MicroRNA regulation of mitogenic signaling networks in the human placenta

The prenatal diagnostic indicators of placenta accreta spectrum disorders

Placenta accreta spectrum (PAS) disorders refers to a heterogeneous group of anomalies distinguished by abnormal adhesion or invasion of chorionic villi through the myometrium and uterine serosa. PAS frequently results in life-threatening complications, including postpartum hemorrhage and hysterotomy. The incidence of PAS has increased recently as a result of rising cesarean section rates. Consequently, prenatal screening for PAS is essential. Despite the need to increase specificity, ultrasound is still considered a primary adjunct. Given the dangers and adverse effects of PAS, it is necessary to identify pertinent markers and validate indicators to improve prenatal diagnosis. This article summarizes the predictors regarding biomarkers, ultrasound indicators, and magnetic resonance imaging (MRI) features. In addition, we discuss the effectiveness of joint diagnosis and the most recent research on PAS. In particular, we focus on (a) posterior placental implantation and (b) accreta after in vitro fertilization-embryo transfer, both of which have low diagnostic rates. At last, we graphically display the prenatal diagnostic indicators and each diagnostic performance.

A burst of genomic innovation at the origin of placental mammals mediated embryo implantation

The origin of embryo implantation in mammals ~148 million years ago was a dramatic shift in reproductive strategy, yet the molecular changes that established mammal implantation are largely unknown. Although progesterone receptor signalling predates the origin of mammals and is highly conserved in, and critical for, successful mammal pregnancy, it alone cannot explain the origin and subsequent diversity of implantation strategies throughout the placental mammal radiation. MiRNAs are known to be flexible and dynamic regulators with a well-established role in the pathophysiology of mammal placenta. We propose that a dynamic core microRNA (miRNA) network originated early in placental mammal evolution, responds to conserved mammal pregnancy cues (e.g. progesterone), and facilitates species-specific responses. Here we identify 13 miRNA gene families that arose at the origin of placental mammals and were subsequently retained in all descendent lineages. The expression of these miRNAs in response to early pregnancy molecules is regulated in a species-specific manner in endometrial epithelia of species with extreme implantation strategies (i.e. bovine and human). Furthermore, this set of miRNAs preferentially target proteins under positive selective pressure on the ancestral eutherian lineage. Discovery of this core embryo implantation toolkit and specifically adapted proteins helps explain the origin and evolution of implantation in mammals.

Role of microRNAs in trophoblast invasion and spiral artery remodeling: Implications for preeclampsia

It is now well-established that microRNAs (miRNAs) are important regulators of gene expression. The role of miRNAs in placental development and trophoblast function is constantly expanding. Trophoblast invasion and their ability to remodel uterine spiral arteries are essential for proper placental development and successful pregnancy outcome. Many miRNAs are reported to be dysregulated in pregnancy complications, especially preeclampsia and they exert various regulatory effects on trophoblasts. In this review, we provide a brief overview of miRNA biogenesis and their mechanism of action, as well as of trophoblasts differentiation, invasion and spiral artery remodeling. We then discuss the role of miRNAs in trophoblasts invasion and spiral artery remodeling, focusing on miRNAs that have been thoroughly investigated, especially using multiple model systems. We also discuss the potential role of miRNAs in the pathogenesis of preeclampsia.

miR-514a-3p: a novel SHP-2 regulatory miRNA that modulates human cytotrophoblast proliferation

Src homology-2 domain-containing protein tyrosine phosphatase 2 (SHP-2), encoded by the PTPN11 gene, forms a central component of multiple signalling pathways and is required for insulin-like growth factor (IGF)-induced placental growth. Altered expression of SHP-2 is associated with aberrant placental and fetal growth indicating that drugs modulating SHP-2 expression may improve adverse pregnancy outcome associated with altered placental growth. We have previously demonstrated that placental PTPN11/SHP-2 expression is controlled by miRNAs. SHP-2 regulatory miRNAs may have therapeutic potential; however, the individual miRNA(s) that regulate SHP-2 expression in the placenta remain to be established. We performed in silico analysis of 3'UTR target prediction databases to identify libraries of Hela cells transfected with individual miRNA mimetics, enriched in potential SHP-2 regulatory miRNAs. Analysis of PTPN11 levels by quantitative (q) PCR revealed that miR-758-3p increased, while miR-514a-3p reduced PTPN11 expression. The expression of miR-514a-3p and miR-758-3p within the human placenta was confirmed by qPCR; miR-514a-3p (but not miR-758-3p) levels inversely correlated with PTPN11 expression. To assess the interaction between these miRNAs and PTPN11/SHP-2, specific mimetics were transfected into first-trimester human placental explants and then cultured for up to 4 days. Overexpression of miR-514a-3p, but not miR-758-3p, significantly reduced PTPN11 and SHP-2 expression. microRNA-ribonucleoprotein complex (miRNP)-associated mRNA assays confirmed that this interaction was direct. miR-514a-3p overexpression attenuated IGF-I-induced trophoblast proliferation (BrdU incorporation). miR-758-3p did not alter trophoblast proliferation. These data demonstrate that by modulating SHP-2 expression, miR-514a-3p is a novel regulator of IGF signalling and proliferation in the human placenta and may have therapeutic potential in pregnancies complicated by altered placental growth.

