Granulosa cell-expressed BMPR1A and BMPR1B have unique functions in regulating fertility but act redundantly to suppress ovarian tumor development

Hypobaric hypoxia causes low fecundity in zebrafish parents and impairment of skeletal development in zebrafish embryos and rat offspring

Hypobaric Hypoxia (HH) negatively affects the cardiovascular and respiratory systems as well as gonadal development and the therefore next generation. This study investigated the effects of HH on zebrafish and SD rats, by exposing them to a low-pressure environment at 6000 m elevation for 30 days to simulate high-altitude conditions. It was indicated that parental zebrafish reared amh under HH had increased embryo mortality, reduced hatchability, and abnormal cartilage development in the offspring. Furthermore, the HH-exposed SD rats had fewer reproductive cells and smaller litters. Moreover, the transcriptome analysis revealed the down-regulation of steroid hormone biosynthesis pathways. The expression of the gonad-associated genes (amh, pde8a, man2a2 and lhcgr), as well as the gonad and cartilage-related gene bmpr1a, were also down-regulated. In addition, Western blot analysis validated reduced bmpr1a protein expression in the ovaries of HH-treated rats. In summary, these data indicate the negative impact of HH on reproductive organs and offspring development, emphasizing the need for further research and precautions to protect future generations' health.

Transcriptomic signature of luteinized cumulus cells of oocytes developing to live birth after women received intracytoplasmic sperm injection

OBJECTIVE

To compare the transcriptome of human cumulus cells (CCs) from oocytes with different outcomes (pregnancy yes/no, live birth [LB] yes/no), to identify noninvasive biomarkers for oocyte selection as well as new therapeutic targets to increase LB rates from assisted reproductive technologies (ART).

DESIGN

Retrospective observational study.

SETTINGS

This study was conducted at a University Hospital in Switzerland.

PATIENTS

Subfertile couples undergoing controlled ovarian superstimulation and intracytoplasmic sperm injection with subsequent unbiopsied embryo transfer below the female age of 43 years.

INTERVENTION(S)

RNA sequencing of CCs from oocytes results in a pregnancy, no pregnancy, LB, or no LB.

MAIN OUTCOME MEASURES

Differential gene expression (DEG) between CCs of oocytes results in "no pregnancy" vs. "pregnancy" and "pregnancy only" vs. "live birth."

RESULTS

Although RNA sequencing did not reveal DEGs when comparing the transcriptomic profiles of the groups "no pregnancy" with "pregnancy," we identified 139 DEGs by comparing "pregnancy only" with "live birth," of which 28 belonged to clusters relevant to successful ART outcomes (i.e., CTGF, SERPINE2, PCK1, HHIP, HS3ST, and BIRC5). A functional enrichment analysis revealed that the transcriptome of CCs associated with LB depicts pathways of extracellular matrix, inflammatory cascades leading to ovulation, cell patterning, proliferation, and differentiation, and silencing pathways leading to apoptosis.

CONCLUSION

We identified a CCs transcriptomic profile associated with LB after embryo transfer that, after further validation, could serve to predict successful ART outcomes. The definition of relevant pathways of CCs related to oocyte competency contributes to a broader understanding of the cumulus oocyte complex and helps identify further therapeutic targets for improving ART success.

Endometrial TGFβ signaling fosters early pregnancy development by remodeling the fetomaternal interface

The endometrium is a unique and highly regenerative tissue with crucial roles during the reproductive lifespan of a woman. As the first site of contact between mother and embryo, the endometrium, and its critical processes of decidualization and immune cell recruitment, play a leading role in the establishment of pregnancy, embryonic development, and reproductive capacity. These integral processes are achieved by the concerted actions of steroid hormones and a myriad of growth factor signaling pathways. This review focuses on the roles of the transforming growth factor β (TGFβ) pathway in the endometrium during the earliest stages of pregnancy through the lens of immune cell regulation and function. We discuss how key ligands in the TGFβ family signal through downstream SMAD transcription factors and ultimately remodel the endometrium into a state suitable for embryo implantation and development. We also focus on the key roles of the TGFβ signaling pathway in recruiting uterine natural killer cells and their collective remodeling of the decidua and spiral arteries. By providing key details about immune cell populations and TGFβ signaling within the endometrium, it is our goal to shed light on the intricate remodeling that is required to achieve a successful pregnancy.

Behavioral and Physiological Differences in Female Rabbits at Different Stages of the Estrous Cycle

Estrus involves a series of complex physiological signs and changes in behavior before ovulation, which play a crucial role in animal reproduction. However, there have been few studies that evaluate behaviors during the different stages of estrus cycle in female rabbits. Therefore, more detailed information is needed on distinguishing the various stages of the estrous cycle. This study explored the behavioral and physiological differences at various estrous cycle stages in female New Zealand White rabbits. The continuous recording method was employed to record the daily behaviors of twenty postpartum female rabbits during the estrous cycle. Compared with the diestrus stage, the duration of foraging and drinking behavior in estrus decreased significantly, and the frequency of grooming and biting behaviors increased (p < 0.05). Differences in reproductive hormone levels (FSH, LH, P4, and E2) and follicle development were measured at each stage via ELISA and HE staining. The FSH and LH levels showed an increasing trend and then decreased, with the lowest being in late estrus (p < 0.05). The P4 level was the lowest in estrus (p < 0.05), and E2 showed a gradually increasing trend. There was no significant difference in the number of primordial follicles at each stage, but the number of primary follicles in estrus was significantly higher than at the other stages (p < 0.05). To further understand the molecular regulation mechanism of the estrous cycle in female rabbits, we analyzed the ovarian transcription patterns of female rabbits in diestrus (D group) and estrus (E group) employing RNA-seq. A total of 967 differentially expressed genes (DEGs) were screened from the ovaries of female rabbits between the diestrus and estrus groups. A KEGG analysis of DEGs enriched in the estrogen signaling pathway, aldosterone synthesis, and secretion pathway, such as CYP19A1 and IGF1R, was performed. The rabbits' behavior, related physiological hormones, and molecular regulation also differed at different estrous cycle stages. The results provide recommendations for the adequate management practices of postpartum re-estrus and breeding female rabbits.

Bone morphogenetic protein signaling is a possible therapeutic target in gynecologic cancer

Bone morphogenetic proteins (BMPs) belong to the transforming growth factor β (TGFβ) superfamily. BMPs play crucial roles in embryogenesis and bone remodeling. Recently, BMP signaling has been found to have diverse effects on different types of tumors. In this review, we summarized the effects of BMP signaling on gynecologic cancer. BMP signaling has tumor-promoting effects on ovarian cancer (OC) and endometrial cancer (EC), whereas it has tumor-suppressing effects on uterine cervical cancer (UCC). Interestingly, EC has frequent gain-of-function mutations in ACVR1, encoding one of the type I BMP receptors, which are also observed in fibrodysplasia ossificans progressiva and diffuse intrinsic pontine glioma. Little is known about the relationship between BMP signaling and other gynecologic cancers. Tumor-promoting effects of BMP signaling in OC and EC are dependent on the promotion of cancer stemness and epithelial-mesenchymal transition (EMT). In accordance, BMP receptor kinase inhibitors suppress the cell growth and migration of OC and EC. Since both cancer stemness and EMT are associated with chemoresistance, BMP signaling activation might also be an important mechanism by which OC and EC patients acquire chemoresistance. Therefore, BMP inhibitors are promising for OC and EC patients even if they become resistant to standard chemotherapy. In contrast, BMP signaling inhibits UCC growth in vitro. However, the in vivo effects of BMP signaling have not been elucidated in UCC. In conclusion, BMP signaling has a variety of functions, depending on the types of gynecologic cancer. Therefore, targeting BMP signaling should improve the treatment of patients with gynecologic cancer.

Local regulation of antral follicle development and ovulation in monovulatory species

The identification of mutations in the genes encoding bone morphogenetic protein 15 (BMP15) and growth and differentiation factor 9 (GDF9) associated with phenotypes of sterility or increased ovulation rate in sheep aroused interest in the study of the role of local factors in preantral and antral folliculogenesis in different species. An additive mutation in the BMP15 receptor, BMPR1b, which determines an increase in the ovulatory rate, has been introduced in several sheep breeds to increase the number of lambs born. Although these mutations indicate extremely relevant functions of these factors, the literature data on the regulation of the expression and function of these proteins and their receptors are very controversial, possibly due to differences in experimental models. The present review discusses the published data and preliminary results obtained by our group on the participation of local factors in the selection of the dominant follicle, ovulation, and follicular atresia in cattle, focusing on transforming growth factors beta and their receptors. The study of the expression pattern and the functionality of proteins produced by follicular cells and their receptors will allow increasing the knowledge about this local system, known to be involved in ovarian physiopathology and with the potential to promote contraception or increase the ovulation rate in mammals.

