Abnormal epithelial cell polarity and ectopic epidermal growth factor receptor (EGFR) expression induced in Emx2 KO embryonic gonads

The single-cell chromatin landscape in gonadal cell lineage specification

Gonad development includes sex determination and divergent maturation of the testes and ovaries. Recent advances in measuring gene expression in single cells are providing new insights into this complex process. However, the underlying epigenetic regulatory mechanisms remain unclear. Here, we profiled chromatin accessibility in mouse gonadal cells of both sexes from embryonic day 11.5 to 14.5 using single-cell assay for transposase accessible chromatin by sequencing (scATAC-seq). Our results showed that individual cell types can be inferred by the chromatin landscape, and that cells can be temporally ordered along developmental trajectories. Integrative analysis of transcriptomic and chromatin-accessibility maps identified multiple putative regulatory elements proximal to key gonadal genes Nr5a1, Sox9 and Wt1. We also uncover cell type-specific regulatory factors underlying cell type specification. Overall, our results provide a better understanding of the epigenetic landscape associated with the progressive restriction of cell fates in the gonad.

Unveiling the roles of Sertoli cells lineage differentiation in reproductive development and disorders: a review

In mammals, gonadal somatic cell lineage differentiation determines the development of the bipotential gonad into either the ovary or testis. Sertoli cells, the only somatic cells in the spermatogenic tubules, support spermatogenesis during gonadal development. During embryonic Sertoli cell lineage differentiation, relevant genes, including WT1, GATA4, SRY, SOX9, AMH, PTGDS, SF1, and DMRT1, are expressed at specific times and in specific locations to ensure the correct differentiation of the embryo toward the male phenotype. The dysregulated development of Sertoli cells leads to gonadal malformations and male fertility disorders. Nevertheless, the molecular pathways underlying the embryonic origin of Sertoli cells remain elusive. By reviewing recent advances in research on embryonic Sertoli cell genesis and its key regulators, this review provides novel insights into sex determination in male mammals as well as the molecular mechanisms underlying the genealogical differentiation of Sertoli cells in the male reproductive ridge.

A comparative analysis of genes differentially expressed between rete testis cells and Sertoli cells of the mouse testis

The rete testis (RT) is a region of the mammalian testis that plays an important role in testicular physiology. The RT epithelium consists of cells sharing some well-known gene markers with supporting Sertoli cells (SCs). However, little is known about the differences in gene expression between these two cell populations. Here, we used fluorescence-activated cell sorting (FACS) to obtain pure cultures of neonatal RT cells and SCs and identified differentially expressed genes (DEGs) between these cell types using RNA sequencing (RNA-seq). We then compared our data with the RNA-seq data of other studies that examined RT cells and SCs of mice of different ages and generated a list of DEGs permanently upregulated in RT cells throughout testis development and in culture, which included 86 genes, and a list of 79 DEGs permanently upregulated in SCs. The analysis of studies on DMRT1 function revealed that nearly half of the permanent DEGs could be regulated by this SC upregulated transcription factor. We suggest that useful cell lineage markers and candidate genes for the specification of both RT cells and SCs may be present among these permanent DEGs.

Reconstituted ovaries self-assemble without an ovarian surface epithelium

Three-dimensional (3D) stem cell models of the ovary have the potential to benefit women's reproductive health research. One such model, the reconstituted ovary (rOvary) self-assembles with pluripotent stem cell-derived germ cells creating a 3D ovarian mimic competent to support the differentiation of functional oocytes inside follicles. In this study, we evaluated the cellular composition of the rOvary revealing the capacity to generate multiple follicles surrounded by NR2F2+ stroma cells. However, the rOvary does not develop a surface epithelium, the source of second-wave pre-granulosa cells, or steroidogenic theca. Therefore, the rOvary models represent the self-assembly of activated follicles in a pre-pubertal ovary poised but not yet competent for hormone production.

Cytogenomic Investigation of Syndromic Brazilian Patients with Differences of Sexual Development

BACKGROUND

Cytogenomic methods have gained space in the clinical investigation of patients with disorders/differences in sexual development (DSD). Here we evaluated the role of the SNP array in achieving a molecular diagnosis in Brazilian patients with syndromic DSD of unknown etiology.

METHODS

Twenty-two patients with DSD and syndromic features were included in the study and underwent SNP-array analysis.

RESULTS

In two patients, the diagnosis of 46,XX SRY + DSD was established. Additionally, two deletions were revealed (3q29 and Xp22.33), justifying the syndromic phenotype in these patients. Two pathogenic CNVs, a 10q25.3-q26.2 and a 13q33.1 deletion encompassing the FGFR2 and the EFNB2 gene, were associated with genital atypia and syndromic characteristics in two patients with 46,XY DSD. In a third 46,XY DSD patient, we identified a duplication in the 14q11.2-q12 region of 6.5 Mb associated with a deletion in the 21p11.2-q21.3 region of 12.7 Mb. In a 46,XY DSD patient with delayed neuropsychomotor development and congenital cataracts, a 12 Kb deletion on chromosome 10 was found, partially clarifying the syndromic phenotype, but not the genital atypia.

CONCLUSIONS

The SNP array is a useful tool for DSD patients, identifying the molecular etiology in 40% (2/5) of patients with 46,XX DSD and 17.6% (3/17) of patients with 46,XY DSD.

Genetic control of typical and atypical sex development

Sex development relies on the sex-specific action of gene networks to differentiate the bipotential gonads of the growing fetus into testis or ovaries, followed by the differentiation of internal and external genitalia depending on the presence or absence of hormones. Differences in sex development (DSD) arise from congenital alterations during any of these processes, and are classified depending on sex chromosomal constitution as sex chromosome DSD, 46,XY DSD or 46,XX DSD. Understanding the genetics and embryology of typical and atypical sex development is essential for diagnosing, treating and managing DSD. Advances have been made in understanding the genetic causes of DSD over the past 10 years, especially for 46,XY DSD. Additional information is required to better understand ovarian and female development and to identify further genetic causes of 46,XX DSD, besides congenital adrenal hyperplasia. Ongoing research is focused on the discovery of further genes related to typical and atypical sex development and, therefore, on improving diagnosis of DSD.

