Effects Of Hypoxia-inducible Factor-1α Research Articles

Hypoxia-inducible factor-1α attenuates renal podocyte injury in male rats in a simulated high-altitude environment by upregulating Krüppel-like factor 4 expression.

Previous studies have shown that podocyte injury is involved in the development of proteinuria in rats under hypobaric hypoxia conditions. Prolyl hydroxylase inhibitors (PHIs) may reduce proteinuria. This study aimed to further investigate whether the protective effects of hypoxia-inducible factor 1α (HIF1α) on podocyte injury induced by hypobaric hypoxia are related to Krüppel-like factor 4 (KLF4). Rats were housed in a low-pressure oxygen chamber to simulate a high-altitude environment (5000m), and a PHI was intraperitoneally injected. Urinary protein electrophoresis was performed and the morphology of the podocytes was observed by electron microscopy. Rat podocytes were cultured under 1% O2, and siRNA was used to interfere with KLF4 expression. The protein expression levels of HIF1α, KLF4, CD2-associated protein (CD2AP) and nephrin were determined by western blotting. Compared with those in the experimental group, the rats in the intervention group on day 14 had lower urinary protein levels, increased protein expression levels of CD2AP and nephrin, and reduced podocyte injury. The results of in vitro experiments showed that the protein expression levels of KLF4, CD2AP and nephrin were greater in the PHI intervention group and lower in the HIF1α inhibitors group than in the low-oxygen group. The protein expression of CD2AP and nephrin in the siKLF4-transfected podocytes treated with PHI and HIF1α inhibitors did not differ significantly from that in the low-oxygen group. HIF1α may be involved in reducing progressive high-altitude proteinuria by regulating KLF4 expression and contributing to the repair of podocyte injury induced by hypobaric hypoxia.

PM2.5 induce the defective efferocytosis and promote atherosclerosis via HIF-1α activation in macrophage

Epidemiological studies demonstrate that fine particulate matter (PM2.5) promotes the development of atherosclerosis. However, the mechanism insight of PM2.5-induced atherosclerosis is still lacking. The aim of this study was to explore the biological effects of hypoxia-inducible factor 1α (HIF-1α) on PM2.5-triggered atherosclerosis. The vascular stiffness, carotid intima-media thickness (CIMT), lipid and atherosclerotic lesion were increased when von Hippel-Lindau (VHL)-null mice were exposed to PM2.5. Yet, knockout of HIF-1α markedly decreased the PM2.5-triggered atherosclerotic lesion. We firstly performed microarray analysis in PM2.5-treated bone morrow-derived macrophages (BMDMs), which showed that PM2.5 significantly changed the genes expression patterns and affected biological processes such as phagocytosis, apoptotic cell clearance, cellular response to hypoxia, apoptotic process and inflammatory response. Moreover, the data showed knockout of HIF-1α remarkably relieved PM2.5-induced defective efferocytosis. Mechanistically, PM2.5 inhibited the level of genes and proteins of efferocytosis receptor c-Mer tyrosine kinase (MerTK), especially in VHL-null BMDMs. In addition, PM2.5 increased the genes and proteins of a disintegrin and metallopeptidase domain 17 (ADAM17), which caused the MerTK cleavage to form soluble MerTK (sMer) in plasma and cellular supernatant. The sMer was significantly up-regulated in plasma of VHL-null PM2.5-exposed mice. Moreover, PM2.5 could induce defective efferocytosis and activate inflammatory response through MerTK/IFNAR1/STAT1 signaling pathway in macrophages. Our results demonstrate that PM2.5 could induce defective efferocytosis and inflammation by activating HIF-1α in macrophages, ultimately resulting in accelerating atherosclerotic lesion formation and development. Our data suggest HIF-1α in macrophages might be a potential target for PM2.5-related atherosclerosis.

