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Hypoxia preconditioning protection of corneal stromal cells requires HIF1alpha but not VEGF.
- Source :
-
Molecular vision [Mol Vis] 2009 May 18; Vol. 15, pp. 1020-7. Date of Electronic Publication: 2009 May 18. - Publication Year :
- 2009
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Abstract
- Purpose: Hypoxia preconditioning protects corneal stromal cells from stress-induced death. This study determined whether the transcription factor HIF-1alpha (Hypoxia Inducible Factor) is responsible and whether this is promulgated by VEGF (Vascular Endothelial Growth Factor).<br />Methods: Cultured bovine stromal cells were preconditioned with hypoxia in the presence of cadmium chloride, a chemical inhibitor of HIF-1alpha, and HIF-1alpha siRNA to test if HIF-1alpha activity is needed for hypoxia preconditioning protection from UV-irradiation induced cell death. TUNEL assay was used to detect cell apoptosis after UV-irradiation. RT-PCR and western blot were used to detect the presence of HIF-1alpha and VEGF in transcriptional and translational levels.<br />Results: During hypoxia (0.5% O2), 5 muM cadmium chloride completely inhibited HIF-1alpha expression and reversed the protection by hypoxia preconditioning. HIF-1alpha siRNA (15 nM) reduced HIF-1alpha expression by 90% and produced a complete loss of protection provided by hypoxia preconditioning. Since VEGF is induced by hypoxia, can be HIF-1alpha dependent, and is often protective, we examined the changes in transcription of VEGF and its receptors after 4 h of hypoxia preconditioning. VEGF and its receptors Flt-1 and Flk-1 are up-regulated after hypoxia preconditioning. However, the transcription and translation of VEGF were paradoxically increased by siHIF-1alpha, suggesting that VEGF expression in stromal cells is not down-stream of HIF-1alpha.<br />Conclusions: These findings demonstrate that hypoxia preconditioning protection in corneal stromal cells requires HIF-1alpha, but that VEGF is not a component of the protection.
- Subjects :
- Animals
Apoptosis
Cadmium Chloride pharmacology
Cattle
Cells, Cultured
Corneal Stroma metabolism
Gene Expression Regulation drug effects
Gene Knockdown Techniques
Hypoxia-Inducible Factor 1, alpha Subunit antagonists & inhibitors
Hypoxia-Inducible Factor 1, alpha Subunit genetics
In Situ Nick-End Labeling
RNA Interference
RNA, Small Interfering
Stress, Physiological
Ultraviolet Rays
Cell Hypoxia
Corneal Stroma cytology
Hypoxia-Inducible Factor 1, alpha Subunit metabolism
Vascular Endothelial Growth Factor A metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1090-0535
- Volume :
- 15
- Database :
- MEDLINE
- Journal :
- Molecular vision
- Publication Type :
- Academic Journal
- Accession number :
- 19461932