The histone H2A deubiquitinase USP16 interacts with HERC2 and fine-tunes cellular response to DNA damage [Cell Biology]

October 10th, 2014 by Zhang, Z., Yang, H., Wang, H.

Histone ubiquitination at DNA double strand breaks facilitates the recruitment of downstream repair proteins; however, how the ubiquitination is dynamically regulated during repair and terminated after repair is not well understood. Here we report that the histone H2A deubiquitinase USP16 interacts with HERC2 and fine-tunes the ubiquitin signal during repair, and importantly, is required for terminating the ubiquitination signal after repair. HERC2 interacts with the coiled-coil domain of USP16 through its C-terminal HECT domain. HERC2 knockdown affects the levels of ubiquitinated H2A through the action of USP16. In response to DNA damage, USP16 levels increase and this increase is dependent on HERC2. Increased USP16 serves as a negative regulator for DNA damage-induced ubiquitin foci formation and affects downstream factor recruitment and DNA damage response. The functional significance of USP16 is further manifested in human Down syndrome patient cells, which contain three copies of the USP16 gene and display altered cellular response to DNA damage. Finally, we domonstrated that USP16 could deubiquitinate both H2AK119 and H2AK15 ubiquitination in vitro. Therefore, this study identifies USP16 as a critical regulator of DNA damage response and H2AK15 ubiquitination as a potential target of USP16.