Effects of hypoxia inducible factor-1α on osteogenic differentiation and angiogenesis related factors of bone marrow mesenchymal stem cells

Effects of hypoxia inducible factor-1α on osteogenic differentiation and angiogenesis related factors of bone marrow mesenchymal stem cells

Amelioration of chronic kidney disease-associated anemia by vadadustat in mice is not dependent on erythroferrone

Vadadustat is an investigational hypoxia-inducible factor prolyl hydroxylase inhibitor that increases endogenous erythropoietin production and has been shown to decrease hepcidin levels, ameliorate iron restriction, and increase hemoglobin concentrations in anemic patients with chronic kidney disease (CKD). In studies of physiological responses to other erythropoietic stimuli, erythropoietin induced erythroblast secretion of erythroferrone (ERFE), which acts on the liver to suppress hepcidin production and mobilize iron for erythropoiesis. We therefore investigated whether vadadustat effects on erythropoiesis and iron metabolism are dependent on ERFE. Wild type and ERFE knockout mice with and without CKD were treated with vadadustat or vehicle. In both wild type and ERFE knockout CKD models, vadadustat was similarly effective, as evidenced by normalized hemoglobin concentrations, increased expression of duodenal iron transporters, lower serum hepcidin levels, and decreased tissue iron concentrations. This is consistent with ERFE-independent increased iron mobilization. Vadadustat treatment also lowered serum urea nitrogen and creatinine concentrations and decreased expression of kidney fibrosis markers. Lastly, vadadustat affected fibroblast growth factor 23 (FGF23) profiles: in non-CKD mice, vadadustat increased plasma total FGF23 out of proportion to intact FGF23, consistent with the known effects of hypoxia-inducible factor-1α and erythropoietin on FGF23 production and metabolism. However, in the mice with CKD, vadadustat markedly decreased both total and intact FGF23, effects likely contributed to by the reduced loss of kidney function. Thus, in this CKD model, vadadustat ameliorated anemia independently of ERFE, improved kidney parameters, and decreased FGF23. How vadadustat affects CKD progression in humans warrants future studies.

Effects of hypoxia inducible factor-1α on expression levels of MLCK, p-MLC and ZO-1 of rat endothelial cells

ObjectiveTo examine the aberrant expression of endothelial permeability associated proteins including MLCK, p-MLC and ZO-1 in presence of different levels of hypoxia-inducible factor 1 alpha (HIF-1α). MethodsWe established monolayer vascular endothelial cell model with the primary rat endothelial cells. Over-expressed or under-expressed HIF-1α cell lines were made by endothelial cells transfected with plasmid vector constructed with HIF-1α gene or HIF-1α-specific short hairpin RNA (shRNA). Levels of mRNA and protein of MLCK, p-MLC and ZO-1 were determined using Real-Time PCR and Western blot. All data were analyzed using by One-Way ANOVA method and LSD. ResultsWe successfully cultured the rat endothelial primary cells for four days. The mRNA and protein levels of MLCK and p-MLC were significantly increased in the HIF-1α over-expression group than that in the blank control group and the empty plasmid GV230 group (P＜0.05). ZO-1 was significantly lower in the HIF-1α over-expression group than that in the blank control group and the GV230 group. On the contrary, the mRNA and protein levels of MLCK and p-MLC were significantly lower in the HIF-1α under-expression group than that in the blank control group and the shRNA-NC group (P＜0.05). ZO-1 was significantly higher in the HIF-1α low-expression group than that in the blank control group and the shRNA-NC group. ConclusionHIF-1α positively regulates the expression of MLCK and p-MLC and negatively regulates the expression of ZO-1 in rat monolayer endothelial cells.

Effects of hypoxia-inducible factor 1α on hypoxic tolerance of human amniotic mesenchymal stem cells

