Integrin nano-adhesions, the molecular clutch and actin dynamics in high speed T cell migration

Student thesis: Doctoral ThesisDoctor of Philosophy


T cells navigate the body using constant actin flow, which transiently engages with a spatially and mechanically controlled ‘molecular clutch’ to produce torque and forward cell movement. The clutch is composed of affinity regulated integrin, actin linkers and phospho-regulators, modulated on the nanoscale as T cells move through blood vessels, tissues and lymph nodes. Cells with a point mutation in a gene linked to integrin signalling (PTPN22) exhibit increased adhesion and migration, and in humans the same mutation predisposes for seven different autoimmune diseases. Here, super resolution localisation microscopy (SLM) in 2D and 3D is used to investigate nano-clustering behaviour in primary effector T cells, while live-TIRF microscopy is used to measure actin flow and engagement. Analysis tools that allow for precise interrogation of clustering in pointillist SLM data and flow/engagement in intensity based TIRF data were developed concomitantly. Using these tools, it is apparent that integrin based “nano-adhesions” adopt regionally specific nanoclustering patterns upon cell migration, becoming smaller and denser in the focal zone/lamella as compared to the leading edge/lamellipodia. Nano-adhesion re-organisation is coupled to > 70% cortical actin engagement, with a degree of slippage where retrograde flow speed is always greater than cell speed. T cell migration can be slowed by use of cations or actin inhibitors, or sped by dosing with chemokines or deleting PTPN22. Upon migration speed increase, integrin nano-adhesions become larger in the cell membrane and reduce their engagement with actin. PTPN22 deficient cells also display an increase in the nanoscale colocalization of LFA-1 with pY397 FAK and pY416 Src family kinases, which occur in adhesions smaller than nascent adhesions in non-leukocytes. The local control of integrin LFA-1 nano-adhesions in migrating T cells is a new area of research that will improve our base framework for understanding immune cell migration, which may contribute to better understanding of migration defects that lead to autoimmune disease.
Date of Award2017
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorGeorgina Cornish (Supervisor), Andrew Cope (Supervisor) & Dylan Owen (Supervisor)

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