Role of ROS/Kv/HIF Axis in the Development of Hypoxia-Induced Pulmonary Hypertension

Hypoxic pulmonary hypertension (HPH) is a common complication in patients with chronic obstructive pulmonary disease (COPD), sleep-disordered breathing, or dwellers in high altitude. The exact mechanisms underlying the development of HPH still remain unclear. Reactive oxygen species (ROS),hypoxia inducible factors (HIF), and potassium channels (KV) are believed as the main factors during the development of HPH. We propose that the “ROS/Kv/HIF axis” may play an important initiating role in the development of HPH. Being formed under a hypoxic condition, ROS affects the expression and function of HIFs or KV, and consequently triggers multiple downstream signaling pathways and genes expression that participate in promoting pulmonary vasoconstriction and arterial remodeling. Thus, further study determining the initiating role of “ROS/Kv/HIF axis” in the development of HPH could provide theoretic evidences to better understand the underlying mechanisms of HPH, and help identify new potential targets in the treatment of HPH.

Hypoxia inducible factor-1alpha mediates protection of DL-3-n-butylphthalide in brain microvascular endothelial cells against oxygen glucose deprivation-induced injury

Studies have demonstrated that DL-3-n-butylphthalide can significantly alleviate oxygen glucose deprivation-induced injury of human umbilical vein endothelial cells at least partly associated with its enhancement on oxygen glucose deprivation-induced hypoxia inducible factor-1α expression.In this study,we hypothesized that DL-3-n-butylphthalide can protect against oxygen glucose deprivation-induced injury of newborn rat brain microvascular endothelial cells by means of upregulating hypoxia inducible factor-1α expression.MTT assay and Hoechst staining results showed that DL-3-n-butylphthalide protected brain microvascular endothelial cells against oxygen glucose deprivation-induced injury in a dose-dependent manner.Western blot and immunofluorescent staining results further confirmed that the protective effect was related to upregulation of hypoxia inducible factor-1α.Real-time RT-PCR reaction results showed that DL-3-n-butylphthalide reduced apoptosis by inhibiting downregulation of pro-apoptotic gene caspase-3 mRNA expression and upregulation of apoptosis-executive protease bcl-2 mRNA expression;however,DL-3-n-butylphthalide had no protective effects on brain microvascular endothelial cells after knockdown of hypoxia inducible factor-1α by small interfering RNA.These findings suggest that DL-3-n-butylphthalide can protect brain microvascular endothelial cells against oxygen glucose deprivation-induced injury by upregulating bcl-2 expression and downregulating caspase-3 expression though hypoxia inducible factor-1α pathway.

DI-3-n-butylphthalide exerts neuroprotective effects by modulating hypoxia-inducible factor 1-alpha ubiquitination to attenuate oxidative stress-induced apoptosis

DI-3-n-butylphthalide is used to treat mild and moderate acute ischemic stroke.However,the precise underlying mechanism requires further investigation.In this study,we investigated the molecular mechanism of DI-3-n-butylphthalide action by various means.We used hydrogen peroxide to induce injury to PC12cells and RAW264.7 cells to mimic neuronal oxidative stress injury in stroke in vitro and examined the effects of DI-3-n-butylphthalide.We found that DI-3-nbutylphthalide pretreatment markedly inhibited the reduction in viability and reactive oxygen species production in PC12 cells caused by hydrogen peroxide and inhibited cell apoptosis.Furthermore,DI-3-n-butylphthalide pretreatment inhibited the expression of the pro-apoptotic genes Bax and Bnip3.DI-3-nbutylphthalide also promoted ubiquitination and degradation of hypoxia inducible factor 1α,the key transcription factor that regulates Bax and Bnip3 genes.These findings suggest that DI-3-n-butylphthalide exhibits a neuroprotective effect on stroke by promoting hypoxia inducible factor-1α ubiquitination and degradation and inhibiting cell apoptosis.