Under hypoxic conditions, the survival and apoptosis of human amniotic mesenchymal stem cells (hAMSCs) were observed by transient transfection of hypoxia-inducible factor 1α (HIF-1α) gene, to investigate the effect of HIF-1α on hypoxic tolerance of hAMSCs. The hAMSCs were isolated and cultured from amniotic membrane tissue from voluntary donors who were treated with cesarean section. And the morphological observation by inverted phase contrast microscope and immunofluorescence detection of the expressions of stem cell markers OCT-4 and NANOG were performed to identify the cultured cells. The third generation hAMSCs were treated with 200 μmol/L CoCl 2, and transient transfection of plasmids were added according to the following grouping: group A was hAMSCs blank group; group B was pcDNA3.1 negative control group; group C was short hairpin RNA (shRNA) negative control group; group D was shRNA-HIF-1α interference group; group E was pcDNA3.1-HIF-1α over expression group. Cell survival rate of each group was measured by cell counting kit 8 (CCK-8) at 12, 24, 48 hours after hypoxia treatment. Flow cytometry was used to detect apoptosis rate of each group at 24 hours after hypoxia treatment. The expression levels of HIF-1α, vascular endothelial growth factor (VEGF), B-cell lymphoma 2 (Bcl-2), Bax, and cleaved Caspase-3 (C-Caspase-3) proteins were detected by Western blot at 24 hours after hypoxia treatment. CCK-8 assay showed that the cell survival rate of group D was significantly lower than those of groups A and C at all time points after hypoxia treatment; while the cell survival rate in group E was significantly increased than those in groups A and B, and the diffrences at 24 hours were significant ( P<0.05). In group E, the cell survival rate at 24 hours was significantly higher than those at 12 and 48 hours ( P<0.05). The results of flow cytometry showed that the apoptosis rate in group D was significantly higher than those in groups A and C ( P<0.05), and the apoptosis rate in group E was significantly lower than those in groups A and B ( P<0.05). Western blot showed that the expressions of HIF-1α, VEGF, and Bcl-2 proteins in group D were significantly decreased when compared with those in groups A and C, and the expressions of Bax and C-Caspase-3 proteins were significantly increased ( P<0.05). On the contrary, the expressions of HIF-1α, VEGF, and Bcl-2 proteins in group E were significantly higher than those in groups A and B, and the expressions of Bax and C-Caspase-3 proteins were significantly decreased ( P<0.05). Overexpression of HIF-1α gene can significantly improve hAMSCs tolerance to hypoxia, the mechanism may be related to up-regulation of VEGF and Bcl-2 expressions, and down-regulation of Bax and C-Caspase-3 expressions.

Effects of Triple-Mutated Hypoxia-Inducible Factor-1α on Angiogenesis and Cardiac Function Improvement in Rats with Myocardial Infarction

Background/Aims: The effects of hypoxia-inducible factor-1α (HIF-1α) on angiogenesis and cardiac function improvement in rats with myocardial infarction (MI) is unknown and our current study was to evaluate whether HIF-1α would be beneficial for angiogenesis and cardiac function improvement in MI rats. Methods: A mutant of adenovirus HIF-1α (Ad-HIF-1α-Trip) was constructed by three sites mutation (Pro402, Pro564 and Asn803) in HIF-1α. The rat MI model was produced by permanent ligation of left anterior descending artery and 1×10⁹ PFU adenovirus (Ad) vector particles of Ad-Null, Ad- HIF-1a-564/402, Ad- HIF-1a-Trip, 250ng vascular endothelial growth factor (VEGF) in 0.5ml saline or only 0.5 ml saline were injected intramuscularly around the infarct border zone. Real-time PCR, ELISA and western blotting were used to evaluate angiogenesis factors expression. Capillary density and necrotic areas were detected by immunohistochemistry staining and TTC staining, respectively. Cardiac function assessment was done by echocardiography before operation and on day 7, 14 and 28 after MI. Blood samples were drawn for the measurement of cardiac biomarkers, liver function and kidney function. Results: On day 7, compared to the other groups, the expressions of HIF-1α and angiogenesis factors, and the capillary density were all significantly higher in the Ad-HIF-1α-Trip group. However, on day 28, no significant between-group differences were observed. After 72 hours of MI, serum level of cardiac biomarkers and the necrotic areas were significantly lower in the Ad-HIF-1a-Trip group compared to the other groups. Echocardiography showed that on day 7, cardiac functions were significantly reduced in all groups compared to the baseline. Cardiac function in the Ad-HIF-1α-Trip group was decreased less profoundly through day 7 to day 28 compared to the other groups. Importantly, no significant differences in liver and renal function were observed. Conclusion: Mutation of Pro402, Pro564 and Asn803 are beneficial for enhancement of the efficacy of HIF-1α. Ad-HIF–1α-Trip is able to improve angiogenesis and cardiac function, which may be a promising avenue for treatment of ischemic heart disease in the future.

