Deletion analysis and relative expression of the human VWF proximal promoter region in VWF-expressing and non–VWF-expressing cells. (A) Diagrammatic representation of the proximal VWF promoter including the first noncoding exon cloned upstream of the luciferase gene. Nucleotide sequence numbers are indicated with respect to the human VWF transcription start site. Open boxes represent GATA sites at nts –81 and +220. A GATA element (▦) located at nt +53 appears to enhance transcription in megakaryocytes.22 The Ets element (▪) and the transcriptional start site (arrow) are indicated. (B) The mean fold increase in normalized luciferase expression of the promoter construct containing nts –91 to +229, relative to the promoterless pGL2 Basic construct, transfected into VWF-producing and -nonproducing cells. (C) Mean normalized luciferase expression relative to the full-length VWF promoter (nts –91/+229) is expressed as a percentage. n represents the number of experiments for each of the cell types. Error bars indicate the standard error of the mean. Results of t tests between specific deletion constructs and the full-length proximal promoter are shown, and a P value is considered statistically significant when P < .05.
