Single-cell multi-omic analysis profiles defective genome activation and epigenetic reprogramming associated with human pre-implantation embryo arrest.

During pre-implantation stages of mammalian development, maternally stored material promotes both the erasure of the sperm and oocyte epigenetic profiles and is responsible for concomitant genome activation. Here, we have utilized single-cell methylome and transcriptome sequencing (scM&T-seq) to quantify both mRNA expression and DNA methylation in oocytes and a developmental series of human embryos at single-cell resolution. We fully characterize embryonic genome activation and maternal transcript degradation and map key epigenetic reprogramming events in developmentally high-quality embryos.

Mechanisms and function of de novo DNA methylation in placental development reveals an essential role for DNMT3B.

DNA methylation is a repressive epigenetic modification that is essential for development, exemplified by the embryonic and perinatal lethality observed in mice lacking de novo DNA methyltransferases (DNMTs). Here we characterise the role for DNMT3A, 3B and 3L in gene regulation and development of the mouse placenta. We find that each DNMT establishes unique aspects of the placental methylome through targeting to distinct chromatin features.

Multi-omics analyses demonstrate a critical role for EHMT1 methyltransferase in transcriptional repression during oogenesis.

EHMT1 (also known as GLP) is a multifunctional protein, best known for its role as an H3K9me1 and H3K9me2 methyltransferase through its reportedly obligatory dimerization with EHMT2 (also known as G9A). Here, we investigated the role of EHMT1 in the oocyte in comparison to EHMT2 using oocyte-specific conditional knockout mouse models ( cKO, cKO, cDKO), with ablation from the early phase of oocyte growth. Loss of EHMT1 in cKO and cDKO oocytes recapitulated meiotic defects observed in the cKO; however, there was a significant impairment in oocyte maturation and developmental competence in cKO and cDKO oocytes beyond that observed in the cKO.

Perturbation of placental protein glycosylation by endoplasmic reticulum stress promotes maladaptation of maternal hepatic glucose metabolism.

Placental hormones orchestrate maternal metabolic adaptations to support pregnancy. We hypothesized that placental ER stress, which characterizes early-onset pre-eclampsia (ePE), compromises glycosylation, reducing hormone bioactivity and these maladaptations predispose the mother to metabolic disease in later life. We demonstrate ER stress reduces the complexity and sialylation of trophoblast protein N-glycosylation, while aberrant glycosylation of vascular endothelial growth factor reduced its bioactivity.

Epigenetic resetting in the human germ line entails histone modification remodeling.

Epigenetic resetting in the mammalian germ line entails acute DNA demethylation, which lays the foundation for gametogenesis, totipotency, and embryonic development. We characterize the epigenome of hypomethylated human primordial germ cells (hPGCs) to reveal mechanisms preventing the widespread derepression of genes and transposable elements (TEs). Along with the loss of DNA methylation, we show that hPGCs exhibit a profound reduction of repressive histone modifications resulting in diminished heterochromatic signatures at most genes and TEs and the acquisition of a neutral or paused epigenetic state without transcriptional activation.

Genome-wide assessment of DNA methylation alterations induced by superovulation, sexual immaturity and in vitro follicle growth in mouse blastocysts.

Background: In their attempt to fulfill the wish of having children, women who suffer from fertility issues often undergo assisted reproductive technologies such as ovarian stimulation, which has been associated with adverse health outcomes and imprinting disorders in children. However, given the crucial role of exogenous hormone stimulation in improving human infertility treatments, a more comprehensive analysis of the potential impacts on DNA methylation in embryos following ovarian stimulation is needed. Here, we provide genome-wide DNA methylation profiles of blastocysts generated after superovulation of prepubertal or adult mice, compared with blastocysts derived from non-stimulated adult mice.

NANOGP1, a tandem duplicate of NANOG, exhibits partial functional conservation in human naïve pluripotent stem cells.

Gene duplication events can drive evolution by providing genetic material for new gene functions, and they create opportunities for diverse developmental strategies to emerge between species. To study the contribution of duplicated genes to human early development, we examined the evolution and function of NANOGP1, a tandem duplicate of the transcription factor NANOG. We found that NANOGP1 and NANOG have overlapping but distinct expression profiles, with high NANOGP1 expression restricted to early epiblast cells and naïve-state pluripotent stem cells.

