miR-126 regulates glycogen trophoblast proliferation and DNA methylation in the murine placenta

Maternal RNA transcription in Dlk1-Dio3 domain is critical for proper development of the mouse placental vasculature

The placenta is a unique organ for ensuring normal embryonic growth in the uterine. Here, we found that maternal RNA transcription in Dlk1-Dio3 imprinted domain is essential for placentation. PolyA signals were inserted into Gtl2 to establish a mouse model to prevent the expression of maternal RNAs in the domain. The maternal allele knock-in (MKI) and homozygous (HOMO) placentas showed an expanded junctional zone, reduced labyrinth and poor vasculature impacting both fetal and maternal blood spaces. The MKI and HOMO models displayed dysregulated gene expression in the Dlk1-Dio3 domain. In situ hybridization detected Dlk1, Gtl2, Rtl1, miR-127 and Rian dysregulated in the labyrinth vasculature. MKI and HOMO induced Dlk1 to lose imprinting, and DNA methylation changes of IG-DMR and Gtl2-DMR, leading to abnormal gene expression, while the above changes didn't occur in paternal allele knock-in placentas. These findings demonstrate that maternal RNAs in the Dlk1-Dio3 domain are involved in placental vasculature, regulating gene expression, imprinting status and DNA methylation.

Exploring the role of miRNAs in early chicken embryonic development and their significance

In the early stages of embryonic development, a precise and strictly controlled hierarchy of gene expression is essential to ensure proper development of all cell types and organs. To better understand this gene control process, we constructed a small RNA library from 1- to 5-day-old chick embryos, and identified 2,459 miRNAs including 827 existing, 695 known, and 937 novel miRNAs with bioinformatic analysis. There was absolute high expression of a number of miRNAs in each stage, including gga-miR-363-3p (Em1d), gga-miR-26a-5p (Em2d and Em3d), gga-miR-10a-5p (Em4d), and gga-miR-199-5p (Em5d). We evaluated enriched miRNA profiles, identifying VEGF, Insulin, ErbB, MAPK, Hedgehog, TLR and Hippo signaling pathways as primary regulatory mechanisms enabling complex morphogenetic transformations within tight temporal constraints. Pathway analysis revealed miRNAs as pivotal nodes of interaction, coordinating cascades of gene expression critical for cell fate determination, proliferation, migration, and differentiation across germ layers and developing organ systems. Weighted Gene Co-Expression Network Analysis (WGCNA) generated hub miRNAs whose modular connections spanned regulatory networks, including: gga-miR-181a-3p (blue module), coordinating immunegenesis and myogenesis; gga-miR-126-3p (brown module), regulating vasculogenesis and angiogenesis; gga-miR-302c-5p (turquoise module), enabling pluripotency and self-renew; and gga-miR-429-3p (yellow module), modulating neurogenesis and osteogenesis. The findings of this study extend the knowledge of miRNA expression in early embryonic development of chickens, providing insights into the intricate gene control process that helps ensure proper development.

Trophoblast Differentiation: Mechanisms and Implications for Pregnancy Complications

Placental development is a tightly controlled event, in which cell expansion from the trophectoderm occurs in a spatiotemporal manner. Proper trophoblast differentiation is crucial to the vitality of this gestational organ. Obstructions to its development can lead to pregnancy complications, such as preeclampsia, fetal growth restriction, and preterm birth, posing severe health risks to both the mother and offspring. Currently, the only known treatment strategy for these complications is delivery, making it an important area of research. The aim of this review was to summarize the known information on the development and mechanistic regulation of trophoblast differentiation and highlight the similarities in these processes between the human and mouse placenta. Additionally, the known biomarkers for each cell type were compiled to aid in the analysis of sequencing technologies.

Roles of physical exercise-induced MiR-126 in cardiovascular health of type 2 diabetes

