An oocyte-specific Cas9-expressing mouse for germline CRISPR/Cas9-mediated genome editing

Cas9 transgenes can be employed for genome editing in mouse zygotes. However, using transgenic instead of exogenous Cas9 to produce gene-edited animals creates unique issues including ill-defined transgene integration sites, the potential for prolonged Cas9 expression in transgenic embryos, and increased genotyping burden. To overcome these issues, we generated mice harboring an oocyte-specific, Gdf9 promoter driven, Cas9 transgene (Gdf9-Cas9) targeted as a single copy into the Hprt1 locus. The X-linked Hprt1 locus was selected because it is a defined integration site that does not influence transgene expression, and breeding of transgenic males generates obligate transgenic females to serve as embryo donors. Using microinjections and electroporation to introduce sgRNAs into zygotes derived from transgenic dams, we demonstrate that Gdf9-Cas9 mediates genome editing as efficiently as exogenous Cas9 at several loci. We show that genome editing efficiency is independent of transgene inheritance, verifying that maternally derived Cas9 facilitates genome editing. We also show that paternal inheritance of Gdf9-Cas9 does not mediate genome editing, confirming that Gdf9-Cas9 is not expressed in embryos. Finally, we demonstrate that off-target mutagenesis is equally rare when using transgenic or exogenous Cas9. Together, these results show that the Gdf9-Cas9 transgene is a viable alternative to exogenous Cas9.

Establishment of Murine Pregnancy Requires the Promyelocytic Leukemia Zinc Finger Transcription Factor

Using an established human primary cell culture model, we previously demonstrated that the promyelocytic leukemia zinc finger (PLZF) transcription factor is a direct target of the progesterone receptor (PGR) and is essential for progestin-dependent decidualization of human endometrial stromal cells (HESCs). These in vitro findings were supported by immunohistochemical analysis of human endometrial tissue biopsies, which showed that the strongest immunoreactivity for endometrial PLZF is detected during the progesterone (P4)-dominant secretory phase of the menstrual cycle. While these human studies provided critical clinical support for the important role of PLZF in P4-dependent HESC decidualization, functional validation in vivo was not possible due to the absence of suitable animal models. To address this deficiency, we recently generated a conditional knockout mouse model in which PLZF is ablated in PGR-positive cells of the mouse (Plzf d/d). The Plzf d/d female was phenotypically analyzed using immunoblotting, real-time PCR, and immunohistochemistry. Reproductive function was tested using the timed natural pregnancy model as well as the artificial decidual response assay. Even though ovarian activity is not affected, female Plzf d/d mice exhibit an infertility phenotype due to an inability of the embryo to implant into the Plzf d/d endometrium. Initial cellular and molecular phenotyping investigations reveal that the Plzf d/d endometrium is unable to develop a transient receptive state, which is reflected at the molecular level by a blunted response to P4 exposure with a concomitant unopposed response to 17-β estradiol. In addition to a defect in P4-dependent receptivity, the Plzf d/d endometrium fails to undergo decidualization in response to an artificial decidual stimulus, providing the in vivo validation for our earlier HESC culture findings. Collectively, our new Plzf d/d mouse model underscores the physiological importance of the PLZF transcription factor not only in endometrial stromal cell decidualization but also uterine receptivity, two uterine cellular processes that are indispensable for the establishment of pregnancy.

A GREB1-steroid receptor feedforward mechanism governs differential GREB1 action in endometrial function and endometriosis

Cellular responses to the steroid hormones, estrogen (E2), and progesterone (P4) are governed by their cognate receptor's transcriptional output. However, the feed-forward mechanisms that shape cell-type-specific transcriptional fulcrums for steroid receptors are unidentified. Herein, we found that a common feed-forward mechanism between GREB1 and steroid receptors regulates the differential effect of GREB1 on steroid hormones in a physiological or pathological context. In physiological (receptive) endometrium, GREB1 controls P4-responses in uterine stroma, affecting endometrial receptivity and decidualization, while not affecting E2-mediated epithelial proliferation. Of mechanism, progesterone-induced GREB1 physically interacts with the progesterone receptor, acting as a cofactor in a positive feedback mechanism to regulate P4-responsive genes. Conversely, in endometrial pathology (endometriosis), E2-induced GREB1 modulates E2-dependent gene expression to promote the growth of endometriotic lesions in mice. This differential action of GREB1 exerted by a common feed-forward mechanism with steroid receptors advances our understanding of mechanisms that underlie cell- and tissue-specific steroid hormone actions.

Steroid receptor coactivator-2 drives epithelial reprogramming that enables murine embryo implantation

Although we have shown that steroid receptor coactivator-2 (SRC-2), a member of the p160/SRC family of transcriptional coregulators, is essential for decidualization of both human and murine endometrial stromal cells, SRC-2's role in the earlier stages of the implantation process have not been adequately addressed. Using a conditional SRC-2 knockout mouse (SRC-2d/d ) in timed natural pregnancy studies, we show that endometrial SRC-2 is required for embryo attachment and adherence to the luminal epithelium. Implantation failure is associated with the persistent expression of Mucin 1 and E-cadherin on the apical surface and basolateral adherens junctions of the SRC-2d/d luminal epithelium, respectively. These findings indicate that the SRC-2d/d luminal epithelium fails to exhibit a plasma membrane transformation (PMT) state known to be required for the development of uterine receptivity. Transcriptomics demonstrated that the expression of genes involved in steroid hormone control of uterine receptivity were significantly disrupted in the SRC-2d/d endometrium as well as genes that control epithelial tight junctional biology and the emergence of the epithelial mesenchymal transition state, with the latter sharing similar biological properties with PMT. Collectively, these findings uncover a new role for endometrial SRC-2 in the induction of the luminal epithelial PMT state, which is a prerequisite for the development of uterine receptivity and early pregnancy establishment.

Functional analysis reveals driver cooperativity and novel mechanisms in endometrial carcinogenesis

High-risk endometrial cancer has poor prognosis and is increasing in incidence. However, understanding of the molecular mechanisms which drive this disease is limited. We used genetically engineered mouse models (GEMM) to determine the functional consequences of missense and loss of function mutations in Fbxw7, Pten and Tp53, which collectively occur in nearly 90% of high-risk endometrial cancers. We show that Trp53 deletion and missense mutation cause different phenotypes, with the latter a substantially stronger driver of endometrial carcinogenesis. We also show that Fbxw7 missense mutation does not cause endometrial neoplasia on its own, but potently accelerates carcinogenesis caused by Pten loss or Trp53 missense mutation. By transcriptomic analysis, we identify LEF1 signalling as upregulated in Fbxw7/FBXW7-mutant mouse and human endometrial cancers, and in human isogenic cell lines carrying FBXW7 mutation, and validate LEF1 and the additional Wnt pathway effector TCF7L2 as novel FBXW7 substrates. Our study provides new insights into the biology of high-risk endometrial cancer and suggests that targeting LEF1 may be worthy of investigation in this treatment-resistant cancer subgroup.

From cup to dish: how to make and use endometrial organoid and stromal cultures derived from menstrual fluid

Diseases impacting the female reproductive tract pose a critical health concern. The establishment of in vitro models to study primary endometrial cells is crucial to understanding the mechanisms that contribute to normal endometrial function and the origins of diseases. Established protocols for endometrial stromal cell culture have been in use for decades but recent advances in endometrial organoid culture have paved the way to allowing study of the roles of both epithelial and stromal endometrial cells in vitro. Due to inter-individual variability, primary cell cultures must be established from numerous persons. Generally, endometrial epithelial and stromal cells can be isolated from an endometrial biopsy, however, this is collected in a clinical setting by an invasive transcervical procedure. Our goal was to develop a non-invasive method for the isolation of paired endometrial epithelial organoids and stromal cells from menstrual fluid collected from individual women, based on recent reports describing the isolation of endometrial epithelial organoids or endometrial stromal cells from menstrual fluid. Participants recruited by the NIEHS Clinical Research Unit were provided with a menstrual cup and instructed to collect on the heaviest day of their menstrual period. Endometrial tissue fragments in the menstrual fluid samples were washed to remove blood, minced, and digested with proteinases. Following digestion, the solution was strained to separate epithelial fragments from stromal cells. Epithelial fragments were washed, resuspended in Matrigel, and plated for organoid formation. Stromal cells were separated from residual red blood cells using a Ficoll gradient and then plated in a flask. Once established, estrogen responsiveness of endometrial epithelial organoids was assessed and the decidual response of stromal cells was evaluated. Following treatments, qPCR was performed on organoids for genes induced by estradiol and on stromal cells for genes induced by decidualization. In this manner, the relative responsiveness of paired organoid and stroma cell cultures isolated from each woman could be assessed. In conclusion, we can isolate both epithelial and stromal cells from a single menstrual fluid sample, allowing us to establish organoids and cells in a paired manner. This protocol can greatly enhance our knowledge of the role of epithelial and stromal cells alone and in coordination.

