Rho-kinase inhibitor upregulates migration by altering focal adhesion formation via the Akt pathway in colon cancer cells

Although Rho-kinase is reportedly implicated in carcinogenesis and the progression of human cancers, its precise mechanism has not been fully elucidated. We recently reported that Rho-kinase negatively regulates epidermal growth factor (EGF)-stimulated cancer progression in SW480 colon cancer cells. In the present study, we investigated the effect of Rho-kinase on the migration of SW480 colon cancer cells and the mechanism underlying the involvement of Rho-kinase. Interestingly, (R)-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide, 2HCl (Y27632), a specific inhibitor of Rho-kinase, dose-dependently enhanced cell migration. SW480 cells spontaneously release vascular endothelial growth factor (VEGF), however, Y27632 had little effect on its release. While Rho-kinase, which is generally phosphorylated in unstimulated cells, was clearly suppressed by Y27632, exogenous VEGF did not affect its phosphorylation. Immunofluorescence microscopy revealed that Y27632 caused a dramatic change in the localization of focal adhesion components, vinculin, phosphorylated caveolin-1 and tyrosine-phosphorylated proteins in SW480 cells. Furthermore, Akt inhibitor restored the loss of vinculin-stained focal adhesion formation induced by Y27632. We also observed similar effects for Y27632 on the migration and localization of focal adhesion components such as vinculin in another colon cancer cell line, HT29. Taken together, these results strongly suggest that Rho-kinase negatively regulates the migration of colon cancer cells by altering focal adhesion formation via the Akt pathway.     

Simvastatin attenuated cerebrovascular cell proliferation in the development of hypertension through Rho/Rho-kinase pathway

The cerebrovascular remodeling is a prominent feature of hypertension and considered as a major risk of stroke. Statins may suppress the activation of the Rho/Rho-kinase pathway and have pleiotropic actions against the development of vascular remodeling. We hypothesized that the inhibition of the Rho/Rho-kinase pathway by simvastatin during hypertension could recuperate the pathological changes of basilar artery through the downregulation of cell proliferation. To resolve the problem, we used 2-kid, 2-clip rat as a hypertension model and evaluated the effect of simvastatin on the Rho/Rho-kinase pathway. In addition, we assessed the changes of the proliferation rate by CCK-8 assay in basilar artery smooth muscle cells. Our results from this study showed that a continuous increase in the plasma endothelin-1 (ET-1) concentration and the Rho/Rho-kinase activity was positively correlated with changes in blood pressure in the hypertensive rat. Simvastatin ameliorated the upregulated Rho/Rho-kinase activity and cell proliferation during hypertension. Moreover, simvastatin, the RhoA inhibitor C3, and the RhoA-kinase inhibitor Y27632 all attenuated the proliferation rate induced by ET-1 in basilar artery smooth muscle cells via the Rho/Rho-kinase signaling pathway. In conclusion, simvastatin attenuated ET-1-induced proliferation through the Rho/Rho-kinase signaling pathway in hypertensive rat basilar artery, and it may be an excellent reagent to protect vascular remodeling and stroke.     

Differential Rho-kinase dependency of full and partial muscarinic receptor agonists in airway smooth muscle contraction

