BRCA1 and Tip60 determine the cellular response to ultraviolet irradiation through distinct pathways.

The histone acetyltransferase Tip60 regulates the apoptotic response to ultraviolet (UV) irradiation. A previously suggested mechanism for this regulation consists of the ability of Tip60 to coactivate transcription by the tumor suppressor p53. In this study, we show that Tip60 is required for the early DNA damage response (DDR) to UV, including the phosphorylation of histone 2AX, c-Jun N-terminal kinases (JNKs), and ataxia telangiectasia-related substrates.

Specific inhibition of Mdm2-mediated neddylation by Tip60.

Tip60 is a histone acetyl transferase (HAT) and a cofactor of transcription, but also an interaction partner of the Mdm2 oncoprotein. The functional consequences of this interaction are only partially understood and were further explored in this study. We found that Tip60 is capable of selectively inhibiting the Mdm2-mediated conjugation of Nedd8 to p53, whereas it did not affect p53 ubiquitination.