Hypomethylation of the miRNA-34a gene promoter is associated with Severe Preeclampsia

DNA methylation landscape in pregnancy-induced hypertension: progress and challenges

Gestational hypertension (PIH), especially pre-eclampsia (PE), is a common complication of pregnancy. This condition poses significant risks to the health of both the mother and the fetus. Emerging evidence suggests that epigenetic modifications, particularly DNA methylation, may play a role in initiating the earliest pathophysiology of PIH. This article describes the relationship between DNA methylation and placental trophoblast function, genes associated with the placental microenvironment, the placental vascular system, and maternal blood and vascular function, abnormalities of umbilical cord blood and vascular function in the onset and progression of PIH, as well as changes in DNA methylation in the progeny of PIH, in terms of maternal, fetal, and offspring. We also explore the latest research on DNA methylation-based early detection, diagnosis and potential therapeutic strategies for PIH. This will enable the field of DNA methylation research to continue to enhance our understanding of the epigenetic regulation of PIH genes and identify potential therapeutic targets.

miR34a-5p impedes CLOCK expression in chronodisruptive C57BL/6J mice and potentiates pro-atherogenic manifestations

INTRODUCTION

Altered circadian rhythms underlie manifestation of several cardiovascular disorders, however a little is known about the mediating biomolecules. Multiple transcriptional-translational feedback loops control circadian-clockwork wherein; micro RNAs (miRNAs) are known to manifest post transcriptional regulation. This study assesses miR34a-5p as a mediating biomolecule.

METHOD

8-10-week-old male C57BL/6J mice (n = 6/group) were subjected to photoperiodic manipulation induced chronodisruption and thoracic aortae were examined for miRNA, gene (qPCR) and protein (Immunoblot) expression studies. Histomorphological changes were assessed for pro-atherogenic manifestations (fibrillar arrangement, collagen/elastin ratio, intima-media thickening). Computational studies for miRNA-mRNA target prediction were done using TargetScan and miRDB. Correlative in vitro studies were done in serum synchronized HUVEC cells. Time point based studies were done at five time points (ZT 0, 6, 12, 18, 24) in 24h.

RESULTS

Chronodisruption induced hypomethylation in the promoter region of miR34a-5p, in the thoracic aortae, culminating in elevated miRNA titers. In a software-based detection of circadian-clock-associated targets of miR34a-5p, Clock and Sirt1 genes were identified. Moreover, miR34a-5p exhibited antagonist circadian oscillations to that of its target genes CLOCK and SIRT1 in endothelial cells. Luciferase reporter gene assay further showed that miR34a-5p interacts with the 3'UTR of the Clock gene to lower its expression, disturbing the operation of positive arm of circadian clock system. Elevated miR34a-5p and impeded SIRT1 expression in a chronodisruptive aortae exhibited pro-atherogenic changes observed in form of gene expression, increased collagen/elastin ratio, fibrillar derangement and intimal-media thickening.

CONCLUSION

The study reports for the first time chronodisruption mediated miR34a-5p elevation, its circadian expression and interaction with the 3'UTR of Clock gene to impede its expression. Moreover, elevated miR34a-5p and lowered SIRT1 expression in the chronodisruptive aortae lead off cause-consequence relationship of chronodisruption mediated proatherogenic changes.

CORM-A1 Alleviates Pro-Atherogenic Manifestations via miR-34a-5p Downregulation and an Improved Mitochondrial Function

Atherogenesis involves multiple cell types undergoing robust metabolic processes resulting in mitochondrial dysfunction, elevated reactive oxygen species (ROS), and consequent oxidative stress. Carbon monoxide (CO) has been recently explored for its anti-atherogenic potency; however, the effects of CO on ROS generation and mitochondrial dysfunction in atherosclerosis remain unexplored. Herein, we describe the anti-atherogenic efficacy of CORM-A1, a CO donor, in in vitro (ox-LDL-treated HUVEC and MDMs) and in vivo (atherogenic diet-fed SD rats) experimental models. In agreement with previous data, we observed elevated miR-34a-5p levels in all our atherogenic model systems. Administration of CO via CORM-A1 accounted for positive alterations in the expression of miR-34a-5p and transcription factors/inhibitors (P53, NF-κB, ZEB1, SNAI1, and STAT3) and DNA methylation pattern, thereby lowering its countenance in atherogenic milieu. Inhibition of miR-34a-5p expression resulted in restoration of SIRT-1 levels and of mitochondrial biogenesis. CORM-A1 supplementation further accounted for improvement in cellular and mitochondrial antioxidant capacity and subsequent reduction in ROS. Further and most importantly, CORM-A1 restored cellular energetics by improving overall cellular respiration in HUVECs, as evidenced by restored OCR and ECAR rates, whereas a shift from non-mitochondrial to mitochondrial respiration was observed in atherogenic MDMs, evidenced by unaltered glycolytic respiration and maximizing OCR. In agreement with these results, CORM-A1 treatment also accounted for elevated ATP production in both in vivo and in vitro experimental models. Cumulatively, our studies demonstrate for the first time the mechanism of CORM-A1-mediated amelioration of pro-atherogenic manifestations through inhibition of miR-34a-5p expression in the atherogenic milieu and consequential rescue of SIRT1-mediated mitochondrial biogenesis and respiration.