Although physical activity is widely recommended for preventing and treating cardiovascular complications of type 2 diabetes mellitus (T2DM), the underlying mechanisms remain unknown. MicroRNA-126 (miR-126) is an angiogenetic regulator abundant in endothelial cells (ECs) and endothelial progenitor cells (EPCs). It is primarily involved in angiogenesis, inflammation and apoptosis for cardiovascular protection. According to recent studies, the levels of miR-126 in the myocardium and circulation are affected by exercise protocol. High-intensity interval training (HIIT) or moderate-and high-intensity aerobic exercise, whether acute or chronic, can increase circulating miR-126 in healthy adults. Chronic aerobic exercise can effectively rescue the reduction of myocardial and circulating miR-126 and vascular endothelial growth factor (VEGF) in diabetic mice against diabetic vascular injury. Resistance exercise can raise circulating VEGF levels, but it may have a little influence on circulating miR-126. The Several targets of miR-126 have been suggested for cardiovascular fitness, such as sprouty-related EVH1 domain-containing protein 1 (SPRED1), phosphoinositide-3-kinase regulatory subunit 2 (PIK3R2), vascular cell adhesion molecule 1 (VCAM1), high-mobility group box 1 (HMGB1), and tumor necrosis factor receptor-associated factor 7 (TRAF7). Here, we present a comprehensive review of the roles of miR-126 and its downstream proteins as exercise mechanisms, and propose that miR-126 can be applied as an exercise indicator for cardiovascular prescriptions and as a preventive or therapeutic target for cardiovascular complications in T2DM.

Loss of imprinting of the Igf2-H19 ICR1 enhances placental endocrine capacity via sex-specific alterations in signalling pathways in the mouse

Imprinting control region (ICR1) controls the expression of the Igf2 and H19 genes in a parent-of-origin specific manner. Appropriate expression of the Igf2-H19 locus is fundamental for normal fetal development, yet the importance of ICR1 in the placental production of hormones that promote maternal nutrient allocation to the fetus is unknown. To address this, we used a novel mouse model to selectively delete ICR1 in the endocrine junctional zone (Jz) of the mouse placenta (Jz-ΔICR1). The Jz-ΔICR1 mice exhibit increased Igf2 and decreased H19 expression specifically in the Jz. This was accompanied by an expansion of Jz endocrine cell types due to enhanced rates of proliferation and increased expression of pregnancy-specific glycoprotein 23 in the placenta of both fetal sexes. However, changes in the endocrine phenotype of the placenta were related to sexually-dimorphic alterations to the abundance of Igf2 receptors and downstream signalling pathways (Pi3k-Akt and Mapk). There was no effect of Jz-ΔICR1 on the expression of targets of the H19-embedded miR-675 or on fetal weight. Our results demonstrate that ICR1 controls placental endocrine capacity via sex-dependent changes in signalling.

Mechanism of neutrophil extracellular traps generation and their role in trophoblasts apoptosis in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a metabolic syndrome occurring in pregnant women and increases the risk of placental dysplasia. Neutrophil extracellular traps (NETs) may play a critical role in placental dysplasia. NETosis (neutrophil cell death by NET release) depends on NADPH/ROS pathway. In view of the adiponectin which is widely believed to be reduced in GDM patients suppresses NADPH oxidase and ROS generation of neutrophil. We speculate that increased NET release is associated with hypoadiponectinemia. Trophoblast apoptosis is significantly increased in GDM patients, but it is not clear whether NETs promotes cell apoptosis. This study aims to reveal the mechanism of Neutrophil Extracellular Traps generation and their role in trophoblast apoptosis in Gestational Diabetes Mellitus. We investigated the generation of NETs by cell-free DNA (cf-DNA) quantification, live-cell imaging, and reactive oxygen species (ROS) measurement. ERK1/2 and p38 MAPK signalling pathway proteins were detected by western blotting. The Cell Counting Kit-8 (CCK-8) assay, flow cytometry, and western blotting were performed to explore the effects of NETs on trophoblast apoptosis. We found that adiponectin inhibited NET release by suppressing ROS production, and p38 MAPK and ERK1/2 proteins were involved in the process. Further, NETs promoted trophoblast apoptosis by activating the ROS-dependent mitochondrial pathway, which is mediated by ERK1/2 signalling. The current study demonstrated that hypoadiponectinemia is the cause of NETs formation and NETs promoting trophoblast apoptosis.