Novel Technologies for Target Delivery of Therapeutics to the Placenta during Pregnancy: A Review

Uterine spiral artery remodeling is essential for placental perfusion and fetal growth and, when impaired, results in placental ischemia and pregnancy complications, e.g., fetal growth restriction, preeclampsia, premature birth. Despite the high incidence of adverse pregnancies, current treatment options are limited. Accordingly, research has shifted to the development of gene therapy technologies that provide targeted delivery of "payloads" to the placenta while limiting maternal and fetal exposure. This review describes the current strategies, including placental targeting peptide-bound liposomes, nanoparticle or adenovirus constructs decorated with specific peptide sequences and placental gene promoters delivered via maternal IV injection, directly into the placenta or the uterine artery, as well as noninvasive site-selective targeting of regulating genes conjugated with microbubbles via contrast-enhanced ultrasound. The review also provides a perspective on the effectiveness of these technologies in various animal models and their practicability and potential use for targeted placental delivery of therapeutics and genes in adverse human pregnancies affected by placental dysfunction.

High-throughput miRNA sequencing of the human placenta: expression throughout gestation

Aim: To understand miRNA changes across gestation in healthy human placentae. This is essential before miRNAs can be used as biomarkers or prognostic indicators during pregnancy. Materials & methods: Using next-generation sequencing, we characterize the normative human placenta miRNome in first (n = 113) and third trimester (n = 47). Results & conclusion: There are 801 miRNAs expressed in both first and third trimester, including 182 with similar expression across gestation (p ≥ 0.05, fold change ≤2) and 180 significantly different (false discovery rate <0.05, fold change >2). Of placenta-specific miRNA clusters, chromosome 14 miRNA cluster decreases across gestation and chromosome 19 miRNA cluster is overall highly expressed. Chromosome 13 clusters are upregulated in first trimester. This work provides a rich atlas of healthy pregnancies to direct functional studies investigating the epigenetic differences in first and third trimester placentae.

Cell dynamics in human villous trophoblast

BACKGROUND

Villous cytotrophoblast (vCTB) is a precursor cell population that supports the development of syncytiotrophoblast (vSTB), the high surface area barrier epithelium of the placental villus, and the primary interface between maternal and fetal tissue. In light of increasing evidence that the placenta can adapt to changing maternal environments or, under stress, can trigger maternal disease, we consider what properties of these cells empower them to exert a controlling influence on pregnancy progression and outcome.

OBJECTIVE AND RATIONALE

How are cytotrophoblast proliferation and differentiation regulated in the human placental villus to allow for the increasing demands of the fetal and environmental challenges and stresses that may arise during pregnancy?

SEARCH METHODS

PubMed was interrogated using relevant keywords and word roots combining trophoblast, villus/villous, syncytio/syncytium, placenta, stem, transcription factor (and the individual genes), signalling, apoptosis, autophagy (and the respective genes) from 1960 to the present. Since removal of trophoblast from its tissue environment is known to fundamentally change cell growth and differentiation kinetics, research that relied exclusively on cell culture has not been the main focus of this review, though it is mentioned where appropriate. Work on non-human placenta is not systematically covered, though mention is made where relevant hypotheses have emerged.

OUTCOMES

The synthesis of data from the literature has led to a new hypothesis for vCTB dynamics. We propose that a reversible transition can occur from a reserve population in G0 to a mitotically active state. Cells from the in-cycle population can then differentiate irreversibly to intermediate cells that leave the cycle and turn on genes that confer the capacity to fuse with the overlying vSTB as well as other functions associated with syncytial barrier and transport function. We speculate that alterations in the rate of entry to the cell cycle, or return of cells in the mitotic fraction to G0, can occur in response to environmental challenge. We also review evidence on the life cycle of trophoblast from the time that fusion occurs, and point to gaps in knowledge of how large quantities of fetal DNA arrive in maternal circulation. We critique historical methodology and make a case for research to re-address questions about trophoblast lifecycle and dynamics in normal pregnancy and the common diseases of pre-eclampsia and fetal growth restriction, where altered trophoblast kinetics have long been postulated.

WIDER IMPLICATIONS

The hypothesis requires experimental testing, moving research away from currently accepted methodology towards a new standard that includes representative cell and tissue sampling, assessment of cell cycle and differentiation parameters, and robust classification of cell subpopulations in villous trophoblast, with due attention to gestational age, maternal and fetal phenotype, disease and outcome.

The impact of microRNAs on myeloid-derived suppressor cells in cancer

Inflammation promotes cancer development. To a large extent, this can be attributed to the recruitment of myeloid-derived suppressor cells (MDSCs) to tumors. These cells are known for establishing an immunosuppressive tumor microenvironment by suppressing T cell activities. However, MDSCs also promote metastasis and angiogenesis. Critically, as small non-coding RNAs that regulate gene expression, microRNAs (miRNAs) control MDSC activities. In this review, we discuss how miRNA networks regulate key MDSC signaling pathways, how they shape MDSC development, differentiation and activation, and how this impacts tumor development. By targeting the expression of miRNAs in MDSCs, we can alter their main signaling pathways. In turn, this can compromise their ability to promote multiple hallmarks of cancer. Therefore, this may represent a new powerful strategy for cancer immunotherapy.

