Oct-1 Is Involved in the Transcriptional Repression of the von Willebrand Factor Gene Promoter

Abstract

The negative regulation of transcription of the human von Willebrand factor (vWF) gene was investigated in human umbilical vein endothelial cells (HUVECs) and HeLa cells. A fragment spanning −89 to +244 nucleotides (nt), containing the first exon, is active in HUVECs only but not in HeLa cells. The activity of this promoter is sharply reduced by mutagenesis of the GATA binding site at +221. Extension of the upstream sequences from nt −89 to −142 and to −496 results in progressive reduction of the activity of the −89 to +244 promoter identifying a negative regulatory element between nt −142 and −89. A factor present in nuclear extracts from endothelial and nonendothelial cells binds to an AT-rich sequence located between nt −133 and −125. Mutagenesis of the AT-rich sequence interferes with nuclear protein binding and restores the activity of the −142 to +244 fragment to the level of the −89 to +244 promoter. Binding of the nuclear protein to the vWF AT-rich sequence in mobility shift assays is inhibited by competition with a consensus Oct-1 binding site and with a silencer octamer-like sequence from the vascular cell adhesion molecule-1 (VCAM-1) promoter. Subsequent supershift experiments identified Oct-1 as the transcription factor that binds to vWF and VCAM-1 silencer elements. These results indicate that Oct-1 acts as a transcriptional repressor of promoters of genes expressed in endothelial cells. © 1998 by The American Society of Hematology.

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) transcriptional regulation by Oct-1 in human endothelial cells: implications for atherosclerosis

“…Both studies were carried out in HeLa cells, a cervical carcinoma cell line, and not the primary vascular endothelial cells that were used in the present study. Different cells may respond differently to the same stimulus [17]. On the other hand, the transfection of primary endothelial cells with plasmid is more difficult than that of HeLa cells.…”

“…In addition to phosphorylation, on activation, Oct-1 has been demonstrated to regulate, positively or negatively, a variety of tissue-specific genes by recruiting tissue-specific cofactors [22]. In vascular endothelial cells, Oct-1 negatively regulates von Willebrand factor and VCAM-1 (vascular cell adhesion molecule-1) gene expression [17], whereas it positively regulates fgl2/fibroleukin [24], endothelial cell-specific TIE2 [25] and inducible nitric oxide synthase gene expression [26]. As a positively acting transcription factor, Oct-1 has been shown to enhance gene expression through interaction with a variety of DNA-binding protein partners, basal transcription factors or tissue-specific coactivators.…”

A +220 GATA motif mediates basal but not endotoxin-repressible expression of the von Willebrand factor promoter in Hprt-targeted transgenic mice

“…The human VWF promoter contains multiple cis ‐regulatory sequences in the 5′‐flanking region and the first exon that have been shown to positively and/or negatively regulate gene expression in vitro [5,18–23]. The first exon possesses a highly conserved GATA site (AGATAG between +220 and +225).…”

Oct‐1 specifically binds the UEF4 Site of the human AP1‐regulated urokinase enhancer

“…This result suggests that Oct‐1 is normally required to repress the transcriptional activity of the urokinase enhancer. A repressive activity of Oct‐1 has been already reported for other promoters: von Willebrand [31], HIV LTR [32], interleukin‐8 [33], pituitary specific transcription factor Pit1/GHF‐1 [34], human thyrotropin B (hTSHb) [35] and prolactin [36]. This is in keeping with our previous results showing that COM appears to have a negative role in transcription: a deletion of the entire COM separating the PEA3/AP1 and the AP1 separated only by 10–15 bp, in fact, increases the basal transcription rate of the enhancer to the level of a multimerized PEA3/AP1 site [10].…”