Fig. 6.

CIITA represses COL1A1 promoter construct. A, COL1A1 promoter construct (−311, 0.5 μg) was co-transfected with green fluorescent protein (0.1 μg) and increasing amounts of CIITA constructs into FR cells. Luciferase activities were normalized by both protein concentration and green fluorescent protein fluorescence and expressed as a ratio compared with the empty vector control. Each experiment was repeated three times and values represented mean ± S.D. One-sample two-tailed t test was used to assess the statistical significance. At each dose tested, CIITA significantly repressed COL1A1 promoter activity (**, p < 0.01). B, all three components of the RFX5 complex with CIITA repress COL1A1 promoter activity better than CIITA alone. COL1A1 promoter construct (−311, 0.5 μg) was co-transfected with green fluorescent protein (0.1 μg) and RFX5, RFXB, or RFXAP constructs together with or without CIITA into IMR-90 cells. Luciferase activities were normalized by both protein concentration and GFP fluorescence and expressed as a ratio compared with the empty vector control. Each experiment was repeated three times and values represented mean ± S.D.