β1-integrin-matrix interactions modulate cerebral microvessel endothelial cell tight junction expression and...

Area of Science:

• Neuroscience
• Vascular Biology
• Cell Biology

Background:

• Focal cerebral ischemia disrupts the blood-brain barrier (BBB), allowing plasma proteins into the brain and causing edema.
• This BBB disruption is associated with a loss of microvessel endothelial beta1-integrins.

Purpose of the Study:

• To investigate the role of beta1-integrin-matrix adhesion in regulating cerebral microvascular endothelial cell permeability.
• To elucidate the signaling pathways involved in beta1-integrin-mediated BBB regulation.

Main Methods:

• Utilized primary rat cerebral microvascular endothelial cell monolayers.
• Interfered with beta1-integrin-matrix adhesion using monoclonal IgM Ha2/5.
• Examined the effects on tight junction proteins (claudin-5, occludin, ZO-1), F-actin conformation, and MLC phosphorylation.
• Investigated the roles of MLC kinase (MLCK) and Rho kinase (ROCK).
• Validated findings in a murine conditional beta1-integrin deletion model.

Main Results:

• Interference with beta1-integrin-matrix adhesion increased endothelial cell permeability.
• This increase was linked to the reorganization of tight junction proteins (claudin-5, occludin, ZO-1).
• Beta1-integrin detachment induced F-actin changes and increased myosin light chain (MLC) phosphorylation.
• Inhibition of MLCK and ROCK abolished the increased permeability.
• Consistent results were observed in a beta1-integrin conditional knockout mouse model.

Conclusions:

• Detachment of beta1-integrins from matrix ligands increases vascular endothelial permeability.
• This process involves tight junction protein reorganization mediated by F-actin conformation changes.
• The beta1-integrin-MLC signaling pathway is activated upon beta1-integrin detachment.
• These findings offer a novel therapeutic strategy for cerebral disorders involving BBB breakdown.