Characterisation of the genotype and phenotype of epithelial cells invaded by the periodontal pathogen Porphyromonas gingivalis.

The presence of the Gram negative anaerobe Porphyromonas gingivalis is consistently associated with the more severe forms of periodontal disease and its ability to invade host epithelial cells is thought to be important in the pathogenesis of the disease. However, not all epithelial cells exposed to P.gingivalis in vitro become infected. We have evidence that bacteria target cells in the S-phase of the cell cycle and so we hypothesise that expression of key genes/proteins associated with that phase mediate enhanced bacterial attachment and invasion. The aim of this PhD project is to investigate this phenomenon further.

Objectives:
1. We have shown that flow cytometry can be used to separate oral epithelial cells that have associated fluorescent P.gingivalis. We will use this technique to identify genes which are differentially expressed in cells associated with P.gingivalis. Any changes will be confirmed by qPCR and protein expression levels will be assessed by Western blotting and immunocytochemistry. Recent advancements in the analysis of single cells (RNAseq) would be a suitable for such studies.
2. To investigate the role of candidate genes identified above in bacterial adhesion and invasion. Gene silencing and knock out techniques will be used to determine their effects on bacterial adhesion and invasion. CRISPR techniques have also recently been optimised and employed in our laboratories.
3. To investigate the mechanism of invasion during S-phase of the cell cycle by analysing differences in cell surface protein expression in synchronised cultures. We will also examine whether such cells have an enhanced ability to endocytose and follow the intracellular signalling pathways involved.
4. To investigate whether selective invasion is a general phenomenon or whether it is bacteria-specific. We will investigate the invasion mechanisms for other pathogenic and commensal bacteria from both oral and skin origin.

The successful candidate will join a vibrant research community within the Dental School where those from both a clinical and non-clinical background interact closely. All the facilities and expertise exist within the School to carry out this work including a modern dedicated cell culture suite and microbiology laboratory. This project represents an exciting opportunity in cellular microbiology which may highlight potential targets to prevent pathogen invasion of host cells and thus has therapeutic application.

Enquiries:
Interested candidates should in the first instance contact (Dr Simon Whawell [Email Address Removed])

How to apply:
Please complete a University Postgraduate Research Application form available here: www.shef.ac.uk/postgraduate/research/apply

Please clearly state the prospective main supervisor in the respective box and select School of Clinical Dentistry as the department.