title: Reactive oxygen species alter brain endothelial tight junction dynamics via RhoA, PI3 kinase, and PKB signaling.
abstract: The blood-brain barrier (BBB) prevents the entrance of circulating molecules and immune cells into the central nervous system. The barrier is formed by specialized brain endothelial cells that are interconnected by tight junctions (TJ). A defective function of the BBB has been described for a variety of neuroinflammatory diseases, indicating that proper regulation is essential for maintaining brain homeostasis. Under pathological conditions, reactive oxygen species (ROS) significantly contribute to BBB dysfunction and inflammation in the brain by enhancing cellular migration. However, a detailed study about the molecular mechanism by which ROS alter BBB integrity has been lacking. Here we demonstrate that ROS alter BBB integrity, which is paralleled by cytoskeleton rearrangements and redistribution and disappearance of TJ proteins claudin-5 and occludin. Specific signaling pathways, including RhoA and PI3 kinase, mediated observed processes and specific inhibitors of these pathways prevented ROS-induced monocyte migration across an in vitro model of the BBB. Interestingly, these processes were also mediated by protein kinase B (PKB/Akt), a previously unknown player in cytoskeleton and TJ dynamics that acted downstream of RhoA and PI3 kinase. Our study reveals new insights into molecular mechanisms underlying BBB regulation and provides novel opportunities for the treatment of neuroinflammatory diseases.
authors.affiliation: Department of Molecular Cell Biology and Immunology, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands.
authors.forename: Gerty
authors.initials: G
authors.lastname: Schreibelt
authors.forename: Gijs
authors.initials: G
authors.lastname: Kooij
authors.forename: Arie
authors.initials: A
authors.lastname: Reijerkerk
authors.forename: Ruben
authors.initials: R
authors.lastname: van Doorn
authors.forename: Sonja I
authors.initials: SI
authors.lastname: Gringhuis
authors.forename: Susanne
authors.initials: S
authors.lastname: van der Pol
authors.forename: Babette B
authors.initials: BB
authors.lastname: Weksler
authors.forename: Ignacio A
authors.initials: IA
authors.lastname: Romero
authors.forename: Pierre-Olivier
authors.initials: PO
authors.lastname: Couraud
authors.forename: Jörg
authors.initials: J
authors.lastname: Piontek
authors.forename: Ingolf E
authors.initials: IE
authors.lastname: Blasig
authors.forename: Christine D
authors.initials: CD
authors.lastname: Dijkstra
authors.forename: Eric
authors.initials: E
authors.lastname: Ronken
authors.forename: Helga E
authors.initials: HE
authors.lastname: de Vries
mesh_terms: D000818:Animals; D002461:Cell Line, Transformed; D006801:Humans; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D019108:Tight Junctions / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D020742:rhoA GTP-Binding Protein