Building and breaking epithelial organs: an optogenetic approach
Supervisor:Dr. Clare Buckley
Second Supervisor: Dr. Kristian Franze
Second Supervisors DepartmentPDN
My lab uses optogenetic and live confocal imaging approaches within the zebrafish neural tube to manipulate the polarity of single cells using light. We investigate how cell polarity is involved in building organs during development and breaking them during disease.
During development, most organs in the body arise from epithelial tubes, made from polarised cells. The strict apico-basal polarity of these cells is important for tissue integrity and later cell differentiation. The process by which epithelial tubes are polarised de novo from initially unpolarised cells is a fundamental principle of body patterning but is still not well understood. Conversely, once the epithelium is established, the process by which polarity is lost is relevant both for diseases such as carcinoma and for developmental processes such as epithelial to mesenchymal transition (EMT). Understanding the cell biology at the root of these polarity transitions is therefore an important research goal.
Up until now it has been challenging to design experiments to test the sufficiency of polarity proteins to drive tissue organisation. To solve this problem, we use optogenetics to reversibly localise proteins and signalling to specific subcellular positions with high spatiotemporal control. This allows us to test the importance of protein LOCATION, rather than just the necessity of protein function.
There are several projects available within the lab. For example:
1. How are cell polarity and division linked during development?
During epithelial establishment, cell division and polarity are known to be strongly linked but our recent work discovered a novel mechanism of division-independent de novo cell polarisation. This highlighted the need to further explore the interrelationship between cell polarity and cell division in the context of a whole organ. This is only possible using methods such as optogenetics to move key polarity and division regulators.
2. What is the role of polarity dysregulation in tissue disruption?
There is emerging evidence that polarity defects might be upstream of tissue disorganisation at the onset of diseases such as cancer. However, it is still unclear whether polarity defects are a cause or consequence of tissue disorganisation. We will test the role of polarity dysregulation in tissue disruption by optogenetically manipulating polarity-linked signalling pathways such as the cancer-linked PI3K pathway in individual cells within the whole neural tube.
3. Analysing mechanical properties during neural tube polarisation
This project aims to investigate the mechanical properties within the developing zebrafish neural rod as polarity arises. We will use in vivo atomic force microscopy (iAFM) techniques in the Franze lab to measure stiffness gradients and exert compressive forces across both the developing zebrafish embryo and an in vitro ‘neural tube’. We aim to determine whether mechanical force influences neuroepithelial polarisation.
This work will significantly advance understanding of fundamental mechanisms driving cellular integration within an epithelial organ. It will also develop a biologically relevant in vivo model in which disease-linked signalling can be precisely and reversibly manipulated at a subcellular level within a whole tissue. In combination with transcriptomics approaches, this will allow us to start to unravel the complex signalling pathways involved in both epithelial development and epithelial disease in the context of cellular behaviour, therefore providing clues to the mechanisms of disease initiation. We hope to determine whether the cellular and molecular processes responsible for building an epithelium during development also responsible for breaking it during disease.