Abstract 373: Manganese Superoxide Dismutase: A Novel Mediator of Heart Failure Development and Progression

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Sumitra Miriyala ◽  
Mini Chandra ◽  
Jonathan Fox ◽  
Christopher Kevil ◽  
Wayne Orr ◽  
...  
Keyword(s):  
Manganese Superoxide Dismutase ◽  
Primary Source ◽  
Early Mortality ◽  
Oxygen Species ◽  
Mitochondrial Reactive Oxygen Species ◽  
Wild Type ◽  
Constitutive Activation ◽  
Manganese Superoxide ◽  
Rate Of Oxygen Consumption ◽  
In Cells

Constitutive activation mitochondrial reactive oxygen species (ROS) has been implicated in both the pathogenesis and the progression of cardiovascular disease. Absence of SOD2 (gene that encodes MnSOD) is found to be embryonic lethal in animal models due to impairment of mitochondrial function, most noticeably in the heart. In our earlier investigation, we have shown that the MnSOD mimetic, distributes 3-fold more in mitochondria than in cytosol. The exceptional ability of MnSOD mimetic to dismute O 2 •- parallels its ability to reduce ONOO– and CO3–. Based on our earlier reports, we have generated mice that specifically lack MnSOD in cardiomyocytes (Mhy6-SOD2 Δ ). These mice showed early mortality ~4 months due to cardiac mitochondrial dysfunction. Oxidative phosphorylation (OXPHOS) in mitochondria is the predominant mode for O 2 consumption in cells, and the mitochondria are the primary source of ROS in cells due to leaked electrons. FACS analyses using Mito-Tracker Green indicated that the mass of mitochondria per cell was slightly decreased in the Mhy6-SOD2 Δ to the wild type. The rate of oxygen consumption per cells was significantly lower in Mhy6-SOD2 Δ cardiomyocytes than that in wild type. The most noticeable difference in the O 2 consumption was found in the presence of FCCP (H+ ionophore / uncoupler). Remarkably, while the FCCP treatment increased O 2 consumption in wild type, the treatment showed no effect on the O 2 consumption in the Mhy6-SOD2 Δ cardiomyocytes. The result indicated that the low basal OXPHOS activity in Mhy6-SOD2 Δ was due to unusually low OXPHOS potential.

Abstract 357: Manganese Superoxide Dismutase: a Novel Mediator of Heart Failure Development and Progression

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Sumitra Miriyala ◽  
Mini Chandra ◽  
Benjamin Maxey ◽  
Daret K St. Clair ◽  
Manikandan Panchatcharam
Keyword(s):  
Superoxide Dismutase ◽  
Oxygen Consumption ◽  
Manganese Superoxide Dismutase ◽  
Consumption Rate ◽  
Primary Source ◽  
Wild Type ◽  
Membrane Pore ◽  
Manganese Superoxide ◽  
Rate Of Oxygen Consumption ◽  
In Cells

Manganese Superoxide Dismutase (MnSOD), an antioxidant enzyme that catalyzes the conversion of superoxide radicals (O 2 •-) in mitochondria. Constitutive activation mitochondrial reactive oxygen species (ROS) has been implicated in both the pathogenesis and the progression of cardiovascular disease. Absence of SOD2 (gene that encodes MnSOD) is found to be embryonic lethal in animal models due to impairment of mitochondrial function, most noticeably in the heart. In our earlier investigation, we have shown that the MnSOD mimetic, MnTnBuOE-2-PyP 5+ distributes 3-fold more in mitochondria than in cytosol. The exceptional ability of MnTnBuOE-2-PyP 5+ to dismute O 2 •- parallels its ability to reduce ONOO– and CO3–. Based on our earlier reports, we have generated mice that specifically lack MnSOD in cardiomyocytes (Mhy6-SOD2 Δ ). These mice showed early mortality ~4 months due to cardiac mitochondrial dysfunction. Oxidative phosphorylation (OXPHOS) in mitochondria is the predominant mode for O 2 consumption in cells, and the mitochondria are the primary source of ROS in cells due to leaked electrons. FACS analyses using Mito-Tracker Green indicated that the mass of mitochondria per cell was slightly decreased in the Mhy6-SOD2 Δ to the wild type. We then examined OXPHOS levels in Mhy6-SOD2 Δ v.s. wild type using a Seahorse XF analyzer. The rate of oxygen consumption per cells was signi[[Unable to Display Character: fi]]cantly lower in Mhy6-SOD2 Δ cardiomyocytes than that in wild type. The most noticeable difference in the O 2 consumption was found in the presence of FCCP (H+ ionophore / uncoupler). FCCP is an inner membrane pore opener which resets the proton gradient between the mitochondrial matrix and the interspace, resulting in continuous transport of protons and consuming O 2 at the maximum potential. Remarkably, while the FCCP treatment increased O 2 consumption in wild type, the treatment showed no effect on the O 2 consumption in the Mhy6-SOD2 Δ cardiomyocytes. The result indicated that the low basal OXPHOS activity in Mhy6-SOD2 Δ was due to unusually low OXPHOS potential. We examined glycolysis in these cells by measuring extracellular acidi[[Unable to Display Character: fi]]cation (ECAR) and the pattern exactly opposite to that of oxygen consumption rate (OCR) was observed for glycolysis rates between Mhy6-SOD2 Δ and wild type.

