Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antagonists of myosin light chain (MLC) kinase (MLCK) and Rho kinase (ROK) are thought to inhibit hypoxic pulmonary vasoconstriction (HPV) by decreasing the concentration of phosphorylated MLC at any intracellular Ca(2+) concentration ([Ca(2+)](i)) in pulmonary arterial smooth muscle cells (PASMC); however, these antagonists can also decrease [Ca(2+)](i). To determine whether MLCK and ROK antagonists alter Ca(2+) signaling in HPV, we measured the effects of ML-9, ML-7, Y-27632, and HA-1077 on [Ca(2+)](i), Ca(2+) entry, and Ca(2+) release in rat distal PASMC exposed to hypoxia or depolarizing concentrations of KCl. We performed parallel experiments in isolated rat lungs to confirm the inhibitory effects of these agents on pulmonary vasoconstriction. Our results demonstrate that MLCK and ROK antagonists caused concentration-dependent inhibition of hypoxia-induced increases in [Ca(2+)](i) in PASMC and HPV in isolated lungs and suggest that this inhibition was due to blockade of Ca(2+) release from the sarcoplasmic reticulum and Ca(2+) entry through store- and voltage-operated Ca(2+) channels in PASMC. Thus MLCK and ROK antagonists might block HPV by inhibiting Ca(2+) signaling, as well as the actin-myosin interaction, in PASMC. If effects on Ca(2+) signaling were due to decreased phosphorylated myosin light chain concentration, their diversity suggests that MLCK and ROK antagonists may have acted by inhibiting myosin motors and/or altering the cytoskeleton in a manner that prevented achievement of required spatial relationships among the cellular components of the response.
Am J Physiol Lung Cell Mol Physiol 2007 Sep
PMID:Ca2+ signaling in hypoxic pulmonary vasoconstriction: effects of myosin light chain and Rho kinase antagonists. 1757 9

Adhesion of myeloma cells to bone marrow stromal cells is now considered to play a critical role in chemoresistance. However, little is known about the molecular mechanism governing cell adhesion-mediated drug resistance (CAM-DR) of myeloma cells. In this study, we focused our interests on the implication of the Wnt signal in CAM-DR. We first screened the expression of Wnt family in myeloma cell lines and found that Wnt3 was overexpressed in all the myeloma cells examined. KMS-5 and ARH77, which highly expressed Wnt3 protein, tightly adhered to human bone marrow stromal cells, and accumulation of beta-catenin and GTP-bounded RhoA was observed in these myeloma cell lines. Conversely, RPMI8226 and MM1S, which modestly expressed Wnt3 protein, rather weakly adhered to human bone marrow stromal. We then examined the relevance of Wnt3 expression to adhesive property to stromal cells and to CAM-DR of myeloma cells. KMS-5 and ARH-77 exhibited apparent CAM-DR against doxorubicin. This CAM-DR was significantly reduced by anti-integrin beta(1) antibody, anti-integrin alpha(6) antibody and a Wnt-receptor competitor, secreted Frizzled-related protein-1, and Rho kinase inhibitor Y27632, but not by the specific inhibitor of canonical signaling (Dickkopf-1), indicating that Wnt-mediated CAM-DR that is dependent on integrin alpha(6)/beta(1) (VLA-6)-mediated attachment to stromal cells is induced by the Wnt/RhoA/Rho kinase pathway signal. This CAM-DR was also significantly reduced by Wnt3 small interfering RNA transfer to KMS-5. These results indicate that Wnt3 contributes to VLA-6-mediated CAM-DR via the Wnt/RhoA/ROCK pathway of myeloma cells in an autocrine manner. Thus, the Wnt3 signaling pathway could be a promising molecular target to overcome CAM-DR of myeloma cells.
Mol Cancer Ther 2007 Jun
PMID:Wnt3/RhoA/ROCK signaling pathway is involved in adhesion-mediated drug resistance of multiple myeloma in an autocrine mechanism. 1757 6

