Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The small G protein RhoA and its downstream effector Rho-kinase/ROCK2 play an important role in regulation of various vasculature cellular functions. Nitric oxide (NO) produced by endothelial NO synthase (eNOS) is an important mediator of vascular homeostasis and cerebral blood flow. Using the human endothelial cell line HUVEC, the present study investigated the role of RhoA and Rho-kinase in endothelial eNOS protein expression under hypoxic conditions as an in vitro model of ischemia. RhoA protein levels in HUVEC were low under normoxic conditions, but were significantly increased after 5h of hypoxia. Endothelial Rho-kinase expression was not detected until after 3h of hypoxia; such expression remained significantly increased after 5h. On the other hand, endothelial eNOS expression was similar after 3h of hypoxia, but was significantly decreased after 5h. The hypoxia-induced decrease in eNOS expression was significantly enhanced by expression of the constitutively active form of RhoA and significantly inhibited by suppression of RhoA expression by small interfering RNA. The hypoxia-induced decrease in eNOS expression was significantly inhibited when endogenous Rho-kinase activation was inhibited by Rho-binding domain expression. Furthermore, the hypoxia-induced decrease in eNOS expression was significantly enhanced by expression of the constitutively active form of Rho-kinase. Since expression and activation of RhoA and Rho-kinase inhibit eNOS expression in endothelial cells, attempts to down-regulate RhoA and Rho-kinase by multiple drugs, such as statins or Rho-kinase inhibitors, might provide endothelial and cardiovascular benefits through upregulation of eNOS.
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PMID:Hypoxia-induced upregulation of endothelial small G protein RhoA and Rho-kinase/ROCK2 inhibits eNOS expression. 1699 86

Rho-kinase is a serine threonine kinase that increases vasomotor tone via its effects on both endothelium and smooth muscle. Rho-kinase inhibition reduces cerebral infarct size in wild type, but not endothelial nitric oxide synthase deficient (eNOS-/-) mice. The mechanism may be related to Rho-kinase activation under hypoxic/ischemic conditions and impaired vasodilation because of downregulation of eNOS activity. To further implicate Rho-kinase in impaired vascular relaxation during hypoxia/ischemia, we exposed isolated vessels from rat and mouse to 60 mins of hypoxia, and showed that hypoxia reversibly abolished acetylcholine-induced eNOS-dependent relaxation, and that Rho-kinase inhibitor hydroxyfasudil partially preserved this relaxation during hypoxia. We, therefore, hypothesized that if hypoxia-induced Rho-kinase activation acutely impairs vasodilation in ischemic cortex, in vivo, then Rho-kinase inhibitors would acutely augment cerebral blood flow (CBF) as a mechanism by which they reduce infarct size. To test this, we studied the acute cerebral hemodynamic effects of Rho-kinase inhibitors in ischemic core and penumbra during distal middle cerebral artery occlusion (dMCAO) in wild-type and eNOS-/- mice using laser speckle flowmetry. When administered 60 mins before or immediately after dMCAO, Rho-kinase inhibitors hydroxyfasudil and Y-27632 reduced the area of severely ischemic cortex. However, hydroxyfasudil did not reduce the area of CBF deficit in eNOS-/- mice, suggesting that its effect on CBF within the ischemic cortex is primarily endothelium-dependent, and not mediated by its direct vasodilator effect on vascular smooth muscle. Our results suggest that Rho-kinase negatively regulates eNOS activity in acutely ischemic brain, thereby worsening the CBF deficit. Therefore, rapid nontranscriptional upregulation of eNOS activity by small molecule inhibitors of Rho-kinase may be a viable therapeutic approach in acute stroke.
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PMID:Rho-kinase inhibition acutely augments blood flow in focal cerebral ischemia via endothelial mechanisms. 1703 91

