Human Molecular Genetics, Vol 6, 277-283, Copyright © 1997 by Oxford University Press
W Liebetrau, A Budde, A Savoia, F Grummt and H Hoehn
The tumor suppressor protein p53 (wtp53) can bind to specific target
sequences and activate transcription of genes adjacent to these DNA
elements. Two p53 binding sites are present in the gene coding for the
Fanconi anemia complementation group C (FAC), one in the promoter region
(from -1295 to -1266) and one in the coding region of FAC (from +1828 to
+1848). Gel shift experiments show that wtp53 binds to the p53 target
sequence in the promoter region of the FAC gene. We have investigated
whether binding of p53 to these target sites may affect expression of the
FAC gene. Transfection experiments show that overexpression of wtp53 in
human diploid fibroblasts and lymphoblasts augments transcription of the
FAC gene up to three-fold. The transfection efficacy was approximately 15%
for both cell types. The FAC expression activity per transformed cell was
stimulated to an estimated level of 18- to 21-fold upon overexpression of
p53. The tumor- derived p53 mutants, His175 and His273, that fail to bind
DNA showed only a reduced stimulatory activity on FAC transcription.
Luciferase assays demonstrated that interaction of p53 with its target site
in the FAC promoter does not modulate the promoter activity. We suggest
that the p53 binding site contributes to, but may not be an absolute
prerequisite for p53-directed transcriptional activation. We conclude that
the FAC gene can be added to the list of genes that interact with p53.
ARTICLES
p53 activates Fanconi anemia group C gene expression
Department of Human Genetics, University of Wuerzburg, Germany.
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