DNA Damage-Dependent Acetylation and Ubiquitination of H2AX Enhances Chromatin Dynamics

Abstract

Chromatin reorganization plays an important role in DNA repair, apoptosis, and cell cycle checkpoints. Among proteins involved in chromatin reorganization, TIP60 histone acetyltransferase has been shown to play a role in DNA repair and apoptosis. However, how TIP60 regulates chromatin reorganization in the response of human cells to DNA damage is largely unknown. Here, we show that ionizing irradiation induces TIP60 acetylation of histone H2AX, a variant form of H2A known to be phosphorylated following DNA damage. Furthermore, TIP60 regulates the ubiquitination of H2AX via the ubiquitin-conjugating enzyme UBC13, which is induced by DNA damage. This ubiquitination of H2AX requires its prior acetylation. We also demonstrate that acetylation-dependent ubiquitination by the TIP60-UBC13 complex leads to the release of H2AX from damaged chromatin. We conclude that the sequential acetylation and ubiquitination of H2AX by TIP60-UBC13 promote enhanced histone dynamics, which in turn stimulate a DNA damage response.

SUPPLEMENTAL MATERIAL

We thank Y. Masuda, Y. Nakatani, J. Walter, T. Cremer, A. Yasui, T. Shiraki, and H. Kurumizaka for discussions and comments on the manuscript; S. Hatakeyama and K. I. Nakayama for providing the antibody to ubiquitin (FK2); P. Y. Perche for the GFP-H2A.1 construct; T. Kanda and G. Wahl for the H2B-GFP construct; H. Tagami for H2A-FLAG/HA-expressing HeLa cells; R. Waldren for editing the manuscript; and H. Suzuki for technical assistance.

This work was supported by the Hiroshima University 21st Century COE Program and grants-in-aid from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.