial AR located in the endometrium may indirectly modify myometrial development. Additionally, to confirm Cre function in endometrial glands, we generated uge-specific PTEN knockout mouse model. The ugePTEN knockout females developed severe endometrial hyperplasia and therefore present a novel model for future research.

The absence of the embryo in the pseudopregnant uterus alters the deposition of some ECM molecules during decidualization in mice

The embryo-implantation promotes deep changes in the uterus resulting in the formation of a new structure at the maternal-fetal interface, the decidua. Decidualization can also be induced in pseudopregnant rodents resulting in a structure called deciduoma that is morphologically and functionally similar to the decidua. Previous studies from our and other laboratories demonstrate that in rodents, decidualization of the endometrium requires remarkable remodeling of the endometrial extracellular matrix (ECM) that is mainly coordinated by estradiol and progesterone. The influence of the embryo in this process, however, has not yet been investigated. To enlarge the knowledge on this subject, the present study investigates the behavior of a set of ECM molecules, in the absence of paracrine cues originated from the embryo. For that deciduoma was induced in pseudopregnant Swiss mice, and the distribution of collagen types I, III, IV, V and the proteoglycans decorin and biglycan was investigated by immunolabeling from the fifth to the eighth day of pseudopregnancy. It was observed the deposition of collagen types III and IV as well as decorin and biglycan was similar to that previously described by our group in the decidua. However, in the absence of the embryo, some differences occur in the distribution of collagen types I and V, suggesting that beside the major role of ovarian hormones on the endometrial ECM remodeling, molecular signals originated from the conceptus may influence this process.

Lineage specification of ovarian theca cells requires multicellular interactions via oocyte and granulosa cells

Organogenesis of the ovary is a highly orchestrated process involving multiple lineage determinations of ovarian surface epithelium, granulosa cells, and theca cells. While the sources of ovarian surface epithelium and granulosa cells are known, the origin(s) of theca progenitor cells have not been definitively identified. Here we show that theca cells derive from two sources: Wt1⁺ cells indigenous to the ovary and Gli1⁺ mesenchymal cells migrated from the mesonephros. These progenitors acquire theca lineage marker Gli1 in response to paracrine signals Desert hedgehog (Dhh) and Indian hedgehog (Ihh) from granulosa cells. Ovaries lacking Dhh/Ihh exhibit theca layer loss, blunted steroid production, arrested folliculogenesis, and failure to form corpora lutea. Production of Dhh/Ihh in granulosa cells requires Growth differentiation factor 9 (GDF9) from the oocyte. Our studies provide the first genetic evidence for the origins of theca cells and reveal a multicellular interaction critical for the formation of a functional theca.

Uterine glands: biological roles in conceptus implantation, uterine receptivity and decidualization

All mammalian uteri contain glands in the endometrium that synthesize or transport and secrete substances essential for survival and development of the conceptus (embryo/fetus and associated extraembryonic membranes). This review summarizes information related to the biological roles of uterine glands and their secretions in uterine receptivity, blastocyst/conceptus survival and implantation, and stromal cell decidualization. Studies with the ovine uterine gland knockout (UGKO) model support a primary role for uterine glands and, by inference, their secretions present in uterine luminal fluid histrotroph for conceptus survival and development. In rodents, studies with mutant and progesterone-induced UGKO mice found that uterine glands and their secretions are unequivocally required for establishment of uterine receptivity and blastocyst implantation and also may influence blastocyst trophectoderm activation and stromal cell decidualization in the uterus. Similarly in humans, histotroph from uterine glands appears critical for blastocyst implantation, uterine receptivity, and conceptus nutrition during the first trimester and uterine glands likely have a role in stromal cell decidualization. An increased understanding of uterine gland biology is important for diagnosis, prevention and treatment of fertility problems, particularly infertility and recurrent pregnancy loss, in domestic animals and humans.