In vitro cellular reprogramming to model gonad development and its disorders

During embryonic development, mutually antagonistic signaling cascades determine gonadal fate toward a testicular or ovarian identity. Errors in this process result in disorders of sex development (DSDs), characterized by discordance between chromosomal, gonadal, and anatomical sex. The absence of an appropriate, accessible in vitro system is a major obstacle in understanding mechanisms of sex-determination/DSDs. Here, we describe protocols for differentiation of mouse and human pluripotent cells toward gonadal progenitors. Transcriptomic analysis reveals that the in vitro-derived murine gonadal cells are equivalent to embryonic day 11.5 in vivo progenitors. Using similar conditions, Sertoli-like cells derived from 46,XY human induced pluripotent stem cells (hiPSCs) exhibit sustained expression of testis-specific genes, secrete anti-Müllerian hormone, migrate, and form tubular structures. Cells derived from 46,XY DSD female hiPSCs, carrying an NR5A1 variant, show aberrant gene expression and absence of tubule formation. CRISPR-Cas9-mediated variant correction rescued the phenotype. This is a robust tool to understand mechanisms of sex determination and model DSDs.

Metzincin metalloproteases in PGC migration and gonadal sex conversion

Development of a functional gonad includes migration of primordial germ cells (PGCs), differentiations of somatic and germ cells, formation of primary follicles or spermatogenic cysts with somatic gonadal cells, development and maturation of gametes, and subsequent releasing of mature germ cells. These processes require extensive cellular and tissue remodeling, as well as broad alterations of the surrounding extracellular matrix (ECM). Metalloproteases, including MMPs (matrix metalloproteases), ADAMs (a disintegrin and metalloproteinases), and ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs), are suggested to have critical roles in the remodeling of the ECM during gonad development. However, few research articles and reviews are available on the functions and mechanisms of metalloproteases in remodeling gonadal ECM, gonadal development, or gonadal differentiation. Moreover, most studies focused on the roles of transcription and growth factors in early gonad development and primary sex determination, leaving a significant knowledge gap on how differentially expressed metalloproteases exert effects on the ECM, cell migration, development, and survival of germ cells during the development and differentiation of ovaries or testes. We will review gonad development with focus on the evidence of metalloprotease involvements, and with an emphasis on zebrafish as a model for studying gonadal sex differentiation and metalloprotease functions.

Reconstitution of reproductive organ system that produces functional oocytes

Reproductive organs have unique developmental and functional properties that enable them to manage both germ cell development and the endocrine system in a sex-dependent manner. Proper reconstitution of the reproductive organs, therefore, will contribute to a deeper understanding of the mechanisms underlying germ cell development and sex-determination. However, reproductive organs have not yet been systematically reconstituted from pluripotent stem cells. This is largely due to technical problems in the reconstitution of the germ cell and somatic cell lineages, which have very different developmental trajectories. Accordingly, faithful construction of reproductive organoids requires that the reconstitution and evaluation of these two different cell lineages be performed separately. Here, we update the state-of-the-art in the reconstitution of reproductive organoids that produce functional oocytes.

Transgenic Mouse Models to Study the Development and Maintenance of the Adrenal Cortex

The cortex of the adrenal gland is organized into concentric zones that produce distinct steroid hormones essential for body homeostasis in mammals. Mechanisms leading to the development, zonation and maintenance of the adrenal cortex are complex and have been studied since the 1800s. However, the advent of genetic manipulation and transgenic mouse models over the past 30 years has revolutionized our understanding of these mechanisms. This review lists and details the distinct Cre recombinase mouse strains available to study the adrenal cortex, and the remarkable progress total and conditional knockout mouse models have enabled us to make in our understanding of the molecular mechanisms regulating the development and maintenance of the adrenal cortex.

Gonadal Sex Differentiation and Ovarian Organogenesis along the Cortical-Medullary Axis in Mammals

In most mammals, the sex of the gonads is based on the fate of the supporting cell lineages, which arises from the proliferation of coelomic epithelium (CE) that surfaces on the bipotential genital ridge in both XY and XX embryos. Recent genetic studies and single-cell transcriptome analyses in mice have revealed the cellular and molecular events in the two-wave proliferation of the CE that produce the supporting cells. This proliferation contributes to the formation of the primary sex cords in the medullary region of both the testis and the ovary at the early phase of gonadal sex differentiation, as well as to that of the secondary sex cords in the cortical region of the ovary at the perinatal stage. To support gametogenesis, the testis forms seminiferous tubules in the medullary region, whereas the ovary forms follicles mainly in the cortical region. The medullary region in the ovary exhibits morphological and functional diversity among mammalian species that ranges from ovary-like to testis-like characteristics. This review focuses on the mechanism of gonadal sex differentiation along the cortical-medullary axis and compares the features of the cortical and medullary regions of the ovary in mammalian species.

Early Gonadal Development and Sex Determination in Mammal

Sex determination is crucial for the transmission of genetic information through generations. In mammal, this process is primarily regulated by an antagonistic network of sex-related genes beginning in embryonic development and continuing throughout life. Nonetheless, abnormal expression of these sex-related genes will lead to reproductive organ and germline abnormalities, resulting in disorders of sex development (DSD) and infertility. On the other hand, it is possible to predetermine the sex of animal offspring by artificially regulating sex-related gene expression, a recent research hotspot. In this paper, we reviewed recent research that has improved our understanding of the mechanisms underlying the development of the gonad and primordial germ cells (PGCs), progenitors of the germline, to provide new directions for the treatment of DSD and infertility, both of which involve manipulating the sex ratio of livestock offspring.

Metalloproteases in gonad formation and ovulation

Changes in expression or activation of various metalloproteases including matrix metalloproteases (Mmp), a disintegrin and metalloprotease (Adam) and a disintegrin and metalloprotease with thrombospondin motif (Adamts), and their endogenous inhibitors (tissue inhibitors of metalloproteases, Timp), have been shown to be critical for ovulation in various species from studies in past decades. Some of these metalloproteases such as Adamts1, Adamts9, Mmp2, and Mmp9 have also been shown to be regulated by luteinizing hormone (LH) and/or progestin, which are essential triggers for ovulation in all vertebrate species. Most of these metalloproteases also express broadly in various tissues and cells including germ cells and somatic gonad cells. Thus, metalloproteases likely play roles in gonad formation processes comprising primordial germ cell (PGC) migration, development of germ and somatic cells, and sex determination. However, our knowledge on the functions and mechanisms of metalloproteases in these processes in vertebrates is still lacking. This review will summarize our current knowledge on the metalloproteases in ovulation and gonad formation with emphasis on PGC migration and germ cell development.

