Re-wiring epithelial homeostasis: Papillomavirus targeting of the Hippo signalling pathway

Background: HPV infection differs significantly from that of other viruses as it is tied to the differentiation status of the infected keratinocyte. As an obligate intracellular parasite with limited genetic coding capacity HPV must manipulate processes in the host cell to establish a productive infection. Aberrant manipulation of these host processes by HPV is linked to the development of anogenital and oral cancers, and as such generates a global disease burden. Accordingly, the study of HPV provides a tractable model system to study the role of host signalling pathways that play crucial roles in epithelial biology.

This research will focus on the recently discovered Hippo signalling pathway, which regulates epithelial homeostasis.

Objectives and experimental approach: Combine primary cell culture models with a genetic/cellular approach to study the role of Hippo signalling in the HPV lifecycle.
1. Impact of HPV infection on components of the Hippo pathway including upstream protein kinases and downstream transcription factors.
2. Contribution of the pathway to HPV replication using small molecule inhibitors and expression of dominant active/negative mutants.
3. Identify which virus encoded protein(s) subvert Hippo using transient transfection of individual genes, genetic manipulation of the full-length virus and mutagenesis of the gene product.

Novelty: Using three dimensional organotypic raft cultures of primary keratinocytes permits the study of the HPV life cycle in unprecedented temporal detail. The role of Hippo signalling in the HPV life cycle has not previously been explored and to our knowledge the work is not being undertaken elsewhere.

Timeliness: Hippo signalling is still poorly characterised in comparison to many other signal transduction pathways. Despite this, it is clear that it plays a pivotal role in epithelial homeostasis. We will use a virus to increase our understanding of this pathway. Data generated from this project will provide new insights into fundamental biological processes.

This project fits within the BBSRC remit of "World class underpinning bioscience". The project aims to understand the fundamental biological mechanisms by which HPV is able to manipulate a recently identified, and therefore poorly characterized, signalling pathway. The cell biological basis of subversion will be identified and the impact on keratinocyte gene expression and physiology will be assessed. Moreover the importance for the virus life cycle will be ascertained. Ultimately, this project will provide a more detailed understanding of the role of proliferation and differentiation pathways in keratinocytes and of the host pathogen response. The results of this project will therefore be of interest to a number of research parties including, but not restricted to, those working on tumour viruses, fundamental cell biologists studying components of the Hippo pathway and researchers working on epithelial homeostasis.