The mechanisms that regulate angiogenesis in hypoxia or hypoxic microenvironment are modulated by several pro- and antiangiogenic factors. Hypoxia-inducible factors (HIFs) have been established as the basic and major inducers of angiogenesis, but understanding the role of interacting proteins is becoming increasingly important to elucidate the angiogenic processes of a hypoxic response. In particular, with regard to wound healing and the novel therapies for vascular disorders such as ischemic brain and heart attack, it is essential to gain insights in the formation and regulation of HIF transcriptional machineries related to angiogenesis. Further, identification of alternative ways of inhibiting tumor growth by disrupting the growth-triggering mechanisms of increasing vascular supply via angiogenesis depends on the knowledge of how tumor cells develop their own vasculature. Here, we review our findings on the interactions of basic HIFs, HIF-1alpha and HIF-2alpha, with their regulatory binding proteins, histone deacetylase 7 (HDAC7) and translation initiation factor 6 (Int6), respectively. The present results and discussion revealed new regulatory interactions of HIF-related mechanisms.
Animals ; Anoxia/genetics/*metabolism ; Gene Expression Regulation ; Histone Deacetylases/genetics/metabolism ; Humans ; Hypoxia-Inducible Factor 1/genetics/*metabolism ; Neovascularization, Pathologic/genetics/*metabolism

We report here, that a vector constructed based on ppET-1 gene promoter and 5' untranslated region induced a high level of gene expression in endothelial cells and the specificity is even further enhanced under hypoxia-mimic conditions due to a natural hypoxia responsive element within the promoter region. A naked DNA vector that confers endothelial cell specific gene expression as well as efficient levels of gene expression was constructed with an endothelial cell specific naked DNA vector, pETlong, by using the full length promoter of the preproendothelin-1 gene and the entire 5' untranslated region upstream from the start codon. Inclusion of the entire 5' untranslated region in pETlong increased gene expression 2.96 fold as compared with that from pETshort, which contains only the promoter sequences. Reporter gene expression from pETlong was 7.9 fold higher as compared with that from CMV-driven promoter based vector in calf pulmonary endothelial cells. However, in nonendothelial COS cells, luciferase activity from pETlong was only 0.3 fold as compared with that of CMV-based vector. Similar results were observed in other nonendothelial cells. These results demonstrate that the pETlong drives gene expression in endothelial cells with high efficacy and specificity. We have examined hypoxia responsiveness of pETlong as the promoter region of the preproendothelin-1 gene contains hypoxia responsive elements. The activity of the pETlong vector was increased 1.6 fold under hypoxia-mimic conditions using cobalt chloride. The high levels of hypoxia-inducible expression in endothelial cells relative to the low levels of background expression in other cells shows that pETlong could be a useful tool for vascular targeting of vascular disease and cancer gene therapy.
*5' Untranslated Regions ; Animals ; Anoxia/metabolism ; Cattle ; Endothelial Cells/*metabolism ; Endothelin-1/*genetics/metabolism ; Endothelium, Vascular/metabolism ; Gene Transfer Techniques ; *Genetic Vectors ; Human ; *Promoter Regions (Genetics)

