Hoxa11 regulates stromal cell death and proliferation during neonatal uterine development

Role of HOXA10 in pathologies of the endometrium

HOXA10 belongs to the homeobox gene family and is essential for uterine biogenesis, endometrial receptivity, embryo implantation, and stromal cell decidualization. Available evidence suggests that the expression of HOXA10 is dysregulated in different endometrial disorders like endometrial hyperplasia, endometrial cancer, adenomyosis, endometriosis, recurrent implantation failure, and unexplained infertility. The downregulation of HOXA10 occurs by genetic changes in the HOXA10 gene, methylation of the HOXA10 locus, or selected miRNAs. Endocrine disruptors and organic pollutants also cause the reduced expression of HOXA10 in these conditions. In vivo experiments in mouse models and in vitro studies in human cell lines demonstrate that downregulation of HOXA10 leads to endometrial epithelial cell proliferation, failure of stromal cell decidualization, altered expression of genes involved in cell cycle regulation, immunomodulation, and various signaling pathways. These disruptions are speculated to cause infertility associated with the disorders of the endometrium.

Stem cell transcriptional profiles from mouse subspecies reveal cis-regulatory evolution at translation genes

A key goal of evolutionary genomics is to harness molecular data to draw inferences about selective forces that have acted on genomes. The field progresses in large part through the development of advanced molecular-evolution analysis methods. Here we explored the intersection between classical sequence-based tests for selection and an empirical expression-based approach, using stem cells from Mus musculus subspecies as a model. Using a test of directional, cis-regulatory evolution across genes in pathways, we discovered a unique program of induction of translation genes in stem cells of the Southeast Asian mouse M. m. castaneus relative to its sister taxa. We then mined population-genomic sequences to pursue underlying regulatory mechanisms for this expression divergence, finding robust evidence for alleles unique to M. m. castaneus at the upstream regions of the translation genes. We interpret our data under a model of changes in lineage-specific pressures across Mus musculus in stem cells with high translational capacity. Our findings underscore the rigor of integrating expression and sequence-based methods to generate hypotheses about evolutionary events from long ago.

Beclin-1-dependent autophagy, but not apoptosis, is critical for stem-cell-mediated endometrial programming and the establishment of pregnancy

The human endometrium shows a remarkable regenerative capacity that enables cyclical regeneration and remodeling throughout a woman's reproductive life. Although early postnatal uterine developmental cues direct this regeneration, the vital factors that govern early endometrial programming are largely unknown. We report that Beclin-1, an essential autophagy-associated protein, plays an integral role in uterine morphogenesis during the early postnatal period. We show that conditional depletion of Beclin-1 in the uterus triggers apoptosis and causes progressive loss of Lgr5+/Aldh1a1+ endometrial progenitor stem cells, with concomitant loss of Wnt signaling, which is crucial for stem cell renewal and epithelial gland development. Beclin-1 knockin (Becn1 KI) mice with disabled apoptosis exhibit normal uterine development. Importantly, the restoration of Beclin-1-driven autophagy, but not apoptosis, promotes normal uterine adenogenesis and morphogenesis. Together, the data suggest that Beclin-1-mediated autophagy acts as a molecular switch that governs the early uterine morphogenetic program by maintaining the endometrial progenitor stem cells.

The Embryological Landscape of Mayer-Rokitansky-Kuster-Hauser Syndrome: Genetics and Environmental Factors

Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome is a disorder caused by Müllerian ducts dysgenesis affecting 1 in 5000 women with a typical 46,XX karyotype. The etiology of MRKH syndrome is complex and largely unexplained. Familial clustering suggests a genetic component and the spectrum of clinical presentations seems consistent with an inheritance pattern characterized by incomplete penetrance and variable expressivity. Mutations of several candidate genes have been proposed as possible causes based on genetic analyses of human patients and animal models. In addition, studies of monozygotic twins with discordant phenotypes suggest a role for epigenetic changes following potential exposure to environmental compounds. The spectrum of clinical presentations is consistent with intricate disruptions of shared developmental pathways or signals during early organogenesis. However, the lack of functional validation and translational studies have limited our understanding of the molecular mechanisms involved in this condition. The clinical management of affected women, including early diagnosis, genetic testing of MRKH syndrome, and the implementation of counseling strategies, is significantly impeded by these knowledge gaps. Here, we illustrate the embryonic development of tissues and organs affected by MRKH syndrome, highlighting key pathways that could be involved in its pathogenesis. In addition, we will explore the genetics of this condition, as well as the potential role of environmental factors, and discuss their implications to clinical practice.