miR-24-3p regulation of retinol binding protein 4 in trophoblast biofunction and preeclampsia

Preeclampsia (PE) is a pregnancy-related disease and is the leading cause of overall maternal mortality and morbidity. Our previous studies have shown that the serum and placental levels of retinol-binding protein 4 (RBP4) in PE are reduced. Our previous bioinformatics analysis predicted that RBP4 is a target of the microRNA miRNA-24-3p. In this study, our database analysis also indicated that RBP4 is a miR-24-3p target. Compared with that of the normal placenta, the expression level of RBP4 in human PE placenta was significantly reduced, and miR-24-3p was highly expressed. In HTR-8/SVneo cells, transfection of exogenous miR-24-3p reduced RBP4 expression. A dual-luciferase reporter assay validated RBP4 as a direct target of miR-24-3p, indicating that it directly binds to the 3'-untranslated region of RBP4. This binding was reversed by a mutation in the microRNA-binding site. Transwell invasion experiments and CCK8 assay showed that inhibitory effect of miR-24-3p reduced RBP4 mediated HTR-8/SVneo cell invasion and proliferation. These data provide a new overarching perspective on the physiological role played by miR-24-3p in regulating RBP4 during trophoblast dysfunction and PE development.

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.

Roles of noncoding RNAs in preeclampsia

Preeclampsia (PE) is an idiopathic disease that occurs during pregnancy. It comprises multiple organ and system damage, and can seriously threaten the safety of the mother and infant throughout the perinatal period. As the pathogenesis of PE is unclear, there are few specific remedies. Currently, the only way to eliminate the clinical symptoms is to terminate the pregnancy. Although noncoding RNA (ncRNA) was once thought to be the "junk" of gene transcription, it is now known to be widely involved in pathological and physiological processes, including pregnancy-related disorders. Moreover, there is growing evidence that the unbalanced expression of specific ncRNA is involved in the pathogenesis of PE. In the present review, we summarize the expression patterns of ncRNAs, i.e., microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), and the functional mechanisms by which they affect the development of PE, and examine the clinical significance of ncRNAs as biomarkers for the diagnosis of PE. We also discuss the contributions made by genetic polymorphisms and epigenetic ncRNA regulation to PE. In the present review, we wish to explore and reinforce the clinical value of ncRNAs as noninvasive biomarkers of PE.

The effects of placental long noncoding RNA H19 polymorphisms and promoter methylation on H19 expression in association with preeclampsia susceptibility

The effect of DNA methylation on gene expression triggered it as a susceptibility factor in various diseases including preeclampsia (PE). The pathogenesis of PE is closely associated with the methylation status and genetic variants of relevant genes. Therefore, the aim of the study was to investigate the possible impacts of the placental DNA methylation and rs3741219, rs217727, and rs2107425 polymorphisms of the H19 gene on the PE susceptibility as well as the its mRNA expression. Moreover, eight haplotypes of three loci in the H19 gene were analyzed. In this case-control study, the placentas of 107 preeclamptic and 113 non-preeclamptic women were collected after delivery. The methylation status was assessed by methylation-specific polymerase chain reaction (PCR). The H19 polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism or amplification refractory mutation system-polymerase chain reaction methods. The quantitative real time PCR was used for mRNA expression assay. The placental H19 rs3741219 and rs2107425 polymorphisms were not associated with PE. However, H19 rs217727CT and TT genotypes might be associated with a 9.2- and 17.7-fold increased risk of PE, respectively. The T_rs3741219 C_rs217727 C_rs2107425 and T_rs3741219 C_rs217727 T_rs2107425 haplotypes were significantly lower, whereas the T_rs3741219 T_rs217727 C_rs2107425 and C_rs3741219 T_rs217727 C_rs2107425 haplotypes were significantly higher in PE women. Promoter but not upstream region hypermethylation of H19 gene could be led to decreased risk of PE (MM vs. UM + UU). No significant difference was observed in the placental mRNA expression between two groups. The H19 expression was significantly higher in women with unmethylated (UU), compared to methylated promoter (MM). The H19 expression was 17- and 15-fold higher in H19-rs2107425 CC and CT genotypes in PE women. In conclusion, the H19 rs2107425 polymorphism was associated with a higher risk of PE and increased H19 mRNA expression. The promoter hypermethylation of H19 gene was associated with a lower risk of PE and decreased H19 mRNA expression.

Analysis of polymorphisms, promoter methylation, and mRNA expression profile of maternal and placental P53 and P21 genes in preeclamptic and normotensive pregnant women

Background

Preeclampsia (PE), as a multisystem disorder, is associated with maternal hypertension and proteinuria. Apoptosis seems to be involved in the pathophysiology of PE, although its precise pathogenic mechanisms are not well established. In this study, we aimed to identify the association between maternal TP53-rs1042522, P21-rs1801270, and P21-rs1059234 polymorphisms and PE. In addition, we examined the effects of promoter methylation and TP53 and P21 polymorphisms on placental mRNA expression in PE women.