Forced Suppression of let-7a-5p in Mouse Blastocysts Improves Implantation Rate

Embryo implantation requires appropriate communication between the blastocyst and endometrium. Recurrent implantation failure is an essential component of assisted reproductive technology. Also, miRNA-mediated gene expression impacts the implantation process, and the downregulation of some miRs, such as mmu-let-7a, improves this process. In the present study, we evaluated the effect of let-7a forced suppression on the mouse implantation rate. In total, 100 adult female mice and 10 adult male mice were included (Strain CD-1). We analysed the expression of let-7a and its potential mRNAs targets (Igf1, Il1a, Itgb3 and Tgfb1) in control, sham and antagomir-treated blastocysts using quantitative reverse transcription PCR (qRT-PCR). The control and treated blastocysts were transferred to the 20 pseudopregnant mice so that the effect of let-7a suppression on the rate of implantation could be determined. The expression level of let-7a in the treatment group was significantly downregulated (P=0.001) In contrast, no significant expression changes were observed for let-7a or mRNAs targets when the sham and control groups were compared (P>0.05). In comparison to the controls, the antagomir-treated group exhibited significantly upregulated expression levels of Igf1 (0.0167), Itgb3 (0.045) and Tgfb1 (0.0115). Additionally, the implantation rate was significantly higher in the treatment group (78%) than the control group (61%) (P=0.0098). We found that forced suppression of mmu-let-7a-5p through successful transfection of Anti-miR leads to upregulation of downstream genes, Igf1, Itgb3 and Tgfb1, which directly involved in the trophoblast-endometrium attachment and improve the implantation rate.

Expression and significance of microRNA-126 and VCAM-1 in placental tissues of women with early-onset preeclampsia

Objective

To investigate the expression of microRNA‐126 (miR‐126) and vascular endothelial cell adhesion molecule‐1 (VCAM‐1) in the placental tissues of women with early‐onset preeclampsia (EOPE) and their effects on trophoblast invasion.

Materials and Methods

The placental tissues of 30 pregnant women with EOPE who delivered in the Third Affiliated Hospital of Zhengzhou University from November 2019 to May 2020 were selected as the preeclampsia (PE) group, and the placental tissues of 30 healthy pregnant women with normal prenatal examination were selected as the normal group. Immunohistochemistry was used to localize VCAM‐1 in placental tissues，the expression of miR‐126 and VCAM‐1 in placenta tissues of two groups and HTR‐8/SVneo cells transfected with miR‐126 were detected by real‐time polymerase chain reaction (RT‐PCR) and Western blot, and the correlation between them was analyzed. The invasion ability of cells transfected with miR‐126 was observed by Transwell invasion test.

Results

Compared with the normal group, the expression of miR‐126 was higher and VCAM‐1 was lower in the placental tissues of the PE group, and the difference were statistically significant (p < 0.01). Moreover, VCAM‐1 was negatively correlated with the expression of miR‐126 (r = −0.391, p < 0.05). In vitro experiment, the expression level of VCAM‐1 in miR‐126 mimics transfection group was decreased, and the expression level of VCAM‐1 in miR‐126 inhibitor transfection group was increased; the invasion ability of HTR‐8/SVneo cells transfected with miR‐126 mimics was decreased, and the invasion ability of HTR‐8/SVneo cells transfected with miR‐126 inhibitor was enhanced.

Conclusion

There was a negative correlation between the expression of miR‐126 and VCAM‐1 in EOPE.MiR‐126 and VCAM‐1 may participate in the occurrence and development of EOPE by affecting the invasion ability of trophoblast cells.

MicroRNA-126 suppresses the invasion of trophoblast-model JEG-3 cells by targeting LIN28A

Inadequate trophoblast invasion and impaired trophoblast-induced vascular remodeling are features of preeclampsia. In this context, an angiogenesis-related microRNA, miR-126, is abnormally expressed in preeclampsia placentas, but its role in trophoblast development remains unclear. The purpose of this study was to investigate the roles of miR-126 in the proliferation, migration, and invasion processes of trophoblast cells using the human choriocarcinoma-derived JEG-3 cell line as a model. The mRNA expression profiling of JEG-3 cells with and without miR-126 overexpression, in combination with bioinformatics analysis, identified LIN28A as a putative target of miR-126. The results of real-time RT-PCR and luciferase assay were consistent with this idea. Overexpression of miR-126 in JEG-3 cells decreased the invasive ability of the cells without affecting proliferation or migration. The invasiveness of JEG-3 cells was significantly reduced to a similar extent by knockdown of LIN28A with siRNA and by miR-126-overexpression-induced downregulation of LIN28A, although the level of LIN28A protein was much lower in the siLIN28A-transfected cells. These results indicate that miR-126 suppresses JEG-3 cell invasion by targeting LIN28A, and suggest that miR-126-mediated downregulation of LIN28A might contribute to the onset/deterioration of preeclampsia.

