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Summary: Various human diseases and pregnancy-related disorders reflect endometrial dysfunction. However, rodent models do not share fundamental biological processes with the human endometrium, such as spontaneous decidualization, and no existing human cell cultures recapitulate the cyclic interactions between endometrial stromal and epithelial compartments necessary for decidualization and implantation. Here we report a protocol differentiating human pluripotent stem cells into endometrial stromal fibroblasts (PSC-ESFs) that are highly pure and able to decidualize. Coculture of PSC-ESFs with placenta-derived endometrial epithelial cells generated organoids used to examine stromal-epithelial interactions. Cocultures exhibited specific endometrial markers in the appropriate compartments, organization with cell polarity, and hormone responsiveness of both cell types. Furthermore, cocultures recapitulate a central feature of the human decidua by cyclically responding to hormone withdrawal followed by hormone retreatment. This advance enables mechanistic studies of the cyclic responses that characterize the human endometrium.

Evolutionary changes in the anatomy and physiology of the female reproductive system underlie the origins and diversification of pregnancy in Eutherian (“Placental”) mammals. This developmental and evolutionary history constrains normal physiological functions and biases the ways in which dysfunction contributes to reproductive trait diseases and adverse pregnancy outcomes. Here, we show that gene expression changes in the human endometrium during pregnancy are associated with the evolution of human-specific traits and pathologies of pregnancy. We found that hundreds of genes gained or lost endometrial expression in the human lineage. Among these are genes that may contribute to human-specific maternal-fetal communication (HTR2B) and maternal-fetal immunotolerance (PDCD1LG2) systems, as well as vascular remodeling and deep placental invasion (CORIN). These data suggest that explicit evolutionary studies of anatomical systems complement traditional methods for characterizing the genetic architecture of disease. We also anticipate our results will advance the emerging synthesis of evolution and medicine (“evolutionary medicine”) and be a starting point for more sophisticated studies of the maternal-fetal interface. Furthermore, the gene expression changes we identified may contribute to the development of diagnostics and interventions for adverse pregnancy outcomes.

The developmental origins and evolutionary histories of cell types, tissues and organ systems contribute to the ways in which their dysfunction leads to disease. In mammals for example, the nature and extent of maternal-fetal interactions, how those interactions develop, and their evolutionary history likely influence diseases of pregnancy such as infertility and preterm birth. Here we show genes that evolved to be expressed at the maternal-fetal interface in Eutherian (‘Placental’) mammals play essential roles in the evolution of pregnancy and are associated with immune system disorders and preterm birth. Among these genes is the transcription factor HAND2, which suppresses estrogen signaling, an innovation of Eutherians, thereby allowing blastocyst implantation. We found that HAND2 is dynamically expressed in the decidua throughout the menstrual cycle and pregnancy, gradually decreasing to reach a low at term. HAND2 regulates a small but distinct set of target genes in endometrial stromal fibroblasts including the cytokine IL15, which was also dynamically expressed throughout the menstrual cycle and gestation, and promoted the migration of natural killer cells and extravillous cytotrophoblasts. Remarkably, we found that the HAND2 promoter loops to a distal enhancer containing SNPs implicated in the regulation of gestation length and birth weight. Collectively, these data connect HAND2 expression at the maternal-fetal interface with the evolution of implantation and gestation length regulation, and preterm birth.

A limitation of current methods for the generation of endometrial gland organoids is their reliance on decidua isolated from endometrial biopsies or elective abortion. Here we report the establishment of endometrial gland organoids from decidua isolated from term placental membranes. These organoids express typical markers of glandular epithelia such as E-cadherin, Laminin and Cytokeratin 7, and can be propagated in cell culture through multiple passages. Additionally, we identified potential survival factors for the co-culture of organoids and endometrial stromal fibroblasts. These modifications facilitate the generation of patient-specific endometrial gland organoids with known pregnancy outcomes.

The steroid hormone progesterone, acting through the progesterone receptor (PR), a ligand-activated DNA-binding transcription factor, plays an essential role in regulating nearly every aspect of female reproductive biology. While many reproductive traits regulated by PR are conserved in mammals, Catarrhine primates evolved several derived traits including spontaneous decidualization, menstruation, and a divergent (and unknown) parturition signal, suggesting that PR may also have evolved divergent functions in Catarrhines. There is conflicting evidence, however, whether the progesterone receptor gene (PGR) was positively selected in the human lineage. Here we show that PGR evolved rapidly in the human stem-lineage (as well as other Catarrhine primates), which likely reflects an episode of relaxed selection intensity rather than positive selection. Coincident with the episode of relaxed selection intensity, ancestral sequence resurrection and functional tests indicate that the major human PR isoforms (PR-A and PR-B) evolved divergent functions in the human stem-lineage. These results suggest that the regulation of progesterone signaling by PR-A and PR-B may also have diverged in the human lineage and that non-human animal models of progesterone signaling may not faithfully recapitulate human biology., Author summary The hormone progesterone regulates nearly every aspect of female reproductive biology, including when implantation will occur, the timing of the reproductive cycle, as well as the maintenance and cessation of pregnancy at term. These actions are mediated by the progesterone receptor, a transcription factor that binds progesterone and controls the expression of thousands of genes related to reproductive biology. Remarkably, previous studies have suggested that the progesterone receptor evolved rapidly in humans, with signatures of positive selection. However, using a large dataset of mammalian progesterone receptor genes, we found that selection on the progesterone receptor has actually been weakened in humans, with no evidence for positive selection. To explore if this human-specific episode of relaxed selection is associated with functional changes, we resurrected ancestral forms of the progesterone receptor and tested their ability to regulate a target gene. We found that the human progesterone receptor forms have changed in function, suggesting the actions regulated by progesterone may also be different in humans. Our results suggest caution in attempting to apply findings from animal models to progesterone biology of humans.

