title: Divalent cations regulate the organization of integrins alpha v beta 3 and alpha v beta 5 on the cell surface.
abstract: Extracellular divalent cations are important regulators of integrin ligand binding activity. In this study we evaluated how divalent cations affect the organization of integrins into focal adhesion sites. Integrins alpha v beta 3 and alpha v beta 5 were compared because they share a high degree of structural homology and because both integrins mediate cell adhesion to vitronectin. On MG-63 osteosarcoma cells, we found that both the extent and pattern of integrin organization was regulated by the type of extracellular divalent ion. Integrin alpha v beta 3 organized in focal contacts when Mn2+ or Mg2+ was present, but not in Ca2+. In contrast, alpha v beta 5 organized in focal contacts only when Ca2+ or Mg2+ was present. Integrin alpha v beta 5 clustered in a centrally located punctate field on the ventral surface of the cell in the presence of Mn2+. These observations reveal a previously unappreciated role for divalent ions in regulating the organization of integrins into focal adhesion sites.
authors.affiliation: Department of Molecular and Experimental Medicine and Vascular Biology, Scripps Research Institute, La Jolla, California, USA.
authors.forename: I
authors.initials: I
authors.lastname: Stuiver
authors.forename: Z
authors.initials: Z
authors.lastname: Ruggeri
authors.forename: J W
authors.initials: JW
authors.lastname: Smith
mesh_terms: D015703:Antigens, CD / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry; D002413:Cations, Divalent; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000737:chemistry*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D039482:Integrin alpha5; D039641:Integrin beta Chains; D039661:Integrin beta3; D016023:Integrins / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry; D008345:Manganese / Q000737:chemistry; D012516:Osteosarcoma; D010980:Platelet Membrane Glycoproteins / Q000737:chemistry*; D011940:Receptor Aggregation; D019030:Receptors, Vitronectin / Q000737:chemistry*; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D002413:Cations, Divalent; D015815:Cell Adhesion Molecules; D039482:Integrin alpha5; D039641:Integrin beta Chains; D039661:Integrin beta3; D016023:Integrins; D010980:Platelet Membrane Glycoproteins; D019030:Receptors, Vitronectin; C084344:integrin beta5; D008345:Manganese; D008274:Magnesium; D002118:Calcium