Increased Catalase mRNA Research Articles

SIRT3 overexpression and epigenetic silencing of catalase regulate ROS accumulation in CLL cells activating AXL signaling axis

Mitochondrial metabolism is the key source for abundant ROS in chronic lymphocytic leukemia (CLL) cells. Here, we detected significantly lower superoxide anion (O2−) levels with increased accumulation of hydrogen peroxide (H2O2) in CLL cells vs. normal B-cells. Further analysis indicated that mitochondrial superoxide dismutase (SOD)2, which converts O2− into H2O2 remained deacetylated in CLL cells due to SIRT3 overexpression resulting its constitutive activation. In addition, catalase expression was also reduced in CLL cells suggesting impairment of H2O2-conversion into water and O2 which may cause H2O2-accumulation. Importantly, we identified two CpG-islands in the catalase promoter and discovered that while the distal CpG-island (−3619 to −3765) remained methylated in both normal B-cells and CLL cells, variable degrees of methylation were discernible in the proximal CpG-island (−174 to −332) only in CLL cells. Finally, treatment of CLL cells with a demethylating agent increased catalase mRNA levels. Functionally, ROS accumulation in CLL cells activated the AXL survival axis while upregulated SIRT3, suggesting that CLL cells rapidly remove highly reactive O2− to avoid its cytotoxic effect but maintain increased H2O2-level to promote cell survival. Therefore, abrogation of aberrantly activated cell survival pathways using antioxidants can be an effective intervention in CLL therapy in combination with conventional agents.

Exercise Training Prevents Dexamethasone-induced Rarefaction.

Dexamethasone (DEX) causes rarefaction. In contrast, training (T) prevents rarefaction and stimulates angiogenesis. This study investigated the mechanisms responsible for the preventive role of T in DEX-induced rarefaction. Rats underwent T or were kept sedentary (8 weeks) and were treated with DEX or saline during the following 14 days. Tibialis anterior muscle was used for measurements of capillary density (CD), capillary-to-fiber ratio (C:F ratio), superoxide dismutase CuZn (SOD-1), superoxide dismutase MnSOD (SOD-2), catalase (CAT) mRNA as well as SOD-1, SOD-2, CAT, vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor-2 (VEGF-R2), cyclooxygenase-2 (COX-2), B-cell lymphoma 2 (Bcl-2), Bd-2-like protein 4 (Bax), p-Bax, and caspase-3 cleaved protein levels. DEX decreased CD (-38.1%), C:F ratio (-30.0%), VEGF (-19.0%), VEGFR-2 (-20.1%), COX-2 (-22.8%), Bcl-2 (-20.5%), Bcl-2/Bax ratio (-13.7%), p-Bax/Bax (-20.0%) and increased SOD-2 (+41.6%) and caspase-3 cleaved (+24.1%). Conversely, T prevented reductions in CD (+54.2%), C:F ratio (+32.9%), VEGF (+25.3%), VEGFR-2 (+22.2%), COX-2 (+31.5%), Bcl-2 (+35.5%), Bcl-2/Bax ratio (+19.9%), p-Bax/Bax (+32.1%), and caspase-3 cleaved increase (-7.8%). T increased CAT mRNA (+21.5%) in the DEX-treated group. In conclusion, T prevented the DEX-induced rarefaction by increasing antioxidant enzymes resulting in a better balance between apoptotic and anti-apoptotic protein levels.

Reduced glucose-induced insulin secretion in low-protein-fed rats is associated with altered pancreatic islets redox status.

