Transcription factor KLF6 upregulates expression of metalloprotease MMP14 and subsequent release of soluble endoglin during vascular injury

Abstract

After endothelial injury, the transcription factor Krüppel-like factor 6 (KLF6) translocates into the cell nucleus to regulate a variety of target genes involved in angiogenesis, vascular repair and remodeling, including components of the membrane transforming growth factor beta (TGF-β) receptor complex such as endoglin and activin receptor-like kinase 1. The membrane metalloproteinase 14 (MMP14 or MT1-MMP) targets endoglin to release soluble endoglin and is involved in vascular inflammation and endothelial tubulogenesis. However, little is known about the regulation of MMP14 expression during vascular wounding. In vitro denudation of monolayers of human endothelial cell monolayers leads to an increase in the KLF6 gene transcriptional rate, followed by an upregulation of MMP14 and release of soluble endoglin. Concomitant with this process, MMP14 co-localizes with endoglin in the sprouting endothelial cells surrounding the wound border. MMP14 expression at mRNA and protein levels is increased by ectopic KLF6 and downregulated by KLF6 suppression in cultured endothelial cells. Moreover, after wire-induced endothelial denudation, Klf6+/− mice show lower levels of MMP14 in their vasculature compared with their wild-type siblings. Ectopic cellular expression of KLF6 results in an increased transcription rate of MMP14, and chromatin immunoprecipitation assays show that KLF6 interacts with MMP14 promoter in ECs, this interaction being enhanced during wound healing. Furthermore, KLF6 markedly increases the transcriptional activity of different reporter constructs of MMP14 gene promoter. These results suggest that KLF6 regulates MMP14 transcription and is a critical player of the gene expression network triggered during endothelial repair.Electronic supplementary materialThe online version of this article (doi:10.1007/s10456-016-9495-8) contains supplementary material, which is available to authorized users.

Regulation and role of endoglin in cholesterol‐induced endothelial and vascular dysfunction in vivo and in vitro

“…KLF6 is well known for its role in regulating Eng expression (4,35), and we have shown that the silencing of KLF6 prevents 7K-mediated increase in both Eng mRNA and protein levels. Interestingly, cotransfection of RAW264.7 cells with KLF6 and NF-kB p65 showed an enhanced inflammatory reaction of cells after LPS treatment, suggesting an interplay between KLF6 and NF-kB p65 in inflammatory settings (50,51).…”

Krüppel-like factors in mammalian stem cells and development

“…Another factor, KLF6, also known as tissue remodeling factor, was shown in mice to promote vascular repair after bilateral endoluminal injury to the common femoral artery. This enhanced repair process was accompanied by increased activity of matrix metallopeptidase 14, endoglin and activin receptor-like kinase 1 (ACVRL1), which are involved in angiogenesis and vascular remodeling (Gallardo-Vara et al, 2016;Garrido-Martin et al, 2013). The potential role of KLFs in axonal regeneration has also attracted a lot of attention.…”

Potential Role of Circulating Endoglin in Hypertension via the Upregulated Expression of BMP4

“…Endoglin is a 180-kDa homodimeric transmembrane protein that contains a large extracellular region (561 amino acids) and a short (47 amino acids) cytosolic domain [12,13]. The juxtamembrane region of the endoglin ectodomain can be proteolytically targeted by the matrix metalloprotease 14 (MMP14; MT1-MMP) or by MMP-12 to release a soluble protein (either alone or in complex with exosomes), named sEng which encompasses most of its extracellular region [14][15][16][17][18][19]. Analysis of the three-dimensional structure of the endoglin ectodomain, has revealed the presence of an N-terminal orphan region (OR), and a C-terminal bipartite zona pellucida (ZP) module [20,21].…”

“…The circulating sEng can be shed from membrane-bound endoglin [7,37,38] upon activation by endothelial injury, inflammation, or tumor necrosis factor α (TNF-α) stimuli [16,19,39,40]. Abnormally elevated levels of sEng have been found in several vascular-related pathologies [6,37,38], including preeclampsia, a multisystem disorder of high prevalence in pregnant women marked by the onset of hypertension, proteinuria or systemic endothelial dysfunction.…”