Regulation of Chromatin Architecture by the PWWP Domain-Containing DNA Damage-Responsive Factor EXPAND1/MUM1

Abstract

Summary Dynamic changes of chromatin structure facilitate diverse biological events, including DNA replication, repair, recombination, and gene transcription. Recent evidence revealed that DNA damage elicits alterations to the chromatin to facilitate proper checkpoint activation and DNA repair. Here we report the identification of the PWWP domain-containing protein EXPAND1 as an architectural component of the chromatin, which in response to DNA damage, serves as an accessory factor to promote cell survival. Depletion of EXPAND1 or inactivation of its PWWP domain resulted in chromatin compaction. Upon DNA damage, EXPAND1 rapidly concentrates at the vicinity of DNA damage sites via its direct interaction with 53BP1. Ablation of this interaction impaired damage-induced chromatin decondensation, which is accompanied by sustained DNA damage and hypersensitivity to genotoxic stress. Collectively, our study uncovers a chromatin bound factor that serves an accessory role in coupling damage signaling with chromatin changes in response to DNA damage.

Epstein–Barr virus BZLF1 protein impairs accumulation of host DNA damage proteins at damage sites in response to DNA damage

“…This is consistent with a previous study, which reports that 53BP1 recruits to DSBs through its tandem Tudor domain but not BRCT domain. 35 Our results therefore do not support a role of BZLF1 as a competitor of 53BP1 for binding to chromatin.…”

“…22 To determine whether 53BP1 interacts with BZLF1 through BRCT tandem repeats, we performed immunoprecipitation experiment in cells that were co-transfected with plasmids expressing Flag-BZLF1 and HA-53BP1 or HA-53BP1 without the BRCT domain (HA-53BP1ΔBRCT). 35 The results showed that Flag antibodies could only pull down HA-53BP1 but not HA--53BP1ΔBRCT (Figure 1d), which confirmed that 53BP1 associates with BZLF1 through its BRCT domain. To further discriminate between the two possible mechanisms by which BZLF1 interferes with the recruitment of 53BP1 to IRIF, HONE1 cells were transfected with expression plasmids encoding HA-53BP1ΔBRCT and then assayed for 53BP1 recruitment at DNA damage sites following IR.…”

USP28 Is Recruited to Sites of DNA Damage by the Tandem BRCT Domains of 53BP1 but Plays a Minor Role in Double-Strand Break Metabolism

“…Notably, previous work established that 53BP1 BRCT domains also mediate binding to p53 (53)(54)(55) and MUM1/ EXPAND1 (39). It will therefore be interesting in future studies to assess whether 53BP1 binding to p53 or MUM1 is affected by USP28 status or vice versa.…”

Critical Roles of Ring Finger Protein RNF8 in Replication Stress Responses

“…Chromatin Fractionation and Immunoprecipitation Experiments-Preparation of chromatin fractions were described previously with modifications (22). Briefly, cells were harvested at the indicated times after treatment and washed once with PBS.…”