title: An integrin alpha4beta7•IgG heterodimeric chimera binds to MAdCAM-1 on high endothelial venules in gut-associated lymphoid tissue.
abstract: Lymphocyte homing is regulated by a multistep process mediated by sequential adhesive interactions between circulating lymphocytes and high endothelial venules (HEVs). In gut-associated lymphoid tissue (GALT), the initial interactive step, "tethering and rolling," is partly mediated by integrin α4β7 expressed on GALT-homing lymphocytes and its ligand MAdCAM-1, which is exclusively expressed on HEVs in GALT. To probe functional MAdCAM-1 in tissue sections, we developed a soluble integrin α4β7 heterodimeric IgG chimera by joining the extracellular region of mouse integrin α4 and β7 subunits to a human IgG Fc domain. Western blot analysis revealed that co-transfection of HEK 293T cells with expression vectors encoding integrin α4•IgG and β7•IgG results in the formation of α4β7•IgG heterodimeric chimeras. This complex preferentially binds to CHO cells expressing MAdCAM-1 and, to a lesser extent, to cells expressing VCAM-1, but not to cells expressing ICAM-1. Moreover, α4β7•IgG specifically binds to HEVs in GALT in situ in a divalent cation-dependent fashion and inhibits lymphocyte binding to HEVs in GALT. These findings indicate that α4β7•IgG can be used as a probe for functional MAdCAM-1 expressed on HEVs in GALT and could potentially serve as an anti-inflammatory drug inhibiting GALT-specific lymphocyte migration.
authors: Department of Molecular Pathology, Shinshu University Graduate School of Medicine, Matsumoto, Nagano, Japan.
authors: Hitomi
authors: H
authors: Hoshino
authors: Motohiro
authors: M
authors: Kobayashi
authors: Junya
authors: J
authors: Mitoma
authors: Yoshiko
authors: Y
authors: Sato
authors: Minoru
authors: M
authors: Fukuda
authors: Jun
authors: J
authors: Nakayama
mesh_terms: D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D016466:CHO Cells; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D017931:DNA Primers; D019281:Dimerization; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D007136:Immunoglobulins / Q000378:metabolism*; D016023:Integrins / Q000378:metabolism*; D008221:Lymphoid Tissue / Q000098:blood supply / Q000378:metabolism*; D051379:Mice; D009088:Mucoproteins / Q000378:metabolism*; D014699:Venules / Q000378:metabolism*
chemical_list: D015815:Cell Adhesion Molecules; D017931:DNA Primers; D007074:Immunoglobulin G; D007136:Immunoglobulins; D016023:Integrins; C504265:MADCAM1 protein, human; C489082:Madcam1 protein, mouse; D009088:Mucoproteins; C071777:integrin alpha4beta7