Cis-Regulatory Control of Mammalian Sex Determination

Sex determination is the process by which an initial bipotential gonad adopts either a testicular or ovarian cell fate. The inability to properly complete this process leads to a group of developmental disorders classified as disorders of sex development (DSD). To date, dozens of genes were shown to play roles in mammalian sex determination, and mutations in these genes can cause DSD in humans or gonadal sex reversal/dysfunction in mice. However, exome sequencing currently provides genetic diagnosis for only less than half of DSD patients. This points towards a major role for the non-coding genome during sex determination. In this review, we highlight recent advances in our understanding of non-coding, cis-acting gene regulatory elements and discuss how they may control transcriptional programmes that underpin sex determination in the context of the 3-dimensional folding of chromatin. As a paradigm, we focus on the Sox9 gene, a prominent pro-male factor and one of the most extensively studied genes in gonadal cell fate determination.

The homeobox gene TGIF1 is required for chicken ovarian cortical development and generation of the juxtacortical medulla

During early embryogenesis in amniotic vertebrates, the gonads differentiate into either ovaries or testes. The first cell lineage to differentiate gives rise to the supporting cells: Sertoli cells in males and pre-granulosa cells in females. These key cell types direct the differentiation of the other cell types in the gonad, including steroidogenic cells. The gonadal surface epithelium and the interstitial cell populations are less well studied, and little is known about their sexual differentiation programs. Here, we show the requirement of the homeobox transcription factor gene TGIF1 for ovarian development in the chicken embryo. TGIF1 is expressed in the two principal ovarian somatic cell populations: the cortex and the pre-granulosa cells of the medulla. TGIF1 expression is associated with an ovarian phenotype in estrogen-mediated sex reversal experiments. Targeted misexpression and gene knockdown indicate that TGIF1 is required, but not sufficient, for proper ovarian cortex formation. In addition, TGIF1 is identified as the first known regulator of juxtacortical medulla development. These findings provide new insights into chicken ovarian differentiation and development, specifically cortical and juxtacortical medulla formation.

Generation of ovarian follicles from mouse pluripotent stem cells

Oocytes mature in a specialized fluid-filled sac, the ovarian follicle, which provides signals needed for meiosis and germ cell growth. Methods have been developed to generate functional oocytes from pluripotent stem cell-derived primordial germ cell-like cells (PGCLCs) when placed in culture with embryonic ovarian somatic cells. In this study, we developed culture conditions to recreate the stepwise differentiation process from pluripotent cells to fetal ovarian somatic cell-like cells (FOSLCs). When FOSLCs were aggregated with PGCLCs derived from mouse embryonic stem cells, the PGCLCs entered meiosis to generate functional oocytes capable of fertilization and development to live offspring. Generating functional mouse oocytes in a reconstituted ovarian environment provides a method for in vitro oocyte production and follicle generation for a better understanding of mammalian reproduction.

Regulation of sarcomagenesis by the empty spiracles homeobox genes EMX1 and EMX2

The EMX (Empty Spiracles Homeobox) genes EMX1 and EMX2 are two homeodomain gene members of the EMX family of transcription factors involved in the regulation of various biological processes, such as cell proliferation, migration, and differentiation, during brain development and neural crest migration. They play a role in the specification of positional identity, the proliferation of neural stem cells, and the differentiation of certain neuronal cell phenotypes. In general, they act as transcription factors in early embryogenesis and neuroembryogenesis from metazoans to higher vertebrates. The EMX1 and EMX2's potential as tumor suppressor genes has been suggested in some cancers. Our work showed that EMX1/EMX2 act as tumor suppressors in sarcomas by repressing the activity of stem cell regulatory genes (OCT4, SOX2, KLF4, MYC, NANOG, NES, and PROM1). EMX protein downregulation, therefore, induced the malignance and stemness of cells both in vitro and in vivo. In murine knockout (KO) models lacking Emx genes, 3MC-induced sarcomas were more aggressive and infiltrative, had a greater capacity for tumor self-renewal, and had higher stem cell gene expression and nestin expression than those in wild-type models. These results showing that EMX genes acted as stemness regulators were reproduced in different subtypes of sarcoma. Therefore, it is possible that the EMX genes could have a generalized behavior regulating proliferation of neural crest-derived progenitors. Together, these results indicate that the EMX1 and EMX2 genes negatively regulate these tumor-altering populations or cancer stem cells, acting as tumor suppressors in sarcoma.

The embryonic ontogeny of the gonadal somatic cells in mice and monkeys

In the early fetal stage, the gonads are bipotent and only later become the ovary or testis, depending on the genetic sex. Despite many studies examining how sex determination occurs from biopotential gonads, the spatial and temporal organization of bipotential gonads and their progenitors is poorly understood. Here, using lineage tracing in mice, we find that the gonads originate from a T⁺ primitive streak through WT1⁺ posterior intermediate mesoderm and appear to share origins anteriorly with the adrenal glands and posteriorly with the metanephric mesenchyme. Comparative single-cell transcriptomic analyses in mouse and cynomolgus monkey embryos reveal the convergence of the lineage trajectory and genetic programs accompanying the specification of biopotential gonadal progenitor cells. This process involves sustained expression of epithelial genes and upregulation of mesenchymal genes, thereby conferring an epithelial-mesenchymal hybrid state. Our study provides key resources for understanding early gonadogenesis in mice and primates.

