KCa3.1 and TRPM7 channels at the uropod regulate migration of activated human T cells

PLoS One. 2012;7(8):e43859. doi: 10.1371/journal.pone.0043859. Epub 2012 Aug 27.

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • 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
  • ORAI1 Protein
  • Protein Transport
  • Protein-Serine-Threonine Kinases
  • T-Lymphocytes / cytology*
  • T-Lymphocytes / metabolism*
  • TRPM Cation Channels / metabolism*

Substances

  • Calcium Channels
  • Intermediate-Conductance Calcium-Activated Potassium Channels
  • KCNN4 protein, human
  • ORAI1 Protein
  • ORAI1 protein, human
  • TRPM Cation Channels
  • Intercellular Adhesion Molecule-1
  • Protein-Serine-Threonine Kinases
  • TRPM7 protein, human
  • Calcium