HIF-1α-l-PGDS-PPARγ regulates hypoxia-induced ANP secretion in beating rat atria

Lipocalin-type prostaglandin D synthase (L-PGDS) and peroxisome proliferator activated receptor γ (PPARγ) play important roles in cardiovascular diseases. Nevertheless, effects of hypoxia-inducible factor 1α (HIF-1α) on L-PGDS and PPARγ protein levels and its role in hypoxia-induced atrial natriuretic peptide (ANP) secretion are unclear. In perfused beating rat atria, we observed that hypoxia significantly increased HIF-1α protein levels and stimulated ANP secretion, while upregulating L-PGDS. Hypoxia-induced ANP secretion was clearly attenuated by HIF-1α antagonist 2-methoxyestradiol, downregulating both HIF-1α and L-PGDS protein levels. It was also attenuated by L-PGDS antagonists, AT-56 and HQL-49, downregulating L-PGDS protein levels. In addition, hypoxia-induced ANP secretion was accompanied by increased PPARγ protein levels and was strongly attenuated by PPARγ antagonist GW9662. Hypoxia-induced increase in atrial PPARγ protein levels were dramatically inhibited by both 2-methoxyestradiol and AT-56. These results indicated that hypoxia promotes ANP secretion, at least in part, by activating HIF-1α-l-PGDS-PPARγ signaling in beating rat atria.

Effects of hypoxia inducible factor-1α on P311 and its influence on the migration of murine epidermal stem cells

Effects of hypoxia inducible factor-1α on P311 and its influence on the migration of murine epidermal stem cells

Effects of hypoxia-inducible factor-1α on the expression of heat shock proteins 90, Caspase 3 and Caspase 9 after cerebral ischemia-reperfusion

Hypoxia-inducible factor-1α (HIF-1α)is a transcription factor that acts as a master regulator of gene expression induced by low oxygen conditions. HIF-1α is the most sensitive indicator of hypoxia and can be activated by systemic hypoxia, cerebral hemisphere ischemia and cerebral focal ischemia. HIF-1 expression can be induced by hypoxic-ischemic damage after cerebral infarction and exert its effects on hypoxia-inducible downstream genes, thus protecting hypoxic tissues and cells under hypoxic conditions via regulating the expression of its downstream target genes. This article reviews the expression of HIF-1α and its downstream target genes in acute cerebral ischemia, in order to provide a theoretical basis for gene therapy. Key words: Hypoxia inducible factor 1, αsubunit; Cerebral ischemia; Reperfusion injury; Heat-shock proteins Hsp 90

Enhancement of Drug Sensitivity by Knockdown of HIF-1α in Gastric Carcinoma Cells.

In this study, the effects of hypoxia-inducible factor-1α (HIF-1α) on gastric carcinoma (GC) drug resistance through apoptosis-related genes are investigated. First, HIF-1α-specific siRNA was synthetized and transfected into drug-resistant GC cell line OCUM-2MD3/L-OHP. Then MTT assay was applied to test the inhibition rate of GC cells by 5-fluorouracil (5-FU) and oxaliplatin (L-OHP). After that, flow cytometry (FCM) was applied to measure apoptosis rate. qPCR and Western blot assay were employed to detect HIF-1α and apoptosis-related genes. Results showed that HIF-1α in OCUM-2MD3/L-OHP cells was higher than that in OCUM-2MD3 and gastric epithelial cells. After HIF-1α-siRNA transfection, inhibition rates of 5-FU and L-OHP to tumor cells increased significantly. FCM results showed that apoptosis rate of OCUM-2MD3/L-OHP cells increased significantly. After HIF-1α-siRNA transfection, survivin and Bcl-2 decreased, whereas Bax, caspase 3, and caspase 8 increased significantly. Results from this study seem to confirm that HIF-1α getting involved in GC drug resistance is possibly due to its regulation of some apoptosis-related genes. HIF-1α may be a potential target to reverse drug resistance of GC.

Effects of hypoxia inducible factor-1α on apoptotic inhibition and glucocorticoid receptor downregulation by dexamethasone in AtT-20 cells.

