17545484

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3

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.

eng

IM

MEDLINE

1040-0605

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NLM

L557-67

pubmed-meshheading:17545484-Amino Acids, Dicarboxylic, pubmed-meshheading:17545484-Animals, pubmed-meshheading:17545484-Chlorides, pubmed-meshheading:17545484-Cobalt, pubmed-meshheading:17545484-Deferoxamine, pubmed-meshheading:17545484-Dose-Response Relationship, Drug, pubmed-meshheading:17545484-Embryo, Mammalian, pubmed-meshheading:17545484-Epithelial Cells, pubmed-meshheading:17545484-Ferric Compounds, pubmed-meshheading:17545484-Hypoxia-Inducible Factor 1, pubmed-meshheading:17545484-Indoles, pubmed-meshheading:17545484-Lung, pubmed-meshheading:17545484-Mice, pubmed-meshheading:17545484-Morphogenesis, pubmed-meshheading:17545484-Neovascularization, Physiologic, pubmed-meshheading:17545484-Pyrroles, pubmed-meshheading:17545484-Signal Transduction, pubmed-meshheading:17545484-Vascular Endothelial Growth Factor Receptor-2

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

Journal Article, In Vitro, Research Support, Non-U.S. Gov't