Cyclic decidualization of the human endometrium in reproductive health and failure

Decidualization denotes the transformation of endometrial stromal fibroblasts into specialized secretory decidual cells that provide a nutritive and immunoprivileged matrix essential for embryo implantation and placental development. In contrast to most mammals, decidualization of the human endometrium does not require embryo implantation. Instead, this process is driven by the postovulatory rise in progesterone levels and increasing local cAMP production. In response to falling progesterone levels, spontaneous decidualization causes menstrual shedding and cyclic regeneration of the endometrium. A growing body of evidence indicates that the shift from embryonic to maternal control of the decidual process represents a pivotal evolutionary adaptation to the challenge posed by invasive and chromosomally diverse human embryos. This concept is predicated on the ability of decidualizing stromal cells to respond to individual embryos in a manner that either promotes implantation and further development or facilitates early rejection. Furthermore, menstruation and cyclic regeneration involves stem cell recruitment and renders the endometrium intrinsically capable of adapting its decidual response to maximize reproductive success. Here we review the endocrine, paracrine, and autocrine cues that tightly govern this differentiation process. In response to activation of various signaling pathways and genome-wide chromatin remodeling, evolutionarily conserved transcriptional factors gain access to the decidua-specific regulatory circuitry. Once initiated, the decidual process is poised to transit through distinct phenotypic phases that underpin endometrial receptivity, embryo selection, and, ultimately, resolution of pregnancy. We discuss how disorders that subvert the programming, initiation, or progression of decidualization compromise reproductive health and predispose for pregnancy failure.

Biological roles of uterine glands in pregnancy

All mammalian uteri contain glands in the endometrium that synthesize or transport and secrete substances essential for survival and development of the conceptus (embryo/fetus and associated extraembryonic membranes). This review summarizes information related to the biological roles of uterine glands and their secretions in blastocyst/conceptus survival and implantation, uterine receptivity, and stromal cell decidualization in humans and animal models. The infertility and recurrent pregnancy loss observed in the ovine uterine gland knockout (UGKO) model unequivocally supports a primary role for uterine glands and, by inference, their secretions present in uterine luminal fluid in survival and development of the conceptus. Further, studies with mutant and progesterone-induced UGKO mice found that uterine glands and their secretions are required for establishment of uterine receptivity and blastocyst implantation as well as stromal cell decidualization. Similarly in humans, uterine glands and their secretory products are likely critical regulators of blastocyst implantation, uterine receptivity, and conceptus growth and development during the first trimester. Circumstantial evidence suggests that deficient glandular activity may be a causative factor in pregnancy failure and complications in humans. Thus, an increased understanding of uterine gland biology is important for diagnosis, prevention, and treatment of fertility and pregnancy problems in mammals.

Novel DNA motif binding activity observed in vivo with an estrogen receptor α mutant mouse

Estrogen receptor α (ERα) interacts with DNA directly or indirectly via other transcription factors, referred to as "tethering." Evidence for tethering is based on in vitro studies and a widely used "KIKO" mouse model containing mutations that prevent direct estrogen response element DNA- binding. KIKO mice are infertile, due in part to the inability of estradiol (E2) to induce uterine epithelial proliferation. To elucidate the molecular events that prevent KIKO uterine growth, regulation of the pro-proliferative E2 target gene Klf4 and of Klf15, a progesterone (P4) target gene that opposes the pro-proliferative activity of KLF4, was evaluated. Klf4 induction was impaired in KIKO uteri; however, Klf15 was induced by E2 rather than by P4. Whole uterine chromatin immunoprecipitation-sequencing revealed enrichment of KIKO ERα binding to hormone response elements (HREs) motifs. KIKO binding to HRE motifs was verified using reporter gene and DNA-binding assays. Because the KIKO ERα has HRE DNA-binding activity, we evaluated the "EAAE" ERα, which has more severe DNA-binding domain mutations, and demonstrated a lack of estrogen response element or HRE reporter gene induction or DNA-binding. The EAAE mouse has an ERα null-like phenotype, with impaired uterine growth and transcriptional activity. Our findings demonstrate that the KIKO mouse model, which has been used by numerous investigators, cannot be used to establish biological functions for ERα tethering, because KIKO ERα effectively stimulates transcription using HRE motifs. The EAAE-ERα DNA-binding domain mutant mouse demonstrates that ERα DNA-binding is crucial for biological and transcriptional processes in reproductive tissues and that ERα tethering may not contribute to estrogen responsiveness in vivo.

