Identification of the Osx binding site in the promoter of MMP13 gene.

(A) Deletion analysis of the MMP13 promoter-reporter constructs. MMP13-1 kb, MMP13-540 bp, MMP13-210 bp and MMP13-80 bp promoter-reporter plasmids (300 ng each) were cotransfected with 400 ng of the Osx expression plasmid in HEK293 cells. Twenty-four hours post-transfection, cell extracts were prepared and analyzed for luciferase activity and normalized to β-galactosidase activity. (B) The GC-rich element in MMP13-80 is responsible for MMP13 promoter reporter activation by Osx. The promoter mutant MMP13-80-M was transfected into HEK293 cells and analyzed as described in panel A. Luciferase activity was normalized by β-galactosidase activity.