Novel mutations in the TP63 gene are potentially associated with Müllerian duct anomalies

Implication of androgen receptor gene dysfunction in human Müllerian duct anomalies

BACKGROUND

Müllerian duct anomalies (MDAs) are congenital developmental disorders exhibiting as a variety of malformations of female reproductive tract. The identified etiology of MDAs is limited. The present study aimed to unravel the underlying genetic causes of MDAs.

METHODS

Rare variants in androgen receptor (AR) were called from the cohort consists of patients with MDAs and underwent whole exome sequencing (WES) at Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China. Sanger sequencing was used to confirm the causative genetic mutations. In silico analysis were used to classify the pathogenicity of each variant. Molecular modeling and simulations were conducted to investigate the conformational changes between the wild-type (WT) and mutant proteins.

RESULTS

A total of 3 rare heterozygous variants in AR from the MDAs cohort in our institution were identified, with unknown effects. All variants were missense mutations, including c.173A > T, c.558C > A and c.1208C > T, and were absent or rare in East Asian populations in Genome Aggregation Database and the Exome Aggregation Consortium Database. According to the American College of Medical Genetics and Genomics guidelines, c.1208C > T variant was classified as likely pathogenic, while the other two were variants of uncertain significance. During molecular dynamics simulations, WT and mutant proteins all reached stable status according to root-mean-square variance. Values of radius of gyration showed that Q58L and S186R protein would be more compact than WT, while the structure of A403V became looser. Despite, in comparison with WT, the number of hydrogen bonds increased in Q58L, while decreased in the other two variants. Furthermore, the solvent-accessible surface area diminished in Q58L and A403V while enlarged in S186R proteins, when compared with WT.

CONCLUSIONS

To our knowledge, this is the first report regarding the association of AR mutation and MDAs. The identification of these variants, predicted to damage the structure and function of AR protein, not only expanded the mutational spectrum of causative genes of MDAs, but provide novel molecular genetic reference for future studies.

TP63 gain-of-function mutations cause premature ovarian insufficiency by inducing oocyte apoptosis

The transcription factor p63 guards genome integrity in the female germline, and its mutations have been reported in patients with premature ovarian insufficiency (POI). However, the precise contribution of the TP63 gene to the pathogenesis of POI needs to be further determined. Here, in 1,030 Chinese patients with POI, we identified 6 heterozygous mutations of the TP63 gene that impaired the C-terminal transactivation-inhibitory domain (TID) of the TAp63α protein and resulted in tetramer formation and constitutive activation of the mutant proteins. The mutant proteins induced cell apoptosis by increasing the expression of apoptosis-inducing factors in vitro. We next introduced a premature stop codon and selectively deleted the TID of TAp63α in mice and observed rapid depletion of the p63+/ΔTID mouse oocytes through apoptosis after birth. Finally, to further verify the pathogenicity of the mutation p.R647C in the TID that was present in 3 patients, we generated p63+/R647C mice and also found accelerated oocyte loss, but to a lesser degree than in the p63+/ΔTID mice. Together, these findings show that TID-related variants causing constitutive activation of TAp63α lead to POI by inducing oocyte apoptosis, which will facilitate the genetic diagnosis of POI in patients and provide a potential therapeutic target for extending female fertility.

Modeling Endometrium Biology and Disease

The endometrium, lining the uterine lumen, is highly essential for human reproduction. Its exceptional remodeling plasticity, including the transformation process to welcome and nest the embryo, is not well understood. Lack of representative and reliable study models allowing the molecular and cellular mechanisms underlying endometrium development and biology to be deciphered is an important hurdle to progress in the field. Recently, powerful organoid models have been developed that not only recapitulate endometrial biology such as the menstrual cycle, but also faithfully reproduce diseases of the endometrium such as endometriosis. Moreover, single-cell profiling endeavors of the endometrium in health and disease, and of derived organoids, start to provide deeper insight into cellular complexity and expression specificities, and in resulting tissue processes. This granular portrayal will not only help in understanding endometrium biology and disease, but also in pinning down the tissue’s stem cells, at present not yet conclusively defined. Here, we provide a general overview of endometrium development and biology, and the efforts of modeling both the healthy tissue, as well as its key diseased form of endometriosis. The future of modeling and deciphering this key tissue, hidden inside the womb, looks bright.

Mutational analysis of the GATA4 gene in Chinese men with nonobstructive azoospermia

As a crucial transcription factor for spermatogenesis, GATA-binding protein 4 (GATA4) plays important roles in the functioning of Sertoli and Leydig cells. Conditional knockout of GATA4 in mice results in age-dependent testicular atrophy and loss of fertility. However, whether GATA4 is associated with human azoospermia has not been reported. Herein, we analyzed the GATA4 gene by direct sequencing of samples obtained from 184 Chinese men with idiopathic nonobstructive azoospermia (NOA). We identified a missense mutation (c.191G>A, p.G64E), nine single-nucleotide polymorphisms (SNPs), and one rare variant (c.^*84C>T) in the 3´ untranslated region (UTR). Functional studies demonstrated that the p.G64E mutation did not affect transactivation ability of GATA4 for spermatogenesis-related genes (claudin-11 and steroidogenic acute regulatory protein, Star), and the 3´ UTR rare variant c.^*84C>T did not generate microRNA-binding sites to repress GATA4 expression. To our knowledge, this is thefirst report to investigate the association between GATA4 and azoospermia; our results indicate that mutations in GATA4 may not be pathogenic for NOA in Chinese men.

