Limits...
Rap1 translates chemokine signals to integrin activation, cell polarization, and motility across vascular endothelium under flow.

Shimonaka M, Katagiri K, Nakayama T, Fujita N, Tsuruo T, Yoshie O, Kinashi T - J. Cell Biol. (2003)

Bottom Line: 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.Spa1 effectively suppressed this polarization after SLC treatment.

View Article: PubMed Central - PubMed

Affiliation: Bayer-chair, Dept. of Molecular Immunology and Allergy, Graduate School of Medicine, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan.

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.

Show MeSH

Related in: MedlinePlus

Polarized morphology and membrane protein redistribution induced by SDF-1 and Rap1V12. Rap1V12- or Spa-1–expressing BAF/LFA-1 cells stimulated with or without 100 nM SDF-1 for 10 min, as indicated, were fixed in suspension and stained for CXCR4 (green) and CD44 (red), as described in Materials and methods. Bars, 10 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2172897&req=5

fig8: Polarized morphology and membrane protein redistribution induced by SDF-1 and Rap1V12. Rap1V12- or Spa-1–expressing BAF/LFA-1 cells stimulated with or without 100 nM SDF-1 for 10 min, as indicated, were fixed in suspension and stained for CXCR4 (green) and CD44 (red), as described in Materials and methods. Bars, 10 μm.

Mentions: Chemokines induce a polarized cell morphology and induce the redistribution of chemokine receptors to the leading edge (Nieto et al., 1997; Gomez-Mouton et al., 2001) and intercellular adhesion molecules, including CD44 (del Pozo et al., 1995), to the uropod. As leukocyte polarization plays an important role in rapid directional movement, we examined the effect of Rap1 activation on this process. Rap1V12 expressing BAF/LFA-1 cells, fixed in suspension, demonstrated a polarized cell shape with a morphologically-defined leading edge and a uropod; control cells were round in shape (Fig. 8) . The polarized cell shape was examined with CXCR4 and CD44, leading edge and uropod markers, respectively. Compared with homogenous or intermingled distribution in nonpolarized control cells, CXCR4 and CD44 were segregated, concentrating at the leading edge and uropod, respectively. A similar polarization phenotype concurrent with the redistribution of cell surface receptors was also seen on stimulation with SDF-1 (Fig. 8). Spa1 expression completely suppressed the polarized phenotype induced by SDF-1. These results suggest that Rap1 activation by chemokines induces cell polarization.


Rap1 translates chemokine signals to integrin activation, cell polarization, and motility across vascular endothelium under flow.

Shimonaka M, Katagiri K, Nakayama T, Fujita N, Tsuruo T, Yoshie O, Kinashi T - J. Cell Biol. (2003)

Polarized morphology and membrane protein redistribution induced by SDF-1 and Rap1V12. Rap1V12- or Spa-1–expressing BAF/LFA-1 cells stimulated with or without 100 nM SDF-1 for 10 min, as indicated, were fixed in suspension and stained for CXCR4 (green) and CD44 (red), as described in Materials and methods. Bars, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172897&req=5

fig8: Polarized morphology and membrane protein redistribution induced by SDF-1 and Rap1V12. Rap1V12- or Spa-1–expressing BAF/LFA-1 cells stimulated with or without 100 nM SDF-1 for 10 min, as indicated, were fixed in suspension and stained for CXCR4 (green) and CD44 (red), as described in Materials and methods. Bars, 10 μm.
Mentions: Chemokines induce a polarized cell morphology and induce the redistribution of chemokine receptors to the leading edge (Nieto et al., 1997; Gomez-Mouton et al., 2001) and intercellular adhesion molecules, including CD44 (del Pozo et al., 1995), to the uropod. As leukocyte polarization plays an important role in rapid directional movement, we examined the effect of Rap1 activation on this process. Rap1V12 expressing BAF/LFA-1 cells, fixed in suspension, demonstrated a polarized cell shape with a morphologically-defined leading edge and a uropod; control cells were round in shape (Fig. 8) . The polarized cell shape was examined with CXCR4 and CD44, leading edge and uropod markers, respectively. Compared with homogenous or intermingled distribution in nonpolarized control cells, CXCR4 and CD44 were segregated, concentrating at the leading edge and uropod, respectively. A similar polarization phenotype concurrent with the redistribution of cell surface receptors was also seen on stimulation with SDF-1 (Fig. 8). Spa1 expression completely suppressed the polarized phenotype induced by SDF-1. These results suggest that Rap1 activation by chemokines induces cell polarization.

Bottom Line: 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.Spa1 effectively suppressed this polarization after SLC treatment.

View Article: PubMed Central - PubMed

Affiliation: Bayer-chair, Dept. of Molecular Immunology and Allergy, Graduate School of Medicine, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan.

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.

Show MeSH
Related in: MedlinePlus