Figure 6.

Effects of changes in COUP-TF expression on opsin expression. A–C, Transient reporter assays were performed using Y79 (A, C) and COS7 (B) cells. The cells were transiently transfected with plasmids as indicated in the figure and cultured for 24 h (COS7) or 48 h (Y79). Luciferase activity was then examined. The luciferase reporters were S-opsin--luc for A and B and rhodopsin– luc for C. The arrows and arrowheads in B are discussed in Results. D–F, Y79 cells were transiently transfected with the indicated plasmids, and, after 48 h of culture, total RNA was extracted and used for cDNA synthesis. In F, Y79 cells transfected with the indicated plasmid along with an EGFP expression plasmid were purified by cell sorting based on EGFP expression, and total RNA was extracted for cDNA synthesis. Semiquantitative (top) and quantitative (bottom) PCR was done using primers for S-opsin, COUP-TFI (COUPI), COUP-TFII (COUPII), and G3PDH. G, Y79 cells were transfected with a control vector or BMP4 expression plasmid and cultured for 48 h. The cells were then harvested, and the expression of L-opsin, M-opsin, COUP-TFI, and G3PDH was examined by semiquantitative (top) and quantitative (bottom) RT-PCR. The results of quantitative PCR were shown by the relative expression level of each gene normalized to G3PDH. COUPI, COUP-TFI; COUPII, COUP-TFII.