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)

Cellular Prion Protein (PrPc) is a ubiquitous glycoprotein present on the surface of endothelial cells. Resting vascular endothelial cells show minimum expression of PrPc and can constitutively release PrPc. PrPc participates in cell survival, differentiation and angiogenesis. During development, neonatal brain endothelial cells transiently express PrPc. Our group recently reported upregulation of PrPc in microvessels from ischemic brain regions in stroke patients. Ischemia/hypoxia induces PrPc expression through the activation of extracellular signal-regulated kinase (ERK). All these data suggest that PrPc plays an important role in angiogenic responses. In addition, PrPc participates in cellular function in the central nervous system, since PrPc is also highly expressed in neurons. PrPc binds copper, suggesting a role in copper metabolism. PrPc also protects cells against oxidative stress and it seems to be involved in neuroprotection. Several studies have demonstrated that PrPc prevents cells from apoptosis and subsequent tissue damage. Moreover, PrPc plays an important role in the immune response. Here, we review the multiple functions of PrPc with a special attention to its recently reported role in angiogenesis.
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PMID:The normal cellular prion protein and its possible role in angiogenesis. 1850 75

Neurotrophins, such as the nerve growth factor (NGF), play an essential role in the growth, development, survival and functional maintenance of neurons in the central and peripheral systems. They also prevent neuronal cell death under various stressful conditions, such as ischemia and neurodegenerative disorders. NGF induces cell differentiation and neurite outgrowth by binding with and activating the NGF receptor tyrosine kinase followed by activation of a variety of signaling cascades. We have investigated the NGF-dependent neuritogenesis enhancer potential of a food-derived small molecule contained in Brassica vegetables and identified the protein tyrosine phosphatase (PTP) 1B as a key regulator of the NGF receptor-initiated signal transduction. Based on an extensive screening of Brassica vegetable extracts for the neuritogenic-promoting activity in the rat pheochromocytoma cell line PC12, we found the Japanese horseradish, wasabi (Wasabia japonica, syn. Eutrema wasabi), as the richest source and identified 6-methylsulfinylhexyl isothiocyanate (6-HITC), an analogue of sulforaphane isolated from broccoli, as one of the major neuritogenic enhancers in the wasabi. 6-HITC strongly enhanced the neurite outgrowth and neurofilament expression elicited by a low-concentration of NGF that alone was insufficient to induce neuronal differentiation. 6-HITC also facilitated the sustained-phosphorylation of the extracellular signal-regulated kinase and the autophosphorylation of the NGF receptor TrkA. It was found that PTP1B act as a phosphatase capable of dephosphorylating Tyr-490 of TrkA and was inactivated by 6-HITC in a redox-dependent manner. The identification of PTP1B as a regulator of NGF signaling may provide new clues about the chemoprotective potential of food components, such as isothiocyanates.
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PMID:A food-derived synergist of NGF signaling: identification of protein tyrosine phosphatase 1B as a key regulator of NGF receptor-initiated signal transduction. 1879 6

Fondaparinux is a synthetic pentasaccharide with powerful anticoagulant properties, which may also reduce ischemia-reperfusion (I/R) injury in vivo. However, the relative contributions of the anticoagulant and anti-inflammatory activities of fondaparinux to the observed protection are unknown. To address this issue, a crystalloid-perfused heart model was used to assess potential effects of fondaparinux on IR-induced heart injury in the absence of blood. Fondaparinux protects the ischemic myocardium independently of its haemostasis effects. Fondaparinux improved post ischemic myocardial contractile performance and tissue damage. These beneficial effects of fondaparinux may be related to the observed reduction in IR-induced oxidative stress and endothelial activation. In addition, fondaparinux altered NADPH oxidase activity and phosphorylated extracellular signal-regulated kinase (ERK) 1/2, suggesting activation of survival signaling pathways. The present study provides novel information by demonstrating that fondaparinux can attenuate inflammatory responses and oxidative stress in connection with IR heart injury. These findings could represent a potential therapeutic strategy for the prevention of myocardial dysfunction.
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PMID:The synthetic pentasaccharide fondaparinux prevents coronary microvascular injury and myocardial dysfunction in the ischemic heart. 1898 38

