How T cells destroy virally infected cells and tumour cells
Featured Lab - Dr Gillian Griffiths
Our immune system ensures that our body remains healthy despite continual invasion by bacteria and viruses. We are particularly interested in the function of T cells, which seek out and destroy virally infected cells and tumour cells. The incredible ability of T cells to recognize a target and rapidly destroy it relies on the formation of a special contact or 'synapse' with the target which is initiated at the right place by the movement of a cell structure termed the centrosome. We use microscopy to track this process in fine detail and so map the events that control synapse formation. We also investigate the protein signals that direct these changes, and this has important implications for understanding how the immune system works to fight infection, and how immune diseases can arise.
Our laboratory is interested in understanding the mechanisms that control polarized secretion from cytotoxic T lymphocytes and NK cells. We use cutting-edge imaging, molecular, genetic and biochemical techniques to identify the proteins required for polarized secretion, and to understand the way in which they work.
Using imaging we can see the directed movement of secretory granules (red) as the killer cell (labelled with actin in green) polarizes towards the target (blue):
The versatility and speed of the Andor Revolution XD multipoint scanner, in combination with analysis and presentation capabilities of the Imaris software suite, enable us to capture and narrate the details of this complex story. A nice example of this can be viewed in the YouTube video below.
With these tools we have discovered that the centrosome docks at the immunological synapse and delivers secretory granules to the precise site of secretion so that only the target is destroyed. The speed of the Andor system has allowed us to image through the entire depth of the cells as they interact and image all of. the events that lead to polarised secretion, establishing the temporal relationships between key events leading to secretion at the immunological synapse (Ritter, Asano et al 2015). We can use this information to understand how these mechanisms are disrupted when key proteins are missing in primary immunodeficiencies (Jenkins et al 2014; Hackmann et al 2013), or when particular signalling pathways are disrupted (de la Roche et al 2013).
Of course, the technology for imaging live cells has been improving all the time, and we now have the ability to look at these cells in real time using markers. You can see all these structures in live cells, and it has been a lot of fun to do that. It takes a lot of time, but I’m fortunate to have students and postdocs who really love doing this, as do I. Much of our fixed cell imaging is also carried out on the Andor system, as it acquires the confocal stacks very rapidly allowing us to image many more samples in a session. Our system is fully booked, including the weekends!
Alex Ritter, Gillian Griffiths and Yukako Asano by the lab’s Andor Revolution XD multipoint scanner
Gillian Griffiths is a British cell biologist and immunologist. She was one of the first to show that immune cells have specialised mechanisms of secretion, and identified proteins and mechanisms that control cytotoxic T lymphocyte secretion. As a Professor of Cell Biology and Immunology at the University of Cambridge and the Director of the Cambridge Institute for Medical Research,. Gillian has pioneered the use of cytotoxic T lymphocytes from patients with genetic disorders to study cell biology in a specialised cell type. Through an integrated approach combining genetic, biochemical and imaging approaches, her lab has shown that immune cells use lysosomes as secretory organelles that the centrosome has a unique role in driving formation of the immune synapse, and that Hedgehog signalling is important for this. Her long-term vision is to understand the molecular mechanisms that control polarised secretion from cytotoxic T lymphocytes, and how these fit together to ensure accurate delivery to the immunological synapse.
Ritter AT, Asano Y, Stinchcombe JC, Dieckmann NM, Chen BC, Gawden-Bone C, van Engelenburg S, Legant W, Gao L, Davidson MW, Betzig E, Lippincott-Schwartz J, Griffiths GM. Actin depletion initiates events leading to granule secretion at the immunological synapse. Immunity 42, 864-876. doi: 10.1016/j.immuni.2015.04.013 (2015).
Jenkins, M. R. et al. Distinct structural and catalytic roles for Zap70 in formation of the immunological synapse in CTL. eLife 3:e01310 (2014).
de la Roche, M. et al. Hedgehog signaling controls T-cell killing at the immunological synapse. Science 342, 1247–1250 (2013).
Hackmann, Y. et al. Syntaxin binding mechanism and disease causing mutations in Munc 18-2. Proc. Natl Acad. Sci. USA 110, E4482–4491 (2013).
Ritter, A. T., Angus, K. L. and Griffiths, G. M. The role of the cytoskeleton at the immunological synapse. Immunol. Rev. 256, 107–117 (2013).
Stinchcombe, J. C., Salio, M., Cerundolo, V., Pende, D., Arico, M. and Griffiths, G. M. Centriole polarisation to the immunological synapse directs secretion from cytolytic cells both the innate and adaptive immune systems. BMC Biol. 9, 45 (2011).
Tsun, A., Quereshi, I., Stinchcombe, J. C., Jenkins, M. R., de la Roche, M., Kleczkowska, J., Zamoyska, R. and Griffiths, G, M. Centrosome docking at the immunological synapse is controlled by Lck signaling. J. Cell Biol. 192, 663–674 (2011).