In the present study, we investigated the relationship between early life protein malnutrition-induced redox imbalance, and reduced glucose-stimulated insulin secretion. After weaning, male Wistar rats were submitted to a normal-protein-diet (17%-protein, NP) or to a low-protein-diet (6%-protein, LP) for 60 days. Pancreatic islets were isolated and hydrogen peroxide (H2 O2 ), oxidized (GSSG) and reduced (GSH) glutathione content, CuZn-superoxide dismutase (SOD1), glutathione peroxidase (GPx1) and catalase (CAT) gene expression, as well as enzymatic antioxidant activities were quantified. Islets that were pre-incubated with H2 O2 and/or N-acetylcysteine, were subsequently incubated with glucose for insulin secretion measurement. Protein malnutrition increased CAT mRNA content by 100%. LP group SOD1 and CAT activities were 50% increased and reduced, respectively. H2 O2 production was more than 50% increased whereas GSH/GSSG ratio was near 60% lower in LP group. Insulin secretion was, in most conditions, approximately 50% lower in LP rat islets. When islets were pre-incubated with H2 O2 (100 μM), and incubated with glucose (33 mM), LP rats showed significant decrease of insulin secretion. This effect was attenuated when LP islets were exposed to N-acetylcysteine.

105 - Antioxidant Reprogram Macrophages from Pro-Tumor M2 to Anti-Tumor M1

Macrophages (Mφ) have high plasticity and can polarize to two extremes, pro-inflammatory M1 Mφ and immuno-suppressive M2 Mφ. In breast cancer, tumor associated Mφ (TAM) have a pro-tumor M2-like phenotype and are associated with decreased survival. Thus, it is vital to develop treatments to reprogram TAM away from pro-tumor M2 Mφ toward anti-tumor M1 Mφ. A recent study reported a lipid peroxide scavenger selectively inhibits M2 Mφ markers and cytokines. However, little is known about the differences in reactive oxygen species (ROS) metabolism between M1 Mφ and M2 Mφ. Our hypothesis is pro-tumorigenic M2 Mφ possess a distinct profile of pro- and anti-oxidant enzymes, as well as a different sensitivity to ROS modulation versus the anti-tumor M1 Mφ. Our results show M2 Mφ, derived from primary human monocytes, have a significant 20-30% reduction in intracellular ROS levels versus M1 Mφ by DCFH and DHE staining. Extracellular ROS synthesis was dramatically reduced by ~70% in M2 Mφ, in part due to reduced mRNA expression of Nox2 and its accessory protein CYBA in M2 Mφ. Another contributing factor to lower ROS levels is that M2 Mφ have significantly increased Cu/ZnSOD and Gpx1 protein and activity, as well as increased Catalase mRNA expression. These data suggest M2 Mφ have increased ROS metabolism versus M1 Mφ, which may provide an advantage in the oxidative tumor microenvironment. Furthermore, EcSOD re-expression in MB231, a triple negative breast cancer cell line, inhibited the MB231-mediated increase in M2 Mφ markers and decrease in M1 Mφ markers. We moved forward utilizing Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE), a small molecule SOD mimetic, shown to have anti-tumor effects. MnTE treatment increased M1 Mφ markers, IL-12b and CD86, while concurrently decreasing M2 Mφ markers, IL-10, CD163, and C206. MnTE also inhibited the ability of M2 Mφ to inhibit T cell activation suggesting ROS is required for M2 Mφ polarization and function. These studies provide rationale for antioxidant treatment of breast cancer to reprogram TAM from pro-tumorigenic M2-like TAM phenotype to a more tumoricidal M1-like phenotype.

Hibiscus sabdariffa L. aqueous extract attenuates hepatic steatosis through down-regulation of PPAR-γ and SREBP-1c in diet-induced obese mice

The growing incidence of obesity is a worldwide public health problem leading to a risk factor for non-alcoholic fatty liver disease, which extends from steatosis to steatohepatitis and cirrhosis. We investigated whether the aqueous extract of Hibiscus sabdariffa L. (Hs) reduces body weight gain and protects the liver by improving lipid metabolism in high fat diet-induced obese C57BL/6NHsd mice. We found that oral administration of the Hs extract reduced fat tissue accumulation, diminished body weight gain and normalized the glycemic index as well as reduced dyslipidemia compared to the obese mice group that did not receive Hs treatment. In addition, Hs treatment attenuated liver steatosis, down-regulated SREBP-1c and PPAR-γ, blocked the increase of IL-1, TNF-α mRNA and lipoperoxidation and increased catalase mRNA. Our results suggest that the anti-obesity, anti-lipidemic and hepatoprotective effects of the Hs extract are related to the regulation of PPAR-γ and SREBP-1c in the liver.

