Histamine and thrombin modulate endothelial focal adhesion through centripetal and centrifugal forces.

Abstract

We examined the contribution of actin-myosin contraction to the modulation of human umbilical vein endothelial cell focal adhesion caused by histamine and thrombin. Focal adhesion was measured as the electrical resistance across a cultured monolayer grown on a microelectrode. Actin-myosin contraction was measured as isometric tension of cultured monolayers grown on a collagen gel. Histamine immediately decreased electrical resistance but returned to basal levels within 3-5 min. Histamine did not increase isometric tension. Thrombin also immediately decreased electrical resistance, but, however, resistance did not return to basal levels for 40-60 min. Thrombin also increased isometric tension. ML-7, an inhibitor of myosin light chain kinase, prevented increases in myosin light chain phosphorylation and increases in tension development in cells exposed to thrombin. ML-7 did not prevent a decline in electrical resistance in cells exposed to thrombin. Instead, ML-7 restored the electrical resistance to basal levels in a shorter period of time (20 min) than cells exposed to thrombin alone. Also, histamine subsequently increased electrical resistance to above basal levels, and thrombin initiated an increase in resistance during the time of peak tension development. Hence, histamine and thrombin modulate endothelial cell focal adhesion through centripetal and centrifugal forces. (

Regulation of Endothelial CD73 by Adenosine: Paracrine Pathway for Enhanced Endothelial Barrier Function

“…Moreover, it has been demonstrated that intracellular levels of cAMP are tightly coupled to myosin light chain activity (41). Pharmacologic maneuvers that increase intracellular levels of cAMP (42) or cGMP (43) result in a dephosphorylation of myosin, a redistribution of actin and myosin II, and a decrease in endothelial isometric tension, indicating that endothelial permeability is likely coupled to myosin light chain kinase activity. Finally, recent in vivo work has suggested that endotoxin-induced increases in vascular permeability are associated with accumulation of neutrophils and that dysfunction may be coupled to elevations in cGMP (44).…”

Small Rho GTPase-mediated actin dynamics at endothelial adherens junctions

“…Conversely, increased actomyosin generated pulling force is important for opening of endothelial cell-cell junctions in response to permeability-inducing factors. 20 By altering the magnitude and direction of the forces that are exerted on cell-cell junctions, actin cytoskeleton rearrangements can change the integrity of VEcadherin-based cell-cell junctions. 21 Thus, a finely balanced regulation of actin network organization, together with myosin-II activity, is needed to produce mechanical forces that drive assembly, maintenance and remodeling of adherens junctions (Fig.…”

Rnd3 as a Novel Target to Ameliorate Microvascular Leakage

“…ROCK can phosphorylate the myosin light chain phosphatase targeting subunit (MYPT‐1), leading to inactivation of myosin light chain phosphatase, and accumulation of myosin light chain phosphorylated on Thr‐18 and Ser‐19 by myosin light chain kinase 11, 12. Several reports have suggested that inflammatory mediators promote excess phosphorylated myosin light chain, which may interact with actin to open intercellular junctions, either through contractile or retractile mechanisms 3, 13, 14, 15, 16, 17, 18. Despite these advances, a caveat to using inhibition of RhoA/ROCK to reduce microvascular hyperpermeability is the fact that this pathway is also important for maintaining endothelial barrier function under noninflammatory conditions,17, 19, 20 as RhoA activation near cell borders promotes endothelial barrier integrity 21.…”