The N-terminal domain of Sp2 can rescue target gene expression.

(A) The N-terminal domain of Sp2 has the capacity to activate transcription. The Gal4 DNA-binding domain (Gal4), and Gal4-Sp1NT and Gal4-Sp2NT fusions were transfected into HEK293 cells along with a 5xUAS-luciferase reporter construct. Fold activation by Gal4-Sp1NT and Gal4-Sp2NT is expressed relative to the Gal4 DNA-binding domain set to 1. (B, C) Relative expression of the Nlk (B), Grb2 and Oxr1 (C) genes in wt MEFs, Sp2ko MEFs and in Sp2ko MEFs re-expressing full-length Sp2 (Sp2FL) or the Sp2NT and Sp2ZF mutants. (C) Schematic representation of the exon-intron structures of the Grb2 and Oxr1 genes and the promoters bound by either Sp1/Sp3 or by Sp2. The primer pairs P1-P2 detect specifically transcripts derived from the Sp2-bound promoters. The primer pairs P3-P4 detect all transcripts. Transcript levels in wt MEFs determined by qPCR were set to 1. Gapdh mRNA levels were used for normalization. Data are presented as the average of three independent experiments +/-SD.