Regulation of p27 and Cdk2 Expression in Different Adipose Tissue Depots in Aging and Obesity

Aging usually comes associated with increased visceral fat accumulation, reaching even an obesity state, and favoring its associated comorbidities. One of the processes involved in aging is cellular senescence, which is highly dependent on the activity of the regulators of the cell cycle. The aim of this study was to analyze the changes in the expression of p27 and cdk2 in different adipose tissue depots during aging, as well as their regulation by obesity in mice. Changes in the expression of p27 and CDK2 in visceral and subcutaneous white adipose tissue (WAT) biopsies were also analyzed in a human cohort of obesity and type 2 diabetes. p27, but not cdk2, exhibits a lower expression in subcutaneous than in visceral WAT in mice and humans. p27 is drastically downregulated by aging in subcutaneous WAT (scWAT), but not in gonadal WAT, of female mice. Obesity upregulates p27 and cdk2 expression in scWAT, but not in other fat depots of aged mice. In humans, a significant upregulation of p27 was observed in visceral WAT of subjects with obesity. Taken together, these results show a differential adipose depot-dependent regulation of p27 and cdk2 in aging and obesity, suggesting that p27 and cdk2 could contribute to the adipose-tissue depot’s metabolic differences. Further studies are necessary to fully corroborate this hypothesis.

Adult bone marrow progenitors become decidual cells and contribute to embryo implantation and pregnancy

Decidua is a transient uterine tissue shared by mammals with hemochorial placenta and is essential for pregnancy. The decidua is infiltrated by many immune cells promoting pregnancy. Adult bone marrow (BM)-derived cells (BMDCs) differentiate into rare populations of nonhematopoietic endometrial cells in the uterus. However, whether adult BMDCs become nonhematopoietic decidual cells and contribute functionally to pregnancy is unknown. Here, we show that pregnancy mobilizes mesenchymal stem cells (MSCs) to the circulation and that pregnancy induces considerable adult BMDCs recruitment to decidua, where some differentiate into nonhematopoietic prolactin-expressing decidual cells. To explore the functional importance of nonhematopoietic BMDCs to pregnancy, we used Homeobox a11 (Hoxa11)-deficient mice, having endometrial stromal-specific defects precluding decidualization and successful pregnancy. Hoxa11 expression in BM is restricted to nonhematopoietic cells. BM transplant (BMT) from wild-type (WT) to Hoxa11-/- mice results in stromal expansion, gland formation, and marked decidualization otherwise absent in Hoxa11-/- mice. Moreover, in Hoxa11+/- mice, which have increased pregnancy losses, BMT from WT donors leads to normalized uterine expression of numerous decidualization-related genes and rescue of pregnancy loss. Collectively, these findings reveal that adult BMDCs have a previously unrecognized nonhematopoietic physiologic contribution to decidual stroma, thereby playing important roles in decidualization and pregnancy.

A novel mutation of HOXA11 in a patient with septate uterus

BACKGROUND

The etiology of Müllerian duct anomalies (MDAs) is poorly understood at present. The HOXA11 gene is crucial for the development of the Müllerian duct. The objective of this study is to report a unique case of MDAs with a novel mutation in HOXA11.

RESULTS

We identified a potential disease-causing mutation (p. E255K) in a patient with a septate uterus. The mutation was not detected in 169 control subjects or listed in any databases of variations. Bioinformatic predictions and functional studies showed that the mutation reduces the DNA binding affinity and disrupts transactivation ability of HOXA11.

CONCLUSION

In conclusion, this is the first report to describe a HOXA11 mutation in Chinese women with MDAs. The results demonstrated that mutation in HOXA11 can contribute to the etiology of MDAs, especially the septate uterus, but might not be a common cause.

