Identification of promoter elements responsible for transcriptional inhibition of polo-like kinase 1 and topoisomerase IIalpha genes by p21(WAF1/CIP1/SDI1).

Hongming Zhu, Bey Dih Chang, Takeshi Uchiumi, Igor B. Roninson

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Induction of p21 (WAF1/CIP1/SDI1), a physiological mediator of cell cycle arrest, inhibits multiple genes involved in cell division. We have investigated the determinants of p21- mediated inhibition of two of these genes, polo-like kinase 1 (PLK1) and topoisomerase IIalpha (TOPO IIalpha) p21 expression from an inducible promoter in human HT1080 cells rapidly decreases cellular levels of PLK1 and TOPO IIalpha promoters in transient and stable transfection assays. Promoter mutagenesis studies show that inhibition of the PLK1 promoter by p21 is mediated in part by tandem sequences CDE (cell cycle-dependent element) and CHR (cell cycle genes homology region). p21 response of the TOPO IIalpha promoter inhibition and the effects of promoter mutations differ under the conditions of growth arrest produced by p21 induction or by mimosine, a cell cycle inhibitor that increases p21 RNA but not protein expression in HT1080 cells. These results indicate that inhibition of cell division-associated genes by p21 is mediated by different but overlapping mechanisms, which are not a general con-sequence of cell cycle arrest.

Original languageEnglish
Pages (from-to)59-66
Number of pages8
JournalCell cycle (Georgetown, Tex.)
Issue number1
Publication statusPublished - Jan 1 2002
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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