Mesenteric and Retroperitoneal Mucinous Cystic Neoplasms: A Case Series

Aims. Mucinous cystic neoplasms (MCNs) are cystic neoplasms with mucinous epithelium surrounded by ovarian-like stroma. Extraovarian MCN occurring in the liver and pancreas have been well characterized. However, only rare case reports of MCN arising outside of these locations have been reported. MCNs arising in unusual locations should enter the differential diagnosis of mucinous intra-abdominal tumors and must be distinguished from more common mimics. Therefore, we aimed to examine a series of MCNs of the retroperitoneum and mesentery to characterize the clinicopathologic features of this entity. Methods and results. Seven MCNs arising in the abdominal mesentery or retroperitoneum were retrospectively identified. A clinicopathologic, histologic, and immunohistochemical (keratin 7, keratin 19, keratin 20, calretinin, inhibin-α, steroidogenic factor-1 (SF-1), estrogen receptor (ER), progesterone receptor (PR), PAX8, CDX2, and CD10) analysis was performed. All 7 MCNs were from females with a median age of 41 years old and a median size of 8 cm. All cases demonstrated mucinous with or without concomitant non-mucinous epithelium overlying spindle cell ovarian-like stroma. Luteinized cells were noted. The epithelium was positive for keratin 7 and keratin 19 in all 7 cases, while the stroma expressed ER, PR, and SF-1 in all cases stained. Calretinin was focally positive in the stroma of 3 of 7 cases, while inhibin-α was focally expressed in 5 of 6 cases. Conclusions. These results highlight the clinicopathologic, histologic, and immunophenotypic similarities between MCNs of the mesentery, retroperitoneum, pancreas, and liver. Overlapping features suggest a common histogenesis for all MCNs, which could include periductal fetal mesenchyme, aberrant migration of primordial germ cells, or abnormal differentiation or metaplasia of the embryonic coelomic epithelium.

Mapping molecular pathways for embryonic Sertoli cells derivation based on differentiation model of mouse embryonic stem cells

Background

Embryonic Sertoli cells (eSCs) have been known for playing important roles in male reproductive development system. In current studies, eSCs were mainly generated from induced intermediate mesoderm. The deriving mechanism of eSCs has been unclear so far. Therefore, this work was aimed to reveal the molecular pathways during derivation of eSCs.

Methods

In this scenario, a differentiation model from mouse embryonic stem cells (mESCs) to eSCs was established through spatiotemporal control of 5 key factors, Wilms tumor 1 homolog (Wt1), GATA binding protein 4 (Gata4), nuclear receptor subfamily 5, group A, member 1 (Nr5a1, i.e., Sf1), SRY (sex determining region Y)-box 9 (Sox9), doublesex, and mab-3 related transcription factor 1 (Dmrt1). To investigate the molecular mechanism, these key factors were respectively manipulated through a light-switchable (light-on) system, tetracycline-switchable (Tet-on) system, and CRISPR/Cas9 knock out (KO) system.

Results

Via the established approach, some embryonic Sertoli-like cells (eSLCs) were induced from mESCs and formed ring-like or tubular-like structures. The key factors were respectively manipulated and revealed their roles in the derivation of these eSLCs. Based on these results, some molecular pathways were mapped during the development of coelomic epithelial somatic cells to eSCs.

Conclusions

This differentiation model provided a high controllability of some key factors and brought a novel insight into the deriving mechanism of Sertoli cells.

Supplementary information

accompanies this paper at 10.1186/s13287-020-01600-2.

Testis Development

Production of sperm and androgens is the main function of the testis. This depends on normal development of both testicular somatic cells and germ cells. A genetic program initiated from the Y chromosome gene sex-determining region Y (SRY) directs somatic cell specification to Sertoli cells that orchestrate further development. They first guide fetal germ cell differentiation toward spermatogenic destiny and then take care of the full service to spermatogenic cells during spermatogenesis. The number of Sertoli cells sets the limits of sperm production. Leydig cells secrete androgens that determine masculine development. Testis development does not depend on germ cells; that is, testicular somatic cells also develop in the absence of germ cells, and the testis can produce testosterone normally to induce full masculinization in these men. In contrast, spermatogenic cell development is totally dependent on somatic cells. We herein review germ cell differentiation from primordial germ cells to spermatogonia and development of the supporting somatic cells. Testicular descent to scrota is necessary for normal spermatogenesis, and cryptorchidism is the most common male birth defect. This is a mild form of a disorder of sex differentiation. Multiple genetic reasons for more severe forms of disorders of sex differentiation have been revealed during the last decades, and these are described along with the description of molecular regulation of testis development.

High-throughput Exploration of the Network Dependent on AKT1 in Mouse Ovarian Granulosa Cells

The PI3K/AKT signaling pathway is known to regulate a broad range of cellular processes, and it is often altered in several types of cancers. Recently, somatic AKT1 mutations leading to a strong activation of this kinase have been reported in juvenile granulosa cell tumors. However, the molecular role of AKT1 in the supporting cell lineage of the ovary is still poorly understood. To get insights into its function in such cells, we depleted Akt1 in murine primary granulosa cells and assessed the molecular consequences at both the transcript and protein levels. We were able to corroborate the involvement of AKT1 in the regulation of metabolism, apoptosis, cell cycle, or cytoskeleton dynamics in this ovarian cell type. Consistently, we showed in established granulosa cells that depletion of Akt1 provoked altered directional persistent migration and increased its velocity. This study also allowed us to put forward new direct and indirect targets of the kinase. Indeed, a series of proteins involved in intracellular transport and mitochondrial physiology were significantly affected by Akt1 depletion. Using in silico analyses, we also propose a set of kinases and transcription factors that can mediate the action of AKT1 on the deregulated transcripts and proteins. Taken altogether, our results provide a resource of direct and indirect AKT1 targets in granulosa cells and may help understand its roles in this ovarian cell type.

High-throughput Exploration of the Network Dependent on AKT1 in Mouse Ovarian Granulosa Cells

The PI3K/AKT signaling pathway is known to regulate a broad range of cellular processes, and it is often altered in several types of cancers. Recently, somatic AKT1 mutations leading to a strong activation of this kinase have been reported in juvenile granulosa cell tumors. However, the molecular role of AKT1 in the supporting cell lineage of the ovary is still poorly understood. To get insights into its function in such cells, we depleted Akt1 in murine primary granulosa cells and assessed the molecular consequences at both the transcript and protein levels. We were able to corroborate the involvement of AKT1 in the regulation of metabolism, apoptosis, cell cycle, or cytoskeleton dynamics in this ovarian cell type. Consistently, we showed in established granulosa cells that depletion of Akt1 provoked altered directional persistent migration and increased its velocity. This study also allowed us to put forward new direct and indirect targets of the kinase. Indeed, a series of proteins involved in intracellular transport and mitochondrial physiology were significantly affected by Akt1 depletion. Using in silico analyses, we also propose a set of kinases and transcription factors that can mediate the action of AKT1 on the deregulated transcripts and proteins. Taken altogether, our results provide a resource of direct and indirect AKT1 targets in granulosa cells and may help understand its roles in this ovarian cell type.

