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.

Human leukocyte antigen HLA-C, HLA-G, HLA-F, and HLA-E placental profiles are altered in early severe preeclampsia and preterm birth with chorioamnionitis.

BACKGROUND: The extravillous trophoblast expresses each of the nonclassical major histocompatibility complex class I antigens-human leukocyte antigens E, F, and G-and a single classical class I antigen, human leukocyte antigen C. We recently demonstrated dynamic expression patterns of human leukocyte antigens C, G, and F during early extravillous trophoblast invasion and placentation. OBJECTIVE: This study aimed to investigate the hypothesis that the immune inflammatory mediated complications of pregnancy such as early preeclampsia and preterm labor may show altered expression profiles of nonclassical human leukocyte antigens. STUDY DESIGN: Real-time quantitative polymerase chain reaction, western blot, and immunohistochemistry were performed on placental villous tissues and basal plate sections from term nonlaboring deliveries, preterm deliveries, and severe early-onset preeclampsia, both with and without small-for-gestational-age neonates. RESULTS: Human leukocyte antigen G is strongly and exclusively expressed by the extravillous trophoblast within the placental basal plate, and its levels increase in pregnancies complicated by severe early-onset preeclampsia with small-for-gestational-age neonates relative to those of healthy term controls. Human leukocyte antigen C shows a similar profile in the extravillous trophoblast of preeclamptic pregnancies, but significantly decreases in the villous placenta. Human leukocyte antigen F protein levels are decreased in both extravillous trophoblast and villous placenta of severe early-onset preeclamptic pregnancies, both with and without small-for-gestational-age neonates, compared with those found in term and preterm birth deliveries. Human leukocyte antigen E decreases in blood vessels in placentas from preeclamptic pregnancies relative to its levels in term and preterm birth deliveries. Placental levels of human leukocyte antigens F and C are increased in cases of preterm birth with chorioamnionitis relative to those of cases of idiopathic preterm birth. CONCLUSION: Dysregulation of placental human leukocyte antigen expression at the maternal-fetal interface may contribute to compromised maternal tolerance in preterm birth with chorioamnionitis and excessive maternal systemic inflammation associated with severe early-onset preeclampsia.

Overexpression of miR-210-3p Impairs Extravillous Trophoblast Functions Associated with Uterine Spiral Artery Remodeling.

Hsa-miR-210-3p has been reported to be upregulated in preeclampsia (PE); however, the functions of miR-210-3p in placental development are not fully understood, and, consequently, miR-210-3p's role in the pathogenesis of PE is still under investigation. In this study, we found that overexpression of miR-210-3p reduced trophoblast migration and invasion, extravillous trophoblast (EVT) outgrowth in first trimester explants, expression of endovascular trophoblast (enEVT) markers and the ability of trophoblast to form endothelial-like networks. In addition, miR-210-3p overexpression significantly downregulated the mRNA levels of interleukin-1B and -8, as well as CXC motif ligand 1. These cytokines have been suggested to play a role in EVT invasion and the recruitment of immune cells to the spiral artery remodeling sites. We also showed that caudal-related homeobox transcription factor 2 (CDX2) is targeted by miR-210-3p and that CDX2 downregulation mimicked the observed effects of miR-210-3p upregulation in trophoblasts. These findings suggest that miR-210-3p may play a role in regulating events associated with enEVT functions and its overexpression could impair spiral artery remodeling, thereby contributing to PE.

Overview of MicroRNA Biogenesis, Mechanisms of Actions, and Circulation.

