FIG. 9.

HIF-1α regulates NOR-1 transcriptional activity through an HRE present in the NOR-1 promoter. (A) HUVEC were transfected with the luciferase reporter construct pGL3-NOR/-1703, and NOR-1 promoter activity was measured in cells cultured under normoxia (Norm) and in cells exposed to hypoxia (1% O₂) or CoCl₂ (1 mM) for 6 h. Data from three independent experiments performed in quadruplicate are shown. *, P < 0.05 versus cells exposed to normoxia. (B) NOR-1 promoter activity in cells transfected with the construct pGL-NOR/-1703 and cotransfected with the empty plasmid pcDNA3 or with a HIF-1α expression plasmid (pHIF-1α). *, P < 0.05 versus cells transfected with pcDNA3 (empty vector). (C) Schematic representation of the NOR-1 promoter (pGL-NOR/-1703) showing the putative HRE (white triangle; from −683 to −678) and three CRE sites (black triangles; from −83 to −42). The core consensus HRE binding site is indicated in bold, and changes in the HRE are boxed. (D) Hypoxia (black bars) increased NOR-1 promoter activity in cells transfected with the wild-type promoter construct but not in cells transfected with a construct with the putative HRE mutated (deleted white triangle) or with constructs (pNOR/-600 and pNOR/-300) that do not contain this element. Mutation of the three CRE sites in the construct pGL3-NOR/-1703 (deleted black triangles) did not prevent hypoxia-induced NOR-1 transcriptional activity. *, P < 0.05 versus cells transfected with the same construct and exposed to normoxia. Luc, luciferase.