Molecular versatility during pluripotency progression

A challenge during development is to ensure lineage segregation while preserving plasticity. Using pluripotency progression as a paradigm, we review how developmental transitions are coordinated by redeployments, rather than global resettings, of cellular components. We highlight how changes in response to extrinsic cues (FGF, WNT, Activin/Nodal, Netrin-1), context- and stoichiometry-dependent action of transcription factors (Oct4, Nanog) and reconfigurations of epigenetic regulators (enhancers, promoters, TrxG, PRC) may confer robustness to naïve to primed pluripotency transition. We propose the notion of Molecular Versatility to regroup mechanisms by which molecules are repurposed to exert different, sometimes opposite, functions in close stem cell configurations.

Identification and characterization of unique and common lncRNAs and mRNAs in the pituitary, ovary, and uterus of Hu sheep with different prolificacy

LncRNAs are regarded as regulators in various animal reproductive physiological processes. However, the regulation of lncRNAs in the reproductive organ development of Hu sheep with different prolificacy remains unknown. Herein, numerous tissue-unique and -common differentially expressed lncRNAs (DELs) and differentially expressed genes (DEGs), and fecundity-unique DELs and DEGs were identified among different comparison groups at horizontal and vertical levels. Moreover, the tissue-unique and -common, and fecundity-unique female reproduction-associated DEGs and DELs were screened, and the interaction networks were constructed. Furthermore, MSTRG.43442.1 was mainly present in the cytoplasm of tested cells. The key genes ADAMTS1 and DCN were mainly localized in the granulosa cells, pituitary cells and/or endometrial epithelial cells of ovary, pituitary and/or uterus. Overall, this study identified large numbers of unique and common DELs and DEGs in the female reproductive organs of Hu sheep with different prolificacy and provided new insights into understanding the regulation of Hu sheep fecundity.

Aberrant activation of KRAS in mouse theca-interstitial cells results in female infertility

KRAS plays critical roles in regulating a range of normal cellular events as well as pathological processes in many tissues mediated through a variety of signaling pathways, including ERK1/2 and AKT signaling, in a cell-, context- and development-dependent manner. The in vivo function of KRAS and its downstream targets in gonadal steroidogenic cells for the development and homeostasis of reproductive functions remain to be determined. To understand the functions of KRAS signaling in gonadal theca and interstitial cells, we generated a Kras mutant (tKrasMT) mouse line that selectively expressed a constitutively active KrasG12D in these cells. KrasG12D expression in ovarian theca cells did not block follicle development to the preovulatory stage. However, tKrasMT females failed to ovulate and thus were infertile. The phosphorylated ERK1/2 and forkhead box O1 (FOXO1) and total FOXO1 protein levels were markedly reduced in tKrasMT theca cells. KrasG12D expression in theca cells also curtailed the phosphorylation of ERK1/2 and altered the expression of several ovulation-related genes in gonadotropin-primed granulosa cells. To uncover downstream targets of KRAS/FOXO1 signaling in theca cells, we found that the expression of bone morphogenic protein 7 (Bmp7), a theca-specific factor involved in ovulation, was significantly elevated in tKrasMT theca cells. Chromosome immunoprecipitation assays demonstrated that FOXO1 interacted with the Bmp7 promoter containing forkhead response elements and that the binding activity was attenuated in tKrasMT theca cells. Moreover, Foxo1 knockdown caused an elevation, whereas Foxo1 overexpression resulted in an inhibition of Bmp7 expression, suggesting that KRAS signaling regulates FOXO1 protein levels to control Bmp7 expression in theca cells. Thus, the anovulation phenotype observed in tKrasMT mice may be attributed to aberrant KRAS/FOXO1/BMP7 signaling in theca cells. Our work provides the first in vivo evidence that maintaining normal KRAS activity in ovarian theca cells is crucial for ovulation and female fertility.

XGBG: A Novel Method for Identifying Ovarian Carcinoma Susceptible Genes Based on Deep Learning

Ovarian carcinomas (OCs) represent a heterogeneous group of neoplasms consisting of several entities with pathogenesis, molecular profiles, multiple risk factors, and outcomes. OC has been regarded as the most lethal cancer among women all around the world. There are at least five main types of OCs classified by the fifth edition of the World Health Organization of tumors: high-/low-grade serous carcinoma, mucinous carcinoma, clear cell carcinoma, and endometrioid carcinoma. With the improved knowledge of genome-wide association study (GWAS) and expression quantitative trait locus (eQTL) analyses, the knowledge of genomic landscape of complex diseases has been uncovered in large measure. Moreover, pathway analyses also play an important role in exploring the underlying mechanism of complex diseases by providing curated pathway models and information about molecular dynamics and cellular processes. To investigate OCs deeper, we introduced a novel disease susceptible gene prediction method, XGBG, which could be used in identifying OC-related genes based on different omics data and deep learning methods. We first employed the graph convolutional network (GCN) to reconstruct the gene features based on both gene feature and network topological structure. Then, a boosting method is utilized to predict OC susceptible genes. As a result, our model achieved a high AUC of 0.7541 and an AUPR of 0.8051, which indicates the effectiveness of the XGPG. Based on the newly predicted OC susceptible genes, we gathered and researched related literatures to provide strong support to the results, which may help in understanding the pathogenesis and mechanisms of the disease.

Transcriptomic Profiling of Gene Expression Associated with Granulosa Cell Tumor Development in a Mouse Model

Ovarian granulosa cell tumors (GCTs) are rare sex cord-stromal tumors, accounting for ~5% ovarian tumors. The etiology of GCTs remains poorly defined. Genetically engineered mouse models are potentially valuable for understanding the pathogenesis of GCTs. Mice harboring constitutively active TGFβ signaling (TGFBR1-CA) develop ovarian GCTs that phenocopy several hormonal and molecular characteristics of human GCTs. To determine molecular alterations in the ovary upon TGFβ signaling activation, we performed transcriptomic profiling of gene expression associated with GCT development using ovaries from 1-month-old TGFBR1-CA mice and age-matched controls. RNA-sequencing and bioinformatics analysis coupled with the validation of select target genes revealed dysregulations of multiple cellular events and signaling molecules/pathways. The differentially expressed genes are enriched not only for known GCT-related pathways and tumorigenic events but also for signaling events potentially mediated by neuroactive ligand-receptor interaction, relaxin signaling, insulin signaling, and complements in TGFBR1-CA ovaries. Additionally, a comparative analysis of our data in mice with genes dysregulated in human GCTs or granulosa cells overexpressing a mutant FOXL2, the genetic hallmark of adult GCTs, identified some common genes altered in both conditions. In summary, this study has revealed the molecular signature of ovarian GCTs in a mouse model that harbors the constitutive activation of TGFBR1. The findings may be further exploited to understand the pathogenesis of a class of poorly defined ovarian tumors.

Control of ovarian follicle development by TGFβ family signaling

The reproductive lifespan of female mammals is limited and ultimately depends on the production of a sufficient number of high quality oocytes from a pool of non-growing primordial follicles that are set aside during embryonic and perinatal development. Recent studies show multiple signaling pathways are responsible for maintaining primordial follicle arrest and regulation of activation. Identification of these pathways and their regulatory mechanisms is essential for developing novel treatments for female infertility, improving existing in vitro fertilization techniques, and more recently, restoring the function of cryopreserved ovarian tissue. This review focuses on recent developments in transforming growth factor beta (TGFβ) family signaling in ovarian follicle development and its potential application to therapeutic design. Mouse models have been an essential tool for discovering genes critical for fertility, and recent advancements in human organ culture have additionally allowed for the translation of murine discoveries into human research and clinical settings.

Expression of steroidogenic enzymes and TGFβ superfamily members in follicular cells of prepubertal gilts with distinct endocrine profiles

Regulation of the transforming growth factor beta (TGFβ) superfamily by gonadotrophins in swine follicular cells is not fully understood. This study evaluated the expression of steroidogenic enzymes and members of the TGFβ superfamily in prepubertal gilts allocated to three treatments: 1200 IU eCG at D -3 (eCG); 1200 IU eCG at D -6 plus 500 IU hCG at D -3 (eCG + hCG); and the control, composed of untreated gilts. Blood samples and ovaries were collected at slaughter (D0) and follicular cells were recovered thereafter. Relative gene expression was determined by real-time PCR. Serum progesterone levels were greater in the eCG + hCG group compared with the other groups (P < 0.01). No differences were observed in the expression of BMP15, BMPR1A, BMPR2, FSHR, GDF9, LHCGR and TGFBR1 (P > 0.05). Gilts from the eCG group presented numerically greater mean expression of CYP11A1 mRNA than in the control group that approached statistical significance (P = 0.08) and greater expression of CYP19A1 than in both the eCG and the control groups (P < 0.05). Expression of BMPR1B was lower in the eCG + hCG treatment group compared with the control (P < 0.05). In conclusion, eCG treatment increased the relative expression of steroidogenic enzymes, whereas treatment with eCG + hCG increased serum progesterone levels. Although most of the evaluated TGFβ members were not regulated after gonadotrophin treatment, the downregulation of BMPR1B observed after treatment with eCG + hCG and suggests a role in luteinization regulation.

