title: KCa3.1 and TRPM7 channels at the uropod regulate migration of activated human T cells.
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 ∼6 µm/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.
authors.affiliation: Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, United States of America.
authors.forename: Zerrin
authors.initials: Z
authors.lastname: Kuras
authors.forename: Yeo-Heung
authors.initials: YH
authors.lastname: Yun
authors.forename: Ameet A
authors.initials: AA
authors.lastname: Chimote
authors.forename: Lisa
authors.initials: L
authors.lastname: Neumeier
authors.forename: Laura
authors.initials: L
authors.lastname: Conforti
mesh_terms: D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D002465:Cell Movement; D022081:Cell Surface Extensions / Q000378:metabolism*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism*; D042541:Intracellular Space / Q000378:metabolism; D008297:Male; D000071740:ORAI1 Protein; D017346:Protein Serine-Threonine Kinases; D021381:Protein Transport; D013601:T-Lymphocytes / Q000166:cytology* / Q000378:metabolism*; D050053:TRPM Cation Channels / Q000378:metabolism*
chemical_list: D015220:Calcium Channels; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; C496923:KCNN4 protein, human; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; D050053:TRPM Cation Channels; D018799:Intercellular Adhesion Molecule-1; D017346:Protein Serine-Threonine Kinases; C486583:TRPM7 protein, human; D002118:Calcium