Activated integrin VLA-4 localizes to the lamellipodia and mediates T cell migration on VCAM-1.
Lymphocyte migration from blood into lymphoid tissues or to sites of inflammation occurs through interactions between cell surface integrins and their ligands expressed on the vascular endothelium and the extracellular matrix. VLA-4 (alpha(4)beta(1)) is a key integrin in the effective trafficking of lymphocytes. Although it has been well established that integrins undergo functionally significant conformational changes to mediate cell adhesion, there is no mechanistic information that explains how these are dynamically and spatially regulated during lymphocyte polarization and migration. Using dynamic fluorescence resonance energy transfer analysis of a novel VLA-4 FRET sensor under total internal reflection fluorescence microscopy, we show that VLA-4 activation localizes to the lamellipodium in living cells. During T cell migration on VCAM-1, VLA-4 activation concurs with spatial redistribution of chemokine receptor and active Rap1 at the leading edge. Selective inhibition of the activated VLA-4 at the leading edge with a small molecule inhibitor is sufficient to block T cell migration. These data suggest that a subpopulation of activated VLA-4 is mainly localized to the leading edge of polarized human T cells and is critical for T cell migration on VCAM-1.
Hyun
Young-Min
YM
Department of Microbiology and Immunology, David H. Smith Center for Vaccine Biology and Immunology, University of Rochester, NY 14642, USA.
Chung
Hung-Li
HL
McGrath
James L
JL
Waugh
Richard E
RE
Kim
Minsoo
M
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002464:Cell Migration Inhibition / Q000235:genetics / Q000276:immunology; D002465:Cell Movement / Q000235:genetics / Q000276:immunology*; D016764:Cell Polarity / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D039041:Integrin alpha4beta1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011554:Pseudopodia / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
D039041:Integrin alpha4beta1; D019010:Vascular Cell Adhesion Molecule-1