Progesterone signaling inhibits cervical carcinogenesis in mice

Human papillomavirus is the main cause of cervical cancer, yet other nonviral cofactors are also required for the disease. The uterine cervix is a hormone-responsive tissue, and female hormones have been implicated in cervical carcinogenesis. A transgenic mouse model expressing human papillomavirus oncogenes E6 and/or E7 has proven useful to study a mechanism of hormone actions in the context of this common malignancy. Estrogen and estrogen receptor α are required for the development of cervical cancer in this mouse model. Estrogen receptor α is known to up-regulate expression of the progesterone receptor, which, on activation by its ligands, either promotes or inhibits carcinogenesis, depending on the tissue context. Here, we report that progesterone receptor inhibits cervical and vaginal epithelial cell proliferation in a ligand-dependent manner. We also report that synthetic progestin medroxyprogesterone acetate promotes regression of cancers and precancerous lesions in the female lower reproductive tracts (ie, cervix and vagina) in the human papillomavirus transgenic mouse model. Our results provide the first experimental evidence that supports the hypothesis that progesterone signaling is inhibitory for cervical carcinogenesis in vivo.

Uterine glands: development, function and experimental model systems

Development of uterine glands (adenogenesis) in mammals typically begins during the early post-natal period and involves budding of nascent glands from the luminal epithelium and extensive cell proliferation in these structures as they grow into the surrounding stroma, elongate and mature. Uterine glands are essential for pregnancy, as demonstrated by the infertility that results from inhibiting the development of these glands through gene mutation or epigenetic strategies. Several genes, including forkhead box A2, beta-catenin and members of the Wnt and Hox gene families, are implicated in uterine gland development. Progestins inhibit uterine epithelial proliferation, and this has been employed as a strategy to develop a model in which progestin treatment of ewes for 8 weeks from birth produces infertile adults lacking uterine glands. More recently, mouse models have been developed in which neonatal progestin treatment was used to permanently inhibit adenogenesis and adult fertility. These studies revealed a narrow and well-defined window in which progestin treatments induced permanent infertility by impairing neonatal gland development and establishing endometrial changes that result in implantation defects. These model systems are being utilized to better understand the molecular mechanisms underlying uterine adenogenesis and endometrial function. The ability of neonatal progestin treatment in sheep and mice to produce infertility suggests that an approach of this kind may provide a contraceptive strategy with application in other species. Recent studies have defined the temporal patterns of adenogenesis in uteri of neonatal and juvenile dogs and work is underway to determine whether neonatal progestin or other steroid hormone treatments might be a viable contraceptive approach in this species.

Physiological and molecular determinants of embryo implantation

Embryo implantation involves the intimate interaction between an implantation-competent blastocyst and a receptive uterus, which occurs in a limited time period known as the window of implantation. Emerging evidence shows that defects originating during embryo implantation induce ripple effects with adverse consequences on later gestation events, highlighting the significance of this event for pregnancy success. Although a multitude of cellular events and molecular pathways involved in embryo-uterine crosstalk during implantation have been identified through gene expression studies and genetically engineered mouse models, a comprehensive understanding of the nature of embryo implantation is still missing. This review focuses on recent progress with particular attention to physiological and molecular determinants of blastocyst activation, uterine receptivity, blastocyst attachment and uterine decidualization. A better understanding of underlying mechanisms governing embryo implantation should generate new strategies to rectify implantation failure and improve pregnancy rates in women.

