Control of secretion at the immunological synapse
Cells of the immune system protect the body against pathogens. If cells in our bodies are infected by viruses, or become cancerous, then killer cells of the immune system identify and destroy the affected cells. Cytotoxic T cells (CTLs) are very precise and efficient killers. They are able to destroy infected or cancerous cells, without destroying healthy cells surrounding them. We aim to uncover the mechanisms controlling secretion from CTL and natural killer (NK) cells. By understanding how this works, we can develop ways to control the 'killer' cells of the immune system. This will allow us to find ways to improve cancer therapies, and ameliorate autoimmune diseases caused when killer cells run amok and attack healthy cells in our bodies.
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):
We use 3D live imaging in order to capture events across the cell and examples of CTL killing are available on these links:
We 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. Centrosome docking at the plasma membrane is very unusual, occurring during cilia formation, and our work has revealed striking similarities between the immunological synapse and cilia formation:
Most recently, we have extended these findings to show that Hedgehog signalling 'pre-arms' CTLs for the centrosome polarization that is required for granule delivery (de la Roche et al. Science 2013).
Clinical collaborations have a very important role in identifying proteins required for secretion and understanding how these proteins work. Our studies have focused on Familial Hemophagocytic Lymphohistiocytosis (FHL), a disease in which secretion of lytic proteins from CTLs and NK cells is disrupted, and the cells fail to kill. Loss of perforin, Rab27a, Munc13-4, 18-2 and syntaxin 11 all lead to loss of CTL secretion and we wish to determine the interactions that allow these proteins to control polarized secretion from these cells. Our studies have allowed us to understand these interactions at the molecular level and revealed a chaperone role for Munc 18-2 in delivering syntaxin 11 to the plasma membrane (Hackmann et al. PNAS 2013).
An exciting new area in the lab is our part in the Infection, Immunity and Immunophenotyping (3i) consortium with the Wellcome Trust Sanger Institute, Kings College London, Oxford and Manchester. Our lab is screening all mutations for loss of CTL secretion, with data being made available through the WTSI website.
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.
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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).
Griffiths, G. M., Tsun, A. and Stinchcombe, J. C. The immunological synapse: a focal point for endocytosis and exocytosis. J. Cell Biol. 189, 399–406 (2010).
Cetica, V., Santoro, A., Gilmour, K. C., Sieni, E., Beutel, K., Pende, D., Marcenaro, S., Koch, F., Grieve, S., Wheeler, R., Zhao, F., zur Stadt, U., Griffiths, G. M. and Aricò, M. STXBP2 mutations in children with familial hemophagocytic lymphohistiocytosis type 5. J. Med. Genet. 47, 595–600 (2010).
Jenkins, M. R., Tsun, A., Stinchcombe, J. C. and Griffiths, G. M. The strength of T cell receptor signal controls the polarization of cytotoxic machinery to the immunological synapse. Immunity 31, 621–631 (2009).
Stinchcombe, J. C., Majorovits, E., Bossi, G., Fuller, S. and Griffiths, G. M. Centrosome polarisation delivers secretory granules to the immunological synapse for secretion. Nature 443, 462–465 (2006). Erratum in: Nature 444, 236 (2006).