Circular RNA hsa_circ_0000848 Promotes Trophoblast Cell Migration and Invasion and Inhibits Cell Apoptosis by Sponging hsa-miR-6768-5p

Circular RNA hsa_circ_0081343 modulates trophoblast autophagy through Rbm8a nuclear translocation

INTRODUCTION

Fetal growth restriction (FGR) is a kind of obstetric complication that seriously endangers fetal life. Recent studies reported significant reduction of hsa_circ_0081343 in human placenta developed in FGR and is involved in cell migration, invasion, and apoptosis of trophoblast by acting as microRNA sponges. Autophagy is required for invasion of trophoblast cells and for vascular remodeling during placentation. In this study, we aimed to explore the mechanistic link between hsa_circ_0081343 and autophagy.

METHODS

We investigated the interactions between hsa_circ_0081343 and RNA-binding proteins were studied by RNA pull-down assay, mass spectrometry and RNA immunoprecipitation assay. The mechanism of nuclear translocation of Rbm8a were assessed by reverse transcription-quantitative PCR, Western blot, immunofluorescence and Co-Immunoprecipitation. Western blot, immunofluorescence and transmission electron microscopy were performed to elucidate the mechanism underlying hsa_circ_0081343 and/or Rbm8a mediated regulation of autophagy.

RESULTS

hsa_circ_0081343 served as an RNA-binding protein (RBP) sponge. RNA binding motif protein 8A (Rbm8a) was directly bound to hsa_circ_0081343 in the cytoplasm, while knockdown of hsa_circ_0081343 facilitated Rbm8a localization in the nucleus. We also identified Rbm8a as a potential import cargo for Importin13 (Ipo13), which transported Rbm8a across the nuclear membrane into the nucleus. Ipo13 recognized Rbm8a via a functional nuclear localization signal (NLS). Furthermore, the mechanistic study revealed that hsa_circ_0081343-mediated nuclear translocation of Rbm8a activated trophoblast autophagy.

DISCUSSION

Our results suggest that hsa_circ_0081343 could bind to RBP and the interaction between hsa_circ_0081343 and Rbm8a participate in regulating autophagy. These findings offer novel molecular targets and insights for a potential therapeutic strategy against FGR.

CircCUL1 inhibits trophoblast cell migration and invasion and promotes cell autophagy by sponging hsa-miR-30e-3p in fetal growth restriction via the ANXA1/PI3K/AKT axis

Fetal growth restriction (FGR) severely affects the health outcome of newborns and represents a major cause of perinatal morbidity. The precise involvement of circCULT1 in the progression of FGR remains unclear. We performed next-generation sequencing and RT-qPCR to identify differentially expressed circRNAs in placental tissues affected by FGR by comparing them with unaffected counterparts. Edu, flow cytometry, and transwell assay were conducted to detect HTR8/SVneo cell's function in regard to cell proliferation, migration, and invasion. The interaction between circCUL1 and hsa-miR-30e-3p was assessed through dual-luciferase reporter assays, validation of the interaction between circCUL1 and ANXA1 was performed using RNA pulldown and immunoprecipitation assays. Western blot analysis was performed to evaluate protein levels of autophagy markers and components of the PI3K/AKT signaling pathway. A knockout (KO) mouse model was established for homologous mmu-circ-0001469 to assess fetal mouse growth and development indicators. Our findings revealed an upregulation of circCUL1 expression in placental tissues from patients with FGR. We found that suppression of circCUL1 increased the trophoblast cell proliferation, migration, and invasion, circCUL1 could interact with hsa-miR-30e-3p. Further, circCUL1 stimulated autophagy, modulating trophoblast cell autophagy via the ANXA1/PI3K/AKT pathway, and a notable disparity was observed, with KO mice displaying accelerated embryo development and exhibiting heavier placentas in comparison to wild-type C57BL/6 mice. By modulating the ANXA1/PI3K/AKT signaling pathway through the interaction with hsa-miR-30e-3p, circCUL1 promotes autophagy while concurrently suppressing trophoblast cell proliferation, migration, and invasion. These findings offer novel insights into potential diagnostic markers and therapeutic targets for FGR research.

