USP7 is essential for maintaining Rad18 stability and DNA damage tolerance

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Rad18 is a key regulator of DNA damage response (DDR) pathways, balancing replication fidelity and genome stability.
• Rad18 facilitates translesion synthesis (TLS) for damaged genome replication but can be error-prone.
• Loss of Rad18 leads to replication fork collapse and incomplete genome replication.

Purpose of the Study:

• To identify regulators of Rad18 protein levels.
• To investigate the role of USP7 in the DNA damage response pathway involving Rad18.
• To understand how USP7 impacts genome stability.

Main Methods:

• Investigated the interaction between USP7 and Rad18.
• Assessed the effect of USP7 depletion on Rad18 protein levels.
• Analyzed UV-induced PCNA mono-ubiquitylation and Pol η recruitment.
• Examined nascent DNA strand elongation and DNA damage tolerance in USP7-depleted cells.
• Performed in vitro and in vivo experiments to study ubiquitin chain disassembly.

Main Results:

• USP7 was identified as a critical regulator of Rad18 protein levels.
• Loss of USP7 destabilizes Rad18, compromising UV-induced PCNA mono-ubiquitylation and Pol η recruitment.
• USP7 depletion resulted in failed nascent daughter strand DNA elongation and reduced DNA damage tolerance.
• USP7 directly associates with Rad18 and disassembles Rad18-dependent poly-ubiquitin chains.

Conclusions:

• USP7 is a novel component of the cellular DNA damage response.
• USP7 plays a crucial role in maintaining genome stability by regulating Rad18 levels and activity.
• USP7-mediated regulation of Rad18 is essential for efficient DNA damage tolerance and replication fork protection.