Developing T-cell migration: role of semaphorins and ephrins

Cell migration is a crucial event for normal T-cell development, and various ligand/receptor pairs have been implicated. Most of them, including chemokines and extracellular matrix proteins, have attractant properties on thymocytes. We discuss herein two further groups of ligand/receptor pairs, semaphorins/neuropilins and ephs/ephrins, which are constitutively expressed by thymocytes and thymic microenvironmental cells. Evidence shows that the corresponding interactions are relevant for developing T-cell migration, including the entry of bone marrow progenitor cells, migration of CD4/CD8-defined thymocyte subpopulations triggered by chemokines and/or extracellular matrix proteins, and thymocyte export. Conceptually, the data summarized here show that thymocyte migration results from a complex network of molecular interactions, which generate not only attraction, but also repulsion of migrating T-cell precursors.-Mendes-da-Cruz, D. A., Stimamiglio, M. A., Munoz, J. J., Alfaro, D., Terra-Granado, E., Garcia-Ceca, J., Alonso-Colmenar, L. M., Savino, W., Zapata, A. G. Developing T-cell migration: role of semaphorins and ephrins. FASEB J. 26, 4390-4399 (2012). www.fasebj.org