The NR2F2-HAND2 signaling axis regulates progesterone actions in the uterus at early pregnancy

Endometrial function is dependent on a tight crosstalk between the epithelial and stromal cells of the endometrium. This communication is critical to ensure a fertile uterus and relies on progesterone and estrogen signaling to prepare a receptive uterus for embryo implantation in early pregnancy. One of the key mediators of this crosstalk is the orphan nuclear receptor NR2F2, which regulates uterine epithelial receptivity and stromal cell differentiation. In order to determine the molecular mechanism regulated by NR2F2, RNAseq analysis was conducted on the uterus of PgrCre;Nr2f2f/f mice at Day 3.5 of pregnancy. This transcriptomic analysis demonstrated Nr2f2 ablation in Pgr-expressing cells leads to a reduction of Hand2 expression, increased levels of Hand2 downstream effectors Fgf1 and Fgf18, and a transcriptome manifesting suppressed progesterone signaling with an altered immune baseline. ChIPseq analysis conducted on the Day 3.5 pregnant mouse uterus for NR2F2 demonstrated the majority of NR2F2 occupies genomic regions that have H3K27ac and H3K4me1 histone modifications, including the loci of major uterine transcription regulators Hand2, Egr1, and Zbtb16. Furthermore, functional analysis of an NR2F2 occupying site that is conserved between human and mouse was capable to enhance endogenous HAND2 mRNA expression with the CRISPR activator in human endometrial stroma cells. These data establish the NR2F2 dependent regulation of Hand2 in the stroma and identify a cis-acting element for this action. In summary, our findings reveal a role of the NR2F2-HAND2 regulatory axis that determines the uterine transcriptomic pattern in preparation for the endometrial receptivity.

Chromatin architectural factor CTCF is essential for progesterone-dependent uterine maturation

Receptors for estrogen and progesterone frequently interact, via Cohesin/CTCF loop extrusion, at enhancers distal from regulated genes. Loss-of-function CTCF mutation in >20% of human endometrial tumors indicates its importance in uterine homeostasis. To better understand how CTCF-mediated enhancer-gene interactions impact endometrial development and function, the Ctcf gene was selectively deleted in female reproductive tissues of mice. Prepubertal Ctcfd/d uterine tissue exhibited a marked reduction in the number of uterine glands compared to those without Ctcf deletion (Ctcff/f mice). Post-pubertal Ctcfd/d uteri were hypoplastic with significant reduction in both the amount of the endometrial stroma and number of glands. Transcriptional profiling revealed increased expression of stem cell molecules Lif, EOMES, and Lgr5, and enhanced inflammation pathways following Ctcf deletion. Analysis of the response of the uterus to steroid hormone stimulation showed that CTCF deletion affects a subset of progesterone-responsive genes. This finding indicates (1) Progesterone-mediated signaling remains functional following Ctcf deletion and (2) certain progesterone-regulated genes are sensitive to Ctcf deletion, suggesting they depend on gene-enhancer interactions that require CTCF. The progesterone-responsive genes altered by CTCF ablation included Ihh, Fst, and Errfi1. CTCF-dependent progesterone-responsive uterine genes enhance critical processes including anti-tumorigenesis, which is relevant to the known effectiveness of progesterone in inhibiting progression of early-stage endometrial tumors. Overall, our findings reveal that uterine Ctcf plays a key role in progesterone-dependent expression of uterine genes underlying optimal post-pubertal uterine development.

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.

CFP1 governs uterine epigenetic landscapes to intervene in progesterone responses for uterine physiology and suppression of endometriosis

Progesterone (P₄) is required for the preparation of the endometrium for a successful pregnancy. P₄ resistance is a leading cause of the pathogenesis of endometrial disorders like endometriosis, often leading to infertility; however, the underlying epigenetic cause remains unclear. Here we demonstrate that CFP1, a regulator of H3K4me3, is required for maintaining epigenetic landscapes of P₄-progesterone receptor (PGR) signaling networks in the mouse uterus. Cfp1^f/f;Pgr-Cre (Cfp1^d/d) mice showed impaired P₄ responses, leading to complete failure of embryo implantation. mRNA and chromatin immunoprecipitation sequencing analyses showed that CFP1 regulates uterine mRNA profiles not only in H3K4me3-dependent but also in H3K4me3-independent manners. CFP1 directly regulates important P₄ response genes, including Gata2, Sox17, and Ihh, which activate smoothened signaling pathway in the uterus. In a mouse model of endometriosis, Cfp1^d/d ectopic lesions showed P₄ resistance, which was rescued by a smoothened agonist. In human endometriosis, CFP1 was significantly downregulated, and expression levels between CFP1 and these P₄ targets are positively related regardless of PGR levels. In brief, our study provides that CFP1 intervenes in the P₄-epigenome-transcriptome networks for uterine receptivity for embryo implantation and the pathogenesis of endometriosis.

iCre recombinase expressed in the anti-Müllerian hormone receptor 2 gene causes global genetic modification in the mouse†

Genetically engineered mice are widely used to study the impact of altered gene expression in vivo. Within the reproductive tract, the Amhr2-IRES-Cre(Bhr) mouse model is used to ablate genes in ovarian granulosa and uterine stromal cells. There are reports of Amhr2-IRES-Cre(Bhr) inducing recombination in non-target tissues. We hypothesized the inefficiency or off-target Cre action in Amhr2-IRES-Cre(Bhr) mice is due to lack of recombination in every cell that expresses Amhr2. To investigate, we created a new targeted knock-in mouse model, Amhr2-iCre(Fjd), by inserting a codon-optimized improved Cre (iCre) into exon 1 of the Amhr2 gene. Amhr2-iCre(Fjd)/+ males were mated with females that contain a lox-stop-lox cassette in the Sun1 gene so when DNA recombination occurs, SUN1-sfGFP fusion protein is expressed in a peri-nuclear pattern. In adult Amhr2-iCre(Fjd)/+ Sun1LsL/+ mice, Amhr2-iCre(Fjd)-mediated genetic recombination was apparent in uterine epithelial, stromal, and myometrial cells, while Amhr2-IRES-Cre(Bhr)/+ Sun1LsL/+ females demonstrated inter-mouse variability of Amhr2-IRES-Cre(Bhr) activity in uterine cells. Fluorescence was observed in Amhr2-iCre(Fjd)-positive mice at post-natal Day 1, indicating global genetic recombination, while fluorescence of individual Amhr2-IRES-Cre(Bhr)-positive pups varied. To determine the developmental stage that genetic recombination first occurs, Sun1LsL/LsL females were super-ovulated and mated with Amhr2-IRES-Cre(Bhr)/+ or Amhr2(iCre/+)Fjd males, then putative zygotes were collected and cultured. In the four-cell embryo, Amhr2-iCre(Fjd) and Amhr2-IRES-Cre(Bhr) activities were apparent in 100% and 25-100% of cells, respectively. In conclusion, Amhr2-IRES-Cre(Bhr) or Amhr2-iCre(Fjd) driven by the Amhr2 promoter is active in the early embryo and can lead to global genetic modification, rendering this transgenic mouse model ineffective.

