Talin-1 determines the direction of primary mouse neutrophils migrating in vivo 2223401

Abstract Introduction Neutrophils rely on β2 integrins, mainly LFA-1 and Mac-1, to mediate rolling, arrest, spreading and transmigration at inflamed sites. β2 integrins activation requires talin-1 binding to the cytoplasmic tail, yet the timing and localization of talin-1 recruitment and its distribution in vivo remain unclear. Methods To address this, we generated EGFP-talin1 (EGFP-talin1/EGFP-talin1) knock-in mice that enable real-time visualization of endogenous talin-1. EGFP-talin1 was expressed in neutrophils and supported β2 integrin activation without altering integrin surface expression or hematopoiesis. Results Using total internal reflection fluorescence microscopy showed that talin-1 was recruited to the plasma membrane during rolling and increased after arrest. Intravital imaging revealed that redistribution of talin-1 to endothelial contacts during luminal crawling and to the leading edge during transendothelial migration. After transendothelial migration, talin-1 polarized to the front and accumulated at emerging lamellipodia during the interstitial migration and before directional turning. Conclusion These results define the spatiotemporal dynamics of talin-1 during neutrophil recruitment and highlight talin-1 polarization as a key regulator of migratory directionality in vivo. Funding Source Supported by NHLBI, NIH (P01HL151433, Ginsberg PPG). Topic Categories Cellular Adhesion, Migration, and Inflammation (CAM)