Endogenous aldehyde-induced DNA-protein crosslinks are resolved by transcription-coupled repair

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• DNA-protein crosslinks (DPCs) from aldehydes impede DNA replication and transcription.
• Defects in DPC repair and aldehyde clearance cause progeroid syndromes (e.g., Ruijs-Aalfs syndrome, AMeD syndrome).
• Mechanisms for resolving DPCs during transcription are not well understood.

Purpose of the Study:

• Investigate how cells resolve DPCs that arise during transcription.
• Identify the molecular players involved in transcription-coupled DPC repair (TC-DPCR).
• Elucidate the role of TC-DPCR and aldehyde clearance in preventing genotoxicity.

Main Methods:

• Developed a high-throughput sequencing technique (DPC-seq) for genome-wide DPC mapping.
• Utilized proteomics to identify proteins interacting with DPCs.
• Employed a mouse model deficient in aldehyde clearance and TCR.

Main Results:

• Aldehyde-induced DPCs are efficiently resolved by transcription-coupled repair (TCR).
• The TCR complex, VCP/p97, and the proteasome are essential for removing formaldehyde-induced DPCs.
• TFIIS-mediated cleavage of RNAPII transcripts mitigates transcription obstacles.
• A mouse model showed DPC accumulation in actively transcribed regions when aldehyde clearance and TCR were impaired.

Conclusions:

• Transcription-coupled DPC repair (TC-DPCR) is a critical pathway for resolving DPCs during transcription.
• TC-DPCR and aldehyde clearance are essential for protection against metabolic genotoxins.
• These findings explain the molecular basis of AMeD syndrome and other TCR-related disorders.