Ras induces p21Cip1/Waf1 cyclin kinase inhibitor transcriptionally through Sp1-binding sites.

Journal Article (Journal Article)

p21Cip1/Waf1 cyclin-dependent kinase inhibitor (p21) is inducible by Raf and mitogen-activated protein kinase kinase (MAPKK), but the level of regulation is unknown. We show here by conditional and transient Ras-expression models that Ras induces p21. Induction of p21 in conditionally Ras-expressing cells is posttranscriptional utilizing mitogen-activated protein kinase (MAPK) pathway. Transient, high-level Ras-expression induces transcriptional activation of p21 mediated by a GC-rich region in p21 promoter -83-54 bp relative to the transcription initiation site containing binding sites for Sp1-family transcription factors. Mutation of either Sp1-binding site 2 or 4 in this region decreases the magnitude of induction of promoter activity by Ras, but only the simultaneous mutation of both sites abolishes fully the induction. Electrophoretic mobility shift assays using an oligonucleotide corresponding to Sp1-binding site 2 indicate that both Sp1 and Sp3 transcription factors bind to this region. The results demonstrate that the central cytosolic growth regulator Ras is a potent transcriptional and posttranscriptional inducer of the nuclear growth inhibitor p21.

Full Text

Duke Authors

Cited Authors

  • Kivinen, L; Tsubari, M; Haapajärvi, T; Datto, MB; Wang, XF; Laiho, M

Published Date

  • November 4, 1999

Published In

Volume / Issue

  • 18 / 46

Start / End Page

  • 6252 - 6261

PubMed ID

  • 10597223

International Standard Serial Number (ISSN)

  • 0950-9232

Digital Object Identifier (DOI)

  • 10.1038/sj.onc.1203000


  • eng

Conference Location

  • England