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Deprecated: Implicit conversion from float 213.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534 Am+J+Physiol+Lung+Cell+Mol+Physiol 2007 ; 293 (3): L557-67 Nephropedia Template TP
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Effect of chemical stabilizers of hypoxia-inducible factors on early lung development #MMPMID17545484
Groenman FA; Rutter M; Wang J; Caniggia I; Tibboel D; Post M
Am J Physiol Lung Cell Mol Physiol 2007[Sep]; 293 (3): L557-67 PMID17545484show ga
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.
Am+J+Physiol+Lung+Cell+Mol+Physiol 2007 ; 293 (3): L557-67
