Nucleotide excision repair-initiating proteins bind to oxidative DNA lesions in vivo

Area of Science:

• Molecular Biology
• DNA Repair Mechanisms
• Cellular Stress Response

Background:

• Base excision repair (BER) is crucial for removing oxidative DNA damage, like 8-oxo-7,8-dihydroguanine.
• Emerging evidence suggests roles for transcription-coupled nucleotide excision repair (TC-NER) factor CSB and global genome NER initiator XPC in protecting against oxidative DNA damage.

Purpose of the Study:

• To investigate the in vivo recruitment of XPC and CSB to oxidative DNA lesions using live-cell imaging.
• To determine if XPC and CSB function independently of downstream NER factors in repairing oxidative DNA damage.

Main Methods:

• Live-cell imaging techniques were employed to visualize the dynamic recruitment of proteins to sites of induced oxidative DNA damage.
• The accumulation of downstream NER factors at damage sites was assessed in the presence and absence of XPC and CSB.

Main Results:

• XPC and CSB showed rapid and significant recruitment to sites of oxidative DNA lesions in living cells.
• Downstream NER factors did not accumulate at damage sites, indicating a NER-independent role for XPC and CSB.
• CSB displayed distinct, transcription-dependent kinetics in the nucleolus and nucleoplasm.

Conclusions:

• CSB and XPC are involved in the in vivo repair of oxidative DNA lesions, independent of the canonical NER pathway.
• CSB's transcription-dependent localization suggests a direct role in repairing oxidative lesions associated with different RNA polymerases.