STATs (signal transducers and activators of transcription) are proteins with dual functions: signal transducers in the cytoplasm and transcriptional activators in the nucleus. STAT proteins act as transcription factors activated by phosphorylation on its tyrosine residues upon stimulation by various cytokines. The phosphorylated STAT molecules then form homo- or heterodimers through SH2-mediated interaction and translocate into the nucleus to activate the transcription of various target genes. STAT5 recognizes the interferon-gamma activated site TTCNNNGAA (GAS sequence) in the promoter region of the beta-casein gene. Except for prolactin-dependent beta-casein production in mammary gland cells, the biological consequences of STAT5a activation in various systems are not clear. Here we showed that STAT5a was phosphorylated 10 min after desferrioxamine (DFO) treatment, and reached a maximum induction at 4 h in mammary epithelial cells (HC11) and transfected COS-7 cells. Under hypoxic conditions (2% O2), a maximal phosphorylation of STAT5a was observed within 6 h. EMSA (electrophoretic mobility shift assay) showed that DFO or hypoxia enhanced the binding activities of STAT5a DNA to beta-casein gene promoter in mammary epithelial cells (HC11) and transfected COS-7 cells. These results showed that DFO or hypoxia induces tyrosine phosphorylation of STAT5a and also increases the binding activity of STAT5a DNA in mammary epithelial cells. Our data suggest that the STAT5 may act as a mediator in hypoxia-mediated gene expression.
Animals ; Anoxia/*genetics/*metabolism ; Caseins/genetics ; Cell Line ; DNA/genetics/metabolism ; DNA-Binding Proteins/*metabolism ; Deferoxamine/pharmacology ; Epithelial Cells/drug effects/*metabolism ; Gene Expression Regulation ; Mammary Glands, Animal/cytology/*metabolism ; Mice ; Phosphorylation/drug effects ; Phosphotyrosine/metabolism ; Promoter Regions (Genetics)/genetics ; Protein Binding ; Response Elements/*genetics ; Support, Non-U.S. Gov't ; Trans-Activators/*metabolism

PURPOSE: Although follicular thyroid cancer (FTC) has a relatively fair prognosis, distant metastasis sometimes results in poor prognosis and survival. There is little understanding of the mechanisms contributing to the aggressiveness potential of thyroid cancer. We showed that hypoxia inducible factor-1alpha (HIF-1alpha) induced aggressiveness in FTC cells and identified the underlying mechanism of the HIF-1alpha-induced invasive characteristics. MATERIALS AND METHODS: Cells were cultured under controlled hypoxic environments (1% O2) or normoxic conditions. The effect of hypoxia on HIF-1alpha, and epithelial-to-mesenchymal transition (EMT) related markers were evaluated by quantitative real-time PCR, Western blot analysis and immunocytochemistry. Invasion and wound healing assay were conducted to identify functional character of EMT. The involvement of HIF-1alpha and Twist in EMT were studied using gene overexpression or silencing. After orthotopic nude mouse model was established using the cells transfected with lentiviral shHIF-1alpha, tissue analysis was done. RESULTS: Hypoxia induces HIF-1alpha expression and EMT, including typical morphologic changes, cadherin shift, and increased vimentin expression. We showed that overexpression of HIF-1alpha via transfection resulted in the aforementioned changes without hypoxia, and repression of HIF-1alpha with RNA interference suppressed hypoxia-induced HIF-1alpha and EMT. Furthermore, we also observed that Twist expression was regulated by HIF-1alpha. These were confirmed in the orthotopic FTC model. CONCLUSION: Hypoxia induced HIF-1alpha, which in turn induced EMT, resulting in the increased capacity for invasion and migration of cells via regulation of the Twist signal pathway in FTC cells. These findings provide insight into a possible therapeutic strategy to prevent invasive and metastatic FTC.
Adenocarcinoma, Follicular/*genetics/metabolism ; Animals ; Anoxia/*genetics ; Cadherins/genetics ; Epithelial-Mesenchymal Transition/*genetics ; Gene Expression Regulation, Neoplastic ; Hypoxia-Inducible Factor 1, alpha Subunit/*genetics/metabolism ; Lymphokines ; Mice ; Neoplasm Invasiveness ; Phenotype ; Real-Time Polymerase Chain Reaction ; Signal Transduction/drug effects ; Thyroid Neoplasms/*genetics/metabolism ; Transcriptional Activation ; Twist Transcription Factor/*genetics/metabolism ; Vimentin/metabolism

