Regulation of endogenous gene expression with a small-molecule dimerizer.

Artificial transcription factors containing designer zinc-finger DNA-binding domains (DBDs) have been used to activate or repress expression of a growing number of endogenous genes. We have combined targeted zinc-finger DBD technology with a dimerizer-regulated gene expression system to permit the small-molecule control of endogenous gene transcription. We constructed a dimerizer-responsive transcription factor that incorporates an artificial zinc-finger DBD targeted to the promoter of the human VEGF gene. Introduction of this activator into human cells allowed expression of the chromosomal VEGF gene to be induced by a small-molecule dimerizer compound consisting of a nonimmunosuppressive rapamycin analog. We found that by directly regulating zinc-finger protein (ZFP) activity, we could circumvent difficulties encountered in the generation of cell lines stably expressing conventional unregulated activators. Dimerizer-dependent VEGF induction was rapid, tight, and dose dependent, and resulted in VEGF protein expression levels several-fold greater than those produced by the natural hypoxic response.