Figure 5

Transcriptional activity of the human ACVRL1 promoter. (A) Schematic representation of the ACVRL1 promoter fragment cloned into the promoterless pGL2-luc reporter vector with the three TSS. (B) Left, 5'-deleted construct series of the whole sequence obtained by PCR and cloned into pGL2-luc. The size of each construct compared with the size of the whole promoter construct is shown in the scheme. Right, transient transfection of ACVRL1 promoter 5'-deleted constructs in the human endothelial cell line HMEC-1. Transfection efficiency was corrected by relating luciferase activity to β-galactosidase activity. Results are expressed as a percentage of activity respect to the activity of the full length construct (-1,035/+210; 100%) (*p < 0.05, **p < 0.01 versus -1,035/+210 pALK1 construct). (C) Effect of ALK1 ligands TGF-β1 and BMP9 on ACVRL1 promoter activity. HMEC-1 cells were transiently transfected with ACVRL1 5'-deleted mutants, and pretreated with 1 ng/ml TGF-β1 for 3 hours or 0.5 ng/ml BMP9 for 15 hours. Results are shown in fold induction values respect to basal activity. No significant effect on ACVRL1 promoter activity was observed, except a little increase with BMP9 on the -422/+59 construct (*p < 0.05; **p < 0.01; ns = not significant).