Gestational Diabetes Mellitus Impairs Fetal Endothelial Cell Functions Through a Mechanism Involving MicroRNA-101 and Histone Methyltransferase Enhancer of Zester Homolog-2

Abstract

Objective— Gestational diabetes mellitus (GDM) produces fetal hyperglycemia with increased lifelong risks for the exposed offspring of cardiovascular and other diseases. Epigenetic mechanisms induce long-term gene expression changes in response to in utero environmental perturbations. Moreover, microRNAs (miRs) control the function of endothelial cells (ECs) under physiological and pathological conditions and can target the epigenetic machinery. We investigated the functional and expressional effect of GDM on human fetal ECs of the umbilical cord vein (HUVECs). We focused on miR-101 and 1 of its targets, enhancer of zester homolog-2 (EZH2), which trimethylates the lysine 27 of histone 3, thus repressing gene transcription. EZH2 exists as isoforms α and β. Approach and Results— HUVECs were prepared from GDM or healthy pregnancies and tested in apoptosis, migration, and Matrigel assays. GDM-HUVECs demonstrated decreased functional capacities, increased miR-101 expression, and reduced EZH2- β and trimethylation of histone H3 on lysine 27 levels. MiR-101 inhibition increased EZH2 expression and improved GDM-HUVEC function. Healthy HUVECs were exposed to high or normal d -glucose concentration for 48 hours and then tested for miR-101 and EZH2 expression. Similar to GDM, high glucose increased miR-101 expression. Chromatin immunoprecipitation using an antibody for EZH2 followed by polymerase chain reaction analyses for miR-101 gene promoter regions showed that both GDM and high glucose concentration reduced EZH2 binding to the miR-101 locus in HUVECs. Moreover, EZH2-β overexpression inhibited miR-101 promoter activity in HUVECs. Conclusions— GDM impairs HUVEC function via miR-101 upregulation. EZH2 is both a transcriptional inhibitor and a target gene of miR-101 in HUVECs, and it contributes to some of the miR-101-induced defects of GDM-HUVECs.

Impact of Diabetes Mellitus

“…7 In order to investigate how diabetes affects endothelial function and miRs in human endothelial cells, Floris and colleagues took the approach of isolating human umbilical vein endothelial cells (HUVEC) from umbilical cords from pregnancies that were complicated by gestational diabetes (GDM) and from healthy control pregnancies. 8 The use of HUVECs from diabetics and non-diabetics is a clever approach to allow studies of diabetes on freshly isolated human endothelial cells, although it is possible that HUVECs exhibit some differences vis-à-vis endothelial cells involved in vascular complications of diabetes. The authors demonstrated that HUVECs isolated from GDM-complicated pregnancies exhibit increased apoptosis and a reduced ability to form capillary networks, as compared with HUVECs from healthy controls.…”

Roles of MicroRNA across Prenatal and Postnatal Periods

“…Transcription, translation, and protein degradation are prominent examples of how gene activity is controlled by miRNAs, considered to be “meta-regulators” [22]. Importantly, miRNAs can target epigenetic regulators, which play a role in fetal metabolic programming [23,24], mediating long-term effects on target cells [24,25], and on developing organs and tissues. Epigenetic factors and miRNAs have been shown to be reciprocally regulated [24,25].…”

“…Importantly, miRNAs can target epigenetic regulators, which play a role in fetal metabolic programming [23,24], mediating long-term effects on target cells [24,25], and on developing organs and tissues. Epigenetic factors and miRNAs have been shown to be reciprocally regulated [24,25]. Thus, miRNAs are recognized as key regulators of diverse biological and developmental processes in eukaryotes (cell proliferation and differentiation, maintenance of tissue identity, apoptosis, immune system development, and responses) and are associated with pathologies, including different types of cancer [26], vascular diseases [27,28], and diabetes [24,29].…”

MIRNAS: Early Prognostic Biomarkers for Type 2 Diabetes Mellitus?

“…miR-101 has been implicated in gestational diabetes mellitus. It targets EZH2, a histonelysine N-methyltransferase enzyme at lysine of histone 3 and inactivates the gene [110]. miR-101 has been shown to be upregulated in serum samples collected from Japanese population [84].…”