Transcription-coupled AID deamination damage depends on ELOF1-associated RNA polymerase II

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• Adaptive immunity relies on antibody gene diversification through transcription-coupled damage (TCD) introduced by activation-induced cytidine deaminase (AID).
• The precise coordination between transcription and DNA damage/repair mechanisms remains incompletely understood.

Purpose of the Study:

• To elucidate the role of transcription elongation factor 1 (ELOF1) in stabilizing RNA polymerase II (RNAPII) at transcription barriers.
• To investigate ELOF1's function in facilitating transcription-coupled DNA damage and repair processes, particularly in the context of antibody gene diversification.

Main Methods:

• Utilized a genetic screen to identify factors involved in transcription-coupled DNA damage and repair.
• Employed mouse models to assess the impact of ELOF1 deficiency on antibody class switch recombination and somatic hypermutation.
• Investigated the interaction between ELOF1, RNAPII, and DNA damage/repair factors in cellular assays.

Main Results:

• ELOF1 stabilizes paused RNAPII at transcription barriers, creating a platform for DNA damage and repair.
• ELOF1 is essential for AID targeting, and its deficiency leads to defective antibody class switch recombination and somatic hypermutation in mice.
• ELOF1 stabilizes chromatin-bound RNAPII, mechanistically facilitating both TCD and repair, independent of downstream transcription-coupled repair factors.
• Loss of ELOF1 causes dissociation of paused RNAPII from chromatin, impairing the recruitment of factors for DNA damage induction and repair.

Conclusions:

• ELOF1 is a central regulator of transcription-coupled DNA metabolism, bridging transcription elongation with DNA damage and repair.
• ELOF1's stabilization of chromatin-bound RNAPII is critical for initiating and resolving DNA damage during antibody gene diversification.
• The study suggests a functional transition of RNAPII from a transcriptional role to a scaffold for DNA damage and repair processes, mediated by ELOF1.