GTF2IRD1 overexpression promotes tumor progression and correlates with less CD8+ T cells infiltration in pancreatic cancer

Background: General Transcription Factor II-I Repeat Domain-Containing Protein 1 (GTF2IRD1) is a member of the GTF21 gene family, which encodes a set of multifunctional transcription factors. However, the potential function of GTF2IRD1 in pancreatic cancer (PC) still remains unknown. Study on GTF2IRD1 might provide a new insight into the carcinogenesis and therapeutics of PC.

Methods: In the current study, the clinical significance and potential biological of GTF2IRD1 were evaluated by bioinformatics analysis. The oncogenic role of GTF2IRD1 in PC was also determined using in vitro studies. Possible associations between GTF2IRD1 expression and tumor immunity were analyzed using ESTIMATE algorithm and single-sample Gene Set Enrichment Analysis (ssGSEA).

Results: GTF2IRD1 expression was significantly up-regulated in tumor tissues, and positively associated with higher histologic grade, higher American Joint Committee on Cancer (AJCC) stage, and worse prognosis. Function enrichment analysis demonstrated that GTF2IRD1 may be involved in pancreatic adenocarcinoma pathway, TGF-β signaling pathway, and tumor-infiltrating lymphocyte (TIL) related biological functions, such as T-cell receptor signaling pathway, leukocyte transendothelial migration, resistin as a regulator of inflammation, and regulation of leukocyte-mediated cytotoxicity. Knockdown of GTF2IRD1 expression inhibited cancer cell proliferation, colony formation, and invasion in vitro. ESTIMATE algorithm and ssGSEA demonstrated that GTF2IRD1 expression negatively correlated with the infiltration and anti-tumor activity of TILs, especially for CD8⁺ T cells.

Conclusion: The study demonstrates that GTF2IRD1 overexpression promotes tumor progression and correlates with less CD8⁺ T cells infiltration in PC.

Study on the correlation between BMPR1B protein in sheep blood and reproductive performance

Sheep reproductive performance is one of the important economic traits in sheep farming. The bone morphogenetic protein receptor 1B (BMPR1B) gene and protein may play an important role in sheep fertility. This study was to investigate the association of blood BMPR1B protein expression with reproductive performance in sheep. Mongolian sheep with single and twin births and polytocous Small Tail Han sheep were selected due to differences in birth numbers. The BMPR1B mRNA in sheep blood was measured by a reverse transcription-polymerase chain reaction as well as the BMPR1B protein was measured by enzyme-linked immunosorbent assay in blood samples of Mongolian and Small Tail Han sheep. The results demonstrated that blood BMPR1B concentration in Mongolian sheep with twin birth was higher (P < 0.05) than Small Tail Han sheep and Mongolian sheep with single birth. The protein concentration in the anestrus season was higher (P < 0.045) than those in the estrus season for both Mongolian and Small Tail Han sheep. Moreover, BMPR1B concentration in Mongolian sheep increased (P < 0.05) at the age of 6 to 12 mo and that in Small Tail Han sheep increased (P < 0.05) at the age of 3 to 6 mo. The result indicates that the increase in BMPR1B protein concentrations in the blood of Mongolian ewes and Small Tail Han ewes may be beneficial to follicular development, but too high or too low of this blood protein concentration in Mongolian and Small Tail Han sheep is not conducive to ovulation.

SMAD-dependent signaling mediates morphogenetic protein 6-induced stimulation of connective tissue growth factor in luteinized human granulosa cells†

Connective tissue growth factor (also known as CTGF or CCN2) is a secreted matricellular protein that belongs to the CCN family. With wide-ranging biological activities and tissue expression patterns, CTGF plays a critical role in regulating various cellular functions. In the female reproductive system, CTGF is highly expressed in granulosa cells in growing ovarian follicles and is involved in the regulation of follicular development, ovulation, and luteal function. In the mammalian ovary, bone morphogenetic protein 6 (BMP6) is an important intraovarian modulator of follicular development. In this study, we demonstrated that BMP6 treatment significantly increased the expression of CTGF in both primary and immortalized human granulosa cells. Using both pharmacological inhibitors and Small interfering RNA-mediated knockdown approaches, we showed that ALK2 and ALK3 type I receptors are required for BMP6-induced cellular activities. Furthermore, this effect is most likely mediated by a Sma- and Mad-related protein (SMAD)-dependent pathway. Our studies provide novel insight into the molecular mechanisms by which an intraovarian growth factor affects the production of another factor via a paracrine effect in human granulosa cells.

ALK3-SMAD1/5 Signaling Mediates the BMP2-Induced Decrease in PGE2 Production in Human Endometrial Stromal Cells and Decidual Stromal Cells

BMP2 is a critical factor that is involved in the processes of embryo implantation and uterine decidualization. The expression of cyclooxygenase (COX) and subsequent prostaglandin E2 (PGE2) production are critical for successful pregnancy. However, it is not clear whether BMP2 can regulate the production of PG during endometrial decidualization. The aim of this study was to investigate the effects of BMP2 on COX-1 expression and PGE2 production as well as the underlying molecular mechanisms in the human endometrium. Immortalized human endometrial stromal cells (HESCs) and human decidual stromal cells (HDSCs) were used as the study model to investigate the effects of BMP2-induced cellular activities. Our results showed that BMP2 treatment significantly decreased PGE2 production by downregulating COX-1 expression in both human endometrial stromal and decidual stromal cells. Additionally, BMP2 induced an increase in the levels of phosphorylated SMAD1/5/8, and this effect was completely abolished by the addition of the inhibitors DMH-1 and dorsomorphin, but not by SB431542. Knocking down ALK3 completely reversed the BMP2-induced downregulation of COX-1. Moreover, concomitantly knocking down SMAD1 and SMAD5 completely reversed the BMP2-induced downregulation of COX-1. Our results indicated that BMP2 decreased PGE2 production by downregulating COX-1 expression, most likely through the ALK3/SMAD1-SMAD5 signaling pathway in human endometrial stromal and human decidual stromal cells. These findings deepen our understanding of the functional role of BMP2 in the regulation of endometrial decidualization in humans.

BMPR1A and BMPR1B Missense Mutations Cause Primary Ovarian Insufficiency

CONTEXT

Primary ovarian insufficiency (POI) is a frequently occurring disorder affecting approximately 1% of women under 40 years of age. POI, which is characterized by the premature depletion of ovarian follicles and elevated plasma levels of follicle-stimulating hormone, leads to infertility. Although various etiological factors have been described, including chromosomal abnormalities and gene mutations, most cases remain idiopathic.

OBJECTIVE

To identify and to functionally validate new sequence variants in 2 genes that play a key role in mammalian ovarian function, BMPR1A and BMPR1B (encoding for bone morphogenic protein receptor), leading to POI.

METHODS

The impact on bone morphogenic protein (BMP) signaling of BMPR1A and BMPR1B variants, previously identified by whole-exome sequencing on 69 women affected by isolated POI, was established by different in vitro functional experiments.

RESULTS

We demonstrate that the BMPR1A-p.Arg442His and BMPR1B-p.Phe272Leu variants are correctly expressed and located but lead to an impairment of downstream BMP signaling.

CONCLUSION

In accordance with infertility observed in mice lacking Bmpr1a in the ovaries and in Bmpr1b-/- mice, our results unveil, for the first time, a link between BMPR1A and BMPR1B variants and the origin of POI. We show that BMP signaling impairment through specific BMPR1A and BMPR1B variants is a novel pathophysiological mechanism involved in human POI. We consider that BMPR1A and BMPR1B variants constitute genetic biomarkers of the origin of POI and have clinical utility.

A novel mouse model of testicular granulosa cell tumors

STUDY QUESTION

What is the role of dysregulated transforming growth factor beta (TGFB) signaling in the development of sex cord-stromal tumors in the testis?

SUMMARY ANSWER

Overactivation of TGFB signaling results in the development of testicular tumors resembling granulosa cell tumors (GrCTs).

WHAT IS KNOWN ALREADY

In an earlier study, we demonstrated that constitutively active TGFB receptor 1 (TGFBR1) in ovarian somatic cells promotes the development of ovarian GrCTs. However, the consequence of dysregulation of TGFB signaling in the pathobiology of the testis, remains poorly defined.

