title: Regulation of bovine brain microvascular endothelial tight junction assembly and barrier function by laminar shear stress.
abstract: Blood-brain barrier (BBB) controls paracellular solute diffusion into the brain microenvironment and is maintained primarily by tight junctions between adjacent microvascular endothelial cells. Studies implicate blood flow-associated shear stress as a pathophysiological mediator of BBB function, although detailed biochemical data are scarce. We hypothesize that shear stress upregulates BBB function via direct modulation of expression and properties of pivotal tight-junction proteins occludin and zonula occludens-1 (ZO-1). Bovine brain microvascular endothelial cells (BBMvECs) were exposed to either steady or pulsatile shear stress (10 and 14 dyn/cm(2), respectively) for 24 h. Sheared BBMvECs were monitored for occludin-ZO-1 expression, association, and subcellular localization, and transendothelial permeability of BBMvECs to FITC-dextran and (14)[C]sucrose was assessed. Actin reorganization and BBMvEC realignment were observed following steady shear stress for 24 h. Substantial increases in occludin mRNA and protein expression (2.73 +/- 0.26- and 1.83 +/- 0.03-fold) and in occludin-ZO-1 association (2.12 +/- 0.15-fold) were also observed. Steady shear stress also induced clear relocalization of both proteins to the cell-cell border in parallel with reduced transendothelial permeability to FITC-dextran (but not sucrose). Following pulsatile shear stress, increased protein levels for both occludin and ZO-1 (2.15 +/- 0.02- and 1.67 +/- 0.21-fold) and increased occludin-ZO-1 association (2.91 +/- 0.14-fold) were observed in parallel with a reduction in transendothelial permeability to (14)[C]sucrose. Shear stress upregulates BBMvEC barrier function at the molecular level via modulation of expression, association, and localization of occludin and ZO-1. The pulsatile shear model appeared to give the most profound biochemical responses.
authors.affiliation: Vascular Health Research Centre, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: Olga C
authors.initials: OC
authors.lastname: Colgan
authors.forename: Gail
authors.initials: G
authors.lastname: Ferguson
authors.forename: Nora T
authors.initials: NT
authors.lastname: Collins
authors.forename: Ronan P
authors.initials: RP
authors.lastname: Murphy
authors.forename: Gerardeane
authors.initials: G
authors.lastname: Meade
authors.forename: Paul A
authors.initials: PA
authors.lastname: Cahill
authors.forename: Philip M
authors.initials: PM
authors.lastname: Cummins
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001812:Blood-Brain Barrier / Q000166:cytology / Q000378:metabolism*; D001921:Brain / Q000098:blood supply*; D002199:Capillary Permeability; D002417:Cattle; D048430:Cell Shape; D002478:Cells, Cultured; D003911:Dextrans / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism*; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008833:Microcirculation / Q000166:cytology / Q000378:metabolism; D062793:Occludin; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D011673:Pulsatile Flow; D012333:RNA, Messenger / Q000378:metabolism; D013314:Stress, Mechanical; D013395:Sucrose / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein
chemical_list: D000199:Actins; D003911:Dextrans; D008565:Membrane Proteins; D062793:Occludin; D010750:Phosphoproteins; D012333:RNA, Messenger; D062826:Zonula Occludens-1 Protein; C015219:fluorescein isothiocyanate dextran; D013395:Sucrose; D016650:Fluorescein-5-isothiocyanate