scholarly journals IκBα (inhibitory κBα) identified as labile repressor of MnSOD (manganese superoxide dismutase) expression

2004 ◽  
Vol 384 (3) ◽  
pp. 543-549 ◽  
Author(s):  
Kelley K. KININGHAM ◽  
Chotiros DAOSUKHO ◽  
Daret K. ST. CLAIR
Keyword(s):  
Superoxide Dismutase ◽  
Cell Line ◽  
Manganese Superoxide Dismutase ◽  
Phorbol Esters ◽  
De Novo ◽  
Nuclear Factor Κb ◽  
Binding Activity ◽  
Inhibitory Protein ◽  
Manganese Superoxide ◽  
Pre Treatment

Cytokines, phorbol esters, radiation and chemotherapeutic drugs up-regulate the expression of MnSOD (manganese superoxide dismutase). Using the VA-13 cell line, we studied the regulation of SOD2 upon treatment with PMA. Pre-treatment with CHX (cycloheximide) followed by PMA led to significantly higher levels of MnSOD mRNA compared with those with either agent alone, suggesting de novo synthesis of an inhibitory protein. PMA treatment modulates redox-sensitive transcription factors, therefore we evaluated the effects of this combination treatment upon AP-1 (activator protein 1) and NF-κB (nuclear factor κB), two trans-acting factors suggested to play a role in SOD2 regulation. Co-administration of CHX and PMA led to a time-dependent increase in the binding activity of NF-κB. Therefore we evaluated IκBα (inhibitory κBα) and found that co-administration decreased its steady-state level compared with either agent alone, suggesting that enhanced NF-κB activation is due to inhibition of IκBα synthesis. PMA activates PKC (protein kinase C) enzymes which phosphorylate IκBα, leading to its degradation, therefore we used GF109203X to inhibit PKC activity. Stable transfection utilizing a PMA-responsive element in the human SOD2 gene, showed a concentration-dependent decrease in luciferase and NF-κB-binding activity with GF109203X. Western blot analysis indicated the presence of several PKC isoforms in the VA-13 cell line; however, PMA pre-treatment specifically down-regulated α and βI, suggesting a role for one or more of these proteins in SOD2 induction. Taken together, these results indicate that the PKC pathway leading to SOD2 induction proceeds at least in part through NF-κB and that inhibition of IκBα synthesis might serve as a potential pharmacological approach to up-regulate MnSOD.

The effect of tumor necrosis factor-α on human malignant glial cells

1992 ◽  
Vol 76 (4) ◽  
pp. 652-659 ◽  
Author(s):  
Rolando F. Del Maestro ◽  
Monica Lopez-Torres ◽  
Warren B. McDonald ◽  
Eric C. Stroude ◽  
Indrasen S. Vaithilingam
Keyword(s):  
Superoxide Dismutase ◽  
Tumor Necrosis Factor ◽  
Cell Line ◽  
Tumor Necrosis ◽  
Manganese Superoxide Dismutase ◽  
Tumor Necrosis Factor Α ◽  
Superoxide Dismutase Activity ◽  
Manganese Superoxide ◽  
Factor Α ◽  
Necrosis Factor

✓ The influence of human recombinant tumor necrosis factor-α has been assessed on a cell line (U-251) derived from a human malignant glial tumor. The results of this study demonstrate that tumor necrosis factor-α at doses of 50 and 100 ng/ml: 1) did not have cytotoxic or cytostatic effects on the U-251 cell line; 2) significantly increased the intracellular activity of manganese superoxide dismutase but had no effect on copper and zinc superoxide dismutase, catalase, or glutathione peroxidase activity; and 3) did not significantly alter the intracellular or extracellular general protease and collagenase type IV activity of these cells. The resistance of the U-251 cell line to tumor necrosis factor-α cytotoxicity may be related in part to the high intrinsic manganese superoxide dismutase activity present in this cell line combined with the ability of this cell line to induce substantial amounts of protective manganese superoxide dismutase activity in response to tumor necrosis factor-α.

scholarly journals Tumor suppressive activity of a variant isoform of manganese superoxide dismutase released by a human liposarcoma cell line

2006 ◽  
Vol 119 (4) ◽  
pp. 932-943 ◽  
Author(s):  
Aldo Mancini ◽  
Antonella Borrelli ◽  
Antonella Schiattarella ◽  
Stefania Fasano ◽  
Antonella Occhiello ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Cell Line ◽  
Manganese Superoxide Dismutase ◽  
Suppressive Activity ◽  
Manganese Superoxide

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.

scholarly journals A role for manganese superoxide dismutase in radioprotection of hematopoietic stem cells by interleukin-1

Blood ◽  
1993 ◽  
Vol 81 (3) ◽  
pp. 639-646
Author(s):  
J Eastgate ◽  
J Moreb ◽  
HS Nick ◽  
K Suzuki ◽  
N Taniguchi ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Superoxide Dismutase ◽  
Antioxidant Enzyme ◽  
Cell Line ◽  
Manganese Superoxide Dismutase ◽  
Bone Marrow Cells ◽  
Interleukin 1 ◽  
Leukemic Cell ◽  
Manganese Superoxide ◽  
Marrow Cells

Pretreatment with interleukin-1 (IL-1) has been shown to protect mice from the myelotoxicity associated with irradiation via a mechanism potentially mediated through the induction of the antioxidant enzyme manganese superoxide dismutase (MnSOD). In this study, we have compared the ability of IL-1 to induce MnSOD mRNA in murine bone marrow cells and human cell lines with its ability to protect these cells against the damaging effects of ionizing radiation. Bone marrow cells obtained from mice 6 hours after a single injection of IL-1 demonstrate a dose- dependent increase in the expression of MnSOD RNA. In this same study, IL-1 was also shown to be radioprotective when given to mice 20 hours before lethal irradiation. Similarly, in vitro treatment with IL-1 of bone marrow cells isolated from 5-fluorouracil-treated mice results in elevated levels of MnSOD RNA. Pretreatment with IL-1 also protected bone marrow long-term culture-initiating cells capable of reconstituting irradiated stromal cultures from an irradiation insult. Furthermore, IL-1-treated human bone marrow cells display both elevated MnSOD RNA and protein levels when compared with media controls. The human A375 melanoma, A549 adenocarcinoma, and factor-dependent TF-1 leukemic cell lines demonstrate low basal MnSOD RNA levels that increase following treatment with IL-1. For the A375 cells, this correlates with increased MnSOD protein expression and radioprotection by IL-1 using a colony assay. In contrast, the chronic myelogenous leukemic cell line, K562, displays a high basal MnSOD RNA level, and this RNA expression is not further increased by IL-1 treatment. In addition, these cells are comparatively radioresistant and are not further protected by IL-1 treatment. Finally, the Mo-7 cell line displays a low basal level of MnSOD RNA that correlates with a high sensitivity to irradiation and IL-1 pretreatment has no effect on MnSOD RNA levels. Our results indicate that increased radioprotection by IL-1 correlates with the induction of the antioxidant enzyme MnSOD and this induction may be an important factor in IL-1 radioprotection.

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