Decidualization of human endometrial stromal cells requires steroid receptor coactivator-3

Steroid receptor coactivator-3 (SRC-3; also known as NCOA3 or AIB1) is a member of the multifunctional p160/SRC family of coactivators, which also includes SRC-1 and SRC-2. Clinical and cell-based studies as well as investigations on mice have demonstrated pivotal roles for each SRC in numerous physiological and pathophysiological contexts, underscoring their functional pleiotropy. We previously demonstrated the critical involvement of SRC-2 in murine embryo implantation as well as in human endometrial stromal cell (HESC) decidualization, a cellular transformation process required for trophoblast invasion and ultimately placentation. We show here that, like SRC-2, SRC-3 is expressed in the epithelial and stromal cellular compartments of the human endometrium during the proliferative and secretory phase of the menstrual cycle as well as in cultured HESCs. We also found that SRC-3 depletion in cultured HESCs results in a significant attenuation in the induction of a wide-range of established biomarkers of decidualization, despite exposure of these cells to a deciduogenic stimulus and normal progesterone receptor expression. These molecular findings are supported at the cellular level by the inability of HESCs to morphologically transform from a stromal fibroblastoid cell to an epithelioid decidual cell when endogenous SRC-3 levels are markedly reduced. To identify genes, signaling pathways and networks that are controlled by SRC-3 and potentially important for hormone-dependent decidualization, we performed RNA-sequencing on HESCs in which SRC-3 levels were significantly reduced at the time of administering the deciduogenic stimulus. Comparing HESC controls with HESCs deficient in SRC-3, gene enrichment analysis of the differentially expressed gene set revealed an overrepresentation of genes involved in chromatin remodeling, cell proliferation/motility, and programmed cell death. These predictive bioanalytic results were confirmed by the demonstration that SRC-3 is required for the expansion, migratory and invasive activities of the HESC population, cellular properties that are required in vivo in the formation or functioning of the decidua. Collectively, our results support SRC-3 as an important coregulator in HESC decidualization. Since perturbation of normal homeostatic levels of SRC-3 is linked with common gynecological disorders diagnosed in reproductive age women, this endometrial coregulator-along with its new molecular targets described here-may open novel clinical avenues in the diagnosis and/or treatment of a non-receptive endometrium, particularly in patients presenting non-aneuploid early pregnancy loss.

The single-cell atlas of cultured human endometrial stromal cells

OBJECTIVE

To systematically analyze the cell composition and transcriptome of primary human endometrial stromal cells (HESCs) and transformed human endometrial stromal cells (THESCs).

DESIGN

The primary HESCs from 3 different donors and 1 immortalized THESC were collected from the human endometrium at the midsecretory phase and cultured in vitro.

SETTING

Academic research laboratory.

PATIENT(S)

None.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Single-cell ribonucleic acid sequencing analysis.

RESULT(S)

We found the individual differences among the primary HESCs and bigger changes between the primary HESCs and THESCs. Cell clustering with or without integration identified cell clusters belonging to mature, proliferative, and active fibroblasts that were conserved across all samples at different stages of the cell cycles with intensive cell communication signals. All primary HESCs and THESCs can be correlated with some subpopulations of fibroblasts in the human endometrium.

CONCLUSION(S)

Our study indicated that the primary HESCs and THESCs displayed conserved cell characters and distinct cell clusters. Mature, proliferative, and active fibroblasts at different stages or cell cycles were detected across all samples and presented with a complex cell communication network. The cultured HESCs and THESCs retained the features of some subpopulations within the human endometrium.

The role of progesterone receptor isoforms in the myometrium

Myometrial contraction is stringently controlled throughout pregnancy and parturition. Progesterone signaling, effecting through the progesterone receptor (PR), is pivotal in modulating uterine activity. Evidence has shown that two major PR isoforms, PR-A and PR-B, have distinct activities on gene regulation, and the ratio between these isoforms determines the contractility of the myometrium at different gestational stages. Herein, we focus on the regulation of PR activity in the myometrium, especially the differential actions of the two PR isoforms, which maintain uterine quiescence during pregnancy and regulate the switch to a contractile state at the onset of labor. To demonstrate the PR regulatory network and its mechanisms of actions on myometrial activity, we summarized the findings into three parts: Regulation of PR Expression and Isoform Levels, Progesterone Receptor Interacting Factors, and Biological Processes Regulated by Myometrial Progesterone Receptor Isoforms. Recent genomic and epigenomic data, from human specimens and mouse models, are recruited to support the existing knowledge and offer new insights and future directions in myometrial biology.

The Estrogen Receptor α Cistrome in Human Endometrium and Epithelial Organoids

Endometrial health is affected by molecular processes that underlie estrogen responses. We assessed estrogen regulation of endometrial function by integrating the estrogen receptor α (ESR1) cistromes and transcriptomes of endometrial biopsies taken from the proliferative and mid-secretory phases of the menstrual cycle together with hormonally stimulated endometrial epithelial organoids. The cycle stage-specific ESR1 binding sites were determined by chromatin immunoprecipitation and next-generation sequencing and then integrated with changes in gene expression from RNA sequencing data to infer candidate ESR1 targets in normal endometrium. Genes with ESR1 binding in whole endometrium were enriched for chromatin modification and regulation of cell proliferation. The distribution of ESR1 binding sites in organoids was more distal from gene promoters when compared to primary endometrium and was more similar to the proliferative than the mid-secretory phase ESR1 cistrome. Inferred organoid estrogen/ESR1 candidate target genes affected formation of cellular protrusions and chromatin modification. Comparison of signaling effected by candidate ESR1 target genes in endometrium vs organoids reveals enrichment of both overlapping and distinct responses. Our analysis of the ESR1 cistromes and transcriptomes from endometrium and organoids provides important resources for understanding how estrogen affects endometrial health and function.

Myometrial progesterone receptor determines a transcription program for uterine remodeling and contractions during pregnancy

The uterine myometrium expands and maintains contractile quiescence before parturition. While the steroid hormone progesterone blocks labor, the role of progesterone signaling in myometrial expansion remains elusive. This study investigated the myometrial functions of the progesterone receptor, PGR. Pgr ablation in mouse smooth muscle leads to subfertility, oviductal embryo retention, and impaired myometrial adaptation to pregnancy. While gross morphology between mutant and control uteri are comparable, mutant uteri manifest a decrease of 76.6% oxytocin-stimulated contractility in a pseudopregnant context with a reduced expression of intracellular calcium homeostasis genes including Pde5a and Plcb4. At mid-pregnancy, the mutant myometrium exhibits discontinuous myofibers and disarrayed extracellular matrix at the conceptus site. Transcriptome of the mutant mid-pregnant uterine wall manifests altered muscle and extracellular matrix profiles and resembles that of late-pregnancy control tissues. A survey of PGR occupancy, H3K27ac histone marks, and chromatin looping annotates cis-acting elements that may direct gene expression of mid-pregnancy uteri for uterine remodeling. Further analyses suggest that major muscle and matrix regulators Myocd and Ccn2 and smooth muscle building block genes are PGR direct downstream targets. Cataloging enhancers that are topologically associated with progesterone downstream genes reveals distinctive patterns of transcription factor binding motifs in groups of enhancers and identifies potential regulatory partners of PGR outside its occupying sites. Finally, conserved correlations are found between estimated PGR activities and RNA abundance of downstream muscle and matrix genes in human myometrial tissues. In summary, PGR is pivotal to direct the molecular program for the uterus to remodel and support pregnancy.

Aberrant uterine folding in mice disrupts implantation chamber formation and alignment of embryo-uterine axes

The uterine luminal epithelium folds characteristically in mammals, including humans, horses and rodents. Improper uterine folding in horses results in pregnancy failure, but the precise function of folds remains unknown. Here, we uncover dynamic changes in the 3D uterine folding pattern during early pregnancy with the entire lumen forming pre-implantation transverse folds along the mesometrial-antimesometrial axis. Using a time course, we show that transverse folds are formed before embryo spacing, whereas implantation chambers form as the embryo begins attachment. Thus, folds and chambers are two distinct structures. Transverse folds resolve to form a flat implantation region, after which an embryo arrives at its center to attach and form the post-implantation chamber. Our data also suggest that the implantation chamber facilitates embryo rotation and its alignment along the uterine mesometrial-antimesometrial axis. Using WNT5A- and RBPJ-deficient mice that display aberrant folds, we show that embryos trapped in longitudinal folds display misalignment of the embryo-uterine axes, abnormal chamber formation and defective post-implantation morphogenesis. These mouse models with disrupted uterine folding provide an opportunity to understand uterine structure-based mechanisms that are crucial for implantation and pregnancy success.

This article has an associated ‘The people behind the papers’ interview.

Progesterone Signaling in Endometrial Epithelial Organoids

For pregnancy to be established, uterine cells respond to the ovarian hormones, estrogen, and progesterone, via their nuclear receptors, the estrogen receptor (ESR1) and progesterone receptor (PGR). ESR1 and PGR regulate genes by binding chromatin at genes and at distal enhancer regions, which interact via dynamic 3-dimensional chromatin structures. Endometrial epithelial cells are the initial site of embryo attachment and invasion, and thus understanding the processes that yield their receptive state is important. Here, we cultured and treated organoids derived from human epithelial cells, isolated from endometrial biopsies, with estrogen and progesterone and evaluated their transcriptional profiles, their PGR cistrome, and their chromatin conformation. Progesterone attenuated estrogen-dependent gene responses but otherwise minimally impacted the organoid transcriptome. PGR ChIPseq peaks were co-localized with previously described organoid ESR1 peaks, and most PGR and ESR1 peaks were in B (inactive) compartment regions of chromatin. Significantly more ESR1 peaks were assigned to estrogen-regulated genes by considering chromatin loops identified using HiC than were identified using ESR1 peak location relative to closest genes. Overall, the organoids model allowed a definition of the chromatin regulatory components governing hormone responsiveness.