Differential activation of catalase expression and activity by PPAR agonists: Implications for astrocyte protection in anti-glioma therapy

Glioma survival is dismal, in part, due to an imbalance in antioxidant expression and activity. Peroxisome proliferator-activated receptor (PPAR) agonists have antineoplastic properties which present new redox-dependent targets for glioma anticancer therapies. Herein, we demonstrate that treatment of primary cultures of normal rat astrocytes with PPAR agonists increased the expression of catalase mRNA protein, and enzymatic activity. In contrast, these same agonists had no effect on catalase expression and activity in malignant rat glioma cells. The increase in steady-state catalase mRNA observed in normal rat astrocytes was due, in part, to de novo mRNA synthesis as opposed to increased catalase mRNA stability. Moreover, pioglitazone-mediated induction of catalase activity in normal rat astrocytes was completely blocked by transfection with a PPARγ-dominant negative plasmid. These data suggest that defects in PPAR-mediated signaling and gene expression may represent a block to normal catalase expression and induction in malignant glioma. The ability of PPAR agonists to differentially increase catalase expression and activity in normal astrocytes but not glioma cells suggests that these compounds might represent novel adjuvant therapeutic agents for the treatment of gliomas.

Cardioprotection from oxidative stress in the newborn heart by activation of PPARγ is mediated by catalase

Regulation of catalase (CAT) by peroxisome proliferator-activated receptor-γ (PPARγ) was investigated to determine if PPARγ activation provides cardioprotection from oxidative stress caused by hydrogen peroxide (H2O2) in an age-dependent manner. Left ventricular developed pressure (LVDP) was measured in Langendorff perfused newborn or adult rabbit hearts, exposed to 200μM H2O2, with perfusion of rosiglitazone (RGZ) or pioglitazone (PGZ), PPARγ agonists. We found: (1) H2O2 significantly decreased sarcomere shortening in newborn ventricular cells but not in adult cells. Lactate dehydrogenase (LDH) release occurred earlier in newborn than in adult heart, which may be due, in part, to the lower expression of CAT in newborn heart. (2) RGZ increased CAT mRNA and protein as well as activity in newborn but not in adult heart. GW9662 (PPARγ blocker) eliminated the increased CAT mRNA by RGZ. (3) In newborn heart, RGZ and PGZ treatment inhibited release of LDH in response to H2O2 compared to H2O2 alone. GW9662 decreased this inhibition. (4) LVDP was significantly higher in both RGZ+H2O2 and PGZ+H2O2 groups than in the H2O2 group. Block of PPARγ abolished this effect. In contrast, there was no effect of RGZ in adult. (5) The cardioprotective effects of RGZ were abolished by inhibition of CAT. In conclusion, PPARγ activation is cardioprotective to H2O2-induced stress in the newborn heart by upregulation of catalase. These data suggest that PPARγ activation may be an effective therapy for the young cardiac patient.

Effects of l-arginine and l-NAME supplementation on mRNA, protein expression and activity of catalase and glutathione peroxidase in brown adipose tissue of rats acclimated to different temperatures

Study elucidates molecular mechanisms underlying activation of catalase and glutathione peroxidase (GSH-Px) during cold-exposure by examining time-dependent changes in their mRNA, protein expression and activity, in interscapular brown adipose tissue (IBAT) of rats kept at room temperature (22±1 °C), or subjected to cold (4±1 °C) for 1, 3, 7, 12, 21 and 45 days. To examine involvement of nitric oxide ( •NO) in catalase and GSH-Px regulation, rats were treated with l-arginine or N ω-nitro- l-arginine-methyl ester ( l-NAME). In all groups, cold increased catalase mRNA, protein expression and activity from day 3 to day 45 of acclimation. However, cold-acclimation increased GSH-Px mRNA content on day 3, protein content from day 1 to day 45 and activity no sooner than on day 45. At room temperature, 21- and 45-day l-arginine and l-NAME supplementation increased catalase and GSH-Px mRNA expression, but decreased their activity. Concomitantly, catalase protein content decreased, while GSH-Px protein expression increased compared to control. Data show that cold is dominant stimulus that determines IBAT catalase and GSH-Px responses, by setting tissue metabolic state. In thermogenic-active tissue, catalase is regulated on transcriptional level, while GSH-Px is regulated post-translationally. On the other side, it was shown that •NO affects catalase and GSH-Px only in thermogenic-inactive tissue.