CircTHBS1 promotes trophoblast cell migration and invasion and inhibits trophoblast apoptosis by regulating miR-136-3p/IGF2R axis

The precise molecular mechanism behind fetal growth restriction (FGR) is still unclear, although there is a strong connection between placental dysfunction, inadequate trophoblast invasion, and its etiology and pathogenesis. As a new type of non-coding RNA, circRNA has been shown to play a crucial role in the development of FGR. This investigation identified the downregulation of hsa_circ_0034533 (circTHBS1) in FGR placentas through high-sequencing analysis and confirmed this finding in 25 clinical placenta samples using qRT-PCR. Subsequent in vitro functional assays demonstrated that silencing circTHBS1 inhibited trophoblast proliferation, migration, invasion, and epithelial mesenchymal transition (EMT) progression and promoted apoptosis. Furthermore, when circTHBS1 was overexpressed, cell function experiments showed the opposite result. Analysis using fluorescence in situ hybridization revealed that circTHBS1 was primarily found in the cytoplasmic region. Through bioinformatics analysis, we anticipated the involvement of miR-136-3p and IGF2R in downstream processes, which was subsequently validated through qRT-PCR and dual-luciferase assays. Moreover, the inhibition of miR-136-3p or the overexpression of IGF2R partially reinstated proliferation, migration, and invasion abilities following the silencing of circTHBS1. In summary, the circTHBS1/miR-136-3p/IGF2R axis plays a crucial role in the progression and development of FGR, offering potential avenues for the exploration of biological indicators and treatment targets.

circAMN1-Mediated Ferroptosis Regulates the Expulsion of Placenta in Trophoblast Cells

After delivery, the death of trophoblast cells can promote the expulsion of the placenta. Ferroptosis, an iron-dependent programmed cell death, is involved in mammalian development. Circular RNAs are associated with placental development; however, it is unclear whether circular RNAs regulate the expulsion of fetal membranes through ferroptosis. The gene expression profiles in the tail vein blood of Holstein cows with normal and retained placentas were investigated using RNA sequencing and a GSE214588 dataset. circAMN1 and SLC39A8 expression was significantly downregulated in the blood of cows with a retained placenta, whereas miR-205_R-1 expression was significantly upregulated. We validated erastin-induced ferroptosis in trophoblast cells. Transfection with si-circAMN1 and miR-205_R-1 mimic reduced intracellular total iron, Fe2+, and glutathione disulfide levels; increased intracellular glutathione levels and glutathione/glutathione disulfide; and enhanced cell viability in these cells. In contrast, transfection with pcDNA3.1 circAMN1 and an miR-205_R-1 inhibitor promoted ferroptosis. As an miR-205_R-1 sponge, circAMN1 regulated the expression of SLC39A8 to control erastin-induced ferroptosis and regulated the proliferation, invasion, and migration of trophoblast cells. Our findings provide a theoretical basis for studying the mechanism by which programmed cell death regulates fetal membrane expulsion and indicate its potential as a therapeutic target for placenta retention.

Unraveling the molecular mechanisms driving enhanced invasion capability of extravillous trophoblast cells: a comprehensive review

Precise extravillous trophoblast (EVT) invasion is crucial for successful placentation and pregnancy. This review focuses on elucidating the mechanisms that promote heightened EVT invasion. We comprehensively summarize the pivotal roles of hormones, angiogenesis, hypoxia, stress, the extracellular matrix microenvironment, epithelial-to-mesenchymal transition (EMT), immunity, inflammation, programmed cell death, epigenetic modifications, and microbiota in facilitating EVT invasion. The molecular mechanisms underlying enhanced EVT invasion may provide valuable insights into potential pathogenic mechanisms associated with diseases characterized by excessive invasion, such as the placenta accreta spectrum (PAS), thereby offering novel perspectives for managing pregnancy complications related to deficient EVT invasion.

