title: Rapid up-regulation of alpha4 integrin-mediated leukocyte adhesion by transforming growth factor-beta1.
abstract: The alpha4 integrins (alpha4beta1 and alpha4beta7) are cell surface heterodimers expressed mostly on leukocytes that mediate cell-cell and cell-extracellular matrix adhesion. A characteristic feature of alpha4 integrins is that their adhesive activity can be subjected to rapid modulation during the process of cell migration. Herein, we show that transforming growth factor-beta1 (TGF-beta1) rapidly (0.5-5 min) and transiently up-regulated alpha4 integrin-dependent adhesion of different human leukocyte cell lines and human peripheral blood lymphocytes (PBLs) to their ligands vascular cell adhesion molecule-1 (VCAM-1) and connecting segment-1/fibronectin. In addition, TGF-beta1 enhanced the alpha4 integrin-mediated adhesion of PBLs to tumor necrosis factor-alpha-treated human umbilical vein endothelial cells, indicating the stimulation of alpha4beta1/VCAM-1 interaction. Although TGF-beta1 rapidly activated the small GTPase RhoA and the p38 mitogen-activated protein kinase, enhanced adhesion did not require activation of both signaling molecules. Instead, polymerization of actin cytoskeleton triggered by TGF-beta1 was necessary for alpha4 integrin-dependent up-regulated adhesion, and elevation of intracellular cAMP opposed this up-regulation. Moreover, TGF-beta1 further increased cell adhesion mediated by alpha4 integrins in response to the chemokine stromal cell-derived factor-1alpha. These data suggest that TGF-beta1 can potentially contribute to cell migration by dynamically regulating cell adhesion mediated by alpha4 integrins.
authors.affiliation: Department of Immunology, Centro de Investigaciones Biológicas, Madrid, 28006 Spain.
authors.forename: Rubén A
authors.initials: RA
authors.lastname: Bartolomé
authors.forename: Francisco
authors.initials: F
authors.lastname: Sanz-Rodríguez
authors.forename: Mar M
authors.initials: MM
authors.lastname: Robledo
authors.forename: Andrés
authors.initials: A
authors.lastname: Hidalgo
authors.forename: Joaquin
authors.initials: J
authors.lastname: Teixidó
mesh_terms: D000199:Actins / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology*; D006801:Humans; D039441:Integrin alpha4 / Q000378:metabolism*; D007962:Leukocytes / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D053773:Transforming Growth Factor beta1; D015854:Up-Regulation / Q000502:physiology; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000199:Actins; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D039441:Integrin alpha4; D020741:rho GTP-Binding Proteins