Placental F-Neuroprostanes and F-Isoprostanes are altered in gestational diabetes mellitus and maternal obesity.

We investigated whether gestational diabetes mellitus (GDM) associated with maternal obesity modifies the placental profile of F-Neuroprostanes and F-Isoprostanes, metabolites of non-enzymatic oxidation of docosahexaenoic acid (DHA) and arachidonic acid (AA), respectively. Twenty-five placental samples were divided into lean (n=11), obesity (n=7) and overweight/obesity+GDM (n=7) groups. F-Neuroprostanes and F-Isoprostanes were higher in obesity compared to lean controls, but reduced to levels similar to lean women when obesity is further complicated with GDM.

Sex-Specific Differences in the Placental Unfolded Protein Response in a Rodent Model of Gestational Hypoxia.

Gestational hypoxia is a major contributor to fetal growth restriction (FGR) and perinatal morbidity and mortality and has been closely linked to the activation of the unfolded protein response (UPR) in the placenta. Recent studies on adverse pregnancy conditions show differential adaptive responses in pregnancies carrying male or female fetuses. Here, we use an established rat model of hypoxic pregnancy and FGR to test the hypothesis that chronic hypoxia promotes sexually dimorphic activation of the placental UPR.

Effect of Superovulation Treatment on Oocyte's DNA Methylation.

Controlled ovarian stimulation is a necessary step in some assisted reproductive procedures allowing a higher collection of female gametes. However, consequences of this stimulation for the gamete or the offspring have been shown in several mammals. Most studies used comparisons between oocytes from different donors, which may contribute to different responses.

Sphingolipids and acylcarnitines are altered in placentas from women with gestational diabetes mellitus.

Gestational diabetes mellitus (GDM) is the most common medical complication of pregnancy and a severe threat to pregnant people and offspring health. The molecular origins of GDM, and in particular the placental responses, are not fully known. The present study aimed to perform a comprehensive characterisation of the lipid species in placentas from pregnancies complicated with GDM using high-resolution MS lipidomics, with a particular focus on sphingolipids and acylcarnitines in a semi-targeted approach.

Requirement for STAT3 and its target, TFCP2L1, in self-renewal of naïve pluripotent stem cells in vivo and in vitro.

We previously demonstrated gradual loss of epiblast during diapause in embryos lacking components of the LIF/IL6 receptor. Here, we explore the requirement for the downstream signalling transducer andactivator of transcription STAT3 and its target, TFCP2L1, in maintenance of naïve pluripotency. Unlike conventional markers, such as NANOG, which remains high in epiblast until implantation, both STAT3 and TFCP2L1 proteins decline during blastocyst expansion, but intensify in the embryonic region after induction of diapause, as observed visually and confirmed using our image-analysis pipeline, consistent with our previous transcriptional expression data.

Placental adaptations supporting fetal growth during normal and adverse gestational environments.

New Findings: What is the topic of this review? How the placenta, which transports nutrients and oxygen to the fetus, may alter its support of fetal growth developmentally and with adverse gestational conditions. What advances does it highlight? Placental formation and function alter with the needs of the fetus for substrates for growth during normal gestation and when there is enhanced competition for substrates in species with multiple gestations or adverse gestational environments, and this is mediated by imprinted genes, signalling pathways, mitochondria and fetal sexomes.

Abstract: The placenta is vital for mammalian development and a key determinant of life-long health.

Why mothers die at a busy tertiary urban hospital in Kampala, Uganda: a comprehensive review of maternal deaths 2016-2018 and implications for quality improvement to reduce deaths.

Background: Reviewing maternal deaths and drawing out lessons for clinical practice is part of an effective cohesive intervention strategy to reduce future deaths.

Objective: To review maternal deaths at the National Referral hospital in Kampala over a 3-year period (2016-2018) to determine causes of death, extent of preventability, proportion of deaths notified and audited as per national guidelines.