Dysregulation of uterine signaling pathways in progesterone receptor-Cre knockout of dicer

Epithelial-stromal interactions in the uterus are required for normal uterine functions such as pregnancy, and multiple signaling pathways are essential for this process. Although Dicer and microRNA (miRNA) have been implicated in several reproductive processes, the specific roles of Dicer and miRNA in uterine development are not known. To address the roles of miRNA in the regulation of key uterine pathways, we generated a conditional knockout of Dicer in the postnatal uterine epithelium and stroma using progesterone receptor-Cre. These Dicer conditional knockout females are sterile with small uteri, which demonstrate significant defects, including absence of glandular epithelium and enhanced stromal apoptosis, beginning at approximately postnatal d 15, with coincident expression of Cre and deletion of Dicer. Specific miRNA (miR-181c, -200b, -101, let-7d) were down-regulated and corresponding predicted proapoptotic target genes (Bcl2l11, Aldh1a3) were up-regulated, reflecting the apoptotic phenomenon. Although these mice had normal serum hormone levels, critical uterine signaling pathways, including progesterone-responsive genes, Indian hedgehog signaling, and the Wnt/β-catenin canonical pathway, were dysregulated at the mRNA level. Importantly, uterine stromal cell proliferation in response to progesterone was absent, whereas uterine epithelial cell proliferation in response to estradiol was maintained in adult uteri. These data implicate Dicer and appropriate miRNA expression as essential players in the regulation of multiple uterine signaling pathways required for uterine development and appropriate function.

The progesterone receptor regulates implantation, decidualization, and glandular development via a complex paracrine signaling network

Many women are affected by infertility and reproductive-associated disease such as endometriosis or endometrial cancer. Successful pregnancy is dependent on a healthy uterus that is fit to receive and support a fertilized embryo. The uterus is an endocrine organ, responsive to the presence of the ovarian steroid hormones, estrogen and progesterone, which activate transcription of target genes through the binding of their cognate receptors, the estrogen receptor and the progesterone receptor. Progesterone signaling has been demonstrated to be critical for the initiation and continuance of pregnancy. Through the induction of Ihh, Wnt, and Bmp pathways within the epithelial and stromal compartments of the uterus, embryo attachment and implantation occur followed by decidualization of the surrounding stroma. Furthermore, these pathways have been shown to be involved in uterine glandular development. This review highlights the integral role of uterine progesterone-mediated paracrine signaling in gland development and pregnancy.

Sex and hedgehog: roles of genes in the hedgehog signaling pathway in mammalian sexual differentiation

The chromosome status of the mammalian embryo initiates a multistage process of sexual development in which the bipotential reproductive system establishes itself as either male or female. These events are governed by intricate cell-cell and interorgan communication that is regulated by multiple signaling pathways. The hedgehog signaling pathway was originally identified for its key role in the development of Drosophila, but is now recognized as a critical developmental regulator in many species, including humans. In addition to its developmental roles, the hedgehog signaling pathway also modulates adult organ function, and misregulation of this pathway often leads to diseases, such as cancer. The hedgehog signaling pathway acts through its morphogenetic ligands that signal from ligand-producing cells to target cells over a specified distance. The target cells then respond in a graded manner based on the concentration of the ligands that they are exposed to. Through this unique mechanism of action, the hedgehog signaling pathway elicits cell fate determination, epithelial-mesenchymal interactions, and cellular homeostasis. Here, we review current findings on the roles of hedgehog signaling in the sexually dimorphic development of the reproductive organs with an emphasis on mammals and comparative evidence in other species.