The neuroprotective potential and therapeutic time window for fasudil, a Rho-kinase inhibitor (RKI), were evaluated for delayed neuronal death in gerbils. A preliminary screening was done on fasudil, ozagrel, and edaravone using a single administration in a delayed neuronal death study. Intraperitoneal (i.p.) administration of edaravone, a free radical scavenger (3, 10 mg/kg) immediately after re-circulation did not reduce neuronal degeneration. We previously reported that ozagrel, a thromboxane A(2) synthetase inhibitor (30 mg/kg) also did not reduce neuronal degeneration, while fasudil (3, 30 mg/kg) significantly protected against the ischemia-induced neuronal loss. To clarify the therapeutic time window of fasudil, which showed a positive effect in a preliminary screening, animals received their first i.p. administration of fasudil (10 mg/kg) 24 or 48 h after ischemia. Administration of fasudil twice daily was continued until day 6. Fasudil significantly protected against the ischemia-induced delayed neuronal death when the treatment was started 24 h after ischemia. In gerbils, hydroxyfasudil, an active metabolite of fasudil, was found following an i.p. administration of fasudil (10 mg/kg), and the value of the area under the plasma level curve of hydroxyfasudil was 7 times higher than that of fasudil. Hydroxyfasudil may contribute to the potency of fasudil. The present findings indicate that the RKI fasudil reduces ischemic neuronal damage with a wide therapeutic time window in gerbil, and may be useful in the treatment of acute ischemic stroke in humans.
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PMID:Wide therapeutic time window for fasudil neuroprotection against ischemia-induced delayed neuronal death in gerbils. 1712 88

Rho-kinase has been identified as one of the effectors of the small GTP-binding protein Rho. Accumulating evidence has demonstrated that the Rho/Rho-kinase pathway plays an important role in various cellular functions, not only in vascular smooth muscle cell (VSMC) contraction but also in VSMC proliferation, cell migration, and gene expression. Two isoforms of Rho-kinase encoded by two different genes have been identified: ROCK1 and ROCK2. These isoforms are ubiquitously expressed, but with preferential expression of ROCK2 in the brain and skeletal muscle. The expression of Rho-kinase itself is mediated by the protein kinase C/NF-kappaB pathway with an inhibitory and stimulatory modulation by estrogen and nicotine, respectively. At the cellular level, Rho-kinase mediates VSMC contraction, stimulates VSMC proliferation and migration, and enhances inflammatory cell motility. Rho-kinase also upregulates various molecules that accelerate inflammation/oxidative stress, thrombus formation, and fibrosis, while it downregulates endothelial nitric oxide synthase and inhibits insulin signaling. Rho-kinase activity regulates major morphogenetic events during embryonic development through cell migration, differentiation, and axis formation. In animal and clinical studies, Rho-kinase has been shown to be substantially involved in the pathogenesis of vasospasm, arteriosclerosis, hypertension, pulmonary hypertension, and ischemia/reperfusion injury. Fasudil, a selective Rho-kinase inhibitor developed in Japan, is effective for the treatment of a wide range of cardiovascular diseases, with reasonable safety. Thus Rho-kinase is an important therapeutic target in cardiovascular medicine. This review summarizes the recent progress in the study of Rho-kinase and addresses future perspectives of Rho-kinase inhibitors.
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PMID:Progress of the study of rho-kinase and future perspective of the inhibitor. 1732 36

Excitotoxic neuronal death contributes to many neurological disorders, and involves calcium influx and stress-activated protein kinases (SAPKs) such as p38alpha. There is indirect evidence that the small Rho-family GTPases Rac and cdc42 are involved in neuronal death subsequent to the withdrawal of nerve growth factor (NGF), whereas Rho is involved in the inhibition of neurite regeneration and the release of the amyloidogenic Abeta(42) peptide. Here we show that Rho is activated in rat neurons by conditions that elevate intracellular calcium and in the mouse cerebral cortex during ischemia. Rho is required for the rapid glutamate-induced activation of p38alpha and ensuing neuronal death. The ability of RhoA to activate p38alpha was not expected, and it was specific to primary neuronal cultures. The expression of active RhoA alone not only activated p38alpha but also induced neuronal death that was sensitive to the anti-apoptotic protein Bcl-2, showing that RhoA was sufficient to induce the excitotoxic pathway. Therefore, Rho is an essential component of the excitotoxic cell death pathway.
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PMID:Rho mediates calcium-dependent activation of p38alpha and subsequent excitotoxic cell death. 1736 26

