The goal is to achieve mechanistic understanding of the molecular interactions that regulate the tumor suppressor p53 as a master transcriptional regulator in response to genotoxic stress. Studies have shown that lysine acetylation of p53 plays an important role in the transcriptional activity of p53 that regulates cell cycle arrest, senescence or apoptosis. While multiple acetylation sites in p53 have been reported including K320, K373 and K382, as well as more recently, K120 and K164, specific effects of individual or combined acetylation of these lysine residues on p53 activity remain to be elucidated. It is hypothesized that distinct modifications of p53 including acetylation, methylation, ubiquitination and phosphorylation have differential regulatory effects on p53 transcriptional activity in conjunction with other cellular transcriptional proteins. These studies are expected to enhance our understanding of the molecular mechanisms underlying p53 functions in gene transcriptional regulation. Previous studies in vitro have led to conflicting hypotheses concerning the role of the C-terminal basic region of p53 in its ability to act as a transcription factor. In part, this confusion may be due to a reliance on ectopic overexpression approaches. Multiple approaches including a novel mouse model is being used to examine the requirement for the C-terminal basic region in p53-dependent outcomes in cells and in vivo. Approaches are being used to determine the molecular contributions of p300 and CBP in regulating p53-dependent transcriptional activity and cellular outcomes and to address the relevance of the interactions between p300 and CBP with the C-terminal basic region. The goal is to determine how specific co-activators and post-translational modifications contribute to p53-dependent gene expression as well as cellular outcomes and tumor suppression in vivo.
