Transcriptional activation of human PAI-1 promotor by hypoxia.

The transcriptional activation was measured by a luciferase reporter assay. HepG2 cells were transiently transfected with wild-type and mutated promotor constructs. For each construct wild-type HRE1-5 are indicated. The sequence of the mutations and HREs can be found in Table1. After transfection, the cells were cultured at either 21% or 1% oxygen for 24 hours before the assessment of luciferase activity. In each experiment, luciferase activity of cells cultured in hypoxia was determined relative to that of ambient control cells. Each experiment was performed in triplicate on at least 5 separate occasions. Error bars denote SEM; *P < .05 relative to pGL3PAI-wt12 345. (A) Enhancement of luciferase activity in wild-type promotor construct after incubation at 1% oxygen. (B) Effect of mutations of single HREs on the hypoxia-mediated induction. (C) Capacity of individual wild-type HREs to drive transcriptional expression from the PAI-1 promotor after hypoxic treatment.