Functional characterization of TIP60 sumoylation in UV-irradiated DNA damage response

Abstract

The histone acetyltransferase TIP60 regulates the DNA damage response following genotoxic stress by acetylating histone and remodeling chromatin. However, the molecular mechanisms underlying the TIP60-dependent response to UV-induced DNA damage remain poorly understood. To systematically analyse proteins that regulate TIP60 activity in response to UV irradiation, we performed a proteomic analysis of proteins selectively bound to TIP60 in response to UV irradiation using mass spectrometry and identified a novel regulatory mechanism by which TIP60 orchestrates transcriptional activation of p53-dependent checkpoint response in UV-irradiated cells. The initial step of this pathway involves UV-induced association of TIP60 with SUMO-conjugation enzymes and site-specific sumoylation of TIP60 at lysines 430 and 451 via Ubc9. This sumoylation initiates the relocation of TIP60 from nucleoplasm to the promyelocytic leukemia body, which is essential for the UV-irradiated DNA damage repair response via a p53-dependent pathway. Significantly, inhibition of TIP60 sumoylation by overexpression of non-sumoylatable mutant abrogates the p53-dependent DNA damage response, demonstrating the importance of TIP60 sumoylation in response to UV irradiation. Our biochemical characterization demonstrated that the sumoylation of TIP60 augments its acetyltransferase activity in vitro and in vivo. Thus, this study shed new light on the function and regulation of TIP60 activity in UV-irradiated DNA damage response.

SIRT1 Negatively Regulates the Activities, Functions, and Protein Levels of hMOF and TIP60

“…In addition to acetylation and ubiquitination, TIP60 undergoes sumoylation at K430 and K451, and sumoylation promotes TIP60 HAT activity in response to UV irradiation (13). Also, phosphorylation of S86 and S90 of TIP60 has been shown to facilitate TIP60 activation (10,39).…”

Activation of the SUMO modification system is required for the accumulation of RAD51 at sites containing DNA damage

“…Several lines of evidence suggest the involvement of SUMOylation in the formation of higher-order nuclear architectures. The covalent binding of SUMO to DNA-repair-related proteins, such as RAD52, TIP60, RAP80 and PCNA, is induced upon DNA damage (Hoege et al, 2002;Sacher et al, 2006;Yan et al, 2007;Cheng et al, 2008). The accumulation of UBC9, PIAS1 and PIAS4 could enhance the SUMOylation of DNA-repair proteins around DSBs, which would help to recruit and retain RAD51 around DSBs through its SIM, leading to the formation of damage-induced RAD51 foci.…”

PIASy-mediated Tip60 sumoylation regulates p53-induced autophagy

“…While SUMO modification of Tip60 has been reported, 50 the responsible E3 ligase and the biological consequences are not known. Although PIASy-mediated sumoylation was demonstrated by in vitro experiments, 31 this has been problematic to demonstrate in vivo.…”