Epigenetic Regulation of Cell Adhesion and Communication by Enhancer of Zeste Homolog 2 in Human Endothelial Cells

Abstract

The histone methyltransferase enhancer of zeste homolog 2 (Ezh2) mediates trimethylation of lysine 27 in histone 3, which acts as a repressive epigenetic mark. Ezh2 is essential for maintaining pluripotency of stem cells, but information on its role in differentiated cells is sparse. Whole-genome mRNA expression arrays identified 964 genes that were regulated by >2-fold 72 hours after small interfering RNA-mediated silencing of Ezh2 in human umbilical vein endothelial cells. Among them, genes associated with the gene ontology terms cell communication and cell adhesion were significantly overrepresented, suggesting a functional role for Ezh2 in the regulation of angiogenesis. Indeed, adhesion, migration, and tube formation assays revealed significantly altered angiogenic properties of human umbilical vein endothelial cells after silencing of Ezh2. To identify direct target genes of Ezh2, we performed chromatin immunoprecipitation experiments followed by whole-genome promoter arrays (chromatin immunoprecipitation-on-chip) and identified 5585 genes associated with trimethylation of lysine 27 in histone 3. Comparative analysis with our mRNA expression data identified 276 genes that met our criteria for putative Ezh2 target genes, upregulation by >2-fold after Ezh2 silencing and association with trimethylation of lysine 27 in histone 3. Notably, we observed a striking overrepresentation of genes involved in wingless-type mouse mammary tumor virus integration site (WNT) signaling pathways. Epigenetic regulation of several of these genes by Ezh2 was specifically confirmed by polymerase chain reaction analysis of DNA enrichment after chromatin immunoprecipitation using an antibody specific for trimethylation of lysine 27 in histone 3. Combining mRNA expression arrays and chromatin immunoprecipitation-on-chip analysis, we identified 276 Ezh2 target genes in endothelial cells. Ezh2-dependent repression of genes involved in cell adhesion and communication contributes to the regulation of angiogenesis.

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

“…20,21,27 Consistently, the mRNA levels of EZH2 were reduced in GDM-HUVECs in comparison with control healthyHUVECs ( Figure 3A). Interestingly, we noticed that the EZH2-β isoform was decreased in GDM-HUVECs, whereas Gestational diabetes mellitus (GDM) is associated with expressional changes in microRNA-101 (miR-101) that affect the survival and angiogenic capacities of human umbilical vein endothelial cells (HUVECs).…”

“…A recent report indicated a proangiogenic role for EZH2 in HUVECs 20,25 and identified 946 genes upregulated ≥2-fold because of EZH2 knockdown, 27 in accordance with the EZH2 transcriptional repressive function. Importantly, many of these EZH2-targeted genes are implicated in endothelial dysfunction and cardiovascular disease, 27 which is in line with the hypothesis that a decrease in EZH2 may confer an increased cardiovascular risk profile in the offspring from pregnancies complicated by GDM. If validated in population studies allowing for the follow-up of the children to maturity, this could help scientists understand whether there is any association between what is sensed in HUVECs and the incidence of vascular diseases.…”

Unfolding the pathogenesis of scleroderma through genomics and epigenomics

“…It catalyzes H3K27me3. Transcriptomic studies suggest a relatively high expression of the EZH2 in ECs [104], which regulates the expression of multiple angiogenic pathways [105, 106]. We showed that EZH2 was upregulated at the protein level in SSc ECs compared to normal ECs, accompanied with increased levels of H3K27me3 [107].…”

Enhancer of zeste homolog-2 (EZH2) methyltransferase regulates transgelin/smooth muscle-22α expression in endothelial cells in response to interleukin-1β and transforming growth factor-β2

“…3a and c). As IL1B is a putative EZH2-regulated gene [28], we speculated that IL-1β and EZH2 would form a regulatory feedback loop in endothelial cells. The decrease of EZH2 in IL-1β-stimulated HUVEC could lead to decrease of H3K27me3 at IL1B promoter and hence to an increase in IL1B/IL-1β expression.…”

“…We hypothesized that histone methylation by Polycomb family members epigenetically regulates SM22α expression in endothelial cells. EZH2 modulates endothelial gene expression and is important for endothelial function [28,29]. As SM22α is synergistically induced by IL-1β and TGFβ2 in endothelial cells, we investigated the influence of IL-1β and TGFβ2 on the expression of EZH2 and the downstream role of EZH2 and H3K27me3 in mediating the effects of IL-1β and TGFβ2 and in the regulation of TAGLN/ SM22α expression in endothelial cells.…”