Mechanism of hematopoiesis and vasculogenesis in mouse placenta

Mechanisms of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao (huang qi) and Angelica sinensis (Oliv.) Diels (dang gui) in Ameliorating Hypoxia and Angiogenesis to Delay Pulmonary Nodule Malignant Transformation

Screening for pulmonary nodules (PN) using low-dose CT has proven effective in reducing lung cancer (LC) mortality. However, current treatments relying on follow-up and surgical excision fail to fully address clinical needs. Pathological angiogenesis plays a pivotal role in supplying oxygen necessary for the progression of PN to LC. The interplay between hypoxia and angiogenesis establishes a vicious cycle, rendering anti-angiogenesis therapy alone insufficient to prevent PN to LC transformation. In traditional Chinese medicine (TCM), PN is referred to as "Feiji," which is mainly attributed to Qi and blood deficiency, correspondingly, the most commonly prescribed medicines are Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao (huang qi) (AR) and Angelica sinensis (Oliv.) Diels (dang gui) (ARS). Modern pharmacological studies have demonstrated that AR and ARS possess immune-enhancing, anti-tumor, anti-inflammatory, and anti-angiogenic properties. However, the precise mechanisms through which AR and ARS exert anti-angiogenic effects to delay PN progression to LC remain inadequately understood. This review explores the critical roles of hypoxia and angiogenesis in the transition from PN to LC. It emphasizes that, compared to therapies targeting angiogenic growth factors alone, AR, ARS, and their compound-based prescriptions offer additional benefits. These include ameliorating hypoxia by restoring blood composition, enhancing vascular structure, accelerating circulation, promoting vascular normalization, and blocking or inhibiting various pro-angiogenic expressions and receptor interactions. Collectively, these actions inhibit angiogenesis and delay the PN-to-LC transformation. Finally, this review summarizes recent advancements in related research, identifies existing limitations and gaps in knowledge, and proposes potential strategies and recommendations to address these challenges.

Maternal Vitamin D3 Supplementation in an Oxidized-Oil Diet Protects Fetus from Developmental Impairment and Ameliorates Oxidative Stress in Mouse Placenta and Fetus

BACKGROUND

Fried food has increased in popularity worldwide. However, deep frying can increase the production of peroxidative toxins in food, which might be harmful to fetal development. The antioxidative effect of vitamin D3 (VD3) has been reported previously.

OBJECTIVES

This study aimed to explore how maternal VD3 supplementation in an oxidized-oil diet during gestation affects fetal antioxidative ability and development.

METHODS

Pregnant mice were randomly assigned into 3 groups: Control group (diet with fresh soybean oil), OSO group [diet with oxidized soybean oil (OSO)], and OSOV group (diet with OSO and 10,000 IU/Kg VD3). Mice were fed with the corresponding diet during gestation. On day 16.5 of gestation, the placenta and fetus were harvested to analyze antioxidative status.

RESULTS

Maternal oxidized-oil diet during gestation significantly reduced placental vessel abundance, labyrinth zone area, and fetal body weight. However, dietary VD3 supplementation prevented these negative effects of oxidized-oil diet. Maternal intake of oxidized-oil diet increased serum concentrations of malondialdehyde, total-nitric oxide synthase, and inducible nitric oxide synthase, whereas VD3 supplementation showed a protection effect on it. Additionally, maternal VD3 supplementation increased the levels of antioxidative enzymes and the nuclear translocation of nuclear factor erythroid 2-related factor 2 (NRF2), thereby protecting placenta and fetus from apoptosis and oxidative stress caused by an oxidized-oil diet. The gene expression and protein levels of a fatty acid transporter solute carrier family 27 member 1 in the fetal liver were increased by maternal VD3 supplementation under oxidized-oil diet. Notably, NRF2 could be co-immunoprecipitated with the VD receptor in the placenta.

CONCLUSIONS

Maternal VD3 supplementation could protect fetus from oxidized-oil diet induced developmental impairment by alleviating oxidative stress in the placenta and fetus through the VD receptor/NRF2 pathway, at least partially. Thus, ensuring adequate levels of VD3 through supplementation is often critical during pregnancy.

