Activation of the Human p27Kip1 Promoter by IFNα 2b

Abstract 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 IFNα 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 IFNα 2b.