The role of circular RNA in preeclampsia: From pathophysiological mechanism to clinical application

Preeclampsia (PE) is a common pregnancy-induced hypertension disorder that poses a significant threat to the health of pregnant women and fetuses, and has become a leading cause of maternal, fetal, and neonatal mortality. Currently, the therapy strategy for PE is mainly prevention management and symptomatic treatment, and only delivery can completely terminate PE. Therefore, a deeper understanding of the pathogenesis of PE is needed to make treatment and prevention more effective and targeted. With the deepening of molecular etiology research, circular RNAs (circRNAs) have been found to be widely involved in various processes of PE pathogenesis. As a kind of RNA with a special "head to tail" loop structure, the characteristics of circRNAs enable them to play diverse roles in the pathophysiology of PE, and can also serve as ideal biomarkers for early prediction and monitoring progression of PE. In this review, we summarized the latest research on PE-related circRNAs, trying to elucidate the unique or shared roles of circRNAs in various pathophysiological mechanisms of PE, aiming to provide a whole picture of current research on PE-related circRNAs, and extend a new perspective for the precise screening and targeted therapy of PE.

Research progress in the role of non-coding RNAs and embryo implantation

Non-coding RNA (ncRNA) refers to RNA that lack the ability to encode protein. Based on their distinct biological characteristics, ncRNA are mainly classified into microRNA (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA). NcRNA plays a crucial regulatory role in various biological processes. Pregnancy is a highly intricate physiological process that requires successful completion of multiple steps. Embryo implantation, as a key event of pregnancy, which is regulated by numerous factors, including embryo development, endometrial changes, and the maternal-embryo crosstalk. A diverse array of regulatory mechanisms ensures the accomplishment of embryo localization, adhesion, invasion, and ultimately successful implantation. MiRNA, lncRNA, and circRNA are extensively studied ncRNA molecules at present, which play an important role in the physiological and pathological processes associated with embryo implantation through targeting and regulating the expression of multiple cytokine and genes. With advancements in molecular biology technology, it is anticipated that ncRNA will contribute to the prediction and enhancement of clinical pregnancy outcomes from a molecular perspective.

Emerging role of miRNAs, lncRNAs, and circRNAs in pregnancy-associated diseases

ABSTRACT

Accumulating studies have demonstrated that non-coding RNAs (ncRNAs), functioning as important regulators of transcription and translation, are involved in the establishment and maintenance of pregnancy, especially the maternal immune adaptation process. The endometrial stromal cells (ESCs), trophoblast cells, and decidua immune cells that reside at the maternal-fetal interface are thought to play significant roles in normal pregnancy and pregnancy-associated diseases. Here, we reviewed the up-to-date evidence on how microRNA, long non-coding RNA, and circular RNA regulate ESCs, trophoblast cells, and immune cells and discussed the potential applications of these ncRNAs as diagnostic and therapeutic markers in pregnancy complications.

Circ_0001326 suppresses trophoblast cell proliferation, invasion, migration and epithelial-mesenchymal transition progression in preeclampsia by miR-188-3p/HtrA serine peptidase 1 axis

BACKGROUND

It has been reported that the alteration of circular RNAs (circRNAs) during preeclampsia (PE) can be associated with the pathogenesis of this disease. Herein, this work investigated the potential functions and mechanism of circ_0001326 in PE process.

METHODS

The levels of genes and proteins were evaluated by quantitative real-time PCR (qRT-PCR) and western blotting. The functional experiments were conducted using cell counting kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, transwell, and wound healing assays, respectively. The binding between miR-188-3p and circ_0001326 or HtrA serine peptidase 1 (HTRA1) was verified by bioinformatics analysis and dual-luciferase reporter assays.