A Single Trophoblast Layer Acts as the Gatekeeper at the Endothelial-Hematopoietic Crossroad in the Placenta

During embryonic development the placental vasculature acts as a major hematopoietic niche, where endothelial to hematopoietic transition ensures emergence of hematopoietic stem cells (HSCs). However, the molecular mechanisms that regulate the placental hematoendothelial niche are poorly understood. Using a parietal trophoblast giant cell (TGC)-specific knockout mouse model and single-cell RNA-sequencing, we show that the paracrine factors secreted by the TGCs are critical in the development of this niche. Disruptions in the TGC-specific paracrine signaling leads to the loss of HSC population and the concomitant expansion of a KDR+/DLL4+/PROM1+ hematoendothelial cell-population in the placenta. Combining single-cell transcriptomics and receptor-ligand pair analyses, we also define the parietal TGC-dependent paracrine signaling network and identify Integrin signaling as a fundamental regulator of this process. Our study elucidates novel mechanisms by which non-autonomous signaling from the primary parietal TGCs maintain the delicate placental hematopoietic-angiogenic balance and ensures embryonic and extraembryonic development.

Structural characterization of Russula griseocarnosa polysaccharide and its improvement on hematopoietic function

The hematopoietic function of a polysaccharide derived from Russula griseocarnosa was demonstrated in K562 cells, and subsequently purified through chromatography to obtain RGP1. RGP1 is a galactan composed of 1,6-α-D-Galp as the main chain, with partial substitutions. A -CH3 substitution was detected at O-3 of 1,6-α-D-Galp. The possible branches at O-2 of 1,6-α-D-Galp was α-L-Fucp. In mice with cyclophosphamide (CTX)-induced hematopoietic dysfunction, RGP1 alleviated bone marrow damage and multinucleated giant cell infiltration of the spleen, increased the number of long-term hematopoietic stem cells, and regulated the levels of myeloid cells in the peripheral blood. Furthermore, RGP1 promoted the differentiation of activated T cells and CD4+ T cells without affecting natural killer cells and B cells. Proteomic analysis, detection of cytokines, and western blotting revealed that RGP1 could alleviate hematopoietic dysfunction by promoting the activation of CD4+ T cells and the Janus kinase/ signal transducer and activator of transcription 3 pathway. The present study provides experimental evidence to support the application of RGP1 in CTX-induced hematopoietic dysfunction.

Longitudinal intravital imaging of mouse placenta

Studying placental functions is crucial for understanding pregnancy complications. However, imaging placenta is challenging due to its depth, volume, and motion distortions. In this study, we have developed an implantable placenta window in mice that enables high-resolution photoacoustic and fluorescence imaging of placental development throughout the pregnancy. The placenta window exhibits excellent transparency for light and sound. By combining the placenta window with ultrafast functional photoacoustic microscopy, we were able to investigate the placental development during the entire mouse pregnancy, providing unprecedented spatiotemporal details. Consequently, we examined the acute responses of the placenta to alcohol consumption and cardiac arrest, as well as chronic abnormalities in an inflammation model. We have also observed viral gene delivery at the single-cell level and chemical diffusion through the placenta by using fluorescence imaging. Our results demonstrate that intravital imaging through the placenta window can be a powerful tool for studying placenta functions and understanding the placental origins of adverse pregnancy outcomes.

Fluoride-related changes in the fetal cord blood proteome; a pilot study

Background

Fluoride exposure during pregnancy has been associated with various effects on offspring, including changes in behavior and IQ. To provide clues to possible mechanisms by which fluoride affects human fetal development, we completed proteomic analyses of cord blood serum collected from second-trimester pregnant women residing in Northern California with either high or low fluoride exposure, as identified by maternal serum fluoride concentrations.

Objective

To identify changes in cord blood proteins associated with maternal serum fluoride concentration in pregnant women living in Northern California.

Methods

The proteomes of 19 archived second-trimester cord blood samples representing highest and lowest serum fluoride concentrations from a cohort of 48 women living in Northern California, previously analyzed for serum, urine and amniotic fluoride concentrations, were characterized by mass spectrometry. Proteins highly correlated to maternal serum fluoride concentrations were identified, and further compared in a group of samples from women with the highest serum fluoride to the group with the lowest maternal serum fluoride concentrations.

Results

Nine cord blood proteins were significantly correlated with maternal serum fluoride concentrations. Six of these proteins, including apolipoprotein B-100, delta homolog 1, coagulation factor X, mimecan, plasma kallikrein, and vasorin, were significantly decreased in the cord blood from women with the highest serum fluoride levels.

