Publication details

Authors: Kuras, Z.; Yun, Y. H.; Chimote, A. A.; Neumeier, L.; Conforti, L. 
Title: KCa3.1 and TRPM7 channels at the uropod regulate migration of activated human T cells 
Type: Journal Article 
Publisher: PLoS One 
Year: 2012 
Start Page: e43859 
End Page:  
DOI: 10.1371/journal.pone.0043859 
Abstract: The migration of T lymphocytes is an essential part of the adaptive immune response as T cells circulate around the body to carry out immune surveillance. During the migration process T cells polarize, forming a leading edge at the cell front and a uropod at the cell rear. Our interest was in studying the involvement of ion channels in the migration of activated human T lymphocytes as they modulate intracellular Ca(2+) levels. Ca(2+) is a key regulator of cellular motility. To this purpose, we created protein surfaces made of the bio-polymer PNMP and coated with ICAM-1, ligand of LFA-1. The LFA-1 and ICAM-1 interaction facilitates T cell movement from blood into tissues and it is critical in immune surveillance and inflammation. Activated human T lymphocytes polarized and migrated on ICAM-1 surfaces by random walk with a mean velocity of approximately 6 microm/min. Confocal microscopy indicated that Kv1.3, CRAC, and TRPM4 channels positioned in the leading-edge, whereas KCa3.1 and TRPM7 channels accumulated in the uropod. The localization of KCa3.1 and TRPM7 at the uropod was associated with oscillations in intracellular Ca(2+) levels that we measured in this cell compartment. Further studies with blockers against Kv1.3 (ShK), KCa3.1 (TRAM-34), CRAC (SKF-96365), TRPM7 (2-APB), and TRPM4 (glibenclamide) indicated that blockade of KCa3.1 and TRPM7, and not Kv1.3, CRAC or TRPM4, inhibits the T cell migration. The involvement of TRPM7 in cell migration was confirmed with siRNAs against TRPM7. Downregulation of TRPM7 significantly reduced the number of migrating T cells and the mean velocity of the migrating T cells. These results indicate that KCa3.1 and TRPM7 selectively localize at the uropod of migrating T lymphocytes and are key components of the T cell migration machinery. 
Keywords: Calcium/metabolism, Calcium Channels/metabolism, *Cell Movement, Cell Surface Extensions/*metabolism, Humans, Intercellular Adhesion Molecule-1/metabolism, Intermediate-Conductance Calcium-Activated Potassium Channels/*metabolism, Intracellular Space/metabolism, Male, Protein Transport, T-Lymphocytes/*cytology/*metabolism, TRPM Cation Channels/*metabolism