Microcirculatory disturbances contribute to the expansion of infarct lesions after focal cerebral ischemia. Recently, it was shown that Rho-kinase involves in endothelial dysfunction via down-regulation of endothelial nitric oxide synthase function in a rodent stroke model. However, it is not clear whether endothelial Rho-kinase is activated in vivo or Rho-kinase activation contributes to microcirculatory disturbances after cerebral ischemia. In this study, we assessed the temporal and spatial profiles of Rho-kianse activity and the effect of the Rho-kinase inhibitor fasudil on microcirculatory disturbances in the focal brain ischemia. Rho-kinase activation was evaluated by analyzing the phosphorylation of adducin, a substrate of Rho-kinase, by immunohistochemistry. Staining for p-adducin was found in endothelia in the ischemic area 6 hr after induction of ischemia. Microcirculatory disturbances and increased endothelial cell staining for von Willebrand factor (vWF) were observed in the same area. Postischemic treatment with fasudil suppressed endothelial Rho-kinase activation, preserved microcirculation, and inhibited endothelial cell vWF staining. These effects resulted in inhibition of infarct expansion and improvement of neurologic deficits. These findings indicate that Rho-kinase is activated in the endothelial cells and contributes to microcirculatory disturbances in cerebral ischemia. The vascular protective effect of Rho-kinase inhibitors may be useful in the treatment of the acute phase of ischemic stroke.
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PMID:Rho-kinase activation in endothelial cells contributes to expansion of infarction after focal cerebral ischemia. 1752 23

(1) The role of activation of Rho-kinase in the pathogenesis of cognitive deficit and neuronal damage caused by chronic global ischemia is not clear. In this study, hydroxyfasudil, a Rho-kinase inhibitor, was found to improve the learning and memory performance significantly in rats with ischemia induced by chronic cerebral hypoperfusion after permanent bilateral carotid artery ligation (BCAL). This was observed by the administration of hydroxyfasudil (1 mg/kg or 10 mg/kg, once per day for 30 days) to ischemic rats and the measurements of escape latency and time spent in the target quadrant among the ischemic, sham, and ischemic plus hydroxyfasudil rats by the method of Morris water maze. (2) In electrophysiological study, hydroxyfasudil abolished the inhibition of long-term potentiation (LTP) in rats with ischemia. Morphologically, it also markedly reduced pathological changes such as neuronal cells loss and nuclei shrinkage in cortex and hippocampus of ischemic rats. Biochemical analysis showed that the inhibition of Rho-kinase by hydroxyfasudil reduced the amount of MDA and increased the activities of SOD and GPx in ischemic rats that had increased MDA and decreased SOD and GPx activities. (3) To explore mechanism (s) of the beneficial effects of hydroxyfasudil in ischemia, we performed immunohistochemistry and RT-PCR analyses of NMDA NR2B subunit and for the first time found that hydroxyfasudil increased the expression of NR2B in cortex and hippocampus at both protein and mRNA levels. (4) Taken together, our data further support the notion that the inhibition of Rho-kinase provides neuroprotective effects in cerebral ischemia.
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PMID:Improvement of cognitive deficit and neuronal damage in rats with chronic cerebral ischemia via relative long-term inhibition of rho-kinase. 1755 19

In the transplant surgery, reactive oxygen species (ROS) from the reperfused tissue cause ischemia-reperfusion injury, resulting in the primary graft failure. We have recently reported that Rho-kinase, an effecter of the small GTPase Rho, plays an important role in the ROS production in the hyperacute phase of reperfusion; however, the sources and mechanisms of the ROS production remain to be elucidated. The aim of this study was to investigate the source of ROS production with a special reference to Rho-kinase to develop a new strategy against ischemia-reperfusion injury. In an in vivo rat model of liver transplantation, Kupffer cells in the graft were depleted using liposome-encapsulated dichloromethylene diphosphonate to examine the source of ROS production. The effect of adenoviral-mediated overexpression of a dominant-negative Rho-kinase (AdDNRhoK) in hepatocytes in the graft was also examined. Kupffer cells were not involved in the ROS production, whereas the AdDNRhoK transfection to hepatocytes significantly suppressed the ROS production. Furthermore, the ROS production was dose-dependently inhibited by apocynin, an NADPH oxidase inhibitor. Expression of DNRhoK also suppressed the release of pro-inflammatory cytokines, and ameliorated the lethal liver injury with a significant prolongation of the survival. These results suggest that the Rho-kinase-mediated pathway plays a crucial role in the ROS production through NADPH oxidase in hepatocytes during the hyperacute phase of reperfusion in vivo. Thus, Rho-kinase in hepatocytes may be a new therapeutic target for the prevention of primary graft failure in liver transplantation.
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PMID:Rho-kinase as a novel gene therapeutic target in treatment of cold ischemia/reperfusion-induced acute lethal liver injury: effect on hepatocellular NADPH oxidase system. 1767 9

