Talin-1 determines the direction of primary mouse neutrophils migrating in vivo

Talin-1 is essential for β2 integrin activation in neutrophils, yet its dynamic behavior during neutrophil trafficking in vivo remains poorly understood. Here, we generated EGFP-talin1 knock-in mice, enabling real-time visualization of talin-1 dynamics under physiological conditions. EGFP-talin1 is robustly expressed and preserves without altering β2 integrin expression and activation. Using total internal reflection fluorescence (TIRF) microscopy under flow, we found that talin-1 was rapidly recruited to the plasma membrane during rolling and accumulates further during neutrophil arrest. Intravital microscopy revealed highly dynamic and stage-specific talin-1 redistribution during luminal crawling, transendothelial migration, and interstitial migration. Talin-1 preferentially accumulated at endothelial contact sites during crawling and polarized toward the leading edge during directional migration. These findings establish EGFP-talin1 knock-in mice as platform for visualizing integrin-associated cytoskeletal dynamics in vivo and identify dynamic talin-1 polarization as a feature of neutrophil trafficking.