Che-1 modulates the decision between cell cycle arrest and apoptosis by its binding to p53.. Homo sapiens

The tumor suppressor p53 is mainly involved in the transcriptional regulation of a large number of growth-arrest- and apoptosis-related genes. However, a clear understanding of which factor/s influences the choice between these two opposing p53- dependent outcomes remains largely elusive. We have previously described that in response to DNA damage, the RNA polymerase II binding protein Che-1/AATF transcriptionally activates p53. Here, we show that Che-1 binds directly p53. This interaction essentially occurs in the first hours of DNA damage, whereas it is lost when cells undergo to apoptosis in response to post-transcriptional modifications. Moreover, Che-1 sits in a ternary complex with p53 and the oncosuppressor Brca1. Accordingly, our analysis of genome-wide chromatin occupancy by p53 revealed that p53/Che1 interaction results in preferential transactivation of growth-arrest p53 target genes over its pro-apoptotic target genes. Notably, exposure of Che-1+/- mice to ionizing radiations resulted in enhanced apoptosis of thymocytes, compared to wild-type mice. These results confirm Che-1 as an important regulator of p53 activity and suggest Che-1 to be a promising yet attractive drug target for cancer therapy. Overall design: ChIP-Seq for p53 in control (DNA damage, IR) and Che-1 depleted Hct116 cells