Conclusion

Changes in the relative amounts of second trimester cord blood proteins included proteins associated with the development of the fetal hematopoetic system.

The Prl3d1-Cre mouse line selectively induces the expression of Cre recombinase in parietal trophoblast giant cells

The placenta plays a pivotal role in the maintenance of normal pregnancy, but how it forms, matures, and performs its function remains poorly understood. Here, we describe a novel mouse line (Prl3d1-iCre) that expresses iCre recombinase under the control of the endogenous prl3d1 promoter. Prl3d1 has been proposed as a marker for distinguishing trophoblast giant cells (TGCs) from other trophoblast cells in the placenta. The in vivo efficiency and specificity of the Cre line were analyzed by interbreeding Prl3d1-iCre mice with B6-G/R reporter mice. Through anatomical studies of the placenta and other tissues of Prl3d1-iCre/+; B6-G/R mouse mice, we found that the tdTomato signal was expressed in parietal trophoblast giant cells (P-TGCs). Thus, we report a mouse line with ectopic Cre expression in P-TGCs, which provides a valuable tool for studying human pathological pregnancies caused by implantation failure or abnormal trophoblast secretion due to aberrant gene regulation.

Cysteamine and N-Acetyl-cysteine Alleviate Placental Oxidative Stress and Barrier Function Damage Induced by Deoxynivalenol

Sows are highly sensitive to deoxynivalenol (DON) and susceptible to reproductive toxicity caused by oxidative stress, but the potential mechanisms and effective interventions remain unclear. Here, we investigated the role of two antioxidants (cysteamine and N-acetyl-cysteine) in regulating the reproductive performance, redox status, and placental barrier function of sows and their potential mechanisms under DON exposure. Maternal dietary supply of antioxidants from day 85 of gestation to parturition reduced the incidence of stillbirths and low-birth-weight piglets under DON exposure. Moreover, the alleviation of DON-induced reproductive toxicity by dietary antioxidants was associated with the alleviation of placental oxidative stress, the enhancement of the placental barrier, and the vascular function of sows. Furthermore, in vivo and in vitro vascularized placental barrier modeling further demonstrated that antioxidants could reverse both DON transport across the placenta and DON-induced increase of placental barrier permeability. The molecular mechanism of antioxidant resistance to DON toxicity may be related to the signal transducer and activator of the transcription-3-occludin/zonula occludens-1 signaling pathway. Collectively, these results demonstrate the potential of antioxidants to protect the mother from DON-induced reproductive toxicity by alleviating placental oxidative stress and enhancing the placental barrier.

Lectin-based carbohydrate profile of megakaryocytes in murine fetal liver during development

Hematopoiesis is the process by which blood cells are generated. During embryonic development, these cells migrate through different organs until they reach the bone marrow, their definitive place in adulthood. Around E10.5, the fetal liver starts budding from the gut, where first hematopoietic cells arrive and expand. Hematopoietic cell migration occurs through cytokine stimulation, receptor expression, and glycosylation patterns on the cell surface. In addition, carbohydrates can modulate different cell activation states. For this reason, we aimed to characterize and quantify fetal megakaryocytic cells in mouse fetal liver according to their glycan residues at different gestational ages through lectins. Mouse fetuses between E11.5 and E18.5 were formalin-fixed and, paraffin-embedded, for immunofluorescence analysis using confocal microscopy. The results showed that the following sugar residues were expressed in proliferating and differentiating megakaryocytes in the fetal liver at different gestational ages: α-mannose, α-glucose, galactose, GlcNAc, and two types of complex oligosaccharides. Megakaryocytes also showed three proliferation waves during liver development at E12.5, E14.5, and E18.5. Additionally, the lectins that exhibited high and specific pattern intensities at liver capsules and vessels were shown to be a less time-consuming and robust alternative alternative to conventional antibodies for displaying liver structures such as capsules and vessels, as well as for megakaryocyte differentiation in the fetal liver.