RESULTS

Circ_0001326 and HTRA1 expression was increased, while miR-188-3p expression was decreased in the placental tissues of preeclamptic singleton pregnant women compared with the normal pregnant women. Functionally, up-regulation of circ_0001326 or HTRA1, or down-regulation of miR-188-3p led to the arrest of cell growth, invasion, migration and epithelial-mesenchymal transition (EMT) process in trophoblast cells. Mechanistically, circ_0001326 acted as a sponge for miR-188-3p, which directly targeted HTRA1. Moreover, circ_0001326 could regulate HTRA1 through sequestering miR-188-3p. A series of rescue experiments showed that miR-188-3p reversed the inhibitory effects of circ_0001326 knockdown on above behaviors of trophoblast cells. Besides that, HTRA1 silencing attenuated the action of miR-188-3p inhibitor on trophoblast cell phenotype alteration.

CONCLUSION

Our study demonstrated that circ_0001326 could promote trophoblast cell proliferation, invasion, migration and EMT in PE by miR-188-3p/HTRA1 axis, indicating a novel insight into the pathogenesis of PE.

Circular RNA hsa-circ-0005238 enhances trophoblast migration, invasion and suppresses apoptosis via the miR-370-3p/CDC25B axis

Background

Fetal growth restriction (FGR) is attributed to various maternal, fetal, and placental factors. Trophoblasts participate in the establishment and maintenance of pregnancy from implantation and placentation to providing nutrition to fetus. Studies have reported that impaired trophoblast invasion and proliferation are among factors driving development of FGR. Circular RNAs (circRNAs) can regulate trophoblast function. We assessed the significance of circRNAs underlying FGR development.

Materials and methods

Next generation sequencing (NGS) was carried out to quantify levels of circRNAs in placenta tissues with and without FGR. In vitro experiments including transfection, (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2Htetrazolium) (MTS) assays, flow cytometry analyses, Transwell assays, wound healing assays, western blotting, qRT-PCR, dual-luciferase assays, immunofluorescence staining, and RIP assay were performed.

Results

There were 18 differentially expressed circRNAs between FGR placentas and uncomplicated pregnancies, while levels of hsa-circ-0005238 were markedly low in FGR placentas. Our in vitro experiments further revealed that hsa-circ-0005238 suppressed apoptosis and enhanced proliferation, migration, invasion of trophoblast cell lines. The hsa-miR-370-3p was identified as a direct target of hsa-circ-0005238. Mechanistically, hsa-miR-370-3p prevents invasion as well as migration of trophoblast cells by downregulating CDC25B.

Conclusion

The hsa-circ-0005238 modulates FGR pathogenesis by inhibiting trophoblast cell invasion and migration through sponging hsa-miR-370-3p. Hence, targeting this circRNA may be an attractive strategy for FGR treatment.

The Placental Epigenome as a Molecular Link Between Prenatal Exposures and Fetal Health Outcomes Through the DOHaD Hypothesis

PURPOSE OF REVIEW

The developmental origins of health and disease (DOHaD) hypothesis posits that the perinatal environment can impact fetal and later life health. The placenta is uniquely situated to assess prenatal exposures in the context of DOHaD because it is an essential ephemeral fetal organ that manages the transport of oxygen, nutrients, waste, and endocrine signals between the mother and fetus. The purpose of this review is to summarize recent studies that evaluated the DOHaD hypothesis in human placentas using epigenomics, including DNA methylation and transcriptomic studies of mRNA, lncRNA, and microRNAs.

RECENT FINDINGS

Between 2016 and 2021, 28 articles evaluated associations between prenatal exposures and placental epigenomics across broad exposure categories including maternal smoking, psychosocial stressors, chemicals, air pollution, and metals. Sixteen of these studies connected exposures to health outcome such as birth weight, fetal growth, or infant neurobehavior through mediation analysis, identification of shared associations between exposure and outcome, or network analysis. These aspects of infant and childhood health serve as a foundation for future studies that aim to use placental epigenetics to understand relationships between the prenatal environment and perinatal complications (such as preterm birth or fetal growth restriction) or later life childhood health. Placental DNA methylation and RNA expression have been linked to numerous prenatal exposures, such as PM2.5 air pollution, metals, and maternal smoking, as well as infant and childhood health outcomes, including fetal growth and birth weight. Placental epigenomics provides a unique opportunity to expand the DOHaD premise, particularly if research applies novel methodologies such as multi-omics analysis, sequencing of non-coding RNAs, mixtures analysis, and assessment of health outcomes beyond early childhood.