In airway smooth muscle (ASM), full and partial muscarinic receptor agonists have been described to have large differences in their ability to induce signal transduction, including Ca2+-mobilization. Despite these differences, partial agonists are capable of inducing a submaximal to maximal ASM contraction. To further elucidate transductional differences between full and partial muscarinic receptor agonists, we investigated the contribution of Rho-kinase (an important regulator of Ca2+-sensitization) to methacholine-, pilocarpine- and McN-A-343-induced bovine tracheal smooth muscle (BTSM) contraction, using the selective Rho-kinase inhibitor Y-27632. In addition, we measured Ca2+-mobilization and -influx in BTSM cells in response to these agonists in the absence and presence of Y-27632. Whereas treatment with Y-27632 (1 microM) significantly decreased potency (pEC50) for all agonists, maximal contraction (Emax) was reduced by 23.4+/-2.8 and 50.4+/-7.9% for the partial agonists pilocarpine and McN-A-343, respectively, but was unaffected for the full agonist methacholine. However, Emax of methacholine became Rho-kinase dependent after taking away its receptor reserve using the irreversible muscarinic receptor antagonist propylbenzilylcholine mustard. Pilocarpine and McN-A-343 induced a very small Ca2+-mobilization and -influx as compared to methacholine. In addition, an inverse relationship of these two parameters with the Rho-kinase dependency was observed. Interestingly, no inhibitory effects of Y-27632 were observed on Ca2+-mobilization and-influx for all three agonists, indicating that the effects of Y-27632 on contraction are most likely on the level of Ca2+-sensitization. In conclusion, in contrast to the full agonist methacholine, the partial muscarinic receptor agonists pilocarpine and McN-A-343 are dependent on Rho-kinase for their maximal contractile effects, presumably as a consequence of differences in transductional reserve, indicating an agonist-dependent role for Rho-kinase in ASM contraction. Moreover, an inverse relationship exists between Rho-kinase dependency and both Ca2+-mobilization and Ca2+-influx for these agonists.     

Fluvastatin induces apoptosis in rat neonatal cardiac myocytes: a possible mechanism of statin-attenuated cardiac hypertrophy

Hydroxymethylglutaryl CoA (HMG-CoA) reductase inhibitors (statins) have been shown to reduce atherosclerotic cardiovascular mortality and morbidity. Recent evidence indicates that statins may also exert direct effects on vascular wall cells (including endothelial cells and smooth muscle cells) independently of their hypocholesterolemic properties. However, little is known about whether statins have direct effects on myocardium. The effect of lipophilic and hydrophilic statins (fluvastatin and pravastatin) on apoptosis and protein synthesis in rat neonatal cardiac myocytes was investigated. The presence of apoptosis was evaluated by morphologic criteria, electrophoresis of DNA fragments, 4",6"-diamidine-2"-phenylindole (DAPI) staining, and TUNEL assay. Protein synthesis was measured by H-leucine incorporation into the cells. Fluvastatin, but not pravastatin, induced apoptosis in cardiac myocytes in a time- and dose-dependent manner. The pro-apoptotic effect of fluvastatin was reversed in the presence of mevalonate or geranylgeranyl-pyrophosphate (GGPP), but not in the presence of squalene. The addition of protein prenylation inhibitor perillic acid and Rho-kinase inhibitor Y27632 significantly increased apoptosis. Fluvastatin decreased RhoA protein in the membrane fraction, whereas there were no significant changes of the RhoA protein in the cytosol fraction. Interleukin-1beta-stimulated H-leucine incorporation was completely inhibited by fluvastatin, but not by pravastatin. The findings suggest that fluvastatin induces apoptosis in cardiac myocytes via protein prenylation and the subsequent inhibition of Rho, and may play a role in the pathogenesis of cardiac hypertrophy and remodeling.     

RhoA/Rho-kinase as a therapeutic target in asthma

Rho-kinase is an effector molecule of RhoA, a monomeric GTP-binding protein, and causes Ca(2+) sensitization via inactivation of myosin phosphatase. The major physiological functions of Rho-kinase include contraction, migration, and proliferation in cells. These actions are thought to be related to the pathophysiological features of asthma, i.e., airflow limitation, airway hyperresponsiveness, beta-adrenergic desensitization, eosinophil recruitment and airway remodeling. Here, the roles of RhoA/Rho-kinase in the pathophysiology and treatment of asthma were investigated. In airway smooth muscle, pre-exposure to chemical mediators released from inflammatory cells markedly enhances methacholine-induced contraction without elevating intracellular concentrations of Ca(2+). This augmented responsiveness to methacholine involves the phosphorylation of myosin phosphatase targeting protein 1 (MYPT1) via Rho-kinase, however, it is attenuated by pre-treatment with Rho-kinase inhibitors such as Y-27632 and HA-1077. Airway smooth muscle contraction due to asthma-related substances such as contractile agonists and reactive oxygen species is suppressed by these Rho-kinase inhibitors. Reduced responsiveness to beta-adrenergic receptor agonists occurs via Ca(2+) sensitization, after exposure to lysophospholipids and proteases released from inflammatory cells. This beta-adrenergic desensitization is also attenuated in the presence of Y-27632. Furthermore, the proliferation of airway smooth muscle cells is elevated by Rho-kinase, however, it is markedly suppressed by Y-27632. Antigen challenges cause hyperresponsiveness and eosinophilia in the airways; however, these reactions are markedly suppressed by these Rho-kinase inhibitors. These findings indicate that RhoA/Rho-kinase is involved in the pathophysiology of asthma, and suggest that Rho-kinase inhibitors have therapeutic potential for prohibiting these features. In conclusion, RhoA/Rho-kinase is a novel target molecule for the treatment of asthma.     