Linking Benzene, in Utero Carcinogenicity and Fetal Hematopoietic Stem Cell Niches: A Mechanistic Review

Previous research reported that prolonged benzene exposure during in utero fetal development causes greater fetal abnormalities than in adult-stage exposure. This phenomenon increases the risk for disease development at the fetal stage, particularly carcinogenesis, which is mainly associated with hematological malignancies. Benzene has been reported to potentially act via multiple modes of action that target the hematopoietic stem cell (HSCs) niche, a complex microenvironment in which HSCs and multilineage hematopoietic stem and progenitor cells (HSPCs) reside. Oxidative stress, chromosomal aberration and epigenetic modification are among the known mechanisms mediating benzene-induced genetic and epigenetic modification in fetal stem cells leading to in utero carcinogenesis. Hence, it is crucial to monitor exposure to carcinogenic benzene via environmental, occupational or lifestyle factors among pregnant women. Benzene is a well-known cause of adult leukemia. However, proof of benzene involvement with childhood leukemia remains scarce despite previously reported research linking incidences of hematological disorders and maternal benzene exposure. Furthermore, accumulating evidence has shown that maternal benzene exposure is able to alter the developmental and functional properties of HSPCs, leading to hematological disorders in fetus and children. Since HSPCs are parental blood cells that regulate hematopoiesis during the fetal and adult stages, benzene exposure that targets HSPCs may induce damage to the population and trigger the development of hematological diseases. Therefore, the mechanism of in utero carcinogenicity by benzene in targeting fetal HSPCs is the primary focus of this review.

Effects of swimming before and during pregnancy on placental angiogenesis and perinatal outcome in high-fat diet-fed mice

Background

We explored the mechanism underlying exercise-mediated placental angiogenesis and perinatal outcome using mouse models.

Methods

Three-week-old C57BL/6 female mice were randomly divided into four experimental groups: standard-chow diet (SC), standard chow diet + exercise (SC-Ex), high-fat diet (HFD), and high-fat diet + exercise (HFD-Ex). After 13 weeks of exercise intervention, the male and female mice were caged. Approximately six to seven pregnant female mice from each experimental group were randomly selected for body composition, qRT-PCR, histological, and western blot analysis. The remaining mice were allowed to deliver naturally, and the perinatal outcome indexes were observed.

Rusults

The results showed that exercise intervention significantly improved the body composition and glucose tolerance in HFD-fed pregnant mice. The HFD group showed adipocyte infiltration, placental local hypoxia, and villous vascular thrombosis with a significant (p < 0.05) increase in the expression of VEGF and ANGPT1 proteins. Exercise intervention significantly elevated the expression of PPARγ, alleviated hypoxia and inflammation-related conditions, and inhibited angiogenesis. sFlt-1 mRNA in HFD group was significantly higher than that in SC group (p < 0.05). Furthermore, the HFD significantly reduced (p < 0.05) the fertility rate in mice.

Conclusions

Thus, HFD aggravates placental inflammation and the hypoxic environment and downregulates the expression of PPARγ and PPARα in the placenta. However, exercise intervention can significantly alleviate these conditions.

The vertical transmission of Salmonella Enteritidis in a One-Health context

Salmonella enterica serovar Enteritidis (S. Enteritidis, SE) is a foodborne zoonotic pathogen, causing economic losses in animal husbandry and large numbers of human deaths and critically threatening economic development and public health. Human infection with SE has complex transmission routes, involving the environment, animal reservoirs, and water in a One-Health context. Food-producing animals, particularly poultry and livestock, are regarded as the most common sources of SE infection in humans. However, there is little known about the vertical transmission of SE in a One-Health context. In this review, we analyze the ecological significance of SE in a One-Health context. Importantly, we focus on the difference in vertical transmission of SE in poultry, livestock, and humans. We introduce the transmission pathway, describe the immune mechanisms, and discuss the models that could be used for studying the vertical transmission of SE and the strategy that prevention and control for vertical transmission of SE into the future from a One-Health perspective. Together, considering the vertical transmission of SE, it is helpful to provide important insights into the control and decontamination pathways of SE in animal husbandry and enhance knowledge about the prevention of fetal infection in human pregnancy.

A study on the placenta in stillbirth: an evaluation of molecular alterations through next generation sequencing

INTRODUCTION

Placental dysfunction is one of the most common causes of Intrauterine Fetal Demise (IUFD). Due to its characteristics, the placenta may be the target of molecular research aimed to investigate potential causes of IUFD. In the literature, there are no studies on human placentas that have investigated possible associations between somatic mutations and the occurrence of IUFD. The aim of this study was to identify the presence of gene mutations in placental tissues in a series of cases of IUFD and to evaluate potential correlations with placental microscopic findings.

