Activation of the human p27(Kip1) promoter by IFNalpha 2b.

p27(Kip1) is one of the key regulatory proteins in cell cycle through inhibition of pRB phosphorylation by suppression of the activity of several cyclin/Cdk complexes. The expression of p27(Kip1) has been shown to be controlled by a posttranslational mechanism, although vitamin D(3) and neuronal differentiation can also induce its mRNA. Recently, the p27(Kip1) promoter was isolated and sequenced from a human leukocyte genomic library. In this report, we demonstrate that IFNalpha 2b, activates the human p27(Kip1) promoter-driven luciferase reporter gene in transient expression assays in H82 cells. This induction might involve two IRF 1-like binding sites present in the p27(Kip1) promoter. To our knowledge this is the first report on the direct activation of the human p27(Kip1) promoter by IFNalpha 2b.