Casein kinase I delta controls centrosome positioning during T cell activation.

Although termed central body, the centrosome is located off-center in many polarized cells. T cell receptor (TCR) engagement by antigens induces a polarity switch in T cells. This leads to the recruitment of the centrosome to the immunological synapse (IS), a specialized cell--cell junction. Despite much recent progress, how TCR signaling triggers centrosome repositioning remains poorly understood. In this paper, we uncover a critical requirement for the centrosomal casein kinase I delta (CKId) in centrosome translocation to the IS. CKId binds and phosphorylates the microtubule plus-end--binding protein EB1. Moreover, a putative EB1-binding motif at the C terminus of CKId is required for centrosome translocation to the IS. We find that depletion of CKId in T lymphocytes and inhibition of CKI in epithelial cells reduce microtubule growth. Therefore, we propose that CKId--EB1 complexes contribute to the increase in microtubule growth speeds observed in polarized T cells, a mechanism that might serve to generate long-stable microtubules necessary for centrosome translocation. [ABSTRACT FROM AUTHOR]