The development of the human uterus: morphogenesis to menarche

There is emerging evidence that early uterine development in humans is an important determinant of conditions such as ontogenetic progesterone resistance, menstrual preconditioning, defective deep placentation and pre-eclampsia in young adolescents. A key observation is the relative infrequency of neonatal uterine bleeding and hormone withdrawal at birth. The origin of the uterus from the fusion of the two paramesonephric, or Müllerian, ducts was described almost 200 years ago. The uterus forms around the 10th week of foetal life. The uterine corpus and the cervix react differently to the circulating steroid hormones during pregnancy. Adult uterine proportions are not attained until after puberty. It is unclear if the endometrial microbiome and immune response-which are areas of growing interest in the adult-play a role in the early stages of uterine development. The aim is to review the phases of uterine development up until the onset of puberty in order to trace the origin of abnormal development and to assess current knowledge for features that may be linked to conditions encountered later in life. The narrative review incorporates literature searches of Medline, PubMed and Scopus using the broad terms individually and then in combination: uterus, development, anatomy, microscopy, embryology, foetus, (pre)-puberty, menarche, microbiome and immune cells. Identified articles were assessed manually for relevance, any linked articles and historical textbooks. We included some animal studies of molecular mechanisms. There are competing theories about the contributions of the Müllerian and Wolffian ducts to the developing uterus. Endometrium features are suggestive of an oestrogen effect at 16-20 weeks gestation. The discrepancy in the reported expression of oestrogen receptor is likely to be related to the higher sensitivity of more recent techniques. Primitive endometrial glands appear around 20 weeks. Features of progestogen action are expressed late in the third trimester. Interestingly, progesterone receptor expression is higher at mid-gestation than at birth when features of endometrial maturation are rare. Neonatal uterine bleeding occurs in around 5% of neonates. Myometrial differentiation progresses from the mesenchyme surrounding the endometrium at the level of the cervix. During infancy, the uterus and endometrium remain inactive. The beginning of uterine growth precedes the onset of puberty and continues for several years after menarche. Uterine anomalies may result from fusion defects or atresia of one or both Müllerian ducts. Organogenetic differentiation of Müllerian epithelium to form the endometrial and endocervical epithelium may be independent of circulating steroids. A number of genes have been identified that are involved in endometrial and myometrial differentiation although gene mutations have not been demonstrated to be common in cases of uterine malformation. The role, if any, of the microbiome in relation to uterine development remains speculative. Modern molecular techniques applied to rodent models have enhanced our understanding of uterine molecular mechanisms and their interactions. However, little is known about functional correlates or features with relevance to adult onset of uterine disease in humans. Prepubertal growth and development lends itself to non-invasive diagnostics such as ultrasound and MRI. Increased awareness of the occurrence of neonatal uterine bleeding and of the potential impact on adult onset disease may stimulate renewed research in this area.

Müllerian duct anomalies coincident with endometriosis: a review

The association between obstructed müllerian duct anomalies and endometriosis has been well established and the pathogenesis is attributed to the theory of retrograde menstruation. However, this relationship with endometriosis is less clear in women with unobstructed müllerian duct anomalies and in those with rudimentary uterine structures that lack functioning endometrial tissue. This article reviews the embryology, genetics, pathophysiology, and American Society for Reproductive Medicine (ASRM) classification for müllerian duct anomalies together with the genetics and pathophysiology of endometriosis to provide a framework for understanding the complex relationship between these two entities. Available published data examining the coexistence of endometriosis in relationship to müllerian duct anomalies, including studies that stratify this relationship according to specific classes of anomalies, are reviewed and organized. Awareness of the increased prevalence of endometriosis among patients with uterine anomalies, particularly those with outflow obstruction, may facilitate early diagnosis of endometriosis and subsequent intervention, with the potential to reverse disease symptoms and arrest disease progression.

Sequence variant in the CDC42BPB gene is potentially associated with Mullerian duct anomalies

AIM

Mullerian duct anomalies (MDA) are common female genital tract malformations. Genetic and environmental factors are important causes of MDA in women. Although many genes and mutations have been found to be associated with the pathogenesis of MDA, in most cases, the genetic pathogenic factors of MDA are still unknown.

METHODS

We first analyzed the three sisters using low coverage whole-genome sequencing. Then whole-exome sequencing was carried out in each patient. The identified sequence variant was confirmed by Sanger sequencing. In silico pathogenicity analysis and conservative analysis of the mutation site were also performed. Protein structural modeling was used to analyze the effect of the mutated amino acid.

RESULTS

We first analyzed the three sisters with septate uterus using low coverage whole-genome sequencing, but no possible pathogenic copy number variation was found. Then whole-exome sequencing was performed on the three sisters, and a rare homozygous variant, CDC42BPB:c.2012G>A:p.R671Q, was identified. All three patients were found with this variant. Sanger sequencing validated that this variant was segregated within the family. In silico pathogenicity analysis and conservative analysis of the mutation site suggested that the variant might be damaging. Protein structural analysis suggested that R671Q might weaken the electrostatic potential of this region, which may be a significant regulation target or protein interaction surface of CDC42BPB.

CONCLUSION

We demonstrated that CDC42BPB genetic variant might be potentially associated with the pathogenesis of MDA.