Inserting Cre recombinase into the Prolactin 8a2 gene for decidua-specific recombination in mice

An estimated 75% of unsuccessful pregnancies are due to implantation failure. Investigating the causes of implantation failure is difficult as decidualization and embryo implantation is a dynamic process. Here, we describe a new decidua-specific iCre recombinase mouse strain. Utilizing CRISPR/Cas9-based genome editing, a mouse strain was developed that expresses iCre recombinase under the control of the endogenous prolactin family 8, subfamily a, member 2 (Prl8a2) promoter. iCre recombinase activity was examined by crossing with mTmG/+ or Sun1-GFP reporter alleles. iCre activity initiated reporter expression at gestational day 5.5 in the primary decidual zone and continued into mid-gestation (gestational day 9.5), with expression highly concentrated in the anti-mesometrial region. No reporter expression was observed in the ovary, oviduct, pituitary, or skeletal muscle, supporting the tissue specificity of the Prl8a2iCre in the primary decidual zone. This novel iCre line will be a valuable tool for in vivo genetic manipulation and lineage tracing to investigate functions of genetic networks and cellular dynamics associated with decidualization and infertility.

Spatial transcriptomic profiles of mouse uterine microenvironments at pregnancy day 7.5†

Uterine dysfunctions lead to fertility disorders and pregnancy complications. Normal uterine functions at pregnancy depend on crosstalk among multiple cell types in uterine microenvironments. Here, we performed the spatial transcriptomics and single-cell RNA-seq assays to determine local gene expression profiles at the embryo implantation site of the mouse uterus on pregnancy day 7.5 (D7.5). The spatial transcriptomic annotation identified 11 domains of distinct gene signatures, including a mesometrial myometrium, an anti-mesometrial myometrium, a mesometrial decidua enriched with natural killer cells, a vascular sinus zone for maternal vessel remodeling, a fetal-maternal interface, a primary decidual zone, a transition decidual zone, a secondary decidual zone, undifferentiated stroma, uterine glands, and the embryo. The scRNA-Seq identified 12 types of cells in the D7.5 uterus including three types of stromal fibroblasts with differentiated and undifferentiated markers, one cluster of epithelium including luminal and glandular epithelium, mesothelium, endothelia, pericytes, myelomonocytic cell, natural killer cells, and lymphocyte B. These single-cell RNA signatures were then utilized to deconvolute the cell-type compositions of each individual uterine microenvironment. Functional annotation assays on spatial transcriptomic data revealed uterine microenvironments with distinguished metabolic preferences, immune responses, and various cellular behaviors that are regulated by region-specific endocrine and paracrine signals. Global interactome among regions is also projected based on the spatial transcriptomic data. This study provides high-resolution transcriptome profiles with locality information at the embryo implantation site to facilitate further investigations on molecular mechanisms for normal pregnancy progression.

The role of epithelial progesterone receptor isoforms in embryo implantation

The loss of uterine epithelial progesterone receptor (PGR) is crucial for successful embryo implantation in both humans and mice. The two major isoforms PGRA and PGRB have divergent functions under both physiological and pathological conditions. The present study compares phenotypes and gene signatures of PGRA and PGRB in uterine epithelium using uterine epithelial-specific constitutively expressed PGRA or PGRB mouse models. The cistrome and transcriptome analysis reveals substantial overlap between epithelial PGRA and PGRB, and both disrupt embryo implantation through FOXO1 pathways. Constitutive epithelial PGRA and PGRB expression impairs ESR1 occupancy at the promoter of Lif leading to reduced Lif transcription and further exaggerates SGK1 expression leading to enhanced PI3K-SGK1 activities, and both contribute to the decline of nuclear FOXO1 expression. Our study demonstrates that PGRA and PGRB in the uterine epithelium act on a similar set of target genes and commonly regulate the LIF-SGK1-FOXO1 signaling pathway for embryo implantation.

Structural Equation Modeling of In silico Perturbations

Gene expression is controlled by multiple regulators and their interactions. Data from genome-wide gene expression assays can be used to estimate molecular activities of regulators within a model organism and extrapolate them to biological processes in humans. This approach is valuable in studies to better understand complex human biological systems which may be involved in diseases and hence, have potential clinical relevance. In order to achieve this, it is necessary to infer gene interactions that are not directly observed (i.e. latent or hidden) by way of structural equation modeling (SEM) on the expression levels or activities of the downstream targets of regulator genes. Here we developed an R Shiny application, termed “Structural Equation Modeling of In silico Perturbations (SEMIPs)” to compute a two-sided t-statistic (T-score) from analysis of gene expression data, as a surrogate to gene activity in a given human specimen. SEMIPs can be used in either correlational studies between outcome variables of interest or subsequent model fitting on multiple variables. This application implements a 3-node SEM model that consists of two upstream regulators as input variables and one downstream reporter as an outcome variable to examine the significance of interactions among these variables. SEMIPs enables scientists to investigate gene interactions among three variables through computational and mathematical modeling (i.e. in silico). In a case study using SEMIPs, we have shown that putative direct downstream genes of the GATA Binding Protein 2 (GATA2) transcription factor are sufficient to infer its activities in silico for the conserved progesterone receptor (PGR)-GATA2-SRY-box transcription factor 17 (SOX17) genetic network in the human uterine endometrium.

Conditional ERK3 overexpression cooperates with PTEN deletion to promote lung adenocarcinoma formation in mice

ERK3, officially known as mitogen‐activated protein kinase 6 (MAPK6), is a poorly studied mitogen‐activated protein kinase (MAPK). Recent studies have revealed the upregulation of ERK3 expression in cancer and suggest an important role for ERK3 in promoting cancer cell growth and invasion in some cancers, in particular lung cancer. However, it is unknown whether ERK3 plays a role in spontaneous tumorigenesis in vivo. To determine the role of ERK3 in lung tumorigenesis, we created a conditional ERK3 transgenic mouse line in which ERK3 transgene expression is controlled by Cre recombinase. By crossing these transgenic mice with a mouse line harboring a lung tissue–specific Cre recombinase transgene driven by a club cell secretory protein gene promoter (CCSP‐iCre), we have found that conditional ERK3 overexpression cooperates with phosphatase and tensin homolog (PTEN) deletion to induce the formation of lung adenocarcinomas (LUADs). Mechanistically, ERK3 overexpression stimulates activating phosphorylations of erb‐b2 receptor tyrosine kinases 2 and 3 (ERBB2 and ERBB3) by upregulating Sp1 transcription factor (SP1)–mediated gene transcription of neuregulin 1 (NRG1), a potent ligand for ERBB2/ERBB3. Our study has revealed a bona fide tumor‐promoting role for ERK3 using genetically engineered mouse models. Together with previous findings showing the roles of ERK3 in cultured cells and in a xenograft lung tumor model, our findings corroborate that ERK3 acts as an oncoprotein in promoting LUAD development and progression.

Poor Endometrial Proliferation After Clomiphene is Associated With Altered Estrogen Action

CONTEXT

Suboptimal endometrial thickening is associated with lower pregnancy rates and occurs in some infertile women treated with clomiphene.

OBJECTIVE

To examine cellular and molecular differences in the endometrium of women with suboptimal vs optimal endometrial thickening following clomiphene.

METHODS

Translational prospective cohort study from 2018 to 2020 at a university-affiliated clinic. Reproductive age women with unexplained infertility treated with 100 mg of clomiphene on cycle days 3 to 7 who developed optimal (≥8mm; n = 6, controls) or suboptimal (<6mm; n = 7, subjects) endometrial thickness underwent preovulatory blood and endometrial sampling. The main outcome measures were endometrial tissue architecture, abundance and location of specific proteins, RNA expression, and estrogen receptor (ER) α binding.

RESULTS

The endometrium of suboptimal subjects compared with optimal controls was characterized by a reduced volume of glandular epithelium (16% vs 24%, P = .01), decreased immunostaining of markers of proliferation (PCNA, ki67) and angiogenesis (PECAM-1), increased immunostaining of pan-leukocyte marker CD45 and ERβ, but decreased ERα immunostaining (all P < .05). RNA-seq identified 398 differentially expressed genes between groups. Pathway analysis of differentially expressed genes indicated reduced proliferation (Z-score = -2.2, P < .01), decreased angiogenesis (Z-score = -2.87, P < .001), increased inflammation (Z-score = +2.2, P < .01), and ERβ activation (Z-score = +1.6, P < .001) in suboptimal subjects. ChIP-seq identified 6 genes bound by ERα that were differentially expressed between groups (P < .01), some of which may play a role in implantation.