Hydroxytyrosol reduces intracellular reactive oxygen species levels in vascular endothelial cells by upregulating catalase expression through the AMPK–FOXO3a pathway

Reactive oxygen species are critically involved in the endothelial dysfunction that contributes to atherosclerosis development. Hydroxytyrosol (HT), a main phenolic compound in olive oil and leaves from Olea europaea L., has antiatherogenic properties with powerful antioxidant activity. The present study verifies the antioxidant activity of HT on H2O2-induced intracellular reactive oxygen species in porcine pulmonary artery endothelial cells (VECs) and the involved molecular mechanisms. Incubation of VECs with HT prevented the increase in intracellular reactive oxygen species levels in the presence of H2O2. HT increased catalase mRNA, protein and activity. Catalase siRNA suppressed HT-dependent reduction of intracellular reactive oxygen species. HT increased both cytosolic and nuclear protein levels of forkhead transcription factor 3a (FOXO3a), as well as the phosphorylation of AMP-activated protein kinase (AMPK) that translocates FOXO3a to the nucleus. AMPK siRNA and a specific inhibitor suppressed HT-induced FOXO3a upregulation and catalase expression. Moreover, FOXO3a siRNA blocked HT-dependent increase in catalase expression. Taken together, our findings strongly demonstrate that HT positively regulates the antioxidant defense system in VECs by inducing the phosphorylation of AMPK with subsequent activation of FOXO3a and catalase expression, and provides a molecular basis for the prevention of cardiovascular diseases by HT.

Effects of exposure to Prestige-like heavy fuel oil and to perfluorooctane sulfonate on conventional biomarkers and target gene transcription in the thicklip grey mullet Chelon labrosus

Thicklip grey mullets Chelon labrosus inhabit coastal and estuarine areas where they can be chronically exposed to commonly released pollutants such as polycyclic aromatic hydrocarbons (PAHs) and perfluorinated compounds. These pollutants can also originate from accidental spills, such as the Prestige oil spill in 2002, which resulted in the release of a heavy fuel oil that affected coastal ecosystems in the Bay of Biscay. Peroxisome proliferation (PP), induced biotransformation metabolism, immunosuppression and endocrine disruption are some of the possible biological effects caused by such chemicals. With the aim of studying the effects of organic toxic chemicals on such biological processes at the transcriptional and at the cell/tissue level, juvenile mullets were exposed to the typical mammalian peroxisome proliferator perfluorooctane sulfonate (PFOS), and to fresh (F) and weathered (WF) Prestige-like heavy fuel oil for 2 and 16 days. First, fragments of genes relevant to biotransformation, immune/inflammatory and endocrine disruption processes were cloned using degenerate primers. Fuel oil elicited a significant PP response as proved by the transcriptional upregulation of palmitoyl-CoA oxidase (aox1), peroxisome proliferator activated receptor α (pparα) and retinoic X receptor, by the AOX1 activity induction and by the increased peroxisomal volume density. PFOS only elicited a significant induction of AOX1 activity at day 2 and of PPARα mRNA expression at day 16. All treatments significantly increased catalase mRNA expression at day 16 in liver and at day 2 in gill. Cyp1a transcription (liver and gill) and EROD activity were induced in fuel oil treated organisms. In the case of phase II metabolism only hepatic glutathione S-transferase mRNA was overexpressed in mullets exposed to WF for 16 days. Functionally, this response was reflected in a significant accumulation of bile PAH metabolites. WF treated fish accumulated mainly high molecular weight metabolites while F exposure resulted in accumulation of mainly low molecular ones. Fuel oil significantly regulated immune response related complement component C3 and hepcidin transcription followed by a significant regulation of inflammatory response related apolipoprotein-A1 and fatty acid binding protein mRNAs at day 16. These responses were accompanied by a significant hepatic inflammatory response with lymphocyte accumulations (IRLA) and accumulation of melanomacrophage centers (MMC). PFOS did not elicit any transcriptional response in the studied biotransformation and immune related genes, although histologically significant effects were recorded in IRLA and MMC. A significant reduction of lysosomal membrane stability was observed in all exposed animals. No endocrine disruption effects were observed in liver while brain aromatase mRNA was overexpressed after all treatments at day 2 and estrogen receptor α was downregulated under WF exposure at day 16. These results show new molecular and cellular biomarkers of exposure to organic chemicals and demonstrate that in mullets PP could be regulated through molecular mechanisms similar to those in rodents, although the typical mammalian peroxisome proliferator PFOS and heavy fuel oil follow divergent mechanisms of action.