Differentiation roadmap of embryonic Sertoli cells derived from mouse embryonic stem cells

Background

Embryonic Sertoli cells (eSCs) play an important role in sex determination and in male gonad development which makes them a very useful cell type for therapeutic applications. However, the deriving mechanism of Sertoli cells has been unclear and challenging to create a large number of quality eSCs. Therefore, this study aimed to create the eSCs induced from mouse embryonic stem (mES) cells by regulating defined factors and to explore the relevant regulatory mechanism.

Methods

Six inducing factors, Sry, Sox9, SF1, WT1, GATA4, and Dmrt1, were respectively transduced into mES cells by lentiviral infection according to the experimental design. The test groups were identified by development stage-specific markers, AMH, Emx2, SF1, and FasL, using flow cytometry. Induced eSCs were determined by FasL and AMH biomarkers under immunofluorescence, immunocytochemistry, and flow cytometry. Moreover, the pluripotency markers, gonad development-related markers, epithelial markers and mesenchymal markers in test groups were transcriptionally determined by qPCR.

Results

In this study, the co-overexpression of all the six factors effectively produced a large population of eSCs from mES cells in 35 days of culturing. These eSCs were capable of forming tubular-like and ring-like structures with functional performance. The results of flow cytometry indicated that the upregulation of GATA4 and WT1 contributed to the growth of somatic cells in the coelomic epithelium regarded as the main progenitor cells of eSCs. Whereas, SF1 facilitated the development of eSC precursor cells, and Sry and Sox9 promoted the determination of male development. Moreover, the overexpression of Dmrt1 was essential for the maintenance of eSCs and some of their specific surface biomarkers such as FasL. The cellular morphology, biomarker identification, and transcriptomic analysis aided in exploring the regulatory mechanism of deriving eSCs from mES cells.

Conclusion

Conclusively, we have elucidated a differentiation roadmap of eSCs derived from mES cells with a relevant regulatory mechanism. Through co-overexpression of all these six factors, a large population of eSCs was successfully induced occupying 24% of the whole cell population (1 × 10⁵ cells/cm²). By adopting this approach, a mass of embryonic Sertoli cells can be generated for the purpose of co-culture technique, organ transplantation, gonadal developmental and sex determination researches.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1180-6) contains supplementary material, which is available to authorized users.

Molecular and genetic characterization of partial masculinization in embryonic ovaries grafted into male nude mice

In most of mammalian embryos, gonadal sex differentiation occurs inside the maternal uterus before birth. In several fetal ovarian grafting experiments using male host mice, an experimental switch from the maternal intrauterine to male-host environment gradually induces partial masculinization of the grafted ovaries even under the wild-type genotype. However, either host-derived factors causing or molecular basis underlying this masculinization of the fetal ovaries are not clear. Here, we demonstrate that ectopic appearance of SOX9-positive Sertoli cell-like cells in grafted ovaries was mediated by the testosterone derived from the male host. Neither Sox8 nor Amh activity in the ovarian tissues is essential for such ectopic appearance of SOX9-positive cells. The transcriptome analyses of the grafted ovaries during this masculinization process showed early downregulation of pro-ovarian genes such as Irx3, Nr0b1/Dax1, Emx2, and Fez1/Lzts1 by days 7–10 post-transplantation, and subsequent upregulation of several pro-testis genes, such as Bhlhe40, Egr1/2, Nr4a2, and Zc3h12c by day 20, leading to a partial sex reversal with altered expression profiles in one-third of the total numbers of the sex-dimorphic pre-granulosa and Sertoli cell-specific genes at 12.5 dpc. Our data imply that the paternal testosterone exposure is partially responsible for the sex-reversal expression profiles of certain pro-ovarian and pro-testis genes in the fetal ovaries in a temporally dependent manner.

Mice doubly deficient in Six4 and Six5 show ventral body wall defects reproducing human omphalocele

Omphalocele is a human congenital anomaly in ventral body wall closure and may be caused by impaired formation of the primary abdominal wall (PAW) and/or defects in abdominal muscle development. Here, we report that mice doubly deficient in homeobox genes Six4 and Six5 showed the same ventral body wall closure defects as those seen in human omphalocele. SIX4 and SIX5 were localized in surface ectodermal cells and somatic mesoderm-derived mesenchymal and coelomic epithelial cells (CECs) in the PAW. Six4^-/-;Six5^-/- fetuses exhibited a large omphalocele with protrusion of both the liver and intestine, or a small omphalocele with protrusion of the intestine, with complete penetrance. The umbilical ring of Six4^-/-;Six5^-/- embryos was shifted anteriorly and its lateral size was larger than that of normal embryos at the E11.5 stage, before the onset of myoblast migration into the PAW. The proliferation rates of surface ectodermal cells in the left and right PAW and somatic mesoderm-derived cells in the right PAW were lower in Six4^-/-;Six5^-/- embryos than those of wild-type embryos at E10.5. The transition from CECs of the PAW to rounded mesothelial progenitor cells was impaired and the inner coelomic surface of the PAW was relatively smooth in Six4^-/-;Six5^-/- embryos at E11.25. Furthermore, Six4 overexpression in CECs of the PAW promoted ingression of CECs. Taken together, our results suggest that Six4 and Six5 are required for growth and morphological change of the PAW, and the impairment of these processes is linked to the abnormal positioning and expansion of the umbilical ring, which results in omphalocele.

Mesothelial to mesenchyme transition as a major developmental and pathological player in trunk organs and their cavities

The internal organs embedded in the cavities are lined by an epithelial monolayer termed the mesothelium. The mesothelium is increasingly implicated in driving various internal organ pathologies, as many of the normal embryonic developmental pathways acting in mesothelial cells, such as those regulating epithelial-to-mesenchymal transition, also drive disease progression in adult life. Here, we summarize observations from different animal models and organ systems that collectively point toward a central role of epithelial-to-mesenchymal transition in driving tissue fibrosis, acute scarring, and cancer metastasis. Thus, drugs targeting pathways of mesothelium’s transition may have broad therapeutic benefits in patients suffering from these diseases.

Tim Koopmans and Yuval Rinkevich review recent findings linking the mesothelium’s embryonic programs that drive epithelial-to-mesenchyme transition with adult pathologies, such as fibrosis, acute scarring, and cancer metastasis. They highlight new avenues for drug development that would target pathways of the mesothelium’s mesenchymal transition.