Delta-opioid receptor (DOR) is an oxygen-sensitive protein whose function in the rat retina is unknown. We examined whether DOR is involved in hypoxic preconditioning (HPC)-mediated retinoprotection following intraocular pressure (IOP) elevation. Rats were exposed to intermittent hypoxia (10% oxygen) to induce HPC. Unilateral retinal ischemia/reperfusion injury was induced by elevating IOP to 100 mmHg for 1 h. HPC attenuated the loss of neuronal marker expression and increased pro-apoptotic caspase 3 activity in the IOP retina. Excess superoxide production and 8-iso-prostaglandin F2alpha accumulation caused by enhanced oxidant protein expression and reduced antioxidant enzyme level after IOP elevation were largely abrogated by HPC. HPC markedly increased the expression of hypoxia-inducible factor-1alpha (HIF-1alpha) and DOR, but intravitreal administration of HIF-1alpha-specific small interfering RNA abrogated the up-regulation of DOR. This suggested that DOR functions downstream of HIF-1alpha. However, the endogenous content of leucine enkephalin in retinas was not affected by HPC or IOP. Treatment of retinas with the DOR antagonist naltrindole attenuated the HPC-induced protection and activation of extracellular signal-regulated kinase. These results suggest a novel mechanism of HPC-mediated retinoprotection whereby HIF-1alpha induces the expression of DOR, and DOR-mediated activation of extracellular signal-regulated kinase triggers cellular events that correct the redox imbalance in the post-ischemic retina.
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PMID:Novel role for the delta-opioid receptor in hypoxic preconditioning in rat retinas. 1905 76

Preconditioning is abolished in the prediabetic Zucker obese rat. It has been shown that prevention of mitochondrial permeability transition pore (mPTP) opening is involved in preconditioning by the noble gas helium. Here, we investigated: 1) whether helium induces pre- and postconditioning in Zucker rats and 2) whether possible regulators of the mPTP [i.e., mitochondrial respiration or the extracellular signal-regulated kinase (Erk) 1/2, Akt/glycogen synthase kinase (GSK)-3beta signaling pathway] are influenced. Anesthetized Zucker lean (ZL) and Zucker obese (ZO) rats were randomized to seven groups. Control animals were not treated (ZL-/ZO-Con). Preconditioning groups (ZL-/ZO-He-PC) inhaled 70% helium for 3 x 5 or 6 x 5 min, and postconditioning groups (ZL-/ZO-He-PostC) inhaled 70% helium for 15 min at the onset of reperfusion. Animals underwent 25 min of ischemia and 120 min of reperfusion. In additional experiments, hearts were excised after the third helium exposure for analysis of mitochondrial respiration and for Western blot analysis of Erk1/2, Akt, and GSK-3beta phosphorylation. Helium reduced infarct size from 52 +/- 3% (mean +/- S.E.) to 32 +/- 2% and 37 +/- 2% in ZL rats (ZL-HE-PC, ZL-He-PostC), respectively, but not in ZO rats [ZO-He-PC, 56 +/- 3%; ZO-He-PC (6x), 57 +/- 4%; and ZO-He-PostC, 51 +/- 3% versus ZO-Con, 54 +/- 3%]. Mitochondrial respiration analysis showed that helium causes mild uncoupling in ZL rats (2.27 +/- 0.03 versus 2.51 +/- 0.03) but not in ZO rats (2.52 +/- 0.04 versus 2.52 +/- 0.03). Helium had no effect on Erk1/2 and Akt phosphorylation. GSK-3beta phosphorylation during ischemia was reduced after helium application in ZL but not in ZO rats. Helium-induced preconditioning is abolished in obese Zucker rats in vivo, probably caused by a diminished effect of helium on mitochondrial respiration.
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PMID:Helium-induced early preconditioning and postconditioning are abolished in obese Zucker rats in vivo. 1924 49

