The first intron of human H-ras is regulated by p53: Mediation of specific activation by a p53-binding element

We conducted transient reporter gene expression assays to show that the wild-type but not the mutant-type p53 protein positively regulates the expression of the human H-ras gene. This activation of expression is mediated through a specific p53-binding DNA element located in the first intron of the H-ras gene. This element is similar to a previously identified p53-binding element. Without this element, wild-type p53 represses the H-ras promoter, as do several p53 mutants. The repression function is lost when the N-terminal 81 amino acids of the p53 protein are deleted, suggesting that the N-terminus is required for repression. Therefore, p53 seems to regulate the H-ras through both positive and negative mechanisms.