title: Orai1 function is essential for T cell homing to lymph nodes.
abstract: In T lymphocytes, Ca(2+) release-activated Ca(2+) (CRAC) channels composed of Orai1 subunits trigger Ag-induced gene expression and cell proliferation through the NFAT pathway. We evaluated the requirement of CRAC channel function for lymphocyte homing using expression of a dominant-negative Orai1-E106A mutant to suppress Ca(2+) signaling. To investigate homing and motility of human lymphocytes in immunocompromised mouse hosts, we transferred human lymphocytes either acutely or after stable engraftment after a second transfer from the same blood donor. Human and mouse lymphocyte homing was assessed, and cells were tracked within lymph nodes (LNs) by two-photon microscopy. Our results demonstrate that human T and B lymphocytes home into and migrate within the LNs of immunocompromised NOD.SCID mice similar to murine lymphocytes. Human T and B cells colocalized in atrophied or reconstituted mouse LNs, where T cells migrated in a random walk at velocities of 9-13 μm/min and B cells at 6 μm/min. Expression of Orai1-E106A inhibited CRAC channel function in human and mouse T cells, and prevented homing from high endothelial venules into murine LNs. Ca(2+) signals induced by CCL21 were also inhibited in T cells expressing Orai1-E106A. With CRAC channels inhibited, the high-affinity form of LFA-1 failed to become active, and T cells failed to migrate across endothelial cells in a transwell model. These results establish a requirement for CRAC channel-mediated Ca(2+) influx for T cell homing to LNs mediated by high-affinity integrin activation and chemokine-induced transendothelial migration.
authors: Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697, USA.
authors: Milton L
authors: ML
authors: Greenberg
authors: Ying
authors: Y
authors: Yu
authors: Sabrina
authors: S
authors: Leverrier
authors: Shenyuan L
authors: SL
authors: Zhang
authors: Ian
authors: I
authors: Parker
authors: Michael D
authors: MD
authors: Cahalan
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling; D002465:Cell Movement / Q000276:immunology; D058948:Cell Tracking; D054421:Chemokine CCL21 / Q000378:metabolism; D006801:Humans; D016867:Immunocompromised Host; D008198:Lymph Nodes / Q000276:immunology* / Q000378:metabolism*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009154:Mutation; D000071740:ORAI1 Protein; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*
chemical_list: D015220:Calcium Channels; D054421:Chemokine CCL21; D016169:Lymphocyte Function-Associated Antigen-1; D000071740:ORAI1 Protein; C520430:Orai1 protein, mouse