Heme Oxygenase-1 Expression In Cells Research Articles

Copper Nanoparticles Induce Oxidative Stress via the Heme Oxygenase 1 Signaling Pathway in vitro Studies.

PurposeThe toxicity of copper nanoparticle (CuNP) exposure in the ovaries has attracted attention recently, but the precise molecular mechanism involved requires further investigation. We investigated the cytotoxicity of CuNPs in ovarian granulosa cells and the protective effect of heme oxygenase 1 (HO-1) against CuNP-induced damage.MethodsHuman ovarian granulosa cells (COV434) were treated with CuNPs, and cytotoxicity was evaluated using Cell Counting Kit-8 and flow cytometry assays. Oxidative stress was identified using biochemical markers of oxidation and anti-oxidation. The protein levels of mitogen-activated protein kinase 14 (MAPK14), phospho-MAPK14, nuclear factor erythroid 2-related factor 2 (Nrf2), and HO-1 were measured by immunoblotting. Subsequently, for oxidative stress parameter detection, the cells were pre-treated with hemin to induce HO-1 expression prior to CuNP treatment.ResultsExposure to CuNPs decreased cell viability and the mitochondrial membrane potential, increased the apoptosis rate, and induced oxidative stress. Furthermore, hemin pretreatment induced HO-1 expression in cells, which partially reduced the accumulation of reactive oxygen species induced by CuNPs and increased the levels of antioxidant enzymes.ConclusionCuNPs exert cytotoxic effects on human ovarian granulosa cells by inducing oxidative stress, and may induce HO-1 expression via the MAPK14-Nrf2 signaling pathway. Moreover, HO-1 protects against oxidative stress induced by CuNPs.

Subversion of the Heme Oxygenase-1 Antiviral Activity by Zika Virus.

Heme oxygenase-1 (HO-1), a rate-limiting enzyme involved in the degradation of heme, is induced in response to a wide range of stress conditions. HO-1 exerts antiviral activity against a broad range of viruses, including the Hepatitis C virus, the human immunodeficiency virus, and the dengue virus by inhibiting viral growth. It has been reported that HO-1 displays antiviral activity against the Zika virus (ZIKV) but the mechanisms of viral inhibition remain largely unknown. Using a ZIKV RNA replicon with the Green Fluorescent Protein (GFP) as a reporter protein, we were able to show that HO-1 expression resulted in the inhibition of viral RNA replication. Conversely, we observed a decrease in HO-1 expression in cells replicating the ZIKV RNA replicon. The study of human cells infected with ZIKV showed that the HO-1 expression level was significantly lower once viral replication was established, thereby limiting the antiviral effect of HO-1. Our work highlights the capacity of ZIKV to thwart the anti-replicative activity of HO-1 in human cells. Therefore, the modulation of HO-1 as a novel therapeutic strategy against ZIKV infection may display limited effect.

A review on heme oxygenase-1 induction: is it a necessary evil.

Heme oxygenase-1 (HO-1) is considered to be the main protein in diseases arising as a result of oxidative and inflammatory insults. Tremendous research has been carried out on HO-1 since years, pertaining its cytoprotective effect against oxidative injury and other cellular stresses. HO-1, by regulating intracellular levels of pro-oxidant heme, or by other benefits of its by-products such as carbon monoxide (CO) and biliverdin (BV) had become an important candidate protein to be up-regulated to combat diverse stressful events. Although the beneficial effects of HO-1 induction have been reported in a number of cells and tissues, a growing body of evidence indicates that this increased HO-1 expression may lead to the progression of several diseases such as neurodegeneration, carcinogenesis. But it is not clear, what accounts for the increased expression of HO-1 in cells and tissues. The observed friendly role of HO-1 in a wide range of stress conditions since times is now doubtful. Therefore, more studies are needed to elucidate the exact role of HO-1 in various stressful events. Being more concise, elucidating the effect of HO-1 up-regulation on critical genes involved in particular diseases such as cancer will help to a larger extent to comprehend the exact role of HO-1. This review will assist in understanding the dual role (protective and detrimental) of HO-1 and the signaling pathway involved and will help in unraveling the doubtful role of HO-1 induction.

Morin exerts cytoprotective effects against oxidative stress in C2C12 myoblasts via the upregulation of Nrf2-dependent HO-1 expression and the activation of the ERK pathway

In the present study, we investigated the cytoprotective efficacy of morin, a natural flavonoid, against oxidative stress and elucidated the underlying mechanisms in C2C12 myoblasts. Our results indicated that morin treatment prior to hydrogen peroxide (H2O2) exposure significantly increased cell viability and prevented the generation of reactive oxygen species. H2O2-induced comet-like DNA formation and γH2AX phosphorylation were also markedly suppressed by morin with a parallel inhibition of apoptosis in C2C12 myoblasts, suggesting that morin prevented H2O2-induced cellular DNA damage. Furthermore, morin markedly enhanced the expression of heme oxygenase-1(HO-1) associated with the induction and phosphorylation of nuclear factor-erythroid2-related factor2(Nrf2) and the inhibition of Kelch-like ECH-associated protein1 (Keap1) expression. Notably, these events were eliminated by transient transfection with Nrf2‑specific small interfering RNA. Additional experiments demonstrated that the activation of the Nrf2/HO-1 pathway by morin was mediated by the extracellular signal‑regulated kinase(ERK) signaling cascade. This phenomenon was confirmed with suppressed Nrf2 phosphorylation and consequently diminished HO-1 expression in cells treated with a pharmacological inhibitor of ERK. Collectively, these results demonstrated that morin augments the cellular antioxidant defense capacity through the activation of Nrf2/HO‑1 signaling, which involves the activation of the ERK pathway, thereby protecting C2C12 myoblasts from H2O2-induced oxidative cytotoxicity.