Human umbilical cord mesenchymal stem cells derivedexosomes on VEGF-A in hypoxic-induced mice retinal astrocytes and mice model of retinopathy of prematurity

AIM:To observe the effect of human umbilical cord mesenchymal stem cells(hUCMSCs)secretions on the relevant factors in mouse retinal astrocytes,and to investigate the effect of hUCMSCs on the expression of vascular endothelial growth factor-A(VEGF-A)and to observe the therapeutic effect on the mouse model of retinopathy of prematurity(ROP).METHODS:Cultured hUCMSCs and extracted exosomes from them and then retinal astrocytes were divided into control group and hypoxia group.MTT assay,flow cytometry,reverse transcription-polymerase chain reaction(RT-PCR)and Western blot were used to detect related indicators.Possible mechanisms by which hUCMSCs exosomes affect VEGF-A expression in hypoxia-induced mouse retinal astrocytes were explored.At last,the efficacy of exosomes of UCMSCs in a mouse ROP model was explored.Graphpad6 was used to comprehensively process data information.RESULTS:The secretion was successfully extracted from the culture supernatant of hUCMSCs by gradient ultracentrifugation.Reactive oxygen species(ROS)and hypoxia inducible factor-1α(HIF-1α)of mice retinal astrocytes under different hypoxia time and the expression level of VEGF-A protein and VEGF-A mRNA increased,and the ROP cell model was established after 6h of hypoxia.The secretions of medium and high concentrations of hUCMSCs can reduce ROS and HIF-1α,the expression levels of VEGF-A protein and VEGF-A mRNA are statistically significant and concentration dependent.Compared with the ROP cell model group,the expression of phosphatidylinositol 3-kinase(PI3K)/protein kinase B(AKT)/mammalian target of rapamycin(mTOR)signal pathway related factors in the hUCMSCs exocrine group is significantly decreased.The intravitreal injection of the secretions of medium and high concentrations of hUCMSCs can reduce VEGF-A and HIF-1αin ROP model tissues.HE staining shows that the number of retinal neovascularization in ROP mice decreases with the increase of the dose of hUCMSCs secretion.CONCLUSION:In a hypoxia induced mouse retinal astrocyte model,hUCMSCs exosomes are found to effectively reduce the expression of HIF-1αand VEGF-A,which are positively correlated with the concentration of hUCMSCs exosomes.HUCMSCs exosomes can effectively reduce the number of retinal neovascularization and the expression of HIF-1αand VEGF-A proteins in ROP mice,and are positively correlated with drug dosage.Besides,they can reduce the related factors on the PI3K/AKT/mTOR signaling pathway.

Is the hypoxia-inducible factor-1 alpha mRNA expression activated by ethanol-induced injury, the mechanism underlying alcoholic liver disease?

BACKGROUND: Excessive alcohol consumption can result in multiple organ injury, of which alcoholic liver disease (ALD) is the most common. With economic development and improvement of living standards, the incidence of diseases caused by alcohol abuse has been increasing in China, although its pathogenesis remains obscure. The aim of this study was to investigate the role of hypoxia in chronic ALD. METHODS: Twenty-eight male Sprague-Dawley rats were randomized into a control group (n=12) with a normal history and an experimental group (n=16) fed with 10 ml/ kg of 56% (vol/vol) ethanol once per day by gastric lavage for 24 weeks. At 24 weeks, blood samples were collected and then the rats were killed. Liver samples were frozen at -80 ℃ and used for RT-PCR; other liver samples were obtained for immunohistochemical staining. RESULTS: When the period of alcohol consumption increased, the positive rate of expression of hypoxia- inducible factor-1 alpha (HIF-1α) mRNA was more significantly elevated in the liver of the alcohol group than in the control group (P≤0.05). The HIF-1α protein located in the cytoplasm was seldom expressed in the control group, but significantly in the alcohol group (P≤0.01). CONCLUSION: HIF-1α mRNA expression was activated by ethanol-induced injury in this study, suggesting that hypoxia is involved in the underlying mechanism of ALD.

