
pmid: 17023430
Integrin-mediated adhesion is a crucial step in lymphocyte extravasation and homing. We show here that not only the chemokines CXCL12 and CXCL13 but also the lysophospholipids sphingosine 1-phosphate (S1P) and lysophosphatidic acid (LPA) enhance adhesion of murine follicular and marginal zone B cells to ICAM-1 in vitro. This process involves clustering of integrin LFA-1 and is blocked by pertussis toxin, suggesting that G(i) family G-proteins are involved. In addition, lysophospholipid-induced adhesion on ICAM-1 depends on Rho and Rhokinase, indicative of an involvement of G(12)/G(13), possibly also G(q)/G(11) family G-proteins. We used G(12)/G(13)- or G(q)/G(11)-deficient B cells to study the role of these G-protein families in lysophospholipid-induced adhesion and found that the pro-adhesive effects of LPA and S1P are completely abrogated in G(12)/G(13)-deficient marginal zone B cells, reduced in G(12)/G(13)-deficient follicular B cells, and normal in G(q)/G(11)-deficient B cells. We also show that loss of lysophospholipid-induced adhesion results in disinhibition of migration in response to the follicular chemokine CXCL13, which might contribute to the abnormal localization of splenic B cell populations observed in B cell-specific G(12)/G(13)-deficient mice in vivo. Taken together, this study shows that lysophospholipids regulate integrin-mediated adhesion of splenic B cells to ICAM-1 through G(i) and G(12)/G(13) family G-proteins but not through G(q)/G(11).
rho GTP-Binding Proteins, B-Lymphocytes, Integrins, rho-Associated Kinases, Intracellular Signaling Peptides and Proteins, Protein Serine-Threonine Kinases, Intercellular Adhesion Molecule-1, GTP-Binding Protein alpha Subunits, G12-G13, Mice, Inbred C57BL, Mice, GTP-Binding Proteins, Sphingosine, Cell Adhesion, Animals, GTP-Binding Protein alpha Subunits, Gq-G11, Lysophospholipids, Spleen
rho GTP-Binding Proteins, B-Lymphocytes, Integrins, rho-Associated Kinases, Intracellular Signaling Peptides and Proteins, Protein Serine-Threonine Kinases, Intercellular Adhesion Molecule-1, GTP-Binding Protein alpha Subunits, G12-G13, Mice, Inbred C57BL, Mice, GTP-Binding Proteins, Sphingosine, Cell Adhesion, Animals, GTP-Binding Protein alpha Subunits, Gq-G11, Lysophospholipids, Spleen
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