Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HIF-1 is the main transcription factor responsible for increased gene expression in hypoxia: VEGF, erythropoietin, GLUT-1, and glycolytic enzymes are such target genes and all participate in the adaptative response of cells to hypoxia. AP-1 activation by hypoxia has also been demonstrated in several cell lines and it cooperates with HIF-1 for increasing VEGF gene transcription in hypoxia. Both HIF-1 and AP-1 activation by hypoxia seems to involve members of the MAP kinase family. Here, we summarize the data indicating that ERK and JNK are needed for activation of HIF-1 and AP-1, respectively.
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PMID:HIF-1 and AP-1 cooperate to increase gene expression in hypoxia: role of MAP kinases. 1179 93

Oxygen-dependent regulation of HIF-1 activity occurs at multiple levels in vivo. The mechanisms regulating HIF-1alpha protein expression have been most extensively analyzed but the ones modulating HIF-1 transcriptional activity remain unclear. Changes in the phosphorylation and/or redox status of HIF-1alpha certainly play a role. Here, we show that ionomycin could activate HIF-1 transcriptional activity in a way that was additive to the effect of hypoxia without affecting HIF-1alpha protein level. In addition, a calmodulin dominant negative mutant and W7, a calmodulin antagonist, as well as BAPTA, an intracellular calcium chelator, inhibited the hypoxia-induced HIF-1 activation. These results indicate that elevated calcium in hypoxia could participate in HIF-1 activation. Furthermore, ERK but not JNK phosphorylation was evidenced in both conditions, ionomycin and hypoxia. PD98059, an inhibitor of the ERK pathway as well as a ERK1 dominant negative mutant also blocked HIF-1 activation by hypoxia and by ionomycin. A MEKK1 (a kinase upstream of JNK) dominant negative mutant had no effect. In addition, BAPTA, calmidazolium, a calmodulin antagonist and PD98059 inhibited VEGF secretion by hypoxic HepG2. All together, these results suggest that calcium and calmodulin would act upstream of ERK in the hypoxia signal transduction pathway.
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PMID:Role of ERK and calcium in the hypoxia-induced activation of HIF-1. 1244 87

Angiogenesis is required for the development and biologic progression of infiltrative astrocytomas and takes the form of "microvascular hyperplasia" in glioblastoma multiforme, the most malignant astrocytoma. This pathologic term refers to an abnormal vascular proliferation that is often associated with necrosis and likely originates in hypoxic zones. Both the physiologic response to hypoxia and genetic alterations contribute to this process. The presence of hypoxic regions within an expanding tumor mass leads to upregulation of pro-angiogenic factors, such as vascular endothelial growth factor (VEGF), through increased activity of the transcriptional complex HIF-1 (hypoxia-inducible factor-1). HIF-1 mediated gene expression may be directly or indirectly modulated by alterations in oncogenes/tumor suppressor genes that occur during astrocytoma development, including PTEN, TP53, p16(CDKN2A), p14ARF, EGFR, and PDGFR. Genetic alterations are also believed to influence the HIF-independent expression of pro- and anti- angiogenic factors, such as basic fibroblast growth factor (bFGF) and thrombospondin-1 (TSP-1), respectively. Thus, genetic events that occur during the progression of infiltrating astrocytomas promote angiogenesis, both by modulating hypoxia induced gene expression and by regulating of pro- and anti- angiogenic factors.
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PMID:Genetic modulation of hypoxia induced gene expression and angiogenesis: relevance to brain tumors. 1245 39

HIF-1 (hypoxia-inducible factor-1) is the main transcription factor responsible for increased gene expression in hypoxia. The oxygen-dependent regulation of HIF-1 activity occurs at multiple levels in vivo. The mechanisms regulating HIF-1alpha protein expression have been most extensively analyzed, but the ones modulating HIF-1 transcriptional activity remain unclear. Changes in the phosphorylation and/or redox status of HIF-1alpha certainly play a role. Here, we show that ionomycin could activate HIF-1 transcriptional activity in a way that is additive to the effect of hypoxia without affecting HIF-1alpha protein level and HIF-1 DNA binding capacity. In addition, a calmodulin dominant-negative mutant as well as BAPTA, an intracellular calcium chelator, inhibited the hypoxia-induced HIF-1 activation. These results indicate that elevated calcium in hypoxia could participate in HIF-1 activation. PD98059, an inhibitor of the ERK pathway, but not KN-93, an inhibitor of calmodulin kinases II and IV, also blocked HIF-1 activation by hypoxia and by ionomycin. Altogether, these results suggest that calcium and calmodulin would act upstream of ERK in the hypoxia signal transduction pathway leading to enhanced HIF-1 transcriptional activity.
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PMID:ERK and calcium in activation of HIF-1. 1248 9

