Intracellular ascorbate enhances hypoxia-inducible factor (HIF)-hydroxylase activity and preferentially suppresses the HIF-1 transcriptional response
| Autor: | Gabi U. Dachs, Caroline Kuiper, Margreet C.M. Vissers, Margaret J. Currie |
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| Rok vydání: | 2014 |
| Předmět: |
Transcriptional Activation
Vascular Endothelial Growth Factor A Hypoxia-Inducible Factor 1 Cell Survival Iron Procollagen-Proline Dioxygenase Ascorbic Acid Biology Biochemistry Jurkat Cells Transcription (biology) Catalytic Domain Proto-Oncogene Proteins Physiology (medical) Gene expression Humans chemistry.chemical_classification Protein Stability Membrane Proteins Hypoxia-Inducible Factor 1 alpha Subunit Cell Hypoxia Enzyme Gene Expression Regulation Hypoxia-inducible factors chemistry Transcription preinitiation complex Protein stabilization Intracellular |
| Zdroj: | Free Radical Biology and Medicine. 69:308-317 |
| ISSN: | 0891-5849 |
| DOI: | 10.1016/j.freeradbiomed.2014.01.033 |
| Popis: | Hypoxia-inducible factor (HIF)-1 drives the transcription of hundreds of genes to support cell survival under conditions of microenvironmental and metabolic stress. HIF-1 is downregulated by iron-containing 2-oxoglutarate-dependent enzymes that require ascorbate as a cofactor. The HIF hydroxylases control both protein stability and the formation of an active transcription complex and, consequently, ascorbate could affect HIF-1α stabilization and/or gene expression, but the relative effect of ascorbate on these separate processes has not been well characterized. In this study we examined the effects of known intracellular ascorbate concentrations on both processes in response to various means of hydroxylase inhibition, including CoCl2, NiCl2, desferrioxamine, dimethyloxalylglycine, and hypoxia. Ascorbate inhibited HIF-1 activity most dramatically with all mechanisms of iron competition. In addition, HIF-1-dependent gene expression was effectively prevented by ascorbate and was inhibited even under conditions that allowed HIF-1α protein stabilization. This suggests that (1) ascorbate acts primarily to stabilize and reduce the iron atom in the hydroxylase active site and (2) the asparagine hydroxylase controlling HIF-1 transcriptional activity is particularly susceptible to fluctuations in intracellular ascorbate. These findings suggest that ascorbate plays a significant role in supporting HIF-hydroxylase function and that it could thereby modulate the cell survival response. |
| Databáze: | OpenAIRE |
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