Effect of NADPH Oxidase Inhibitor Apocynin on the Expression of Hypoxia-induced Factor-1α and Endothelin-1 in Rat Carotid Body Exposed to Chronic Intermittent Hypoxia

The effects of nicotinamide adenine dinucleotide phosphate （NADPH） oxidase inhibitor apocynin on the enhanced hypoxia induced factor-let （HIF-lct） and endothelin-1 （ET-1） expression, elevated systolic blood pressure under chronic intermittent hypoxia （CIH） condition and its action mechanism were investigated. Thirty healthy 8-week old Sprague-Dawley （SD） male rats were randomly divided into three groups （n=10 each）： sham group, CIH group, and apocynin-treated CIH group. Tail artery systolic blood pressure was measured by tail-cuff method. Real-time fluorescence quantitative polymerase chain reaction （PCR） was used to detect the mRNA expression of HIF-lu and ET-1 in the carotid body, and the HIF-1a protein expression was examined by using Western blotting. The levels of malondialdehyde （MDA） and superoxide dismutase （SOD） were determined by using colorimetric method. In addition, the plasma ET-1 and HIF-1a levels were measured by using enzyme-linked immunosorbent assay. It was found that CIH exposure was associated with increased MDA levels, and apo- cynin-treated CIH animals showed reduction in MDA levels. Apocynin treatment prevented CIH-induced hypertension as well as CIH-induced decrease in SOD. The increases of HIF-1a and ET-1 mRNA along with HIF-la protein expression in the carotid body, and elevated circulating HIF-1a and ET-1 levels were observed in CIH-exposed animals. Treatment with apocynin significantly decreased the ET-1 mRNA, HIF-lct protein expression and circulating HIF-la level in CIH-exposed animals, and there was no statistically significant difference in the HIF-lu mRNA expression between CIH group and apo- cynin-treated group. These results indicated that apocynin alleviated CIH-induced hypertension by inhibiting NADPH oxidase, further leading to the reduced vasoconstrictor ET-1 level and oxidative stress. HIF-1a/ET-1 system signal pathway may interact with CIH-induced NADPH oxidase-dependent oxidative stress. Inhibition of NADPH oxidase activity may hopefully serve as a useful strategy for prevention and treatment of obstructive sleep apnea hypopnea syndrome-induced hypertension.

Transfer of mitochondria from mesenchymal stem cells derived from induced pluripotent stem cells attenuates hypoxia-ischemia-induced mitochondrial dysfunction in PC12 cells

Mitochondrial dysfunction in neurons has been implicated in hypoxia-ischemia-induced brain injury.Although mesenchymal stem cell therapy has emerged as a novel treatment for this pathology,the mechanisms are not fully understood.To address this issue,we first co-cultured 1.5×10^5 PC12 cells with mesenchymal stem cells that were derived from induced pluripotent stem cells at a ratio of 1:1,and then intervened with cobalt chloride(CoCl2)for 24 hours.Reactive oxygen species in PC12 cells was measured by Mito-sox.Mitochondrial membrane potential(ΔΨm)in PC12 cells was determined by JC-1 staining.Apoptosis of PC12 cells was detected by terminal deoxynucleotidal transferase-mediated dUTP nick end-labeling staining.Mitochondrial morphology in PC12 cells was examined by transmission electron microscopy.Transfer of mitochondria from the mesenchymal stem cells derived from induced pluripotent stem cells to damaged PC12 cells was measured by flow cytometry.Mesenchymal stem cells were induced from pluripotent stem cells by lentivirus infection containing green fluorescent protein in mitochondria.Then they were co-cultured with PC12 cells in Transwell chambers and treated with CoCl2 for 24 hours to detect adenosine triphosphate level in PC12 cells.CoCl2-induced PC12 cell damage was dose-dependent.Co-culture with mesenchymal stem cells significantly reduced apoptosis and restoredΔΨm in the injured PC12 cells under CoCl2 challenge.Co-culture with mesenchymal stem cells ameliorated mitochondrial swelling,the disappearance of cristae,and chromatin margination in the injured PC12 cells.After direct co-culture,mitochondrial transfer from the mesenchymal stem cells stem cells to PC12 cells was detected via formed tunneling nanotubes between these two types of cells.The transfer efficiency was greatly enhanced in the presence of CoCl2.More importantly,inhibition of tunneling nanotubes partially abrogated the beneficial effects of mesenchymal stem cells on CoCl2-induced PC12 cell injury.Mesenchymal stem cells reduced CoCl2-induced PC12 cell injury and these effects were in part due to efficacious mitochondrial transfer.