STUDY DESIGN, SIZE, DURATION

To identify the impact of dysregulation of TGFB signaling on the testis, we generated mice with constitutive activation of TGFBR1 using anti-Mullerian hormone receptor type 2 (Amhr2)-Cre recombinase. The effect of constitutively active TGFBR1 on testis development and the timeline of testicular tumor formation were examined. We further investigated the molecular features of testicular tumors and determined the expression of beta-catenin (CTNNB1) known to be involved in testicular GrCT development.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Male mice with constitutive activation of TGFBR1 were examined at various developmental stages (i.e. from 1 week up to 6 months) along with controls. Testis samples were collected and processed for histological and molecular analyses, including haematoxylin and eosin (H and E) staining, real-time PCR, immunohistochemistry, immunofluorescence and western blotting. Immunostaining/immunoblotting and real-time PCR experiments were performed using at least three animals per genotype. Data are presented as mean ± SEM. Statistical significance was determined using unpaired two-tail t-test and reported when P value is <0.05.

MAIN RESULTS AND THE ROLE OF CHANCE

Mice harboring constitutively active TGFBR1 in the testes developed tumors resembling testicular GrCTs, a rare type of tumors in the testis. The formation of testicular tumors led to altered cell proliferation, loss of germ cells and defective spermatogenesis. Immunohistochemically, these tumors were positive for inhibin alpha (INHA), forkhead box O1 (FOXO1), and more importantly, forkhead box L2 (FOXL2), a protein specifically expressed in the ovary and required for normal granulosa cell differentiation and function. Consistent with the immunohistochemical findings, FOXL2 proteins were only detectable in testes of TGFBR1-CAAcre mice but not those of controls by western blotting, suggesting potential alteration of Sertoli cell fate. To explore mechanisms underlying the tumor-promoting effect of TGFBR1 overactivation, we examined the expression of CTNNB1. The results revealed increased expression of CTNNB1 in testicular tumors in TGFBR1-CAAcre mice. Collectively, this study uncovered tumorigenic function of enhanced TGFB signaling in the testis.

LARGE-SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This study was performed using mice, and the direct relevance of the experimental paradigm and findings to human testicular GrCTs awaits further investigation. Of note, constitutive activation of TGFBR1 was employed to enhance TGFB/SMAD signaling activity and may not be interpreted as the genetic cause of the disease.

WIDER IMPLICATIONS OF THE FINDINGS

This mouse model may prove to be a useful addition to the mouse genetics toolkit for GrCT research. Our finding that dysregulation of TGFB signaling results in the development of testicular GrCTs supports a common origin between Sertoli cells and granulosa cells, and highlights the paramount importance of balanced TGFB signaling in reproduction and development.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by the National Institutes of Health grant R03HD082416 from the Eunice Kennedy Shriver National Institute of Child Health & Human Development and the New Faculty Start-up Funds from Texas A&M University awarded to Q.L. The authors declare no competing interest.

Trio, a novel high fecundity allele: I. Transcriptome analysis of granulosa cells from carriers and noncarriers of a major gene for bovine ovulation rate

A major gene for bovine ovulation rate has been mapped to a 1.2 Mb region of chromosome 10. Screening of coding regions of positional candidate genes within this region failed to reveal a causative polymorphism, leading to the hypothesis that the phenotype results from differences in candidate gene expression rather than alteration of gene structure. This study tested differences in expression of positional candidate genes in granulosa cells between carriers and noncarriers of the high fecundity allele, as well as characterizing differences in the transcriptomic profile between genotypes. Five carriers and five noncarriers, female descendants of "Trio," a carrier of the high fecundity allele were initially used in an RNA-seq analysis of gene expression. Four of ten samples were contaminated with theca cells, so that six samples were used in the final analysis (three of each genotype). Of 14 973 genes expressed, 143 were differentially expressed (false discovery rate P < 0.05) in carriers versus noncarriers. Among the positional candidate genes, SMAD6 was 6.6-fold overexpressed in the carriers compared to noncarriers (P < 5 × 10-5). This result was replicated in an independent group of 12 females (7 carriers and 5 noncarriers) using quantitative real-time PCR; SMAD6 was 9.3-fold overexpressed in carriers versus noncarriers (P = 1.17 × 10-6). Association of overexpression of SMAD6, an inhibitor of the BMP/SMAD signaling pathway, with high ovulation rate corresponds well with disabling mutations in ligands (BMP15 and GDF9) and a receptor (BMPR1B) of this pathway that cause increased ovulation rate in sheep.

Uterine double-conditional inactivation of Smad2 and Smad3 in mice causes endometrial dysregulation, infertility, and uterine cancer

SMAD2 and SMAD3 are downstream proteins in the transforming growth factor-β (TGF β) signaling pathway that translocate signals from the cell membrane to the nucleus, bind DNA, and control the expression of target genes. While SMAD2/3 have important roles in the ovary, we do not fully understand the roles of SMAD2/3 in the uterus and their implications in the reproductive system. To avoid deleterious effects of global deletion, and given previous data showing redundant function of Smad2 and Smad3, a double-conditional knockout was generated using progesterone receptor-cre (Smad2/3 cKO) mice. Smad2/3 cKO mice were infertile due to endometrial hyperproliferation observed as early as 6 weeks of postnatal life. Endometrial hyperplasia worsened with age, and all Smad2/3 cKO mice ultimately developed bulky endometrioid-type uterine cancers with 100% mortality by 8 months of age. The phenotype was hormone-dependent and could be prevented with removal of the ovaries at 6 weeks of age but not at 12 weeks. Uterine tumor epithelium was associated with decreased expression of steroid biosynthesis genes, increased expression of inflammatory response genes, and abnormal expression of cell cycle checkpoint genes. Our results indicate the crucial role of SMAD2/3 in maintaining normal endometrial function and confirm the hormone-dependent nature of SMAD2/3 in the uterus. The hyperproliferation of the endometrium affected both implantation and maintenance of pregnancy. Our findings generate a mouse model to study the roles of SMAD2/3 in the uterus and serve to provide insight into the mechanism by which the endometrium can escape the plethora of growth regulatory proteins.

Distinct molecular pathways in ovarian endometrioid adenocarcinoma with concurrent endometriosis

Women with endometriosis, a benign growth of endometrial tissue outside the uterine cavity, are at increased risk of specific histotypes of epithelial ovarian cancer, such as ovarian endometrioid adenocarcinoma (OEA). Women with OEA who have endometriosis at time of surgical staging demonstrate improved clinical prognosis compared to women with OEA without evidence of endometriosis. However, the molecular contributions of the endometriotic tumor microenvironment to these ovarian cancers remain poorly understood. As a starting point, we used a platform for genome-wide transcriptomic profiling to compare specimens of OEA from women with and without concurrent endometriosis and benign reproductive tract tissues, including proliferative endometrium and typical and atypical endometrioma samples (n = 20). Principle component analysis revealed distinct clustering between benign and malignant samples as well as malignant samples with and without concurrent endometriosis. Examination of gene signatures revealed that OEA with concurrent endometriosis contained a unique molecular signature compared to OEA without concurrent endometriosis, distinguished by 682 unique genes differentially expressed (fold change < or >1.5, p < 0.01). Bioinformatic analysis of these differentially expressed gene products using ingenuity pathway analysis revealed activation of NFkB signaling, an inflammatory signaling pathway constitutively active in endometriosis. DAVID functional annotation clustering further revealed enrichment in RAS signaling as both cytoskeleton organization and GTPase regulator activity relied heavily on RAS protein signal transduction. Gene set enrichment analysis highlighted immune and inflammatory nodes involved in OEA with concurrent endometriosis. These observations provide novel resources for understanding molecular subtleties potentially involved in OEA within the context of the endometriotic tumor microenvironment.

Targeting GLI Transcription Factors in Cancer

Aberrant activation of hedgehog (Hh) signaling has been observed in a wide variety of tumors and accounts for more than 25% of human cancer deaths. Inhibitors targeting the Hh signal transducer Smoothened (SMO) are widely used and display a good initial efficacy in patients suffering from basal cell carcinoma (BCC); however, a large number of patients relapse. Though SMO mutations may explain acquired therapy resistance, a growing body of evidence suggests that the non-canonical, SMO-independent activation of the Hh pathway in BCC patients can also account for this adverse effect. In this review, we highlight the importance of glioma-associated oncogene (GLI) transcription factors (the main downstream effectors of the canonical and the non-canonical Hh cascade) and their putative role in the regulation of multiple oncogenic signaling pathways. Moreover, we discuss the contribution of the Hh signaling to malignant transformation and propose GLIs as central hubs in tumor signaling networks and thus attractive molecular targets in anti-cancer therapies.