Recurrent Pregnancy Loss: Generally Accepted Causes and Their Management

Recurrent pregnancy loss (RPL), commonly defined as 3 consecutive losses <10 weeks gestation, affects up to 5% of couples. Well-accepted causes include uterine malformation, antiphospholipid syndrome, and parental chromosomal abnormalities; however, the majority of RPL cases are idiopathic (up to 75%). This chapter covers these accepted causes of RPL and provides diagnosis and management strategies for patients falling within the above categories.

Molecular mechanisms of development of the human fetal female reproductive tract

Human female reproductive tract development rests mostly upon hematoxilyn and eosin stained sections despite recent advances on molecular mechanisms in mouse studies. We report application of immunohistochemical methods to explore the ontogeny of epithelial and mesenchymal differentiation markers (keratins, homobox proteins, steroid receptors), transcription factors and signaling molecules (TP63 and RUNX1) during human female reproductive tract development. Keratins 6, 7, 8, 10, 14 and 19 (KRT6, KRT7, KRT8, KRT10, KRT14, KRT19) were expressed in a temporally and spatially dynamic fashion. The undifferentiated Müllerian duct and uterovaginal canal, lined by simple columnar epithelia, expressed KRT7, KRT8 and KRT19. Glandular derivatives of the Müllerian duct (uterine tube, uterine corpus and endocervix) maintained expression of these keratins, while tissues that undergo stratified squamous differentiation (exocervix and vagina) expressed KRT6, KRT14 and KRT10 during development in an age-dependent fashion. TP63 and RUNX1 were expressed prior to KRT14, as these two transcription factors are known to be upstream from KRT14 in developing Müllerian epithelium. In the vagina, KRT10, a marker of terminal differentiation, appeared after endogenous estrogens transformed the epithelium to a thick glycogenated squamous epithelium. Uroplakin, a protein unique to urothelium, was expressed only in the bladder, urethra and vaginal introitus, but not in the female reproductive tract itself. Mesenchymal differentiation was examined through immunostaining for HOXA11 (expressed in uterine mesenchyme) and ISL1 (expressed in vaginal mesenchyme). A detailed ontogeny of estrogen receptor alpha (ESR1), progesterone receptor (PGR) and the androgen receptor (AR) provides the mechanistic underpinning for the teratogenicity of estrogens, progestins and androgens on female reproductive tract development. Immunohistochemical analysis of differentiation markers and signaling molecules advance our understanding of normal development of the human female reproductive tract. These observations demonstrate remarkable similarities in mouse and human female reproductive tract development, but also highlight some key differences.

Characteristic Changes in Decidual Gene Expression Signature in Spontaneous Term Parturition

Background

The decidua has been implicated in the “terminal pathway” of human term parturition, which is characterized by the activation of pro-inflammatory pathways in gestational tissues. However, the transcriptomic changes in the decidua leading to terminal pathway activation have not been systematically explored. This study aimed to compare the decidual expression of developmental signaling and inflammation-related genes before and after spontaneous term labor in order to reveal their involvement in this process.

Methods

Chorioamniotic membranes were obtained from normal pregnant women who delivered at term with spontaneous labor (TIL, n = 14) or without labor (TNL, n = 15). Decidual cells were isolated from snap-frozen chorioamniotic membranes with laser microdissection. The expression of 46 genes involved in decidual development, sex steroid and prostaglandin signaling, as well as pro- and anti-inflammatory pathways, was analyzed using high-throughput quantitative real-time polymerase chain reaction (qRT-PCR). Chorioamniotic membrane sections were immunostained and then semi-quantified for five proteins, and immunoassays for three chemokines were performed on maternal plasma samples.

Results

The genes with the highest expression in the decidua at term gestation included insulin-like growth factor-binding protein 1 (IGFBP1), galectin-1 (LGALS1), and progestogen-associated endometrial protein (PAEP); the expression of estrogen receptor 1 (ESR1), homeobox A11 (HOXA11), interleukin 1β (IL1B), IL8, progesterone receptor membrane component 2 (PGRMC2), and prostaglandin E synthase (PTGES) was higher in TIL than in TNL cases; the expression of chemokine C-C motif ligand 2 (CCL2), CCL5, LGALS1, LGALS3, and PAEP was lower in TIL than in TNL cases; immunostaining confirmed qRT-PCR data for IL-8, CCL2, galectin-1, galectin-3, and PAEP; and no correlations between the decidual gene expression and the maternal plasma protein concentrations of CCL2, CCL5, and IL-8 were found.