Compartmentalized regulation of NAD+ by Di (2-ethyl-hexyl) phthalate induces DNA damage in placental trophoblast

Di (2-ethyl-hexyl) phthalate (DEHP) is a wildly used plasticizer. Maternal exposure to DEHP during pregnancy blocks the placental cell cycle at the G2/M phase by reducing the efficiency of the DNA repair pathways and affects the health of offsprings. However, the mechanism by which DEHP inhibits the repair of DNA damage remains unclear. In this study, we demonstrated that DEHP inhibits DNA damage repair by reducing the activity of the DNA repair factor recruitment molecule PARP1. NAD+ and ATP are two substrates necessary for PARP1 activity. DEHP abated NAD+ in the nucleus by reducing the level of NAD+ synthase NMNAT1 and elevated NAD+ in the mitochondrial by promoting synthesis. Furthermore, DEHP destroyed the mitochondrial respiratory chain, affected the structure and quantity of mitochondria, and decreased ATP production. Therefore, DEHP inhibits PARP1 activity by reducing the amount of NAD+ and ATP, which hinders the DNA damage repair pathways. The supplement of NAD+ precursor NAM can partially rescue the DNA and mitochondria damage. It provides a new idea for the prevention of health problems of offsprings caused by DEHP injury to the placenta.

Regulatory roles of non-coding RNAs and m6A modification in trophoblast functions and the occurrence of its related adverse pregnancy outcomes

Adverse pregnancy outcomes, such as preeclampsia, gestational diabetes mellitus, fetal growth restriction, and recurrent miscarriage, occur frequently in pregnant women and might further induce morbidity and mortality for both mother and fetus. Increasing studies have shown that dysfunctions of human trophoblast are related to these adverse pregnancy outcomes. Recent studies also showed that environmental toxicants could induce trophoblast dysfunctions. Moreover, non-coding RNAs (ncRNAs) have been reported to play important regulatory roles in various cellular processes. However, the roles of ncRNAs in the regulation of trophoblast dysfunctions and the occurrence of adverse pregnancy outcomes still need to be further investigated, especially with exposure to environmental toxicants. In this review, we analyzed the regulatory mechanisms of ncRNAs and m6A methylation modification in the dysfunctions of trophoblast cells and the occurrence of adverse pregnancy outcomes and also summarized the harmful effects of environmental toxicants. In addition to DNA replication, mRNA transcription, and protein translation, ncRNAs and m6A modification might be considered as the fourth and fifth elements that regulate the genetic central dogma, respectively. Environmental toxicants might also affect these processes. In this review, we expect to provide a deeper scientific understanding of the occurrence of adverse pregnancy outcomes and to discover potential biomarkers for the diagnosis and treatment of these outcomes.

The Role of Non-Coding RNAs in the Human Placenta

Non-coding RNAs (ncRNAs) play a central and regulatory role in almost all cells, organs, and species, which has been broadly recognized since the human ENCODE project and several other genome projects. Nevertheless, a small fraction of ncRNAs have been identified, and in the placenta they have been investigated very marginally. To date, most examples of ncRNAs which have been identified to be specific for fetal tissues, including placenta, are members of the group of microRNAs (miRNAs). Due to their quantity, it can be expected that the fairly larger group of other ncRNAs exerts far stronger effects than miRNAs. The syncytiotrophoblast of fetal origin forms the interface between fetus and mother, and releases permanently extracellular vesicles (EVs) into the maternal circulation which contain fetal proteins and RNA, including ncRNA, for communication with neighboring and distant maternal cells. Disorders of ncRNA in placental tissue, especially in trophoblast cells, and in EVs seem to be involved in pregnancy disorders, potentially as a cause or consequence. This review summarizes the current knowledge on placental ncRNA, their transport in EVs, and their involvement and pregnancy pathologies, as well as their potential for novel diagnostic tools.