MicroRNAs (miRNAs) are a class of non-coding RNAs that play important roles in regulating gene expression. The majority of miRNAs are transcribed from DNA sequences into primary miRNAs and processed into precursor miRNAs, and finally mature miRNAs. In most cases, miRNAs interact with the 3' untranslated region (3' UTR) of target mRNAs to induce mRNA degradation and translational repression. However, interaction of miRNAs with other regions, including the 5' UTR, coding sequence, and gene promoters, have also been reported. Under certain conditions, miRNAs can also activate translation or regulate transcription. The interaction of miRNAs with their target genes is dynamic and dependent on many factors, such as subcellular location of miRNAs, the abundancy of miRNAs and target mRNAs, and the affinity of miRNA-mRNA interactions. miRNAs can be secreted into extracellular fluids and transported to target cells via vesicles, such as exosomes, or by binding to proteins, including Argonautes. Extracellular miRNAs function as chemical messengers to mediate cell-cell communication. In this review, we provide an update on canonical and non-canonical miRNA biogenesis pathways and various mechanisms underlying miRNA-mediated gene regulations. We also summarize the current knowledge of the dynamics of miRNA action and of the secretion, transfer, and uptake of extracellular miRNAs.

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.

Accurate MicroRNA Analysis in Crude Cell Lysate by Capillary Electrophoresis-Based Hybridization Assay in Comparison with Quantitative Reverse Transcription-Polymerase Chain Reaction.

Accurate quantitation of microRNA (miRNA) in tissue samples is required for validation and clinical use of miRNA-based disease biomarkers. Since sample processing, such as RNA extraction, introduces undesirable biases, it is advantageous to measure miRNA in a crude cell lysate. Here, we report on accurate miRNA quantitation in crude cell lysate by a CE-based hybridization assay termed direct quantitative analysis of multiple miRNAs (DQAMmiR). Accuracy and precision of miRNA quantitation were determined for miRNA samples in a crude cell lysate, RNA extract from the lysate, and a pure buffer. The results showed that the measurements were matrix-independent with inaccuracies of below 13% from true values and relative standard deviations of below 11% from the mean values in a miRNA concentration range of 2 orders of magnitude. We compared DQAMmiR-derived results with those obtained by a benchmark miRNA-quantitation method-quantitative reverse transcription-polymerase chain reaction (qRT-PCR). qRT-PCR-based measurements revealed multifold inaccuracies and relative standard deviations of up to 70% in crude cell lysate. Robustness of DQAMmiR to changes in sample matrix makes it a perfect candidate for validation and clinical use of miRNA-based disease biomarkers.

Automated Quantification and Analysis of Cell Counting Procedures Using ImageJ Plugins.

The National Institute of Health's ImageJ is a powerful, freely available image processing software suite. ImageJ has comprehensive particle analysis algorithms which can be used effectively to count various biological particles. When counting large numbers of cell samples, the hemocytometer presents a bottleneck with regards to time. Likewise, counting membranes from migration/invasion assays with the ImageJ plugin Cell Counter, although accurate, is exceptionally labor intensive, subjective, and infamous for causing wrist pain. To address this need, we developed two plugins within ImageJ for the sole task of automated hemocytometer (or known volume) and migration/invasion cell counting. Both plugins rely on the ability to acquire high quality micrographs with minimal background. They are easy to use and optimized for quick counting and analysis of large sample sizes with built-in analysis tools to help calibration of counts. By combining the core principles of Cell Counter with an automated counting algorithm and post-counting analysis, this greatly increases the ease with which migration assays can be processed without any loss of accuracy.

MicroRNAs in Human Placental Development and Pregnancy Complications.

MicroRNAs (miRNAs) are small non-coding RNAs, which function as critical posttranscriptional regulators of gene expression by promoting mRNA degradation and translational inhibition. Placenta expresses many ubiquitous as well as specific miRNAs. These miRNAs regulate trophoblast cell differentiation, proliferation, apoptosis, invasion/migration, and angiogenesis, suggesting that miRNAs play important roles during placental development. Aberrant miRNAs expression has been linked to pregnancy complications, such as preeclampsia. Recent research of placental miRNAs focuses on identifying placental miRNA species, examining differential expression of miRNAs between placentas from normal and compromised pregnancies, and uncovering the function of miRNAs in the placenta. More studies are required to further understand the functional significance of miRNAs in placental development and to explore the possibility of using miRNAs as biomarkers and therapeutic targets for pregnancy-related disorders. In this paper, we reviewed the current knowledge about the expression and function of miRNAs in placental development, and propose future directions for miRNA studies.