Mitochondrial antioxidative capacity regulates muscle glucose uptake in the conscious mouse: effect of exercise and diet
Li KangMary E. LustigJeffrey S. BonnerRobert S. LeeWesley H. MayesFreyja D. JamesChien‐Te LinChristopher G. R. PerryEthan J. AndersonP. Darrell NeuferDavid H. Wasserman
12
Citation
65
Reference
10
Related Paper
Citation Trend
Abstract:
The objective of this study was to test the hypothesis that exercise-stimulated muscle glucose uptake (MGU) is augmented by increasing mitochondrial reactive oxygen species (mtROS) scavenging capacity. This hypothesis was tested in genetically altered mice fed chow or a high-fat (HF) diet that accelerates mtROS formation. Mice overexpressing SOD2 ( sod2 Tg ), mitochondria-targeted catalase ( mcat Tg ), and combined SOD2 and mCAT (mtAO) were used to increase mtROS scavenging. mtROS was assessed by the H 2 O 2 emitting potential ( JH 2 O 2 ) in muscle fibers. sod2 Tg did not decrease JH 2 O 2 in chow-fed mice, but decreased JH 2 O 2 in HF-fed mice. mcat Tg and mtAO decreased JH 2 O 2 in both chow- and HF-fed mice. In parallel, the ratio of reduced to oxidized glutathione (GSH/GSSG) was unaltered in sod2 Tg in chow-fed mice, but was increased in HF-fed sod2 Tg and both chow- and HF-fed mcat Tg and mtAO. Nitrotyrosine, a marker of NO-dependent, reactive nitrogen species (RNS)-induced nitrative stress, was decreased in both chow- and HF-fed sod2 Tg , mcat Tg , and mtAO mice. This effect was not changed with exercise. Kg, an index of MGU was assessed using 2-[ 14 C]-deoxyglucose during exercise. In chow-fed mice, sod2 Tg , mcat Tg , and mtAO increased exercise Kg compared with wild types. Exercise Kg was also augmented in HF-fed sod2 Tg and mcat Tg mice but unchanged in HF-fed mtAO mice. In conclusion, mtROS scavenging is a key regulator of exercise-mediated MGU and this regulation depends on nutritional state.Keywords:
SOD2
Mitochondrial ROS
Corneal endothelial cells are rich in mitochondria, a potential source of reactive oxygen species (ROS). ROS have been implicated in endothelial cell loss during aging or in endothelial dystrophies. In this study we examined the anti-oxidative role of mitochondrial superoxide dismutase (SOD2) in corneal endothelial cells.SOD2 expression was examined by RT-PCR and western blot analysis in fresh rabbit corneal endothelium (RCE) and cell cultures. SOD2 activity, total reactive oxygen species (ROS), mitochondrial ROS, mitochondrial membrane potential (MMP), and apoptotic levels were examined in untreated, SOD2 siRNA and viral vector shRNA treated RCE cells. Scrambled siRNA and shRNA sequence targeting non-mammalian genes were used as controls.SOD2 is expressed in both fresh and cultured rabbit corneal endothelium. SOD2 expression was reduced by ~80%-90% in cultured RCE using either siRNA or shRNA approaches. SOD2 activity was decreased by ~70%-80% for both approaches. Total cell ROS was significantly increased in shSOD2 lentivirus treated cells (9%±6%) relative to control transduction (0.4%±0.1%). MitoSOX™ staining for mitochondrial ROS in siSOD2 treated RCE cells was dramatically increased. Two minutes of UV irradiation increased total ROS levels by 15%, whereas in shSOD2 treated cells UV induced ROS was increased 29%±5% (p<0.05). MMP was reduced in shSOD2 viral treated cells by 66%±3%, significantly greater than in control transduced cells (15%±8%, p<0.05). Apoptosis increased by 1.5 fold in shSOD2 virus treated samples compared with scrambled virus and untreated cells.SOD2 is expressed in both fresh and cultured rabbit corneal endothelium. siRNA and shRNA approaches are able to efficiently knockdown SOD2 expression and reduce enzyme activity in RCE cells. Decreased SOD2 activity causes elevated ROS production, mitochondrial membrane potential loss and early cell apoptosis. These results indicate that SOD2 is a significant anti-oxidative enzyme in RCE cells.
SOD2
Mitochondrial ROS
Corneal Endothelium
Cite
Citations (19)
The formal genetics of superoxide dismutase has been studied in a family material from northern Sweden. The results verify the hypothesis that the three phenotypes SOD 1, SOD 2–1 and SOD 2 are controlled by two autosomal alleles. Although the SOD2 gene appears to be associated with somewhat lower enzyme activity, the SOD 2–1 and SOD 2 types were found not be associated with disease.