MATERIALS AND METHODS

Thirty-seven samples of formalin-fixed and paraffin-embedded placental tissues were retrospectively selected from pregnancies ending in IUFD between 23rd to 40th week. Six control placentas of physiological pregnancies were included as controls. After sampling, made according to standardized protocol and conventional histopathological examination, placental tissues were subjected to DNA extraction and sequencing by means of Next Generation Sequencing with a 56-gene panel.

RESULTS

The most frequent mutation observed in 32/37 IUFD cases (86.5%) and absent in any of the 6 control placentas was in c-KIT gene, which is implicated in placental tissue differentiation. However, no significant correlation was found between the presence of individual gene mutations and placental histopatological findings.

DISCUSSION

As the present study found an elevated frequency of c-KIT mutation in IUFD, it further supports the hypothesis that c-KIT is involved in abnormal tissue differentiation leading to altered placental vascularization and function.

Altered expression of Notch signaling, Tlr receptors, and surfactant protein expression after prostaglandin inhibition may be associated with the delayed labor in LPS-induced mice

PURPOSE

This study aims to investigate whether indomethacin (IND) delays preterm birth by regulating the Notch pathway, Tlr receptors, and Sp-A in the placenta in lipopolysaccharide (LPS)-induced preterm labor (PTL) model.

METHODS

CD-1 mice were distributed to the pregnant control (PC), Sham, PBS, IND (2 mg/kg; i.p.), LPS (25 μg/100 μl; intrauterine), and LPS + IND groups. The injections were performed on day 14.5 of pregnancy. Placentae were collected on day 15.5 of pregnancy, and immunohistochemical analyzes were performed. Differences in staining intensities between the Cox-1, Notch-1 (N1), Dll-1, Jagged-2 (Jag-2), Tlr-2, and Tlr-4 proteins were compared.

RESULTS

Preterm labor rates were 100% and 66% (preterm delivery delayed 5 h) in the LPS and LPS + IND groups, respectively. In LPS-treated mice, a general morphological deterioration was observed in the placenta. Total placental mid-sagittal measurement was significantly reduced in the LPS-treated group, while it was similar to the PC group in the LPS + IND group. Cox-1 expression in the LZ increased, and Sp-A expression decreased after LPS injection, and IND administration diminished this increase. N1 expression increased in the labyrinth zone (LZ) and the junctional zone (JZ). Dll-1 and Jag-2 expression increased in the JZ after LPS injection (p < 0.0001). IND administration diminished Tlr-2 expression in the LZ and Tlr-4 expression in the JZ after LPS injection.

CONCLUSION

In conclusion, PG (prostaglandin) inhibition may alter Notch signaling, Tlr, and Sp-A protein expression and may be associated with delayed labor in LPS-induced mice.

Glucose-6-Phosphate Dehydrogenase, Redox Homeostasis and Embryogenesis

Normal embryogenesis requires complex regulation and precision, which depends on multiple mechanistic details. Defective embryogenesis can occur by various mechanisms. Maintaining redox homeostasis is of importance during embryogenesis. NADPH, as produced from the action of glucose-6-phosphate dehydrogenase (G6PD), has an important role in redox homeostasis, serving as a cofactor for glutathione reductase in the recycling of glutathione from oxidized glutathione and for NADPH oxidases and nitric oxide synthases in the generation of reactive oxygen (ROS) and nitrogen species (RNS). Oxidative stress differentially influences cell fate and embryogenesis. While low levels of stress (eustress) by ROS and RNS promote cell growth and differentiation, supra-physiological concentrations of ROS and RNS can lead to cell demise and embryonic lethality. G6PD-deficient cells and organisms have been used as models in embryogenesis for determining the role of redox signaling in regulating cell proliferation, differentiation and migration. Embryogenesis is also modulated by anti-oxidant enzymes, transcription factors, microRNAs, growth factors and signaling pathways, which are dependent on redox regulation. Crosstalk among transcription factors, microRNAs and redox signaling is essential for embryogenesis.