Although the RhoA/Rho kinase (RhoA/ROK) pathway has been extensively investigated, its roles and downstream signaling pathways are still not well understood in myogenic processes. Therefore, we examined the effects of RhoA/ROK on myogenic processes and their signaling molecules using H9c2 and C2C12 cells. Increases in RhoA/ROK activities and serine phosphorylation levels of insulin receptor substrate (IRS)-1 (Ser307 and Ser636/639) and IRS-2 were found in proliferating myoblasts, whereas IRS-1/2 tyrosine phosphorylation and phosphatidylinositol (PI) 3-kinase activity increased during the differentiation process. ROK strongly bound to IRS-1/2 in proliferation medium but dissociated from them in differentiation medium (DM). ROK inactivation by a ROK inhibitor, Y27632, or a dominant-negative ROK, decreased IRS-1/2 serine phosphorylation with increases in IRS-1/2 tyrosine phosphorylation and PI 3-kinase activity, which led to muscle differentiation even in proliferation medium. Inhibition of ROK also enhanced differentiation in DM. ROK activation by a constitutive active ROK blocked muscle differentiation with the increased IRS-1/2 serine phosphorylation, followed by decreases in IRS-1/2 tyrosine phosphorylation and PI 3-kinase activity in DM. Interestingly, fibroblast growth factor-2 added to DM also blocked muscle differentiation through RhoA/ROK activation. Fibroblast growth factor-2 blockage of muscle differentiation was reversed by Y27632. Collectively, these results suggest that the RhoA/ROK pathway blocks muscle differentiation by phosphorylating IRS proteins at serine residues, resulting in the decreased IRS-1/2 tyrosine phosphorylation and PI 3-kinase activity. The absence of the inhibitory effects of RhoA/ROK in DM due to low concentrations of myogenic inhibitory growth factors seems to allow IRS-1/2 tyrosine phosphorylation, which stimulates muscle differentiation via transducing normal myogenic signaling.
Mol Endocrinol 2007 Sep
PMID:RhoA/Rho kinase blocks muscle differentiation via serine phosphorylation of insulin receptor substrate-1 and -2. 1757 8

Transforming growth factor beta (TGF-beta) contributes to the progression of pulmonary fibrosis through up-regulation of alpha-smooth muscle actin (alpha-SMA) as lung myofibroblast differentiation. Bioactive sphingosine 1-phosphate (S1P) has been shown to mimic TGF-beta signals; however, the function of S1P in lung fibrotic process has not been well documented. We found, in a mouse model of bleomycin lung fibrosis, that SPHK1 and alpha-SMA were colocalized within lung fibrotic foci and that these expressions were significantly increased in primary cultured fibroblasts. Using human lung fibroblasts WI-38, we explored the rationale of sphingosine kinase (SPHK) with TGF-beta1 stimulation. SPHK inhibitors and small interference RNA (siRNA) targeted SPHK1 decreased alpha-SMA and fibronectin expression up-regulated by TGF-beta1. In the meantime, SPHK1 inhibition did not affect smad2 phosphorylation in response to TGF-beta1. Then we examined whether S1P receptors transactivation may affect TGF-beta signals. siRNA against S1P(2) and S1P(3), but not S1P(1), reduced alpha-SMA expression as well as Y-27632, Rho kinase inhibitor. We also detected activation of Rho GTPase upon stimulation of TGF-beta1 on the cell membrane where S1P(2) or S1P(3) was overexpressed. These data suggested that SPHK1 activation by TGF-beta1 leads to Rho-associated myofibroblasts differentiation mediated by transactivated S1P receptors in the lung fibrogenic process.
Am J Respir Cell Mol Biol 2007 Oct
PMID:Sphingosine kinase 1 regulates differentiation of human and mouse lung fibroblasts mediated by TGF-beta1. 1764 Dec 98

The small GTP-binding protein and its downstream effector Rho kinase play an important role in the regulation of vasoconstrictor tone. Rho kinase activation maintains increased pulmonary vascular tone and mediates the vasoconstrictor response to nitric oxide (NO) synthesis inhibition in chronically hypoxic rats and in the ovine fetal lung. However, the role of Rho kinase in mediating pulmonary vasoconstriction after NO synthesis inhibition has not been examined in the intact rat. To address this question, cardiovascular responses to the Rho kinase inhibitor fasudil were studied at baseline and after administration of an NO synthesis inhibitor. In the intact rat, intravenous injections of fasudil cause dose-dependent decreases in systemic arterial pressure, small decreases in pulmonary arterial pressure, and increases in cardiac output. L-NAME caused a significant increase in pulmonary and systemic arterial pressures and a decrease in cardiac output. The intravenous injections of fasudil after L-NAME caused dose-dependent decreases in pulmonary and systemic arterial pressure and increases in cardiac output, and the percent decreases in pulmonary arterial pressure in response to the lower doses of fasudil were greater than decreases in systemic arterial pressure. The Ca(++) entry blocker isradipine also decreased pulmonary and systemic arterial pressure in L-NAME-treated rats. Infusion of sodium nitroprusside restored pulmonary arterial pressure to baseline values after administration of L-NAME. These data provide evidence in support of the hypothesis that increases in pulmonary and systemic vascular resistance following L-NAME treatment are mediated by Rho kinase and Ca(++) entry through L-type channels, and that responses to L-NAME can be reversed by an NO donor.
Am J Physiol Lung Cell Mol Physiol 2007 Nov
PMID:Rho kinase and Ca2+ entry mediate increased pulmonary and systemic vascular resistance in L-NAME-treated rats. 1776 87