Progesterone inhibits uterine gland development in the neonatal mouse uterus

Uterine glands and their secretions are required for conceptus (embryo/fetus and associated placenta) survival and development. In most mammals, uterine gland morphogenesis or adenogenesis is a uniquely postnatal event; however, little is known about the mechanisms governing the developmental event. In sheep, progestin treatment of neonatal ewes permanently ablated differentiation of the endometrial glands. Similarly, progesterone (P4) inhibits adenogenesis in neonatal mouse uterus. Thus, P4 can be used as a tool to discover mechanisms regulating endometrial adenogenesis. Female pups were treated with sesame vehicle alone as a control or P4 from Postnatal Day 2 (PD 2) to PD 10, and reproductive tracts were examined on PD 5, 10, or 20. Endometrial glands were fully developed in control mice by PD 20 but not in P4-treated mice. All other uterine cell types appeared normal. Treatment with P4 stimulated proliferation of the stroma but suppressed proliferation of the luminal epithelium. Microarray analysis revealed that expression of genes were reduced (Car2, Fgf7, Fgfr2, Foxa2, Fzd10, Met, Mmp7, Msx1, Msx2, Wnt4, Wnt7a, Wnt16) and increased (Hgf, Ihh, Wnt11) by P4 in the neonatal uterus. These results support the idea that P4 inhibits endometrial adenogenesis in the developing neonatal uterus by altering expression of morphoregulatory genes and consequently disrupting normal patterns of cell proliferation and development.

CDH1 is essential for endometrial differentiation, gland development, and adult function in the mouse uterus

CDH1 is a cell-cell adhesion molecule expressed in the epithelium to coordinate key morphogenetic processes, establish cell polarity, and regulate epithelial differentiation and proliferation. To determine the role of CDH1 in the mouse uterus, Cdh1 was conditionally ablated by crossing Pgr-Cre and Cdh1-flox mice, and the phenotype was characterized. We found that loss of Cdh1 results in a disorganized cellular structure of the epithelium and ablation of endometrial glands in the neonatal uterus. Cdh1(d/d) mice lost adherens junctions (CTNNB1 and CTNNA1) and tight junctions (claudin, occludin, and ZO-1 proteins) in the neonatal uterus, leading to loss of epithelial cell-cell interaction. Ablation of Cdh1 induced abnormal epithelial proliferation and massive apoptosis, and disrupted Wnt and Hox gene expression in the neonatal uterus. Although the uteri of Cdh1(d/d) mice did not show any myometrial defects, ablation of Cdh1 inhibited expression of epithelial (cytokeratin 8) and stromal (CD10) markers. Cdh1(d/d) mice were infertile because of defects during implantation and decidualization. Furthermore, we showed in the model of conditional ablation of both Cdh1 and Trp53 in the uterus that interrupting cell cycle regulation through the loss of Cdh1 leads to abnormal uterine development. The uteri of Cdh1(d/d) Trp53(d/d) mice exhibited histological features of endometrial carcinomas with myometrial invasion. Collectively, these findings suggest that CDH1 has an important role in structural and functional development of the uterus as well as adult uterine function. CDH1 has a capacity to control cell fate by altering directional cell proliferation and apoptosis.

Hedgehog signaling plays roles in epithelial cell proliferation in neonatal mouse uterus and vagina

Both the uterus and vagina develop from the Müllerian duct but are quite distinct in morphology and function. To investigate factors controlling epithelial differentiation and cell proliferation in neonatal uterus and vagina, we focused on Hedgehog (HH) signaling. In neonatal mice, Sonic hh (Shh) was localized in the vaginal epithelium and Indian hh (Ihh) was slightly expressed in the uterus and vagina, whereas all Glioma-associated oncogene homolog (Gli) genes were mainly expressed in the stroma. The expression of target genes of HH signaling was high in the neonatal vagina and in the uterus, it increased with growth. Thus, in neonatal mice, Shh in the vaginal epithelium and Ihh in the uterus and vagina activated HH signaling in the stroma. Tissue recombinants showed that vaginal Shh expression was inhibited by the vaginal stroma and uterine Ihh expression was stimulated by the uterine stroma. Addition of a HH signaling inhibitor decreased epithelial cell proliferation in organ-cultured uterus and vagina and increased stromal cell proliferation in organ-cultured uterus. However, it did not affect epithelial differentiation or the expression of growth factors in organ-cultured uterus and vagina. Thus, activated HH signaling stimulates epithelial cell proliferation in neonatal uterus and vagina but inhibits stromal cell proliferation in neonatal uterus.