scholarly journals Late chronic catechin antioxidant treatment is deleterious to the endothelial function in aging mice with established atherosclerosis

2010 ◽  
Vol 298 (6) ◽  
pp. H2062-H2070 ◽  
Author(s):  
Marie-Ève Gendron ◽  
Jean-François Théorêt ◽  
Aida M. Mamarbachi ◽  
Annick Drouin ◽  
Albert Nguyen ◽  
...  
Keyword(s):  
Vascular Function ◽  
Manganese Superoxide Dismutase ◽  
Leukocyte Adhesion ◽  
Plaque Burden ◽  
Oxygen Species ◽  
Wild Type ◽  
Vascular Protection ◽  
Antioxidant Treatment ◽  
Age Related ◽  
Manganese Superoxide

Various antioxidants, including polyphenols, prevent the development of atherosclerosis in animal models, contrasting with the failure of antioxidants to provide benefits in patients with established atherosclerosis. We therefore tested in a mouse model the hypothesis that although catechin is atheroprotective in prevention, catechin brings no global vascular protection when initiated after established atherosclerosis, because aging associated with dyslipidemia has induced irreversible dysfunctions. To this end, LDLr−/−; hApoB+/+ atherosclerotic (ATX, 9 mo old) and pre-ATX (3 mo old) male mice were treated with catechin (30 mg·kg−1·day−1) up to 12 mo of age. Vascular function and endothelium/leukocyte interactions were studied at 12 mo old. The renal artery endothelium-dependent dilations were impaired with age whereas adhesion of leukocytes onto the native aortic endothelium was increased ( P < 0.05). Aortic oxidative stress [reactive oxygen species (ROS)] increased ( P < 0.05) at 3 mo in ATX and at 12 mo in wild-type mice. Aorta mRNA expression of NADPH oxidase increased, whereas that of manganese superoxide dismutase decreased in 12-mo-old ATX mice only. In mice with established ATX, catechin (from 9 to 12 mo) reduced ( P < 0.05) by ∼60% ROS without affecting plaque burden. Notably, catechin worsened endothelial dysfunction and further increased leukocyte adhesion ( P < 0.05) in ATX mice. In contrast, the same catechin treatment reversed all age-related dysfunctions in wild-type mice. On the other hand, in pre-ATX mice treated for 9 mo with catechin, plaque burden was reduced by 64% ( P < 0.05) and all vascular markers were normalized to the 3-mo-old values. These results demonstrate that an antioxidant treatment is deleterious in mice with established atherosclerosis.

scholarly journals Unique Cellular and Biochemical Features of Human Mitochondrial Peroxiredoxin 3 Establish the Molecular Basis for Its Specific Reaction with Thiostrepton

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 150
Author(s):  
Kimberly J. Nelson ◽  
Terri Messier ◽  
Stephanie Milczarek ◽  
Alexis Saaman ◽  
Stacie Beuschel ◽  
...  
Keyword(s):  
Oxygen Species ◽  
Mitochondrial Reactive Oxygen Species ◽  
Wild Type ◽  
Cellular Models ◽  
Chemotherapeutic Approach ◽  
Promising Target ◽  
Redox Responsive ◽  
Catalytic Cysteine ◽  
Increased Sensitivity ◽  
Peroxiredoxin 3

A central hallmark of tumorigenesis is metabolic alterations that increase mitochondrial reactive oxygen species (mROS). In response, cancer cells upregulate their antioxidant capacity and redox-responsive signaling pathways. A promising chemotherapeutic approach is to increase ROS to levels incompatible with tumor cell survival. Mitochondrial peroxiredoxin 3 (PRX3) plays a significant role in detoxifying hydrogen peroxide (H2O2). PRX3 is a molecular target of thiostrepton (TS), a natural product and FDA-approved antibiotic. TS inactivates PRX3 by covalently adducting its two catalytic cysteine residues and crosslinking the homodimer. Using cellular models of malignant mesothelioma, we show here that PRX3 expression and mROS levels in cells correlate with sensitivity to TS and that TS reacts selectively with PRX3 relative to other PRX isoforms. Using recombinant PRXs 1–5, we demonstrate that TS preferentially reacts with a reduced thiolate in the PRX3 dimer at mitochondrial pH. We also show that partially oxidized PRX3 fully dissociates to dimers, while partially oxidized PRX1 and PRX2 remain largely decameric. The ability of TS to react with engineered dimers of PRX1 and PRX2 at mitochondrial pH, but inefficiently with wild-type decameric protein at cytoplasmic pH, supports a novel mechanism of action and explains the specificity of TS for PRX3. Thus, the unique structure and propensity of PRX3 to form dimers contribute to its increased sensitivity to TS-mediated inactivation, making PRX3 a promising target for prooxidant cancer therapy.

