Trim33 masks a non-transcriptional function of E2f4 in replication fork progression

Area of Science:

• Molecular Biology
• Genetics
• Cancer Research

Background:

• Replicative stress is a key driver of genomic instability and tumorigenesis.
• Understanding DNA replication control pathways is crucial for therapeutic strategies.

Purpose of the Study:

• To elucidate the role of the Trim33-E2f4-Recql axis in regulating DNA replication under stress.
• To investigate the impact of this pathway on genome integrity and tumorigenesis.

Main Methods:

• Investigated protein interactions and degradation using ubiquitination assays.
• Analyzed DNA replication fork progression and chromatin recruitment via drug- or oncogene-induced stress models.
• Utilized gene deletion and depletion techniques in cell lines, including Myc-overexpressing models.

Main Results:

• E2f4 recruits Recql to facilitate replication fork progression under stress.
• Trim33 ubiquitin ligase targets E2f4 for degradation in unperturbed cells.
• Replicative stress reduces Trim33-dependent ubiquitination, promoting E2f4-Recql interaction and DNA synthesis recovery.
• Trim33 deletion accelerates replication under stress, impairing checkpoint signaling and DNA repair.
• Trim33 depletion in Myc-overexpressing cells increases DNA damage and delays tumorigenesis.

Conclusions:

• The Trim33-E2f4-Recql axis is a critical regulator of DNA replication fork progression, particularly on transcriptionally active chromatin.
• This pathway plays a significant role in maintaining genome integrity and influences the pace of Myc-driven tumorigenesis.