The Phytoestrogen Daidzein Affects the Antioxidant Enzyme System of Rat Hepatoma H4IIE Cells

Phytoestrogens such as the soy isoflavonoid daidzein have potential health benefits. The antioxidant properties of phytoestrogens are considered to be responsible in part for their protective effects. The antioxidant enzyme (AOE) system plays an important role in the defense of cells against oxidative insults. To determine whether flavonoids can exert antioxidative effects not only directly but also indirectly by modulating the AOE system, we investigated the influence of the flavonoid daidzein on the expression of different AOE. Daidzein treatment of hepatoma H4IIE cells increased catalase mRNA expression two- to threefold. Expression levels of copper zinc superoxide dismutase (CuZnSOD) were not affected by exposure to daidzein. Manganese superoxide dismutase (MnSOD) mRNA expression levels decreased slightly and glutathione peroxidase (GPx) levels increased slightly after daidzein exposure. Changes in AOE mRNA expression levels were significant at 300 micromol/L daidzein. To elucidate the mechanisms underlying the strong increase in catalase mRNA, transfection experiments were performed. Transient transfection of hepatoma cells with reporter plasmids containing different parts of the upstream region of the catalase gene showed a significant one- to threefold increase in reporter gene activity after daidzein exposure. This indicates that daidzein can directly activate the rat catalase promoter region. Despite the increase in catalase mRNA, daidzein pretreatment of cells did not protect against oxidative stress resulting from H(2)O(2) exposure. On the contrary, daidzein itself exerted a mild oxidative stress. In conclusion, the changes in the AOE system provoked by daidzein affected the oxidant rather than the antioxidant properties of daidzein.

Perinatal rat lung catalase gene expression: influence of corticosteroid and hyperoxia

Dexamethasone accelerates the late gestational rise in rat lung catalase activity; neonatal hyperoxia elevates rat lung catalase activity. We studied the regulation of catalase gene expression in these instances. Catalase mRNA/mg DNA increased to gestation day 22 and then fell to the concentration in adult lungs. The rate of transcription of catalase mRNA was higher on gestation day 22 than gestation day 19, whereas the half-life of catalase mRNA (approximately 7 h) was the same on both days. Dexamethasone given 48 and 24 h before expected birth (gestation 22 days) increased catalase mRNA concentration at days 20 and 22 without a change in catalase mRNA stability. Early postnatal hyperoxia (greater than 95% O2, 72 h) elevated catalase mRNA/mg DNA and doubled its half-life without changing its rate of transcription. We conclude the normal late gestational elevation of catalase activity and the increase of activity during prenatal dexamethasone treatment are regulated at the level of gene transcription. By contrast, the elevation of catalase activity during neonatal hyperoxia is mediated posttranscriptionally by increased catalase mRNA stability.