Allelic reduction of Dlx5 and Dlx6 results in early follicular depletion: a new mouse model of primary ovarian insufficiency

Rescue in vitro maturation using ovarian support cells of human oocytes from conventional stimulation cycles yields oocytes with improved nuclear maturation and transcriptomic resemblance to in vivo matured oocytes

PURPOSE

Determine if the gene expression profiles of ovarian support cells (OSCs) and cumulus-free oocytes are bidirectionally influenced by co-culture during in vitro maturation (IVM).

METHODS

Fertility patients aged 25 to 45 years old undergoing conventional ovarian stimulation donated denuded immature oocytes for research. Oocytes were randomly allocated to either OSC-IVM culture (intervention) or Media-IVM culture (control) for 24-28 h. The OSC-IVM culture condition was composed of 100,000 OSCs in suspension culture with human chorionic gonadotropin (hCG), recombinant follicle stimulating hormone (rFSH), androstenedione, and doxycycline supplementation. The Media-IVM control lacked OSCs and contained the same supplementation. A limited set of in vivo matured MII oocytes were donated for comparative evaluation. Endpoints consisted of MII formation rate, morphological and spindle quality assessment, and gene expression analysis compared to in vitro and in vivo controls.

RESULTS

OSC-IVM resulted in a statistically significant improvement in MII formation rate compared to the Media-IVM control, with no apparent effect on morphology or spindle assembly. OSC-IVM MII oocytes displayed a closer transcriptomic maturity signature to IVF-MII controls than Media-IVM control MII oocytes. The gene expression profile of OSCs was modulated in the presence of oocytes, displaying culture- and time-dependent differential gene expression during IVM.

CONCLUSION

The OSC-IVM platform is a novel tool for rescue maturation of human oocytes, yielding oocytes with improved nuclear maturation and a closer transcriptomic resemblance to in vivo matured oocytes, indicating a potential enhancement in oocyte cytoplasmic maturation. These improvements on oocyte quality after OSC-IVM are possibly occurring through bidirectional crosstalk of cumulus-free oocytes and ovarian support cells.

PITX2 regulates steroidogenesis in granulosa cells of dairy goat by the WNT/β-catenin pathway

Paired-like homeodomain transcription factor 2 (PITX2), a major driver of multiple tissue development, is a transcription factor that regulates gene expression in organisms. However, it is unknown if PITX2 regulates goat granulosa cell (GC) steroidogenesis. Therefore, we investigated the role and mechanism of PITX2 in GC steroidogenesis. In our study, PITX2 significantly facilitated the secretion level of estrogen and progesterone through increasing CYP11A1, CYP19A1, and STAR mRNA and protein expressions in GCs. Furthermore, PITX2 participated in the WNT pathway, enhancing the production of E₂ and P₄ in GCs. PITX2 in GCs increased the DVL-1 and CTNNB1 expression, involved in the WNT/β-catenin signaling pathway related to steroidogenesis. Moreover, GC steroidogenesis-related gene translation was decreased by CTNNB1-siRNA but enhanced when transfected with PITX2. PITX2 regulates secretion of E₂ and P₄ from GCs via the WNT/β-catenin pathway and alters GC proliferation and steroidogenesis. These findings will help understand the role of PITX2 in goat ovarian follicular development and oocyte maturation.

Application of Perinatal Derivatives in Ovarian Diseases

Reproductive diseases could lead to infertility and have implications for overall health, most importantly due to psychological, medical and socio-economic consequences for individuals and society. Furthermore, economical losses also occur in animal husbandry. In both human and veterinary medicine, hormonal and surgical treatments, as well as assisted reproductive technologies are used to cure reproductive disorders, however they do not improve fertility. With ovarian disorders being the main reproductive pathology in human and bovine, over the past 2 decades research has approached regenerative medicine in animal model to restore normal function. Ovarian pathologies are characterized by granulosa cell and oocyte apoptosis, follicular atresia, decrease in oocyte quality and embryonic development potential, oxidative stress and mitochondrial abnormalities, ultimately leading to a decrease in fertility. At current, application of mesenchymal stromal cells or derivatives thereof represents a valid strategy for regenerative purposes. Considering their paracrine/autocrine mode of actions that are able to regenerate injured tissues, trophic support, preventing apoptosis and fibrosis, promoting angiogenesis, stimulating the function and differentiation of endogenous stem cells and even reducing the immune response, are all important players in their future therapeutic success. Nevertheless, obtaining mesenchymal stromal cells (MSC) from adult tissues requires invasive procedures and implicates decreased cell proliferation and a reduced differentiation capacity with age. Alternatively, the use of embryonic stem cells as source of cellular therapeutic encountered several ethical concerns, as well as the risk of teratoma formation. Therefore, several studies have recently focussed on perinatal derivatives (PnD) that can be collected non-invasively and, most importantly, display similar characteristics in terms of regenerating-inducing properties, immune-modulating properties and hypo-immunogenicity. This review will provide an overview of the current knowledge and future perspectives of PnD application in the treatment of ovarian hypofunction.