At the Crossroads of Fate-Somatic Cell Lineage Specification in the Fetal Gonad

The reproductive endocrine systems are vastly different between males and females. This sexual dimorphism of the endocrine milieu originates from sex-specific differentiation of the somatic cells in the gonads during fetal life. Most gonadal somatic cells arise from the adrenogonadal primordium. After separation of the adrenal and gonadal primordia, the gonadal somatic cells initiate sex-specific differentiation during gonadal sex determination with the specification of the supporting cell lineages: Sertoli cells in the testis vs granulosa cells in the ovary. The supporting cell lineages then facilitate the differentiation of the steroidogenic cell lineages, Leydig cells in the testis and theca cells in the ovary. Proper differentiation of these cell types defines the somatic cell environment that is essential for germ cell development, hormone production, and establishment of the reproductive tracts. Impairment of lineage specification and function of gonadal somatic cells can lead to disorders of sexual development (DSDs) in humans. Human DSDs and processes for gonadal development have been successfully modeled using genetically modified mouse models. In this review, we focus on the fate decision processes from the initial stage of formation of the adrenogonadal primordium in the embryo to the maintenance of the somatic cell identities in the gonads when they become fully differentiated in adulthood.

Mesothelial-mesenchymal transitions in embryogenesis

Most animals develop coelomic cavities lined by an epithelial cell layer called the mesothelium. Embryonic mesothelial cells have the ability to transform into mesenchymal cells which populate many developing organs contributing to their connective and vascular tissues, and also to organ-specific cell types. Furthermore, embryonic mesothelium and mesothelial-derived cells produce essential signals for visceral morphogenesis. We review the most relevant literature about the mechanisms regulating the embryonic mesothelial-mesenchymal transition, the developmental fate of the mesothelial-derived cells and other functions of the embryonic mesothelium, such as its contribution to the establishment of left-right visceral asymmetries or its role in limb morphogenesis.

The molecular pathways underlying early gonadal development

The body of knowledge surrounding reproductive development spans the fields of genetics, anatomy, physiology and biomedicine, to build a comprehensive understanding of the later stages of reproductive development in humans and animal models. Despite this, there remains much to learn about the bi-potential progenitor structure that the ovary and testis arise from, known as the genital ridge (GR). This tissue forms relatively late in embryonic development and has the potential to form either the ovary or testis, which in turn produce hormones required for development of the rest of the reproductive tract. It is imperative that we understand the genetic networks underpinning GR development if we are to begin to understand abnormalities in the adult. This is particularly relevant in the contexts of disorders of sex development (DSDs) and infertility, two conditions that many individuals struggle with worldwide, with often no answers as to their aetiology. Here, we review what is known about the genetics of GR development. Investigating the genetic networks required for GR formation will not only contribute to our understanding of the genetic regulation of reproductive development, it may in turn open new avenues of investigation into reproductive abnormalities and later fertility issues in the adult.

Assembling the jigsaw puzzle: CBX2 isoform 2 and its targets in disorders/differences of sex development

BACKGROUND

One of the defining moments of human life occurs early during embryonic development, when individuals sexually differentiate into either male or female. Perturbation of this process can lead to disorders/differences of sex development (DSD). Chromobox protein homolog 2 (CBX2) has two distinct isoforms, CBX2.1 and CBX2.2: the role of CBX2.1 in DSD has been previously established, yet to date the function of the smaller isoform CBX2.2 remains unknown.

METHODS

The genomic DNA of two 46,XY DSD patients was analysed using whole exome sequencing. Furthermore, protein/DNA interaction studies were performed using DNA adenine methyltransferase identification (DamID) to identify putative binding partners of CBX2. Finally, in vitro functional studies were used to elucidate the effect of wild-type and variant CBX2.2 on selected downstream targets.

RESULTS

Here, we describe two patients with features of DSD i.e. atypical external genitalia, perineal hypospadias and no palpable gonads, each patient carrying a distinct CBX2.2 variant, p.Cys132Arg (c.394T>C) and p.Cys154fs (c.460delT). We show that both CBX2.2 variants fail to regulate the expression of genes essential for sexual development, leading to a severe 46,XY DSD defect, likely because of a defective expression of EMX2 in the developing gonad.

CONCLUSION

Our study indicates a distinct function of the shorter form of CBX2 and by identifying several of its unique targets, can advance our understanding of DSD pathogenesis and ultimately DSD diagnosis and management.

Epigenetic regulation of mammalian sex determination

Regulation of gene expression without changing the DNA sequence is governed by epigenetic mechanisms. Epigenetic regulation is important for changing chromatin structure in response to environmental cues as well as maintaining chromatin structure after cell division. The epigenetic machinery can reversibly change chromatin function, allowing a wide variety of biological processes in multicellular organisms to be controlled. Epigenetic regulation ensures spatial and temporal accuracy of the expression of developmentally regulated genes. So far, few studies have focused on the relationship between epigenetic regulation and mammalian sex development, despite this being an interesting area of research. Sex development consists of three sequential stages: the undifferentiated stage, gonadal differentiation into testes or ovaries, and differentiation of internal and external genitalia. Some genetic studies have revealed that epigenetic regulation is required for proper gonadal differentiation in mice. Particularly, the epigenetic machinery plays an integral part in sex determination, which is the first step of gonadal differentiation. Mammalian sex determination is triggered by activation of the mammalian sex-determining gene, Sry, in a spatially and temporally accurate manner. Several studies have demonstrated that expression of Sry is controlled not only by specific transcription factors but also by the epigenetic machinery. Here, we focus on the epigenetic regulation of Sry expression.

Fibroblast growth factor signaling is required for early somatic gonad development in zebrafish

The vertebrate ovary and testis develop from a sexually indifferent gonad. During early development of the organism, primordial germ cells (the gamete lineage) and somatic gonad cells coalesce and begin to undergo growth and morphogenesis to form this bipotential gonad. Although this aspect of development is requisite for a fertile adult, little is known about the genetic regulation of early gonadogenesis in any vertebrate. Here, we provide evidence that fibroblast growth factor (Fgf) signaling is required for the early growth phase of a vertebrate bipotential gonad. Based on mutational analysis in zebrafish, we show that the Fgf ligand 24 (Fgf24) is required for proliferation, differentiation, and morphogenesis of the early somatic gonad, and as a result, most fgf24 mutants are sterile as adults. Additionally, we describe the ultrastructural elements of the early zebrafish gonad and show that distinct somatic cell populations can be identified soon after the gonad forms. Specifically, we show that fgf24 is expressed in an epithelial population of early somatic gonad cells that surrounds an inner population of mesenchymal somatic gonad cells that are in direct contact with the germ cells, and that fgf24 is required for stratification of the somatic tissue. Furthermore, based on gene expression analysis, we find that differentiation of the inner mesenchymal somatic gonad cells into functional cell types in the larval and early juvenile-stage gonad is dependent on Fgf24 signaling. Finally, we argue that the role of Fgf24 in zebrafish is functionally analogous to the role of tetrapod FGF9 in early gonad development.

