• Bulletin of the Korean Chemical Society
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• v.28 no.7
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• pp.1206-1208
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• 2007

• Journal of Life Science
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• v.20 no.12
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• pp.1820-1828
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• 2010

Cobalt(II) chloride, a chemical compound with the formula$CoCl_2$, has been widely used in the treatment of anemia, as a chemical agent for the induction of hypoxia in cell cultures, and is known to activate hypoxic signaling. However, excessive exposure to cobalt is associated with several clinical conditions, including asthma, pneumonia, and hematological abnormalities, and can lead to tissue and cellular toxicity. It is also known to induce apoptosis. One of the questions was that of whether $CoCl_2$ might induce apoptosis via endoplasmic reticulum (ER) stress in neurons. To address this question, first, the level of DNA fragmentation was measured for assay of apoptotic rates using $CoCl_2$ with neuron PC12 cells. After confirmation of apoptosis inductions, under the same conditions, the expression levels of ER stress associated factors [ER chaperones Bip, calnexin, ERp72, ERp29, PDI, and ER membrane kinases (IRE1, ATF6, PERK)] were examined by RT-PCR and Western blotting. These results indicated that apoptosis is induced through activation of ER membrane kinases via ER stress. In conclusion, during induction of apoptosis through $CoCl_2$-induced hypoxia in neuron PC12 cells, ER membrane kinase of IRE1 was dominantly up-expressed, and, consecutively, TRAF2, which has been suggested to be one of the links connecting apoptosis and ER stress, was strongly up-expressed.

• Toxicological Research
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• v.25 no.4
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• pp.189-193
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• 2009

Hypoxia inducible factor $1\alpha$ (HIF-$1\alpha$) is a potential marker of carcicnogenesis since it is overexpresssed in many human cancers such as brain, breast, and uterus, and its role has implicated in tumor cell growth and metastasis. In this study, we established a stable cell line that express green fluorescence protein (GFP)-fused hypoxia inducible factor $1\alpha$ (HIF-$1\alpha$) and evaluated the potential use of this cell line for assessment of carcinogenicity of chemical toxicants. Western blot analysis as well as fluorescence measurements showed that protein-level of GFP-HIF-$1\alpha$ was significantly enhanced in a dose-dependent manner upon treatment of hypoxia mimicking agents such as dexferrioxamine and $CoCl_2$. Well-Known tumor promoters such as mitomycin and methyl methanesulfonate. significantly induced the fluorescence intensity of GFP-HIF-$1\alpha$, whereas the known negative controls such as o-anthranilic acid and benzethonium chloride, did not. These results indicate that HIF-$1\alpha$ could be a biological parameter for detection of tumor initiators/promoters and suggest that the GFP-HIF-$1\alpha$ cell line is a useful system for screening of carcinogenic toxicants.

• BMB Reports
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• v.49 no.9
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• pp.508-513
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• 2016

Hypoxia-inducible factor (HIF)-1α is a key regulator associated with tumorigenesis, angiogenesis, and metastasis. HIF-1α regulation under hypoxia has been highlighted as a promising therapeutic target in angiogenesis-related diseases. Here, we demonstrate that diacetyl atractylodiol (DAA) from Atractylodes japonica (A. japonica) is a potent HIF-1α inhibitor that inhibits the Akt signaling pathway. DAA dose-dependently inhibited hypoxia-induced HIF-1α and downregulated Akt signaling without affecting the stability of HIF-1α protein. Furthermore, DAA prevented hypoxia-mediated angiogenesis based on in vitro tube formation and in vivo chorioallantoic membrane (CAM) assays. Therefore, DAA might be useful for treatment of hypoxia-related tumorigenesis, including angiogenesis.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.297.3-298
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• 2002

A benzopyranyl derivative. KR32000. synthesized as a plausible KATP opener. has been shown to exert cardioprotective effect in vivo myocardial infarct model. In this study. we investigated whether KR32000 can produce cardioprotective effect against hypoxia- and reactive oxygen species(ROS)-induced injury in heart-derived H9c2 cells. Hypoxic injury was induced by incubating cells in anaerobic chamber (glucose-free. serum-free DMEM. 85% N2. 5% CO2. 10% H2) and oxidative stress was induced by buthionine sulfoximine(BSO). (omitted)

• Journal of Chest Surgery
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• v.42 no.5
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• pp.588-596
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• 2009

