title: Activation of Rho kinase isoforms in lung endothelial cells during inflammation.
abstract: Rho kinase (ROCK) is a downstream effector of Rho family GTPases, and two highly homologous isoforms, ROCK1 and ROCK2, are similarly inhibited by the widely used pharmacologic inhibitors. In endothelial cells (ECs), activation of ROCK regulates myosin L chain (MLC) phosphorylation, stress fiber formation and permeability increases during inflammation. This study examined isoform-specific ROCK activation in lung ECs in vitro using human pulmonary microvascular ECs and ex vivo using freshly isolated lung ECs from mice. In unstimulated human as well as mouse lung ECs, ROCK2 activity was greater than ROCK1 activity. TNF-alpha stimulation induced activation of both ROCK1 and ROCK2 in cultured human ECs. Studies using lung ECs freshly isolated from mice showed that intratracheal instillation of LPS induced ROCK activation in lung ECs that was inhibited by treating animals with fasudil, a pharmacologic ROCK inhibitor, and that both ROCK1 and ROCK2 were activated. Small interference RNA targeting ROCK1 or ROCK2 was used to examine their functions in regulating MLC phosphorylation and permeability increases induced by TNF-alpha in human ECs. TNF-alpha-induced MLC phosphorylation required ROCK activation. Inhibition of ROCK1 alone was not sufficient to prevent TNF-alpha-induced MLC phosphorylation, whereas inhibition of ROCK2 prevented TNF-alpha-induced late MLC phosphorylation at 24 h. Although ROCK1 was dispensable for TNF-alpha-induced MLC phosphorylation, ROCK1 was required for TNF-alpha-induced early permeability increases. Therefore, ROCK1 and ROCK2 are both activated by TNF-alpha and can be functionally separated in the signaling pathways leading to TNF-alpha-induced MLC phosphorylation and permeability increases.
authors.affiliation: The Tumor Immunology Laboratory, Division of Surgical Oncology, Department of Surgery, Columbia University, New York, NY 10032, USA.
authors.forename: Phyllus Y
authors.initials: PY
authors.lastname: Mong
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000818:Animals; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D007249:Inflammation / Q000201:enzymology* / Q000276:immunology; D007527:Isoenzymes / Q000276:immunology / Q000378:metabolism; D008168:Lung / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D051379:Mice; D018994:Myosin Light Chains / Q000378:metabolism; D010766:Phosphorylation; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D054460:rho-Associated Kinases / Q000276:immunology / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D018994:Myosin Light Chains; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D054460:rho-Associated Kinases