FIGURE 5.

Sp1, GABP, and Elf-1 cooperatively activate the FcRγ promoter. a, expression plasmids of GABPα, GABPβ, Elf-1, and Sp1 (filled bars) or corresponding empty vectors as control (hatched bars) were introduced into KU812 cells with the reporter plasmid pGLγ-(-177/-1) carrying the FcRγ nt -177/-1 region upstream of a luciferase gene for a transient expression assay. b, KU812 cells were co-transfected with an expression plasmid of Sp1 and the reporter plasmid pGLγ-(-177/-1) with or without nucleotide substitutions at the GABP-binding site. c, siRNA expression plasmid of GABPα was co-introduced with the Sp1 expression plasmid and pGLγ-177/-1 in KU182 cells. a–c, relative luciferase (Luc) activities to that of pGLγ-(-177/-1) alone are shown. Results are represented as means ± S.D. of three independent experiments. d, expression of GABPα, GABPβ, Elf-1, and Sp1 in the cells transfected with indicated combinations of expression plasmids and empty vectors was detected by Western blotting. e, expression of GABPα in the cells transfected with GABPα siRNA was analyzed by Western blotting. Lane 1, no treatment; lane 2 and 3,GABPα siRNA; lane 4, control siRNA.