Hypoxia-specific upregulation of the endogenous human VEGF-A gene by hypoxia-driven expression of artificial transcription factor

Activation of vascular endothelial growth factor A (VEGF-A) is an attractive approach to treatment of ischemic diseases. Although zinc-finger-based artificial transcription factors (ATFs) were constructed for human VEGF-A and constitutive expression of ATFs upregulated the endogenous VEGF-A gene expression, activation of VEGF-A specifically in ischemic tissues is desirable for therapeutic application of ATF technology. Here, we describe hypoxia-specific activation of human VEGF-A gene by hypoxia-driven expression of the ATF. We constructed a hypoxia-driven promoter for the ATF expression and placed it upstream of the ATF-encoding regions. The resulting hypoxia-driven expression plasmid induced the ATF expression in hypoxia but not in normoxia, and the hypoxia-specific expression of the ATF activated the VEGF-A expression specifically in hypoxia. Thus, the engineered expression system of ATFs may enable activation of VEGF-A expression specifically in ischemic tissues without affecting normal, healthy tissues in vivo.