Role of Nrf2/ARE signaling pathway in inhibition of LPS-induced inflammatory factor release from macrophages by hydrogen

Objective To evaluate the role of nuclear factor erythroid 2-related factor 2(Nrf2)/antioxidant response element(ARE)signaling pathway in inhibition of lipopolysaccharide(LPS)-induced inflammatory factor release from macrophages by hydrogen. Methods RAW264.7 macrophages of mice were cultured in 6-well plates(2×106 cells/well)and were divided into 4 groups(n=24 each)using a random number table: control group(group C); LPS group; hydrogen-rich saline+ LPS group(group LPS+ H2); Nrf2 small interference RNA(siRNA)+ LPS+ hydrogen-rich saline group(siRNA+ LPS+ H2 group). LPS 1 μg/ml was added in group LPS.In group LPS+ H2, LPS 1 μg/ml was added, and the culture medium was then replaced with the culture medium containing 0.6 mmol/L hydrogen-rich saline.In group siRNA+ LPS+ H2, after Nrf2-siRN was successfully transfected into the cells, the cells were continuously incubated for 24 h, and the culture medium was then replaced with the culture medium containing 0.6 mmol/L hydrogen-rich saline after LPS 1 μg/ml was added.At 24 h of incubation, the supernatant was separated for determination of the lactic dehydrogenase(LDH)activity(using colorimetric method)and for detection of the concentrations of tumor necrosis factor-alpha(TNF-α), interleukin-1 beta(IL-1β), high mobility group box-1(HMGB1)and IL-6(by ELISA). The cells were collected for measurement of the proliferation of cells(by methyl thiazolyl tetrazolium assay)and for determination of the expression of Nrf2 and heme oxygenase-1(HO-1)in cells(by Western blot). Results Compared with group C, the LDH activity and concentrations of TNF-α, IL-1β, IL-6 and HMGB1 in the supernatant were significantly increased, the proliferation of cells was significantly decreased, and the expression of HO-1 in cells was significantly up-regulated in LPS and siRNA+ LPS+ H2 groups, and the expression of Nrf2 in cells was significantly up-regulated in LPS and LPS+ H2 groups(P<0.05). Compared with group LPS, the LDH activity and concentrations of TNF-α, IL-1β, IL-6 and HMGB1 in the supernatant were significantly decreased, the proliferation of cells was significantly increased, and the expression of Nrf2 and HO-1 in cells was significantly up-regulated in group LPS+ H2, and the expression of Nrf2 and HO-1 in cells was significantly down-regulated in group siRNA+ LPS+ H2(P<0.05). Compared with group LPS+ H2, the LDH activity and concentrations of TNF-α, IL-1β, IL-6 and HMGB1 in the supernatant were significantly increased, the proliferation of cells was significantly decreased, and the expression of Nrf2 and HO-1 in cells was significantly down-regulated in group LPS+ H2+ siRNA(P<0.05). Conclusion The mechanism by which hydrogen inhibits LPS-induced inflammatory factor release from macrophages is related to the activation of Nrf2/ARE signaling pathway in mice. Key words: Nuclear factor-E2 related factor 2; Response elements; Signal transduction; Hydrogen; Lipopolysaccharides; Macrophages; Cytokines

Zinc Protoporphyrin Upregulates Heme Oxygenase-1 in PC-3 Cells via the Stress Response Pathway

Zinc protoporphyrin IX (ZnPP), a naturally occurring molecule formed in iron deficiency or lead poisoning, is a potent competitive inhibitor of heme oxygenase-1 (HO-1). It also regulates expression of HO-1 at the transcriptional level. However, the effect of ZnPP on HO-1 expression is controversial. It was shown to induce HO-1 expression in some cells, but suppress it in others. The objective of this study is to investigate the effect of ZnPP on HO-1 expression in prostate cancer PC-3 cells. Incubation of PC-3 cells with 10 μM ZnPP for 4 h showed only a slight induction of HO-1 mRNA and protein, but the induction was high after 16 h and was maintained through 48 h of incubation. Of all the known responsive elements in the HO-1 promoter, ZnPP activated mainly the stress response elements. Of the various protein kinase inhibitors and antioxidant tested, only Ro 31-8220 abrogated ZnPP-induced HO-1 expression, suggesting that activation of HO-1 gene by ZnPP may involve protein kinase C (PKC). The involvement of PKC α, β, δ, η, θ, and ζ isoforms was ruled out by the use of specific inhibitors. The isoform of PKC involved and participation of other transcription factors remain to be studied.