Identification of differentially expressed genes associated with egg production in black-boned chicken

1. Muchuan black-bone chicken is well known in China for its meat quality and medicinal properties; however, its egg-laying performance is not ideal. To better understand the molecular mechanisms of black-boned chicken egg-laying, high-throughput RNA sequencing was performed to compare differences in the pituitary transcriptome between three high-rate (group H) and three low-rate (group L) egg production chickens. 2. In total, 171 differentially expressed genes (DEGs) were identified between the two groups, of which 113 were upregulated and 58 were downregulated in group L. Some of these genes are known to be related to hormone secretion or the regulation of reproductive processes; these include prolactin-releasing hormone (PRLH), distal-less homeobox 6 (DLX6), interferon regulatory factor 4 (IRF4), and cilia and flagella associated protein 69 (CFAP69). Notably, expression pattern analysis indicated that both PRLH and DLX6 may influence egg-laying performance. 3. The dataset provided a foundation for discovering important genes and pathways involved in the chicken egg-laying process, and may help to improve understanding of the molecular mechanisms of chicken reproduction.

Optimizing Nervous System-Specific Gene Targeting with Cre Driver Lines: Prevalence of Germline Recombination and Influencing Factors

The Cre-loxP system is invaluable for spatial and temporal control of gene knockout, knockin, and reporter expression in the mouse nervous system. However, we report varying probabilities of unexpected germline recombination in distinct Cre driver lines designed for nervous system-specific recombination. Selective maternal or paternal germline recombination is showcased with sample Cre lines. Collated data reveal germline recombination in over half of 64 commonly used Cre driver lines, in most cases with a parental sex bias related to Cre expression in sperm or oocytes. Slight differences among Cre driver lines utilizing common transcriptional control elements affect germline recombination rates. Specific target loci demonstrated differential recombination; thus, reporters are not reliable proxies for another locus of interest. Similar principles apply to other recombinase systems and other genetically targeted organisms. We hereby draw attention to the prevalence of germline recombination and provide guidelines to inform future research for the neuroscience and broader molecular genetics communities.

Dlx5 and Dlx6 expression in GABAergic neurons controls behavior, metabolism, healthy aging and lifespan

Dlx5 and Dlx6 encode two homeobox transcription factors expressed by developing and mature GABAergic interneurons. During development, Dlx5/6 play a role in the differentiation of certain GABAergic subclasses. Here we address the question of the functional role of Dlx5/6 in the mature central nervous system. First, we demonstrate that Dlx5 and Dlx6 are expressed by all subclasses of adult cortical GABAergic neurons. Then we analyze VgatΔDlx5-6 mice in which Dlx5 and Dlx6 are simultaneously inactivated in all GABAergic interneurons. VgatΔDlx5-6 mice present a behavioral pattern suggesting reduction of anxiety-like behavior and obsessive-compulsive activities, and a lower interest in nest building. Twenty-month-old VgatΔDlx5-6 animals have the same size as their normal littermates, but present a 25% body weight reduction associated with a marked decline in white and brown adipose tissue. Remarkably, both VgatΔDlx5-6/+ and VgatΔDlx5-6 mice present a 33% longer median survival. Hallmarks of biological aging such as motility, adiposity and coat conditions are improved in mutant animals. Our data imply that GABAergic interneurons can regulate healthspan and lifespan through Dlx5/6-dependent mechanisms. Understanding these regulations can be an entry point to unravel the processes through which the brain affects body homeostasis and, ultimately, longevity and healthy aging.

Comparative analysis of molecular signatures suggests the use of gabapentin for the management of endometriosis-associated pain

Background

It has been repetitively shown that the transcription factors DLX5 and DLX6 are drastically downregulated in endometriotic lesions when compared with eutopic endometrium. These findings suggest that regulatory cascades involving DLX5/6 might be at the origin of endometriosis symptoms such as chronic pelvic pain (CPP). We have shown that inactivation of Dlx5 and Dlx5/6 in the mouse uterus results in an endometrial phenotype reminiscent of endometriosis.

Methods

We focused on genes that present a similar deregulation in endometriosis and in Dlx5/6-null mice in search of new endometriosis targets.

Results

We confirmed a strong reduction of DLX5 expression in endometriosis implants. We identified a signature of 30 genes similarly deregulated in human endometriosis implants and in Dlx5/6-null mouse uteri, reinforcing the notion that the downregulation of Dlx5/6 is an early event in the progress of endometriosis. CACNA2D3, a component of the α2δ family of voltage-dependent calcium channel complex, was strongly overexpressed both in mutant mouse uteri and in endometriosis implants, were also CACNA2D1 and CACNA2D2, other members of the α2δ family involved in nociception, are upregulated.