BackgroundHypoxia inducible factor-1α (HIF-1α) is the central transcriptional regulator of hypoxic responses during the progression of pituitary adenomas. Although previous immunohistochemical studies revealed that HIF-1α is expressed in adreno-cortico-tropic-hormone (ACTH) pituitary adenomas, the role of HIF-1α remains unclear.MethodsAtT-20 cells were incubated under hypoxic conditions (1 % O2) for 12 h. HIF-1α mRNA and protein expression levels were measured by real-time PCR and western blotting, respectively. BrdU was used to determine the effects of hypoxia on cell viability. AtT-20 cells were transfected with siRNA targeting HIF-1α, followed by hypoxia (1 % O2) for 12 h. Apoptosis was determined by annexin V-FITC flow cytometry and Tdt-mediated dUTP nick end-labelling (TUNEL) assay. In addition, we examined interactions between HIF-1α, glucocorticoid receptor (GR), and dexamethasone under both normoxic and hypoxic conditions.ResultsHypoxia triggered the time-dependent proliferation of AtT-20 cells in association with increased HIF-1α mRNA and protein levels. However, the viability of AtT-20 cells decreased greatly when they were first transfected with HIF-1α-siRNA and then exposed to hypoxia. According to flow cytometry (annexin V-FITC and PI staining) and TUNEL analyses, a greater percentage of cells were apoptotic when transfected with HIF-1α siRNA and subsequently cultured under hypoxic conditions compared to those in the normoxia and mock groups. After AtT-20 cells were cultured in 1 % O2 and then treated with dexamethasone, HIF-1α levels significantly increased or decreased in normoxic or hypoxic conditions, respectively. Dexamethasone suppressed GR expression to a higher degree in hypoxic than normoxic conditions. Downregulation of GR by dexamethasone was greatly prevented in cells that were transfected with HIF-1α siRNA.ConclusionsThese findings strongly suggest that HIF-1α exerts an antiapoptotic role and participates in the downregulation of GR by dexamethasone in hypoxic AtT-20 cells.

Hypoxia-inducible factor-1α expression in the different stages of rat thromboangiitis obliterans.

We investigated the expression and effects of hypoxia-inducible factor-1α (HIF-1α) in rat thromboangiitis obliterans (TO). Rats were divided into sham and model groups. The model group was further divided into groups based on observation duration. Lauric acid was injected below an artery clamp to simulate TO in the model group; saline was used in the sham group. Clamps were removed 15 min after injection in both groups, and physiological changes were observed at different times (gross observation and hematoxylin and eosin staining). The animals were killed at various times following the operation and serum and muscle tissues were sampled. For the sham group: the endometrium was relatively intact; medial membrane and epineurium lesions were absent; and blood vessels and surrounding tissues had no inflammatory cell infiltration. For the model group: all subgroups displayed inflammation; large numbers of inflammatory cells were gathered; muscle tissue lost its normal texture and structure; and the internal elastic membrane was integrated. Compared with the preoperative status, HIF-1α expression increased significantly in all subgroups (P < 0.05); there was no change in the sham group. HIF-1α expression in each subgroup was different (F = 14.267, P < 0.05). Femoral artery injection of lauric acid can be used as a rat TO model owing to its simple application and success rate. HIF-1α expression increased in the early stage of TO and gradually decreased with the extension of ischemia time; it may play a leading role in TO development and can be used for diagnosis and cure evaluation.

Effects of hypoxia-inducible factor-1α and matrix metalloproteinase-9 on alveolar-capillary barrier disruption and lung edema in rat models of severe acute pancreatitis-associated lung injury

The aim of this study was to investigate the effects of hypoxia-inducible factor-1α (HIF-1α) and matrix metalloproteinase-9 (MMP-9) on alveolar-capillary barrier disruption and lung edema in rat models of severe acute pancreatitis-associated lung injury (PALI). A total of 40 male Sprague-Dawley rats were randomly divided into a sham surgery group (n=10) and three PALI groups, in which acute pancreatitis was induced by the retrograde infusion of 5% sodium taurocholate (1 ml/kg). The PALI groups were as follows: i) Untreated PALI group (n=10); ii) 2-methoxyestradiol (2ME2) group (5 mg/kg body mass; n=10); and iii) 2ME2 group (15 mg/kg body mass; n=10). In the two 2ME2 groups, the HIF-1α inhibitor 2ME2 was administered intraperitoneally 1 h after the induction of AP. The severity of the pancreatitis was evaluated by the serum amylase levels and pathology. The severity of the lung injury was evaluated by the wet/dry ratio, blood gas analysis and pathology. The alveolar-capillary barrier disruption was assessed by Evans blue dye extravasation. The protein and mRNA expression levels of HIF-1α and MMP-9 were studied using enzyme-linked immunosorbent assays (ELISAs), western blot analysis and reverse transcription-polymerase chain reaction. The active tumor necrosis factor-α levels were measured using an ELISA. The HIF-1α inhibitor 2ME2 attenuated the severity of the pancreatitis and PALI, while the lung edema and alveolar-capillary barrier disruption were significantly ameliorated compared with those in the untreated PALI group. Administration of the higher dose of 2ME2 significantly suppressed the protein expression of MMP-9 in the lung tissues. The results indicate that HIF-1α has a major function in alveolar-capillary barrier disruption and lung edema in PALI via a molecular pathway cascade involving MMP-9. Inhibition of HIF-1α by 2ME2 attenuates alveolar-capillary barrier disruption and lung edema. Pharmacological blockade of this pathway in patients with PALI may provide a novel therapeutic strategy.

