Abstract
The endothelial cell-specific mitogen vascular-endothelial growth factor (VEGF) plays a key role in both physiological and pathological angiogenesis. The up-regulation of VEGF expression in response to reduced oxygen tension occurs through transcriptional and post-transcriptional mechanisms. To investigate the molecular mechanisms of transcriptional activation by hypoxia (1% oxygen), fine mapping of a hypoxia-responsive region of the human VEGF promoter was carried out using luciferase reporter-gene constructs in C6 glioma cells. Here, we report that the binding site of hypoxia-inducible factor 1 (HIF1) is crucial for the hypoxic induction of VEGF gene expression. However, an enhancer subfragment containing the HIF1 binding site was not sufficient to confer full hypoxia responsiveness. Addition of upstream sequences restored the full sensitivity to hypoxia induction. This potentiating effect is due to activator protein 1 binding. The 'potentiating' sequences are unable to confer hypoxia responsiveness on their own. Our results strongly suggest that in C6 glioma cells a complex array of trans-acting factors facilitates full transcriptional induction of VEGF gene expression by hypoxia.
Full Text
The Full Text of this article is available as a PDF (276.0 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Arany Z., Huang L. E., Eckner R., Bhattacharya S., Jiang C., Goldberg M. A., Bunn H. F., Livingston D. M. An essential role for p300/CBP in the cellular response to hypoxia. Proc Natl Acad Sci U S A. 1996 Nov 12;93(23):12969–12973. doi: 10.1073/pnas.93.23.12969. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bunn H. F., Poyton R. O. Oxygen sensing and molecular adaptation to hypoxia. Physiol Rev. 1996 Jul;76(3):839–885. doi: 10.1152/physrev.1996.76.3.839. [DOI] [PubMed] [Google Scholar]
- Estes S. D., Stoler D. L., Anderson G. R. Normal fibroblasts induce the C/EBP beta and ATF-4 bZIP transcription factors in response to anoxia. Exp Cell Res. 1995 Sep;220(1):47–54. doi: 10.1006/excr.1995.1290. [DOI] [PubMed] [Google Scholar]
- Forsythe J. A., Jiang B. H., Iyer N. V., Agani F., Leung S. W., Koos R. D., Semenza G. L. Activation of vascular endothelial growth factor gene transcription by hypoxia-inducible factor 1. Mol Cell Biol. 1996 Sep;16(9):4604–4613. doi: 10.1128/mcb.16.9.4604. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Goldberg M. A., Gaut C. C., Bunn H. F. Erythropoietin mRNA levels are governed by both the rate of gene transcription and posttranscriptional events. Blood. 1991 Jan 15;77(2):271–277. [PubMed] [Google Scholar]
- Goldberg M. A., Schneider T. J. Similarities between the oxygen-sensing mechanisms regulating the expression of vascular endothelial growth factor and erythropoietin. J Biol Chem. 1994 Feb 11;269(6):4355–4359. [PubMed] [Google Scholar]
- Gradin K., McGuire J., Wenger R. H., Kvietikova I., fhitelaw M. L., Toftgård R., Tora L., Gassmann M., Poellinger L. Functional interference between hypoxia and dioxin signal transduction pathways: competition for recruitment of the Arnt transcription factor. Mol Cell Biol. 1996 Oct;16(10):5221–5231. doi: 10.1128/mcb.16.10.5221. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ikeda E., Achen M. G., Breier G., Risau W. Hypoxia-induced transcriptional activation and increased mRNA stability of vascular endothelial growth factor in C6 glioma cells. J Biol Chem. 1995 Aug 25;270(34):19761–19766. doi: 10.1074/jbc.270.34.19761. [DOI] [PubMed] [Google Scholar]