Downregulation of miR-126-3p expression contributes to increased inflammatory response in placental trophoblasts in preeclampsia

MiR-126-3p is a prototype of an endothelial miRNA and has protective effects on endothelial cells. However, little is known about the effects of miR-126-3p on placental trophoblasts. In the present study, we tested the hypothesis that aberrant miR-126-3p expression is present in preeclamptic placenta which contributes to increased inflammatory response in trophoblasts. Placentas were obtained immediately after delivery from normotensive and preeclamptic pregnancies. Villous tissue was either fixed with formalin or used for trophoblast isolation. Trophoblast miR-126-3p expression was assessed by in situ hybridization of formalin-fixed tissue sections and by RT-PCR in cultured syncytiotrophoblasts. Culture medium was collected for measurement of IL-6, TNFα, and 8-Isoprostane production by ELISA and total cellular protein was collected for evaluation of HIF1α expression by Western blot. Effects of overexpression of miR-126-3p in trophoblasts on cytokine production were tested by transfection of pre-mir-126, a precursor of miR-126, into primary isolated trophoblasts. We found that downregulation of miR-126-3p expression was associated with increased IL-6 and TNFα production in trophoblasts from preeclamptic placentas vs. normal placentas. Moreover, transient overexpression of miR-126-3p significantly reduced IL-6 and TNFα production in trophoblasts from both normal and preeclamptic placentas. We further found that increase in miR-126-3p expression not only suppressed hypoxia-induced increases in IL-6 and TNFα production, but also attenuated hypoxia-induced increases in HIF1α expression and 8-Isoprostane production in trophoblasts cultured under hypoxic condition. These results provide plausible evidence that downregulation of miR-126-3p expression reduces anti-inflammatory and anti-oxidative stress activities in placental trophoblasts in preeclampsia.

MicroRNA-210 regulates placental adaptation to maternal hypoxic stress during pregnancy†

MicroRNA (miR)-210 is a well-known hypoxia-inducible small RNA. Increasing in vitro evidence demonstrates its involvement in regulating multiple behaviors of placental trophoblasts. However, direct in vivo evidence remains lacking. In the present study, we generated a miR-210-deficient mouse strain using CRISPR/Cas9 technology, in which miR-210 expression was markedly deficient in various tissues. Little influence on fertility rate and litter size was observed after the deletion of miR-210 in mice. Continuous exposure of pregnant mice to hypoxia (10.5% O2) from E6.5 to E10.5 or to E18.5 led to reduction in fetal weight, and such fetal weight loss was markedly worsened in miR-210-knockout dams. Analysis of the placental structure demonstrated the reduced expansion of placental spongiotrophoblast layer and hampered development of labyrinth fetal blood vessels in knockout mice compared to the wild-type controls upon hypoxia stimulation. The findings indicate that miR-210 participates in regulating placental adaptation to hypoxic stress during pregnancy.

MiR-193b inhibits autophagy and apoptosis by targeting IGFBP5 in high glucose-induced trophoblasts

INTRODUCTION

Inhibiting apoptosis of trophoblasts in women with gestational diabetes mellitus (GDM) is expected to guarantee adequate nutrition for the fetus and avoid abortion. MiR-193b is one of the most downregulated miRNAs in GDM patients. However, less is known about the role of miR-193b in autophagy and apoptosis in GDM patients.

METHODS

We detected the expression of miR-193b in GDM patients. Then, we cultured human trophoblasts (HTR8 cells) with high glucose (HG) to simulate a diabetic environment in vitro, and further explored the effects of miR-193b on apoptosis and autophagy of HG-treated HTR8 cells.

RESULTS

The expression of miR-193b was significantly downregulated in the peripheral blood of GDM patients compared with healthy controls, and decreased miR-193b caused apparent autophagy and a substantially high apoptosis rate in HG-treated HTR8 cells. These effects were reversed by enhancing miR-193b expression or using the autophagy inhibitor 3-MA. Inhibiting miR-193b induced the pro-autophagic, cytostatic, and pro-apoptotic effects reduced by 3-MA in HTR8 cells upon HG treatment. Moreover, the expression of insulin-like growth factor-binding protein 5 (IGFBP5) was upregulated notably in the peripheral blood of GDM patients, and IGFBP5 appears to represent a direct miR-193b target. Note that silencing IGFBP5 blocked autophagy and apoptosis in HG-treated HTR8 cells, an effect that was diminished by inhibiting miR-193b.

CONCLUSION

Our data indicate that aberrantly low expression of miR-193b in HG-induced trophoblasts results in massive apoptosis events by upregulating IGFBP5-induced autophagy, which may trigger GDM. Therefore, miR-193b may became a potential target for GDM therapy.