The Dual Role of Bone Morphogenetic Proteins in Cancer

Bone morphogenetic proteins (BMPs) are a diverse class of molecules with over 20 growth factor proteins that belong to the transforming growth factor-β (TGF-β) family and are highly associated with bone formation and disease development. Aberrant expression of various BMPs has been reported in several cancer tissues. Biological function studies have elicited the dual role of BMPs in both cancer development and suppression. Furthermore, a variety of BMP antagonists, ligands, and receptors have been shown to reduce or enhance tumorigenesis and metastasis. Knockout mouse models of BMP signaling components have also revealed that the suppression of BMP signaling impairs cancer metastasis. Herein, we highlight the basic clinical background and involvement of BMPs in modulating cancer progression and their dynamic interactions (e.g., with microRNAs) in the tumor microenvironment in addition to their mutations and roles in chemoprevention. We also suggest that BMPs should be considered a powerful putative therapeutic target in tumorigenesis and bone metastasis.

Dullard deficiency causes hemorrhage in the adult ovarian follicles

In mammals, the ovarian follicles are regulated at least in part by bone morphogenetic protein (BMP) family members. Dullard (also known as Ctdnep1) gene encodes a phosphatase that suppresses BMP signaling by inactivating or degrading BMP receptors. Here we report that the Col1a1-Cre-induced Dullard mutant mice displayed hemorrhagic ovarian cysts, with red blood cells accumulated in the follicles, resulting in infertility. Cells expressing Cre driven by Col1a1 2.3-kb promoter and their descendants were found in granulosa cells in the ovary and in Sertoli cells in the testis. DullardmRNA was localized to granulosa cells in the ovary. Genes involved in steroid hormone genesis including Cyp11a1, Hsd3b1 and Star were reduced, whereas expression of Smad6 and Smad7, BMP-inducible inhibitory Smads, was up-regulated in the Dullard mutant ovaries. Tamoxifen-inducible Dullard deletion in the whole body using Rosa26-CreER mice also resulted in hemorrhagic ovarian cysts in 2 weeks, which was rescued by administration of LDN-193189, a chemical inhibitor of BMP receptor kinase, suggesting that the hemorrhage in the Dullard-deficient ovarian follicles might be caused by increased BMP signaling. Thus, we conclude that Dullard is essential for ovarian homeostasis at least in part via suppression of BMP signaling.

Involvement of Bone Morphogenetic Proteins (BMP) in the Regulation of Ovarian Function

Primordial germ cells migrate to the fetal gonads and proliferate during gestation to generate a fixed complement of primordial follicles, the so-called ovarian reserve. Primordial follicles comprise an oocyte arrested at the diplotene stage of meiosis, surrounded by a layer of pregranulosa cells. Activation of primordial follicles to grow beyond this arrested stage is of particular interest because, once activated, they are subjected to regulatory mechanisms involved in growth, selection, maturation, and ultimately, ovulation or atresia. The vast majority of follicles succumb to atresia and are permanently lost from the quiescent or growing pool of follicles. The bone morphogenetic proteins (BMPs), together with other intraovarian growth factors, are intimately involved in regulation of follicle recruitment, dominant follicle selection, ovulation, and atresia. Activation of primordial follicles appears to be a continuous process, and the number of small antral follicles at the beginning of the menstrual cycle provides an indirect indication of ovarian reserve. Continued antral follicle development during the follicular phase of the menstrual cycle is driven by follicle stimulating hormone (FSH) and luteinizing hormone (LH) in conjunction with many intraovarian growth factors and inhibitors interrelated in a complex web of regulatory balance. The BMP signaling system has a major intraovarian role in many species, including the human, in the generation of transcription factors that influence proliferation, steroidogenesis, cell differentiation, and maturation prior to ovulation, as well as formation of corpora lutea after ovulation. At the anterior pituitary level, BMPs also contribute to the regulation of gonadotrophin production.

The molecular mechanism of ovarian granulosa cell tumors

Over these years, more and more sex cord-stromal tumors have been reported. Granulosa cell tumor (GCT) is a rare tumor in ovaries, accounts for 2% to 5% of ovarian cancers. The main different feature of GCTs from other ovarian cancers is that GCTs can lead to abnormally secreted hormones (estrogen, inhibin and Müllerian inhibiting substance). The GCT is divided into two categories according to the age of patients, namely AGCT (adult granulosa cell tumor) and JGCT (Juvenile granulosa cell tumor). AGCT patients accounts for 95%. Although the pathogenesis is not clear, FOXL2 (Forkhead box L2) mutation was considered as the most critical factor in AGCT development. The current treatment is dominated by surgery. Target therapy remains in the adjuvant therapy stage, such as hormone therapy. During these years, other pathogenic factors were also explored, such as PI3K/AKT (phosphatidylinositol-3-kinase; serine/threonine kinase), TGF-β (Transforming growth factor beta) signaling pathway, Notch signaling pathway, GATA4 and VEGF (vascular endothelial growth factor). These factors and signaling pathway play important roles in GCT cell proliferation, apoptosis, or angiogenesis. The purpose of this review is to summarize the possible pathogenic factors and signaling pathways, which may shed lights on developing potential therapeutic targets for GCT.

Ovarian Follicular Theca Cell Recruitment, Differentiation, and Impact on Fertility: 2017 Update

The major goal of this review is to summarize recent exciting findings that have been published within the past 10 years that, to our knowledge, have not been presented in detail in previous reviews and that may impact altered follicular development in polycystic ovarian syndrome (PCOS) and premature ovarian failure in women. Specifically, we will cover the following: (1) mouse models that have led to discovery of the derivation of two precursor populations of theca cells in the embryonic gonad; (2) the key roles of the oocyte-derived factor growth differentiation factor 9 on the hedgehog (HH) signaling pathway and theca cell functions; and (3) the impact of the HH pathway on both the specification of theca endocrine cells and theca fibroblast and smooth muscle cells in developing follicles. We will also discuss the following: (1) other signaling pathways that impact the differentiation of theca cells, not only luteinizing hormone but also insulinlike 3, bone morphogenic proteins, the circadian clock genes, androgens, and estrogens; and (2) theca-associated vascular, immune, and fibroblast cells, as well as the cytokines and matrix factors that play key roles in follicle growth. Lastly, we will integrate what is known about theca cells from mouse models, human-derived theca cell lines from patients who have PCOS and patients who do not have PCOS, and microarray analyses of human and bovine theca to understand what pathways and factors contribute to follicle growth as well as to the abnormal function of theca.

Disruption of postnatal folliculogenesis and development of ovarian tumor in a mouse model with aberrant transforming growth factor beta signaling

BACKGROUND

Transforming growth factor beta (TGFB) superfamily signaling is implicated in the development of sex cord-stromal tumors, a category of poorly defined gonadal tumors. The aim of this study was to determine potential effects of dysregulated TGFB signaling in the ovary using Cre recombinase driven by growth differentiation factor 9 (Gdf9) promoter known to be expressed in oocytes.

METHODS

A mouse model containing constitutively active TGFBR1 (TGFBR1^CA) using Gdf9-iCre (termed TGFBR1-CA^G9Cre) was generated. Hematoxylin and eosin (H & E) staining, follicle counting, and immunohistochemistry and immunofluorescence analyses using antibodies directed to Ki67, forkhead box L2 (FOXL2), forkhead box O1 (FOXO1), inhibin alpha (INHA), and SRY (sex determining region Y)-box 9 were performed to determine the characteristics of the TGFBR1-CA^G9Cre ovary. Terminal deoxynucleotidyl transferase (TdT) labeling of 3'-OH ends of DNA fragments, real-time PCR, and western blotting were used to examine apoptosis, select gene expression, and TGFBR1 activation. RNAscope in situ hybridization was used to localize the expression of GLI-Kruppel family member GLI1 (Gli1) in ovarian tumor tissues.

RESULTS

TGFBR1-CA^G9Cre females were sterile. Sustained activation of TGFBR1 led to altered granulosa cell proliferation evidenced by high expression of Ki67. At an early age, these mice demonstrated follicular defects and development of ovarian granulosa cell tumors, which were immunoreactive for granulosa cell markers including FOXL2, FOXO1, and INHA. Further histochemical and molecular analyses provided evidence of overactivation of TGFBR1 in the granulosa cell compartment during ovarian pathogenesis in TGFBR1-CA^G9Cre mice, along with upregulation of Gli1 and Gli2 and downregulation of Tgfbr3 in ovarian tumor tissues.

CONCLUSIONS

These results reinforce the role of constitutively active TGFBR1 in promoting ovarian tumorigenesis in mice. The mouse model created in this study may be further exploited to define the cellular and molecular mechanisms of TGFB/activin downstream signaling in granulosa cell tumor development. Future studies are needed to test whether activation of TGFB/activin signaling contributes to the development of human granulosa cell tumors.