Inhibition of epidermal growth factor receptor signaling protects human malignant glioma cells from hypoxia - induced cell death

Epidermal growth factor receptor(EGFR)signaling has become an importanttarget for drug development becauseEGFR signaling enhances tumor cell proliferation,migration,and invasion and inhibits apoptosis.However,theresults of clinical trials using EGFR inhibitors in patients with solid tumors have been disappointing.Here,wereport a protective effect of the EGFR inhibitors AG1478 and PD153035 against cell death induced by acute hy-poxia,which contrasts with their proapoptotic effects under normoxia.Under hypoxic conditions,both agents re-

Forskolin Modulates the Inhibitory Effect of C-Type Natriuretic Peptide on Hypoxia-Induced Atrial Dynamics and Hypoxia Inducible Factor 1 Alpha Activity

Our study investigated effects of C-type natriuretic peptide (CNP) on atrial dynamics and hypoxia inducible factor 1 alpha (HIF-1α) activity in perfused beating rat atria, under hypoxic conditions. Hypoxia significantly increased the levels of HIF-1α, concomitant with decreased trial dynamics. CNP (0.1 μmol/L) further decreased atrial dynamics under hypoxia and suppressed hypoxia-induced stimulation of HIF-1α expression. An adenylylcyclase (AC) activator, forskolin (0.1 μmol/L), significantly up-regulated atrial phosphodiesterase subtype 3A (PDE 3A) protein without affecting hypoxia-induced dynamics. In the presence of forskolin, the inhibitory effects of CNP on hypoxia-induced atrial dynamics and HIF-1α levels were significantly attenuated. Forskolin also prevented hypoxia-induced downregulation of PDE3A protein. These findings suggested that CNP inhibited atrial dynamics and HIF-1α activity in the isolated perfused beating rat atria under hypoxic conditions. Furthermore, both effects were modulated by the AC activator forskolin, through activation of CNP-PDE 3A signaling.

An inhibitor of HIF-α subunit expression suppresses hypoxiainduced dedifferentiation of human NSCLC into cancer stem cell-like cells

AIM:To investigate whether hypoxia induces dedifferentiation of non-small cell lung cancer(NSCLC) cells and whether a hypoxia-inducible factor(HIF) inhibitor is able to suppress the process.METHODS:Human lung adenocarcinoma A549 cells and squamous carcinoma QG56 cells were cultured under normoxic(21%O_2) or hypoxic(4%or 1%O_2) conditions.The expression of the following genes were examined by reverse transcription-polymerase chain reaction,Western blotting and/or immunofluorescence:HIF-1α and HIF-2αsubunits;differentiation marker genes,namely surfactant protein C(SP-C)(type Ⅱ alveolar cell marker),CC10(type I alveolar cell marker) and aquaporin 5(AQP5)(Clara cell marker);and stem cell-associated genes,namely CD133,0CT4,and Musashi-1(MSI1).The tumor sphere-forming ability of the cells was evaluated by culturing them in serum-free growth factor-rich medium containing epidermal growth factor(EGF) and fibroblast growth factor(FGF).CD133 expression in hypoxic regions in A549 tumors was examined by double-immunostaining of tissue cryosections with an anti-2-nitroimidazole EF5 antibody and an anti-CD133 antibody.The metastatic ability of A549 cells was examined macroscopically and histologically after injecting them into the tail vein of immunocompromised mice.RESULTS:A549 cells primarily expressed SP-C,and QG56 cells expressed CC10 and AQP5.Exposure of A549 cells to hypoxia resulted in a marked downregulation of SP-C and upregulation of CD133,OCT4,and MSI1 in a time-dependent manner.Moreover,hypoxia mimetics,namely desferrioxamine and cobalt chloride,elicited similar effects.Ectopic expression of the constitutively active HIF-la subunit also caused the downregulation of SP-C and upregulation of CD133 and MSI1 but not OCT4,which is a direct target of HIF-2.Hypoxia enhanced the sphere-forming activity of A549 cells in serum-free medium containing EGF and FGF.Similarly,hypoxia downregulated the expression of CC10 and AQP5 genes and upregulated CD133,OCT4,and MSI1 genes in QG56 cells.TX-402(3-amino-2-quinoxalinecarbonitrile 1,4-dioxide),which is a small molecule inhibitor of the expression of HIF-1α and HIF-2αsubunits under hypoxic conditions,inhibited the upregulation of SP-C'and hypoxia-induced down-regulation of CD133,OCT4,and MSI1.Notably,TX-402 significantly suppressed the hypoxia-enhanced lung-colonizing ability of A549 cells.CONCLUSION:Hypoxia induces the de-differentiation of NSCLC cells into cancer stem cell-like cells,and HIF inhibitors are promising agents to prevent this process.