Mitogen-activated protein kinases (MAPKs) and protein kinase B (PKB) mediate growth and stress signals and have been implicated in the hypoxic response. Under hypoxic conditions, the expression of plasminogen activator inhibitor-1 (PAI-1) is mainly controlled by the hypoxia-inducible factor HIF-1. However, the role of MAPKs and PKB in HIF-1-mediated PAI-1 regulation is not clear. Treatment with the p38 inhibitor SB203580 and the PI3K inhibitor LY294002, but not with the MEK1 inhibitor PD98059, abrogated hypoxia-dependent PAI-1 induction in HepG2 cells. Consistently, overexpression of PKB or of the p38 upstream kinases MKK6 and MKK3 and of JNK, but not of ERK, enhanced PAI-1 mRNA levels. In MKK3-, MKK6- and PKB-expressing cells luciferase (Luc) activities from a hypoxia-inducible PAI-1-Luc construct or from a HIF-dependent Luc construct and, concomitantly, HIF-1alpha protein levels were enhanced. These findings indicate that p38- and PKB-dependent signalling pathways contribute to enhanced PAI-1 levels in the hypoxic response.
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PMID:Regulation of the hypoxia-dependent plasminogen activator inhibitor 1 expression by MAP kinases. 1266 21

The type-I plasminogen activator inhibitor (PAI-1), the primary inhibitor of both tissue-type and urokinase-type plasminogen activators (t-PA, u-PA), is the primary regulator of plasminogen activation and possibly of extracellular proteolysis. In anchorage-dependent cells, the PAI-1 gene is regulated by cell adhesion. PAI-1 gene expression is induced more evidently in cells that adhered to the culture plate than in those that did not adhere. In this study, we further demonstrate that the PAI-1 gene expression associated with cell adhesion is elicited through the activation of MEK and p42/p44 mitogen-activated protein (MAP) kinase (MAPK; ERK) signal pathways. We found that the MEK inhibitors, PD98059 and U0126, inhibited the induction of PAI-1 gene and protein expression during cell adhesion, PD98059 also inhibited the adhesion of cells to the culture plate, and cell adhesion elicited the kinase activities of MEK and ERK. In addition, we illustrate that two transcription response elements, the serum response element (SRE) and the hypoxia response element (HRE), which exist in the PAI-1 promoter, might be correlated with PAI-1 gene expression during cell adhesion. We discovered that the binding ability of nucleoproteins to both SRE and HRE was enhanced by cell adhesion and was dependent on MEK. Based on these results, we suggest that both MEK and ERK are involved in the induction of PAI-1 gene expression during cell adhesion. Furthermore, the subsequent downstream molecules, Elk-1 and HIF-1, may also participate.
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PMID:The plasminogen activator inhibitor-1 gene is induced by cell adhesion through the MEK/ERK pathway. 1463 Nov 13

In the last three decades, numerous reports have shown that patients with chronic pulmonary disease and with heart failure with hypoxemia cleared drugs at a lower rate than healthy volunteers. As a consequence decreased clearance, drug toxicity is frequent in these patients. The reduction in drug clearance is due to a decrease in activity of cytochrome P450 isoforms, partly associated to the hypoxemia. With in vivo animal models, acute moderate hypoxia (PaO2 of around 35-50 mm Hg) reduces the clearance of drugs biotransformed by CYP1A1, CYP1A2, CYP2B6, CYP2C9, CYP2C19 and CYP2E1, although hypoxia does not affect the clearance of drugs biotransformed by CYP3A6. Ex vivo and in vitro experiments demonstrate that hypoxia down-regulates CYP1A1, CYP1A2, CYP2B6, CYP2C9 and CYP2C19, decrease preceded by a reduction in activity. On the other hand, acute moderate hypoxia up-regulates CYP3A6. The changes in protein expression are preceded by modifications in the mRNA coding for the proteins. The effect of hypoxia on hepatic cytochrome P450 is carried out by serum mediators, e.g. interferon-gamma, interleukin-1beta, and interleukin-2 are responsible for the decrease in activity and in expression of cytochrome P450 isoforms, and erythropoietin accounts for the increase in CYP3A6. Probably several mechanisms underlie and contribute to the decrease in activity and down-regulation of cytochrome P450 isoforms by hypoxia, e.g. reducing potentiation factors, inducing repressor elements and activating negative regulatory elements. The up-regulation of CYP3A6 implies a PTK- and p42/44MAPK-dependent stabilization/activation, nuclear translocation of HIF-1 and AP-1, binding to CYP3A6 promoter, and transactivation of the gene to induce CYP3A6 expression.
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PMID:Effect of hypoxia on cytochrome P450 activity and expression. 1518 Apr 95