Hypoxia-inducible factor 1α regulates the expression of CD18 and ninjurin-1

Objective To investigate the effects of hypoxia-inducible factor 1α (HIF-1α) small interfere RNA construct pSUPERH1-siHIF1α on the expression of CD18 and ninjurin 1 by K562 (human chronic myelogenous leukemia cell line) cells cultured with serums from patients with early stage of diabetic retinopathy.Methods K562 cells were cultured in 4 groups as control group (group A),diabetic group (group B),diabetes and pSUPERH1-siHIF1α transfect group (group C) and diabetes and pSUPER-retro transfect group (group D).The cells in group A were cultured in human serum from age-matched healthy control,and in group B,C and D,the cells were cultured in serum from the subjects of early stage of diabetic retinopathy.Twenty-four hours before the cells were cultured by the serum from the subjects of early stage of diabetic retinopathy,the HIF-1α specific siRNA expression vector pSUPERH1-siHIF1α and empty vector pSUPER-retro were transfected into the cells of group C and D,respectively.The percentages of CD18 and ninjurin-1 positive cell on the surface of K562 cells were measured by Flow Cytometry.The adherent rate between K562 and RF/6A was measured by the rose Bengal staining test.Results The percentages of CD18 positive cell in the group A,B,C and D were significantly different (F=14.33,P=0.01).The percentage of group B was significantly higher than that in group A (P=0.001) ; the percentage of group C was significantly lower than that in group B (P=0.001) and group D (P=0.02) ; the difference between group C and A was not significant (95％CI=-14.89-2.13,P=0.12).The differences of the percentage of ninjurin-1 positive cell among the group A,B,C and D were significant (F=39.38,P=0.001).The percentage of group B was significantly higher than that in group A (P=0.00); the difference of the percentage between group C and B was not significant (P =0.06),that was also not significant between group C and D (P=0.49).The differences of the adherent rate between K562 and RF/6A (rhesus monkey retinal choroid blood vessel endothelial cell line) among the group A,B,C and D were significant (F=20.62,P=0.00).The adherent rate of group B was significantly higher than that in group A (P=0.00),the adherent rate in group C was significantly lower than that in group B (P=0.01),but it was still significantly higher than that in group A (P=0.002),the difference of adherent rate between group B and D was not significant (P=0.68).Conclusion Under the early stage of diabetic retinopathy,HIF-1α small interfere RNA pSUPERH1-siHIF1α may significantly suppress the expression of CD18 on the surface of K562 cells,but it may not significantly influence the expression of ninjurin-1 on the surface of K562 cells. Key words: Diabetic retinopathy/pathophsiology; Hypoxia-inducible factor 1, alpha subunit; RNA, small interfering

Expression of hypoxia-inducible factor 1 alpha and oligodendrocyte lineage gene-1 in cultured brain slices after oxygen-glucose deprivation.

