Differential nanoscale organisation of LFA-1 modulates T cell migration

Abstract

Effector T-cells rely on integrins to drive adhesion and migration to facilitate their immune function. Heterodimeric transmembrane integrin LFA-1 (αLβ2) regulates adhesion and migration through linkage of the extracellular matrix with the intracellular actin treadmill machinery. We quantitated the velocity and direction of F-actin flow in migrating T-cells alongside single molecule localisation of transmembrane and intracellular LFA-1. Our results show that retrograde actin flow positively correlated and immobile actin negatively correlated with T-cell velocity. Plasma membrane localised LFA-1 forms unique nano-clustering patterns in the leading edge, compared to the mid-focal zone, in migrating T-cells. Deleting the cytosolic phosphatase PTPN22, a negative regulator of integrin signaling, increased T-cell velocity, and leading-edge cluster co-localisation of pY397 FAK, pY416 Src family kinases and LFA-1. These data suggest that differential nanoclustering patterns of LFA-1 in migrating T-cells can instruct intracellular signalling linked with the actin treadmill. Our data presents a paradigm where T cells modulate the nanoscale organisation of adhesion and signalling molecules to fine tune their migration speed. This has implications for the regulation of immune and inflammatory responses. ResultsThe speed of actin retrograde flow is positively correlated with T-cell velocity and negatively correlated with immobile actin.

LFA-1 in T cell priming, differentiation, and effector functions

“…Kindlin-3 [134,135], FAK [136,137], Pyk [136] and other cytoskeletal regulators, eventually leading to RhoA and Rac1 activation [133,138,139] and further actin remodeling. Recently, one study [140] reported that CD4 + T cells from Crk-L and Crk double knockout mice were spreading less efficiently on surfaces coated with the LFA-1 substrate ICAM-1 and displayed less actin staining at the cell surface than wildtype CD4 + T cells, indicative of impaired actin polymerization.…”

The Role of Protein and Lipid Clustering in Lymphocyte Activation

“…It was found that the mutation, in a non-catalytic protein binding domain, alters the clustering profile of PTPN22 with a resulting failure to de-cluster upon cell stimulation. The R620W mutation was also shown to be associated with changes in LFA-1 integrin clustering in migrating T cells (46).…”