Epithelial progesterone receptor exhibits pleiotropic roles in uterine development and function

The ovarian steroid progesterone, acting through the progesterone receptor (PR), coordinates endometrial epithelial-stromal cell communication, which is critical for its development and function. PR expression in these cellular compartments is under tight temporal and endocrine control. Although ex vivo studies demonstrated the importance of stromal PR expression, they failed to show a role for epithelial PR in uterine function. Here, the in vivo role of PR in the uterine epithelium is defined using floxed PR (PR(f/f)) mice crossed to Wnt7a-Cre mice. Progesterone was unable to stimulate the expression of its epithelial target genes, including Ihh, in the Wnt7a-Cre(+)PR(f/-) mice. Analysis was conducted on Ihh to determine whether PR directly regulates epithelial gene transcription. ChIP-on-chip analysis identified PR binding sites in the 5'-flanking region of Ihh. Cotransfection of the proximal Ihh promoter with PR demonstrated that PR directly regulates Ihh transcription. Female Wnt7a-Cre(+)PR(f/-) mice are infertile due to defects in embryo attachment, stromal cell decidualization, and the inability to cease estrogen-induced epithelial cell proliferation. Finally, progesterone was unable to inhibit neonatal endometrial glandular development in Wnt7a-Cre(+)PR(f/-) mice. Thus, epithelial PR is necessary for the regulation of progesterone epithelial target gene expression, as well as uterine function and development.

Permanent oviduct posteriorization after neonatal exposure to the phytoestrogen genistein

BACKGROUND

Preimplantation embryo loss during oviduct transit has been observed in adult mice after a 5-day neonatal exposure to the phytoestrogen genistein (Gen; 50 mg/kg/day).

OBJECTIVE

We investigated the mechanisms underlying the contribution of the oviduct to infertility.

METHODS

Female mice were treated on postnatal days 1-5 with corn oil or Gen (50 mg/kg/day). We compared morphology, gene expression, and protein expression in different regions of the reproductive tracts of Gen-treated mice with those of control littermates at several time points.

RESULTS

Neonatal Gen treatment resulted in substantial changes in expression of genes that modulate neonatal oviduct morphogenesis, including Hoxa (homeobox A cluster), Wnt (wingless-related MMTV integration site), and hedgehog signaling genes. An estrogen receptor antagonist blocked these effects, indicating that they were induced by the estrogenic activity of Gen. Oviducts of adults treated neonatally with Gen had abnormal morphology and were stably "posteriorized," as indicated by altered Hoxa gene patterning during the time of treatment and dramatic, permanent up-regulation of homeobox genes (e.g., Pitx1, Six1) normally expressed only in the cervix and vagina.

CONCLUSIONS

Neonatal exposure to estrogenic environmental chemicals permanently disrupts oviduct morphogenesis and adult gene expression patterns, and these changes likely contribute to the infertility phenotype.

Dominant activation of the hedgehog signaling pathway alters development of the female reproductive tract

The role of hedgehog (HH) signaling in reproductive tract development was studied in mice in which a dominant active allele of the signal transducer smoothened (SmoM2) was conditionally expressed in the Müllerian duct and ovary. Mutant females are infertile, primarily because they fail to ovulate. Levels of mRNA for targets of HH signaling, Gli1, Ptch1, and Hhip, were elevated in reproductive tracts of 24-day-old mutant mice, confirming overactivation of HH signaling. The tracts of mutant mice developed abnormally. The uterine luminal epithelium had a simple columnar morphology in control mice, but in mutants contained stratified squamous cells typical of the cervix and vagina. In mutant mice, the number of uterine glands were reduced and the oviducts were not coiled. Expression of genes within the Hox and Wnt families that regulate patterning of the reproductive tract were altered. Hoxa13, which is normally expressed primarily in the vagina and cervix, was expressed at 12-fold higher levels in the uterus of mutant mice compared with controls. Wnt5a, which is required for development of the cervix and vagina and postnatal differentiation of the uterus, was expressed at higher levels in the oviduct and uterus of mutant mice compared with controls. Mating mutant females with fertile or vasectomized males induced a severe inflammatory response in the tract. In summary, overactivation of HH signaling causes aberrant development of the reproductive tract. The phenotype observed could be mediated by ectopic expression of Hoxa13 in the uterus and elevated levels of Wnt5a in the oviducts and uterus.

