Effect of chemical stabilizers of hypoxia-inducible factors on early lung development.

Abstract

Low oxygen stimulates pulmonary vascular development and airway branching and involves hypoxia-inducible factor (HIF). HIF is stable and initiates expression of angiogenic factors under hypoxia, whereas normoxia triggers hydroxylation of the HIF-1alpha subunit by prolyl hydroxylases (PHDs) and subsequent degradation. Herein, we investigated whether chemical stabilization of HIF-1alpha under normoxic (20% O(2)) conditions would stimulate vascular growth and branching morphogenesis in early lung explants. Tie2-LacZ (endothelial LacZ marker) mice were used for visualization of the vasculature. Embryonic day 11.5 (E11.5) lung buds were dissected and cultured in 20% O(2) in the absence or presence of cobalt chloride (CoCl(2), a hypoxia mimetic), dimethyloxalylglycine (DMOG; a nonspecific inhibitor of PHDs), or desferrioxamine (DFO; an iron chelator). Vascularization was assessed by X-gal staining, and terminal buds were counted. The fine vascular network surrounding the developing lung buds seen in control explants disappeared in CoCl(2)- and DFO-treated explants. Also, epithelial branching was reduced in the explants treated with CoCl(2) and DFO. In contrast, DMOG inhibited branching but stimulated vascularization. Both DFO and DMOG increased nuclear HIF-1alpha protein levels, whereas CoCl(2) had no effect. Since HIF-1alpha induces VEGF expression, the effect of SU-5416, a potent VEGF receptor (VEGFR) blocker, on early lung development was also investigated. Inhibition of VEGFR2 signaling in explants maintained under hypoxic (2% O(2)) conditions completely abolished vascularization and slightly decreased epithelial branching. Taken together, the data suggest that DMOG stabilization of HIF-1alpha during early development leads to a hypervascular lung and that airway branching proceeds without the vasculature, albeit at a slower rate.

• Authors: Freek A Groenman, Martin Rutter, Jinxia Wang, Isabella Caniggia, Dick Tibboel, Martin Post
• Journal: American journal of physiology. Lung cellular and molecular physiology (Am J Physiol Lung Cell Mol Physiol) Vol. 293 Issue 3 Pg. L557-67 (Sep 2007) ISSN: 1040-0605 [Print] United States
• PMID: 17545484 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Amino Acids, Dicarboxylic
• Chlorides
• Ferric Compounds
• Hypoxia-Inducible Factor 1
• Indoles
• Pyrroles
• Cobalt
• Semaxinib
• Vascular Endothelial Growth Factor Receptor-2
• cobaltous chloride
• Deferoxamine
• ferric chloride
• oxalylglycine

Topics

• Amino Acids, Dicarboxylic (pharmacology)
• Animals
• Chlorides
• Cobalt (pharmacology)
• Deferoxamine (pharmacology)
• Dose-Response Relationship, Drug
• Embryo, Mammalian (cytology, drug effects)
• Epithelial Cells (cytology)
• Ferric Compounds (pharmacology)
• Hypoxia-Inducible Factor 1 (metabolism)
• In Vitro Techniques
• Indoles (pharmacology)
• Lung (drug effects, embryology)
• Mice
• Morphogenesis (drug effects)
• Neovascularization, Physiologic (drug effects)
• Pyrroles (pharmacology)
• Signal Transduction (drug effects)
• Vascular Endothelial Growth Factor Receptor-2 (antagonists & inhibitors)