Role of Rho-kinase in guinea-pig gallbladder smooth muscle contraction

Guinea-pig gallbladder smooth muscle contractions can be elicited pharmacologically by a range of mechanisms. The involvement of Rho-kinase in contractions mediated by receptor-dependent and receptor-independent mechanisms was investigated using the Rho-kinase inhibitor (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexane carboxamide (Y-27632). In a separate series of experiments, the role of Rho-kinase in the contractile response to Ca2+ entry through store-operated Ca2+ channels and to electrical field stimulation was also examined. Y-27632 (10 microM), which caused a significant decrease (P<0.0005) in basal resting tone, significantly inhibited gallbladder contractions evoked by cumulative additions of the G-protein-coupled agonists, carbachol (1 nM-100 microM; P<0.05) and cholecystokinin (10 nM-1 microM; P<0.005). Y-27632 also inhibited the contractions evoked by a single addition of the sarcoplasmic reticulum ATPase inhibitor, thapsigargin (1 microM; P<0.0005) and cumulative additions of KCl (10-85 mM; P<0.0005). The contractile response to Ca2+ entry through store-operated Ca2+ channels was significantly inhibited by Y-27632 (P<0.05) as were the contractile responses evoked by electrical field stimulation (2-25 Hz; P<0.0005). In contrast, Y-27632 had no significant effect on contractions evoked by phorbol 12,13-dibutyrate (0.1 nM-1 microM; a protein kinase C activator) or by the phosphatase inhibitor, cantharidin (100 microM). In conclusion, Rho-kinase contributes to the contractile response in guinea-pig gallbladder smooth muscle evoked by both G-protein-coupled and non-G-protein-coupled mechanisms in addition to contributing to the maintenance of basal tone. It also contributes to the contractile responses resulting from electrical field stimulation and store-operated Ca2+ channel entry.     

Role of Rho-kinase in maintaining airway smooth muscle contractile phenotype

This study aims to investigate the role of Rho-kinase in phenotype switching and proliferation of bovine tracheal smooth muscle. To induce different phenotypic states, bovine tracheal smooth muscle strips were cultured (8 days) in 10% foetal bovine serum (foetal bovine serum, less contractile phenotype) or insulin (1 microM, hypercontractile phenotype) and compared to strips cultured in serum-free medium. In contraction experiments, the Rho-kinase inhibitor (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexane carboxamide (Y-27632, 1 microM) decreased sensitivity to methacholine and KCl and lowered maximal responsiveness to KCl in all strips irrespective of the phenotype present. To investigate the effects of Rho-kinase bovine tracheal smooth muscle phenotypic regulation, strips were pretreated with Y-27632 (1 microM) for 8 days. This resulted in a decreased maximal contractility to both methacholine and KCl, quantitatively comparable to the decrease in contractility induced by platelet-derived growth factor (PDGF, 10 ng/ml). The combination of Y-27632 and PDGF responded additively. Y-27632 did not affect basal or PDGF-induced bovine tracheal smooth muscle cell proliferation, determined both as increases in [3H]thymidine incorporation and cell number. Inhibitors of the p42/p44 mitogen-activated protein kinase (MAPK) pathway, the p38 MAPK pathway and the phosphatidyl inositol (PI) 3-kinase pathway all inhibited PDGF-induced proliferation and phenotype changes. These results show that the functional contribution of Rho-kinase to bovine tracheal smooth muscle contraction is not dependent on phenotypic state. In addition, Rho-kinase is not involved in phenotypic modulation or proliferation induced by PDGF, whereas p42/p44 MAPK, p38 MAPK and PI 3-kinase are. Rho-kinase is, however, a major regulator involved in the basal maintenance of contractility in bovine tracheal smooth muscle.     

