Original Research Article
Stabilization of brain microvascular endothelial barrier function by shear stress involves VE-cadherin signaling leading to modulation of pTyr-occludin levels
Article first published online: 24 AUG 2011
Copyright © 2011 Wiley-Liss, Inc.
Journal of Cellular Physiology
Volume 226, Issue 11, pages 3053–3063, November 2011
How to Cite
Walsh, T. G., Murphy, R. P., Fitzpatrick, P., Rochfort, K. D., Guinan, A. F., Murphy, A. and Cummins, P. M. (2011), Stabilization of brain microvascular endothelial barrier function by shear stress involves VE-cadherin signaling leading to modulation of pTyr-occludin levels. J. Cell. Physiol., 226: 3053–3063. doi: 10.1002/jcp.22655
- Issue published online: 24 AUG 2011
- Article first published online: 24 AUG 2011
- Accepted manuscript online: 1 FEB 2011 09:29AM EST
- Manuscript Accepted: 13 JAN 2011
- Manuscript Received: 27 SEP 2010
- Irish Research Council for Science, Engineering & Technology (Oct 2006). Grant Number: IRCSET ID 493
- Science Foundation Ireland (SFI Research Frontiers Programme). Grant Number: BICF708
Blood–brain barrier (BBB) regulation involves the coordinated interaction of intercellular adherens and tight junctions in response to stimuli. One such stimulus, shear stress, has been shown to upregulate brain microvascular endothelial cell (BMvEC) barrier function, although our knowledge of the signaling mechanisms involved is limited. In this article, we examined the hypothesis that VE-cadherin can transmit shear signals to tight junction occludin with consequences for pTyr-occludin and barrier function. In initial studies, chronic shear enhanced membrane localization of ZO-1 and claudin-5, decreased pTyr-occludin (in part via a dephostatin-sensitive mechanism), and reduced BMvEC permeability, with flow reduction in pre-sheared BMvECs having converse effects. In further studies, VE-cadherin inhibition (VE-cad ΔEXD) blocked shear-induced Rac1 activation, pTyr-occludin reduction, and barrier upregulation, consistent with an upstream role for VE-cadherin in transmitting shear signals to tight junctions through Rac1. As VE-cadherin is known to mediate Rac1 activation via Tiam1 recruitment, we subsequently confirmed that Tiam1 inhibition (Tiam1-C580) could elicit effects similar to VE-cad ΔEXD. Finally, the observed attenuation of shear-induced changes in pTyr-occludin level and barrier phenotype following Rac1 inhibition (NSC23766, T17N) establishes a downstream role for Rac1 in this pathway. In summary, we describe for the first time in BMvECs a role for VE-cadherin in the transmission of physiological shear signals to tight junction occludin through engagement of Tiam1/Rac1 leading to barrier stabilization. A downstream role is also strongly indicated for a protein tyrosine phosphatase in pTyr-occludin modulation. Importantly, these findings suggest an important route of inter-junctional signaling cross-talk during BBB response to flow. J. Cell. Physiol. 226: 3053–3063, 2011. © 2011 Wiley-Liss, Inc.