Effect of Egr-1 on HO-1 mRNA induction by ZnPP.

(A) Relative HO-1 mRNA induction by ZnPP in Egr-1^−/−mouse fibroblast cells. The HO-1 mRNA value for nontreated cell controls was assigned as 1. 3T3 indicates wild-type mouse fibroblast cells (NIH 3T3) incubated with 10 μM ZnPP for 24 hours. Egr^+/− indicates Egr-1 heterozygote mouse fibroblasts incubated with 10 μM ZnPP for 24 hours. Egr^−/−indicates Egr-1 homozygote null mutant mouse fibroblasts incubated with 10 μM ZnPP for 24 hours. (B) Effect of Egr-1 antisense oligonucleotides on ZnPP-induced HO-1 mRNA in HA-1 cells. Upper panel shows Egr-1 immunoreactive protein levels after incubation with Egr-1 antisense oligomer. Lower panel is the densitometric evaluation of HO-1 mRNA normalized to β-actin mRNA. Lane S, cells treated with 40 μM Egr-1 sense oligomers prior to incubation with ZnPP; lane A, cells treated with 40 μM Egr-1 antisense oligomers prior to incubation with ZnPP. Values represent the mean ± SE of 2 experiments; *P < .05 versus sense.