Rho-kinase inhibitor inhibits both myosin phosphorylation-dependent and -independent enhancement of myofilament Ca2+ sensitivity in the bovine middle cerebral artery

The role of Rho kinase in Ca2+ sensitization of the contractile apparatus in smooth muscle was investigated in the bovine middle cerebral artery. U46619, a thromboxane A2 analog, induced a greater sustained contraction with a smaller [Ca2+]i elevation than that seen with 118 mm K+. The level of myosin light chain (MLC) phosphorylation obtained in the initial phase of the contraction was higher than that seen with 118 mm K+; thereafter, it gradually declined to a comparable level in the late phase. During the steady state of the U46619-induced contraction, Y27632 (10 microM), a Rho-kinase inhibitor, partially inhibited [Ca2+]i, although it substantially inhibited tension and MLC phosphorylation. Wortmannin (10 microM), an MLC kinase inhibitor, had no significant effect on [Ca2+]i, but it completely inhibited MLC phosphorylation and partially inhibited tension. The wortmannin-resistant tension development was thus not associated with MLC phosphorylation, and this component was completely inhibited by Y27632. In conclusion, U46619 enhanced Ca2+ sensitivity in a manner both dependent and independent of MLC phosphorylation in the bovine middle cerebral artery. Both mechanisms of Ca2+ sensitization can be inhibited by the Rho-kinase inhibitor.     

Contribution of Rho-kinase to membrane excitability of murine colonic smooth muscle

BACKGROUND AND PURPOSE

The Rho-kinase pathway regulates agonist-induced contractions in several smooth muscles, including the intestine, urinary bladder and uterus, via dynamic changes in the Ca²⁺ sensitivity of the contractile apparatus. However, there is evidence that Rho-kinase also modulates other cellular effectors such as ion channels.

EXPERIMENTAL APPROACH

We examined the regulation of colonic smooth muscle excitability by Rho-kinase using conventional microelectrode recording, isometric force measurements and patch-clamp techniques.

KEY RESULTS

The Rho-kinase inhibitors, Y-27632 and H-1152, decreased nerve-evoked on- and off-contractions elicited at a range of frequencies and durations. The Rho-kinase inhibitors decreased the spontaneous contractions and the responses to carbachol and substance P independently of neuronal inputs, suggesting Y-27632 acts directly on smooth muscle. The Rho-kinase inhibitors significantly reduced the depolarization in response to carbachol, an effect that cannot be due to regulation of Ca²⁺ sensitization. Patch-clamp experiments showed that Rho-kinase inhibitors reduce GTPγS-activated non-selective cation currents.

CONCLUSIONS AND IMPLICATIONS

The Rho-kinase inhibitors decreased contractions evoked by nerve stimulation, carbachol and substance P. These effects were not solely due to inhibition of the Ca²⁺ sensitization pathway, as the Rho-kinase inhibitors also inhibited the non-selective cation conductances activated by excitatory transmitters. Thus, Rho-kinase may regulate smooth muscle excitability mechanisms by regulating non-selective cation channels as well as changing the Ca²⁺ sensitivity of the contractile apparatus.     

Tumor necrosis factor-alpha-induced activation of RhoA in airway smooth muscle cells: role in the Ca2+ sensitization of myosin light chain20 phosphorylation

