CHARACTERIZATION OF THE MURINE CYCLIN-DEPENDENT KINASE INHIBITOR GENEP27(KIP1)

The cyclin-dependent kinase inhibitor p27(Kip1) plays an important rol e in regulating cell-cycle progression. p27(Kip1) directly inhibits th e catalytic activity of cyclin/cdks (cyclin-dependent kinase) complexe s and/or interferes physically with cyclin/cdks activation by CAK. Int erestingly, the expression level of p27(Kip1) mRNA was maximal in rest ing G(0) T-cells and rapidly declined following anti-CD3 activation. W e report here the cloning of p27(Kip1) gene from murine genomic DNA an d the functional analysis of the promoter of the p27(Kip1) gene. The g ene consists of at least three exons and spans more than 5.6 kb of DNA . Primer extension and nuclease S1 protection analysis revealed two ma jor transcription initiation sites. The promoter region lacked a TATA box but contained potential binding sites for the transcriptional fact ors including two Spl, CRE, Myb and NFkB located at positions -153, -1 78, -286, -875, and -1011, respectively. To analyze the regulatory mec hanisms controlling p27(Kip1) gene expression, we characterized the 5' -flanking region from nt -1609 to +178. The -326 to -615 region contai ned positive regulatory elements.