Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0034063 (pulmonary edema)
 10,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thrombin-induced barrier dysfunction of pulmonary endothelial monolayer is associated with dramatic cytoskeletal reorganization, activation of actomyosin contraction, and gap formation. Phosphorylation of regulatory myosin light chains (MLC) is a key mechanism of endothelial cell (EC) contraction and barrier dysfunction, which is triggered by Ca(2+)/calmodulin-dependent MLC kinase (MLCK) and Rho-associated kinase (Rho-kinase). The role of MLCK in EC barrier regulation has been previously described; however, Rho-mediated pathway in thrombin-induced pulmonary EC dysfunction is not yet precisely characterized. Here, we demonstrate that thrombin-induced decreases in transendothelial electrical resistance (TER) indicating EC barrier dysfunction are universal for human and bovine pulmonary endothelium, and involve membrane translocation and direct activation of small GTPase Rho and its downstream target Rho-kinase. Transient Rho membrane translocation coincided with translocation of upstream Rho activator, guanosine nucleotide exchange factor p115-RhoGEF. Rho mediated activation of downstream target, Rho-kinase induced phosphorylation of the EC MLC phosphatase (MYPT1) at Thr(686) and Thr(850), resulting in MYPT1 inactivation, accumulation of diphospho-MLC, actin remodeling, and cell contraction. The specific Rho-kinase inhibitor, Y27632, abolished MYPT1 phosphorylation, MLC phosphorylation, significantly attenuated stress fiber formation and thrombin-induced TER decrease. Furthermore, expression of dominant-negative Rho and Rho-kinase abolished thrombin-induced stress fiber formation and MLC phosphorylation. Our data, which provide comprehensive analysis of Rho-mediated signal transduction in pulmonary EC, demonstrate involvement of guanosine nucleotide exchange factor, p115-RhoGEF, in thrombin-mediated Rho regulation, and suggest Rho, Rho-kinase, and MYPT1 as potential pharmacological and gene therapy targets critical for prevention of thrombin-induced EC barrier disruption and pulmonary edema associated with acute lung injury.
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PMID:Role of Rho GTPases in thrombin-induced lung vascular endothelial cells barrier dysfunction. 1470 4

Barrier dysfunction of pulmonary endothelial monolayer is associated with dramatic cytoskeletal reorganization, activation of actomyosin contractility, and gap formation. The linkage between the microtubule (MT) network and the contractile cytoskeleton has not been fully explored, however, clinical observations suggest that intravenous administration of anti-cancer drugs and MT inhibitors (such as the vinca alkaloids) can lead to the sudden development of pulmonary edema in breast cancer patients. In this study, we investigated the crosstalk between MT and actomyosin cytoskeleton and characterized specific molecular mechanisms of endothelial cells (EC) barrier dysfunction induced by MT inhibitor nocodazole (ND). Our results demonstrate that MT disassembly by ND induced rapid decreases in transendothelial electrical resistance (TER) and actin cytoskeletal remodeling, indicating EC barrier dysfunction. These effects involved ND-induced activation of Rho GTPase. Rho-mediated activation of its downstream target, Rho-kinase, induced phosphorylation of Rho-kinase effector EC MLC phosphatase (MYPT1) at Thr(696) and Thr(850) resulting in MYPT1 inactivation. Phosphatase inhibition leaded to accumulation of diphospho-MLC, which induced acto-myosin polymerization, stress fiber formation and gap formation. Inhibition of Rho-kinase by Y27632 abolished ND-induced MYPT1 phosphorylation, MLC phosphorylation, and stress fiber formation. In addition, MT preservation via the MT stabilizer paclitaxel, Rho inhibition (via C3 exotoxin, or dominant negative (DN)-Rho, or DN-Rho-kinase) attenuated ND-induced TER decreases, stress fiber formation and MLC phosphorylation. Collectively, our results demonstrate a leading role for Rho-dependent mechanisms in crosstalk between the MT and actomyosin cytoskeleton, and suggest Rho-kinase and MYPT1 as major Rho effectors mediating pulmonary EC barrier disruption in response to ND-induced MT disassembly.
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PMID:Microtubule disassembly induces cytoskeletal remodeling and lung vascular barrier dysfunction: role of Rho-dependent mechanisms. 1528 Oct 89