A protective effect of Rho-kinase inhibitor on various organ injuries is gaining attention. Regarding liver injury, Rho-kinase inhibitor is reported to prevent carbon tetrachloride (CCl4)- or dimethylnitrosamine-induced liver fibrosis and hepatic ischemia-reperfusion injury in rats. Because Rho-kinase inhibitor not only improved liver fibrosis but also reduced serum alanine aminotransferase (ALT) level in CCl4-induced liver fibrosis, we wondered whether Rho-kinase inhibitor might exert a direct hepatocyte-protective effect. We examined this possibility in acute CCl4 intoxication in rats. Rho-kinase inhibitor, HA-1077, reduced serum alanine ALT level in rats with acute liver injury induced by CCl4 with the improvement of histological damage and the reduction of the number of apoptotic cells. In cultured rat hepatocytes in serum-free condition, HA-1077 reduced apoptosis evaluated by quantitative determination of cytoplasmic histone-associated DNA oligonucleosome fragments with the reduction of caspase-3 activity and the enhancement of Bcl-2 expression. HA-1077 stimulated phosphorylation of Akt, and wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3-kinase)/Akt pathway, abrogated the reduction of hepatocyte apoptosis by HA-1077 in vitro. Furthermore, wortmannin abrogated the reduction of serum ALT level by HA-1077 in rats with acute liver injury induced by CCl4, suggesting that the activation of PI3-kinase/Akt pathway may be involved in the hepatocyte-protective effect by Rho-kinase inhibitor in vivo. In conclusion, Rho-kinase inhibitor prevented hepatocyte damage in acute liver injury induced by CCl4 in rats and merits consideration as a hepatocyte-protective agent in liver injury, considering its direct antiapoptotic effect on hepatocytes in vitro.
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PMID:Rho-kinase inhibitor prevents hepatocyte damage in acute liver injury induced by carbon tetrachloride in rats. 1776 35

HIF-1alpha is the inducible subunit of the dimeric transcription factor HIF-1 (Hypoxia Inducible Factor 1). It is induced by hypoxia and hypoxia-mimetics in most cell types, as well as non-hypoxic signals such as growth factors, cytokines and oncogenes, often in a cell specific manner. HIF-1 is present in virtually all cells of higher eukaryotes and its function is of great biomedical relevance since it is highly involved in development, tumor progression and tissue ischemia. Intracellular signaling to HIF-1alpha, as well as its further action, involves its participation in numerous protein complexes. Using the yeast two-hybrid system we have identified MgcRacGAP (male germ cell Rac GTPase Activating Protein) as a HIF-1alpha interacting protein. The MgcRacGAP protein is a regulator of Rho proteins, which are principally involved in cytoskeletal organization. We have verified specific binding of HIF-1alpha and MgcRacGAP in vitro and in vivo in mammalian cells. We have additionally shown that MgcRacGAP overexpression inhibits HIF-1alpha transcriptional activity, without lowering HIF-1alpha protein levels, or altering its subcellular localization. Moreover, this inhibition is dependent on the MgcRacGAP domain that interacts with HIF-1alpha. In conclusion, our findings demonstrate that HIF-1alpha function is negatively affected by its interaction with MgcRacGAP.
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PMID:MgcRacGAP interacts with HIF-1alpha and regulates its transcriptional activity. 1798 82


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