CONCLUSION

Women with suboptimal endometrial thickness after clomiphene exhibit aberrant ER expression patterns, architectural changes, and altered gene and protein expression suggesting reduced proliferation and angiogenesis in the setting of increased inflammation.

Dependency of human and murine LKB1-inactivated lung cancer on aberrant CRTC-CREB activation

Lung cancer with loss-of-function of the LKB1 tumor suppressor is a common aggressive subgroup with no effective therapies. LKB1-deficiency induces constitutive activation of cAMP/CREB-mediated transcription by a family of three CREB-regulated transcription coactivators (CRTC1-3). However, the significance and mechanism of CRTC activation in promoting the aggressive phenotype of LKB1-null cancer remain poorly characterized. Here, we observed overlapping CRTC expression patterns and mild growth phenotypes of individual CRTC-knockouts in lung cancer, suggesting functional redundancy of CRTC1-3. We consequently designed a dominant-negative mutant (dnCRTC) to block all three CRTCs to bind and co-activate CREB. Expression of dnCRTC efficiently inhibited the aberrantly activated cAMP/CREB-mediated oncogenic transcriptional program induced by LKB1-deficiency, and specifically blocked the growth of human and murine LKB1-inactivated lung cancer. Collectively, this study provides direct proof for an essential role of the CRTC-CREB activation in promoting the malignant phenotypes of LKB1-null lung cancer and proposes the CRTC-CREB interaction interface as a novel therapeutic target.

Cell-type specific analysis of physiological action of estrogen in mouse oviducts

One of the endogenous estrogens, 17β-estradiol (E2 ) is a female steroid hormone secreted from the ovary. It is well established that E2 causes biochemical and histological changes in the uterus. However, it is not completely understood how E2 regulates the oviductal environment in vivo. In this study, we assessed the effect of E2 on each oviductal cell type, using an ovariectomized-hormone-replacement mouse model, single-cell RNA-sequencing (scRNA-seq), in situ hybridization, and cell-type-specific deletion in mice. We found that each cell type in the oviduct responded to E2 distinctively, especially ciliated and secretory epithelial cells. The treatment of exogenous E2 did not drastically alter the transcriptomic profile from that of endogenous E2 produced during estrus. Moreover, we have identified and validated genes of interest in our datasets that may be used as cell- and region-specific markers in the oviduct. Insulin-like growth factor 1 (Igf1) was characterized as an E2 -target gene in the mouse oviduct and was also expressed in human fallopian tubes. Deletion of Igf1 in progesterone receptor (Pgr)-expressing cells resulted in female subfertility, partially due to an embryo developmental defect and embryo retention within the oviduct. In summary, we have shown that oviductal cell types, including epithelial, stromal, and muscle cells, are differentially regulated by E2 and support gene expression changes, such as growth factors that are required for normal embryo development and transport in mouse models. Furthermore, we have identified cell-specific and region-specific gene markers for targeted studies and functional analysis in vivo.

Vaginal Squamous Cell Carcinoma Develops in Mice with Conditional Arid1a Loss and Gain of Oncogenic Kras Driven by Progesterone Receptor Cre

Oncogenic KRAS mutations are a common finding in endometrial cancers. Recent sequencing studies indicate that loss-of-function mutations in the ARID1A gene are enriched in gynecologic malignant tumors. However, neither of these genetic insults alone are sufficient to develop gynecologic cancer. To determine the role of the combined effects of deletion of Arid1a and oncogenic Kras, Arid1a^flox/flox mice were crossed with Kras^{Lox-Stop-Lox-G12D/+} mice using progesterone receptor Cre (Pgr^Cre/+). Histologic analysis and immunohistochemistry of survival studies were used to characterize the mutant mouse phenotype. Hormone dependence was evaluated by ovarian hormone depletion and estradiol replacement. Arid1a^flox/flox; Kras^{Lox-Stop-Lox-G12D/+}; Pgr^Cre/+ mice were euthanized early because of invasive vaginal squamous cell carcinoma. Younger mice had precancerous intraepithelial lesions. Immunohistochemistry supported the pathological diagnosis with abnormal expression and localization of cytokeratin 5, tumor protein P63, cyclin-dependent kinase inhibitor 2A, and Ki-67, the marker of proliferation. Ovarian hormone deletion in Arid1a^flox/flox; Kras^{Lox-Stop-Lox-G12D/+}; Pgr^Cre/+ mice resulted in atrophic vaginal epithelium without evidence of vaginal tumors. Estradiol replacement in ovarian hormone-depleted Arid1a^flox/flox; Kras^{Lox-Stop-Lox-G12D/+}; Pgr^Cre/+ mice resulted in lesions that resembled the squamous cell carcinoma in intact mice. Therefore, this mouse can be used to study the transition from benign precursor lesions into invasive vaginal human papillomavirus-independent squamous cell carcinoma, offering insights into progression and pathogenesis of this rare disease.

Illuminating the "Black Box" of Progesterone-Dependent Embryo Implantation Using Engineered Mice

Synchrony between progesterone-driven endometrial receptivity and the arrival of a euploid blastocyst is essential for embryo implantation, a prerequisite event in the establishment of a successful pregnancy. Advancement of embryo implantation within the uterus also requires stromal fibroblasts of the endometrium to transform into epithelioid decidual cells, a progesterone-dependent cellular transformation process termed decidualization. Although progesterone is indispensable for these cellular processes, the molecular underpinnings are not fully understood. Because human studies are restricted, much of our fundamental understanding of progesterone signaling in endometrial periimplantation biology comes from in vitro and in vivo experimental systems. In this review, we focus on the tremendous progress attained with the use of engineered mouse models together with high throughput genome-scale analysis in disclosing key signals, pathways and networks that are required for normal endometrial responses to progesterone during the periimplantation period. Many molecular mediators and modifiers of the progesterone response are implicated in cross talk signaling between epithelial and stromal cells of the endometrium, an intercellular communication system that is critical for the ordered spatiotemporal control of embryo invasion within the maternal compartment. Accordingly, derailment of these signaling systems is causally linked with infertility, early embryo miscarriage and gestational complications that symptomatically manifest later in pregnancy. Such aberrant progesterone molecular responses also contribute to endometrial pathologies such as endometriosis, endometrial hyperplasia and cancer. Therefore, our review makes the case that further identification and functional analysis of key molecular mediators and modifiers of the endometrial response to progesterone will not only provide much-needed molecular insight into the early endometrial cellular changes that promote pregnancy establishment but lend credible hope for the development of more effective mechanism-based molecular diagnostics and precision therapies in the clinical management of female infertility, subfertility and a subset of gynecological morbidities.

Different Cre systems induce differential microRNA landscapes and abnormalities in the female reproductive tracts of Dgcr8 conditional knockout mice

OBJECTIVES

The female reproductive tract comprises several different cell types. Using three representative Cre systems, we comparatively analysed the phenotypes of Dgcr8 conditional knockout (cKO) mice to understand the function of Dgcr8, involved in canonical microRNA biogenesis, in the female reproductive tract.

MATERIALS AND METHODS

Dgcr8f/f mice were crossed with Ltficre/+ , Amhr2cre/+ or PRcre/+ mice to produce mice deficient in Dgcr8 in epithelial (Dgcr8ed/ed ), mesenchymal (Dgcr8md/md ) and all the compartments (Dgcr8td/td ) in the female reproductive tract. Reproductive phenotypes were evaluated in Dgcr8 cKO mice. Uteri and/or oviducts were used for small RNA-seq, mRNA-seq, real-time RT-PCR, and/or morphologic and histological analyses.

RESULT

Dgcr8ed/ed mice did not exhibit any distinct defects, whereas Dgcr8md/md mice showed sub-fertility and oviductal smooth muscle deformities. Dgcr8td/td mice were infertile due to anovulation and acute inflammation in the female reproductive tract and suffered from an atrophic uterus with myometrial defects. The microRNAs and mRNAs related to immune modulation and/or smooth muscle growth were systemically altered in the Dgcr8td/td uterus. Expression profiles of dysregulated microRNAs and mRNAs in the Dgcr8td/td uterus were different from those in other genotypes in a Cre-dependent manner.

CONCLUSIONS

Dgcr8 deficiency with different Cre systems induces overlapping but distinct phenotypes as well as the profiles of microRNAs and their target mRNAs in the female reproductive tract, suggesting the importance of selecting the appropriate Cre driver to investigate the genes of interest.

