title: Fc-saxatilin suppresses hypoxia-induced vascular leakage by regulating endothelial occludin expression.
abstract: Vascular leakage due to compromised integrity of the endothelial barrier is closely associated with brain damage in several neurological disorders, including ischaemic stroke. Saxatilin, a snake venom disintegrin containing the Arg-Gly-Asp (RGD) motif, exerts thrombolytic and antiplatelet effects by interacting with multiple integrins on platelets. Integrin signalling is indispensable for regulation of endothelial permeability. Saxatilin may play a role in vascular leakage after ischaemia because it has high affinity for endothelial integrins. Here, we determined whether Fc-saxatilin, an Fc-fusion protein of saxatilin, could prevent vascular leakage under hypoxic or ischaemic conditions. In mouse brain microvascular endothelial cells, hypoxia increased the permeability to FITC-dextran, and this effect was attenuated by Fc-saxatilin treatment. Fc-saxatilin also blocked vascular leakage of Evans Blue in the ischaemic brain induced by middle cerebral artery occlusion in mice. Furthermore, the expression of occludin, a tight junction protein, was reduced by hypoxia in endothelial cells. This downregulation of occludin was attenuated by Fc-saxatilin treatment. We also determined the activity of matrix metalloproteinases (MMPs) 2 and 9 because they are implicated in the degradation of occludin and of the microvascular basal lamina. Hypoxia increased MMP-9 activity, and this increase was attenuated by Fc-saxatilin treatment. Fc-saxatilin specifically bound to integrin αvβ3of the endothelial cells and inhibited hypoxia-induced activation of FAK, a downstream signalling molecule in integrin-dependent signal transduction. Taken together, these results provide new insights into the mechanism via which Fc-saxatilin, as an integrin antagonist, prevents vascular leakage under ischemic conditions by regulating occludin expression in endothelial tight junctions.
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Choi
authors.forename: Il
authors.initials: I
authors.lastname: Kwon
authors.forename: Na-Eun
authors.initials: NE
authors.lastname: Kim
authors.forename: Jayoung
authors.initials: J
authors.lastname: Kim
authors.forename: Sunho
authors.initials: S
authors.lastname: An
authors.forename: Sungsoo
authors.initials: S
authors.lastname: Kang
authors.forename: Sung-Yu
authors.initials: SY
authors.lastname: Hong
authors.forename: Hyo Suk
authors.initials: HS
authors.lastname: Nam
authors.affiliation: Ji Hoe Heo, MD, PhD, Department of Neurology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 120-752, Republic of Korea, Tel.: +82 2 2228 1605, Fax: +82 2 2227 7906, E-mail: jhheo@yuhs.ac.
authors.forename: Ji Hoe
authors.initials: JH
authors.lastname: Heo
mesh_terms: D000818:Animals; D001921:Brain / Q000098:blood supply*; D002199:Capillary Permeability / Q000187:drug effects*; D015687:Cell Hypoxia; D002460:Cell Line; D019483:Disintegrins / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D002546:Ischemic Attack, Transient / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D055806:Microvessels / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D062793:Occludin / Q000378:metabolism*; D010766:Phosphorylation; D015427:Reperfusion Injury / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
chemical_list: D019483:Disintegrins; D039302:Integrin alphaVbeta3; C568985:OCLN protein, human; D062793:Occludin; C568986:Ocln protein, mouse; C459080:saxatilin; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; C496051:Ptk2 protein, mouse; D020778:Matrix Metalloproteinase 2; C522362:Mmp2 protein, mouse; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9
keywords: Fc-saxatilin; disintegrin; endothelial permeability; occludin