Role of MicroRNA-145 in DNA Damage Signalling and Senescence in Vascular Smooth Muscle Cells of Type 2 Diabetic Patients

Increased cardiovascular morbidity and mortality in individuals with type 2 diabetes (T2DM) is a significant clinical problem. Despite advancements in achieving good glycaemic control, this patient population remains susceptible to macrovascular complications. We previously discovered that vascular smooth muscle cells (SMC) cultured from T2DM patients exhibit persistent phenotypic aberrancies distinct from those of individuals without a diagnosis of T2DM. Notably, persistently elevated expression levels of microRNA-145 co-exist with characteristics consistent with aging, DNA damage and senescence. We hypothesised that increased expression of microRNA-145 plays a functional role in DNA damage signalling and subsequent cellular senescence specifically in SMC cultured from the vasculature of T2DM patients. In this study, markers of DNA damage and senescence were unambiguously and permanently elevated in native T2DM versus non-diabetic (ND)-SMC. Exposure of ND cells to the DNA-damaging agent etoposide inflicted a senescent phenotype, increased expression of apical kinases of the DNA damage pathway and elevated expression levels of microRNA-145. Overexpression of microRNA-145 in ND-SMC revealed evidence of functional links between them; notably increased secretion of senescence-associated cytokines and chronic activation of stress-activated intracellular signalling pathways, particularly the mitogen-activated protein kinase, p38α. Exposure to conditioned media from microRNA-145 overexpressing cells resulted in chronic p38α signalling in naïve cells, evidencing a paracrine induction and reinforcement of cell senescence. We conclude that targeting of microRNA-145 may provide a route to novel interventions to eliminate DNA-damaged and senescent cells in the vasculature and to this end further detailed studies are warranted.

Profiling circulating microRNAs in the serum of pregnant and non-pregnant pigs reveals a plethora of reproductive status-dependent microRNAs

Circulating, non-coding RNAs, such as microRNAs (miRNAs) have been proposed to be powerful pathophysiological indicators of pregnancy in animals and humans. Since their discovery, it is known that miRNAs can take part in numerous biological processes, including cell proliferation and differentiation during early embryonic development and establishment of pregnancy. Our recent studies have indicated that maternal blood can carry miRNAs reported previously at the embryo-maternal interface in pigs. To expand the scope of our research, we tested the hypothesis that miRNAs previously identified in conceptuses, trophoblasts, endometrium and uterine lumen-derived extracellular vesicles (EVs) collected before Day 20 of pregnancy can show reproductive status-dependent profiles in the serum of cyclic and pregnant crossbred pigs. Custom-designed TaqMan arrays, multiplex real-time reverse transcription (RT)-PCR and real-time RT-PCR allowed us to identify a number of reproductive status-dependent miRNAs in serum samples collected from pigs during the estrous cycle or pregnancy (Days 16 and 20). We found that serum samples were enriched with miRNAs involved in processes important during the estrous cycle and early pregnancy, e.g. cell sensitivity and viability, angiogenesis, embryonic cell proliferation and differentiation. Further validation revealed different abundance of ssc-miR-143-3p and ssc-miR-125b in pregnant and non-pregnant animals and correlation of ssc-miR-125b levels with litter size. In addition, analyzed serum samples contained both EVs and Argonaute2 proteins, which are known to be involved in miRNA transportation and intercellular communication. In summary, we identified several circulating miRNAs that differ in abundance between cyclic and pregnant animals and could serve as potential indicators of reproductive status in pigs during breeding management.

MicroRNA-Mediated Gene Regulatory Mechanisms in Mammalian Female Reproductive Health

Mammalian reproductive health affects the entire reproductive cycle starting with the ovarian function through implantation and fetal growth. Various environmental and physiological factors contribute to disturbed reproductive health status leading to infertility problems in mammalian species. In the last couple of decades a significant number of studies have been conducted to investigate the transcriptome of reproductive tissues and organs in relation to the various reproductive health issues including endometritis, polycystic ovarian syndrome (PCOS), intrauterine growth restriction (IUGR), preeclampsia, and various age-associated reproductive disorders. Among others, the post-transcriptional regulation of genes by small noncoding miRNAs contributes to the observed transcriptome dysregulation associated with reproductive pathophysiological conditions. MicroRNAs as a class of non-coding RNAs are also known to be involved in various pathophysiological conditions either in cellular cytoplasm or they can be released to the extracellular fluid via membrane-bounded extracellular vesicles and proteins. The present review summarizes the cellular and extracellular miRNAs and their association with the etiology of major reproductive pathologies including PCOS, endometritis, IUGR and age-associated disorders in various mammalian species.

miR-193a-3p Mediates Placenta Accreta Spectrum Development by Targeting EFNB2 via Epithelial-Mesenchymal Transition Pathway Under Decidua Defect Conditions

Objective: To clarify the role of microRNA-193a-3p (miR-193a-3p) in the pathogenesis of placenta accreta spectrum.

Methods: The placental tissue expression levels of miR-193a-3p and Ephrin-B2 (EFNB2) were compared between a placenta accreta spectrum group and a control group. Transwell migration and invasion assays were used to verify the effect of miR-193a-3p and EFNB2 on HTR-8/SVneo cells cultured in human endometrial stromal cell (hESC)-conditioned medium. Epithelial-mesenchymal transition (EMT)-related proteins were examined by western blotting to establish whether the EMT pathway was altered in placenta accreta spectrum. To determine whether EFNB2 is a target gene of miR-193a-3p, luciferase activity assays were performed.