CircRNA75 and CircRNA72 Function as the Sponge of MicroRNA-200 to Suppress Coelomocyte Apoptosis Via Targeting Tollip in Apostichopus japonicus

Circular RNAs (circRNAs) act as essential regulators in many biological processes, especially in mammalian immune response. Nonetheless, the functions and mechanisms of circRNAs in the invertebrate immune system are largely unclarified. In our previous work, 261 differentially expressed circRNAs potentially related to the development of Apostichopus japonicus skin ulceration syndrome (SUS), which is a major problem restricting the sea cucumber breeding industry, were identified by genome-wide screening. In this study, via miRanda analysis, both circRNA75 and circrRNA72 were shown to share the miR-200 binding site, a key microRNA in the SUS. The two circRNAs were verified to be increased significantly in LPS-exposed primary coelomocytes, similar to the results of circRNA-seq in sea cucumber under Vibrio splendidus-challenged conditions. A dual-luciferase assay indicated that both circRNA75 and circRNA72 could bind miR-200 in vivo, in which circRNA75 had four binding sites of miR-200 and only one for circRNA72. Furthermore, we found that miR-200 could bind the 3’-UTR of Toll interacting protein (Tollip) to negatively mediate the expression of Tollip. Silencing Tollip increased primary coelomocyte apoptosis. Consistently, inference of circRNA75 and circRNA72 could also downregulate Tollip expression, thereby increasing the apoptosis of primary coelomocytes, which could be blocked by miR-200 inhibitor treatment. Moreover, the rate of si-circRNA75-downregulated Tollip expression was higher than that of si-circRNA72 under an equivalent amount. CircRNA75 and circRNA72 suppressed coelomocyte apoptosis by sponging miR-200 to promote Tollip expression. The ability of circRNA to adsorb miRNA might be positively related to the number of binding sites for miRNA.

Circular RNA hsa_circ_0081343 promotes trophoblast cell migration and invasion and inhibits trophoblast apoptosis by regulating miR-210-5p/DLX3 axis

BACKGROUND

Various circular RNAs (circRNAs) are dysregulated in the placenta of fetal growth restriction (FGR) fetuses, but their roles and regulatory mechanisms have not been fully elucidated. Herein, we aimed to elucidate the role of hsa_circ_0081343 in regulating the migration, invasion, and apoptosis of human extravillous trophoblast HTR-8 cells.

METHODS

CircRNA and miRNA levels were examined by quantitative reverse transcription PCR (qRT-PCR). Overexpression plasmid constructs and siRNAs were used to overexpress and knockdown hsa_circ_0081343, respectively. Transwell assays and flow cytometry analyses were performed to evaluate the effects of hsa_circ_0081343 or miR-210-5p on migration, invasion, and apoptosis. Protein levels were analyzed by western blotting. Dual luciferase activity and anti-AGO2 RNA immunoprecipitation (RIP) assays were performed to identify the relationship between miR-210-5p and hsa_circ_0081343.

RESULTS

Hsa_circ_0081343 expression was significantly downregulated in 37 FGR placental tissues compared to healthy placental control tissues. Hsa_circ_0081343 overexpression may inhibit apoptosis by downregulating the expression of cleaved caspase 3 and caspase 9 and alleviating the migration and invasion of HTR-8 cells by inducing the expression of MMP2 and MMP9. The dual luciferase activity and anti-AGO2 RIP assay results showed that hsa_circ_0081343 binds to miR-210-5p. miR-210-5p overexpression eliminated the effect of hsa_circ_0081343 overexpression in HTR-8 cells. Finally, DLX3 was identified as a direct target of miR-210-5p.

CONCLUSIONS

hsa_circ_0081343 expression levels are significantly downregulated in FGR placental tissues. Hsa_circ_0081343 regulates the migration, invasion, and apoptosis of HTR-8 cells via the hsa-miR-210-5p/DLX3 axis.