Background: To clarify the effect of hypoxia on vascular contractility, we tried to show whether hypoxia induced the release of endothelium-derived relaxing factor (EDRF) and the nature of the underlying mechanism for this release. Material and Method: Isometric contractions were observed in rabbit aorta, and the released EDRF from the rabbit aorta was bioassayed by using rabbit denuded carotid artery. The intracellular $Ca^{2+}$ concentration ($[Ca^{2+}]_i$) in the cultured rabbit aortic endothelial cells was recorded by a microfluorimeter with using Fura-2/AM. Hypoxia was evoked to the blood vessels or endothelial cells by eliminating the $O_2$ in the aerating gases in the external solution. Chemical hypoxia was evoked by applying deoxyglucose or $CN^-$. Result: Hypoxia relaxed the precontracted rabbit thoracic aorta that had its endothelium, and the magnitude of the relaxation was gradually increased by repetitive bouts of hypoxia. In contrast, hypoxia-induced relaxation was not evoked in the aorta that was denuded of endothelium. In a bioassay experiment, hypoxia released endothelium-derived relaxing factor (EDRF) and the release was inhibited by L-NAME or the $K^+$ channel blocker tetraethylammonium (TEA). In the cultured endothelial cells, hypoxia augmented the ATP-induced increase of the intracellular $Ca^{2+}$ concentration ($[Ca^{2+}]_i$) and this increase was inhibited by TEA. Furthermore, chemical hypoxia also increased the $Ca^{2+}$ influx. Conclusion: From these results, it can be concluded that hypoxia might induce the release of NO from rabbit aortic endothelial cells by increasing $[[Ca^{2+}]_i$.

• Animal Bioscience
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• v.37 no.1
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• pp.28-38
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• 2024

Objective: Tibetan chickens, which have unique adaptations to extreme high-altitude environments, exhibit phenotypic and physiological characteristics that are distinct from those of lowland chickens. However, the mechanisms underlying hypoxic adaptation in the liver of chickens remain unknown. Methods: RNA-sequencing (RNA-Seq) technology was used to assess the differentially expressed genes (DEGs) involved in hypoxia adaptation in highland chickens (native Tibetan chicken [HT]) and lowland chickens (Langshan chicken [LS], Beijing You chicken [BJ], Qingyuan Partridge chicken [QY], and Chahua chicken [CH]). Results: A total of 352 co-DEGs were specifically screened between HT and four native lowland chicken breeds. Gene ontology and Kyoto encyclopedia of genes and genomes enrichment analyses indicated that these co-DEGs were widely involved in lipid metabolism processes, such as the peroxisome proliferator-activated receptors (PPAR) signaling pathway, fatty acid degradation, fatty acid metabolism and fatty acid biosynthesis. To further determine the relationship from the 352 co-DEGs, protein-protein interaction network was carried out and identified eight genes (ACSL1, CPT1A, ACOX1, PPARC1A, SCD, ACSBG2, ACACA, and FASN) as the potential regulating genes that are responsible for the altitude difference between the HT and other four lowland chicken breeds. Conclusion: This study provides novel insights into the molecular mechanisms regulating hypoxia adaptation via lipid metabolism in Tibetan chickens and other highland animals.

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.695-703
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• 2006

The dissolved oxygen level of any cell culture environment has a critical effect on cellular metabolism. Specifically, hypoxia condition decreases cell viability and recombinant protein productivity. In this work, to develop CHO cells producing recombinant protein with high productivity, mammalian expression vectors containing a human tissue-type plasminogen activator (t-PA) gene with hypoxia response element (HRE) were constructed and stably transfected into CHO cells. CHO/2HRE-t-PA cells produced 2-folds higher recombinant t-PA production than CHO/t-PA cells in a $Ba^{2+}-alginate$ immobilized culture, and 16.8-folds in a repeated batch culture. In a non-aerated batch culture of suspension-adapted cells, t-PA productivity of CHO/2HRE/t-PA cells was 4.2-folds higher than that of CHO/t-PA cells. Our results indicate that HRE is a useful tool for the enhancement of protein productivity in mammalian cell cultures.

• Journal of Life Science
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• v.23 no.11
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• pp.1342-1350
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• 2013

We examined the effect of hydrogen sulfide ($H_2S$) in chemical hypoxia-induced injury in mouse hepatocytes. Cell viability was significantly decreased by cobalt chloride ($CoCl_2$), a well-known hypoxia mimetic agent in a time- and dose- dependent manner. Sodium hydrosulfide (NaHS, a donor of $H_2S$) pretreatment before exposure to $CoCl_2$ significantly attenuated the $CoCl_2$-induced decrease of cell viability. $CoCl_2$ treatment resulted in an increase of intracellular ROS generation, which is inhibited by NaHS or N-acetyl-cysteine (NAC, a ROS scavenger), and p38 MAPK phosphorylation, which is also blocked by NaHS or NAC. The $CoCl_2$-induced increase of the Bax/Bcl-2 ratio was attenuated by NaHS, NAC, and SB 203580 (p38 MAPK inhibitor). The $CoCl_2$-induced decrease of cell viability was also attenuated by NaHS, NAC, and SB 203580 pretreatment. Additionally, NaHS inhibited the $CoCl_2$-induced COX-2. Similar to the effect of NaHS, NAC blocked $CoCl_2$-induced COX-2 expression. Furthermore, NS-398 (a selective COX-2 inhibitor) attenuated not only the $CoCl_2$-induced increase of the Bax/Bcl-2 ratio, it also decreased cell viability. Taken together, $H_2S$ protects primary cultured mouse hepatocytes against $CoCl_2$-induced cell injury through inhibition of the ROS-activated p38 MAPK cascade and the COX-2 pathway.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2000.12a
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• pp.48-48
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• 2000