Results: miR-193a-3p was upregulated but EFNB2 downregulated in the placenta accreta spectrum group and EFNB2 was a direct target of miR-193a-3p. Overexpression or inhibition of miR-193a-3p revealed that miR-193a-3p promoted the migration and invasion of HTR-8/SVneo cells cultured in hESC-conditioned medium. Furthermore, EMT was induced, as shown by increased N-cadherin, vimentin, MMP2, and MMP9 and decreased E-cadherin in the placenta accreta spectrum group and in HTR-8/SVneo cells transfected with miR-193a-3p mimics or si-EFNB2. The negative effect of miR-193a-3p inhibitor was reversed by co-transfection with si-EFNB2 in function studies and in analyses of EMT-related proteins in vitro.

Conclusion: miR-193a-3p which upregulated in placenta accreta spectrum group increases HTR-8/SVneo cell migration and invasion by targeting EFNB2 via the EMT pathway under decidua defect conditions to lead to placenta accreta spectrum.

Development and validation of a four-microRNA signature for placenta accreta spectrum: an integrated competing endogenous RNA network analysis

Background

Placenta accreta spectrum (PAS) is a major cause of maternal morbidity and mortality in modern obstetrics, however, few studies have explored the underlying molecular mechanisms and biomarkers. In this study, we aimed to elucidate the regulatory RNA network contributing to PAS, comprising long non-coding (lnc), micro (mi), and messenger (m) RNAs, and identify biomarkers for the prediction of intraoperative blood volume loss.

Methods

Using RNA sequencing, we compared mRNA, lncRNA, and miRNA expression profiles between five PAS and five normal placental tissues. Furthermore, the miRNA expression profiles in maternal plasma samples from ten PAS and ten control participants were assessed. The data and clinical information were analyzed using R language and GraphPad Prism 7 software.

Results

Upon comparing PAS and control placentas, we identified 8,806 lncRNAs, 128 miRNAs, and 1,788 mRNAs that were differentially expressed. Based on a lasso regression analysis and correlation predictions, we developed a competing endogenous (ce) RNA network comprising 20 lncRNAs, 4 miRNAs, and 19 mRNAs. This network implicated a reduced angiogenesis pathway in PAS, and correlation analyses indicated that two miRNAs (hsa-miR‐490-3p and hsa-miR-133a-3p) were positively correlated to operation-related blood volume loss.

Conclusions

We identified a ceRNA regulatory mechanism in PAS, and two miRNAs that may potentially serve as biomarkers of PAS prognosis.

From animal models to patients: the role of placental microRNAs, miR-210, miR-126, and miR-148a/152 in preeclampsia

Placental microRNAs (miRNAs) regulate the placental transcriptome and play a pathological role in preeclampsia (PE), a hypertensive disorder of pregnancy. Three PE rodent model studies explored the role of placental miRNAs, miR-210, miR-126, and miR-148/152 respectively, by examining expression of the miRNAs, their inducers, and potential gene targets. This review evaluates the role of miR-210, miR-126, and miR-148/152 in PE by comparing findings from the three rodent model studies with in vitro studies, other animal models, and preeclamptic patients to provide comprehensive insight into genetic components and pathological processes in the placenta contributing to PE. The majority of studies demonstrate miR-210 is upregulated in PE in part driven by HIF-1α and NF-κBp50, stimulated by hypoxia and/or immune-mediated processes. Elevated miR-210 may contribute to PE via inhibiting anti-inflammatory Th2-cytokines. Studies report an up- and downregulation of miR-126, arguably reflecting differences in expression between cell types and its multifunctional capacity. MiR-126 may play a pro-angiogenic role by mediating the PI3K-Akt pathway. Most studies report miR-148/152 family members are upregulated in PE. Evidence suggests they may inhibit DNA methylation of genes involved in metabolic and inflammatory pathways. Given the genetic heterogeneity of PE, it is unlikely that a single placental miRNA is a suitable therapeutic target for all patients. Investigating miRNAs in PE subtypes in patients and animal models may represent a more appropriate approach going forward. Developing methods for targeting placental miRNAs and specific placental cell types remains crucial for research seeking to target placental miRNAs as a novel treatment for PE.

MicroRNAs in Uteroplacental Vascular Dysfunction

Pregnancy complications of preeclampsia and intrauterine growth restriction (IUGR) are major causes of maternal and perinatal/neonatal morbidity and mortality. Although their etiologies remain elusive, it is generally accepted that they are secondary to placental insufficiency conferred by both failure in spiral artery remodeling and uteroplacental vascular malfunction. MicroRNAs (miRNAs) are small no-coding RNA molecules that regulate gene expression at the post-transcriptional level. Increasing evidence suggests that miRNAs participate in virtually all biological processes and are involved in numerous human diseases. Differentially expressed miRNAs in the placenta are typical features of both preeclampsia and IUGR. Dysregulated miRNAs target genes of various signaling pathways in uteroplacental tissues, contributing to the development of both complications. In this review, we provide an overview of how aberrant miRNA expression in preeclampsia and IUGR impacts the expression of genes involved in trophoblast invasion and uteroplacental vascular adaptation.

