Transcriptional activation of early‐response genes by hydrogen peroxide in a mouse osteoblastic cell line

Abstract

HzOZ, like other oxidants, is known to act as a mitogen at low concentrations in resting Balb/3T3 or mouse epidermal JB6 cells. We described previously that H 2 0 2 induces some early response genes in Balb/3T3 cells. We extended these observations using another cell line, MC3T3 (mouse osteoblastic) cells by examination of transcriptional activity of these genes and by using inhibitors of protein kinases. H2O2 increased the expressions of c-fos, c-jun, egr-1 and JE genes which are known to be early response genes and are induced by mitogenic stimuli in many types of cells. Exogenous addition of H z 0 2 increased the mRNA levels of these genes, the kinetics of increase being similar to those of their inductions by a phorbol ester or serum. Nuclear run-on transcription showed that this induction occurred at the transcriptional level. HzOz at 0.1 -0.2 mM induced maximal expressions of c-fus and c-jun, whereas 0.3 mM H z 0 2 was required for induction of stress-induced heme oxygenase mRNA. The inductions of c-fos and c-jun were inhibited by 50 pM H7, a protein kinase inhibitor that is relatively specific for protein kinase C, but were not affected by H9, relatively specific for CAMP-dependent protein kinase. In cells pretreated with 12-0-tetradecanoylphorbol 13-acetate, however, in which protein kinase was supposed to be downregulated, H2O2 induced c-fos and heme oxygenase as efficiently as in untreated cells. H z 0 2 did not increase the phosphorylation of p80 protein, which is known to be a substrate for protein kinase C. Thus, H z 0 2 seemed to induce c-fos and c-jun by activating protein kinases distinct from protein kinase C. Activity of the chloramphenicol acetyltransferase gene under control of the serum-response element of human c-jos genes was increased by HzOz treatment, whereas that under control of CAMP-response element was not affected. These results indicate that the inductions by H 2 0 2 of c-fos and possibly other early response genes are mediated through activation of the serum-response element in their enhancer.

Dithiocarbamates as potent inhibitors of nuclear factor kappa B activation in intact cells.

“…Recent reports showed that c-Jun mRNA is induced by low H202 concentrations in HeLa cells (72) and in an osteoblastic cell line (73). In HeLa cells, treatment with 250 /zM H202 for several hours could also elicit AP-1 binding activity.…”

Reversible Inactivation of the Tumor Suppressor PTEN by H2O2

“…Indeed, many normal cells exposed to H 2 O 2 exhibit increased proliferation and express growth-related genes (42)(43)(44). Furthermore, given that tumor cells produce large amounts of H 2 O 2 (45,46), this metabolite might also promote tumor cell proliferation.…”

The Activation of the Rat Copper/Zinc Superoxide Dismutase Gene by Hydrogen Peroxide through the Hydrogen Peroxide-responsive Element and by Paraquat and Heat Shock through the Same Heat Shock Element

“…From the sequence analysis of transcription factor binding sites in the PRE, the sequence of Elk1, which is the serum response factor accessory protein (25), was located between Ϫ533 and Ϫ520 of the SOD1 gene (24). Induction by H 2 O 2 of c-fos and possibly other early response genes was mediated through the activation of the serum response element for the binding site of serum response factor (26). The Ϫ533 to Ϫ520 sequence named as the HRE was tested for induction ability by H 2 O 2 .…”