TGFβ superfamily signaling and uterine decidualization

Decidualization is an intricate biological process where extensive morphological, functional, and genetic changes take place in endometrial stromal cells to support the development of an implanting blastocyst. Deficiencies in decidualization are associated with pregnancy complications and reproductive diseases. Decidualization is coordinately regulated by steroid hormones, growth factors, and molecular and epigenetic mechanisms. Transforming growth factor β (TGFβ) superfamily signaling regulates multifaceted reproductive processes. However, the role of TGFβ signaling in uterine decidualization is poorly understood. Recent studies using the Cre-LoxP strategy have shed new light on the critical role of TGFβ signaling machinery in uterine decidualization. Herein, we focus on reviewing exciting findings from studies using both mouse genetics and in vitro cultured human endometrial stromal cells. We also delve into emerging mechanisms that underlie decidualization, such as non-coding RNAs and epigenetic modifications. We envision that future studies aimed at defining the interrelationship among TGFβ signaling circuitries and their potential interactions with epigenetic modifications/non-coding RNAs during uterine decidualization will open new avenues to treat pregnancy complications associated with decidualization deficiencies.

The TGF-β Family in the Reproductive Tract

The transforming growth factor β (TGF-β) family has a profound impact on the reproductive function of various organisms. In this review, we discuss how highly conserved members of the TGF-β family influence the reproductive function across several species. We briefly discuss how TGF-β-related proteins balance germ-cell proliferation and differentiation as well as dauer entry and exit in Caenorhabditis elegans. In Drosophila melanogaster, TGF-β-related proteins maintain germ stem-cell identity and eggshell patterning. We then provide an in-depth analysis of landmark studies performed using transgenic mouse models and discuss how these data have uncovered basic developmental aspects of male and female reproductive development. In particular, we discuss the roles of the various TGF-β family ligands and receptors in primordial germ-cell development, sexual differentiation, and gonadal cell development. We also discuss how mutant mouse studies showed the contribution of TGF-β family signaling to embryonic and postnatal testis and ovarian development. We conclude the review by describing data obtained from human studies, which highlight the importance of the TGF-β family in normal female reproductive function during pregnancy and in various gynecologic pathologies.

Combinatorial Signal Perception in the BMP Pathway

The bone morphogenetic protein (BMP) signaling pathway comprises multiple ligands and receptors that interact promiscuously with one another and typically appear in combinations. This feature is often explained in terms of redundancy and regulatory flexibility, but it has remained unclear what signal-processing capabilities it provides. Here, we show that the BMP pathway processes multi-ligand inputs using a specific repertoire of computations, including ratiometric sensing, balance detection, and imbalance detection. These computations operate on the relative levels of different ligands and can arise directly from competitive receptor-ligand interactions. Furthermore, cells can select different computations to perform on the same ligand combination through expression of alternative sets of receptor variants. These results provide a direct signal-processing role for promiscuous receptor-ligand interactions and establish operational principles for quantitatively controlling cells with BMP ligands. Similar principles could apply to other promiscuous signaling pathways.

Pathogenesis and treatment of adult-type granulosa cell tumor of the ovary

Adult-type granulosa cell tumor is a clinically and molecularly unique subtype of ovarian cancer. These tumors originate from the sex cord stromal cells of the ovary and represent 3-5% of all ovarian cancers. The majority of adult-type granulosa cell tumors are diagnosed at an early stage with an indolent prognosis. Surgery is the cornerstone for the treatment of both primary and relapsed tumor, while chemotherapy is applied only for advanced or non-resectable cases. Tumor stage is the only factor consistently associated with prognosis. However, every third of the patients relapse, typically in 4-7 years from diagnosis, leading to death in 50% of these patients. Anti-Müllerian Hormone and inhibin B are currently the most accurate circulating biomarkers. Adult-type granulosa cell tumors are molecularly characterized by a pathognomonic somatic missense point mutation 402C->G (C134W) in the transcription factor FOXL2. The FOXL2 402C->G mutation leads to increased proliferation and survival of granulosa cells, and promotes hormonal changes. Histological diagnosis of adult-type granulosa cell tumor is challenging, therefore testing for the FOXL2 mutation is crucial for differential diagnosis. Large international collaborations utilizing molecularly defined cohorts are essential to improve and validate new treatment strategies for patients with high-risk or relapsed adult-type granulosa cell tumor. Key Messages: Adult-type granulosa cell tumor is a unique ovarian cancer with an indolent, albeit unpredictable disease course. Adult-type granulosa cell tumors harbor a pathognomonic somatic missense mutation in transcription factor FOXL2. The key challenges in the treatment of patients with adult-type granulosa cell tumor lie in the identification and management of patients with high-risk or relapsed disease.

Increased bone morphogenetic protein-6 in follicular fluid and granulosa cells may correlate with fertilization and embryo quality in humans

Bone morphogenetic protein-6 (BMP-6), which is a member of the transforming growth factor-β superfamily, is associated with the regulation of bone development and various physiological processes. In the present study, the expression of BMP-6 in follicular fluid and granulosa cells (GCs) from pregnant and non-pregnant patients was explored. A total of 44 pregnant patients (pregnant group) and 36 non-pregnant patients (non-pregnant group) were recruited for the present study. The expression of BMP-6 was detected using western blotting and reverse transcription-quantitative polymerase chain reaction. The expression of BMP-6 was significantly higher at the protein level (P<0.01) in follicular fluid obtained from the pregnant group compared with that from the non-pregnant group. The mRNA and protein expression of BMP-6 in GCs were significantly upregulated in the pregnant group compared with the non-pregnant group (both P<0.01). These results suggest that high expression of BMP-6 in pregnant women may be a novel biomarker for the fertility process.

Follistatin is critical for mouse uterine receptivity and decidualization

Embryo implantation remains a significant challenge for assisted reproductive technology, with implantation failure occurring in ∼50% of in vitro fertilization attempts. Understanding the molecular mechanisms underlying uterine receptivity will enable the development of new interventions and biomarkers. TGFβ family signaling in the uterus is critical for establishing and maintaining pregnancy. Follistatin (FST) regulates TGFβ family signaling by selectively binding TGFβ family ligands and sequestering them. In humans, FST is up-regulated in the decidua during early pregnancy, and women with recurrent miscarriage have lower endometrial expression of FST during the luteal phase. Because global knockout of Fst is perinatal lethal in mice, we generated a conditional knockout (cKO) of Fst in the uterus using progesterone receptor-cre to study the roles of uterine Fst during pregnancy. Uterine Fst-cKO mice demonstrate severe fertility defects and deliver only 2% of the number of pups delivered by control females. In Fst-cKO mice, the uterine luminal epithelium does not respond properly to estrogen and progesterone signals and remains unreceptive to embryo attachment by continuing to proliferate and failing to differentiate. The uterine stroma of Fst-cKO mice also responds poorly to artificial decidualization, with lower levels of proliferation and differentiation. In the absence of uterine FST, activin B expression and signaling are up-regulated, and bone morphogenetic protein (BMP) signals are impaired. Our findings support a model in which repression of activin signaling by FST enables uterine receptivity by preserving critical BMP signaling.

Transposon insertional mutagenesis in mice identifies human breast cancer susceptibility genes and signatures for stratification

Despite concerted efforts to identify causal genes that drive breast cancer (BC) initiation and progression, we have yet to establish robust signatures to stratify patient risk. Here we used in vivo transposon-based forward genetic screening to identify potentially relevant BC driver genes. Integrating this approach with survival prediction analysis, we identified six gene pairs that could prognose human BC subtypes into high-, intermediate-, and low-risk groups with high confidence and reproducibility. Furthermore, we identified susceptibility gene sets for basal and claudin-low subtypes (21 and 16 genes, respectively) that stratify patients into three relative risk subgroups. These signatures offer valuable prognostic insight into the genetic basis of BC and allow further exploration of the interconnectedness of BC driver genes during disease progression.

Robust prognostic gene signatures and therapeutic targets are difficult to derive from expression profiling because of the significant heterogeneity within breast cancer (BC) subtypes. Here, we performed forward genetic screening in mice using Sleeping Beauty transposon mutagenesis to identify candidate BC driver genes in an unbiased manner, using a stabilized N-terminal truncated β-catenin gene as a sensitizer. We identified 134 mouse susceptibility genes from 129 common insertion sites within 34 mammary tumors. Of these, 126 genes were orthologous to protein-coding genes in the human genome (hereafter, human BC susceptibility genes, hBCSGs), 70% of which are previously reported cancer-associated genes, and ∼16% are known BC suppressor genes. Network analysis revealed a gene hub consisting of E1A binding protein P300 (EP300), CD44 molecule (CD44), neurofibromin (NF1) and phosphatase and tensin homolog (PTEN), which are linked to a significant number of mutated hBCSGs. From our survival prediction analysis of the expression of human BC genes in 2,333 BC cases, we isolated a six-gene-pair classifier that stratifies BC patients with high confidence into prognostically distinct low-, moderate-, and high-risk subgroups. Furthermore, we proposed prognostic classifiers identifying three basal and three claudin-low tumor subgroups. Intriguingly, our hBCSGs are mostly unrelated to cell cycle/mitosis genes and are distinct from the prognostic signatures currently used for stratifying BC patients. Our findings illustrate the strength and validity of integrating functional mutagenesis screens in mice with human cancer transcriptomic data to identify highly prognostic BC subtyping biomarkers.

