Acute and long-term effects of mutant p53 in vivo [MEF]

The specific roles of mutant p53’s dominant-negative (DN) or gain-of-function (GOF) properties in regulating acute response and long-term tumorigenesis is unclear. Using “knock-in” mouse strains expressing varying R246S mutant levels, we show that DN effect on transactivation is universally observed after acute p53 activation whereas the effect on cellular outcome is cell-type specific. Reducing mutant p53 levels abrogated the DN effect. Mutant p53’s DN effect protected against radiation-induced death, but did not accentuate tumorigenesis. Furthermore, the R246S mutant did not promote tumorigenesis compared to p53-/- mice in various models, even in the absence of MDM2, unlike the R172H mutant. Together, these data demonstrate that mutant p53’s DN property only affects acute responses, whereas GOF is not universal, being mutation-type specific. Transcriptomes of mouse embryonic fibroblasts harvested from embyros of different p53 genotypes were profiled. A total of 6 primary clones of MEFs were used and these cells were transformed with E1A/Ras. Data was analysed by mixed model ANOVA using Partek.