SOD2
Cite
Citations (8)
Oxygen toxicity
Cite
Citations (15)
Aim: Mitochondria are major sites of reactive oxygen species (ROS) generation, and adaptive mitochondrial ROS signaling extends longevity. We aim at linking the genetic manipulation of mitochondrial H2O2 sensing in live cells to mechanisms driving aging in the model organism, Saccharomyces cerevisiae. To this end, we compare in vivo ROS (O2•−, H2O2 and •OH) accumulation, antioxidant enzyme activities, labile iron levels, GSH depletion, and protein oxidative damage during the chronological aging of three yeast strains: ccp1Δ that does not produce the mitochondrial H2O2 sensor protein, cytochrome c peroxidase (Ccp1); ccp1W191F that produces a hyperactive variant of this sensor protein (Ccp1W191F); and the isogenic wild-type strain. Results: Since they possess elevated manganese superoxide dismutase (Sod2) activity, young ccp1Δ cells accumulate low mitochondrial superoxide (O2•−) levels but high H2O2 levels. These cells exhibit stable aconitase activity and contain low amounts of labile iron and hydroxyl radicals (•OH). Furthermore, they undergo late glutathione (GSH) depletion, less mitochondrial protein oxidative damage and live longer than wild-type cells. In contrast, young ccp1W191F cells accumulate little H2O2, possess depressed Sod2 activity, enabling their O2•− level to spike and deactivate aconitase, which, ultimately, leads to greater mitochondrial oxidative damage, early GSH depletion, and a shorter lifespan than wild-type cells. Innovation: Modulation of mitochondrial H2O2 sensing offers a novel interventional approach to alter mitochondrial H2O2 levels in live cells and probe the pro- versus anti-aging effects of ROS. Conclusion: The strength of mitochondrial H2O2 sensing modulates adaptive mitochondrial ROS signaling and, hence, lifespan. Antioxid. Redox Signal. 21, 1490–1503.
SOD2
Mitochondrial ROS
Proteostasis
Cite
Citations (20)
SOD2
Dismutase
Cite
Citations (811)
Some commercial samples of bovine catalase contain superoxide dismutase activity. Therefore the inhibition of a reaction on the addition of a catalase preparation need not necessarily mean that H2O2 is responsible for the reaction.
Cite
Citations (67)
Cite
Citations (102)
Current therapy for Alzheimer's disease (AD) focuses on delaying progression, illustrating the need for more effective therapeutic targets. Increases in reactive oxygen species (ROS) in the brain link multiple hypotheses for the cause of AD. Mouse models display elevations in ROS prior to both Aß plaque and neurofibrillary tangle formation. In particular, elevations in mitochondrial ROS as a result of Aß aggregation have been observed throughout AD pathology. Antioxidant trials have produced mixed results in mouse models and patients, perhaps due to lack of specificity and targeting. Learning and memory deficits are present in the Tg2576 model of AD prior to plaque formation and ROS elevation. In addition, recent studies have linked mitochondria specific antioxidant, superoxide dismutase 2 (SOD2) with recovery of AD pathology in the Tg2576 mouse model of AD. When Tg2576 mice were crossed with mice that overexpress SOD2, (Tg2576/SOD2 mice) both learning and memory impairment as well as plaque burden were improved, indicating that mitochondrial ROS may play a large role in AD pathogenesis. In order to identify the possible source of ROS, we conducted an investigation in vitro using PC12 cells treated with Aß to examine changes in mitochondrial ROS using both cytosolic (DCFH) and mitochondrial (MitoSOX) ROS dyes. We show that Aß1-42 specifically increased ROS from the mitochondria in a dose dependent manner. Mean fluorescence intensity for DCFH was 220.578 [0uM], 278.258 [1uM], and 289.349 [5uM], whereas MitoSOX intensity was 325.17 [0uM], 363.415 [1uM], and 850.718 [5uM]. These results demonstrate both that the source of ROS likely mitochondrial superoxide and its relationship to a sub-lethal concentration of Aß1-42. In addition, using sub-cellular site-specific redox probes directed to the mitochondria we are assessing the contribution of mitochondrial superoxide (mito-cpYFP) and hydrogen peroxide (pHyper-dMito) to the Aß induced ROS burden in neurons. Our findings implicate the development of specific, targeted mitochondrial antioxidants for AD patients. Identifying the sub-cellular source, the specific ROS species produced, and the mechanisms by which increased mitochondrial ROS influence neuronal function in AD will allow for the development of more effective targeted therapeutic interventions to combat the deleterious effects of this devastating disease.
SOD2
Mitochondrial ROS
Cite
Citations (0)
Activation of T‐cells and increased superoxide production are crucial in the development of hypertension (J Exp Med. 2007; 204:2449). Interestingly, depletion of mitochondrial superoxide dismutase (SOD2) increases hypertension while SOD2 overexpression blunts hypertension (Circ Res. 2010; 107:106). We hypothesized that mitochondrial superoxide plays an important role in T‐cell activation and pro‐hypertensive immune response. In order to test this hypothesis we investigated the effect of mitochondria targeted SOD2 mimetic mitoTEMPO and SOD2 expression (SOD2+/− or SOD2 overexpression) on T cell activation and pro‐hypertensive immune effect by adaptive transfer of T‐cells in RAG1 KO mice. Preliminary analysis of spleenocytes from hypertensive mice infused with angiotensin II showed decrease in mitochondrial membrane potential, increase in mitochondrial superoxide and cellular ATP that is consistent with attenuated mitochondrial function and activation of redox dependent glycolysis. Indeed, treatment of spleenocytes with mitochondria targeted antioxidant mitoTEMPO significantly blunted these changes. Since T‐cells are essential in pro‐hypertensive immune response, we isolated T‐cell fraction from spleenocytes and studied the role of mitochondrial superoxide in T‐cells proliferation and cytokine production. T‐cells isolated from hypertensive mice showed three fold increased cell proliferation and TNF‐α secretion which was blocked by treatment of T‐cells with mitoTEMPO. Therefore, this work suggets that mitochondrial superoxide is essential in T‐cells metabolic changes, activation and pro‐hypertensive immune response.
SOD2
Mitochondrial ROS
Cite
Citations (2)
Dismutase
White (mutation)
Cite
Citations (30)