Regulation of bovine brain microvascular endothelial tight junction assembly and barrier function by laminar shear stress

Olga C Colgan, Gail Ferguson, Nora T Collins, Ronan P Murphy, Gerardeane Meade, Paul A Cahill, Philip M Cummins

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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.

Original languageEnglish
Pages (from-to)H3190-7
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume292
Issue number6
DOIs
Publication statusPublished - Jun 2007

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Keywords

  • Actins/metabolism
  • Animals
  • Blood-Brain Barrier/cytology
  • Brain/blood supply
  • Capillary Permeability
  • Cattle
  • Cell Shape
  • Cells, Cultured
  • Dextrans/metabolism
  • Endothelial Cells/metabolism
  • Fluorescein-5-isothiocyanate/analogs & derivatives
  • Membrane Proteins/genetics
  • Microcirculation/cytology
  • Occludin
  • Phosphoproteins/genetics
  • Pulsatile Flow
  • RNA, Messenger/metabolism
  • Stress, Mechanical
  • Sucrose/metabolism
  • Tight Junctions/metabolism
  • Zonula Occludens-1 Protein

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