Expression and clinical significance of miRNA-145 and miRNA-218 in laryngeal cancer

Expression of miRNA-145 and miRNA-218 in serum of patients with laryngeal cancer and the relationship between them and the clinicopathological parameters and prognosis were investigated. The clinical medical records of 132 patients with laryngeal cancer, who were admitted to Guangdong Second Provincial General Hospital from February 2009 to March 2014, were retrospectively analyzed and comprised the study group. The data of physical examinations of 56 healthy volunteers who took physical examinations in the same hospital comprised the control group. RT-qPCR was used to detect the expression levels of miRNA-145 and miRNA-218 in serum of the patients in the two groups. According to the relative expression levels of miRNA-145 and miRNA-218 in serum of the patients in the study group on the day when they left hospital, the study group was divided into the high expression group (n=73 patients) and the low expression group (n=59 patients). The patients received a 48-month follow-up visit and their survival condition was recorded and the Kaplan-Meier was used to carry out the survival analysis. The expression levels of miRNA-145 and miRNA-218 in serum of the patients in the study group were lower than those in the control group (P<0.05). The median survival time of the patients in the high expression group was 30 months while the median survival time of the patients in the low expression group was 26 months. The expression levels of miRNA-145 and miRNA-218 in serum of patients with laryngeal cancer decreased, the higher the expression levels of miRNA-145 and miRNA-218 in serum of patients with laryngeal cancer were, the better the prognosis was. miRNA-145 and miRNA-218 were used as indicators of assessing the prognosis of patients with laryngeal cancer.

Imprinted MicroRNA Gene Clusters in the Evolution, Development, and Functions of Mammalian Placenta

In mammals, the expression of a subset of microRNA (miRNA) genes is governed by genomic imprinting, an epigenetic mechanism that confers monoallelic expression in a parent-of-origin manner. Three evolutionarily distinct genomic intervals contain the vast majority of imprinted miRNA genes: the rodent-specific, paternally expressed C2MC located in intron 10 of the Sfmbt2 gene, the primate-specific, paternally expressed C19MC positioned at human Chr.19q13.4 and the eutherian-specific, maternally expressed miRNAs embedded within the imprinted Dlk1-Dio3 domains at human 14q32 (also named C14MC in humans). Interestingly, these imprinted miRNA genes form large clusters composed of many related gene copies that are co-expressed with a marked, or even exclusive, localization in the placenta. Here, we summarize our knowledge on the evolutionary, molecular, and physiological relevance of these epigenetically-regulated, recently-evolved miRNAs, by focusing on their roles in placentation and possibly also in pregnancy diseases (e.g., preeclampsia, intrauterine growth restriction, preterm birth).

Upregulated microRNAs in membranous glomerulonephropathy are associated with significant downregulation of IL6 and MYC mRNAs

Membranous glomerulonephropathy (MGN) is a glomerulopathy characterized by subepithelial deposits of immune complexes on the extracapillary side of the glomerular basement membrane. Insertion of C5b-9 (complement membrane-attack complex) into the membrane leads to functional impairment of the glomerular capillary wall. Knowledge of the molecular pathogenesis of MGN is actually scanty. MicroRNA (miRNA) profiling in MGN and unaffected tissues was performed by TaqMan Low-Density Arrays. Expression of miRNAs and miRNA targets was evaluated in Real-Time polymerase chain reaction (PCR). In vitro transient silencing of miRNAs was achieved through transfection with miRNA inhibitors. Ten miRNAs (let-7a-5p, let-7b-5p, let-7c-5p, let-7d-5p, miR-107, miR-129-3p, miR-423-5p, miR-516-3p, miR-532-3p, and miR-1275) were differentially expressed (DE) in MGN biopsies compared to unaffected controls. Interleukin 6 (IL6) and MYC messenger RNAs (mRNAs; targets of DE miRNAs) were significantly downregulated in biopsies from MGN patients, and upregulated in A498 cells following let-7a-5p or let-7c-5p transient silencing. Gene ontology analysis showed that DE miRNAs regulate pathways associated with MGN pathogenesis, including cell cycle, proliferation, and apoptosis. A significant correlation between DE miRNAs and mRNAs and clinical parameters (i.e., antiphospholipid antibodies, serum creatinine, estimated glomerular filtration, proteinuria, and serum cholesterol) has been detected. Based on our data, we propose that DE miRNAs and their downstream network may be involved in MGN pathogenesis and could be considered as potential diagnostic biomarkers of MGN.

RNA-sequencing analysis of umbilical cord plasma microRNAs from healthy newborns

MicroRNAs are a class of small non-coding RNA that regulate gene expression at a post-transcriptional level. MicroRNAs have been identified in various body fluids under normal conditions and their stability as well as their dysregulation in disease has led to ongoing interest in their diagnostic and prognostic potential. Circulating microRNAs may be valuable predictors of early-life complications such as birth asphyxia or neonatal seizures but there are relatively few data on microRNA content in plasma from healthy babies. Here we performed small RNA-sequencing analysis of plasma processed from umbilical cord blood in a set of healthy newborns. MicroRNA levels in umbilical cord plasma of four male and four female healthy babies, from two different centres were profiled. A total of 1,004 individual microRNAs were identified, which ranged from 426 to 659 per sample, of which 269 microRNAs were common to all eight samples. Many of these microRNAs are highly expressed and consistent with previous studies using other high throughput platforms. While overall microRNA expression did not differ between male and female cord blood plasma, we did detect differentially edited microRNAs in female plasma compared to male. Of note, and consistent with other studies of this type, adenylation and uridylation were the two most prominent forms of editing. Six microRNAs, miR-128-3p, miR-29a-3p, miR-9-5p, miR-218-5p, 204-5p and miR-132-3p were consistently both uridylated and adenylated in female cord blood plasma. These results provide a benchmark for microRNA profiling and biomarker discovery using umbilical cord plasma and can be used as comparative data for future biomarker profiles from complicated births or those with early-life developmental disorders.