Oligodendrocyte lineage gene-1 expressed in oligodendrocytes may trigger the repair of neuronal myelin impairment, and play a crucial role in myelin repair. Hypoxia-inducible factor 1α, a transcription factor, is of great significance in premature infants with hypoxic-ischemic brain damage. There is little evidence of direct regulatory effects of hypoxia-inducible factor 1α on oligodendrocyte lineage gene-1. In this study, brain slices of Sprague-Dawley rats were cultured and subjected to oxygen-glucose deprivation. Then, slices were transfected with hypoxia-inducible factor 1α or oligodendrocyte lineage gene-1. The expression levels of hypoxia-inducible factor 1α and oligodendrocyte lineage gene-1 were significantly up-regulated in rat brains prior to transfection, as detected by immunohistochemical staining. Eight hours after transfection of slices with hypoxia-inducible factor 1α, oligodendrocyte lineage gene-1 expression was upregulated, and reached a peak 24 hours after transfection. Oligodendrocyte lineage gene-1 transfection induced no significant differences in hypoxia-inducible factor 1α levels in rat brain tissues with oxygen-glucose deprivation. These experimental findings indicate that hypoxia-inducible factor 1α can regulate oligodendrocyte lineage gene-1 expression in hypoxic brain tissue, thus repairing the neural impairment.

Effects of hypoxia-inducible factor 1α on bone conduction impairment in otitis media with effusion

Conclusion: Elevated levels of hypoxia-inducible factor 1α (HIF-1α) in middle ear effusion may play an important role in the pathogenesis of bone conduction impairment associated with otitis media with effusion (OME). The mechanism may be related to the up-regulation of nitric oxide (NO) expression. Objectives: This study was undertaken to investigate the role of HIF-1α in the pathogenesis of sensorineural hearing loss associated with OME. Methods: One hundred and eight OME patients were divided into two groups: OME without bone conduction impairment (group 1) and OME with bone conduction impairment (group 2). The levels of HIF-1α, NO, and quinolinic acid (QUIN) in the middle ear effusion and serum of these patients were investigated. The relationship between these factors and the bone conduction threshold (BCT) differences were analyzed. Results: The levels of HIF-1α and NO concentrations in the middle ear effusion were found to be significantly higher in group 2 than in group 1 (both p < 0.05). The OME patients' BCT differences at 4000 Hz were correlated with the levels of HIF-1α and the NO concentrations in the middle ear effusion. Furthermore, the HIF-1α levels were correlated with the levels of NO but not with the levels of QUIN in the effusion.

Effects of hypoxia inducible factor-1α activator on the biological behavior of endothelial progenitor cells

Objective To investigate the effects of hypoxia inducible factor-1α （HIF-1α） on the proliferation, migration and angiogenesis of bone marrow-derived endothelial progenitor cells （EPCs）. Methods Bone marrow EPCs were interfered with the HIF-1α activator, dimethyloxalylglycine （DMOG） at different concentrations. Methyl thiazol tetrazolium （MTT） assay, CFU assay and Western blotting were employed. Nitric oxide （NO） production, vascular endothelial growth factor （ VEGF）, stromal cell derived factor 1 （SDF-1）, migratory capacity, cellular senescence levels and angiogenesis ability were evaluated. Results DMOG could significantly activate the expression of HIF-1α protein in EPCs and increase the cell viability in a dose-dependent fashion, which at peak proliferation at concentration of 500 μmol/L. DMOG could substantially improve the colony-forming ability （P 〈 0. 01 ） and significantly protect EPCs from cellular senescence （P 〈 0. 05 ）. Besides, DOMG ameliorated the migratory functions and angiogenesis ability of EPCs. Conclusion DMOG can activate HIF-1α and act on EPCs to improve the proliferation, migration capacities and angiogenesis ability. Key words: Endothelial progenitor ceils ; Dimethyloxalylglycine ; Hypoxia inducible factor-1α; Angiogenesis

Effects of hypoxia inducible factor-1α with high expression mediated by hypoxia precondition on the JNK signaling pathway in rats received orthotopic liver autotransplantation

