MEG8 regulates Tissue Factor Pathway Inhibitor 2 (TFPI2) expression in the endothelium

Veerle Kremer,Diewertje I Bink,Anne Yaël Nossent,Sarah Hilderink,Laura Stanicek,Stefan Günther,Reinier A Boon,Eva Van Ingen,Theresa Gimbel

doi:10.1038/s41598-022-04812-z

Abstract

A large portion of the genome is transcribed into non-coding RNA, which does not encode protein. Many long non-coding RNAs (lncRNAs) have been shown to be involved in important regulatory processes such as genomic imprinting and chromatin modification. The 14q32 locus contains many non-coding RNAs such as Maternally Expressed Gene 8 (MEG8). We observed an induction of this gene in ischemic heart disease. We investigated the role of MEG8 specifically in endothelial function as well as the underlying mechanism. We hypothesized that MEG8 plays an important role in cardiovascular disease via epigenetic regulation of gene expression. Experiments were performed in human umbilical vein endothelial cells (HUVECs). In vitro silencing of MEG8 resulted in impaired angiogenic sprouting. More specifically, total sprout length was reduced as was proliferation, while migration was unaffected. We performed RNA sequencing to assess changes in gene expression after loss of MEG8. The most profoundly regulated gene, Tissue Factor Pathway Inhibitor 2 (TFPI2), was fivefold increased following MEG8 silencing. TFPI2 has previously been described as an inhibitor of angiogenesis. Mechanistically, MEG8 silencing resulted in a reduction of the inhibitory histone modification H3K27me3 at the TFPI2 promoter. Interestingly, additional silencing of TFPI2 partially restored angiogenic sprouting capacity but did not affect proliferation of MEG8 silenced cells. In conclusion, silencing of MEG8 impairs endothelial function, suggesting a potential beneficial role in maintaining cell viability. Our study highlights the MEG8/TFPI2 axis as potential therapeutic approach to improve angiogenesis following ischemia.

Highlights

The endothelium is crucial for maintaining a healthy vasculature by controlling the exchange of fluids and molecules, the creation of new vasculature and regulation of vascular tone and blood p ressure[1,2]
We report on a role for Maternally Expressed Gene 8 (MEG8) in the regulation of angiogenic sprouting in Human Umbilical Vein Endothelial Cells (HUVECs)
This study identifies a role for long non-coding RNAs (lncRNAs) MEG8 in the regulation of angiogenesis

Summary

Introduction

The endothelium is crucial for maintaining a healthy vasculature by controlling the exchange of fluids and molecules, the creation of new vasculature and regulation of vascular tone and blood p ressure[1,2]. An important feature of endothelial cells (EC) is their capacity to sense and respond to angiogenic signals These signals regulate the sprouting of vessels from pre-existing ones, a process called angiogenesis. The pro-angiogenic signal Vascular Endothelial Growth Factor (VEGF) induces activation of ECs, which become motile and invasive, forming the front of the vessel sprout. Migration of these so-called tip cells are guided by attractive or repulsive cues. Many lncRNAs are reported to localize to the nucleus and modulate RNA splicing, transcription factor binding and chromatin structure[7,8,9,10,11]. EZH2 has been suggested as binding partner of numerous lncRNAs8,14

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