scholarly journals Bladder function in mice with inducible smooth muscle-specific deletion of the manganese superoxide dismutase gene

2015 ◽  
Vol 309 (3) ◽  
pp. C169-C178 ◽  
Author(s):  
Guiming Liu ◽  
Rania A. Elrashidy ◽  
Nan Xiao ◽  
Michael Kavran ◽  
Yexiang Huang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Superoxide Dismutase ◽  
Smooth Muscle ◽  
Manganese Superoxide Dismutase ◽  
Bladder Function ◽  
Antioxidant Systems ◽  
Wild Type ◽  
Manganese Superoxide ◽  
Specific Deletion

Manganese superoxide dismutase (MnSOD) is considered a critical component of the antioxidant systems that protect against oxidative damage. We are interested in the role of oxidative stress in bladder detrusor smooth muscle (SM) in different disease states. In this study, we generated an inducible, SM-specific Sod2−/− mouse model to investigate the effects of MnSOD depletion on the function of the bladder. We crossbred floxed Sod2 ( Sod2lox/lox) mice with mice containing heterozygous knock-in of a gene encoding a tamoxifen-activated Cre recombinase in the SM22α promoter locus [SM-CreERT2(ki)Cre/+]. We obtained Sod2lox/lox,SM-CreERT2(ki)Cre/+ mice and injected 8-wk-old males with 4-hydroxytamoxifen to induce Cre-mediated excision of the floxed Sod2 allele. Twelve weeks later, SM-specific deletion of Sod2 and depletion of MnSOD were confirmed by polymerase chain reaction, immunoblotting, and immunohistochemistry. SM-specific Sod2−/− mice exhibited normal growth with no gross abnormalities. A significant increase in nitrotyrosine concentration was found in bladder SM tissue of SM-specific Sod2−/− mice compared with both wild-type mice and Sod2+/+, SM-CreERT2(ki)Cre/+ mice treated with 4-hydroxytamoxifen. Assessment of 24-h micturition in SM-specific Sod2−/− mice revealed significantly higher voiding frequency compared with both wild-type and SM-specific Cre controls. Conscious cystometry revealed significantly shorter intercontraction intervals and lower functional bladder capacity in SM-specific Sod2−/− mice compared with wild-type mice. This novel model can be used for exploring the mechanistic role of oxidative stress in organs rich in SM in different pathological conditions.

scholarly journals Accumulation of manganese superoxide dismutase under metal-depleted conditions: proposed role for zinc ions in cellular redox balance

2004 ◽  
Vol 377 (1) ◽  
pp. 241-248 ◽  
Author(s):  
Kaoru OTSU ◽  
Yoshitaka IKEDA ◽  
Junichi FUJII
Keyword(s):  
Oxidative Stress ◽  
Superoxide Dismutase ◽  
Dna Binding ◽  
Manganese Superoxide Dismutase ◽  
Binding Activity ◽  
Rat Liver Mitochondria ◽  
Zinc Ions ◽  
Dna Binding Activity ◽  
Manganese Superoxide ◽  
In Cells

A diet low in copper results in increased levels of MnSOD (manganese superoxide dismutase), a critical antioxidative enzyme conferring protection against oxidative stress, in rat liver mitochondria. The mechanism for this was investigated using cultured HepG2 cells, a human hepatocellular carcinoma-derived line. MnSOD activity increased 5–7-fold during incubation in a medium supplemented with metal-depleted fetal bovine serum, with a corresponding elevation of its mRNA levels. Metal depletion also decreased CuZnSOD and glutathione peroxidase levels to approx. 70–80% of baseline. When zinc ions were added to the medium at micromolar levels, MnSOD accumulation was suppressed; however, copper ions had essentially no effect on MnSOD expression. Since the intracellular redox status was shifted to a more oxidized state by metal depletion, we examined the DNA-binding activity of NF-κB (nuclear factor-κB), an oxidative stress-sensitive transactivating factor that plays a primary role in MnSOD induction. A gel shift assay indicated that the DNA-binding activity of NF-κB was increased in cells maintained in metal-depleted culture, suggesting the involvement of the transactivating function of NF-κB in this induction. This was further supported by the observation that curcumin suppressed both the DNA-binding activity of NF-κB and the induction of MnSOD mRNA in cells cultivated under metal-depleted conditions. These results suggest that the level of zinc, rather than copper, is a critical regulatory factor in MnSOD expression. It is possible that a deficiency of zinc in the low-copper diet may be primarily involved in MnSOD induction.

Sign in / Sign up

Export Citation Format

Share Document