Universität zu Köln

Spiliopoulou, Xenia Alice (2026). Role of p300 in human papillomavirus type 8 (HPV8)-mediated skin tumorigenesis. PhD thesis, Universität zu Köln.

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Abstract

Viral oncogenes can reshape the host-cell transcriptome to promote transformation, yet the mechanisms by which HPV E6 oncogenes exert such control remain poorly understood. Beta- HPV infection is associated with cutaneous squamous cell carcinomas (cSCCs) in immunosuppressed organ-transplant recipients and patients with the rare hereditary disease Epidermodysplasia verruciformis. Previous work from our group showed that beta-HPV8-E6 physically interacts with the transcriptional co-activator p300 and that this interaction is crucial for skin tumorigenesis. This study aimed to elucidate how HPV8-E6 modulates p300 and the consequences for HPV8-E6-driven tumorigenesis. In this work, the HPV8-E6-binding domain within p300 was mapped to a 59-amino-acid fragment spanning residues 332–390 and to a 26-amino-acid fragment spanning residues 1789–1814. These minimal binding regions may provide a basis for inhibitors targeting the HPV8-E6/p300 interaction. To investigate how HPV8-E6 modulates the p300 interactome, p300-1 (aa 2–439) was used as bait in TurboID-based proximity proteomics. GO analysis revealed an enrichment of proteins involved in lysine-acetylated histone binding, DNA damage repair, and DNA replication. We focused on DPF2, the epigenetic reader subunit of the chromatin-remodeling CBAF complex, whose proximity to p300-1 increased in the presence of HPV8-E6. Co-IPs suggested that HPV8- E6 stabilizes a ternary complex with DPF2 and p300. CRISPR-Cas9-mediated DPF2 knockout and RNA-seq analysis were used to investigate DPF2-dependent transcription in human N/Tert keratinocytes. Matrix metalloproteinase 7 (MMP7) was among the most strongly affected genes and was induced by HPV8-E6, with increased expression also detected in Epidermodysplasia verruciformis-associated cSCCs. ChIP-seq analysis revealed increased p300 signals close to the MMP7 transcription start site in HPV8-E6-expressing cells compared with empty-vector keratinocytes. In addition, DPF2 and p300 signals were simultaneously increased at a putative promoter-distal MMP7 regulatory region. This region overlapped with chromatin enriched for histone H3 lysine 27 acetylation, suggesting that HPV8-E6-mediated transcriptional activation of MMP7 is associated with altered p300 and DPF2 binding. In summary, our findings suggest that the small non-DNA-binding HPV8-E6 oncogene modulates the p300 interactome and DPF2-dependent transcriptional regulation. This involves altered chromatin association of p300 and DPF2 at MMP7 regulatory regions and increased MMP7 expression. MMP7 induction may contribute to cellular transformation and HPV8-E6-driven skin tumorigenesis.