The Battle of the Sexes: Human Sex Development and Its Disorders

The process of sexual differentiation is central for reproduction of almost all metazoan and therefore for maintenance of practically all multicellular organisms. In sex development we can distinguish two different processes: First, sex determination is the developmental decision that directs the undifferentiated embryo into a sexually dimorphic individual. In mammals, sex determination equals gonadal development. The second process known as sex differentiation takes place once the sex determination decision has been made through factors produced by the gonads that determine the development of the phenotypic sex. Most of the knowledge on the factors involved in sexual development came from animal models and from studies of cases in whom the genetic or the gonadal sex does not match the phenotypical sex, i.e., patients affected by disorders of sex development (DSD). Generally speaking, factors influencing sex determination are transcriptional regulators, whereas factors important for sex differentiation are secreted hormones and their receptors. This review focuses on the factors involved in gonadal determination, and whenever possible, references on the "prismatic" clinical cases are given.

Critical role of Emx2 in the pluripotency – differentiation transition in male gonocytes via regulation of FGF9/NODAL pathway

Emx2 deletion impairs the growth and maintenance of the genital ridge. However, its role in subsequent germ cell differentiation during embryonic stages is unknown. Using a tamoxifen-inducible Cre-loxP mouse model (Emx2flox/flox, Cre-ERTM, hereafter called as Emx2 knockdown), we showed that germ cell differentiation was impaired in Emx2-knockdown testes. Representative characteristics of male germ cell differentiation, including a reduced ability to form embryonic germ (EG) cell colonies in vitro, down-regulation of pluripotency markers and G1/G0 arrest, did not occur in Emx2-knockdown testes. Furthermore, FGF9 and NODAL signalling occurred at abnormally high levels in Emx2-knockdown testes. Both blocking FGF9 signalling with SU5402 and inhibiting NODAL signalling with SB431542 allowed germ cells from Emx2-knockdown testes to differentiate in vitro. Therefore, EMX2 in somatic cells is required to trigger germ cell differentiation in XY foetuses, posterior to its previously reported role in the growth and maintenance of the genital ridge.

Hearing loss, coloboma and left ventricular enlargement in a boy with an interstitial 10q26 deletion

Distal deletion of the long arm of chromosome 10 with breakpoints mapped at 10q26 is a well-recognized contiguous genomic disorder. A wide spectrum of clinical findings is seen in affected individuals and the common clinical features include craniofacial dysmorphia, developmental delay, intellectual disability, hypotonia, cardiovascular defects, and urogenital malformations. We report herein on a male patient with a 5.5 Mb interstitial deletion of 10q26.11q2613 and compare his clinical presentation to previously reported cases. Apart from characteristic phenotypes seen in 10q26 deletion syndrome, he presents with colobomas and left ventricle enlargement. These are cardiovascular and ophthalmological findings that have not been described in prior cases. © 2016 Wiley Periodicals, Inc.

Methods for the Study of Gonadal Development

Current knowledge on gonadal development and sex determination is the product of many decades of research involving a variety of scientific methods from different biological disciplines such as histology, genetics, biochemistry, and molecular biology. The earliest embryological investigations, followed by the invention of microscopy and staining methods, were based on histological examinations. The most robust development of histological staining techniques occurred in the second half of the nineteenth century and resulted in structural descriptions of gonadogenesis. These first studies on gonadal development were conducted on domesticated animals; however, currently the mouse is the most extensively studied species. The next key point in the study of gonadogenesis was the advancement of methods allowing for the in vitro culture of fetal gonads. For instance, this led to the description of the origin of cell lines forming the gonads. Protein detection using antibodies and immunolabeling methods and the use of reporter genes were also invaluable for developmental studies, enabling the visualization of the formation of gonadal structure. Recently, genetic and molecular biology techniques, especially gene expression analysis, have revolutionized studies on gonadogenesis and have provided insight into the molecular mechanisms that govern this process. The successive invention of new methods is reflected in the progress of research on gonadal development.

The Gonadal Supporting Cell Lineage and Mammalian Sex Determination: The Differentiation of Sertoli and Granulosa Cells

The supporting cell lineage plays a crucial role in nurturing the development of germ cells in the adult gonad. Sertoli cells in the testis support the progression of spermatogonial stem cells through meiosis to the production of motile spermatozoa. Granulosa cells, meanwhile, are a critical component of the ovarian follicle that produces the mature oocyte. It is a distinctive feature of the embryonic gonad that at least some of the supporting cells are derived from a single sexually bipotential precursor lineage. It is the commitment of this somatic lineage to either the Sertoli or granulosa cell fate that defines sex determination. In this chapter we review what is known about the key molecules responsible for this lineage decision in the developing mammalian gonads, relying primarily on data from studies of mice and humans. We focus on recent advances in our understanding of the mutually antagonistic interactions of testis- and ovary-determining pathways and their complexity as revealed by genetic analyses. For the sake of simplicity, we will deal with supporting cells in testis and ovary development in separate sections, but numerous points of contact exist between these accounts of gonadogenesis in male and female embryos, primarily due to the aforementioned mutual antagonisms. The final section will offer a brief synthesis of these organ-specific overviews and a summary of the key themes that emerge in this review of supporting cell differentiation in mammalian sex determination.

