Isolation and characterization of the hypoxia-inducible factor 1β in Drosophila melanogaster

The hypoxia-inducible factor 1 (HIF-1), a heterodimer composed of alpha and beta subunits, plays an important role in the cellular response to O(2) deprivation. In this paper, Drosophila HIF-1beta (dHIF-1beta) homolog is cloned and characterized. Further, Northern analyses showed that dHIF-1alpha and dHIF-1beta expressed their highest level at an embryonic stage. From the pupal stage on, their expression was sharply reduced and maintained at a steady level. Anoxia treatment up-regulated the expression of the both alpha and beta subunits. Over-expression of dHIF-1alpha in transgenic embryos resulted in embryonic lethality, while over-expression of dHIF-1beta significantly prolonged fly recovery time from a 5-min anoxic stupor. The cloning and characterization dHIF-1beta reported in this paper provide a framework for further genetic dissection of the HIF-1 complex in its role in the cellular or tissue response to O(2) deprivation.