Figure 5. Identification of the minimal region in the promoter of Sost gene for HIF-1α activation.

(A) Schematic representation of the Sost deletion mutants. HRE: hypoxia response element. Sost-1 kb, Sost-540 bp, Sost-260 bp and Sost-106 bp Sost promoter reporter plasmids were constructed, using luciferase (LUC) as a reporter. (B) Deletion analysis of the Sost promoter-reporter constructs. Sost-1 kb, Sost-540 bp, Sost-260 bp and Sost-106 bp promoter-reporter plasmids (300 ng each) were cotransfected with 200 ng of the HIF-1α expression plasmid in HEK293 cells. Twenty-four hours post-transfection, cell extracts were prepared and analyzed for luciferase activity. Luciferase activity was normalized by β-galactosidase activity. Values are presented as the mean ±S.D.