Conclusion

Comparative analysis of gene expression signatures from endometriosis and mouse models showed that calcium channel subunits α2δ involved in nociception can be targets for the treatment of endometriosis-associated pain. CACNA2D3 has been associated with pain sensitization and heat nociception in animal models. In patients, CACNA2D3 variants were associated with reduced sensitivity to acute noxious stimuli. As α2δs were targets of gabapentinoid analgesics, the results suggested the use of these drugs for the treatment of endometriosis-associated pain. Indeed, recent small-scale clinical studies have shown that gabapentin could be effective in women with CPP. The findings of this study reinforce the need for a large definitive trial.

Involvement of FOXL2 and RSPO1 in Ovarian Determination, Development, and Maintenance in Mammals

In mammals, sex determination is a process through which the gonad is committed to differentiate into a testis or an ovary. This process relies on a delicate balance between genetic pathways that promote one fate and inhibit the other. Once the gonad is committed to the female pathway, ovarian differentiation begins and, depending on the species, is completed during gestation or shortly after birth. During this step, granulosa cell precursors, steroidogenic cells, and primordial germ cells start to express female-specific markers in a sex-dimorphic manner. The germ cells then arrest at prophase I of meiosis and, together with somatic cells, assemble into functional structures. This organization gives the ovary its definitive morphology and functionality during folliculogenesis. Until now, 2 main genetic cascades have been shown to be involved in female sex differentiation. The first is driven by FOXL2, a transcription factor that also plays a crucial role in folliculogenesis and ovarian fate maintenance in adults. The other operates through the WNT/CTNNB1 canonical pathway and is regulated primarily by R-spondin1. Here, we discuss the roles of FOXL2 and RSPO1/WNT/ CTNNB1 during ovarian development and homeostasis in different models, such as humans, goats, and rodents.

Direct evidence of allele equivalency at the Dlx5/6 locus

The retention of paralogous regulatory genes is a vertebrate hallmark and likely underpinned vertebrate origins. Dlx genes belong to a family of paralogous transcription factors whose evolutionary history of gene expansion and divergence is apparent from the gene synteny, shared exon-intron structure, and coding sequence homology found in extant vertebrate genomes. Dlx genes are expressed in a nested combination within the first pharyngeal arch and knockout studies in mice clearly point to a "Dlx code" that operates to define maxillary and mandibular position in the first arch. The nature of that code is not yet clear; an important goal for understanding Dlx gene function in both patterning and differentiation lies in distinguishing functional inputs that are paralog-specific (a qualitative model) versus Dlx family-generic (a quantitative model) and, in the latter case, the relative contribution made by each paralog. Here, multiple developmental deficiencies were identified in derivatives of the first pharyngeal arch in neonatal Dlx5/6(+/-) mice that resembled those seen in either paralog-specific null mutants. These data clearly demonstrate a substantial degree of allele equivalency and support a quantitative model of Dlx function during craniofacial morphogenesis. genesis 54:272-276, 2016. © 2016 Wiley Periodicals, Inc.

Dlx5 and Dlx6 control uterine adenogenesis during post-natal maturation: possible consequences for endometriosis

Dlx5 and Dlx6 are two closely associated homeobox genes which code for transcription factors involved in the control of steroidogenesis and reproduction. Inactivation of Dlx5/6 in the mouse results in a Leydig cell defect in the male and in ovarian insufficiency in the female. DLX5/6 are also strongly expressed by the human endometrium but their function in the uterus is unknown. The involvement of DLX5/6 in human uterine pathology is suggested by their strong downregulation in endometriotic lesions and upregulation in endometrioïd adenocarcinomas. We first show that Dlx5/6 expression begins in Müllerian ducts epithelia and persists then in the uterine luminal and glandular epithelia throughout post-natal maturation and in the adult. We then use a new mouse model in which Dlx5 and Dlx6 can be simultaneously inactivated in the endometrium using a Pgr(cre/+) allele. Post-natal inactivation of Dlx5/6 in the uterus results in sterility without any obvious ovarian involvement. The uteri of Pgr(cre/+); Dlx5/6(flox/flox) mice present very few uterine glands and numerous abnormally large and branched invaginations of the uterine lumen. In Dlx5/6 mutant uteri, the expression of genes involved in gland formation (Foxa2) and in epithelial remodelling during implantation (Msx1) is significantly reduced. Furthermore, we show that DLX5 is highly expressed in human endometrial glandular epithelium and that its expression is affected in endometriosis. We conclude that Dlx5 and Dlx6 expression determines uterine architecture and adenogenesis and is needed for implantation. Given their importance for female reproduction, DLX5 and DLX6 must be regarded as interesting targets for future clinical research.

