Cell polarity is a central feature of most if not all cells across species. Polarity can be understood as the unequal distribution of molecules, organelles and other cellular features allowing cells to organise functions and physiological outputs according to this axis of polarisation. For instance, epithelial cells secrete and absorb molecules, migratory cells crawl, and neurons orchestrate information flow according to their axis of polarisation.
Perhaps not surprising, deregulated polarity is detrimental to the normal function of cells and associated with a range of human diseases. Cell polarity is largely controlled by an evolutionarily conserved protein complex and atypical protein kinase C (aPKC) is one of the key polarity effectors and known to be deregulated in many cancers. Intriguingly, loss of aPKC has been further shown to trigger defective immune signalling eventually leading to malignant growth in the intestinal epithelium. How aPKC is regulated is largely unclear. Therefore, understanding the regulatory mechanisms of aPKC and its link to immune signalling and cancer is of fundamental and biomedical interest.
In this interdisciplinary PhD project, the successful candidate will be working on the regulatory mechanisms that activate and control aPKC in model systems, the neural stem cells of the developing brain of Drosophila as well as epithelial tissues of the fly. The Januschke lab recently studied the role of aPKC in establishing cell polarity and regulating cell fate in the neural stem cells of the fly using state-of-the-art live tissue microscopy, genetics and chemical genetics (1, 2). In this project the regulation of aPKC will be studied focussing on its interaction dynamics using FLIM/FRET microscopy. This interdisciplinary also offers the scope to study cell polarity regulation and immune signalling. The Moraga lab uses protein engineering techniques to study the dynamics of immune signalling (3) and in this project specific reporters and tools to monitor and interfere with aPKC function based on nanobody technology will be developed and tested in flies and human cell culture models. Using a surface display nanobody isolation pipeline in yeast, nanobodies with specific functionality can be isolated, further engineered, genetically encoded and used as probes and reporters in cells. The project will develop such nanobody-based tools to manipulate and monitor aPKC signalling in the context of cell polarity regulation focussing on evolutionarily conserved aspects of aPKC function.
This project therefore offers training in genetics, chemical genetics, molecular biology, CrispR, nanobody technologies, protein engineering and microscopy exposing the candidate to key methodology in a biomedically relevant context. Thus, this project will equip the successful candidate equally well for careers in academic and industry.
1. Hannaford MR, Ramat A, Loyer N, Januschke J. aPKC-mediated displacement and actomyosin-mediated retention polarize Miranda inDrosophilaneuroblasts. eLife. 2018;7:166.
2. Hannaford M, Loyer N, Tonelli F, Zoltner M, Januschke J. A chemical-genetics approach to study the role of atypical Protein Kinase C in Drosophila. Development. 2019;146(2):dev170589.
3. Gorby C, Sotolongo Bellón J, Wilmes S, Warda W, Pohler E, Fyfe PK, et al. Engineered IL-10 variants elicit potent immunomodulatory effects at low ligand doses. Sci Signal. 2020;13(649).