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CO/HO-1 Induces NQO-1 Expression via Nrf2 Activation.

Kim HJ, Zheng M, Kim SK, Cho JJ, Shin CH, Joe Y, Chung HT - Immune Netw (2011)

Bottom Line: Exposure of HepG2 cells to CO resulted in significant induction of NQO1 in dose- and time-dependent manners.Analysis of the NQO1 promoter indicated that an antioxidant responsible element (ARE)-containing region was critical for the CO-induced Nrf2-dependent increase of NQO1 gene expression in HepG2 cells.Our results suggest that CO-induced Nrf2 increases the expression of NQO1 which is well known to detoxify reactive metabolites and ROS.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Ulsan, Ulsan 680-749, Korea.

ABSTRACT

Background: Carbon monoxide (CO) is a cytoprotective and homeostatic molecule with important signaling capabilities in physiological and pathophysiological situations. CO protects cells/tissues from damage by free radicals or oxidative stress. NAD(P)H:quinone oxidoreductase (NQO1) is a highly inducible enzyme that is regulated by the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway, which is central to efficient detoxification of reactive metabolites and reactive oxygen species (ROS).

Methods: We generated NQO1 promoter construct. HepG2 cells were treated with CO Releasing Molecules-2 (CORM-2) or CO gas and the gene expressions were measured by RT-PCR, immunoblot, and luciferase assays.

Results: CO induced expression of NQO1 in human hepatocarcinoma cell lines by activation of Nrf2. Exposure of HepG2 cells to CO resulted in significant induction of NQO1 in dose- and time-dependent manners. Analysis of the NQO1 promoter indicated that an antioxidant responsible element (ARE)-containing region was critical for the CO-induced Nrf2-dependent increase of NQO1 gene expression in HepG2 cells.

Conclusion: Our results suggest that CO-induced Nrf2 increases the expression of NQO1 which is well known to detoxify reactive metabolites and ROS.

No MeSH data available.


Related in: MedlinePlus

Effects of exogenous CO on the NQO1 and HO-1 protein induction. HepG2 cells were treated with various concentrations of CORM-2 as exogenous CO donor for 6 h and the cell lysates were used for immunoblot with antibody against NQO1, HO-1, and β-actin.
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Figure 3: Effects of exogenous CO on the NQO1 and HO-1 protein induction. HepG2 cells were treated with various concentrations of CORM-2 as exogenous CO donor for 6 h and the cell lysates were used for immunoblot with antibody against NQO1, HO-1, and β-actin.

Mentions: CO, a reaction product of HO-1 activity, has been shown to have potent anti-inflammatory, anti-proliferative, and anti-apoptotic effects. In our previous study, we revealed that CO induces Nrf2 activation and HO-1 expression in the liver cells (22). Furthermore, activated Nrf2 might induce various proteins which play a role of cytoprotection. Because NQO1 as one of the most cytoprotective molecules which is induced by Nrf2 in various stress conditions, we examined whether CO could increase NQO1 gene expression. As shown in Fig. 1A, NQO1 expression was increased by CO in a dose-dependent manner up to 50 µM of CORM-2. To confirm the effect of metal carrier of CORM-2, cells were treated with RuCl2 in a dose dependent manner. However, treatment of cells with equivalent molar concentrations of ruthenium chloride (RuCl2) did not induce NQO1 expression (Fig. 1B). As shown in Fig. 2A, we also found that NQO1 expression was increased in a time-dependent manner. Compared with un-stimulated cells, an increase in NQO1 expression was observed in cells exposed to CO for 6 h. We also found that NQO1 was induced by CO gas at 6 h (Fig. 2B). NQO1 protein expression, as well as NQO1 mRNA expression, was also increased by CORM-2 in a dose dependent manner (Fig. 3). We report for the first time that exogenous CO induces NQO1 expression in HepG2 cells.


CO/HO-1 Induces NQO-1 Expression via Nrf2 Activation.

Kim HJ, Zheng M, Kim SK, Cho JJ, Shin CH, Joe Y, Chung HT - Immune Netw (2011)

Effects of exogenous CO on the NQO1 and HO-1 protein induction. HepG2 cells were treated with various concentrations of CORM-2 as exogenous CO donor for 6 h and the cell lysates were used for immunoblot with antibody against NQO1, HO-1, and β-actin.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3275707&req=5

Figure 3: Effects of exogenous CO on the NQO1 and HO-1 protein induction. HepG2 cells were treated with various concentrations of CORM-2 as exogenous CO donor for 6 h and the cell lysates were used for immunoblot with antibody against NQO1, HO-1, and β-actin.
Mentions: CO, a reaction product of HO-1 activity, has been shown to have potent anti-inflammatory, anti-proliferative, and anti-apoptotic effects. In our previous study, we revealed that CO induces Nrf2 activation and HO-1 expression in the liver cells (22). Furthermore, activated Nrf2 might induce various proteins which play a role of cytoprotection. Because NQO1 as one of the most cytoprotective molecules which is induced by Nrf2 in various stress conditions, we examined whether CO could increase NQO1 gene expression. As shown in Fig. 1A, NQO1 expression was increased by CO in a dose-dependent manner up to 50 µM of CORM-2. To confirm the effect of metal carrier of CORM-2, cells were treated with RuCl2 in a dose dependent manner. However, treatment of cells with equivalent molar concentrations of ruthenium chloride (RuCl2) did not induce NQO1 expression (Fig. 1B). As shown in Fig. 2A, we also found that NQO1 expression was increased in a time-dependent manner. Compared with un-stimulated cells, an increase in NQO1 expression was observed in cells exposed to CO for 6 h. We also found that NQO1 was induced by CO gas at 6 h (Fig. 2B). NQO1 protein expression, as well as NQO1 mRNA expression, was also increased by CORM-2 in a dose dependent manner (Fig. 3). We report for the first time that exogenous CO induces NQO1 expression in HepG2 cells.

Bottom Line: Exposure of HepG2 cells to CO resulted in significant induction of NQO1 in dose- and time-dependent manners.Analysis of the NQO1 promoter indicated that an antioxidant responsible element (ARE)-containing region was critical for the CO-induced Nrf2-dependent increase of NQO1 gene expression in HepG2 cells.Our results suggest that CO-induced Nrf2 increases the expression of NQO1 which is well known to detoxify reactive metabolites and ROS.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Ulsan, Ulsan 680-749, Korea.

ABSTRACT

Background: Carbon monoxide (CO) is a cytoprotective and homeostatic molecule with important signaling capabilities in physiological and pathophysiological situations. CO protects cells/tissues from damage by free radicals or oxidative stress. NAD(P)H:quinone oxidoreductase (NQO1) is a highly inducible enzyme that is regulated by the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway, which is central to efficient detoxification of reactive metabolites and reactive oxygen species (ROS).

Methods: We generated NQO1 promoter construct. HepG2 cells were treated with CO Releasing Molecules-2 (CORM-2) or CO gas and the gene expressions were measured by RT-PCR, immunoblot, and luciferase assays.

Results: CO induced expression of NQO1 in human hepatocarcinoma cell lines by activation of Nrf2. Exposure of HepG2 cells to CO resulted in significant induction of NQO1 in dose- and time-dependent manners. Analysis of the NQO1 promoter indicated that an antioxidant responsible element (ARE)-containing region was critical for the CO-induced Nrf2-dependent increase of NQO1 gene expression in HepG2 cells.

Conclusion: Our results suggest that CO-induced Nrf2 increases the expression of NQO1 which is well known to detoxify reactive metabolites and ROS.

No MeSH data available.


Related in: MedlinePlus