Resveratrol protects against hyperglycemia-induced oxidative damage to mitochondria by activating SIRT1 in rat mesangial cells

Oxidative stress and mitochondrial dysfunction are involved in the pathogenesis of diabetic nephropathy (DN). Resveratrol has potent protective effects on diabetes and diabetic complications including diabetic nephropathy. We aimed to investigate the protective effects of resveratrol on mitochondria and the underlying mechanisms by using an in vitro model of hyperglycemia. We exposed primary cultured rat mesangial cells to high glucose (30 mM) for 48 h. We found that pretreatment with resveratrol (10 μM) 6 h prior to high glucose treatment significantly reduced hyperglycemia-induced increase in reactive oxygen species (ROS) production and mitochondrial superoxide generation, as well as stimulated MnSOD activity. In addition, resveratrol pretreatment significantly reversed the decrease of mitochondrial complex III activity in glucose-treated mesangial cells, which is considered to be the major source of mitochondrial oxidative stress in glucose-treated cells. Furthermore, resveratrol pretreatment efficiently restored the hyperpolarization of ?Ψm, increased ATP production and preserved the mtDNA content. All of these protective effects of resveratrol were successfully blocked by siRNA targeting SIRT1 and EX-527, a specific inhibitor of SIRT1 activity. Our results indicated that resveratrol efficiently reduced oxidative stress and maintained mitochondrial function related with activating SIRT1 in glucose-treated mesangial cells. It suggested that resveratrol is pharmacologically promising for treating diabetic nephropathy.     

Evaluation of the potential protective effects of ad libitum black grape juice against liver oxidative damage in whole-body acute X-irradiated rats

Aims

The aim of this study was to evaluate the potential protective effects of ad libitum black grape (Vitis labrusca) juice against liver oxidative damage in whole-body acute X-irradiated rats.

Main methods

Animals were fed ad libitum and drank voluntarily black grape juice or placebo (isocaloric glucose and fructose solution) for 6 days before and 15 days following a 6 Gy X-irradiation from a 200 kV machine.

Key findings

Irradiated animals receiving placebo showed a significant increase in the concentration of thiobarbituric acid-reactive substances (TBARS), a marker of lipid peroxidation, as well as a significant decrease in both Cu/Zn superoxide dismutase (Cu/ZnSOD) and glutathione peroxidase (GPx) activity and reduced glutathione concentration (GSH). Black grape juice supplementation resulted in a reversal of lipid peroxidation, Cu/ZnSOD activity, and GSH concentration, towards values not significantly differing from those in non-irradiated, placebo-supplemented rats. Poly(ADP-ribose) polymerase (PARP-1) and Cu/ZnSOD changes in protein expression were observed for irradiated rats. No change in p53 expression or DNA fragmentation was found.

Significance

Ad libitum black grape juice intake is able to restore the liver primary antioxidant system against adverse effects due to whole-body acute X-irradiation in rats after 15 days post-irradiation. The results support using antioxidant supplements as a preventive tool against radiation-induced harm.     

MnSOD deficiency has a differential effect on disease progression in two different ALS mutant mouse models

Mitochondrial dysfunction and oxidative stress are thought to participate in the pathogenesis of amyotrophic lateral sclerosis (ALS). The purpose of this study was to determine the effect of reduced mitochondrial antioxidant defense on lifespan and disease progression in two mouse models of familial ALS (G93A and H46R/H48Q mutant lines) that represent pseudo-wildtype and metal-deficient ALS mutants, respectively. The metal-deficient H46R/H48Q mutant differs from the G93A mutant in that it cannot bind copper in the active site and thus lacks SOD activity. We crossed each of these mutant lines with mice deficient in the mitochondrial matrix antioxidant enzyme MnSOD (Sod2+/- mice). In both high (G93A1Gur) and low (G93ADL) copy G93A strains, MnSOD deficiency caused a decrease in lifespan that was associated with a reduced disease duration rather than earlier disease onset. In contrast, MnSOD deficiency had no effect on lifespan or disease parameters of H46R/H48Q mutant mice. MnSOD deficiency thus has a differential effect on disease progression in different mutant SOD1 ALS mouse models, suggesting that different ALS-causing mutations in SOD1 result in disease progression by at least proximally different mechanisms/pathways.     