- Janknecht R., Hunter T. Versatile molecular glue. Transcriptional control. Curr Biol. 1996 Aug 1;6(8):951–954. doi: 10.1016/s0960-9822(02)00636-x. [DOI] [PubMed] [Google Scholar]
- Lee J. S., See R. H., Deng T., Shi Y. Adenovirus E1A downregulates cJun- and JunB-mediated transcription by targeting their coactivator p300. Mol Cell Biol. 1996 Aug;16(8):4312–4326. doi: 10.1128/mcb.16.8.4312. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Leibiger B., Walther R., Leibiger I. B. The role of the proximal CTAAT-box of the rat glucokinase upstream promoter in transcriptional control in insulin-producing cells. Biol Chem Hoppe Seyler. 1994 Feb;375(2):93–98. doi: 10.1515/bchm3.1994.375.2.93. [DOI] [PubMed] [Google Scholar]
- Levy A. P., Levy N. S., Goldberg M. A. Post-transcriptional regulation of vascular endothelial growth factor by hypoxia. J Biol Chem. 1996 Feb 2;271(5):2746–2753. doi: 10.1074/jbc.271.5.2746. [DOI] [PubMed] [Google Scholar]
- Levy A. P., Levy N. S., Wegner S., Goldberg M. A. Transcriptional regulation of the rat vascular endothelial growth factor gene by hypoxia. J Biol Chem. 1995 Jun 2;270(22):13333–13340. doi: 10.1074/jbc.270.22.13333. [DOI] [PubMed] [Google Scholar]
- Liu Y., Cox S. R., Morita T., Kourembanas S. Hypoxia regulates vascular endothelial growth factor gene expression in endothelial cells. Identification of a 5' enhancer. Circ Res. 1995 Sep;77(3):638–643. doi: 10.1161/01.res.77.3.638. [DOI] [PubMed] [Google Scholar]
- Prabhakar N. R., Shenoy B. C., Simonson M. S., Cherniack N. S. Cell selective induction and transcriptional activation of immediate early genes by hypoxia. Brain Res. 1995 Oct 30;697(1-2):266–270. doi: 10.1016/0006-8993(95)00994-2. [DOI] [PubMed] [Google Scholar]
- Rondon I. J., Scandurro A. B., Wilson R. B., Beckman B. S. Changes in redox affect the activity of erythropoietin RNA binding protein. FEBS Lett. 1995 Feb 13;359(2-3):267–270. doi: 10.1016/0014-5793(95)00066-i. [DOI] [PubMed] [Google Scholar]
- Rupec R. A., Baeuerle P. A. The genomic response of tumor cells to hypoxia and reoxygenation. Differential activation of transcription factors AP-1 and NF-kappa B. Eur J Biochem. 1995 Dec 1;234(2):632–640. doi: 10.1111/j.1432-1033.1995.632_b.x. [DOI] [PubMed] [Google Scholar]
- Schuster S. J., Badiavas E. V., Costa-Giomi P., Weinmann R., Erslev A. J., Caro J. Stimulation of erythropoietin gene transcription during hypoxia and cobalt exposure. Blood. 1989 Jan;73(1):13–16. [PubMed] [Google Scholar]
- Schüle R., Umesono K., Mangelsdorf D. J., Bolado J., Pike J. W., Evans R. M. Jun-Fos and receptors for vitamins A and D recognize a common response element in the human osteocalcin gene. Cell. 1990 May 4;61(3):497–504. doi: 10.1016/0092-8674(90)90531-i. [DOI] [PubMed] [Google Scholar]
- Semenza G. L., Wang G. L. A nuclear factor induced by hypoxia via de novo protein synthesis binds to the human erythropoietin gene enhancer at a site required for transcriptional activation. Mol Cell Biol. 1992 Dec;12(12):5447–5454. doi: 10.1128/mcb.12.12.5447. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wang G. L., Jiang B. H., Rue E. A., Semenza G. L. Hypoxia-inducible factor 1 is a basic-helix-loop-helix-PAS heterodimer regulated by cellular O2 tension. Proc Natl Acad Sci U S A. 1995 Jun 6;92(12):5510–5514. doi: 10.1073/pnas.92.12.5510. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Whitelaw M., Pongratz I., Wilhelmsson A., Gustafsson J. A., Poellinger L. Ligand-dependent recruitment of the Arnt coregulator determines DNA recognition by the dioxin receptor. Mol Cell Biol. 1993 Apr;13(4):2504–2514. doi: 10.1128/mcb.13.4.2504. [DOI] [PMC free article] [PubMed] [Google Scholar]