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Endothelial contraction and monolayer hyperpermeability are regulated by Src kinase.
David R Mucha1, Carter L Myers, Richard C Schaeffer
1The Benjamin W. Zweifach Microcirculation Laboratories, Veterans Affairs Medical Center, Tucson, Arizona 85723, USA.
American Journal of Physiology. Heart and Circulatory Physiology
|November 29, 2002
Summary
Src kinase regulates endothelial barrier function by controlling cell contraction and tyrosine phosphorylation. Inhibiting Src kinase improves barrier integrity, while its activation leads to hyperpermeability.
Area of Science:
- Cell Biology
- Biochemistry
- Physiology
Background:
- Endothelial monolayer hyperpermeability is critical for regulating vascular function.
- Myosin light chain phosphorylation (MLCP)-dependent contraction controls endothelial barrier integrity.
- The role of Src-dependent tyrosine phosphorylation in this process requires further elucidation.
Purpose of the Study:
- To investigate the role of Src-dependent tyrosine phosphorylation in modulating endothelial contraction.
- To determine the impact of Src kinase activity on endothelial monolayer barrier function.
- To explore the interplay between MLCP, tyrosine phosphorylation, and endothelial cell contraction.
Main Methods:
- Utilized bovine pulmonary artery endothelial cells (EC).
- Employed calyculin A (CalA), a myosin phosphatase inhibitor, to elevate MLCP.
- Used herbimycin A (HA), a Src family tyrosine kinase inhibitor, to assess Src kinase activity.
- Analyzed MLCP levels, Src kinase activity, protein tyrosine phosphorylation (paxillin, p125(FAK)), and monolayer permeability.
Main Results:
- CalA treatment increased MLCP, Src kinase activity, tyrosine phosphorylation of paxillin and focal adhesion kinase (p125(FAK)), and induced monolayer hyperpermeability.
- CalA-induced changes were sensitive to HA inhibition.
- HA treatment alone improved monolayer barrier formation by reducing MLCP, phosphotyrosine-containing proteins, and paracellular holes.
- CalA-treated EC exhibited contractile morphology with actomyosin filaments and stress fibers linked to phosphotyrosine-containing focal adhesions.
Conclusions:
- Src kinase plays a significant role in regulating endothelial monolayer hyperpermeability.
- Src kinase modulates barrier function through adjustments in tyrosine phosphorylation and MLCP.
- Targeting Src kinase activity represents a potential strategy for controlling endothelial barrier function.