title: A central role for DOCK2 during interstitial lymphocyte motility and sphingosine-1-phosphate-mediated egress.
abstract: Recent observations using multiphoton intravital microscopy (MP-IVM) have uncovered an unexpectedly high lymphocyte motility within peripheral lymph nodes (PLNs). Lymphocyte-expressed intracellular signaling molecules governing interstitial movement remain largely unknown. Here, we used MP-IVM of murine PLNs to examine interstitial motility of lymphocytes lacking the Rac guanine exchange factor DOCK2 and phosphoinositide-3-kinase (PI3K)gamma, signaling molecules that act downstream of G protein-coupled receptors, including chemokine receptors (CKRs). T and B cells lacking DOCK2 alone or DOCK2 and PI3Kgamma displayed markedly reduced motility inside T cell area and B cell follicle, respectively. Lack of PI3Kgamma alone had no effect on migration velocity but resulted in increased turning angles of T cells. As lymphocyte egress from PLNs requires the sphingosine-1-phosphate (S1P) receptor 1, a G(alphai) protein-coupled receptor similar to CKR, we further analyzed whether DOCK2 and PI3Kgamma contributed to S1P-triggered signaling events. S1P-induced cell migration was significantly reduced in T and B cells lacking DOCK2, whereas T cell-expressed PI3Kgamma contributed to F-actin polymerization and protein kinase B phosphorylation but not migration. These findings correlated with delayed lymphocyte egress from PLNs in the absence of DOCK2 but not PI3Kgamma, and a markedly reduced cell motility of DOCK2-deficient T cells in close proximity to efferent lymphatic vessels. In summary, our data support a central role for DOCK2, and to a lesser extent T cell-expressed PI3Kgamma, for signal transduction during interstitial lymphocyte migration and S1P-mediated egress.
authors.affiliation: Theodor Kocher Institute, University of Bern, CH-3012 Bern, Switzerland.
authors.forename: César
authors.initials: C
authors.lastname: Nombela-Arrieta
authors.forename: Thorsten R
authors.initials: TR
authors.lastname: Mempel
authors.forename: Silvia F
authors.initials: SF
authors.lastname: Soriano
authors.forename: Irina
authors.initials: I
authors.lastname: Mazo
authors.forename: Matthias P
authors.initials: MP
authors.lastname: Wymann
authors.forename: Emilio
authors.initials: E
authors.lastname: Hirsch
authors.forename: Carlos
authors.initials: C
authors.lastname: Martínez-A
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Fukui
authors.forename: Ulrich H
authors.initials: UH
authors.lastname: von Andrian
authors.forename: Jens V
authors.initials: JV
authors.lastname: Stein
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000235:genetics / Q000276:immunology; D002465:Cell Movement / Q000276:immunology*; D058544:Class Ib Phosphatidylinositol 3-Kinase; D020690:GTPase-Activating Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D020662:Guanine Nucleotide Exchange Factors; D007527:Isoenzymes / Q000172:deficiency / Q000235:genetics; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D008214:Lymphocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D008246:Lysophospholipids / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019869:Phosphatidylinositol 3-Kinases / Q000172:deficiency / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000502:physiology
chemical_list: D058544:Class Ib Phosphatidylinositol 3-Kinase; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D007527:Isoenzymes; D008246:Lysophospholipids; D019869:Phosphatidylinositol 3-Kinases; D013110:Sphingosine; C471356:DOCK2 protein, mouse; C060506:sphingosine 1-phosphate; C546764:Pik3cg protein, mouse