Development of the Mouse Placenta

Placenta forms as a momentary organ inside the uterus with a slew of activities only when the woman is pregnant. It is a discoid-shaped hybrid structure consisting of maternal and embryonic components. It develops in the mesometrial side of the uterus following blastocyst implantation to keep the two genetically different entities, the mother and embryo, separated but connected. The beginning and progression of placental formation and development following blastocyst implantation coincides with the chronological developmental stages of the embryo. It gradually acquires the ability to perform the vascular, respiratory, hepatic, renal, endocrine, gastrointestinal, immune, and physical barrier functions synchronously that are vital for fetal development, growth, and safety inside the maternal environment. The uterus ejects the placenta when its embryonic growth and survival supportive roles are finished; that is usually the birth of the baby. Despite its irreplaceable role in fetal development and survival over the post-implantation progression of pregnancy, it still remains unclear how it forms, matures, performs all of its activities, and starts to fail functioning. Thus, a detailed understanding about normal developmental, structural, and functional aspects of the placenta may lead to avoid pregnancy problems that arise with the placenta.

Diverse cellular origins of adult blood vascular endothelial cells

During embryonic stages, vascular endothelial cells (ECs) originate from the mesoderm, at specific extraembryonic and embryonic regions, through a process called vasculogenesis. In the adult, EC renewal/replacement mostly depend on local resident ECs or endothelial progenitor cells (EPCs). Nevertheless, contribution from circulating ECs/EPCs was also reported. In addition, cells lacking from EC/EPC markers with in vitro extended plasticity were shown to originate endothelial-like cells (ELCs). Most of these cells consist of mesenchymal stromal progenitors, which would eventually get mobilized from the bone marrow after injury. Based on that, current knowledge on different mouse and human bone marrow stromal cell (BM-SC) subpopulations, able to contribute with mesenchymal stromal/stem cells (MSCs), is herein reviewed. Such analyses underline an unexpected heterogeneity among sinusoidal LepR⁺ stromal/CAR cells. For instance, in a recent report a subgroup of LepR⁺ stromal/CAR progenitors, which express GLAST and is traced in Wnt1^Cre;R26R^Tom mice, was found to contribute with ELCs in vivo. These GLAST ​⁺ ​Wnt1⁺ BM-SCs were shown to get mobilized to the peripheral blood and to contribute with liver regeneration. Other sources of ELCs, such as adipose, neural and dental pulp tissues, were also published. Finally, mechanisms likely involved in the enhanced cellular plasticity properties of bone marrow/adipose tissue stromal cells, able to originate ELCs, are assessed. In the future, strategies to analyze the in vivo expression profile of stromal cells, with MSC properties, in combination with screening of active genomic regions at the single cell-level, during early postnatal development and/or after injury, will likely help understanding properties of these ELC sources.

Placental hypoxia: What have we learnt from small animal models?

Intrauterine hypoxia is a feature of pregnancy complications, both at high altitude and sea level. To understand the placental response to reduced oxygen availability, small animal models of maternal inhalation hypoxia (MIH) or reduced uterine perfusion pressure (RUPP) may be utilised. The aim of this review was to compare the findings of those studies to identify the role of oxygen availability in adapting placental structural and functional phenotypes in relation to fetal outcome. It also sought to explore the evidence for the involvement of particular genes and protein signalling pathways in the placenta in mediating hypoxia driven alterations. The data available demonstrate that both MIH and RUPP can induce placental hypoxia, which affects placental structure and vascularity, as well as glucose, amino acid, calcium and possibly lipid transport capacity. In addition, changes have been observed in HIF, VEGF, insulin/IGF2, AMPK, mTOR, PI3K and PPARγ signalling, which may be key in linking together observed phenotypes under conditions of placental hypoxia. Many different manipulations have been examined, with varied outcomes depending on the intensity, timing and duration of the insult. Some manipulations have detrimental effects on placental phenotype, viability and fetal growth, whereas in others, the placenta appears to adapt to uphold fetal growth despite the challenge of low oxygen. Together these data suggest a complex response of the placenta to reduced oxygen availability, which links to changes in fetal outcomes. However, further work is required to explore the role of fetal sex, altered maternal physiology and placental molecular mechanisms to fully understand placental responses to hypoxia and their relevance for pregnancy outcome.

