Fig 5. Effect of polyamines on luciferase activity from normal and modified Klf4-luc2 reporter plasmids in NIH3T3 cells.

(A) Schematic illustration of mouse Klf4 (E1-E3) and various Klf4-luc2 reporter plasmids are shown. Nucleotide sequences for exons and introns are represented as uppercase and lowercase, respectively. The two initiation codons (ATG) on Klf4 are underlined as 1^st and 2^nd. The dotted line on Klf4-luc2 reporter plasmids means that the region was deleted from WT plasmid. The site of mutated initiation codon, by site-directed mutagenesis, is indicated by an arrowhead (A→G). The green box in the plasmid illustration means the case of translation from 1^st initiation codon on E1. The yellow box shows luc2 ORF. (B) and (C); NIH3T3 cells co-transfected with the reporter plasmids and pGL4.75[hRluc/CMV] in the absence or presence of 5 mM DFMO, respectively. The graph on the left shows relative luciferase activities measured as the ratio of firefly and Renilla luciferase activity. The graph on the right shows data calculated as the ratio of relative luciferase activity of DFMO (+/−). The values of vector are shown as 1. Mean ± s.d. is shown, n = 3 replicates. **p < 0.01 compared with vector. n.d., not determined.