Objective To investigate the expression of hypoxia inducible factor-1α(HIF-1α)in the transplanted liver in rats and the role of HIF-1α in the JNK signaling pathway.Methods Ninety-six SD rats were randomly divided into normal control(NC)group,autotransplantation(AT)group,hypoxia preconditioning (HP)+ AT group according to simple random sampling method.No treatment was applied to the rats in the NC group except for blood vessel separation.Stable rat models of 70％ AT was established in the AT group.Rats in the HP + AT group were given 8％ oxygen mixed gas for 90 minutes before the operation.The levels of alanine aminotransferase(ALT)and aspartate aminotransferase(AST)were detected at 1,2,12,24 hours after operation,and the expression of HIF-1α in the hepatic tissue,mRNA expression of c-Jun,and protein expression of Cleaved Caspase-3 were detected by immunohistochemical staining,reverse transcription-polymerase chain reaction and Western blot,respectively.All data were analyzed using the analysis of variance or t test.Results The levels of ALT and AST in the HP + AT group were significantly lower than those in the AT group,while higher than those in the NC group at 1,2,12 and 24 hours after the operation(F=2631.371,1177.642,810.383,682.848;743.618,1095.522,375.995,580.613,P ＜0.05).The protein expression levels of HIF-1α in the AT group were significantly lower than those in the HP + AT group,but higher than those in the NC group at 1,2,12 and 24 hours after operation(F = 191.737,284.482,459.419,213.782,P ＜ 0.05).The mRNA expression levels of c-Jun in the HP + AT group were significantly lower than those in the AT group,while higher than those in the NC group at 1,2 and 12 hours after operation(F = 66.211,53.169,9.645,P ＜ 0.05).There was no significant difference in the mRNA expression of c-Jun among the 3 groups at 24 hours after operation(F = 1.100,P ＞ 0.05).The protein expressions of Cleaved Caspase-3 in the HP + AT group were significantly lower than those in the AT group,while higher than those in the NC group at 1,2,12 and 24 hours after the operation(F =23.133,31.158,14.347,29.043,P ＜ 0.05).Conclusion High expression of HIF-1α after HP inhibits apoptosis of hepatic cells and alleviates ischemia reperfusion injury of hepatic tissues by suppressing JNK activation,down-regulating protein expression of Cleaved Caspase-3 after orthotopic liver transplantation in rats. Key words: Liver transplantation,autologous; Hypoxia inducible factor-1α; c-Jun N-terminal kinase; Caspase-3; Ischemia reperfusion injury

Effects of hypoxia-inducible factor-1α on human gastric cancer cell apoptosis under in vitro CO(2) pneumoperitoneum environment

To study the effect of hypoxia-inducible factor-1α (HIF-1α) on human gastric cancer cells apoptosis in simulated CO2 pneumoperitoneum environment. Applied closed box to simulated CO2 pneumoperitoneum environment under the pressure of 0, 5, 10 and 15 mm Hg (1 mm Hg = 0.133 kPa). Compared HIF-1α mRNA and protein expression of MKN-45 cells before and after silencing HIF-1α by RT-PCR and Western blot. Study the changes of bcl-2/bax expression in MKN-45 cells before and after silencing HIF-1α by immunohistochemistry. The apoptosis ratio of MKN-45 was measured by using Annexin V-FITC/PI double labelled staining. In 15 mm Hg group, HIF-1α mRNA and protein expression of MKN-45 cells (1.48 ± 0.22, 1.34 ± 0.09) and HIF-1α protein expression in 10 mm Hg group (1.25 ± 0.10) were significantly higher than those in control group (0.55 ± 0.17, 0.83 ± 0.04) (P < 0.05). But there was no significant differences among 0, 5, 10 mm Hg group and control group in HIF-1α mRNA (P > 0.05); and no obvious difference was found among 0, 5 mm Hg group and the control group in HIF-1α protein expression (P > 0.05). In 15 mm Hg CO2 pressure, bcl-2/bax expression (0.78 ± 0.05) was obviously lower than that in the control group (1.43 ± 0.15) (P < 0.05) and the apoptosis ratio (11.70 ± 0.12) was significantly higher than the control group (0.22 ± 0.07) (P < 0.01) before silencing HIF-1α. But once HIF-1α was silenced, HIF-1α mRNA (0.52 ± 0.11), HIF-1α protein expression (0.92 ± 0.02), bcl-2/bax ratio (1.57 ± 0.04) and apoptosis ratio (0.45 ± 0.11) in MKN-45 were not significantly different between 15 mm Hg group and the control group (P > 0.05). The apoptosis ratios of MKN-45 under 0, 5, 10 mm Hg CO2 pneumoperitoneum are comparable with that in the control group before the silencing of HIF-1α. The apoptosis ratio of MKN-45 is increased under 15 mm Hg CO2 pneumoperitoneum environment and HIF-1α may be one of the important factor to improve the apoptosis of human gastric cancer cell.