NF-κB and Sp1 response elements are essential for the basal level transcription of Neph3 in A293 cells. (A) A schematic representation of the Sp1 and NF-κB binding sites in the Neph3 promoter. (B) Nucleotide sequence of the human Neph3 promoter from -105 bp to TSS. The putative binding sites for NF-κB and Sp1 are boxed and core binding site is marked with Caps. The transcription start site is marked with +1. (C) Mutational analysis of the Sp1 and NF-κB binding sites in the Neph3 promoter. The Neph3 5' -Luc plasmids with mutated Sp1 and NF-κB binding sites were transfected into A293 cells and luciferase (LUC) activities were measured 24 h after transfection. The activities produced by the studied constructs were normalized against co-transfected control plasmid (phRL-TK) activities. The luciferase activities produced by the mutant constructs were compared with the activity produced by the unmutated construct. The values are presented as percentages of unmutated construct, which was set at 100% The values represent means +S.D. from three independent experiments performed in triplicate. Statistical difference of the promoter activity, using independent samples t-test, is shown against unmutated construct transfection. *** p < 0.001.