Conclusions

Our data suggests that with the initiation of parturition, the decidual expression of anti-inflammatory mediators decreases, while the expression of pro-inflammatory mediators and steroid receptors increases. This shift may affect downstream signaling pathways that can lead to parturition.

Candidate gene analysis in a case of congenital absence of the endometrium

Background

Primary amenorrhea usually result from a genetic or anatomic abnormality. We present the first reported patient with the absence of endometrium and lumen in a small bicornuate uterus in a patient with primary amenorrhea.

Case presentation

A 41-year-old woman presented for evaluation of primary amenorrhea and infertility. She did develop normal secondary sexual characteristics but never had menses. Physical examination, hormone analyses, and karyotype analysis were normal. Transvaginal ultrasonography revealed a small uterus with absent endometrial stripe. Ovaries were normal in size. Pathology from hysterectomy for abnormal Pap smears revealed a hypoplastic bicornuate uterus with absence of lumen and absent endometrium. DNA analyses for mutations in the coding sequences of three members of HOXA gene family was performed, but no variants in the coding sequence of these genes were found. These findings support the hypothesis that mutations in the coding sequence of HOXA10, HOXA11, and HOXA13 are not responsible for congenital endometrial absence with bicornuate hypoplastic uterus.

Conclusions

Congenital absence of the endometrium is an uncommon etiology for primary amenorrhea, and nonvisualization of the endometrial stripe on ultrasound imaging in association with primary amenorrhea should raise suspicion of this rare disorder in this case.

Regulation of endometrial receptivity by the highly expressed HOXA9, HOXA11 and HOXD10 HOX-class homeobox genes

STUDY QUESTION

Are other HOX genes, in addition to HOXA10, involved in endometrial receptivity?

SUMMARY ANSWER

The highly expressed HOXA9, HOXA11 and HOXD10 genes also appear to be involved in endometrial receptivity.

WHAT IS KNOWN ALREADY

Within the HOX family of homeobox transcription factor genes are the leading candidates for the regulation of embryonic implantation. A crucial role of HOXA10 in endometrial receptivity has been well established.

STUDY DESIGN, SIZE, DURATION

To identify HOX candidate genes, we performed data mining on all 39 human HOX genes in the 'Human body index' gene expression database of normal human tissue. The temporal and spatial expression pattern of four highly expressed HOX genes in the human endometrium was determined. To further investigate the function of these Hox genes, we used a robust in vivo mouse model in which we blocked maternal Hox gene expression.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

Analysis of a gene expression profile set in the public domain consisting of 504 samples representing 95 different normal human tissues, showed that in addition to HOXA10, also HOXA9, HOXA11, HOXB6 and HOXD10 mRNA showed increased expression in the human endometrium (16 samples). The temporal and spatial expression pattern of these four HOX genes throughout the menstrual cycle was determined in the endometrium from 27 female patients eligible for IVF-embryo transfer with a normal cycle by quantitative real-time PCR (qRT-PCR), western blot and immunohistochemistry. The role of maternal Hoxa9, Hoxa11 and Hoxd10 was assessed in a mouse implantation model by expression knockdown using RNA interference. Forty mice were transfected with Hoxa9-, Hoxa11- or Hoxd10-specific small hairpin RNA (shRNA) constructs or a vector control by injection into the uterine horn at Day 2 after vaginal plug detection (Day 1) (160 mice in total). The effects were examined by qRT-PCR and western blot at Day 4 and litter sizes counted at Day 9 of pregnancy.

