title: Human vascular adhesion protein-1 in smooth muscle cells.
abstract: Human vascular adhesion protein-1 (VAP-1) is a dual-function molecule with adhesive and enzymatic properties. In addition to synthesis in endothelial cells, where it mediates lymphocyte binding, VAP-1 is expressed in smooth muscle cells. Here we studied the expression, biochemical structure, and function of VAP-1 in muscle cells and compared it to those in endothelial cells. VAP-1 is expressed on the plasma membrane of all types of smooth muscle cells, but it is completely absent from cardiac and skeletal muscle cells. In tumors, VAP-1 is retained on all leiomyoma cells, whereas it is lost in half of leiomyosarcoma samples. In smooth muscle VAP-1 predominantly exists as a approximately 165-kd homodimeric glycoprotein, but a trimeric (approximately 250 kd) form of VAP-1 is also found. It contains N-linked oligosaccharide side chains and abundant sialic acid decorations. In comparison, in endothelial cells dimeric VAP-1 is larger, no trimeric forms are found, and VAP-1 does not have N-glycanase-sensitive oligosaccharides. Unlike endothelial VAP-1, VAP-1 localized on smooth muscle cells does not support binding of lymphocytes. Instead, it deaminates exogenous and endogenous primary amines. In conclusion, VAP-1 in smooth muscle cells is structurally and functionally distinct from VAP-1 present on endothelial cells.
authors.affiliation: National Public Health Institute and MediCity Research Laboratory, University of Turku, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Jaakkola
authors.forename: K
authors.initials: K
authors.lastname: Kaunismäki
authors.forename: S
authors.initials: S
authors.lastname: Tohka
authors.forename: G
authors.initials: G
authors.lastname: Yegutkin
authors.forename: E
authors.initials: E
authors.lastname: Vänttinen
authors.forename: T
authors.initials: T
authors.lastname: Havia
authors.forename: L J
authors.initials: LJ
authors.lastname: Pelliniemi
authors.forename: M
authors.initials: M
authors.lastname: Virolainen
authors.forename: S
authors.initials: S
authors.lastname: Jalkanen
authors.forename: M
authors.initials: M
authors.lastname: Salmi
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000032:analysis / Q000378:metabolism* / Q000502:physiology; D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules / Q000032:analysis / Q000378:metabolism* / Q000502:physiology; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D015536:Down-Regulation; D004727:Endothelium / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D007890:Leiomyosarcoma / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism; D016253:Microscopy, Immunoelectron; D008995:Monoamine Oxidase / Q000378:metabolism; D009130:Muscle, Smooth / Q000378:metabolism* / Q000473:pathology*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000473:pathology; D012795:Sialoglycoproteins; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules; D012795:Sialoglycoproteins; C076668:AOC3 protein, human; D006631:Amine Oxidase (Copper-Containing); D008995:Monoamine Oxidase; D006026:Glycoside Hydrolases