SDE2 integrates into the TIMELESS-TIPIN complex to protect stalled replication forks.

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Replication fork integrity is vital for genome stability.
• Replication stress can lead to genomic instability.
• The replication fork protection complex (FPC) plays a role in managing replication stress.

Purpose of the Study:

• To investigate the role of SDE2 in maintaining replication fork integrity.
• To elucidate the mechanism by which SDE2 counteracts replication stress.
• To understand the interaction between SDE2, FPC, and other DNA repair proteins.

Main Methods:

• Investigated SDE2 interaction with FPC components, specifically TIMELESS (TIM).
• Utilized knockdown experiments to assess the effects of SDE2 and TIM deficiency on replication forks.
• Analyzed fork progression, stalled fork recovery, CHK1 phosphorylation, and MRE11-dependent degradation of reversed forks.

Main Results:

• SDE2 directly interacts with and stabilizes TIMELESS (TIM), enhancing its localization to replication forks.
• SDE2 knockdown phenocopies TIM deficiency, leading to impaired fork progression, stalled fork recovery, and failed CHK1 phosphorylation.
• Loss of SDE2 or TIM results in excessive MRE11-dependent degradation of reversed forks.

Conclusions:

• SDE2 is essential for maintaining genomic integrity by stabilizing the FPC.
• TIMELESS (TIM) has a newly identified role in protecting stalled replication forks.
• TIM-mediated fork protection may cooperate with BRCA-dependent fork stabilization mechanisms.