Exploration of the regulation and control mechanisms of miR-145 in trophoblast cell proliferation and invasion

Preeclampsia (PE) is the leading cause of maternal and fetal mortality and morbidity. Furthermore, recent studies have reported that miR-145 within the preeclamptic trophoblast debris may cause the high blood pressure via interacting with the maternal endothelium. The aim of the present study was to investigate the functions of miR-145 in PE. Reverse transcription-quantitative polymerase chain reaction and western blotting were used to assess the expression of miR-145 and mucin (MUC1), respectively. TargetScan, miRBase and miRWalk were used to predict the targets of miR-145. Constructed miR-145 mimic plasmids were transfected into HTR-8/SVneo cells for further experiments, including an MTT assay for cell proliferation, Transwell assay for cell invasion and flow cytometry for cell apoptosis analysis. Additionally, the luciferase reporter gene system was employed for target verification. The results demonstrated that miR-145 is downregulated and MUC1 is upregulated in PE tissues and cells compared with normal placenta tissues and cells. The correlation analysis suggests that the expression of miR-145 is negatively correlated with MUC1. Meanwhile, increased proliferation, enhanced invasion and decreased apoptosis of HTR-8/SVneo cells was observed in miR-145 mimic groups compared with mimic control group. Also, the decreased luciferase activity in the miR-145 mimic group indicates that MUC1 may be a target of miR-145. In summary, the results of the present study suggest that miR-145 may serve key roles in the regulation of trophoblast cell proliferation and invasion by targeting MUC1.

MicroRNAs: crucial regulators of placental development

MicroRNAs (miRNAs) are small non-coding single-stranded RNAs that are integral to a wide range of cellular processes mainly through the regulation of translation and mRNA stability of their target genes. The placenta is a transient organ that exists throughout gestation in mammals, facilitating nutrient and gas exchange and waste removal between the mother and the fetus. miRNAs are expressed in the placenta, and many studies have shown that miRNAs play an important role in regulating trophoblast differentiation, migration, invasion, proliferation, apoptosis, vasculogenesis/angiogenesis and cellular metabolism. In this review, we provide a brief overview of canonical and non-canonical pathways of miRNA biogenesis and mechanisms of miRNA actions. We highlight the current knowledge of the role of miRNAs in placental development. Finally, we point out several limitations of the current research and suggest future directions.

MicroRNA-342 Prohibits Proliferation and Invasion of Melanoma Cells by Directly Targeting Zinc-Finger E-Box-Binding Homeobox 1

As documented in numerous studies, microRNAs (miRNAs) play key roles in various biological processes associated with melanoma occurrence and development. In this study, we found that miRNA-342 (miR-342) was significantly downregulated in melanoma tissues and cell lines. Additionally, the ectopic expression of miR-342 prohibited the cell proliferation and invasion of melanoma. Moreover, zinc-finger E-box-binding homeobox 1 (ZEB1) was identified as a direct target gene of miR-342 in melanoma. Similar with the results induced by miR-342 overexpression, ZEB1 knockdown attenuated cell proliferation and invasion in melanoma. Furthermore, the restoration of ZEB1 expression reversed the suppressive effects of miR-342 on the proliferation and invasion of melanoma cells. These findings suggest that miR-342 may play tumor-suppressing roles in melanoma, at least partially, by directly inhibiting ZEB1 expression. Therefore, miR-342 may be developed as a potential candidate for the treatment of patients with this aggressive type of cancer.

The Destiny of Glucose from a MicroRNA Perspective

Glucose serves as a primary, and for some tissues the unique, fuel source in order to generate and maintain the biological functions. Hyperglycemia is a hallmark of type 2 diabetes and is the direct consequence of perturbations in the glucose homeostasis. Insulin resistance, referred to as a reduced response of target tissues to the hormone, contributes to the development of hyperglycemia. The molecular mechanisms responsible for the altered glucose homeostasis are numerous and not completely understood. MicroRNAs (miRNAs) are now recognized as regulators of the lipid and glucose metabolism and are involved in the onset of metabolic diseases. Indeed, these small non-coding RNA molecules operate in the RNA silencing and posttranscriptional regulation of gene expression and may modulate the levels of kinases and enzymes in the glucose metabolism. Therefore, a better characterization of the function of miRNAs and a deeper understanding of their role in disease may represent a fundamental step toward innovative treatments addressing the causes, not only the symptoms, of hyperglycemia, using approaches aimed at restoring either miRNAs or their specific targets. In this review, we outline the current understanding regarding the impact of miRNAs in the glucose metabolism and highlight the need for further research focused on altered key kinases and enzymes in metabolic diseases.

