PARP1 Stabilizes CTCF Binding and Chromatin Structure To Maintain Epstein-Barr Virus Latency Type

Area of Science:

• Virology
• Epigenetics
• Cancer Biology

Background:

• Epstein-Barr virus (EBV) establishes chronic, latent infections in B cells, with its genome persisting as a chromatinized episome.
• The host insulator protein CTCF plays a role in maintaining EBV latency type by binding to the viral genome.
• CTCF is post-translationally modified by poly(ADP-ribose) polymerase 1 (PARP1), which can alter CTCF's DNA binding and chromatin loop formation capabilities.

Purpose of the Study:

• To investigate the role of PARP1 in regulating EBV latency through chromatin-specific mechanisms.
• To determine if pharmacological inhibition of PARP1 affects EBV latency type.

Main Methods:

• Colocalization studies of PARP1 and CTCF on the EBV genome.
• Analysis of chromatin landscape at the Cp promoter during EBV type III latency.
• Assessment of viral gene expression in response to PARP1 activity modulation.

Main Results:

• PARP1 and CTCF were found to colocalize at specific sites on the EBV genome.
• PARP1 stabilizes CTCF binding and maintains an open chromatin structure at the active Cp promoter during type III latency.
• PARP1 activity is crucial for maintaining latency type-specific viral gene expression.

Conclusions:

• PARP1 plays a critical role in stabilizing CTCF binding and regulating EBV chromatin structure, thereby influencing viral latency.
• PARP1 inhibitors represent a potential therapeutic strategy for EBV-associated cancers, particularly those with type III latency, such as AIDS-related and posttransplant lymphomas.