Early Development of the Gonads: Origin and Differentiation of the Somatic Cells of the Genital Ridges

The earliest manifestation of gonadogenesis in vertebrates is the formation of the genital ridges. The genital ridges form through the transformation of monolayer coelomic epithelium into a cluster of somatic cells. This process depends on increased proliferation of coelomic epithelium and disintegration of its basement membrane, which is foreshadowed by the expression of series of regulatory genes. The earliest expressed gene is Gata4, followed by Sf1, Lhx9, Emx2, and Cbx2. The early genital ridge is a mass of somatic SF1-positive cells (gonadal precursor cells) that derive from proliferating coelomic epithelium. Primordial germ cells (PGCs) immigrate to the coelomic epithelium even in the absence of genital ridges, e.g., in mouse null mutants for Gata4. And conversely, the PGCs are not required for the formation of the genital ridges. After reaching genital ridges, the PGCs become enclosed by somatic cells derived from coelomic epithelium. Subsequently, the expression of sex-determining genes begins and the bipotential gonads differentiate into either testes or ovaries. Gonadal precursor cells, derived from coelomic epithelium, give rise to the somatic supporting cells such as Sertoli cells, follicular cells, and probably also peritubular myoid and steroidogenic cells.

Mesonephric Cell Migration into the Gonads and Vascularization Are Processes Crucial for Testis Development

Testis morphogenesis requires the integration and reorganization of multiple cell types from several sources, one of the more notable being the mesonephric-derived cell population. One of the earliest sex-specific morphogenetic events in the gonad is a wave of endothelial cell migration from the mesonephros that is crucial for (1) partitioning the gonad into domains for testis cords, (2) providing the vasculature of the testis, and (3) signaling to cells both within the gonad and beyond it to coordinately regulate testis development. In addition to endothelial cell migration, there is evidence that precursors of peritubular myoid cells migrate from the mesonephros, an event which is also important for testis cord architecture. Investigation of the mesonephric cell migration event has utilized histology, lineage tracing with mouse genetic markers, and many studies of the signaling molecules/pathways involved. Some of the more well-studied signaling molecules involved include vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and neurotrophins. In this chapter, the morphogenetic events, relevant signaling pathways, mechanisms underlying the migration, and the role of the migratory cells within the testis will be discussed. Overall, the migration of mesonephric cells into the early testis is indispensable for its development and future functionality.

Identification and expression of the target gene emx2 of miR-26a and miR-26b in Paralichthys olivaceus

MicroRNAs (miRNAs) can regulate specific gene expression by binding to target mRNA further involution to diverse biological processes. Our previous miRNA sequencing showed that pol-miR-26a and pol-miR-26b have a sex-biased expression in ovary and testis of Paralichthys olivaceus (P. olivaceus). And the gene empty spiracles homeobox 2 (emx2) was proposed to be a candidate target by bioinformatics prediction. In this study, we cloned the P. olivaceus emx2 cDNA, including a coding region of 741 bp and a 3'-untranslated region (UTR) of 912 bp and the 5'-UTR of 12 bp. The Emx2 protein is highly conserved and especially its homeodomain region is 100% identical from teleosts to mammals. Real-time PCR results showed that the emx2 is not only highly expressed in embryonic neurula stage and adult brain but also has abundant expression in adult gonad, moreover, it exhibits higher expression in ovary than testis. To determine the relationship between emx2 and miRNAs, a luciferase reporter assay was performed and verified that the emx2 is a common target gene of pol-miR-26a and pol-miR-26b. These data thus helps further clarify that miR-26a and miR-26b are involved in regulating gonad development partially through its target on emx2 expression in P. olivaceus.

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.

Cell fate commitment during mammalian sex determination

The gonads form bilaterally as bipotential organs that can develop as testes or ovaries. All secondary sex characteristics that we associate with 'maleness' or 'femaleness' depend on whether testes or ovaries form. The fate of the gonads depends on a cell fate decision that occurs in a somatic cell referred to as the 'supporting cell lineage'. Once supporting cell progenitors commit to Sertoli (male) or granulosa (female) fate, they propagate this decision to the other cells within the organ. In this review, we will describe what is known about the bipotential state of somatic and germ cell lineages in the gonad and the transcriptional and antagonistic signaling networks that lead to commitment, propagation, and maintenance of testis or ovary fate.

Celsr1 is required for the generation of polarity at multiple levels of the mouse oviduct

The oviduct is an important organ in reproduction where fertilization occurs, and through which the fertilized eggs are carried to the uterus in mammals. This organ is highly polarized, where the epithelium forms longitudinal folds along the ovary-uterus axis, and the epithelial multicilia beat towards the uterus to transport the ovulated ova. Here, we analyzed the postnatal development of mouse oviduct and report that multilevel polarities of the oviduct are regulated by a planar cell polarity (PCP) gene, Celsr1. In the epithelium, Celsr1 is concentrated in the specific cellular boundaries perpendicular to the ovary-uterus axis from postnatal day 2. We found a new feature of cellular polarity in the oviduct - the apical surface of epithelial cells is elongated along the ovary-uterus axis. In Celsr1-deficient mice, the ciliary motion is not orchestrated along the ovary-uterus axis and the transport ability of beating cilia is impaired. Epithelial cells show less elongation and randomized orientation, and epithelial folds show randomized directionality and ectopic branches in the mutant. Our mosaic analysis suggests that the geometry of epithelial cells is primarily regulated by Celsr1 and as a consequence the epithelial folds are aligned. Taken together, we reveal the characteristics of the multilevel polarity formation processes in the mouse oviduct epithelium and suggest a novel function of the PCP pathway for proper tissue morphogenesis.

Emx2 expression levels in NSCs modulate astrogenesis rates by regulating EgfR and Fgf9

Generation of astrocytes within the developing cerebral cortex is a tightly regulated process, initiating at low level in the middle of neuronogenesis and peaking up after its completion. Astrocytic outputs depend on two primary factors: progression of multipotent precursors toward the astroglial lineage and sizing of the astrogenic proliferating pool. The aim of this study was to investigate the role of the Emx2 homeobox gene in the latter process. We addressed this issue by combined gain- and loss-of-function methods, in vivo as well as in primary cultures of cortico-cerebral precursors. We found that Emx2 overexpression in cortico-cerebral stem cells shrinked the proliferating astrogenic pool, resulting in a severe reduction of the astroglial outcome. We showed that this was caused by EgfR and Fgf9 downregulation and that both phenomena originated from exaggerated Bmp signaling and Sox2 repression. Finally, we provided evidence that in vivo temporal progression of Emx2 levels in cortico-cerebral multipotent precursors contributes to confine the bulk of astrogenesis to postnatal life. Emx2 regulation of astrogenesis adds to a number of earlier developmental processes mastered by this gene. It points to Emx2 as a new promising tool for controlling reactive astrogliosis and optimizing cell-based designs for brain repair.