Differentiation-dependent proximity proteomics identifies novel host factors linked to HPV16 E2 function.

Area of Science:

• Virology
• Molecular Biology
• Cancer Research

Background:

• Human papillomaviruses (HPVs) cause significant cancers and rely on host DNA repair factors for replication.
• The HPV16 E2 protein is vital for viral genome replication, maintenance, and DNA damage response.
• Understanding E2 interactions with host proteins, especially during differentiation, is key to viral persistence.

Purpose of the Study:

• To comprehensively map the HPV16 E2 protein interactome in differentiating keratinocytes.
• To investigate the role of host factor TOPBP1 in E2 interactions and viral genome maintenance.
• To identify novel host factors critical for HPV16 replication and stability.

Main Methods:

• Utilized TurboID proximity labeling in stable keratinocyte lines expressing tagged HPV16 E2.
• Performed mass spectrometry to identify E2-associated proteins.
• Validated interactions using proximity ligation assays and functional studies.

Main Results:

• Identified known and novel host factors interacting with HPV16 E2, including chromatin regulators and DNA repair proteins.
• Demonstrated substantial overlap between HPV16 E2 and TOPBP1 interactomes.
• Discovered nucleolin (NCL) as a differentiation-dependent E2 partner, stabilized by TOPBP1, essential for episomal genome maintenance.

Conclusions:

• The study reveals a cooperative E2-TOPBP1-NCL axis critical for HPV16 genome stability during differentiation.
• HPV16 hijacks host chromatin and DNA repair networks for viral genome maintenance and replication.
• This axis represents a potential new target for antiviral interventions against HPV infections.