Methods: Trained-multidisciplinary panels (obstetricians and senior midwives) conducted retrospective reviews of maternal deaths that occurred.

Variable allelic expression of imprinted genes at the , , cluster in single neural cells.

Genomic imprinting is an epigenetic process through which genes are expressed in a parent-of-origin specific manner resulting in mono-allelic or strongly biased expression of one allele. For some genes, imprinted expression may be tissue-specific and reliant on CTCF-influenced enhancer-promoter interactions. The imprinting cluster is associated with neurodevelopmental disorders and comprises canonical imprinted genes, which are conserved between mouse and human, as well as brain-specific imprinted genes in mouse.

Learning from maternal deaths due to uterine rupture: review of cases from peri-urban Uganda.

Background: Maternal deaths from uterine rupture continue to occur globally, with particularly high rates in sub-Saharan Africa. Maternal death reviews have been shown to be an effective part of cohesive strategies to prevent future deaths.

Objective: This study aimed to conduct maternal death reviews for all deaths following uterine rupture in the study center, to assess preventability, and to synthesize key learning points that may help to prevent future maternal deaths following uterine rupture.

Evolutionary divergence of embryo implantation in primates.

Implantation of the conceptus into the uterus is absolutely essential for successful embryo development. In humans, our understanding of this process has remained rudimentary owing to the inaccessibility of early implantation stages. Non-human primates recapitulate many aspects of human embryo development and provide crucial insights into trophoblast development, uterine receptivity and embryo invasion.

The effect of antenatal corticosteroid use on offspring cardiovascular function: A systematic review.

Background: Antenatal corticosteroids (ACS) are recommended in threatened preterm labour to improve short-term neonatal outcome. Preclinical animal studies suggest detrimental effects of ACS exposure on offspring cardiac development; their effects in humans are unknown.

Objectives: To systematically review the human clinical literature to determine the effects of ACS on offspring cardiovascular function.

Uterine NK Cells Ace an "A" in Education: NKG2A Sets Up Crucial Functions at the Maternal-Fetal Interface.

I argue in this review that reproduction was a driving force in the evolution of NK cell education, which is set by interactions between inhibitory receptors and self-MHC. Maternal lymphocytes also interact with allogeneic MHC on fetal trophoblast cells. How the maternal immune system tolerate the semiallogeneic fetus is a fascinating question.

Single-cell multi-omics profiling links dynamic DNA methylation to cell fate decisions during mouse early organogenesis.

Background: Perturbation of DNA methyltransferases (DNMTs) and of the active DNA demethylation pathway via ten-eleven translocation (TET) methylcytosine dioxygenases results in severe developmental defects and embryonic lethality. Dynamic control of DNA methylation is therefore vital for embryogenesis, yet the underlying mechanisms remain poorly understood.

Results: Here we report a single-cell transcriptomic atlas from Dnmt and Tet mutant mouse embryos during early organogenesis.

Protocol to isolate and culture primary mouse feto-placental endothelial cells.

In the mouse, feto-placental endothelial cells (FPEC) line the inner surface of the feto-placental blood vessels located within placental labyrinthine zone and play critical roles in placental development and function. Here, we present a detailed protocol for isolation and culture of primary mouse FPEC, as well as two complementary methods (immunohistochemistry staining and flow cytometry analysis) to assess their purity. These cells are suitable for downstream ex vivo studies to investigate their functional properties, both in normal and pathological contexts.

Maternal and Fetal PI3K-p110α Deficiency Induces Sex-Specific Changes in Conceptus Growth and Placental Mitochondrial Bioenergetic Reserve in Mice.

Fetal growth is reliant on placental formation and function, which, in turn, requires the energy produced by the mitochondria. Prior work has shown that both mother and fetus operate via the phosphoinositol 3-kinase (PI3K)-p110α signalling pathway to modify placental development, function, and fetal growth outcomes. This study in mice used genetic inactivation of PI3K-p110α (α/+) in mothers and fetuses and high resolution respirometry to investigate the influence of maternal and fetal PI3K-p110α deficiency on fetal and placental growth, in relation to placental mitochondrial bioenergetics, for each fetal sex.