The timing and extent of intraosseous hypoxia in the oxidative stress-induced rat osteonecrosis model

Using a rat oxidative stress-induced femoral head osteonecrosis model, we determined the presence/ absence and timing of the generation of hypoxia in the femoral head. DL-Buthionine-(S,R)-sulfoximine (BSO) 500 mg/kg was administered intraperitoneally to male Wistar rats. The rats were killed at 1, 3, 6, 12 hours, and 1, 3, 5 days after BSO administration, and the bilateral femora were removed. A group not administered BSO (control group) was also studied (each group n = 5). In the femoral heads of each group, the expression of hypoxia-inducible factor-1 alpha (HIF-1α) as an index of hypoxia was confirmed by the Western blot method, and quantified using analytical software. In the femoral head increased HIF-1α expression was found in all groups from 1 hour after BSO administration (p < 0.05). In particular, in all specimens of the group 3 hours after BSO administration the most intense expression of HIF-1α amounting to about 13-fold of that of control group was noted (p < 0.001). The present results suggested that in the extremely short period of 3 hours after BSO administration hypoxia severe enough to cause osteonecrosis was induced by oxidative stress in the rat femoral head.

Desferoxamine preconditioning protects against cerebral ischemia in rats by inducing expressions of hypoxia inducible factor 1α and erythropoietin

Objective To investigate whether desferoxamine （DFO） preconditioning can induce tolerance against cerebral ischemia and its effect on the expression of hypoxia inducible factor 1 α （HIF- 1α） and erythropoietin （EPO） in vivo and in vitro. Methods Rat model of cerebral ischemia was established by middle cerebral artery occlusion with or without DFO administration. Infarct size was examined by TTC staining, and the neurological severity score was evaluated according to published method. Cortical neurons were cultured under ischemia stress which was mimicked by oxygen-glucose deprivation （OGD）, and the neuron damage was assessed by MTT assay. Immunofluorescent staining was employed to detect the expressions of HIF-1 and EPO. Results The protective effect induced by DFO （decreasing the infarction volume and ameliorating the neurological function） appeared at 2 d after administration ofDFO （post-DFO）, lasted until 7 d and disappeared at 14 d （P 〈 0.05）; the most effective action was observed at 3 d post-DFO. DFO induced tolerance of cultured neurons against OGD： neuronal viability was increased 23%, 34%, 40%, 48% and 56% at 8 h, 12 h, 24 h, 36 h, and 48 h, respectively, post-DFO （P 〈 0.05）. Immunofluorescent staining found that HIF-1 α and EPO were upregulated in the neurons of rat brain at 3 d and 7 d post-DFO; increase of HIF-1 α and EPO appeared in cultured cortex neurons at 36 h and 48 h post-DFO. Conclusion DFO induced tolerance against focal cerebral ischemia in rats, and exerted protective effect on OGD cultured cortical neurons. DFO significant induced the expression of HIF- 1 α and EPO both in vivo and in vitro. DFO preconditioning can protect against cerebral ischemia, which may be associated with the synthesis of HIF- 1 α and EPO.

Quantitative analysis of hepatic hypoxia-inducible factor-1α and its abnormal gene expression during the formation of hepatocellular carcinoma

