Rapid increase in transferrin receptor recycling promotes adhesion during T cell activation.

Background: T cell activation leads to increased expression of the receptor for the iron transporter transferrin (TfR) to provide iron required for the cell differentiation and clonal expansion that takes place during the days after encounter with a cognate antigen. However, T cells mobilise TfR to their surface within minutes after activation, although the reason and mechanism driving this process remain unclear.

Results: Here we show that T cells transiently increase endocytic uptake and recycling of TfR upon activation, thereby boosting their capacity to import iron.

Cdc42 Couples T Cell Receptor Endocytosis to GRAF1-Mediated Tubular Invaginations of the Plasma Membrane.

T cell activation is immediately followed by internalization of the T cell receptor (TCR). TCR endocytosis is required for T cell activation, but the mechanisms supporting removal of TCR from the cell surface remain incompletely understood. Here we report that TCR endocytosis is linked to the clathrin-independent carrier (CLIC) and GPI-enriched endocytic compartments (GEEC) endocytic pathway.