| First Author | Shomento SH | Year | 2010 |
| Journal | J Cell Biochem | Volume | 109 |
| Issue | 1 | Pages | 196-204 |
| PubMed ID | 19899108 | Mgi Jnum | J:161255 |
| Mgi Id | MGI:4457845 | Doi | 10.1002/jcb.22396 |
| Citation | Shomento SH, et al. (2010) Hypoxia-inducible factors 1alpha and 2alpha exert both distinct and overlapping functions in long bone development. J Cell Biochem 109(1):196-204 |
| abstractText | The hypoxia-inducible factors have recently been identified as critical regulators of angiogenic-osteogenic coupling. Mice overexpressing HIFalpha subunits in osteoblasts produce abundant VEGF and develop extremely dense, highly vascularized long bones. In this study, we investigated the individual contributions of Hif-1alpha and Hif-2alpha in angiogenesis and osteogenesis by individually disrupting each Hifalpha gene in osteoblasts using the Cre-loxP method. Mice lacking Hif-1alpha demonstrated markedly decreased trabecular bone volume, reduced bone formation rate, and altered cortical bone architecture. By contrast, mice lacking Hif-2alpha had only a modest decrease in trabecular bone volume. Interestingly, long bone blood vessel development measured by angiography was decreased by a similar degree in both DeltaHif-1alpha and DeltaHif-2alpha mice suggesting a common role for these Hifalpha subunits in skeletal angiogenesis. In agreement with this idea, osteoblasts lacking either Hif-1alpha or Hif-2alpha had profound reductions in VEGF mRNA expression but only the loss of Hif-1alpha impaired osteoblast proliferation. These findings indicate that expression of both Hif-1alpha and Hif-2alpha by osteoblasts is required for long bone development. We propose that both Hif-1alpha and Hif-2alpha function through cell non-autonomous modes to promote vascularization of bone and that Hif-1alpha also promotes bone formation by exerting direct actions on the osteoblast. |