BACKGROUND:Hepatic hypoxia-inducible factor-1(HIF-1) is activated in the progression of hepatocellular carcinoma (HCC).This study aimed to investigate the dynamic alterations of HIF-1αand its gene expression so as to explore the relationship between HIF-1αexpression and hepatocarcinogenesis at the early stage of HCC. METHODS:A hepatoma model was made with 2-fluorenyl- acetamide(2-FAA)in male Sprague-Dawley rats.Morphological changes of rat hepatocytes were assessed pathologically (HE staining).The dynamic expression of hepatic and circulating HIF-1αwas quantitatively analyzed by ELISA. The gene fragments of hepatic HIF-1αmRNA were amplified by RT-PCR and confirmed by sequencing.The cellular distribution of hepatic HIF-1αexpression was confirmed by immunohistochemistry. RESULTS:Histological examination confirmed granulelike degeneration to atypical hyperplasia and HCC development in rat hepatocytes and progressive increases in the levels of hepatic and circulating HIF-1αand its gene expression during the course.The levels of HIF-1α expression in the liver and blood of rats with hepatoma were significantly higher than those in normal ratsand those with degeneration.Immunohistochemical analysis confirmed the positive expression and hepatocyte distribution of HIF-1αin the development of rat hepatoma. A positive relationship was found between HIF-1α expression in the liver and blood(P<0.01). CONCLUSIONS:The above observations support the hypothesis that the overexpression of HIF-1αand its gene are closely associated with the malignant transformation of hepatocytes and play an important role at the stage of hepatocarcinogenesis.

Prognostic value of hypoxia-inducible factor-1 alpha and prolyl 4-hydroxylase beta polypeptide overexpression in gastric cancer

AIM To investigate the relationship between hypoxia-inducible factor-1α(HIF-1α), prolyl 4-hydroxylase beta(P4 HB) expression, and clinicopathologic parameters, as well as the prognostic value of these genes for patients with gastric cancer(Gc).METHODS Hypoxia is a critical factor that shapes the Gc microenvironment. In previous reports, we have demonstrated that P4 HB is a potential target of HIF-1α. In the present study, gene expression profiling interactive analysis(GEPIA) was used to analyze the relationship between P4 HB and hypoxia-associated genes. To this end, 428 Gc tissue samples were used to analyze the expression of HIF-1α and P4 HB via immunohistochemical staining. Patient samples were classified as having weak-expression or over-expression both in terms of HIF-1α and P4 HB. Correlations between biomarkers and clinicopathological factors were analyzed to predict survival. RESULTS P4 HB demonstrated a positive correlation with hypoxiaassociated genes(P < 0.05). HIF-1α and P4 HB overexpression have a significant correlation with TNM staging(χ2 = 23.32, P = 0.00; χ2 = 65.64, P = 0.00) and peritoneum cavity metastasis(χ2 = 12.67, P = 0.00; χ2 = 39.29, P = 0.00). In univariate analysis, patients with a high HIF-1α expression trend had a shorter disease-free survival(DFS: 44.80 mo vs 22.06 mo) and overall survival(OS: 49.58 mo vs 39.92 mo). P4 HB overexpression reflected similar results: patients with over-expression of P4 HB had a shorter survival time than those with weak-expression(DFS: 48.03 mo vs 29.64 mo, OS: 52.48 mo vs 36.87 mo). Furthermore, HIF-1α is also a clinicopathological predictor of dismal prognosis according to multivariate analysis(DFS, 95%c I: 0.52-0.88, P < 0.00; OS, 95%c I: 0.50-0.85, P < 0.00). However, P4 HB was meaningful in DFS(95%c I: 0.58-1.00, P < 0.05) but not in OS(95%c I: 0.72-1.23, P > 0.05).CONCLUSION Overexpression of HIF-1α and P4 HB is associated with poor prognosis in patients with Gc. Thus, these genes may be potential prognostic biomarker candidates in GC.

Hypoxia inducible factor-1αaccumulation in steatotic liver preservation:Role of nitric oxide

AIM:To examine the relevance of hypoxia inducible factor(HIF-1)and nitric oxide(NO)on the preservation of fatty liver against cold ischemia-reperfusion injury(IRI). METHODS:We used an isolated perfused rat liver model and we evaluated HIF-1αin steatotic and non-steatotic livers preserved for 24 h at 4℃in University of Wisconsin and IGL-1 solutions,and then subjected to 2 h of normothermic reperfusion.After normoxic reperfusion,liver enzymes,bile production,bromosulfophthalein clearance,as well as HIF-1αand NO[endothelial NO synthase(eNOS)activity and nitrites/nitrates]were also measured.Other factors associated with the higher susceptibility of steatotic livers to IRI,such as mitochondrial damage and vascular resistance were evaluated. RESULTS:A significant increase in HIF-1αwas found in steatotic and non-steatotic livers preserved in IGL-1 after cold storage.Livers preserved in IGL-1 showed a significant attenuation of liver injury and improvement in liver function parameters.These benefits were enhanced by the addition of trimetazidine(an antiischemic drug),which induces NO and eNOS activation, to IGL-1 solution.In normoxic reperfusion,the presence of NO favors HIF-1αaccumulation,promoting also the activation of other cytoprotective genes,such as hemeoxygenase-1. CONCLUSION:We found evidence for the role of the HIF-1α/NO system in fatty liver preservation,especially when IGL-1 solution is used.

