title: Siglec-9 is a novel leukocyte ligand for vascular adhesion protein-1 and can be used in PET imaging of inflammation and cancer.
abstract: Leukocyte migration to sites of inflammation is regulated by several endothelial adhesion molecules. Vascular adhesion protein-1 (VAP-1) is unique among the homing-associated molecules as it is both an enzyme that oxidizes primary amines and an adhesin. Although granulocytes can bind to endothelium via a VAP-1-dependent manner, the counter-receptor(s) on this leukocyte population is(are) not known. Here we used a phage display approach and identified Siglec-9 as a candidate ligand on granulocytes. The binding between Siglec-9 and VAP-1 was confirmed by in vitro and ex vivo adhesion assays. The interaction sites between VAP-1 and Siglec-9 were identified by molecular modeling and confirmed by further binding assays with mutated proteins. Although the binding takes place in the enzymatic groove of VAP-1, it is only partially dependent on the enzymatic activity of VAP-1. In positron emission tomography, the ⁶⁸Gallium-labeled peptide of Siglec-9 specifically detected VAP-1 in vasculature at sites of inflammation and cancer. Thus, the peptide binding to the enzymatic groove of VAP-1 can be used for imaging conditions, such as inflammation and cancer.
authors.affiliation: MediCity Research Laboratory and Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.
authors.forename: Kristiina
authors.initials: K
authors.lastname: Aalto
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland.
authors.forename: Anu
authors.initials: A
authors.lastname: Autio
authors.affiliation: MediCity Research Laboratory and Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.
authors.forename: Elina A
authors.initials: EA
authors.lastname: Kiss
authors.affiliation: MediCity Research Laboratory and Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.|Department of Medical Biochemistry and Genetics, University of Turku, Turku, Finland.
authors.forename: Kati
authors.initials: K
authors.lastname: Elima
authors.affiliation: Structural Bioinformatics Laboratory, Department of Biosciences, Åbo Akademi University, Turku, Finland.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Nymalm
authors.affiliation: MediCity Research Laboratory and Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.
authors.forename: Tibor Z
authors.initials: TZ
authors.lastname: Veres
authors.affiliation: MediCity Research Laboratory and Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.
authors.forename: Fumiko
authors.initials: F
authors.lastname: Marttila-Ichihara
authors.affiliation: MediCity Research Laboratory and Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.
authors.forename: Heli
authors.initials: H
authors.lastname: Elovaara
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland.
authors.forename: Tiina
authors.initials: T
authors.lastname: Saanijoki
authors.affiliation: The Wellcome Trust Biocentre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, United Kingdom.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Crocker
authors.affiliation: MediCity Research Laboratory and Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.
authors.forename: Mikael
authors.initials: M
authors.lastname: Maksimow
authors.affiliation: Structural Bioinformatics Laboratory, Department of Biosciences, Åbo Akademi University, Turku, Finland.
authors.forename: Eva
authors.initials: E
authors.lastname: Bligt
authors.affiliation: Structural Bioinformatics Laboratory, Department of Biosciences, Åbo Akademi University, Turku, Finland.
authors.forename: Tiina A
authors.initials: TA
authors.lastname: Salminen
authors.affiliation: MediCity Research Laboratory and Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.|Department of Medical Biochemistry and Genetics, University of Turku, Turku, Finland.|National Institute of Public Health and Welfare, Turku, Finland.
authors.forename: Marko
authors.initials: M
authors.lastname: Salmi
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland.
authors.forename: Anne
authors.initials: A
authors.lastname: Roivainen
authors.affiliation: MediCity Research Laboratory and Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.|National Institute of Public Health and Welfare, Turku, Finland.
authors.forename: Sirpa
authors.initials: S
authors.lastname: Jalkanen
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D016466:CHO Cells; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D007249:Inflammation / Q000000981:diagnostic imaging*; D037102:Lectins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D008024:Ligands; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009369:Neoplasms / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography / Q000379:methods*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs / Q000502:physiology; D011849:Radioactive Tracers; D051381:Rats; D017207:Rats, Sprague-Dawley; D063265:Sialic Acid Binding Immunoglobulin-like Lectins
chemical_list: D015703:Antigens, CD; D015815:Cell Adhesion Molecules; D037102:Lectins; D008024:Ligands; D011849:Radioactive Tracers; C412227:SIGLEC9 protein, human; D063265:Sialic Acid Binding Immunoglobulin-like Lectins; C076668:AOC3 protein, human; D006631:Amine Oxidase (Copper-Containing)