Use of model systems to understand the etiology of fragile X-associated primary ovarian insufficiency (FXPOI)

Fragile X-associated primary ovarian insufficiency (FXPOI) is among the family of disorders caused by the expansion of a CGG repeat sequence in the 5' untranslated region of the X-linked gene FMR1. About 20% of women who carry the premutation allele (55 to 200 unmethylated CGG repeats) develop hypergonadotropic hypogonadism and cease menstruating before age 40. Some proportion of those who are still cycling show hormonal profiles indicative of ovarian dysfunction. FXPOI leads to subfertility and an increased risk of medical conditions associated with early estrogen deficiency. Little progress has been made in understanding the etiology of this clinically significant disorder. Understanding the molecular mechanisms of FXPOI requires a detailed knowledge of ovarian FMR1 mRNA and FMRP’s function. In humans, non-invasive methods to discriminate the mechanisms of the premutation on ovarian function are not available, thus necessitating the development of model systems. Vertebrate (mouse and rat) and invertebrate (Drosophila melanogaster) animal studies for the FMR1 premutation and ovarian function exist and have been instrumental in advancing our understanding of the disease phenotype. For example, rodent models have shown that FMRP is highly expressed in oocytes where it is important for folliculogenesis. The two premutation mouse models studied to date show evidence of ovarian dysfunction and, together, suggest that the long repeat in the transcript itself may have some pathological effect quite apart from any effect of the toxic protein. Further, ovarian morphology in young animals appears normal and the primordial follicle pool size does not differ from that of wild-type animals. However, there is a progressive premature decline in the levels of most follicle classes. Observations also include granulosa cell abnormalities and altered gene expression patterns. Further comparisons of these models are now needed to gain insight into the etiology of the ovarian dysfunction. Premutation model systems in non-human primates and those based on induced pluripotent stem cells show particular promise and will complement current models. Here, we review the characterization of the current models and describe the development and potential of the new models. Finally, we will discuss some of the molecular mechanisms that might be responsible for FXPOI.

Ecology drives intragenomic conflict over menopause

Menopause is the transition from reproductive to non-reproductive life well before natural death. Rather than involving a smooth, rapid change, it is normally preceded by a long period of erratic hormonal fluctuation that is accompanied by a plethora of unpleasant symptoms. Here, we (1) suggest that this turbulent period owes to conflict, between a woman's maternally inherited (MI) and paternally inherited (PI) genes, over the trade-off between reproduction and communal care; (2) perform a theoretical analysis to show that this conflict is resolved either through silencing or fluctuating expression of one of the genes; (3) highlight which of the symptoms preceding menopause may result from antagonistic co-evolution of MI and PI genes; (4) argue that ecological differences between ancestral human populations may explain the variability in menopause among different ethnic groups; (5) discuss how these insights may be used to inform family planning and cancer risk assessment based on a woman's ancestral background.

Genome-wide linkage in a highly consanguineous pedigree reveals two novel loci on chromosome 7 for non-syndromic familial Premature Ovarian Failure

Background

The human condition known as Premature Ovarian Failure (POF) is characterized by loss of ovarian function before the age of 40. A majority of POF cases are sporadic, but 10–15% are familial, suggesting a genetic origin of the disease. Although several causal mutations have been identified, the etiology of POF is still unknown for about 90% of the patients.

Methodology/Principal Findings

We report a genome-wide linkage and homozygosity analysis in one large consanguineous Middle-Eastern POF-affected family presenting an autosomal recessive pattern of inheritance. We identified two regions with a LOD_max of 3.26 on chromosome 7p21.1-15.3 and 7q21.3-22.2, which are supported as candidate regions by homozygosity mapping. Sequencing of the coding exons and known regulatory sequences of three candidate genes (DLX5, DLX6 and DSS1) included within the largest region did not reveal any causal mutations.

Conclusions/Significance

We detect two novel POF-associated loci on human chromosome 7, opening the way to the identification of new genes involved in the control of ovarian development and function.

Telling the story of XX sex reversal in the goat: highlighting the sex-crossroad in domestic mammals

The conditions for sex reversal in vertebrate species have been studied extensively and have highlighted numerous key factors involved in sex differentiation. We review here the history of the development of knowledge, referring to one example of complete female-to-male XX sex reversal associated with a polled phenotype in the goat. The results and hypotheses concerning this polled intersex syndrome (PIS) are then presented, firstly with respect to the transcriptional regulatory effects of the PIS mutation, and secondly regarding the role of the main ovarian-differentiating factor in this PIS locus, the FOXL2 gene.