D-4F, an apoA-I mimetic peptide, inhibits proliferation and tumorigenicity of epithelial ovarian cancer cells by upregulating the antioxidant enzyme MnSOD

We recently reported that apoA-I and apoA-I mimetic peptides prevent the development of flank tumors in immunocompetent C57BL/6J mice. To delineate the mechanism(s) of action of apoA-I mimetic peptides in tumor development, we examined the effect of D-4F (an apoA-I mimetic peptide) on the antioxidant status and on the gene expression and function of antioxidant enzymes in ID8 cells (a mouse epithelial ovarian cancer cell line) and in a mouse model. We demonstrate that D-4F treatment significantly reduces the viability and proliferation of ID8 cells, with a concomitant improvement of the antioxidant status of ID8 cells as measured by lipid peroxidation, protein carbonyl, superoxide anion, and hydrogen peroxide levels. D-4F treatment induces MnSOD (but not CuZnSOD) mRNA, protein, and activity. Inhibition of MnSOD in ID8 cells using shRNA vectors abrogates the inhibitory effects of D-4F on ID8 cell viability and proliferation. Moreover, tumor development from ID8 cells carrying shRNA for MnSOD were unaffected by D-4F treatment. Our results suggest that the inhibitory effects of D-4F on ID8 cell proliferation and tumor development are mediated, at least in part, by the induced expression and activity of MnSOD.     

Curcumin reverses diabetes‐induced endothelial progenitor cell dysfunction by enhancing MnSOD expression and activity in vitro and in vivo

Diabetes mellitus (DM) causes dysfunction of endothelial progenitor cells (EPCs), resulting in impaired wound healing. EPC therapy is a potential substitute to the current treatments of chronic wounds. Because EPCs isolated from diabetic patients are dysfunctional and therefore pose an obstacle in their efficacious employment in autologous cell therapy, a strategy to rescue them prior to transplantation would be expected to improve the efficacy of autologous cell therapy multifold. Compromised reactive oxygen species scavenging ability being the main cause of EPC dysfunction (EPCD), reactive oxygen species scavengers are likely to reverse or rescue EPCD. Therefore, in this study, we evaluated the potential of curcumin in reversing DM‐induced EPCD. We found that in vitro treatment of bone marrow EPCs from diabetic mice (D‐EPC) with curcumin restored their functionality, as judged by colony formation, tubule formation, and migration assays. Most importantly, autologous transplantation of curcumin‐treated D‐EPCs onto diabetic wounds also resulted in accelerated wound healing. Furthermore, curcumin‐treated diabetic mice exhibited improved wound healing, as compared with their vehicle‐treated diabetic counterparts, underscoring the efficacy of curcumin in vivo as well. The levels and activity of manganese superoxide dismutase (MnSOD) in D‐EPCs treated in vitro with curcumin or those isolated from curcumin‐treated diabetic mice were comparable with those in non‐diabetic EPCs. Addition of methyl mercury chloride to inhibit MnSOD activity during curcumin treatment abolished the salutary effects of curcumin. Our data demonstrate that curcumin reverses DM‐induced EPCD by boosting MnSOD expression and activity and emphasizes its potential for use in autologous cell therapy for diabetic wound management.     

Oxidative stress due to radiation in CD34+ Hematopoietic progenitor cells: protection by IGF-1