Cadherin-mediated cell-cell adhesion controls the morphology and function of epithelial cells and is a critical component of the pathology of chronic inflammatory disorders. Dynamic interactions between cadherins and the actin cytoskeleton are required for stable cell-cell contact. Besides actin, microtubules also target intercellular, cadherin-based junctions and contribute to their formation and stability. Here, we studied the role of microtubules in conjunction with Rho-like GTPases in the regulation of lung epithelial barrier function using real-time monitoring of transepithelial electrical resistance. Unexpectedly, we found that disruption of microtubules promotes epithelial cell-cell adhesion. This increase in epithelial barrier function is accompanied by the accumulation of beta-catenin at cell-cell junctions, as detected by immunofluorescence. Moreover, we found that the increase in cell-cell contact, induced by microtubule depolymerization, requires signaling through a RhoA/Rho kinase pathway. The Rac-1 GTPase counteracts this pathway, because inhibition of Rac-1 signaling rapidly promotes epithelial barrier function, in a microtubule- and RhoA-independent fashion. Together, our data suggest that microtubule-RhoA-mediated signaling and Rac-1 control lung epithelial integrity through counteracting independent pathways.
Am J Physiol Lung Cell Mol Physiol 2007 Nov
PMID:Microtubule dynamics and Rac-1 signaling independently regulate barrier function in lung epithelial cells. 1782 48

Extracellular signal-regulated kinases (ERK) have fundamental roles in tumor progression. However, human clinical trials have shown little or no effect of inhibitors of their upstream signaling molecule, mitogen-activated protein kinase/ERK kinase (MEK), in advanced cancers. To determine the molecular mechanism underlying the limited antitumor effect, we cultured two human renal carcinoma cell lines, ACHN cells and VMRC-RCW cells in the presence of a MEK inhibitor PD98059 for more than 4 weeks (PD98059-exposed cells). PD98059-exposed ACHN cells showed elongated cell shape with scattering morphology, increase in vimentin expression, loss of beta-catenin junctional localization, stress fiber formation, and increased motility. In contrast, VMRC-RCW cells showed scattered phenotype without PD98059-treatment, and this treatment failed to increase the expression of vimentin. Rho A activity was increased in PD98059-exposed ACHN cells. In these cells, enhanced stress fiber formation and motility were observed, both of which were inhibited by treatment with small interfering RNA for Rho A or an Rho kinase inhibitor Y27632. Our results suggest that long-term exposure of human renal carcinoma cells to PD98059 increases cell motility by upregulating Rho A-Rho kinase signaling.
Mol Cell Biochem 2008 Feb
PMID:Long-term exposure of human renal carcinoma cells to PD98059 induces epithelial-mesenchymal transition-like phenotype and enhanced motility. 1800 Jul 41