Circ-PNPT1 contributes to gestational diabetes mellitus (GDM) by regulating the function of trophoblast cells through miR-889-3p/PAK1 axis

BACKGROUND

Gestational diabetes mellitus (GDM) is the most common medical complication of pregnancy. CircRNA polyribonucleotide nucleotidyltransferase 1 (circ-PNPT1) has been found to be abnormally expressed in GDM patients. However, function and mechanism of circ-PNPT1 in GDM remain largely undefined.

METHODS

Levels of circ-PNPT1, microRNA (miR)-889-3p and PAK1 (p21 (RAC1) activated kinase 1) were detected using quantitative real-time polymerase chain reaction and Western blot assays. Cell viability, apoptosis, migration and invasion were determined using cell counting kit-8 assay, flow cytometry, transwell and wound healing assays, respectively. The binding interaction between miR-889-3p and circ-PNPT1 or PAK1 was verified using dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays. Exosomes were obtained from culture media by the use of commercial kits and qualified by transmission electron microscopy (TEM).

RESULTS

Circ-PNPT1 was highly expressed in the placental tissues of GDM and high glucose (HG)-induced trophoblast cells. Knockdown of circ-PNPT1 reversed HG-induced arrest of trophoblast cell viability, migration, invasion and the promotion of cell apoptosis. Mechanistically, we confirmed circ-PNPT1 could promote the expression of PAK1, the target of miR-889-3p, by directly sponging miR-889-3p, and circ-PNPT1 regulated HG-induced trophoblast cell dysfunction by miR-889-3p/PAK1 axis. Further studies showed circ-PNPT1 was packaged into exosomes and could be internalized by surrounding trophoblast cells.

CONCLUSION

Circ-PNPT1 promoted HG-induced trophoblast cell biological dysfunction through miR-889-3p/PAK1 axis. Meanwhile, it could be transferred from HG-induced trophoblast cells to surrounding untreated cells via exosomes.

Circ_0015382 is associated with preeclampsia and regulates biological behaviors of trophoblast cells through miR-149-5p/TFPI2 axis

INTRODUCTION

Circ_0015382 expression was found to be up-regulated in preeclampsia (PE) placenta tissues, while the role and molecular mechanisms of circ_0015382 in PE remain unclear.

METHODS

The expression of circ_0015382, microRNA (miR)-149-5p, and tissue factor pathway inhibitor 2 (TFPI2) was measured using quantitative real-time polymerase chain reaction and Western blot. Cell proliferation, migration, invasion, apoptosis, and cell cycle, were detected using cell counting kit-8, transwell, and flow cytometry assays, respectively. The direct interaction between miR-149-5p and circ_0015382 or TFPI2 was analyzed using the dual-luciferase reporter assay.

RESULTS

Circ_0015382 was highly expressed in placental tissues of PE. Overexpression of circ_0015382 suppressed trophoblast cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT), but induced apoptosis and cell cycle progression, while circ_0015382 knockdown showed inverse effects. MiR-149-5p was confirmed to be a target of circ_0015382, and silencing miR-149-5p reversed the regulatory effects of circ_0015382 knockdown on trophoblast cell biological behaviors. MiR-149-5P was expressed at lower levels in placental tissues of PE, while the expression of its target TFPI2 was higher. Importantly, circ_0015382 could regulate TFPI2 expression via miR-149-5p. Additionally, miR-149-5p was shown to promote trophoblast cell growth, migration, invasion and EMT through TFPI2.

DISCUSSION

Circ_0015382 was associated with the onset and development of PE through suppressing trophoblast cell growth, migration, invasion and EMT via miR-149-5p/TFPI2 axis, revealing a new insight into the pathogenesis of PE and a potential therapeutic target for PE treatment.

