Abstract
Dendritic cells (DCs) are professional antigen (Ag)-presenting cells that excel in initiating adaptive immune responses by continuously scanning peripheral tissues for Ags. To facilitate efficient DC migration, constant cross-talk between actin and microtubules is required to coordinate cytoskeletal networks and actomyosin contractility, but the related mechanisms have not been extensively characterized. We show that mouse DCs lacking Kif5b (the heavy chain of kinesin-1) exhibit a major impairment in cell migration in vivo and in vitro. Mechanistically, kinesin-1 coordinates cytoskeletal cross-talk between actin and microtubules during DC migration by modulating negatively RhoA activity through its interaction with GEF-H1, thereby limiting GEF-H1's availability in the cytosol. The same mechanism operates in human primary monocyte-derived DCs and regulates efficient migration in a confined environment. Thus, our results highlight kinesin-1 as a key regulator of DC migration, through its coordinated control of cytoskeletal dynamics.