The Hippo pathway component Wwc2 is a key regulator of embryonic development and angiogenesis in mice

The WW-and-C2-domain-containing (WWC) protein family is involved in the regulation of cell differentiation, cell proliferation, and organ growth control. As upstream components of the Hippo signaling pathway, WWC proteins activate the Large tumor suppressor (LATS) kinase that in turn phosphorylates Yes-associated protein (YAP) and its paralog Transcriptional coactivator-with-PDZ-binding motif (TAZ) preventing their nuclear import and transcriptional activity. Inhibition of WWC expression leads to downregulation of the Hippo pathway, increased expression of YAP/TAZ target genes and enhanced organ growth. In mice, a ubiquitous Wwc1 knockout (KO) induces a mild neurological phenotype with no impact on embryogenesis or organ growth. In contrast, we could show here that ubiquitous deletion of Wwc2 in mice leads to early embryonic lethality. Wwc2 KO embryos display growth retardation, a disturbed placenta development, impaired vascularization, and finally embryonic death. A whole-transcriptome analysis of embryos lacking Wwc2 revealed a massive deregulation of gene expression with impact on cell fate determination, cell metabolism, and angiogenesis. Consequently, a perinatal, endothelial-specific Wwc2 KO in mice led to disturbed vessel formation and vascular hypersprouting in the retina. In summary, our data elucidate a novel role for Wwc2 as a key regulator in early embryonic development and sprouting angiogenesis in mice.

Abnormal angiogenesis of placenta in progranulin‑deficient mice

Progranulin (PGRN) is a secreted growth factor involved in pleiotropic functions, particularly angiogenesis. A distinctly different placental expression of PGRN has been reported between normal pregnancies and pregnancies with complications, such as pre‑eclampsia or fetal growth restriction. However, the role of PGRN in placental vascular development remains to be elucidated. In the present study, PGRN‑knockout mice (PGRN‑/‑) were used to investigate the role of PGRN in the development of placental blood vessels and placental formation. Placental weights and pup body weights were significantly lower in the PGRN‑/‑ mice compared with the wild‑type mice. Reduced labyrinthine layer areas and aberrant vascularization were also observed via hematoxylin and eosin staining of PGRN‑/‑ mice at embryonic day 14.5 (E14.5) and E17.5. In addition, the morphological data obtained via immunohistochemistry, immunofluorescence staining and western blotting demonstrated decreased expression levels of the blood vessel markers α‑smooth muscle actin and CD31 in PGRN‑/‑ placentas. Furthermore, vasodilator endothelial nitric oxide synthase was reduced in the PGRN‑/‑ placenta. These results indicated that PGRN serves an essential role in the normal angiogenesis of the placental labyrinth in mice.

Persistent Human KIT Receptor Signaling Disposes Murine Placenta to Premature Differentiation Resulting in Severely Disrupted Placental Structure and Functionality

Activating mutations in the human KIT receptor is known to drive severe hematopoietic disorders and tumor formation spanning various entities. The most common mutation is the substitution of aspartic acid at position 816 to valine (D816V), rendering the receptor constitutively active independent of ligand binding. As the role of the KIT receptor in placental signaling cascades is poorly understood, we analyzed the impact of KIT^D816V expression on placental development using a humanized mouse model. Placentas from KIT^D816V animals present with a grossly changed morphology, displaying a reduction in labyrinth and spongiotrophoblast layer and an increase in the Parietal Trophoblast Giant Cell (P-TGC) layer. Elevated differentiation to P-TGCs was accompanied with reduced differentiation to other Trophoblast Giant Cell (TGC) subtypes and by severe decrease in proliferation. The embryos display growth retardation and die in utero. KIT^D816V-trophoblast stem cells (TSC) differentiate much faster compared to wild type (WT) controls. In undifferentiated KIT^D816V-TSCs, levels of Phosphorylated Extracellular-signal Regulated Kinase (P-ERK) and Phosphorylated Protein Kinase B (P-AKT) are comparable to wildtype cultures differentiating for 3–6 days. Accordingly, P-TGC markers Placental Lactogen 1 (PL1) and Proliferin (PLF) are upregulated as well. The results reveal that KIT signaling orchestrates the fine-tuned differentiation of the placenta, with special emphasis on P-TGC differentiation. Appropriate control of KIT receptor action is therefore essential for placental development and nourishment of the embryo.