WNK1 regulates uterine homeostasis and its ability to support pregnancy

WNK1 (with no lysine [K] kinase 1) is an atypical kinase protein ubiquitously expressed in humans and mice. A mutation in its encoding gene causes hypertension in humans, which is associated with abnormal ion homeostasis. WNK1 is critical for in vitro decidualization in human endometrial stromal cells, thereby demonstrating its importance in female reproduction. Using a mouse model, WNK1 was ablated in the female reproductive tract to define its in vivo role in uterine biology. Loss of WNK1 altered uterine morphology, causing endometrial epithelial hyperplasia, adenomyotic features, and a delay in embryo implantation, ultimately resulting in compromised fertility. Combining transcriptomic, proteomic, and interactomic analyses revealed a potentially novel regulatory pathway whereby WNK1 represses AKT phosphorylation through protein phosphatase 2A (PP2A) in endometrial cells from both humans and mice. We show that WNK1 interacted with PPP2R1A, the alpha isoform of the PP2A scaffold subunit. This maintained the levels of PP2A subunits and stabilized its activity, which then dephosphorylated AKT. Therefore, loss of WNK1 reduced PP2A activity, causing AKT hypersignaling. Using FOXO1 as a readout of AKT activity, we demonstrate that there was escalated FOXO1 phosphorylation and nuclear exclusion, leading to a disruption in the expression of genes that are crucial for embryo implantation.

Constitutive expression of progesterone receptor isoforms promotes the development of hormone-dependent ovarian neoplasms

Differences in the relative abundances of the progesterone receptor (PGR) isoforms PGRA and PGRB are often observed in women with reproductive tract cancers. To assess the importance of the PGR isoform ratio in the maintenance of the reproductive tract, we generated mice that overexpress PGRA or PGRB in all PGR-positive tissues. Whereas few PGRA-overexpressing mice developed reproductive tract tumors, all PGRB-overexpressing mice developed ovarian neoplasms that were derived from ovarian luteal cells. Transcriptomic analyses of the ovarian tumors from PGRB-overexpressing mice revealed enhanced AKT signaling and a gene expression signature similar to those of human ovarian and endometrial cancers. Treating PGRB-overexpressing mice with the PGR antagonist RU486 stalled tumor growth and decreased the expression of cell cycle-associated genes, indicating that tumor growth and cell proliferation were hormone dependent in addition to being isoform dependent. Analysis of the PGRB cistrome identified binding events at genes encoding proteins that are critical regulators of mitotic phase entry. This work suggests a mechanism whereby an increase in the abundance of PGRB relative to that of PGRA drives neoplasia in vivo by stimulating cell cycling.

Pten and Dicer1 loss in the mouse uterus causes poorly differentiated endometrial adenocarcinoma

Endometrial cancer remains the most common gynecological malignancy in the United States. While the loss of the tumor suppressor, PTEN (phosphatase and tensin homolog), is well studied in endometrial cancer, recent studies suggest that DICER1, the endoribonuclease responsible for miRNA genesis, also plays a significant role in endometrial adenocarcinoma. Conditional uterine deletion of Dicer1 and Pten in mice resulted in poorly differentiated endometrial adenocarcinomas, which expressed Napsin A and HNF1B (hepatocyte nuclear factor 1 homeobox B), markers of clear-cell adenocarcinoma. Adenocarcinomas were hormone-independent. Treatment with progesterone did not mitigate poorly differentiated adenocarcinoma, nor did it affect adnexal metastasis. Transcriptomic analyses of DICER1 deleted uteri or Ishikawa cells revealed unique transcriptomic profiles and global miRNA downregulation. Computational integration of miRNA with mRNA targets revealed deregulated let-7 and miR-16 target genes, similar to published human DICER1-mutant endometrial cancers from TCGA (The Cancer Genome Atlas). Similar to human endometrial cancers, tumors exhibited dysregulation of ephrin-receptor signaling and transforming growth factor-beta signaling pathways. LIM kinase 2 (LIMK2), an essential molecule in p21 signal transduction, was significantly upregulated and represents a novel mechanism for hormone-independent pathogenesis of endometrial adenocarcinoma. This preclinical mouse model represents the first genetically engineered mouse model of poorly differentiated endometrial adenocarcinoma.

The histone methyltransferase EZH2 is required for normal uterine development and function in mice†

Enhancer of zeste homolog 2 (EZH2) is a rate-limiting catalytic subunit of a histone methyltransferase, polycomb repressive complex, which silences gene activity through the repressive histone mark H3K27me3. EZH2 is critical for epigenetic effects of early estrogen treatment, and may be involved in uterine development and pathologies. We investigated EZH2 expression, regulation, and its role in uterine development/function. Uterine epithelial EZH2 expression was associated with proliferation and was high neonatally then declined by weaning. Pre-weaning uterine EZH2 expression was comparable in wild-type and estrogen receptor 1 knockout mice, showing neonatal EZH2 expression is ESR1 independent. Epithelial EZH2 was upregulated by 17β-estradiol (E2) and inhibited by progesterone in adult uteri from ovariectomized mice. To investigate the uterine role of EZH2, we developed a EZH2 conditional knockout (Ezh2cKO) mouse using a cre recombinase driven by the progesterone receptor (Pgr) promoter that produced Ezh2cKO mice lacking EZH2 in Pgr-expressing tissues (e.g. uterus, mammary glands). In Ezh2cKO uteri, EZH2 was deleted neonatally. These uteri had reduced H3K27me3, were larger than WT, and showed adult cystic endometrial hyperplasia. Ovary-independent uterine epithelial proliferation and increased numbers of highly proliferative uterine glands were seen in adult Ezh2cKO mice. Female Ezh2cKO mice were initially subfertile, and then became infertile by 9 months. Mammary gland development in Ezh2cKO mice was inhibited. In summary, uterine EZH2 expression is developmentally and hormonally regulated, and its loss causes aberrant uterine epithelial proliferation, uterine hypertrophy, and cystic endometrial hyperplasia, indicating a critical role in uterine development and function.

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.

Incidence rates of and risk factors for opioid overdose in new users of prescription opioids among US Medicaid enrollees: A cohort study

PURPOSE

To measure incidence rates of and risk factors for opioid overdose among new users of prescription opioids in the Medicaid population.

METHODS

A cohort study using Medicaid claims from four states (1999-2012) among adults continuously enrolled in Medicaid for ≥3 years free of opioid prescriptions and opioid overdose before cohort entry. Exposure and outcome of interest were prescription opioid use and apparent incident opioid overdose identified in inpatient and outpatient claims (sensitivity ≈ 97%; positive predictive value ≈ 87%), respectively.

RESULTS

Among new prescription opioid users (1 336 140 persons; 246 466 person-years), the overall opioid overdose incidence rate per 100 000 person-years was 247.1 (95% confidence interval [CI], 227.5-266.7), with 251.0 (CI, 188.6-313.5) in 2002 and 225.5 (CI, 142.0-309.0) in 2012. A lower hazard for opioid overdose was seen for age 65-80 years (adjusted hazard ratio [HR], 0.50; CI, 0.37-0.66) and 80-100 years (0.35; 0.23-0.52) vs 18-35 years; females (0.79; 0.67-0.93) vs males; and other/unknown race/ethnicity (0.71; 0.54-0.93) vs whites. A higher hazard was seen for initial opioid dose in morphine milligram equivalents (MMEs), 50-100 MME/day (1.52; 1.24-1.86) and >100 MME/day (1.98; 1.55-2.53), vs <50 MME/day; prior diagnosis of substance use disorders (2.30; 1.91-2.79) or mental health conditions (1.75; 1.47-2.08); and prior prescriptions for benzodiazepines (1.43; 1.13-1.81).

CONCLUSION

In Medicaid enrollees in four study states during 2002 to 2012, opioid overdose incidence rate per 100 000 person-years among apparent new users of prescription opioids was 247.1, with 251.0 in 2002 and 225.5 in 2012. Younger ages, white race/ethnicity, higher MME opioid daily doses, prior substance use disorders, mental health conditions, and benzodiazepine prescriptions were associated with a higher risk of opioid overdose incidence.