Tumor necrosis factor-alpha (TNF), an inflammatory cytokine, has a potentially important role in the pathogenesis of bronchial asthma and may contribute to airway hyper-responsiveness. Recent evidence has revealed that TNF can increase the Ca(2+) sensitivity of agonist-stimulated myosin light chain(20) (MLC(20)) phosphorylation and contractility in guinea pig airway smooth muscle (ASM). In the present study, the potential intracellular pathways responsible for this TNF-induced Ca(2+) sensitization were investigated. In permeabilized cultured guinea pig ASM cells, recombinant human TNF stimulated an increase in Ca(2+)-activated MLC(20) phosphorylation under Ca(2+) "clamp" conditions. This increased MLC(20) phosphorylation was inhibited by preincubation with the Rho-kinase inhibitor Y27632. TNF also increased the proportion of GTP-bound RhoA, as measured using rhotekin Rho-binding domain, in a time course compatible with a role in the TNF-induced Ca(2+) sensitization. In cultured human ASM cells, recombinant human TNF also activated RhoA with a similar time course. In addition, TNF stimulated phosphorylation of the regulatory subunit of the myosin phosphatase, which was inhibited by Y27632. Although human ASM cells expressed both receptor subtypes, TNF-R1 and TNF-R2, the activation of RhoA was predominantly via stimulation of the TNF-R1, although RhoA did not immunoprecipitate with the TNF-R1. In conclusion, the TNF-induced increase in the Ca(2+) sensitivity of MLC(20) phosphorylation is through stimulation of the TNF-R1 receptor and via a RhoA/Rho-kinase pathway leading to inhibition of the myosin light chain phosphatase. This intracellular mechanism may contribute to TNF-induced airway hyper-responsiveness.     

Receptor-independent activation of Rho-kinase-mediated calcium sensitisation in smooth muscle

1. The aim of this work was to determine whether Rho-kinase-mediated calcium sensitisation contributes to contractions of the mouse anococcygeus smooth muscle and, if so, whether the process was activated by receptor-dependent or receptor-independent mechanisms. 2. The Rho-kinase inhibitor Y27632 produced concentration-dependent decreases in tone raised by either the muscarinic receptor agonist carbachol (CCh), or the sarco-endoplasmic reticulum calcium ATPase inhibitor thapsigargin (Tg) (EC(50) values against CCh and Tg of 8.4+/-3.3 (n=6) and 6.1+/-2.1 (n=7) micro M, respectively). Pretreatment of tissues with Y27632 also inhibited contractions produced by 65 mM external potassium (69+/-7% (n=4) inhibition using 10 micro M Y27632). Y27632 had no effect on contractions produced by the inhibitor of smooth muscle myosin light-chain phosphatase, calyculin-A. 3. In beta-escin-permeabilised preparations, both CCh and Tg produced significant increases in tone over-and-above that produced by a combination of calcium (1 micro M) and GTP (100 micro M). These responses to CCh and Tg were inhibited by Y27632 (10 micro M). 4. Western blot analysis of fractionated tissue samples probed for RhoA immunoreactivity, indicated that both CCh and Tg were able to induce translocation of RhoA from the cytosol to the membrane. 5. These findings suggest that Rho-kinase-mediated calcium sensitisation is activated by both receptor-dependent and receptor-independent mechanisms in the mouse anococcygeus.     

色满卡林对自发性高血压大鼠血管平滑肌细胞凋亡的影响

目的：观察色满卡林对自发性高血压大鼠(SHR)血管平滑肌细胞(VSMCs)凋亡的影响。方法：30只12 wk龄SHR,随机分为高血压组、色满卡林组,另设正常对照组。色满卡林组给予色满卡林0.6 mg·kg~(-1)·d~(-1),分2次灌胃；另2组每日给予等量的生理盐水,共16 wk。监测尾动脉收缩压。用免疫组化法检测Bcl-2,Bax和PCNA蛋白表达。荧光标记TUNEL法检测VSMCs凋亡,计算VSMCs凋亡指数(SMAI)。结果：高血压组与正常对照组比较,收缩压明显增高(P＜0.05)；VSMCs中的Bcl-2,PCNA蛋白表达明显增强(P＜0.05)；SMAI明显减少(P＜0.01)；Bax蛋白表达2组间差异无显著意义(P＞0.05)。与高血压组比较,色满卡林组尾动脉收缩压呈降低趋势,但差别无显著意义(P＞0.05)；VSMCs的Bcl-2和PCNA蛋白的表达减少(P＜0.05),Bcl-2/Bax比值下降；SMAI增加(P＜0.05)。结论：色满卡林促进了SHR的VSMCs凋亡,可能机制是通过调节VSMCs的Bcl-2/Bax蛋白表达平衡。     