Circular RNA CircCOL5A1 Sponges the MiR-7-5p/Epac1 Axis to Promote the Progression of Keloids Through Regulating PI3K/Akt Signaling Pathway

Keloids, as a result of abnormal wound healing in susceptible individuals, are characterized by the hyper-proliferation of fibroblasts and exaggerated deposition of extracellular matrix. Current surgical and therapeutic modalities provide limited satisfactory results. Growing evidence has highlighted the roles of circRNAs in acting as miRNA sponges. However, up to date, the regulatory mechanism of circRNAs in the pathological process of keloids has rarely been reported. In this study, cell proliferation, cell migration, flow cytometry, western blotting, fluorescence in situ hybridization, dual-luciferase activity, and immunohistochemistry assays were applied to explore the roles and mechanisms of the circCOL5A1/miR-7-5p/Epac1 axis in the keloid. The therapeutic potential of circCOL5A1 was investigated by establishing keloid implantation models. The RT-qPCR result revealed that circCOL5A1 expression was obviously higher in keloid tissues and keloid fibroblasts. Subsequent cellular experiments demonstrated that circCOL5A1 knockdown repressed the proliferation, migration, extracellular matrix (ECM) deposition, whereas promoted cell apoptosis, through the PI3K/Akt signaling pathway. Furthermore, RNA-fluorescence in situ hybridization (RNA-FISH) illustrated that both circCOL5A1 and miR-7-5p were located in the cytoplasm. The luciferase reporter gene assay confirmed that exact binding sites were present between circCOL5A1 and miR-7-5p, as well as between miR-7-5p and Epac1. Collectively, the present study revealed that circCOL5A1 functioned as competing endogenous RNA (ceRNA) by adsorbing miR-7-5p to release Epac1, which contributed to pathological hyperplasia of keloids through activating the PI3K/Akt signaling pathway. Our data indicated that circCOL5A1 might serve as a novel promising therapeutic target and represent a new avenue to understand underlying pathogenesis for keloids.

CircAMOTL1 Promotes Tumorigenesis Through miR-526b/SIK2 Axis in Cervical Cancer

Background

Cervical cancer is one of the most common malignancies in women, leading to major health problems for its high morbidity and mortality. Numerous studies have demonstrated that circular RNAs (circRNAs) could be participated in the progression of multifarious diseases, especially plentiful carcinomas. CircAMOTL1 (angiomotin-like1, ID: hsa_circ_0004214), which is located on human chromosome 11:9 4532555-94533477, is involved in the occurrence of breast cancer, etc. However, the intrinsic and concrete molecular mechanism of circAMOTL1 in cervical carcinomas remained thoroughly unclear, which was also the bottleneck of circRNAs studies in cancer.

Methods

The relative expression levels of circAMOTL1 and miR-526b in cervical carcinoma patients’ specimens and cervical carcinoma cell lines were detected by RT-qPCR. Through experiments including loss-function and overexpression, the biological effects of circAMOTL1 and miR-526b on the proliferation, migration, apoptosis, and tumorigenicity were explored in cervical carcinomas. Dual luciferase reporter gene analysis, western blot, and other methods were adopted to explore the circAMOTL1 potential mechanism in cervical carcinomas.

Results

In our experiments, our researches displayed that circAMOTL1 was significantly higher expression in cervical carcinomas specimens and cell lines. Further experiments illustrated that the knockdown of circAMOTL1 could restrain the malignant phenotype, AKT signaling, and epithelial–mesenchymal transition (EMT) of in cervical carcinomas cells. Meanwhile miR-526b was downregulated in cervical carcinomas and even miR-526b could partially reverse circAMOTL1 function in malignant cervical tumor cells. CircAMOTL1 acts as a microRNA (miRNA) sponge that actively regulates the expression of salt-inducible kinase 2 (SIK2) to sponge miR-526b and subsequently increases malignant phenotypes of cervical carcinomas cells. In a word, circAMOTL1 acts a carcinogenic role and miR-526b serves as the opposite function of antioncogene in the cervical carcinoma pathogenesis.

Conclusion

CircAMOTL1-miR-526b-SIK2 axis referred to the malignant progression and development of cervical carcinomas. CircAMOTL1 expression was inversely correlated with miR-526b and positively correlated with SIK2 mRNA in cervical cancer tissues. Thus, circAMOTL1 exerted an oncogenic role in cervical cancer progression through sponging miR-526b. Taken together, our study revealed that circAMOTL1 acted as an oncogene and probably was a potential therapeutic target for the cervical cancer.