Metabolic shift in liver: Correlation between perfusion temperature and hypoxia inducible factor-1α

AIM: To study at what temperature the oxygen carried by the perfusate meets liver requirements in a model of organ perfusion. METHODS: in this study, we correlated hypoxia induciblefactor(Hi F)-1α expression to the perfusion temperature and the hepatic oxygen uptake in a model of isolated perfused rat liver. Livers from Wistar rats were perfused for 6 h with an oxygenated medium at 10, 20, 30 and 37 ℃. Oxygen uptake was measured by an oxygen probe; lactate dehydrogenase activity, lactate release and glycogen were measured spectrophotometrically; bile flow was gravitationally determined; p H of the perfusate was also evaluated; Hi F-1α m RNA and protein expression were analyzed by real time-polymerase chain reaction and ELi SA, respectively. RESULTS: Livers perfused at 10 and 20 ℃ showed no difference in lactate dehydrogenase release after 6 h of perfusion(0.96 ± 0.23 vs 0.93 ± 0.09 m U/min per g) and had lower hepatic damage as compared to 30 and 37 ℃(5.63 ± 0.76 vs 527.69 ± 45.27 m U/min per g, respectively, P s < 0.01). After 6 h, tissue ATP was significantly higher in livers perfused at 10 and 20 ℃than in livers perfused at 30 and 37 ℃(0.89 ± 0.06 and 1.16 ± 0.05 vs 0.57 ± 0.09 and 0.33 ± 0.08 nmol/mg, respectively, P s < 0.01). No sign of hypoxia was observed at 10 and 20 ℃, as highlighted by low lactate release respect to livers perfused at 30 and 37 ℃(121.4 ± 12.6 and 146.3 ± 7.3 vs 281.8 ± 45.3 and 1094.5 ± 71.7 nmol/m L, respectively, P s < 0.02), and low relative Hi F-1α m RNA(0.40 ± 0.08 and 0.20 ± 0.03 vs 0.60 ± 0.20 and 1.47 ± 0.30, respectively, P s < 0.05) and protein(3.72 ± 0.16 and 3.65 ± 0.06 vs 4.43 ± 0.41 and 6.44 ± 0.82, respectively, P s < 0.05) expression.CONCLUSION: Livers perfused at 10 and 20 ℃ show no sign of liver injury or anaerobiosis, in contrast to livers perfused at 30 and 37 ℃.

Hypoxia upregulates hypoxia inducible factor(HIF)-3α expression in lung epithelial cells: characterization and comparison with HIF-1α

The role of the hypoxia-inducible factor(HIF)subunits 1α and 2α in response to hypoxia is well established in lungepithelial cells,whereas little is known about HIF-3α with respect to transcriptional and translational regulation by hy-poxia.HIF-3α and HIF-1α are two similar but distinct basic helix-loop-helix-PAS proteins,which have been postulatedto activate hypoxia responsive genes in response to hypoxia.Here,we used quantitative real time RT-PCR and immu-noblotting to determine the activation of HIF-3α vs.HIF-1α by hypoxia.HIF-3α was strongly induced by hypoxia(1%O_2)both at the level of protein and mRNA due to an increase in protein stability and transcriptional activation,whereasHIF-1α protein and mRNA levels enhanced transiently and then decreased because of a reduction in its mRNA stabilityin A549 cells,as measured on mRNA and protein levels.Interestingly,HIF-3α and HIF-1α exhibited strikingly similarresponses to a variety of activating or inhibitory pharmacological agents.These results demonstrate that HIF-3α is ex-pressed abundantly in lung epithelial cells,and that the transcriptional induction of HIF-3α plays an important role in theresponse to hypoxia in vitro.Our findings suggest that HIF-3α,as a member of the HIF system,is complementary ratherthan redundant to HIF-1α induction in protection against hypoxic damage in alveolar epithelial cells.