Extracellular acidification is a hallmark of a number of debilitating pathologies including cancer, ischemia and inflammation. We have recently shown that in human granule precursor tumour cells a fall in extracellular pH triggers increases in intracellular Ca(2+) concentration through activation of G-protein coupled proton-sensing receptors coupling to phospholipase C. This pH-dependent rise in cytosolic Ca(2+) led to activation of the extracellular signal-regulated kinase ERK, providing a mechanistic explanation of how extracellular acidification can promote tumour growth. We now find that differentiation of granule precursor tumour cells profoundly affects their ability to respond to extracellular acidification with gene transcription. Differentiating cells have a lower Ca(2+) release probability from intracellular Ca(2+) stores upon acidification and cells that respond have a significantly smaller and slower Ca(2+) signal than proliferating cells. Importantly, Ca(2+) release in differentiating cells fails to evoke ERK phosphorylation. This altered responsiveness of differentiating cells is not due to reduced proton-sensing receptor expression or diminished Ca(2+) store content. Rather, our results suggest that in differentiating cells, the proton-sensing receptor couples less effectively to phospholipase C activation and IP(3) formation. Hence, the ability of human granule cells to respond to extracellular acidification by generating Ca(2+) signals and ERK activation is state-dependent, being lost upon differentiation.
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PMID:Differentiation impairs low pH-induced Ca2+ signaling and ERK phosphorylation in granule precursor tumour cells. 1924 96

Ischemia/reperfusion injury (IRI) induces an innate immune response, leading to an inflammatory reaction and tissue damage that have been attributed to engagement of the Toll-like receptor (TLR) 2 and 4. However, the respective roles of TLR2 and/or TLR4 in mediating downstream activation of mitogen-activated protein kinase (MAPK) pathways during IRI have not been fully elucidated. Here we show that extracellular signal-regulated kinase (ERK)1/2 is activated in both intact kidneys and cultured renal tubule epithelial cells (RTECs) from wildtype and Tlr4 knockout mice, but not those from Tlr2 knockout mice subjected to transient ischemia. Geldanamycin (GA), an inhibitor of heat shock protein 90 and reticulum endoplasmic-resident gp96, and gp96 mRNA silencing (siRNA), did not affect ERK1/2 activation in either post-hypoxic wild-type or Tlr4-deficient RTECs, but did restore its activation in post-hypoxic Tlr2-deficient RTECs. Immunoprecipitation studies revealed that gp96 co-immunoprecipitates with the serine-threonine protein phosphatase 5 (PP5), identified as a negative modulator of the mitogen extracellular kinase (MEK)-ERK pathway, in unstressed wild-type and post-hypoxic Tlr2-deficient RTECs. In contrast, PP5 co-immunoprecipitation with gp96 was strikingly reduced in post-hypoxic wild-type RTECs, suggesting that the inactivation of PP5 resulting from the dissociation of PP5 from gp96 allows the activation of ERK1/2 to occur. Inhibition of PP5 by okadaic acid, and Pp5 siRNA also restored TLR2-mediated phosphorylation of ERK1/2, and apoptosis signal-regulating kinase 1 (ASK1)/c-Jun N-terminal kinase (JNK)-mediated apoptosis in post-hypoxic Tlr2-deficient RTECs. These findings indicate that gp96 interacts with PP5 and controls TLR2-mediated induction of ERK1/2 in post-hypoxic renal tubule cells.
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PMID:Heat shock protein gp96 interacts with protein phosphatase 5 and controls toll-like receptor 2 (TLR2)-mediated activation of extracellular signal-regulated kinase (ERK) 1/2 in post-hypoxic kidney cells. 1926 98

It has been reported that icariin protects neurons against ischemia/reperfusion injury. In this study, we found that icariin could enhance neuronal viability and suppress neuronal death after oxygen and glucose deprivation (OGD). Further study showed that neuroprotection by icariin was through the induction of Sirtuin type 1 (SIRT1), an effect that was reversed by SIRT1 inhibitor III and P38 inhibitor SB203580. SIRT1 is an endogenous gene of longevity, which increased neuronal viability and could be activated by stimulating the mitogen-activated protein kinase (MAPK) pathway. However, this study found that icariin activated the MAPK/P38 pathway, not the extracellular signal-regulated kinase (MAPK/ERK) or c-Jun N-terminal protein kinase (MAPK/JNK) to regulate SIRT1 expression. The results suggest that icariin may be developed into a neuroprotectant for ischemia-related brain injury.
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PMID:Icariin enhances neuronal survival after oxygen and glucose deprivation by increasing SIRT1. 1930 70