Signaling Cross Talk between TGF-β/Smad and Other Signaling Pathways

Cytokines of the transforming growth factor β (TGF-β) family, including TGF-βs, bone morphogenic proteins (BMPs), activins, and Nodal, play crucial roles in embryonic development and adult tissue homeostasis by regulating cell proliferation, survival, and differentiation, as well as stem-cell self-renewal and lineage-specific differentiation. Smad proteins are critical downstream mediators of these signaling activities. In addition to regulating the transcription of direct target genes of TGF-β, BMP, activin, or Nodal, Smad proteins also participate in extensive cross talk with other signaling pathways, often in a cell-type- or developmental stage-specific manner. These combinatorial signals often produce context-, time-, and location-dependent biological outcomes that are critical for development. This review discusses recent progress in our understanding of the cross talk between Smad proteins and signaling pathways of Wnt, Notch, Hippo, Hedgehog (Hh), mitogen-activated protein (MAP), kinase, phosphoinositide 3-kinase (PI3K)-Akt, nuclear factor κB (NF-κB), and Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathways.

Signaling Cross Talk between TGF-β/Smad and Other Signaling Pathways

Cytokines of the transforming growth factor β (TGF-β) family, including TGF-βs, bone morphogenic proteins (BMPs), activins, and Nodal, play crucial roles in embryonic development and adult tissue homeostasis by regulating cell proliferation, survival, and differentiation, as well as stem-cell self-renewal and lineage-specific differentiation. Smad proteins are critical downstream mediators of these signaling activities. In addition to regulating the transcription of direct target genes of TGF-β, BMP, activin, or Nodal, Smad proteins also participate in extensive cross talk with other signaling pathways, often in a cell-type- or developmental stage-specific manner. These combinatorial signals often produce context-, time-, and location-dependent biological outcomes that are critical for development. This review discusses recent progress in our understanding of the cross talk between Smad proteins and signaling pathways of Wnt, Notch, Hippo, Hedgehog (Hh), mitogen-activated protein (MAP), kinase, phosphoinositide 3-kinase (PI3K)-Akt, nuclear factor κB (NF-κB), and Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathways.

The disparate origins of ovarian cancers: pathogenesis and prevention strategies

Ovarian cancer is the fifth cause of cancer-related death in women and comprises a histologically and genetically broad range of tumours, including those of epithelial, sex cord-stromal and germ cell origin. Recent evidence indicates that high-grade serous ovarian carcinoma, clear cell carcinoma and endometrioid carcinoma primarily arise from tissues that are not normally present in the ovary. These histogenetic pathways are informing risk-reduction strategies for the prevention of ovarian and ovary-associated cancers and have highlighted the importance of the seemingly unique ovarian microenvironment.

SMAD3 Activation: A Converging Point of Dysregulated TGF-Beta Superfamily Signaling and Genetic Aberrations in Granulosa Cell Tumor Development?

Ovarian granulosa cell tumors (GCTs) are rare gynecologic tumors in women. Due to the rarity and limited research efforts invested, the etiology of GCTs remains poorly defined. A landmark study has discovered the mutation of forkhead box L2 (FOXL2) as a genetic hallmark of adult GCTs in the human. However, our understanding of the role of cell signaling in GCT development is far from complete. Increasing lines of evidence highlight the importance of TGF-beta (TGFB) superfamily signaling in the pathogenesis of GCTs. This review draws on findings using genetically modified mouse models and human patient specimens and cell lines to reveal SMAD3 activation as a potentially key converging point of dysregulated TGFB superfamily signaling and genetic aberrations in GCT development. It is anticipated that deciphering the role of TGFB superfamily signaling cascades in ovarian tumorigenesis will help develop new therapeutic approaches for GCTs by targeting core signaling elements essential for tumor initiation, growth, and progression.

Constitutively active transforming growth factor β receptor 1 in the mouse ovary promotes tumorigenesis

Despite the well-established tumor suppressive role of TGFβ proteins, depletion of key TGFβ signaling components in the mouse ovary does not induce a growth advantage. To define the role of TGFβ signaling in ovarian tumorigenesis, we created a mouse model expressing a constitutively active TGFβ receptor 1 (TGFBR1) in ovarian somatic cells using conditional gain-of-function approach. Remarkably, these mice developed ovarian sex cord-stromal tumors with complete penetrance, leading to reproductive failure and mortality. The tumors expressed multiple granulosa cell markers and caused elevated serum inhibin and estradiol levels, reminiscent of granulosa cell tumors. Consistent with the tumorigenic effect, overactivation of TGFBR1 altered tumor microenvironment by promoting angiogenesis and enhanced ovarian cell proliferation, accompanied by impaired cell differentiation and dysregulated expression of critical genes in ovarian function. By further exploiting complementary genetic models, we substantiated our finding that constitutively active TGFBR1 is a potent oncogenic switch in mouse granulosa cells. In summary, overactivation of TGFBR1 drives gonadal tumor development. The TGFBR1 constitutively active mouse model phenocopies a number of morphological, hormonal, and molecular features of human granulosa cell tumors and are potentially valuable for preclinical testing of targeted therapies to treat granulosa cell tumors, a class of poorly defined ovarian malignancies.

Normal gonadotropin production and fertility in gonadotrope-specific Bmpr1a knockout mice

Pituitary follicle-stimulating hormone (FSH) synthesis is regulated by transforming growth factorβsuperfamily ligands, most notably the activins and inhibins. Bone morphogenetic proteins (BMPs) also regulate FSHβ subunit (Fshb) expression in immortalized murine gonadotrope-like LβT2 cells and in primary murine or ovine primary pituitary cultures. BMP2 signals preferentially via the BMP type I receptor, BMPR1A, to stimulate murine Fshb transcription in vitro Here, we used a Cre-lox approach to assess BMPR1A's role in FSH synthesis in mice in vivo Gonadotrope-specific Bmpr1a knockout animals developed normally and had reproductive organ weights comparable with those of controls. Knockouts were fertile, with normal serum gonadotropins and pituitary gonadotropin subunit mRNA expression. Cre-mediated recombination of the floxed Bmpr1a allele was efficient and specific, as indicated by PCR analysis of diverse tissues and isolated gonadotrope cells. Furthermore, BMP2 stimulation of inhibitor of DNA binding 3 expression was impaired in gonadotropes isolated from Bmpr1a knockout mice, confirming the loss of functional receptor protein in these cells. Treatment of purified gonadotropes with small-molecule inhibitors of BMPR1A (and the related receptors BMPR1B and ACVR1) suppressed Fshb mRNA expression, suggesting that an autocrine BMP-like molecule might regulate FSH synthesis. However, deletion of Bmpr1a and Acvr1 in cultured pituitary cells did not alter Fshb expression, indicating that the inhibitors had off-target effects. In sum, BMPs or related ligands acting via BMPR1A or ACVR1 are unlikely to play direct physiological roles in FSH synthesis by murine gonadotrope cells.

Insights into granulosa cell tumors using spontaneous or genetically engineered mouse models

Granulosa cell tumors (GCTs) are rare sex cord-stromal tumors that have been studied for decades. However, their infrequency has delayed efforts to research their etiology. Recently, mutations in human GCTs have been discovered, which has led to further research aimed at determining the molecular mechanisms underlying the disease. Mouse models have been important tools for studying GCTs, and have provided means to develop and improve diagnostics and therapeutics. Thus far, several genetically modified mouse models, along with one spontaneous mouse model, have been reported. This review summarizes the phenotypes of these mouse models and their applicability in elucidating the mechanisms of granulosa cell tumor development.

Repulsive Guidance Molecule b (RGMb) Is Dispensable for Normal Gonadal Function in Mice

Bone morphogenetic protein (BMP) signaling plays an important role in spermatogenesis and follicle development. Our previous studies have shown that repulsive guidance molecule b (RGMb, also known as Dragon) is a coreceptor that enhances BMP2 and BMP4 signaling in several cell types and that RGMb is expressed in spermatocytes and spermatids in the testis and in oocytes of the secondary follicles in the ovary. Here, we demonstrated that specific deletion of Rgmb in germ cells in the testis and ovary did not alter Smad1/5/8 phosphorylation, gonadal structures, and fertility. In addition, ovaries from postnatal global Rgmb knockout mice showed similar structures to the wild-type ovaries. Our results suggest that RGMb is not essential for normal gonadal function.

