P53 REPRESSES SV40 TRANSCRIPTION BY PREVENTING FORMATION OF TRANSCRIPTION COMPLEXES

There is now much evidence to suggest that the p53 tumour suppressor p rotein functions to monitor the integrity of the genome. When DNA dama ge is detected, p53 suppresses cell growth to allow repair or directs the cell into apoptosis. The mechanism of action of p53 is as yet uncl ear but recent evidence has accumulated to suggest that p53 might act by regulating gene expression. Consistent with this model, p53 can bot h activate and repress a number of viral and cellular promoters. p53 h as also been shown to bind to the CCAAT-binding Factor and TATA-bindin g protein (TBP), and there is direct evidence that p53 represses in vi tro transcription by preventing TBP from binding DNA. We now provide e vidence that p53 can repress transcription from the SV40 promoter by d isrupting DNA/protein complexes involving transcription factor Sp1.