Hypoxia-inducible factor (HIF)-1 alpha is the regulatory subunit of HIF-1 that is stabilized under hypoxic conditions. Under different circumstances, HIF-1 alpha may promote both tumorigenesis and apoptosis. There is conflicting data on the importance of HIF-1 alpha as a prognostic factor. This study evaluated HIF-1 alpha expression in 172 consecutive patients with stage I-IIIA non small cell lung cancer (NSCLC) using standard immunohistochemical techniques. The extent of HIF-1 alpha nuclear immunostaining was determined using light microscopy and the results were analyzed using the median (5%) as a low cut-point and 60% as a high positive cut-point. Using the low cut-point, positive associations were found with epidermal growth factor receptor (EGFR; p = 0.01), matrix metalloproteinase (MMP)-9 (p = 0.003), membranous (p < 0.001) and perinuclear (p = 0.004) carbonic anhydrase (CA) IX, p53 (p = 0.008), T-stage (p = 0.042), tumor necrosis (TN; p < 0.001) and squamous histology (p < 0.001). No significant association was found with Bcl-2 or either N- or overall TMN stage or prognosis. When the high positive cut-point was used, HIF-1 alpha was associated with a poor prognosis (p = 0.034). In conclusion, the associations with EGFR, MMP-9, p53 and CA IX suggest that these factors may either regulate or be regulated by HIF-1 alpha. The association with TN and squamous-type histology, which is relatively more necrotic than other NSCLC types, reflects the role of hypoxia in the regulation of HIF-1 alpha. The prognostic data may reflect a change in the behavior of HIF-1 alpha in increasingly hypoxic environments.
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PMID:Hypoxia-inducible factor-1 alpha in non small cell lung cancer: relation to growth factor, protease and apoptosis pathways. 1518 41

We proposed a model in which myocardial hypoxia triggers the apoptosis-dependent remodeling of the avian outflow tract (OFT) in the transition of the embryo to a dual circulation. In this study, we examined hypoxia-dependent signaling in cardiomyocyte apoptosis and outflow tract remodeling. The hypoxia-inducible transcription factor HIF-1alpha was specifically present in the nuclei of OFT cardiomyocytes from stages 25-32, the period of hypoxia-dependent OFT remodeling. HIF-1alpha expression was sensitive to changes in ambient oxygen concentrations, while its dimerization partner HIF-1beta was constitutively expressed. There was not a simple relationship between HIF-1alpha expression and apoptosis. Apoptotic cardiomyocytes were detected in HIF-1alpha-positive and -negative regions, and a hypoxic stimulus sufficient to induce nuclear accumulation of HIF-1alpha did not induce cardiomyocyte apoptosis. The hypoxia-dependent expression of the vascular endothelial growth factor receptor (VEGFR2) in the distal OFT myocardium may be protective as cardiomyocyte apoptosis in the early stages (25-30) of OFT remodeling was absent from this region. Furthermore, recombinant adenoviral-mediated expression of dominant negative Akt, an inhibitor of tyrosine kinase receptor signaling, augmented cardiomyocyte apoptosis in the OFT and constitutively active Akt suppressed it. Adenovirus-mediated forced expression of VEGF165 induced conotruncal malformation such as double outlet right ventricle (DORV) and ventricular septal defect (VSD), similar to defects observed when apoptosis-dependent remodeling of the OFT was specifically targeted. We conclude that normal developmental remodeling of the embryonic avian cardiac OFT involves hypoxia/HIF-1-dependent signaling and cardiomyocyte apoptosis. Autocrine signaling through VEGF/VEGFR2 and Akt provides survival signals for the hypoxic OFT cardiomyocytes, and regulated VEGF signaling is required for the normal development of the OFT.
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PMID:Hypoxia-responsive signaling regulates the apoptosis-dependent remodeling of the embryonic avian cardiac outflow tract. 1532 13

Hypoxia-inducible factor (HIF) is critical in the modulation of tumour angiogenesis in response to hypoxia. In the present study, the mechanisms underlying basic fibroblast growth factor (bFGF)-induced activation of HIF-1 and the subsequent release of vascular endothelial growth factor (VEGF) in a human breast cancer cell line (T47D) under normoxic conditions were explored. The data show that HIF-1alpha expression is induced by bFGF in a dose- and time-dependent fashion, while increased HIF-1alpha protein expression and transactivity of HIF-1 are due to the phosphorylation of Akt by bFGF, as indicated by application of the phosphatidylinositol 3-kinase (PI-3K) inhibitor LY294002. The data also show that the MEK1 (mitogen-activated protein kinase kinase-1)/ERK (extracellular signal-regulated kinase) pathway is only involved in bFGF-induced transactivity of HIF-1, but not HIF-1alpha expression, indicating roles for both the PI-3K/Akt and the MEK1/ERK pathways in bFGF activity. In addition, the translation inhibitor cycloheximide confirmed that bFGF-induced HIF-1alpha protein expression was due to de novo protein synthesis. In contrast, p38 was not required for the expression of HIF-1alpha or HIF-1 transactivity, although significant phosphorylation of p38 was observed after bFGF treatment. Treatment of the cells with bFGF increased the amount of VEGF release, and this could be suppressed by either PD98059 or LY294002, suggesting the presence of a HIF-1alpha-dependent pathway for bFGF-induced VEGF production. In conclusion, the PI-3K/Akt and MEK1/ERK pathways, in a potentially independent and co-operative fashion, can modulate HIF-1 activation by bFGF. Further studies will pinpoint whether HIF-1 is the transcriptional factor responsible for the increased VEGF production following bFGF treatment of breast tumour cells.
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PMID:In vitro study of HIF-1 activation and VEGF release by bFGF in the T47D breast cancer cell line under normoxic conditions: involvement of PI-3K/Akt and MEK1/ERK pathways. 1571 61


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