Coordinated Regulation of TIP60 and Poly(ADP-Ribose) Polymerase 1 in Damaged-Chromatin Dynamics

Abstract

fThe dynamic exchange of histones alleviates the nucleosome barrier and simultaneously facilitates various aspects of cellular DNA metabolism, such as DNA repair and transcription. In response to DNA damage, the acetylation of Lys5 in the histone variant H2AX, catalyzed by TIP60, plays a key role in promoting histone exchange; however, the detailed molecular mechanism still is unclear. Here, we show that the TIP60 complex includes poly(ADP-ribose) polymerase 1 (PARP-1). PARP-1 is required for the rapid exchange of H2AX on chromatin at DNA damage sites. It is known that PARP-1 binds dynamically to damaged chromatin and is crucial for the subsequent recruitment of other repair factors, and its auto-poly(ADP-ribosyl)ation is required for the dynamics. We also show that the acetylation of histone H2AX at Lys5 by TIP60, but not the phosphorylation of H2AX, is required for the ADP-ribosylation activity of PARP-1 and its dynamic binding to damaged chromatin. Our results indicate the reciprocal regulation of K5 acetylation of H2AX and PARP-1, which could modulate the chromatin structure to facilitate DNA metabolism at damage sites. This could explain the rather undefined roles of PARP-1 in various DNA damage responses. P osttranslational modifications of histones are a fundamental process for the chromatin remodeling machinery in DNA metabolism, including transcription, DNA replication, and DNA repair (1, 2). These histone modifications either serve as the binding interface for regulatory factors in chromatin reorganization or function as a platform in a signaling cascade, such as in the DNA damage checkpoint response (1, 3). In addition to histone modifications, the incorporation or eviction of histone variants regulates chromatin dynamics and could directly promote DNA metabolism in the context of chromatin (4-9). Thus, it is important to clarify how the histone variants' dynamics at DNA damage sites and their modifications are coordinated upon commitment to each type of DNA metabolism. Such clarification would promote a better understanding of the significance of histone variants, which potentially play active roles, rather than simply functioning as barriers, during DNA metabolism (10).Upon DNA damage, Ser139 (S139) of H2AX, a histone H2A variant, is phosphorylated at DNA damage sites, and the phosphorylated H2AX functions as an anchor to retain DNA damage response (DDR) factors on the DNA damage sites (11-14). We previously reported that the acetylation of H2AX at lysine 5 (K5Ac) is required to facilitate histone H2AX exchange at DNA damage sites and also is necessary for the efficient assembly of NBS1 at these sites by promoting its turnover rate (9, 15). K5 acetylation of H2AX is catalyzed by the histone acetyltransferase TIP60 complex, which coordinates the signaling and repair of DNA damage via chromatin reorganization (9, 16-18). Importantly, the phosphorylation of H2AX on S139 is not required to facilitate H2AX exchange or to promote NBS1 turnover at DNA damage sites (9, 15). These findings indicated the dist...

Identification of regulators of poly-ADP-ribose polymerase inhibitor response through complementary CRISPR knockout and activation screens

“…Out of these, two DNA repair genes previously unconnected to PARPi resistance, namely the histone acetyltransferase KAT5 (also known as TIP60) and E3 ubiquitin ligase HUWE1, drew our attention. Both proteins have roles in cellular processes related to DNA replication and repair and are potential interactors of PARP1 21 , 22 , yet they have not been directly connected to PARPi sensitivity. We first sought to validate these two hits.…”

Post-Translational Modifications of H2A Histone Variants and Their Role in Cancer

“…Less studied modifications of H2A.X are acetylation, methylation and SUMOylation, some of which also contribute to DDR by recruiting repair factors. Acetylation of K5 by TIP60 does not only facilitate ubiquitination at K119 and mobility [ 76 , 77 ], it is also required for the accumulation of the repair factor NBS1 and Poly-ADP-ribosyl-polymerase 1 (PARP1/ARTD1) activity [ 132 , 133 ]. Methylation of K134 is involved in the repair process and contributes to the recruitment of the kinases ATM and ATR [ 79 ], but the function of Suv39H2 as K134 methylase is highly controversial [ 80 ].…”

Expanding functions of ADP-ribosylation in the maintenance of genome integrity

“…An additional line of inquiry has examined the contribution of PARP1 in the exchange rate (incorporation or eviction) of histone variants. A recent study reported that a reciprocal cooperation between the acetylation of H2AX at lysine 5 (K5Ac) catalysed by the acetyltransferase TIP60 complex and PARP1 activation is required to facilitate histone H2AX exchange at damage sites [28]. The acetylation of H2AX-K5 by TIP60 is needed for the dynamic binding of PARP1 to damaged chromatin and the subsequent local synthesis of PAR.…”