Identification of potential early biomarkers of preeclampsia

INTRODUCTION

It is thought that poor placental perfusion caused by inadequate remodelling of the maternal spiral arteries leads to preeclampsia (PE). To identify novel signalling pathways that contribute to PE pathogenesis and to create prerequisites for the non-invasive diagnosis of PE before clinical manifestations of the disease, this study aimed to evaluate miRNA expression levels in the placenta and blood plasma of pregnant women.

METHODS

miRNA deep sequencing followed by real-time quantitative RT-PCR was applied to compare miRNA expression profiles in the placenta and blood plasma from women with early- and late-onset PE relative to the control group.

RESULTS

A more than two-fold decrease in miR-532-5p, -423-5p, -127-3p, -539-5p, -519a-3p, and -629-5p and let-7c-5p expression levels was observed in the placenta, while a more than two-fold increase in miR-423-5p, 519a-3p, and -629-5p and let-7c-5p was observed in the blood plasma of pregnant women with PE. The above-listed miRNAs are associated with PE for the first time in this study, except for miR-519a-3p, whose role in PE has already been postulated. Using a logistic regression, plasma samples were classified into the early-onset PE group (probability p = 0.01, 80% specificity, 87.5% sensitivity and 87.5% precision) and showed increased miR-423-5p expression levels that were confirmed by the 9.8-fold up-regulation (р = 0.0002498) of miR-423-5p expression observed in the blood plasma at 11-13 GW by RT-PCR in a group of pregnant women manifesting severe PE clinical signs at 28-33 GW.

CONCLUSIONS

miR-423-5p may be considered a potential candidate for the early diagnosis of PE during the targeted management of high-risk pregnancies.

MiRNA-target network analysis identifies potential biomarkers for Traditional Chinese Medicine (TCM) syndrome development evaluation in hepatitis B caused liver cirrhosis

Hepatitis B is one of most etiologies of Liver cirrhosis in China, and clinically lacks the effective strategy for Hepatitis B caused cirrhosis (HBC) therapy. As a complementary and alternative medicine, Chinese Traditional Medicine (TCM) has special therapeutic effects for HBC. Here, we focus on the evolution process of HBC TCM syndromes, which was from Excessive (Liver-Gallbladder Dampness-Heat Syndrome, LGDHS) to Deficient (Liver-Kidney Deficiency Syndrome, LKYDS) via Excessive-Deficient syndrome (Liver-Depression and Spleen-Deficiency Syndrome, LDSDS). Using R package, 16 miRNAs in LGDHS/Normal, 48 miRNAs in LDSDS/LGDHS, and 16 miRNAs in LKYDS/LDSDS were identified, respectively. The miRNA-target networks show that the LDSDS was most stability and complicated. Subsequently, 4 kernel miRNAs with LGDHS-LDSDS process, and 5 kernel miRNAs with LDSDS-LKYDS process were screened. Using RT-qPCR data, p1 (hsa-miR-17-3p, -377-3p, -410-3p and -495) and p2 miRNA panel (hsa-miR-377-3p, -410-3p, -27a-3p, 149-5p and 940) were identified by Logistic Regression Model, which clearly improve the accuracy of TCM syndrome classification. The rebuilt miRNA-target network shows that the LDSDS is a critical point and might determine the evolution directions of HBC TCM syndrome. This study suggests that the identified kernel miRNAs act as potential biomarkers and benefit to evaluate the evolution tendency of HBC TCM syndromes.

Let-7a inhibits migration, invasion and tumor growth by targeting AKT2 in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common endocrine malignancy. Increasing evidence showed that microRNAs (miRNAs) play an important role in the PTC progression. In our study, the result showed that let-7a is significantly downregulated in PTC tissues and thyroid cancer cell lines. Overexpression of let-7a suppressed PTC cell proliferation, migration and invasion. Interestingly, we found that AKT2 was a direct target of let-7a and the expression levels of AKT2 were also observed to inversely correlate with let-7a expression in PTC tissues. Furthermore, enhancing AKT2 expression partially reversed the inhibitory effects of let-7a in PTC. Taken together, these findings suggest that let-7a acts as a novel suppressor by targeting the AKT2 gene and might be a candidate target for the development of novel therapeutic strategies to treat papillary thyroid carcinoma.

Placental Homing Peptide-microRNA Inhibitor Conjugates for Targeted Enhancement of Intrinsic Placental Growth Signaling

Suboptimal placental growth and development are the underlying cause of many pregnancy complications. No treatments are available, primarily due to the risk of causing fetal teratogenicity. microRNAs (miRNAs) are short, non-coding RNA sequences that regulate multiple downstream genes; miR-145 and miR675 have previously been identified as negative regulators of placental growth. In this proof of principle study, we explored the feasibility of delivering miRNA inhibitors to the placentas of pregnant mice and developed novel placental homing peptide-microRNA inhibitor conjugates for targeted enhancement of intrinsic placental growth signalling. Scrambled-, miR-145- or miR-675 inhibitor sequences were synthesised from peptide nucleic acids and conjugated to the placental homing peptide CCGKRK. Intravenous administration of the miR-145- and miR-675 conjugates to pregnant C57BL/6J mice significantly increased fetal and placental weights compared to controls; the miR-675 conjugate significantly reduced placental miR-675 expression. When applied to human first trimester placental explants, the miR-145 conjugate significantly reduced placental miR-145 expression, and both conjugates induced significant enhancement of cytotrophoblast proliferation; no effect was observed in term placental explants. This study demonstrates that homing peptide-miRNA inhibitor conjugates can be exploited to promote placental growth; these novel therapeutics may represent an innovative strategy for targeted treatment of compromised placental development.

