title: Microtubule disassembly increases endothelial cell barrier dysfunction: role of MLC phosphorylation.
abstract: Endothelial cell (EC) barrier regulation is critically dependent on cytoskeletal components (microfilaments and microtubules). Because several edemagenic agents induce actomyosin-driven EC contraction tightly linked to myosin light chain (MLC) phosphorylation and microfilament reorganization, we examined the role of microtubule components in bovine EC barrier regulation. Nocodazole or vinblastine, inhibitors of microtubule polymerization, significantly decreased transendothelial electrical resistance in a dose-dependent manner, whereas pretreatment with the microtubule stabilizer paclitaxel significantly attenuated this effect. Decreases in transendothelial electrical resistance induced by microtubule disruption correlated with increases in lung permeability in isolated ferret lung preparations as well as with increases in EC stress fiber content and MLC phosphorylation. The increases in MLC phosphorylation were attributed to decreases in myosin-specific phosphatase activity without significant increases in MLC kinase activity and were attenuated by paclitaxel or by several strategies (C3 exotoxin, toxin B, Rho kinase inhibition) to inhibit Rho GTPase. Together, these results suggest that microtubule disruption initiates specific signaling pathways that cross talk with microfilament networks, resulting in Rho-mediated EC contractility and barrier dysfunction.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21224, USA. averin@welch.jhu.edu
authors.forename: A D
authors.initials: AD
authors.lastname: Verin
authors.forename: A
authors.initials: A
authors.lastname: Birukova
authors.forename: P
authors.initials: P
authors.lastname: Wang
authors.forename: F
authors.initials: F
authors.lastname: Liu
authors.forename: P
authors.initials: P
authors.lastname: Becker
authors.forename: K
authors.initials: K
authors.lastname: Birukov
authors.forename: J G
authors.initials: JG
authors.lastname: Garcia
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology; D000818:Animals; D002199:Capillary Permeability / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D017097:Electric Impedance; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D008870:Microtubules / Q000502:physiology*; D018994:Myosin Light Chains / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D020741:rho GTP-Binding Proteins / Q000502:physiology
chemical_list: D018994:Myosin Light Chains; D009219:Myosin-Light-Chain Kinase; D010749:Phosphoprotein Phosphatases; D043263:Myosin-Light-Chain Phosphatase; D020741:rho GTP-Binding Proteins