MAIN RESULTS AND THE ROLE OF CHANCE

HOXA10, HOXA9, HOXA11 and HOXD10 all showed increased expression during the mid-secretory phase of the menstrual cycle (P < 0.01). Knockdown of Hoxa9, Hoxa11 and Hoxd10 in the murine uterus resulted in significantly reduced average implantation rates (P < 0.01) and, with regard to four Hox target genes, also correlated with a significantly increased empty spiracles homolog 2 (Emx2) and insulin-like growth factor binding protein-1 (Igfbp1), and decreased integrin β3 (Itgb3) and leukemia inhibitory factor (Lif), expression (P < 0.01).

LIMITATIONS, REASONS FOR CAUTION

Menstrual cycle stage was not confirmed by serum hormone analysis. We verified the absence of significant differences in stage-specific expression of the reference genes used in our study (ACTB/Actb and GAPDH/Gapdh) and therefore possible limitations of this approach were minimized. In addition, the translatability of our data from a mouse model to patients needs to be investigated further.

WIDER IMPLICATIONS OF THE FINDINGS

We provide evidence that three other HOX genes in addition to HOXA10 are involved in endometrial receptivity, and that part of their function is asserted through several known HOX target genes, suggesting the presence of a central HOX signal transduction pathway.

Immunohistochemical studies on the proliferative marker Ki-67 and estrogen receptor alpha (ERα) in the uterus of neonatal and immature pigs following exposure to flutamide

The development of uterine glands is characterized by the proliferation of epithelial cells and by estrogen receptor alpha (ERα) expression in the nascent glandular epithelium. It is known that androgen receptors are present in the porcine uterus during prenatal development and the neonatal window, when adenogenesis occurs. Therefore, the objective of the study was to determine whether the effects of maternal or neonatal administration of the anti-androgen, flutamide, could entail changes in the presence of ERα and proliferation of uterine cells in neonatal and three-month-old pigs. Following prenatal flutamide exposure, morphological differences and the acceleration of uterus differentiation marked by ERα expression in epithelial crypts were observed in the neonatal piglets. In the three-month-old pig uterus, the proliferation of stromal cells was observed only after prenatal exposure to flutamide, whereas ERα staining was weaker. The neonatal administration of flutamide caused a significant decrease in the proliferation of the surface epithelium and diminished intensity of ERα staining in the stromal cells of the uterus of three-month-old pigs, which paralleled decreased estrogen levels in these animals. Overall, prenatal flutamide exposure promoted growth and development of the neonatal porcine uterus. Moreover, in three-month-old pigs, flutamide application during the neonatal period decreased surface epithelium proliferation and stromal ERα expression, which confirmed the importance of epithelial-stromal interactions in the adenogenesis.

Postnatal deletion of Wnt7a inhibits uterine gland morphogenesis and compromises adult fertility in mice

The success of postnatal uterine morphogenesis dictates, in part, the embryotrophic potential and functional capacity of the adult uterus. The definitive role of Wnt7a in postnatal uterine development and adult function requires a conditional knockout, because global deletion disrupts müllerian duct patterning, specification, and cell fate in the fetus. The Wnt7a-null uterus appears to be posteriorized because of developmental defects in the embryo, as evidenced by the stratified luminal epithelium that is normally found in the vagina and the presence of short and uncoiled oviducts. To understand the biological role of WNT7A after birth and allow tissue-selective deletion of Wnt7a, we generated loxP-flanked exon 2 mice and conditionally deleted Wnt7a after birth in the uterus by crossing them with Pgr(Cre) mice. Morphological examination revealed no obvious differences in the vagina, cervix, oviduct, or ovary. The uteri of Wnt7a mutant mice contained no endometrial glands, whereas all other uterine cell types appeared to be normal. Postnatal differentiation of endometrial glands was observed in control mice, but not in mutant mice, between Postnatal Days 3 and 12. Expression of morphoregulatory genes, particularly Foxa2, Hoxa10, Hoxa11, Msx1, and Wnt16, was disrupted in the Wnt7a mutant uteri. Conditional Wnt7a mutant mice were not fertile. Although embryos were present in uteri of mutant mice on Day 3.5 of pregnancy, blastocyst implantation was not observed on Day 5.5. Furthermore, expression of several genes (Foxa2, Lif, Msx1, and Wnt16) was reduced or absent in adult Wnt7a-deleted uteri on Day 3.5 postmating. These results indicate that WNT7A plays a critical role in postnatal uterine gland morphogenesis and function, which are important for blastocyst implantation and fertility in the adult uterus.