90 YEARS OF PROGESTERONE: New insights into progesterone receptor signaling in the endometrium required for embryo implantation

Progesterone's ability to maintain pregnancy in eutherian mammals highlighted this steroid as the 'hormone of pregnancy'. It was the unique 'pro-gestational' bioactivity of progesterone that enabled eventual purification of this ovarian steroid to crystalline form by Willard Myron Allen in the early 1930s. While a functional connection between normal progesterone responses ('progestational proliferation') of the uterus with the maintenance of pregnancy was quickly appreciated, an understanding of progesterone's involvement in the early stages of pregnancy establishment was comparatively less well understood. With the aforementioned as historical backdrop, this review focuses on a selection of key advances in our understanding of the molecular mechanisms by which progesterone, through its nuclear receptor (the progesterone receptor), drives the development of endometrial receptivity, a transient uterine state that allows for embryo implantation and the establishment of pregnancy. Highlighted in this review are the significant contributions of advanced mouse engineering and genome-wide transcriptomic and cistromic analytics which reveal the pivotal molecular mediators and modifiers that are essential to progesterone-dependent endometrial receptivity and decidualization. With a clearer understanding of the molecular landscape that underpins uterine responsiveness to progesterone during the periimplantation period, we predict that common gynecologic morbidities due to abnormal progesterone responsiveness will be more effectively diagnosed and/or treated in the future.

Interleukin-13 receptor subunit alpha-2 is a target of progesterone receptor and steroid receptor coactivator-1 in the mouse uterus†

The endometrium, composed of epithelial and stromal cell compartments, is tightly regulated by the ovarian steroid hormones estrogen (E2) and progesterone (P4) during early pregnancy. Through the progesterone receptor (PGR), steroid receptor coactivators, and other transcriptional coregulators, progesterone inhibits E2-induced cell proliferation and induces the differentiation of stromal cells in a process called decidualization to promote endometrial receptivity. Although interleukin-13 receptor subunit alpha-2 (Il13ra2) is expressed in the human and mouse endometrium, its potential role in the steroid hormone regulation of the endometrium has not been thoroughly examined. In this study, we employed PGR knockout mice and steroid receptor coactivator-1 knockout mice (SRC-1-/-) to profile the expression of Il13ra2 in the murine endometrium and determine the role of these transcriptional regulators in the hormone-responsiveness of Il13ra2 expression. Furthermore, we utilized a well-established decidualization-inducing steroidogenic cocktail and a siRNA-based knockdown of IL13RA2 to determine the importance of IL13RA2 in the decidualization of primary human endometrial stromal cells. Our findings demonstrate that Il13ra2 is expressed in the subepithelial stroma of the murine endometrium in response to ovarian steroid hormones and during early pregnancy in a PGR- and SRC-1-dependent manner. Furthermore, we show that knockdown of IL13RA2 before in vitro decidualization of primary human endometrial stromal cells partially compromises the full decidualization response. We conclude that Il13ra2 is a downstream target of progesterone through PGR and SRC-1 and plays a role in mediating the stromal action of ovarian steroid hormones.

Estrogen receptor α (ERα)-binding super-enhancers drive key mediators that control uterine estrogen responses in mice

Estrogen receptor α (ERα) modulates gene expression by interacting with chromatin regions that are frequently distal from the promoters of estrogen-regulated genes. Active chromatin-enriched "super-enhancer" (SE) regions, mainly observed in in vitro culture systems, often control production of key cell type-determining transcription factors. Here, we defined super-enhancers that bind to ERα in vivo within hormone-responsive uterine tissue in mice. We found that SEs are already formed prior to estrogen exposure at the onset of puberty. The genes at SEs encoded critical developmental factors, including retinoic acid receptor α (RARA) and homeobox D (HOXD). Using high-throughput chromosome conformation capture (Hi-C) along with DNA sequence analysis, we demonstrate that most SEs are located at a chromatin loop end and that most uterine genes in loop ends associated with these SEs are regulated by estrogen. Although the SEs were formed before puberty, SE-associated genes acquired optimal ERα-dependent expression after reproductive maturity, indicating that pubertal processes that occur after SE assembly and ERα binding are needed for gene responses. Genes associated with these SEs affected key estrogen-mediated uterine functions, including transforming growth factor β (TGFβ) and LIF interleukin-6 family cytokine (LIF) signaling pathways. To the best of our knowledge, this is the first identification of SE interactions that underlie hormonal regulation of genes in uterine tissue and optimal development of estrogen responses in this tissue.

KMT2D Deficiency Impairs Super-Enhancers to Confer a Glycolytic Vulnerability in Lung Cancer

Epigenetic modifiers frequently harbor loss-of-function mutations in lung cancer, but their tumor-suppressive roles are poorly characterized. Histone methyltransferase KMT2D (a COMPASS-like enzyme, also called MLL4) is among the most highly inactivated epigenetic modifiers in lung cancer. Here, we show that lung-specific loss of Kmt2d promotes lung tumorigenesis in mice and upregulates pro-tumorigenic programs, including glycolysis. Pharmacological inhibition of glycolysis preferentially impedes tumorigenicity of human lung cancer cells bearing KMT2D-inactivating mutations. Mechanistically, Kmt2d loss widely impairs epigenomic signals for super-enhancers/enhancers, including the super-enhancer for the circadian rhythm repressor Per2. Loss of Kmt2d decreases expression of PER2, which regulates multiple glycolytic genes. These findings indicate that KMT2D is a lung tumor suppressor and that KMT2D deficiency confers a therapeutic vulnerability to glycolytic inhibitors.

Oviductal Retention of Embryos in Female Mice Lacking Estrogen Receptor α in the Isthmus and the Uterus

Estrogen receptor α (ESR1; encoded by Esr1) is a crucial nuclear transcription factor for female reproduction and is expressed throughout the female reproductive tract. To assess the function of ESR1 in reproductive tissues without confounding effects from a potential developmental defect arising from global deletion of ESR1, we generated a mouse model in which Esr1 was specifically ablated during postnatal development. To accomplish this, a progesterone receptor Cre line (PgrCre) was bred with Esr1f/f mice to create conditional knockout of Esr1 in reproductive tissues (called PgrCreEsr1KO mice) beginning around 6 days after birth. In the PgrCreEsr1KO oviduct, ESR1 was most efficiently ablated in the isthmic region. We found that at 3.5 days post coitus (dpc), embryos were retrieved from the uterus in control littermates while all embryos were retained in the PgrCreEsr1KO oviduct. Additionally, serum progesterone (P4) levels were significantly lower in PgrCreEsr1KO compared to controls at 3.5 dpc. This finding suggests that expression of ESR1 in the isthmus and normal P4 levels allow for successful embryo transport from the oviduct to the uterus. Therefore, alterations in oviductal isthmus ESR1 signaling and circulating P4 levels could be related to female infertility conditions such as tubal pregnancy.

Molecular Studies on Pregnancy with Mouse Models

Pregnancy is a complex process that involves crosstalk among multiple cell types in both the endometrial and myometrial compartments at the maternal side to support the fetus. Genetic engineered mouse models have served as a major platform to dissect the convolute genetic interactions in a physiological context. Combining with various applications of next generation sequencing and genome editing, functional assays by mouse models have expanded the spectrum to include both coding and noncoding genome. The present review will highlight recent findings that are primarily based on studies of mouse models with emphasis on pathways for endometrial receptivity and myometrial contraction. Emerging novel technologies that may advance the research in these two aspects will also be discussed.

Dynamic transcriptome, accessible genome, and PGR cistrome profiles in the human myometrium

The myometrium undergoes structural and functional remodeling during pregnancy. We hypothesize that myometrial genomic elements alter correspondingly in preparation for parturition. Human myometrial tissues from nonpregnant (NP) and term pregnant (TP) human subjects were examined by RNAseq, ATACseq, and PGR ChIPseq assays to profile transcriptome, assessible genome, and PGR occupancy. NP and TP specimens exhibit 2890 differentially expressed genes, reflecting an increase of metabolic, inflammatory, and PDGF signaling, among others, in adaptation to pregnancy. At the epigenome level, patterns of accessible genome change between NP and TP myometrium, leading to the altered enrichment of binding motifs for hormone and muscle regulators such as the progesterone receptor (PGR), Krüppel-like factors, and MEF2A transcription factors. PGR genome occupancy exhibits a significant difference between the two stages of the myometrium, concomitant with distinct transcriptomic profiles including genes such as ENO1, LHDA, and PLCL1 in the glycolytic and calcium signaling pathways. Over-representation of SRF, MYOD, and STAT binding motifs in PGR occupying sites further suggests interactions between PGR and major muscle regulators for myometrial gene expression. In conclusion, changes in accessible genome and PGR occupancy are part of the myometrial remodeling process and may serve as mechanisms to formulate the state-specific transcriptome profiles.

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.