Lysophosphatidic acid (LPA), via interaction with its G-protein coupled receptors, is involved in various pathological conditions. Extracellular LPA is mainly produced by the enzyme autotaxin (ATX). Using fibroblast-like synoviocytes (FLS) isolated from synovial tissues of patients with rheumatoid arthritis (RA), we studied the expression profile of LPA receptors, LPA-induced cell migration, and interleukin (IL)-8 and IL-6 production. We report that FLS express LPA receptors LPA(1-3). Moreover, exogenously applied LPA induces FLS migration and secretion of IL-8/IL-6, whereas the LPA(3) agonist l-sn-1-O-oleoyl-2-methyl-glyceryl-3-phosphothionate (2S-OMPT) stimulates cytokine synthesis but not cell motility. The LPA-induced FLS motility and cytokine production are suppressed by LPA(1/3) receptor antagonists diacylglycerol pyrophosphate and (S)-phosphoric acid mono-(2-octadec-9-enoylamino-3-[4-(pyridine-2-ylmethoxy)-phenyl]-propyl) ester (VPC32183). Signal transduction through p42/44 mitogen-activated protein kinase (MAPK), p38 MAPK, and Rho kinase is involved in LPA-mediated cytokine secretion, whereas LPA-induced cell motility requires p38 MAPK and Rho kinase but not p42/44 MAPK. Treatment of FLS with tumor necrosis factor-alpha (TNF-alpha) increases LPA(3) mRNA expression and correlates with enhanced LPA- or OMPT-induced cytokine production. LPA-mediated superproduction of cytokines by TNF-alpha-primed FLS is abolished by LPA(1/3) receptor antagonists. We also report the presence of ATX in synovial fluid of patients with RA. LPA(1/3) receptor antagonists and ATX inhibitors reduce the synovial fluid-induced cell motility. Together the data suggest that LPA(1) and LPA(3) may contribute to the pathogenesis of RA through the modulation of FLS migration and cytokine production. The above results provide novel insights into the relevance of LPA receptors in FLS biology and as potential therapeutic targets for the treatment of RA.
Mol Pharmacol 2008 Feb
PMID:Regulation of lysophosphatidic acid receptor expression and function in human synoviocytes: implications for rheumatoid arthritis? 1800 45

The actin cytoskeleton controls multiple cellular functions, including cell morphology, movement, and growth. Accumulating evidence indicates that oncogenic activation of the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase 1/2 (MEK/ERK1/2) pathway is accompanied by actin cytoskeletal reorganization. However, the signaling events contributing to actin cytoskeleton remodeling mediated by aberrant ERK1/2 activation are largely unknown. Mutant B-RAF is found in a variety of cancers, including melanoma, and it enhances activation of the MEK/ERK1/2 pathway. We show that targeted knockdown of B-RAF with small interfering RNA or pharmacological inhibition of MEK increased actin stress fiber formation and stabilized focal adhesion dynamics in human melanoma cells. These effects were due to stimulation of the Rho/Rho kinase (ROCK)/LIM kinase-2 signaling pathway, cumulating in the inactivation of the actin depolymerizing/severing protein cofilin. The expression of Rnd3, a Rho antagonist, was attenuated after B-RAF knockdown or MEK inhibition, but it was enhanced in melanocytes expressing active B-RAF. Constitutive expression of Rnd3 suppressed the actin cytoskeletal and focal adhesion effects mediated by B-RAF knockdown. Depletion of Rnd3 elevated cofilin phosphorylation and stress fiber formation and reduced cell invasion. Together, our results identify Rnd3 as a regulator of cross talk between the RAF/MEK/ERK and Rho/ROCK signaling pathways, and a key contributor to oncogene-mediated reorganization of the actin cytoskeleton and focal adhesions.
Mol Biol Cell 2008 Feb
PMID:B-RAF regulation of Rnd3 participates in actin cytoskeletal and focal adhesion organization. 1804 87

Unique among the vascular beds, loss of endothelial integrity in the pulmonary microcirculation due to injury can lead to rapidly fatal hypoxemia. The ability to regain confluence and re-establish barrier function is central to restoring proper gas exchange. The adult respiratory distress syndrome (ARDS) is a heterogeneous disease, however, meaning that endothelial cells within different regions of the lung do not likely see the same oxygen tension as they attempt to proliferate and re-establish an intact endothelial monolayer; the effect of hypoxia on the integrity of this newly formed endothelial monolayer is not clear. Immortalized human pulmonary microvascular endothelial cells (PMVEC) (ST1.6R cells) were sparsely plated and grown to confluence over 4 days in either normoxia (21% oxygen) or hypoxia (5% oxygen). Confluence attained in a hypoxic environment resulted in a tighter, less permeable endothelial monolayer (as determined by an increase in transendothelial electrical resistance, decreased permeability to fluorescently labeled macromolecules, and decreased hydraulic conductance). PMVEC grown to confluence under hypoxia had decreased RhoA activity; consistent with this finding, inhibition of Rho kinase, a well-described downstream target of RhoA, markedly increased electrical resistance in normoxic, but not hypoxic, PMVEC. These results were confirmed in primary human and rat PMVEC. These data suggest that PMVEC grown to confluence under hypoxia form a tighter monolayer than similar cells grown under normoxia. This tighter barrier appears to be due, in part, to the inhibition of RhoA activity in hypoxic cells.
Am J Respir Cell Mol Biol 2008 Apr
PMID:Pulmonary microvascular endothelial cells form a tighter monolayer when grown in chronic hypoxia. 1804 5


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