Generation and expression of a Hoxa11eGFP targeted allele in mice

Hox genes are crucial for body axis specification during embryonic development. Hoxa11 plays a role in anteroposterior patterning of the axial skeleton, development of the urogenital tract of both sexes, and proximodistal patterning of the limbs. Hoxa11 expression is also observed in the neural tube. Herein, we report the generation of a Hoxa11eGFP targeted knock-in allele in mice in which eGFP replaces the first coding exon of Hoxa11 as an in-frame fusion. This allele closely recapitulates the reported mRNA expression patterns for Hoxa11. Hoxa11eGFP can be visualized in the tail, neural tube, limbs, kidneys, and reproductive tract of both sexes. Additionally, homozygous mutants recapitulate reported phenotypes for Hoxa11 loss of function mice, exhibiting loss of fertility in both males and females. This targeted mouse line will prove useful as a vital marker for Hoxa11 protein localization during control (heterozygous) or mutant organogenesis.

Adaptive changes in the transcription factor HoxA-11 are essential for the evolution of pregnancy in mammals

Evolutionary change in gene regulation can result from changes in cis-regulatory elements, leading to differences in the temporal and spatial expression of genes or in the coding region of transcription factors leading to novel functions or both. Although there is a growing body of evidence supporting the importance of cis-regulatory evolution, examples of protein-mediated evolution of novel developmental pathways have not been demonstrated. Here, we investigate the evolution of prolactin (PRL) expression in endometrial cells, which is essential for placentation/pregnancy in eutherian mammals and is a direct regulatory target of the transcription factor HoxA-11. Here, we show that (i) endometrial PRL expression is a derived feature of placental mammals, (ii) the PRL regulatory gene HoxA-11 experienced a period of strong positive selection in the stem-lineage of eutherian mammals, and (iii) only HoxA-11 proteins from placental mammals, including the reconstructed ancestral eutherian gene, are able to up-regulate PRL from the promoter used in endometrial cells. In contrast, HoxA-11 from the reconstructed therian ancestor, opossum, platypus, and chicken are unable to up-regulate PRL expression. These results demonstrate that the evolution of novel gene expression domains is not only mediated by the evolution of cis-regulatory elements but can also require evolutionary changes of transcription factor proteins themselves.

MMTV-EGF receptor transgene promotes preneoplastic conversion of multiple steroid hormone-responsive tissues

Correlative analyses of tumors and patient-derived cell lines of the human reproductive system suggest that overexpression of EGF contributes to the oncogenic phenotype. However, it is unclear at what stage in disease overexpression of the EGFR is most critical. To assess its role as an initiator of reproductive tissue tumor development, transgenic mice were derived with mouse mammary tumor virus (MMTV)-regulated overexpression of the human EGFR. Although elevated expression of the EGFR in hormonally responsive tissues was observed, only one EGFR transgenic mouse developed a visible tumor over a 2-year period. However, of 12 females monitored over the same time, hyperplasia, hypertrophy, or slight dysplasia was found in mammary glands of 55% of the animals examined, in the uterus or uterine horn of 89%, and in ovaries or oviducts of 100%. None of the reproductive tissues of the male transgenic animals or age-matched, normal mice displayed these changes. These results revealed a role for the EGFR in the initiation of ovarian and uterine cancer and supported previous studies in breast cancer that the receptor can contribute to the neoplastic process in a significant albeit incremental way.

Neonatal estrogenic exposure suppresses PTEN-related endometrial carcinogenesis in recombinant mice

