| First Author | Helton R | Year | 2005 |
| Journal | J Neurosci | Volume | 25 |
| Issue | 16 | Pages | 4099-107 |
| PubMed ID | 15843612 | Mgi Jnum | J:98637 |
| Mgi Id | MGI:3579234 | Doi | 10.1523/JNEUROSCI.4555-04.2005 |
| Citation | Helton R, et al. (2005) Brain-specific knock-out of hypoxia-inducible factor-1alpha reduces rather than increases hypoxic-ischemic damage. J Neurosci 25(16):4099-107 |
| abstractText | Hypoxia-inducible factor-1alpha (HIF-1alpha) plays an essential role in cellular and systemic O(2) homeostasis by regulating the expression of genes important in glycolysis, erythropoiesis, angiogenesis, and catecholamine metabolism. It is also believed to be a key component of the cellular response to hypoxia and ischemia under pathophysiological conditions, such as stroke. To clarify the function of HIF-1alpha in the brain, we exposed adult mice with late-stage brain deletion of HIF-1alpha to hypoxic injuries. Contrary to expectations, the brains from the HIF-1alpha-deficient mice were protected from hypoxia-induced cell death. These surprising findings suggest that decreasing the level of HIF-1alpha can be neuroprotective. Gene chip expression analysis revealed that, contrary to expectations, the majority of hypoxia-dependent gene-expression changes were unaltered, whereas a specific downregulation of apoptotic genes was observed in the HIF-1alpha-deficient mice. Although the role of HIF-1alpha has been extensively characterized in vitro, in cancer models, and in chronic preconditioning paradigms, this is the first study to evaluate the role of HIF-1alpha in vivo in the brain in response to acute hypoxia/ischemia. Our data suggest, that in acute hypoxia, the neuroprotection found in the HIF-1alpha-deficient mice is mechanistically consistent with a predominant role of HIF-1alpha as proapoptotic and loss of function leads to neuroprotection. Furthermore, our data suggest that functional redundancy develops after excluding HIF-1alpha, leading to the preservation of gene expression regulating the majority of other previously characterized HIF-dependent genes. |
