FIG. 1.

CIITA inhibits the collagen promoter in a dose-dependent manner. NIH 3T3 cells (1.1 × 10⁵) were plated in a 6-well dish 18 h before transfection. (A) Collagen α₂(I) CAT reporter gene (col-CAT) or an empty vector, pGL3-CAT, was transiently cotransfected with various amounts of CIITA or with an empty vector, pcDNA3. Cells were harvested 48 h later, and extracts were assayed for activity. A representative of three experiments is shown. The CAT activities were normalized based on the activity detected in the pGL3-CAT basic group. Error bars represent means ± standard errors. CIITA-NLS is the CIITA molecule with a simian virus 40 NLS at its C-terminal end. (B) The same cells were cotransfected with CIITA, col-CAT, and DRA-Luc reporter constructs. col-CAT monitors the effect of CIITA on the collagen promoter, and DRA-luc monitors the effect of CIITA on the DRA promoter. The panel on the left shows CAT activity, while the panel on the right shows luciferase activity. Experiments were repeated three times.