Differentiation-Dependent Proximity Proteomics Identifies Novel Host Factors Linked to HPV16 E2 Function

Area of Science:

• Virology
• Molecular Biology
• Cancer Research

Background:

• Human papillomavirus 16 (HPV16) causes significant cancers and relies on its E2 protein for critical functions.
• The E2 protein's interactions with host factors are essential for viral replication and genome maintenance.
• Understanding these interactions, especially in differentiating cells, is key to viral persistence.

Purpose of the Study:

• To comprehensively map the HPV16 E2 protein's interactome in both undifferentiated and differentiating keratinocytes.
• To identify novel host factors interacting with HPV16 E2 and TOPBP1.
• To elucidate the role of these interactions in viral genome stability during differentiation.

Main Methods:

• Utilized TurboID-based proximity labeling to identify HPV16 E2-associated proteins.
• Employed mass spectrometry to analyze protein-protein interactions.
• Validated key interactions using proximity ligation assays and functional studies in keratinocyte models.

Main Results:

• Identified a network of known and novel host factors associated with HPV16 E2, including chromatin regulators, DNA repair proteins, and nucleolar components.
• Revealed a significant overlap between the interactomes of HPV16 E2 and TOPBP1.
• Discovered nucleolin (NCL) as a differentiation-dependent E2 partner, stabilized by TOPBP1, essential for episomal genome maintenance.

Conclusions:

• Established a cooperative E2-TOPBP1-NCL axis critical for HPV16 genome stability during epithelial differentiation.
• Demonstrated that HPV16 hijacks host factors for genome maintenance, replication, and persistence.
• Highlighted this axis as a potential target for novel antiviral interventions.