title: Rap1 translates chemokine signals to integrin activation, cell polarization, and motility across vascular endothelium under flow.
abstract: Chemokines arrest circulating lymphocytes within the vasculature through the rapid up-regulation of leukocyte integrin adhesive activity, promoting subsequent lymphocyte transmigration. However, the key regulatory molecules regulating this process have remained elusive. Here, we demonstrate that Rap1 plays a pivotal role in chemokine-induced integrin activation and migration. Rap1 was activated by secondary lymphoid tissue chemokine (SLC; CCL21) and stromal-derived factor 1 (CXCL4) treatment in lymphocytes within seconds. Inhibition of Rap1 by Spa1, a Rap1-specific GTPase-activating protein, abrogated chemokine-stimulated lymphocyte rapid adhesion to endothelial cells under flow via intercellular adhesion molecule 1. Expression of a dominant active Rap1V12 in lymphocytes stimulated shear-resistant adhesion, robust cell migration on immobilized intercellular adhesion molecule 1 and vascular cell adhesion molecule 1, and transendothelial migration under flow. We also demonstrated that Rap1V12 expression in lymphocytes induced a polarized morphology, accompanied by the redistribution of CXCR4 and CD44 to the leading edge and uropod, respectively. Spa1 effectively suppressed this polarization after SLC treatment. This unique characteristic of Rap1 may control chemokine-induced lymphocyte extravasation.
authors.affiliation: Bayer-chair, Dept. of Molecular Immunology and Allergy, Graduate School of Medicine, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Shimonaka
authors.forename: Koko
authors.initials: K
authors.lastname: Katagiri
authors.forename: Toshinori
authors.initials: T
authors.lastname: Nakayama
authors.forename: Naoya
authors.initials: N
authors.lastname: Fujita
authors.forename: Takashi
authors.initials: T
authors.lastname: Tsuruo
authors.forename: Osamu
authors.initials: O
authors.lastname: Yoshie
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kinashi
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D016764:Cell Polarity / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D054421:Chemokine CCL21; D054377:Chemokine CXCL12; D018925:Chemokines / Q000378:metabolism*; D019742:Chemokines, CC / Q000378:metabolism / Q000494:pharmacology; D019743:Chemokines, CXC / Q000378:metabolism / Q000494:pharmacology; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000502:physiology*; D004730:Endothelium, Vascular / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D018960:Hyaluronan Receptors / Q000235:genetics / Q000378:metabolism; D016023:Integrins / Q000378:metabolism*; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D009687:Nuclear Proteins / Q000378:metabolism / Q000494:pharmacology; D019718:Receptors, CXCR4 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D020827:rap1 GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: C515479:Ccl21c protein, mouse; D054421:Chemokine CCL21; D054377:Chemokine CXCL12; D018925:Chemokines; D019742:Chemokines, CC; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D020690:GTPase-Activating Proteins; D018960:Hyaluronan Receptors; D016023:Integrins; D016169:Lymphocyte Function-Associated Antigen-1; D009687:Nuclear Proteins; D019718:Receptors, CXCR4; C091108:Sipa1 protein, mouse; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; D020827:rap1 GTP-Binding Proteins