Radiation exerts direct as well as indirect effects on DNA through the generation of reactive oxygen species (ROS). Irradiated hematopoietic progenitor cells (HPCs) experience DNA strand breaks, favoring genetic instability, due to ROS generation. Our aim was to study the effect of a range of radiation doses in HPCs and the possible protective mechanisms activated by insulin-like growth factor-1 (IGF-1). ROS generation was evaluated, in the presence or absence of IGF-1 in liquid cultures of human HPCs-CD34⁺ irradiated with 1-, 2- and 5-Gy X-rays, using a flow cytometry assay. Manganese superoxide dismutase (MnSOD) expression was studied by western blot analysis and visualized by an immunofluorescence assay. Apoptosis was estimated using the following assays: Annexin-V assay, DNA degradation assay, BCL-2/BAX mRNA and protein levels and caspase-9 protein immunofluorescence visualization. Viability and clonogenic potential were studied in irradiated HPCs. The generation of superoxide anion radicals at an early and a late time point was increased, while the hydrogen peroxide generation at a late time point was stable. IGF-1 presence further enhanced the radiation-induced increase of MnSOD at 24 h post irradiation. IGF-1 inhibited the mitochondria-mediated pathway of apoptosis by regulating the m-RNA and protein expression of BAX, BCL-2 and the BCL-2/BAX ratio and by decreasing caspase-9 protein expression. IGF-1 presence in culture media of irradiated cells restored the clonogenic capacity and the viability of HPCs as well. In conclusion, IGF-1 protects HPCs-CD34⁺ from radiation effects, by eliminating the oxidative microenvironment through the enhancement of MnSOD activation and by regulating the mitochondria-mediated pathway of apoptosis.     

Manganese superoxide dismutase promotes interaction of actin,S100A4 and Talin,and enhances rat gastric tumor cell invasion

It has been demonstrated that cancer cells are under high levels of oxidative stress and express high levels of Manganese superoxide dismutase (MnSOD) to protect themselves and support the anabolic metabolism needed for growth and cell motility. The aim of this study was to identify proteins that may have a correlation with invasion and redox regulation by mitochondrial reactive oxygen species (ROS). MnSOD scavenges superoxide anions generated from mitochondria and is an important regulator of cellular redox status. Oxidative posttranslational modification of cysteine residues is a key mechanism that regulates protein structure and function. We hypothesized that MnSOD regulates intracellular reduced thiol status and promotes cancer invasion. A proteomic thiol-labeling approach with 5-iodoacetamidofluorescein was used to identify changes in intracellular reduced thiol-containing proteins. Our results demonstrate that overexpression of MnSOD maintained the major structural protein, actin, in a reduced state, and enhanced the invasion ability in gastric mucosal cancer cells, RGK1. We also found that the expression of Talin and S100A4 were increased in MnSOD-overexpressed RGK1 cells. Moreover, Talin bound not only with actin but also with S100A4, suggesting that the interaction of these proteins may, in part, contribute to the invasive ability of rat gastric cancer.     

Associations of Polymorphic Variant of MnSOD Gene with Breast Cancer in Residents of the Altai Region

The incidence of MnSOD genotypes in residents of the Altai Region suffering from breast cancer and individuals without a history of cancer corresponded to the Hardy-Weinberg equilibrium. No association of MnSOD with the incidence of sporadic breast cancer was detected. No association of MnSOD, tobacco smoking, or menopausal status, on the one hand, and breast cancer development, on the other, was detected. Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny , Vol. 147, No. 1, pp. 90-94, January, 2009     

糖尿病胃动力障碍大鼠胃窦平滑肌线粒体锰超氧化物歧化酶表达的变化

目的 通过STZ诱导糖尿病胃动力障碍大鼠模型制备,观察胃窦平滑肌线粒体锰超氧化物歧化酶（MnSOD）表达,探讨MnSOD在糖尿病胃动力障碍发生过程中的作用. 方法 Wistar大鼠随机分为模型（A）组和正常对照（B）组,4周后离体肌条实验确定糖尿病胃动力障碍模型建立,利用RT-PCR和Western blotting法检测胃窦平滑肌线粒体MnSOD的表达. 结果 （1）胃窦平滑肌自发性收缩活动频率A组（2.23±0.13）次/min,且收缩节律紊乱,B组（3.10±0.14）次/min;两组胃窦平滑肌收缩振幅比较差异有统计学意义（P＜0.01）;两组收缩振幅差异无统计学意义（P＞0.05）.（2） MnSOD mRNA表达（与β-actin的比值）B组（1.05±0.12）高于A组（0.43±0.13）（P＜0.01）.（3）MnSOD蛋白表达（与β-actin的比值）B组（0.54±0.06）高于A组（0.20±0.24）（P＜0.01）. 结论 STZ诱导4周后大鼠出现胃动力障碍;线粒体MnSOD在糖尿病胃动力障碍发生中起重要作用,可能与呼吸量缺陷至ATP供应不足有关.