Talin-2 regulates integrin functions in exosomes.

Integrins on exosomes have been shown to mediate binding to recipient cells, potentially playing important roles in controlling exosomal internalization and organ distributions. Although the ability of cellular integrins to mediate cell adhesion is known to be regulated by the cytoplasmic adaptor protein talin, whether the activity of exosomal integrins is similarly regulated by talin remains to be elucidated. Here we have studied this question in T-cell exosomes that surface express the integrins αLβ2 and α4β7. T-cells and T-cell exosomes engineered to lack talin-2 showed reduced binding to the integrin ligand ICAM-1 and MAdCAM-1 compared with control T-cells and exosomes, despite the fact that those T cells and exosomes express intact levels of the other isoform talin-1. In addition, talin-2-deficient T-cell exosomes were less efficiently internalized by endothelial cells, compared with control exosomes. These results suggest that the mechanisms of talin-mediated integrin regulation operate similarly in cells and exosomes.