PURPOSE: The nasal mucosa is the first site to encounter pathogens, and it forms continuous barriers to various stimuli. This barrier function is very important in the innate defense mechanism. Additionally, inflammation of the nasal sinus is known to be a hypoxic condition. Here, we studied the effect of hypoxia on barrier function in normal human nasal epithelial (NHNE) cells. MATERIALS AND METHODS: The expression levels of various junction complex proteins were assessed in hypoxia-stimulated NHNE cells and human nasal mucosal tissues. We performed real-time polymerase chain reaction analysis, western blotting, and immunofluorescence assays to examine differences in the mRNA and protein expression of ZO-1, a tight junction protein, and E-cadherin in NHNE cells. Moreover, we evaluated the trans-epithelial resistance (TER) of NHNE cells under hypoxic conditions to check for changes in permeability. The expression of ZO-1 and E-cadherin was measured in human nasal mucosa samples by western blotting. RESULTS: Hypoxia time-dependently decreased the expression of ZO-1 and E-cadherin at the gene and protein levels. In addition, hypoxia decreased the TER of NHNE cells, which indicates increased permeability. Human nasal mucosa samples, which are supposed to be hypoxic, showed significantly decreased levels of ZO-1 and E-cadherin expression compared with control. CONCLUSION: Our results demonstrate that hypoxia altered the expression of junction complex molecules and increased epithelial permeability in human nasal epithelia. This suggests that hypoxia causes barrier dysfunction. Furthermore, it may be associated with innate immune dysfunction after encountering pathogens.
Anoxia/etiology/*metabolism ; Blotting, Western ; Cadherins/*analysis/genetics ; Epithelium/chemistry/pathology ; Humans ; Membrane Proteins/*analysis ; Nasal Mucosa/*chemistry/pathology/*secretion ; Permeability/*radiation effects ; RNA, Messenger/genetics/metabolism ; Real-Time Polymerase Chain Reaction ; Tight Junctions/*metabolism ; Zonula Occludens-1 Protein

Oxidative stress is critical for causing cardiac injuries during ischemia-reperfusion (IR), yet the molecular mechanism for this remains unclear. In the present study, we observe that hypoxia and reoxygenation, a component of ischemia, effectively induces apoptosis in the cardiac myocytes from neonatal rats and it concomitantly leads to induction of GADD153, an apoptosis-related gene. Furthermore, IR injury of rat heart showed a GADD153 overexpression in the ischemic area where the TUNEL reaction was positive. A downregulation of cardiac ankyrin repeat protein (CARP) was also observed in this ischemic area. Promoter deletion and reporter analysis revealed that hypoxia transcriptionally activates a GADD153 promoter through the AP-1 element in neonatal cardiomyocytes. Ectopic overexpression of GADD153 resulted in the downregulation of CARP expression. Accordingly, the induction of GADD153 mRNA were followed by the CARP down-regulation in an in vivo rat coronary ischemia/reperfusion injury model. These results suggest that GADD153 over-expression and the resulting downregulation of CARP may have causative roles in apoptotic cell death during cardiac IR injury.
Animals ; Animals, Newborn ; Anoxia ; Apoptosis/physiology ; Cells, Cultured ; Humans ; Male ; *Myocardial Reperfusion Injury/metabolism/pathology ; *Myocardium/metabolism/pathology ; Myocytes, Cardiac/cytology/metabolism ; Nuclear Proteins/genetics/*metabolism ; Promoter Regions, Genetic ; Rats ; Rats, Sprague-Dawley ; Repressor Proteins/genetics/*metabolism ; Transcription Factor AP-1/genetics/metabolism ; Transcription Factor CHOP/genetics/*metabolism