Human endometrial carcinomas, as well as complex atypical hyperplasias (CAH), are estrogen related and frequently have mutations in the PTEN gene. However, the mutual contribution of estrogen and PTEN mutations to endometrial carcinogenesis in vivo is unknown. To address this issue, we investigated whether neonatal estrogenic treatments augment the incidence of CAH and carcinomas in murine PTEN (mPTEN) heterozygous (+/-) mutant mice, an animal model for endometrial carcinoma. Low doses of diethylstilbestrol (1 ng/g/day), genistein (50 microg/g/day) in phytoestrogens, estriol (E(3)) (4 microg/g/day), and vehicle (ethanol and corn oil) were administered subcutaneously daily to neonatal pups from the 1st to 5th day after birth. At 52 weeks of age, the morphological changes in the endometrium, and uterine expression of Hoxa 10 and Hoxa 11, were evaluated. These Hoxa genes are abdominal B-type homeobox genes, which normally regulate differentiation of the Müllerian duct. The incidence of CAH and adenocarcinomas of the endometrium was significantly decreased by the neonatal estrogenic treatments in the mPTEN+/- mice. Coincidentally, all treatments significantly decreased the stromal cell density, and CAH and adenocarcinomas rarely developed in the epithelium adjacent to the affected endometrial stroma. Moreover, the uterine expression of Hoxa 10 in mice with neonatal genistein and E(3) treatments, and that of Hoxa 11 in mice with all treatments, was significantly lower when compared with vehicle alone. Taken together, neonatal estrogenic exposure induced stromal atrophy and/or hyalinization accompanied by repressed expression of Hoxa 10 and Hoxa 11, and exerted an inhibitory effect on PTEN-related tumorigenesis. These findings provide new insight into the interaction between endometrial epithelium and stroma in endometrial carcinogenesis in vivo.

Subfertility, Uterine Hypoplasia, and Partial Progesterone Resistance in Mice Lacking the Krüppel-like Factor 9/Basic Transcription Element-binding Protein-1 (Bteb1) Gene

Progesterone receptor (PR), a ligand-activated transcription factor, is a key regulator of cellular proliferation and differentiation in reproductive tissues. The transcriptional activity of PR is influenced by co-regulatory proteins typically expressed in a tissue- and cell-specific fashion. We previously demonstrated that basic transcription element-binding protein-1 (BTEB1), a member of the Sp/Krüppel-like family of transcription factors, functionally interacts with the two PR isoforms, PR-A and PR-B, to mediate progestin sensitivity of target genes in endometrial epithelial cells in vitro. Here we report that ablation of the Bteb1 gene in female mice results in uterine hypoplasia, reduced litter size, and increased incidence of neonatal deaths in offspring. The reduced litter size is solely a maternal genotype effect and results from fewer numbers of implantation sites, rather than defects in ovulation. In the early pregnant uterus, Bteb1 expression in stromal cells temporally coincides with PR-A isoform-dependent decidual formation at the time of implantation. Expression of two implantation-specific genes, Hoxa10 and cyclin D3, was decreased in uteri of early pregnant Bteb1-null mutants, whereas that of Bteb3, a related family member, was increased, the latter possibly compensating for the loss of Bteb1. Progesterone responsiveness of several uterine genes was altered with Bteb1-null mutation. These results identify Bteb1 as a functionally relevant PR-interacting protein and suggest its selective modulation of cellular processes that are regulated by PR-A in the uterine stroma.

Uterine Msx-1 and Wnt4 Signaling Becomes Aberrant in Mice with the Loss of Leukemia Inhibitory Factor or Hoxa-10: Evidence for a Novel Cytokine-Homeobox-Wnt Signaling in Implantation

Successful implantation absolutely depends on the reciprocal interaction between the implantation-competent blastocyst and the receptive uterus. Expression and gene targeting studies have shown that leukemia inhibitory factor (LIF), a cytokine of the IL-6 family, and Hoxa-10, an abdominalB-like homeobox gene, are crucial to implantation and decidualization in mice. Using these mutant mice, we sought to determine the importance of Msx-1 (another homeobox gene formerly known as Hox-7.1) and of Wnt4 (a ligand of the Wnt family) signaling in implantation because of their reported functions during development. We observed that Msx-1, Wnt4, and a Wnt antagonist sFRP4 are differentially expressed in the mouse uterus during the periimplantation period, suggesting their role in implantation. In addition, we observed an aberrant uterine expression of Msx-1 and sFRP4 in Lif mutant mice, and of Wnt4 and sFRP4 in Hoxa-10 mutant mice, further reinforcing the importance of these signaling pathways in implantation. Collectively, the present results provide evidence for a novel cytokine-homeotic-Wnt signaling network in implantation.