Improving endothelial nitric oxide synthase (eNOS) bioactivity and endothelial function is important to limit native, vein graft, and transplant atherosclerosis. Visfatin, a NAD biosynthetic enzyme, regulates the activity of the cellular survival factor, Sirt1. We hypothesized that visfatin may improve eNOS expression, endothelial function, and postnatal angiogenesis. In human umbilical vein (HUVEC) and coronary artery endothelial cells, we evaluated the effects of recombinant human visfatin on eNOS protein and transcript expression and mRNA stability, in the presence and absence of visfatin RNA silencing. We also assessed visfatin-induced protein kinase B (Akt) activation and its association with src-tyrosine kinases, phosphorylation of Ser(1177) within eNOS in the presence and absence of phosphatidylinositol 3-kinase (PI 3-kinase) inhibition with LY-294002, and evaluated the contributory role of extracellular signal-regulated kinase 1/2. Finally, we determined the impact of visfatin on HUVEC migration, proliferation, inflammation-induced permeability, and in vivo angiogenesis. Visfatin (100 ng/ml) upregulated and stabilized eNOS mRNA and increased the production of nitric oxide and cGMP. Visfatin-treated HUVEC demonstrated greater proliferation, migration, and capillary-like tube formation but less tumor necrosis factor-alpha-induced permeability; these effects were decreased in visfatin gene-silenced cells. Visfatin increased total Akt and Ser(473)-phospho-Akt expression with concomitant rises in eNOS phosphorylation at Ser(1177); these effects were blocked by LY-2940002. Studies with PP2 showed that the nonreceptor tyrosine kinase, src, is an upstream stimulator of the PI 3-kinase-Akt pathway. Visfatin also activated mitogen-activated protein (MAP) kinase through PI 3-kinase, and mitogen/extracellular signal-regulated kinase inhibition attenuated visfatin-elicited Akt and eNOS phosphorylation. Visfatin-filled Matrigel implants showed an elevated number of infiltrating vessels, and visfatin treatment produced significant recovery of limb perfusion following hindlimb ischemia. These results indicate a novel effect of visfatin to stimulate eNOS expression and function in endothelial cells, via a common upstream, src-mediated signaling cascade, which leads to activation of Akt and MAP kinases. Visfatin represents a translational target to limit endothelial dysfunction, native, vein graft and transplant atherosclerosis, and improve postnatal angiogenesis.
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PMID:Visfatin activates eNOS via Akt and MAP kinases and improves endothelial cell function and angiogenesis in vitro and in vivo: translational implications for atherosclerosis. 1935 6

Oxidative injury contributes to neuronal degeneration in many central nervous system (CNS) diseases, such as Parkinson's disease, Alzheimer's disease, epilepsy and ischemia. Inducible heme oxygenase (HO)-1 acts against oxidants that are thought to play a role in the pathogenesis of these diseases. Lindenenyl acetate, isolated by bioassay-guided fractionation of the MeOH extract of the roots of Lindera strychnifolia, showed potent neuroprotective effects on glutamate-induced neurotoxicity by inducing the expression of HO-1 and increasing the activity of HO in mouse hippocampal HT22 cells. Furthermore, lindenenyl acetate caused the nuclear accumulation of nuclear factor-E2-related factor 2 (Nrf2) and increased the promoter activity of antioxidant response elements (ARE) in mouse hippocampal HT22 cells. In addition, we found that treatment of the cells with extracellular signal-regulated kinase (ERK) inhibitor (U0126) reduced lindenenyl acetate-induced HO-1 expression. Lindenenyl acetate also increased ERK phosphorylation. These results suggest that lindenenyl acetate increases cellular resistance to glutamate-induced oxidative injury in mouse hippocampal HT22 cells, presumably through the ERK pathway-Nrf2/ARE-dependent HO-1 expression.
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PMID:Cytoprotective effects of lindenenyl acetate isolated from Lindera strychnifolia on mouse hippocampal HT22 cells. 1944 2


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