In order to study the effect of nitric oxide (NO) on the expression of hypoxia-inducible factor-1 alpha (HIF-1alpha) mRNA in hypoxic pulmonary hypertension (HPH) rats, 30 healthy male Wistar rats were randomly divided into normoxic control group, chronic hypoxic group and hypoxia plus L-arginine (L-Arg) group. The animal model of HPH was developed. The mean pulmonary arterial pressure (mPAP) was measured by inserting a microcatheter into the pulmonary artery. The HIF-1alpha mRNA expression levels were detected by in situ hybridization (ISH) and semiquantitative RT-PCR. It was found that after 14 days hypoxia, the mPAP in normoxic control group (17.6 +/- 2.7 mmHg, 1 mmHg=0.133 kPa) was significantly lower than that in chronic hypoxic group (35.8 +/- 6.1 mmHg, t=0.2918, P<0.05) and mPAP in chronic hypoxic group was higher than that in hypoxia plus L-arginine group (24.4 +/- 3.8 mmHg, t=0.2563, P<0.05). ISH showed that the expression of HIF-1alpha mRNA in the intraacinar pulmonary arteriolae (IAPA) in normoxic control group (0.1076 +/- 0.0205) was markedly weaker than that in chronic hypoxic group (0.3317 +/- 0.0683, t=3.125, P<0.05) and that in chronic hypoxic group was stronger than that in hypoxia plus L-arginine group (0.1928 +/- 0.0381, t=2.844, P<0.05). RT-PCR showed that the content of HIF-1alpha mRNA in chronic hypoxic group (2.5395 +/- 0.6449) was 2.16 times and 1.75 times higher than that in normoxic control group (1.1781 +/- 0.3628) and hypoxia plus L-arginine group (1.4511 +/- 0.3981), respectively. It is concluded that NO can reduce the mPAP by the inhibition of the expression of HIF-1alpha mRNA, which may be one of the mechanisms through which NO affects the pathogenesis of HPH.
Anoxia/metabolism ; Arginine/pharmacology ; Hypertension, Pulmonary/*metabolism ; Hypoxia-Inducible Factor 1, alpha Subunit ; Nitric Oxide/*pharmacology ; RNA, Messenger/biosynthesis ; RNA, Messenger/genetics ; Random Allocation ; Rats, Wistar ; Reverse Transcriptase Polymerase Chain Reaction ; Transcription Factors/*biosynthesis ; Transcription Factors/genetics

BACKGROUND/AIMS: Renal hypoxia is involved in the pathogenesis of diabetic nephropathy. Pentoxifyllin (PTX), a nonselective phosphodiesterase inhibitor, is used to attenuate peripheral vascular diseases. To determine whether PTX can improve renal hypoxia, we investigated its effect in the streptozocin (STZ)-induced diabetic kidney. METHODS: PTX (40 mg/kg, PO) was administered to STZ-induced diabetic rats for 8 weeks. To determine tissue hypoxia, we examined hypoxic inducible factor-1alpha (HIF-1alpha), heme oxygenase-1 (HO-1), vascular endothelial growth factor (VEGF), and glucose transporter-1 (GLUT-1) levels. We also tested the effect of PTX on HIF-1alpha in renal tubule cells. RESULTS: PTX reduced the increased protein creatinine ratio in diabetic rats at 8 weeks. HIF-1alpha, VEGF, and GLUT-1 mRNA expression increased significantly, and the expression of HO-1 also tended to increase in diabetic rats. PTX significantly decreased mRNA expression of HIF-1alpha and VEGF at 4 and 8 weeks, and decreased HO-1 and GLUT-1 at 4 weeks. The expression of HIF-1alpha protein was significantly increased at 4 and 8 weeks in tubules in the diabetic rat kidney. PTX tended to decrease HIF-1alpha protein expression at 8 weeks. To examine whether PTX had a direct effect on renal tubules, normal rat kidney cells were stimulated with CoCl2 (100 microM), which enhanced HIF-1alpha mRNA and protein levels under low glucose conditions (5.5 mM). Their expressions were similar even after high glucose (30 mM) treatment. PTX had no effect on HIF-1alpha expression. CONCLUSIONS: PTX attenuates tubular hypoxia in the diabetic kidney.
Animals ; Anoxia/*drug therapy/enzymology/etiology/genetics ; Cell Line ; Cobalt/pharmacology ; Diabetes Mellitus, Experimental/*complications ; Diabetic Nephropathies/*drug therapy/enzymology/etiology/genetics ; Disease Models, Animal ; Gene Expression Regulation/drug effects ; Glucose/metabolism ; Glucose Transporter Type 1/genetics ; Heme Oxygenase (Decyclizing)/genetics/metabolism ; Hypoxia-Inducible Factor 1, alpha Subunit/genetics/metabolism ; Kidney Tubules/*drug effects/enzymology ; Male ; Pentoxifylline/*pharmacology ; Phosphodiesterase Inhibitors/*pharmacology ; RNA, Messenger/metabolism ; Rats ; Rats, Sprague-Dawley ; Streptozocin ; Time Factors ; Vascular Endothelial Growth Factor A/genetics