Genes, epigenetics and miRNA regulation in the placenta

This text reviews briefly the context in which epigenetics regulate gene expression in trophoblast development and function. It is an attempt to focus on a limited number of recent papers that, according to the author, shed new light on placental development, and constitute possible trails for improving knowledge and women follow-up in pathological pregnancies.

Influence of gestational diabetes mellitus on human umbilical vein endothelial cell miRNA

We aimed to identify miRNAs whose expression levels in fetal tissues are altered by exposure to a diabetic milieu and elucidate the impact on target protein expression. Gestational diabetes mellitus (GDM) affects both immediate and future disease risk in the offspring. We hypothesized that GDM alters miRNA expression in human umbilical vein endothelial cells (HUVECs) that may influence metabolic processes. A cross-sectional design compared differences in miRNA expression in HUVECs and target protein abundance in placentae between infants of women with GDM (IGDM) and infants born to normoglycaemic controls. miRNAs were identified using microarray profiling and literature review and validated by quantitative PCR (qPCR). In vitro transfection studies explored the impact of the miRNA on target protein expression. Expression of seven miRNA species, miR-30c-5p, miR-452-5p, miR-126-3p, miR-130b-3p, miR-148a-3p, miR-let-7a-5p and miR-let-7g-5p, was higher in the HUVECs of IGDM. Abundance of the catalytic subunit of AMP-activated protein kinase α1 (AMPKα1) was decreased in the HUVECs and BeWo cells (transformed trophoblast cell line) transfected with miR-130b and miR-148a mimics. AMPKα1 expression was also decreased in placental tissues of IGDM. The expression of several miRNAs were altered by in utero exposure to DM in infants of women whose dysglycaemia was very well controlled by current standards. Decreased expression of AMPKα1 as a result of increased levels of miR-130b and miR-148a may potentially explain the decrease in fat oxidation we reported in infants at 1 month of age and, if persistent, may predispose offspring to future metabolic disease.

Systematic Review of Micro-RNA Expression in Pre-Eclampsia Identifies a Number of Common Pathways Associated with the Disease

Background

Pre-eclampsia (PE) is a complex, multi-systemic condition of pregnancy which greatly impacts maternal and perinatal morbidity and mortality. MicroRNAs (miRs) are differentially expressed in PE and may be important in helping to understand the condition and its pathogenesis.

Methods

Case-control studies investigating expression of miRs in PE were collected through a systematic literature search. Data was extracted and compared from 58 studies to identify the most promising miRs associated with PE pathogenesis and identify areas of methodology which could account for often conflicting results.

Results

Some of the most frequently differentially expressed miRs in PE include miR-210, miR-223 and miR-126/126* which associate strongly with the etiological domains of hypoxia, immunology and angiogenesis. Members of the miR-515 family belonging to the imprinted chromosome 19 miR cluster with putative roles in trophoblast invasion were also found to be differentially expressed. Certain miRs appear to associate with more severe forms of PE such as miR-210 and the immune-related miR-181a and miR-15 families. Patterns of miR expression may help pinpoint key pathways (e.g. IL-6/miR-223/STAT3) and aid in untangling the heterogeneous nature of PE. The detectable presence of many PE-associated miRs in antenatal circulatory samples suggests their usefulness as predictive biomarkers. Further progress in ascertaining the clinical value of miRs and in understanding how they might contribute to pathogenesis is predicated upon resolving current methodological challenges in studies. These include differences in diagnostic criteria, cohort characteristics, sampling technique, RNA isolation and platform-dependent variation in miR profiling.

Conclusion

Reviewing studies of PE-associated miRs has revealed their potential as informants of underlying target genes and pathways relating to PE pathogenesis. However, the incongruity in results across current studies hampers their capacity to be useful biomarkers of the condition.

MiR-145 suppresses embryo-epithelial juxtacrine communication at implantation by modulating maternal IGF1R

Successful implantation requires the synchronization of viable embryonic development with endometrial receptivity. The mechanisms allowing for the initiation of crosstalk between the embryo and the endometrium remain elusive; however, recent studies have revealed that there are alterations in endometrial microRNAs (miRs) in women suffering repeated implantation failure and that one of the altered miRs is miR-145. We assessed the role of miR-145 and its target IGF1R, in early implantation. miR-145 overexpression and IGF1R knockdown were achieved in Ishikawa endometrial cells. Quantitative PCR, western blotting and 3'UTR luciferase reporter assays confirmed that IGF1R is a direct target of miR-145 in the endometrium. Attachment of mouse embryos or IGF1-coated beads to endometrial epithelial cells was used to study the effects of altered miR-145 and/or IGF1R expression on early implantation events. miR-145 overexpression or specific reduction of IGF1R impaired attachment in both cases. An IGF1R target protector prevented the miR-145-mediated reduction in IGF1R and reversed the effect of miR-145 overexpression on attachment. The data demonstrate that miR-145 influences embryo attachment by reducing the level of IGF1R in endometrium.