Tissue-specific progesterone receptor-chromatin binding and the regulation of progesterone-dependent gene expression

Progesterone receptor (PGR) co-ordinately regulates ovulation, fertilisation and embryo implantation through tissue-specific actions, but the mechanisms for divergent PGR action are poorly understood. Here we characterised PGR activity in mouse granulosa cells using combined ChIP-seq for PGR and H3K27ac and gene expression microarray. Comparison of granulosa, uterus and oviduct PGR-dependent genes showed almost complete tissue specificity in PGR target gene profiles. In granulosa cells 82% of identified PGR-regulated genes bound PGR within 3 kb of the gene and PGR binding sites were highly enriched in proximal promoter regions in close proximity to H3K27ac-modified active chromatin. Motif analysis showed highly enriched PGR binding to the PGR response element (GnACAnnnTGTnC), but PGR also interacted significantly with other transcription factor binding motifs. In uterus PGR showed far more tendency to bind intergenic chromatin regions and low evidence of interaction with other transcription factors. This is the first genome-wide description of PGR action in granulosa cells and systematic comparison of diverse PGR action in different reproductive tissues. It clarifies finely-tuned contextual PGR-chromatin interactions with implications for more targeted reproductive medicine.

Uterine Gαq/11 signaling, in a progesterone-dependent manner, critically regulates the acquisition of uterine receptivity in the female mouse

A nonreceptive uterus is a major cause of embryo implantation failure. This study examined the importance of the Gαq/11-coupled class of GPCRs as regulators of uterine receptivity. Mice were created lacking uterine Gαq and Gα11; as a result, signaling by all uterine Gαq/11-coupled receptors was disrupted. Reproductive profiling of the knockout females revealed that on d 4 of pregnancy, despite adequate serum progesterone (P4) levels and normal P4 receptor (PR) expression, there was no evidence of PR signaling. This resulted in the down-regulation of heart and neural crest derivatives expressed 2, Kruppel-like factor 15, and cyclin G1 and the subsequent persistent proliferation of the luminal epithelium. Aquaporin (Aqp) 11 was also potently down-regulated, whereas Aqp5/AQP5 expression persisted, resulting in the inhibition of luminal closure. Hypertrophy of the myometrial longitudinal muscle was also dramatically diminished, likely contributing to the observed implantation failure. Further analyses revealed that a major mechanism via which uterine Gαq/11 signaling induces PR signaling is through the transcriptional up-regulation of leucine-rich repeat-containing GPCR 4 (Lgr4). LGR4 was previously identified as a trigger of PR activation and signaling. Overall, this study establishes that Gαq/11 signaling, in a P4-dependent manner, critically regulates the acquisition of uterine receptivity in the female mouse, and disruption of such signaling results in P4 resistance.-de Oliveira, V., Schaefer, J., Calder, M., Lydon, J. P., DeMayo, F. J., Bhattacharya, M., Radovick, S., Babwah, A. V. Uterine Gαq/11 signaling, in a progesterone-dependent manner, critically regulates the acquisition of uterine receptivity in the female mouse.

Uterine function in the mouse requires speckle-type poz protein

Speckle-type poz protein (SPOP) is an E3-ubiquitin ligase adaptor for turnover of a diverse number of proteins involved in key cellular processes such as chromatin remodeling, transcriptional regulation, and cell signaling. Genomic analysis revealed that SPOP somatic mutations are found in a subset of endometrial cancers, suggesting that these mutations act as oncogenic drivers of this gynecologic malignancy. These studies also raise the question as to the role of wild-type SPOP in normal uterine function. To address this question, we generated a mouse model (Spopd/d) in which SPOP is ablated in uterine cells that express the PGR. Fertility studies demonstrated that SPOP is required for embryo implantation and for endometrial decidualization. Molecular analysis revealed that expression levels of the PGR at the protein and transcript level are significantly reduced in the Spopd/d uterus. While this result was unexpected, this finding explains in part the dysfunctional phenotype of the Spopd/d uterus. Moderate increased levels of the ESR1, GATA2, and SRC2 were detected in the Spopd/d uterus, suggesting that SPOP is required to maintain the proteome for normal uterine function. With age, the Spopd/d endometrium exhibits large glandular cysts with foci of epithelial proliferation, further supporting a role for SPOP in maintaining a healthy uterus. Collectively, studies on the Spopd/d mouse support an important role for SPOP in normal uterine function and suggest that this mouse model may prove useful to study the role of SPOP-loss-of-function mutations in the etiopathogenesis of endometrial cancer.

SFRP4 Is a Negative Regulator of Ovarian Follicle Development and Female Fertility

WNT signaling regulates a variety of ovarian processes, including follicle development, granulosa cell (GC) proliferation and differentiation, steroidogenesis, and ovulation. The secreted frizzled-related proteins (SFRPs) comprise a family of WNT signaling antagonists. Sfrp4 expression was previously reported to be induced in ovarian GCs and cumulus cells in vivo following human chorionic gonadotropin treatment, suggesting that it may play key roles in cumulus expansion, ovulation/luteinization, and corpus luteum (CL) function. In this study, we aimed to define the physiological roles of Sfrp4 in the ovary by gene targeting. Sfrp4-null female mice were found to produce larger litters than did their wild-type littermates. Although previous studies had suggested roles of Sfrp4 in luteal cell survival, no differences in CL formation, morphology, steroidogenesis, involution, or luteal cell apoptosis were found in Sfrp4-null mice. Likewise, cumulus expansion occurred normally in Sfrp4-null mice, with minimal changes in cumulus cell gene expression. Hyperfertility in the Sfrp4-null model was ultimately attributed to decreased antral follicle atresia, leading to an enhanced ovulatory rate. Increased expression of FSH- and LH-responsive genes was found in GCs from Sfrp4-null mice, and GCs isolated from Sfrp4-null mice were found to be hyperresponsive to FSH and LH in vitro. Although Sfrp2 was found to be overexpressed in the GCs of Sfrp4-null mice (suggesting a compensatory mechanism), Sfrp2-null mice had normal fertility and ovulatory rates, and Sfrp2/4 double knockout mice did not differ from Sfrp4-null mice. Taken together, our results suggest that SFRP4 acts to attenuate GC responsiveness to gonadotropins, thereby decreasing follicle survival, ovulatory rate, and fertility.

ERBB2 Regulates MED24 during Cancer Progression in Mice with Pten and Smad4 Deletion in the Pulmonary Epithelium

ERBB2 is an oncogenic driver with frequent gene mutations and amplification in human lung tumors and is an attractive target for lung cancer therapy. However, target therapies can be improved by understanding the in vivo mechanisms regulated by ERBB2 during lung tumor development. Here, we generated genetic mouse models to show that Erbb2 loss inhibited lung tumor development induced by deletion of Pten and Smad4. Transcriptome analysis showed that Erbb2 loss suppressed the significant changes of most of the induced genes by ablation of Pten and Smad4. Overlapping with ERBB2-associated human lung cancer genes further identified those ERBB2 downstream players potentially conserved in human and mouse lung tumors. Furthermore, MED24 was identified as a crucial oncogenic target of ERBB2 in lung tumor development. Taken together, ERBB2 is required for the dysregulation of cancer-related genes, such as MED24, during lung tumor development.

Human endometrial stromal cell decidualization requires transcriptional reprogramming by PLZF

Infertility and early embryo miscarriage is linked to inadequate endometrial decidualization. Although transcriptional reprogramming is known to drive decidualization in response to progesterone, the key signaling effectors that directly mediate this hormone response are not fully known. This knowledge gap is clinically significant because identifying the early signals that directly mediate progesterone-driven decidualization will address some of the current limitations in diagnosing and therapeutically treating patients at most risk for early pregnancy loss. We recently revealed that the promyelocytic leukemia zinc finger (PLZF) is a direct target of the progesterone receptor and is essential for decidualization of human endometrial stromal cells (hESCs). The purpose of this current work was to identify the genome-wide transcriptional program that is controlled by PLZF during hESC decidualization using an established in vitro hESC culture model, siRNA-mediated knockdown methods, and RNA-sequencing technology followed by bioinformatic analysis and validation. We discovered that PLZF is critical in the regulation of genes that are involved in cellular processes that are essential for the archetypal morphological and functional changes that occur when hESCs transform into epithelioid decidual cells such as proliferation and cell motility. We predict that the transcriptome datasets identified in this study will not only contribute to a broader understanding of PLZF-dependent endometrial decidualization at the molecular level but may advance the development of more effective molecular diagnostics and therapeutics for the clinical management of female infertility and subfertility that is based on a dysfunctional endometrium.