A major limitation of recently developed methods for the generation of endometrial gland organoids is their reliance on decidua isolated from endometrial biopsies or elective termination of pregnancies. Here we report the successful establishment of endometrial gland organoids from decidua isolated from term placental membranes, as well as the identification of potential survival factors for the co-culture of gland organoids and endometrial stromal fibroblasts. These modifications facilitate the generation of patient-specific endometrial gland organoids with known pregnancy outcomes, such as term vs. preterm birth.

SummaryFgf8 encodes a key signaling factor, and its precise regulation is essential for embryo patterning. Here, we identified the regulatory modules that control Fgf8 expression during mammalian embryogenesis. These enhancers are interspersed with unrelated genes along a large region of 220 kb; yet they act on Fgf8 only. Intriguingly, this region also contains additional genuine enhancer activities that are not transformed into gene expression. Using genomic engineering strategies, we showed that these multiple and distinct regulatory modules act as a coherent unit and influence genes depending on their position rather than on their promoter sequence. These findings highlight how the structure of a locus regulates the autonomous intrinsic activities of the regulatory elements it contains and contributes to their tissue and target specificities. We discuss the implications of such regulatory systems regarding the evolution of gene expression and the impact of human genomic structural variations.

Spectrophotometric titrations revealed that stability of the quercetin/double stranded (ds) DNA or double stranded (ds) RNA non-covalent complexes is significantly higher compared to the quercetin/ss-RNA complexes. This observation can easily be correlated with the significantly larger aromatic surface of base pairs compared to single nucleobases, and it is in good agreement with other experimental data pointing toward intercalative binding mode of quercetin. Fluorescence increase of quercetin induced by ds-RNA is significantly stronger than observed for ds-DNA, offering usage of quercetin as the ds-RNA selective fluorescent probe. Also, addition of poly G yielded more than order of magnitude stronger changes in UV/visible and fluorescence spectrum of quercetin compared to the changes upon addition of poly A and poly U revealing possible usage of quercetin as a powerful spectroscopic probe for poly G sequences. Stability and stoichiometry of lanthane(III)/quercetin complexes in physiologically relevant aqueous media was determined. The interactions of (LaQ)(3+) with double stranded DNA and RNA were significantly different compared to the free quercetin, revealing increase of complex stability and thus significant impact of La(III) in binding of (LaQ)(3+) to polynucleotides. Similar results were observed for interactions of (LaQ)(3+) with single stranded RNA.

The new bis-phenanthridine triamine (3) is characterised by three pKa values: 3.65; 6.0 and >7.5. A significant difference in the protonation state of 3 at pH = 5 (four positive charges) and at pH = 7 (less than two positive charges) accounts for the strong dependence of 3–nucleotide binding constants on nucleotide charge under acidic conditions, whereas at neutral pH all 3–nucleotide complexes are of comparable stability. All experimental data point at intercalation as the dominant binding mode of 3 to polynucleotides. However, there is no indication of bis-intercalation of the two phenanthridine subunits in binding to double stranded polynucleotides, the respective complexes being most likely mono-intercalative. Thermal stabilisation of calf thymus DNA (ct-DNA) and poly A–poly U duplexes upon addition of 3 is significantly higher at pH = 5 than at neutral conditions. This is not the case with poly dA–poly dT, indicating that the specific secondary structure of the latter, most likely the shape of the minor groove, plays a key role in complex stability. At pH = 5 3 acts as a fluorimetric probe for poly G (emission quenching) as opposed to other ss-polynucleotides (emission increase), while at neutral conditions this specificity is lost. One order of magnitude higher cytotoxicity of 3 compared to its “monomer” 4 can be accounted for by cooperative action of two phenanthridinium units and the charged triamine linker. The results presented here are of interest to the development of e.g. sequence-selective cytostatic drugs, and in particular for the possibility to control the drug activity properties over binding to DNA and/or RNA by variation of the pH of its surrounding.