1: J Biol Chem. 2004 Jun 11;279(24):25093-100. Epub 2004 Mar 25. 

Negative regulation of Chk2 expression by p53 is dependent on the CCAAT-binding
transcription factor NF-Y.

Matsui T, Katsuno Y, Inoue T, Fujita F, Joh T, Niida H, Murakami H, Itoh M,
Nakanishi M.

Department of Biochemistry and Cell Biology, Graduate School of Medical
Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya
467-8601, Japan.

The kinase Chk2 and tumor suppressor p53 participate in an ill defined
regulatory interaction in mammalian cells. The abundance of Chk2 mRNA and
protein has now been shown to be decreased by the induction of p53 in Saos2
cells. Ionizing radiation also triggered the phosphorylation and subsequent
down-regulation of Chk2 in human colorectal HCT116 (p53(+/+)) cancer cells;
irradiation of its isogenic mutant HCT116 (p53(-/-)) cells, which lack
functional p53, induced Chk2 phosphorylation but not its down-regulation. In
addition, HCT116 (p53(+/+)) cells constitutively expressing a dominant negative
p53 (V143A) failed to suppress Chk2 expression after irradiation. Reporter gene
assays in HCT116 (p53(+/+)) cells revealed that wild-type p53 repressed, whereas
a dominant negative p53 mutant increased, the activity of the human Chk2 gene
promoter. Mutational analysis showed that a CCAAT box located between
nucleotides -152 and -138 of the promoter was responsible for its negative
regulation by p53. Electrophoretic mobility shift assays demonstrated that the
transcription factor NF-Y binds to this CCAAT sequence. A dominant negative
mutant of NF-YA abolished the effect of p53 on Chk2 promoter activity. These
results suggest that p53 negatively regulates Chk2 gene transcription through
modulation of NF-Y function and that this regulation may be important for
reentry of cells into the cell cycle after DNA damage is repaired.

PMID: 15044452 [PubMed - indexed for MEDLINE]


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