Methods

The blood of 226 PE women and 228 normotensive pregnant women was examined in this study. In addition, the placentas were genotyped in 109 PE and 112 control women. The methylation status was assessed by a methylation-specific PCR assay, while mRNA expression was examined via Quantitative Real Time PCR.

Results

The maternal and placental P21-rs1801270 CA genotype had a significant association with the reduced risk of PE. In the dominant, recessive, and allelic models, maternal/placental P21-rs1059234 polymorphism had no statistically significant association with the risk of PE. On the other hand, the reduced risk of PE was associated with maternal, but not placental TP53-rs1042522 polymorphism in the dominant and recessive models. The maternal and placental P21-rs1801270 polymorphism was associated with PE risk. The maternal P21 T_rs1059234C_rs1801270 haplotype was associated with 3.4-fold increase in PE risk, However the maternal P21 T_rs1059234A_{rs 1801270} haplotype and placental C_rs1059234CA _rs1801270 haplotype led to 0.5 and 0.4-fold decrease in PE risk, respectively. PE women showed 5.6 times higher levels of placental mRNA expression of TP53 gene, although it was not associated with rs1042522 polymorphism. The relative placental mRNA expression of P21 gene was 0.2 in PE women. It was also 2.4 times higher in individuals with rs1801270CA genotype than those with AA genotype. The hyper-methylation of P21 and TP53 genes in the promoter region was associated with a 3.4-fold and 3-fold increase in PE risk, respectively. However, no association was found between P21 and TP53 mRNA expression and promoter methylation.

Conclusion

In conclusion, P21-rs1801270 and TP53-rs1042522 polymorphisms were involved in reduced risk of PE. P21-rs1801270 was associated with decreased P21 mRNA expression. The hyper-methylation of P21 and TP53 genes in the promoter region was associated with a higher PE risk.

Epigenetic Biomarkers in Cardiovascular Diseases

Cardiovascular diseases are the number one cause of death worldwide and greatly impact quality of life and medical costs. Enormous effort has been made in research to obtain new tools for efficient and quick diagnosis and predicting the prognosis of these diseases. Discoveries of epigenetic mechanisms have related several pathologies, including cardiovascular diseases, to epigenetic dysregulation. This has implications on disease progression and is the basis for new preventive strategies. Advances in methodology and big data analysis have identified novel mechanisms and targets involved in numerous diseases, allowing more individualized epigenetic maps for personalized diagnosis and treatment. This paves the way for what is called pharmacoepigenetics, which predicts the drug response and develops a tailored therapy based on differences in the epigenetic basis of each patient. Similarly, epigenetic biomarkers have emerged as a promising instrument for the consistent diagnosis and prognosis of cardiovascular diseases. Their good accessibility and feasible methods of detection make them suitable for use in clinical practice. However, multicenter studies with a large sample population are required to determine with certainty which epigenetic biomarkers are reliable for clinical routine. Therefore, this review focuses on current discoveries regarding epigenetic biomarkers and its controversy aiming to improve the diagnosis, prognosis, and therapy in cardiovascular patients.

The effect of GPx-1 rs1050450 and MnSOD rs4880 polymorphisms on PE susceptibility: a case- control study

Preeclampsia (PE) is a serious pregnancy complication whose etiology is not fully understood. However, previous reports have suggested that oxidative stress and genetic variants may contribute to the development of PE. This study aimed to examine the relationship between the Glutathione peroxidase-1(GPx-1) and Manganese Superoxide dismutase (MnSOD) polymorphisms and preeclampsia (PE) risk in Iranian women. Genotyping of the studied women, including 179 preeclamptic cases and 202 controls, for GPx-1 rs1050450 and MnSOD rs4880 polymorphisms was conducted using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Our results showed a 1.7- to 1.6-fold increased risk of PE in the rs1050450 CT and CT + TT (dominant model) genotypes compared to CC genotype (OR = 1.7, 95%CI 1.1-2.7; P = 0.01 and OR = 1.6, 95%CI 1.1-2.4; P = 0.02; respectively). We also found a marked correlation between TC and CC genotypes of MnSOD rs4880 polymorphism and a 1.9- to 2.3-fold increase risk of PE (OR = 1.9, 95%CI 1.2-2.9; P = 0.005 and OR = 2.3, 95%CI 1-5.1; P = 0.04, respectively). The rs4880 MnSOD polymorphism was correlated with increased risk of PE in the allelic and dominant models (OR = 1.8, 95% CI 1.2-2.5, P = 0.002; OR = 1.9, 95%CI 1.3-3, P = 0.002, respectively). High frequency of TC/CC genotype of MnSOD rs4880 and CT genotypes of rs1050450 polymorphism in PE patients compared to controls showed the contribution of these variants to PE susceptibility.