FIG. 7.
Specific activation of the COL2C2 enhancer by SOX9. (A) The luciferase reporter plasmid contained an octamerized COL2C2 fragment placed upstream of the δ1-crystallin minimal promoter. (B) Regulation of the COL2C2 enhancer by various SOX protein derivatives. 10T1/2 cells were transfected with the luciferase reporter plasmid and various amounts of SOX expression plasmid (0, 1, 5, and 10 ng). Luciferase activity generated by the reporter in the absence of exogenous SOX was taken as 1. (C) The luciferase reporter plasmid containing either COL2C2 WT or COL2C2 M(SC) was cotransfected as for panel B. (D) Various amounts of effector vectors (0, 1, 5, and 10 ng) bearing genes encoding either SOX9 (a) or SOX9(1-264)-VP16 (Fig. 4A) (b) were cotransfected into 10T1/2 cells with luciferase reporter plasmids carrying COL2C2 WT (■), C2M(1-4) (•), or C2M(9-14) (▴). Luciferase activity generated by the reporter containing COL2C2 WT in the absence of exogenous SOX proteins was taken as 1. The VP16 activation domain could not overcome the requirement of the partner factor for SOX9 to activate the COL2C2 enhancer.