Sonic hedgehog supplementation of oocyte and embryo culture media enhances development of IVF porcine embryos

We investigated the expression of sonic hedgehog (SHH) receptor PTCH1 and its co-receptor smoothened (SMO) in fertilized porcine embryos. Effects of exogenous SHH on embryonic development and expressions of survival- and pluripotency-related genes were also determined. We found that PTCH1 and SMO are expressed from two-cell to blastocyst embryos. When oocytes or fertilized embryos were respectively cultured in the maturation or embryo culture medium supplemented with SHH (0.5 μg/ml), their blastocyst rates and total cell numbers increased (P<0.05) compared with the untreated control. When cultured simultaneously in thein vitromaturation (IVM) andin vitroculture (IVC) media supplemented with SHH, the oocytes gained increased blastocyst rates and total cell numbers in an additive manner, with reduced apoptotic indices (P<0.05). Interestingly, SHH treatment did not affect the expression of theBCL2L1(BCL-XL) gene, yet reducedBAXexpression. Blastocysts cultured with various SHH regimes had similar pluripotency-related gene (POU5F1(OCT-4) andCDX2) expression levels, but blastocysts derived from SHH treatment during IVM had higherZPF42(REX01) expression (P<0.05). The highestZPF42expression was observed in the blastocysts derived from SHH-supplemented IVC and from dual IVM and IVC treatments. The levels of acetylated histone 3 (AcH3K9/K14) increased in the two-cell and the four-cell embryos when IVM and/or IVC media were supplemented with SHH (P<0.05). Our findings indicate that SHH conferred a beneficial effect on preimplantation development of porcine embryos, particularly when both IVM and IVC media were supplemented with SHH, and the effects may be further carried over from IVM to the subsequent embryonic development.

WNTs in the neonatal mouse uterus: potential regulation of endometrial gland development

The WNTs are secreted proteins that control essential developmental processes, such as embryonic patterning, cell growth, migration, and differentiation. In mice, three members of the Wnt gene family (Wnt4, Wnt5a, and Wnt7a) have been studied extensively in the female reproductive tract. The present study determined effects of postnatal day and exposure to diethylstilbestrol (DES) on Wnt and Fzd gene expression in the mouse uterus as well as the biological role of Wnt11 in postnatal mouse uterine development and function. Wnt4, Wnt5a, Wnt7a, Wnt7b, Wnt11, Wnt16, Fzd6, and Fzd10 were detected by in situ hybridization in the neonatal mouse uterus. In situ hybridization analyses revealed that Wnt4, Wnt5a, and Wnt16 were localized in the endometrial stroma, whereas Wnt7a, Wnt7b, Wnt11, Fzd6, and Fzd10 were in the uterine epithelia of neonatal mice. Exposure of mice to estrogen or estrogen receptor agonists during critical development periods inhibits endometrial adenogenesis. In the present study, DES-induced disruption of endometrial gland development was associated with reduction or suppression of Wnt4, Wnt5a, Wnt7a, Wnt11, Wnt16, and Fzd10. Ablation of Wnt11, an epithelial-expressed, DES-regulated gene, in the neonatal uterus did not affect endometrial adenogenesis or expression of other Wnt genes. Interestingly, Wnt11-deleted uteri had more endometrial glands on Postnatal Day 10. Although CTNNB1 expression was not affected by ablation of Wnt11, Vangl2 was inhibited in the uteri of Wnt11(d/d) mice. These results support the idea that a number of different Wnt genes are potential regulators for uterine morphogenesis; however, Wnt11 does not have a direct effect on uterine development.