Figure 6

NFI-A represses mouse L1 gene expression. Results of luciferase-based reporter gene assays in N2A cells transfected with L1-11. The L1 reporter plasmid L1-11 contains 2943 bp upstream of exon 1 of the mouse L1 gene, exon 1, intron 1, exon 2 with the luciferase cDNA inserted to replace the L1 start codon by the luciferase start codon, intron 2 including the neural restrictive silencer element, exon 3, intron 3 and exon 4. beta Gal: coexpression of beta-galactosidase (negative control) (n = 98); NFI-A bs: coexpression of NFI-A bs (n = 91); NFI-A bs del: coexpression of NFI-A bs del (n = 35). For titration of beta Gal with NFI-A bs, the beta Gal expression plasmid was gradually replaced with the NFI-A bs expression plasmid at the ratios indicated below, leaving the total amount of transfected DNA constant. "1", bs:Gal = 1:59 (n = 28); "2", bs:Gal = 1:11 (n = 35); "3", bs:Gal = 1:5 (n = 49); "4", bs:Gal = 1:2 (n = 21); "5", bs:Gal = 1:1 (n = 49); "6", bs:Gal = 2:1 (n = 21). Data were acquired from 3 (bs:Gal = 1:2) to 9 (beta Gal, NFI-A bs) independent experiments. For normalization, luciferase activity was divided by the fluorescence of coexpressed EGFP. The relative luciferase activity of the beta Gal-transfected samples was set to 1. **, p < 0.01 vs. beta Gal; ***, p < 0.001 vs. beta Gal; ^§§§, p < 0.001 vs. NFI-A bs (two-tailed, unpaired t-test).