Increased Liver Uptake and Reduced Hepatic Stellate Cell Activation with a Cell-Specific Conjugate of the Rho-kinase Inhibitor Y27632

Purpose  

Rho-kinase regulates activation of hepatic stellate cells (HSC) during liver fibrosis, but the ubiquitous presence of this kinase may hinder examination of its exact role and the therapeutic use of inhibitors. We therefore coupled the Rho-kinase inhibitor Y27632 to a drug carrier that binds the mannose-6-phosphate insulin-like growth factor II (M6P/IGFII)-receptor which is upregulated on activated HSC.     

组织蛋白酶S抑制剂对兔血管平滑肌细胞凋亡的影响

目的 研究组织蛋白酶S抑制剂对培养的兔血管平滑肌细胞凋亡的影响及其机制.方法 获取兔主动脉组织,传代培养血管平滑肌细胞,将细胞分为对照组、单药组(血管紧张素Ⅱ)、联合组(组织蛋白酶S抑制剂+血管紧张素Ⅱ);采用流式细胞术和脱氧核糖核苷酸末端转移酶介导的缺口末端标记法(TUNEL)检测血管平滑肌细胞凋亡,蛋白质印迹法检测B细胞淋巴瘤基因-2蛋白、B细胞淋巴瘤基因-2相关蛋白X及半胱氨酸天冬氨酸特异性蛋白酶-3的表达.结果 ①流式细胞术检查及TUNEL染色结果均显示,联合组血管平滑肌细胞晚期凋亡数量明显低于单药组;TUNEL染色10 h和12 h时点,单药组与联合组差异有统计学意义[ 10 h:(23607±176)比(36058±269)个,12 b:(29813±205)比(39146±263)个,均P＜0.05];②蛋白质印迹检测结果显示,与单药组相比,联合组B细胞淋巴瘤基因-2相关蛋白X/B细胞淋巴瘤基因-2蛋白明显下降,组间差异有统计学意义(P＜0.05);联合组半胱氨酸天冬氨酸特异性蛋白酶-3表达明显降低,组间差异有统计学意义(P＜0.05).结论 组织蛋白酶S抑制剂可能通过下调B细胞淋巴瘤基因-2相关蛋白X、半胱氨酸天冬氨酸特异性蛋白酶-3表达减轻血管平滑肌细胞凋亡.     

JTE-013 mediates RhoA/ROCKl/Drpl signaling axis regulating mitochondrial damage and apoptosis to alleviate allergic rhinitis北大核心CSCD

目的探究JTE-013通过RhoA/ROCK1/Drp1通路调控线粒体损伤和凋亡对过敏性鼻炎(allergic rhinitis,AR)保护作用及机制。方法用卵清蛋白(OVA)建立小鼠AR模型。造模结束后,记录揉鼻、打喷嚏的次数。然后鼻组织切片进行HE、TUNEL和DHE染色。在体外,通过人重组白细胞介素-13(IL-13)刺激人鼻黏膜上皮细胞(HNEpCs),Western blot法检测JTE-013和Y27632对RhoA、ROCK1、Drp1及其相关磷酸化的蛋白和细胞凋亡相关蛋白表达影响。免疫荧光观察JTE-013和Y27632对细胞总ROS、线粒体膜电位和线粒体ROS生成,Drp1易位情况以及Cyt-c的表达情况。结果JTE-013减少了AR小鼠的揉鼻和打喷嚏频率,减轻鼻黏膜增厚并降低嗜酸细胞浸润。TUNEL和DHE染色结果提示,JTE-013可以抑制小鼠鼻上皮细胞凋亡并减少ROS表达。Western blot结果表明,JTE-013和Y27632都能明显降低RhoA、ROCK1、Drp1及p-Drp1(616),抑制凋亡蛋白Bax、cleaved-caspase-3、Cyt-c、cleaved-caspase-9表达并上调了p-Drp1(637)、Bcl-2表达。免疫荧光显示JTE-013或ROCK1的抑制剂几乎阻断了IL-13介导鼻黏膜上皮细胞ROS和mtROS生成增加、抑制了线粒体膜电位降低,阻滞了Cyt-c表达和Drp1易位。结论JTE-013能够通过抑制RhoA/ROCK1/Drp1信号轴调节线粒体的形态和功能,从而缓解AR小鼠鼻黏膜上皮细胞炎症。     

