%0 Journal Article
%T Vascular Adhesion Protein 1 in the Eye
%A Wenting Luo
%A Fang Xie
%A Zhongyu Zhang
%A Dawei Sun
%J Journal of Ophthalmology
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/925267
%X Semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 (SSAO/VAP-1), a dual-function molecule with adhesive and enzymatic properties, is expressed on the surface of vascular endothelial cells of mammals. It also exists as a soluble form (sVAP-1), which is implicated in oxidative stress via its enzymatic activity and can be a prognostic biomarker. Recent evidence suggests that VAP-1 is an important therapeutic target for several inflammation-related ocular diseases, such as uveitis, age-related macular degeneration (AMD), and diabetic retinopathy (DR), by involving in the recruitment of leukocytes at sites of inflammation. Furthermore, VAP-1 plays an important role in the pathogenesis of conjunctival inflammatory diseases such as pyogenic granulomas and the progression of conjunctival lymphoma. VAP-1 may be an alternative therapeutic target in ocular diseases. The in vivo imaging of inflammation using VAP-1 as a target molecule is a novel approach with a potential for early detection and characterization of inflammatory diseases. This paper reviews the critical roles of VAP-1 in ophthalmological diseases which may provide a novel research direction or a potent therapeutic strategy. 1. Introduction Vascular adhesion protein-1 (VAP-1) is a homodimeric sialylated glycoprotein originally discovered in inflamed synovial vessels by Salmi and Jalkanen in 1992 [1]. VAP-1 is a multifunctional molecule that possesses enzymatic activity known as semicarbazide-sensitive amine oxidase (SSAO) and is involved in the leukocyte recruitment cascade. The VAP-1 molecule consists of an extracellular part, which harbors the catalytic site, a transmembrane segment, and a short intracellular N-terminal tail [2, 3]. On the plasma membrane, VAP-1 normally forms a homodimer of two 90£¿kDa glycoproteins. The extracellular part of each monomer consists of three domains (D2¨CD4). VAP-1 has a relatively narrow substrate channel formed by domains D4 and D3, and a key leucine (469 in human) guards the entry of substrates. The large D4 domains, from each subunit, form the dimer interface and each also contains a catalytic site, buried at the base of a deep cleft. VAP-1 exists as membrane-bound and soluble forms in the plasma. Its major sources are endothelial cells, smooth muscle cells, and the adipocytes [4]. VAP-1 is expressed on the endothelium of human tissues such as skin, brain, lung, liver, and heart under both normal and inflamed conditions [4¨C8]. In the ocular tissues of humans and rats, VAP-1 is localized on the endothelial cells of retinal and choroidal vessels
%U http://www.hindawi.com/journals/joph/2013/925267/