The soluble form of BMPRIB is a novel therapeutic candidate for treating bone related disorders

Bone morphogenetic proteins (BMPs) are multi-functional growth factors that belong to the TGF-beta superfamily. Recently, several soluble BMP receptors, such as ActRIIA-Fc, ActRIIB-Fc, and ALK1-Fc, are undergoing clinical trials. Both BMPRIA and BMPRIB are type I BMP receptors, and while BMPRIA-Fc has been reported to have bone-increasing properties, there have been no investigations concerning the biological functions of BMPRIB-Fc. Therefore, comparing the effects of BMPRIA-Fc and BMPRIB-Fc in vivo should be helpful in revealing the differences in biological function between BMPRIA and BMPRIB, and would also aid in the evaluation of BMPRIB-Fc as a therapeutic agent. Here, we produced Tg chimeras in which BMPRIA-Fc and BMPRIB-Fc proteins circulated at high concentrations (36.8–121.4 μg/mL). Both Tg chimeras showed a significant increase of bone volume and strength. Using histological analysis, adenoma of the glandular stomach was observed only in BMPRIA-Fc chimeras suggesting the tumorigenic activity of this protein. Administration of recombinant BMPRIB-Fc protein to normal mice also increased bone volumes. Finally, treatment with BMPRIB-Fc decreased the area of osteolytic regions in a mouse model of breast cancer metastasis. In conclusion, our data suggest that BMPRIB-Fc can be used for the treatment of bone-related disorders with a lower risk than BMPRIA-Fc.

Studying the Functions of TGF-β Signaling in the Ovary

In mammals, ovulation is a multistep physiological process that includes preovulatory follicle growth, oocyte meiotic maturation, cumulus-oocyte complex (COC) expansion, follicle rupture, and luteinization. TGF-β signaling pathway has multiple functions in mammalian ovary, as its complexity in ovarian function has been demonstrated by mouse models with knockouts of TGF-β receptors and SMADs. We describe the protocol that we use to study functions of TGF-β signaling pathway in follicle development and ovulation. Because total knockout of TGF-β pathway components often causes embryonic lethality, which prevents further investigation of these genes in ovarian functions, people have generated ovarian cell type-specific knockout mouse strains for TGF-β signaling pathway genes. These mouse models are also described.

BMP4 and BMP7 Suppress StAR and Progesterone Production via ALK3 and SMAD1/5/8-SMAD4 in Human Granulosa-Lutein Cells

Adequate production of progesterone by the corpus luteum is critical to the successful establishment of pregnancy. In animal models, bone morphogenetic protein (BMP) 4 and BMP7 have been shown to suppress either basal or gonadotropin-induced progesterone production, depending on the species examined. However, the effects of BMP4 and BMP7 on progesterone production in human granulosa cells are unknown. In the present study, we used immortalized (SVOG) and primary human granulosa-lutein cells to investigate the effects of BMP4 and BMP7 on steroidogenic acute regulatory protein (StAR) expression and progesterone production and to examine the underlying molecular mechanism. Treatment of primary and immortalized human granulosa cells with recombinant BMP4 or BMP7 decreased StAR expression and progesterone accumulation. In SVOG cells, the suppressive effects of BMP4 and BMP7 on StAR expression were blocked by pretreatment with inhibitors of activin receptor-like kinase (ALK)2/3/6 (dorsomorphin) or ALK2/3 (DMH1) but not ALK4/5/7 (SB-431542). Moreover, small interfering RNA-mediated depletion of ALK3, but not ALK2 or ALK6, reversed the effects of BMP4 and BMP7 on StAR expression. Likewise, BMP4- and BMP7-induced phosphorylation of SMAD 1/5/8 was reversed by treatment with DMH1 or small interfering RNA targeting ALK3. Knockdown of SMAD4, the essential common SMAD for BMP/TGF-β signaling, abolished the effects of BMP4 and BMP7 on StAR expression. Our results suggest that BMP4 and BMP7 down-regulate StAR and progesterone production via ALK3 and SMAD1/5/8-SMAD4 signaling in human granulosa-lutein cells.

Small molecule inhibitor of the bone morphogenetic protein pathway DMH1 reduces ovarian cancer cell growth

The bone morphogenetic protein (BMP) pathway belonging to the Transforming Growth Factor beta (TGFβ) family of secreted cytokines/growth factors is an important regulator of cancer. BMP ligands have been shown to play both tumor suppressive and promoting roles in human cancers. We have found that BMP ligands are amplified in human ovarian cancers and that BMP receptor expression correlates with poor progression-free-survival (PFS). Furthermore, active BMP signaling has been observed in human ovarian cancer tissue. We also determined that ovarian cancer cell lines have active BMP signaling in a cell autonomous fashion. Inhibition of BMP signaling with a small molecule receptor kinase antagonist is effective at reducing ovarian tumor sphere growth. Furthermore, BMP inhibition can enhance sensitivity to Cisplatin treatment and regulates gene expression involved in platinum resistance in ovarian cancer. Overall, these studies suggest targeting the BMP pathway as a novel source to enhance chemo-sensitivity in ovarian cancer.

FOXO1/3 and PTEN Depletion in Granulosa Cells Promotes Ovarian Granulosa Cell Tumor Development

The forkhead box (FOX), FOXO1 and FOXO3, transcription factors regulate multiple functions in mammalian cells. Selective inactivation of the Foxo1 and Foxo3 genes in murine ovarian granulosa cells severely impairs follicular development and apoptosis causing infertility, and as shown here, granulosa cell tumor (GCT) formation. Coordinate depletion of the tumor suppressor Pten gene in the Foxo1/3 strain enhanced the penetrance and onset of GCT formation. Immunostaining and Western blot analyses confirmed FOXO1 and phosphatase and tensin homolog (PTEN) depletion, maintenance of globin transcription factor (GATA) 4 and nuclear localization of FOXL2 and phosphorylated small mothers against decapentaplegic (SMAD) 2/3 in the tumor cells, recapitulating results we observed in human adult GCTs. Microarray and quantitative PCR analyses of mouse GCTs further confirmed expression of specific genes (Foxl2, Gata4, and Wnt4) controlling granulosa cell fate specification and proliferation, whereas others (Emx2, Nr0b1, Rspo1, and Wt1) were suppressed. Key genes (Amh, Bmp2, and Fshr) controlling follicle growth, apoptosis, and differentiation were also suppressed. Inhbb and Grem1 were selectively elevated, whereas reduction of Inha provided additional evidence that activin signaling and small mothers against decapentaplegic (SMAD) 2/3 phosphorylation impact GCT formation. Unexpectedly, markers of Sertoli/epithelial cells (SRY [sex determining region Y]-box 9/keratin 8) and alternatively activated macrophages (chitinase 3-like 3) were elevated in discrete subpopulations within the mouse GCTs, indicating that Foxo1/3/Pten depletion not only leads to GCTs but also to altered granulosa cell fate decisions and immune responses. Thus, analyses of the Foxo1/3/Pten mouse GCTs and human adult GCTs provide strong evidence that impaired functions of the FOXO1/3/PTEN pathways lead to dramatic changes in the molecular program within granulosa cells, chronic activin signaling in the presence of FOXL2 and GATA4, and tumor formation.

Estrogen mediated epithelial proliferation in the uterus is directed by stromal Fgf10 and Bmp8a

To define endometrial stromal-derived paracrine mediators that participate in estradiol-17β (E2)-induced epithelial proliferation, microarray analysis of gene expression was carried out in mouse uterine epithelial-stromal co-culture systems under the condition of E2 or vehicle (control). Our results demonstrated gene alteration by E2: in epithelial cells, we found up-regulation of 119 genes and down-regulation of 28 genes, while in stroma cells we found up-regulation of 144 genes and down-regulation of 184 genes. A functional enrichment analysis of the upregulated epithelial genes implicated them for proliferation, while upregulated stromal genes were associated with extracellular functions. Quantitative RT-PCR and in situ hybridization results confirmed differential gene expression in both cell cultures and ovariectomized uteri after the above treatments. Based on our identification of stromal secretory factors, we found evidence that suppression by siRNA specifically for Bmp8a and/or Fgf10 in the stromal layer caused significant inhibition of proliferation by E2 in the co-culture system, suggesting Bmp8a and Fgf10 act as paracrine mediators during E2-dependent control of uterine proliferation. The localization of receptors and receptor activation signaling in epithelial cells in both the co-culture system and uteri was consistent with their involvement in ligand-receptor signaling. Interestingly, loss of Bmp8a or Fgf10 also caused abrogation of E2-regulated epithelial receptor signaling in co-culture systems, suggesting that stroma-derived Fgf10 and Bmp8a are responsible for epithelial communication. Overall, stromal Fgf10 and Bmp8a serve as potential paracrine factors for E2-dependent regulation of epithelial proliferation in the uterus.