Characterization of the murine cyclin-dependent kinase inhibitor gene p27(Kip1)

The cyclin-dependent kinase inhibitor p27(Kip1) plays an important role in regulating cell-cycle progression. p27(Kip1) directly inhibits the catalytic activity of cyclin/cdks (cyclin-dependent kinase) complexes and/or interferes physically with cyclin/cdks activation by CAK. Interestingly, the expression level of p27(Kip1) mRNA was maximal in resting G(0) T-cells and rapidly declined following anti-CD3 activation. We report here the cloning of p27(Kip1) gene from murine genomic DNA and the functional analysis of the promoter of the p27(Kip1) gene. The gene consists of at least three exons and spans more than 5.6 kb of DNA. Primer extension and nuclease S1 protection analysis revealed two major transcription initiation sites. The promoter region lacked a TATA box but contained potential binding sites for the transcriptional factors including two Spl, CRE, Myb and NFkB located at positions -153, -178, -286, -875, and -1011, respectively. To analyze the regulatory mechanisms controlling p27(Kip1) gene expression, we characterized the 5'-flanking region from nt -1609 to +178. The -326 to -615 region contained positive regulatory elements.