Protein kinases participate in the contraction in response to levobupivacaine in the rat aorta

Levobupivacaine is a long-acting amide local anesthetic that intrinsically produces vasoconstriction both in vivo and in vitro. Levobupivacaine increases intracellular calcium concentrations ([Ca(2+)](i)) in vascular smooth muscle cells. The goals of this in vitro study were to investigate whether levobupivacaine-induced contraction is associated with increased Ca(2+) sensitivity and to identify the protein kinases involved in mediating contraction in response to levobupivacaine in isolated rat aortic smooth muscle. The effect of levobupivacaine and potassium chloride (KCl) on the [Ca(2+)](i) and tension was measured simultaneously with acetoxymethyl ester of fura-2-loaded aortic strips. Cumulative levobupivacaine concentration-response curves were generated in the presence or absence of the following antagonists: GF 109203X; Y-27632; genistein; SP600125; PD 98059; and SB 203580. Levobupivacaine-induced protein kinase C (PKC), extracellular signal-regulated kinase (ERK), and c-Jun NH(2)-terminal kinase (JNK) phosphorylation and Rho-kinase (ROCK-2) membrane translocation were detected in rat aortic vascular smooth muscle cells using Western blotting. The slope of the [Ca(2+)](i)-tension curve for levobupivacaine was higher than that for KCl. Y-27632, GF 109203X, and SP600125 attenuated levobupivacaine-induced contraction in a concentration-dependent manner. Genistein, PD 98059, and SB 203580 attenuated levobupivacaine-induced contraction. Pretreatment with GF 109203X and Y-27632 inhibited levobupivacaine-induced PKC phosphorylation and Rho-kinase (ROCK-2) membrane translocation, respectively. Pretreatment with SP600125 or PD 98059 attenuated the levobupivacaine-induced phosphorylation of JNK and ERK, respectively. These results indicate that levobupivacaine-induced contraction involving an increase in myofilament Ca(2+) sensitivity involves the primary activation of Rho-kinase-, PKC-, and JNK-mediated pathways of rat aortic smooth muscle.     

Rho-kinase as a potential therapeutic target for the treatment of pulmonary hypertension

Pulmonary hypertension (PH) is a cardiovascular disorder characterized by vasoconstriction and vascular remodeling. Recently, rapidly increasing evidence from various rat models of PH and patients with PH suggest that small GTPase Rho and its downstream effector, Rho-kinase, play a key role in the pathogenesis of PH. Activation of the Rho/Rho-kinase pathway is important for pulmonary endothelial dysfunction, pulmonary vascular smooth muscle cell contractility, proliferation and apoptosis in PH. A greater Rho-kinase expression and an enhanced Rho-kinase activity have been observed in pulmonary arteries of PH rats, such as hypoxia-induced, monocrotaline-induced and genetic spontaneous PH rats. Moreover, Y-27632 or fasudil, the selective Rho-kinase inhibitors, significantly attenuated PH in various pulmonary hypertensive model rats and patients with PH, but did not reduce systemic blood pressure. Therefore, Rho-kinase inhibitors may have therapeutic potential for the treatment of PH.     

Growth factor-induced contraction of human bronchial smooth muscle is Rho-kinase-dependent

Growth factors have been implicated in the pathophysiology of asthma. However, the putative effects of these growth factors on human airway smooth muscle tone are still largely unknown. We performed contraction experiments using human bronchial smooth muscle ring preparations. The growth factor insulin-like growth factor-1 (IGF-1) induced a slowly developing sustained contraction, which was dependent on Rho-kinase, since contraction was almost completely inhibited by (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexane carboxamide (Y-27632; 1 microM). Angiotensin II, a G(q)-coupled receptor agonist which can act as a growth factor as well, induced a biphasic contraction, the sustained phase of which was also almost completely inhibited by Y-27632. We conclude that angiotensin II and IGF-1 induce a Rho-kinase-dependent sustained contraction of human bronchial smooth muscle. Since growth factors are associated with pathophysiological conditions such as asthma, inhibition of Rho-kinase could be effective under these conditions.     