Hypoxia inducible factor-1 alpha stabilization for regenerative therapy in traumatic brain injury

Mild traumatic brain injury（TBI）, also called concussion, initiates sequelae leading to motor deficits, cognitive impairments and subtly compromised neurobehaviors. While the acute phase of TBI is associated with neuroinflammation and nitroxidative burst, the chronic phase shows a lack of stimulation of the neurorepair process and regeneration. The deficiency of nitric oxide（NO）, the consequent disturbed NO metabolome, and imbalanced mechanisms of S-nitrosylation are implicated in blocking the mechanisms of neurorepair processes and functional recovery in the both phases. Hypoxia inducible factor-1 alpha（HIF-1α）, a master regulator of hypoxia/ischemia, stimulates the process of neurorepair and thus aids in functional recovery after brain trauma. The activity of HIF-1α is regulated by NO via the mechanism of S-nitrosylation of HIF-1α. S-nitrosylation is dynamically regulated by NO metabolites such as S-nitrosoglutathione（GSNO） and peroxynitrite. GSNO stabilizes, and peroxynitrite destabilizes HIF-1α. Exogenously administered GSNO was found not only to stabilize HIF-1α and to induce HIF-1α-dependent genes but also to stimulate the regeneration process and to aid in functional recovery in TBI animals.

Effect of HIF-1αon VEGF-C Induced Lymphangiogenesis and Lymph Nodes Metastases of Pancreatic Cancer

The effect of hypoxia inducible factor-1 α （HIF-1 α） on vascular endothelial growth factor C （VEGF-C） and the correlation between HIF- 1 α and lymphangiogenesis and lymph nodes metastases （LNM） in pancreatic cancer were investigated. Immunohistochemical SP method was used to detect the protein expression of HIF-1 α and VEGF-C, and Lymphatic vessel density （LVD） was determined by stain of VEGFR-3, collagen type IV in 75 pancreatic head cancers from regional pancreatectomy （RP） during Dec. 2001 to Dec. 2003. The relationship between HIF-1α and VEGF-C, lymphangiogenesis, LNM was analyzed statistically. The results showed that the positive expression rate of HIF-1α and VEGF-C in pancreatic cancer tissues was 48.00 % （36/75） and 65.33 % （49/75） respectively. In positive group of HIF-1α, the positive rate of VEGF-C and LVD, and LVD rate was 80.56 % （29/36）, 13.22±3.76 and 88.89 % （32/36） respectively, and in negative group of HIF-10t, positive rate of VEGF-C and LVD was 51.28 % （20/39）, 5.98±2.17 and 66.67 % （26/39） respectively （P〈0.01 or P〈0.05）. It was suggested that HIF-1α could promote the expression of VEGF-C, lymphangiogenesis and LNM in pancreatic cancer.

Expression of Nerve Growth Factor and Hypoxia Inducible Factor-1α and Its Correlation with Angiogenesis in Non-Small Cell Lung Cancer

Summary： In order to investigate the expression of nerve growth factor （NGF） and hypoxia inducible factor-1α （HIF-1α） and its correlation with angiogenesis in non-small cell lung cancer （NSCLC）, paraffin-embedded tissue blocks from 20 patients with NSCLC were examined. Twenty corresponding para-cancerous lung tissue specimens were obtained to serve as a control. The expression of NGF, HIF-1α, and vascular endothelial growth factor （VEGF） in the NSCLC tissues was detected by using immunohistochemistry. The microvascular density （MVD） was determined by CD31 staining. The resuits showed that the expression levels ofNGF, HIF-1α and VEGF in the NSCLC tissues were remarkably higher than those in the para-cancerous lung tissues （P〈0.05）. There was significant difference in the MVD between the NSCLC tissues （9.19±1.43） and para-cancerous lung tissues （2.23±1.19） （P〈0.05）. There were positive correlations between NGF and VEGF, between HIF-1α and VEGF, and between NGF and HIF-1α in NSCLC tissues, with the spearman correlation coefficient being 0.588, 0.519 and 0.588, respectively. In NSCLC tissues, the MVD had a positive correlation with the three factors （P〈0.05）. Theses results suggest that NGF and HIF-1α are synergically involved in the angiogenesis of NSCLC.