We investigated the expression of heme oxygenase-1 (HO-1) gene and production of endogenous carbon monoxide (CO) in the rat lung tissue at different time points of chronic hypoxic pulmonary hypertension and the effect of hemin on the expression of HO-1 gene and pulmonary hypertension. A rat model of hypoxic pulmonary hypertension was recreated by exposure to intermittent normobaric hypoxic environment (10% O2). Reverse transcriptase polymerase chain reaction (RT-PCR) was performed to determine the level of HO-1 mRNA in the rat lung tissue and double wave length spectrophotometry was used to evaluate the quantity of COHb in arterial blood. Cardiac catheterization was employed to measure the right ventricular systolic pressure (RVSP) and HE staining was performed in dissected lung tissue to observe the pathological changes of the intra-acinar pulmonary arteries (IAPA). It was found that (1) There was a low level of HO-1 mRNA in normal rat lung tissue, but the level of HO-1 mRNA increased by 2-4 times in the lung tissue of hypoxic rats (P<0.01). The quantity of COHb was 2-3 times those of control group (P<0.01 or P<0.05). These were accompanied by the increased of RVSP and the thickened IAPA; (2) Hemin could keep the HO-1 mRNA and COHb in the hypoxic rat lung tissue at a high level, and partially suppressed the increase of rat RVSP, thereby ameliorating the pathological changes of IAPA. In conclusion, the upregulation of the expression of HO-1 gene and production of CO in the rat lung of hypoxic pulmonary hypertension plays a role of inhibition in the development of hypoxic pulmonary hypertension. Hemin has a therapeutic effect on hypoxic pulmonary hypertension.
Anoxia/complications ; Carbon Monoxide/*metabolism ; Carbon Monoxide/physiology ; Heme Oxygenase (Decyclizing)/*biosynthesis ; Heme Oxygenase (Decyclizing)/genetics ; Heme Oxygenase-1 ; Hypertension, Pulmonary/etiology ; Hypertension, Pulmonary/*metabolism ; Lung/metabolism ; Myocytes, Smooth Muscle/drug effects ; Myocytes, Smooth Muscle/pathology ; Pulmonary Artery/metabolism ; Pulmonary Artery/*pathology ; RNA, Messenger/biosynthesis ; RNA, Messenger/genetics

Clinical studies have shown that tumor hypoxia is associated with invasive growth and metastasis and may be an important prognostic factor adversely influencing survival in patients with tumors. To investigate the mechanisms involved in hypoxia-induced invasive growth and metastasis, hypoxia-mediated urokinase plasmalogen activator receptor (uPAR) expression, cellular invasiveness, and mitogen activated protein kinase (MAPK) activation were measured in a prostate cancer cell line, PC3MLN4. The levels of uPAR expression and cellular invasiveness were increased in hypoxic cells. Hypoxia-induced cellular invasiveness was blocked by an anti-uPAR monoclonal antibody. Phosphorylations of ERK and p38 kinases were also more extensive in hypoxic cells than in normoxic cells. Hypoxia-induced uPAR up-regulation was inhibited by pre-treatments with a specific inhibitor of MEK, PD98059 and a specific inhibitor of p38 MAP kinase, SB203580. Cell growth also increased in hypoxic cells. From these results, hypoxia increased tumor cell invasion by up-regulating uPAR expression, which might be mediated through ERK and p38 kinase signaling pathways in PC3MLN4 prostate cancer cell line.
Animals ; Anoxia/*metabolism ; Cell Line, Tumor ; Cell Proliferation ; Humans ; MAP Kinase Signaling System/*physiology ; Male ; Mitogen-Activated Protein Kinases/*metabolism ; Phosphorylation ; Prostatic Neoplasms/*metabolism/pathology ; Protein Kinase Inhibitors/metabolism ; Receptors, Cell Surface/genetics/*metabolism ; Research Support, Non-U.S. Gov't ; *Up-Regulation