Intracellular signal transduction modulating expression of plasminogen activator inhibitor-1 in adipocytes

The concentrations in blood of plasminogen activator inhibitor-1 (PAI-1), an inhibitor of fibrinolysis and proteolysis, are elevated in obese and insulin-resistant subjects, predispose them to the risk of thrombosis, and may accelerate atherogenesis. Adipose tissue is a prominent source. Accordingly, intracellular signaling pathways that may influence PAI-1 expression in adipocytes have been the focus of considerable study. Rho, a small GTP binding and GTPase protein, when activated in turn activates its target, Rho-associated coiled-coil forming protein, to yield an active kinase, Rho-kinase, an effector in the Rho pathway. Rho-kinase exerts calcium-sensitizing effects in vascular smooth muscle cells and inhibitory effects on transforming growth factor-beta (TGF-beta) expression in chicken embryonic heart cells. Because TGF-beta is a powerful agonist of PAI-1 expression, we characterized the effects of inhibition of Rho-kinase in 3T3-L1 adipocytes. PAI-1 mRNA was determined by Northern blotting, and PAI-1 protein was determined by Western blotting. The Rho-kinase inhibitor, Y-27632 [(R)-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide], increased PAI-1 expression markedly. Although genistein, a flavonoid tyrosine kinase, attenuated the increase of PAI-1 induced by Y-27632, other non-flavonoid tyrosine kinase inhibitors did not. However, another flavonoid, daidzein, which lacks tyrosine kinase activity, decreased basal PAI-1 expression and attenuated the induction of PAI-1 expression by Y-27632. Thus, the Rho/Rho-kinase system inhibits PAI-1 expression by a flavonoid-sensitive mechanism in adipocytes. Therefore, flavonoids may be useful in decreasing elevated PAI-1 expression in adipose tissue and its consequent pathophysiologic sequelae.     

Comparative pharmacological analysis of Rho-kinase inhibitors and identification of molecular components of Ca2+ sensitization in the rat lower urinary tract

We aimed to compare the expression and function of molecular components of the RhoA/Rho-kinase signaling pathway in the contractile responses of detrusor, trigonal and urethral smooth muscle, using selective Rho-kinase inhibitors. Contractility studies and molecular approaches were employed to demonstrate the expression patterns and functional activity of the RhoA/Rho-kinase signaling pathway in the lower urinary tract. Frequency-response curves (1-32 Hz) and concentration-response curves (CRC) to carbachol (CCh, 0.01-30 microM), phenylephrine (PE, 0.01-300 microM) and endothelin-1 (ET-1, 0.01-100 nM) were significantly attenuated (p<0.01) following incubation with the Rho-kinase inhibitors H-1152 (0.1-1 microM), Y-27632 (1-10 microM) or HA-1077 (10 microM). Addition of Rho-kinase inhibitors also markedly reduced (p<0.01) the contractions evoked by either KCl (80 mM) or alpha,beta-methylene ATP (alpha,beta-mATP, 10 microM). Among the Rho-kinase inhibitors tested, H-1152 was approximately 9-16 times more potent than Y-27632 or HA-1077. In addition, basal tone of detrusor and trigonal strips was reduced following addition of Y-27632 (10 microM), H-1152 (1 microM) and HA-1077 (10 microM). The expression of RhoA, RhoGDI, leukemia-associated RhoGEF (LARG) and p115RhoGEF was similar among the detrusor, trigone and urethra, whereas Rho-kinase alpha, Rho-kinase beta and PDZ-RhoGEF protein levels were significantly lower in the urethra. Components of the RhoA/Rho-kinase signaling are expressed in detrusor, trigonal and urethral smooth muscle and dynamically regulate contraction and tone. Manipulation of RhoGEF expression may provide further understanding of mechanisms involving Ca(2+) sensitization in the lower urinary tract.