C. elegans miro-1 Mutation Reduces the Amount of Mitochondria and Extends Life Span

Mitochondria play a critical role in aging, however, the underlying mechanism is not well understood. We found that a mutation disrupting the C. elegans homolog of Miro GTPase (miro-1) extends life span. This phenotype requires simultaneous loss of miro-1 from multiple tissues including muscles and neurons, and is dependent on daf-16/FOXO. Notably, the amount of mitochondria in the miro-1 mutant is reduced to approximately 50% of the wild-type. Despite this reduction, oxygen consumption is only weakly reduced, suggesting that mitochondria of miro-1 mutants are more active than wild-type mitochondria. The ROS damage is slightly reduced and the mitochondrial unfolded protein response pathway is weakly activated in miro-1 mutants. Unlike previously described long-lived mitochondrial electron transport chain mutants, miro-1 mutants have normal growth rate. These results suggest that the reduction in the amount of mitochondria can affect the life span of an organism through activation of stress pathways.     

Herbal Supplement Extends Life Span Under Some Environmental Conditions and Boosts Stress Resistance

Genetic studies indicate that aging is modulated by a great number of genetic pathways. We have used Drosophila longevity and stress assays to test a multipath intervention strategy. To carry out this strategy, we supplemented the flies with herbal extracts (SC100) that are predicted to modulate the expression of many genes involved in aging and stress resistance, such as mTOR, NOS, NF-KappaB, and VEGF. When flies were housed in large cages with SC100 added, daily mortality rates of both male and female flies were greatly diminished in mid to late life. Surprisingly, SC100 also stabilized midlife mortality rate increases so as to extend the maximum life span substantially beyond the limits previously reported for D. melanogaster. Under these conditions, SC100 also promoted robust resistance to partial starvation stress and to heat stress. Fertility was the same initially in both treated and control flies, but it became significantly higher in treated flies at older ages as the fertility of control flies declined. Mean and maximum life spans of flies in vials at the same test site were also extended by SC100, but the life spans were short in absolute terms. In contrast, at an independent test site where stress was minimized, the flies exhibited much longer mean life spans, but the survival curves became highly rectangular and the effects of SC100 on both mean and maximum life spans declined greatly or were abolished. The data indicate that SC100 is a novel herbal mix with striking effects on enhancing Drosophila stress resistance and life span in some environments, while minimizing mid to late life mortality rates. They also show that the environment and other factors can have transformative effects on both the length and distribution of survivorship, and on the ability of SC100 to extend the life span.     

Peroxiredoxin II Expression and Its Association With Oxidative Stress and Cell Proliferation in Human Idiopathic Pulmonary Fibrosis

Oxidant burden has been suggested to be a contributor to the pathogenesis of idiopathic pulmonary fibrosis (IPF). The study focused on peroxiredoxin (Prx) II, an antioxidant that has been associated with platelet-derived growth factor (PDGF) signaling and consequent cell proliferation. Localization and expression of Prx II, PDGF receptors (PDGFRα, PDGFRβ), Ki67, and nitrotyrosine were assessed in control (n=10) and IPF/usual interstitial pneumonia (UIP) (n=10) lung biopsies by immunohistochemistry and morphometry. Prx II oxidation was determined by standard and non-reducing Western blots, two-dimensional gel electrophoresis, and mass spectrometry. Prx II localized in the IPF/UIP epithelium and alveolar macrophages. Prx II–positive area in the fibroblastic foci (FF) was smaller than in other parenchymal areas (p=0.03) or in the hyperplastic epithelium (p=0.01). There was no major Prx II oxidation in IPF/UIP compared with the normal lung. The FF showed only minor immunoreactivity to the PDGFRs; Ki67, a marker of cell proliferation; and nitrotyrosine, a marker of oxidative/nitrosative stress. The results suggest that Prx II oxidation does not relate to the pathogenesis of IPF/UIP and that Prx II, PDGFRs, and proliferating cells colocalize in the IPF/UIP lung. Unexpectedly, FF represented areas of low cell proliferation. (J Histochem Cytochem 56:951–959, 2008)     

高氧胁迫下Peroxiredoxin2蛋白的细胞保护作用的研究

衰老和凋亡是细胞的两个重要生理过程,一直以来都是细胞生物学领域研究的热点。Peroxiredoxin 2(Prdx2)蛋白是过氧化物酶的其中一个亚型,分布于细胞质中。为了研究它在高氧条件诱导的细胞衰老及凋亡中的保护作用,我们分别将大鼠来源的Prdx2基因转染进人间充质干细胞(Human mesenchymal stem cells,hMSCs)和HEK293T细胞中,并建立了稳定表达Prdx2蛋白的HEK293T细胞系,利用SA-β-gal染色(Senescence-Associated β-Galactosidase Assay)、TUNEL染色及磷酸化p53蛋白的免疫印迹来检测高氧处理后细胞的衰老和凋亡情况。实验结果表明,高氧处理细胞后,转染了Prdx2的hMSCs和HEK293T细胞其衰老和凋亡率与对照组相比都有较为明显的减少,暗示Prdx2蛋白在细胞抵抗氧化损伤中发挥了重要作用。     

Senescence-Inducible Expression of Isopentenyl Transferase Extends Leaf Life, Increases Drought Stress Resistance and Alters Cytokinin Metabolism in Cassava

Cassava (Manihot esculenta Crantz) sheds its leaves during growth, especially within the tropical dry season. With the production of SAG12-IPT transgenic cassava we want to test the level of leaf retention and altered cytokinin metabolism of transgenic plants via the autoregulatory senescence inhibition system. After confirmation of transgene expression by molecular analysis and phenotype examination in greenhouse plants, two transgenic plant lines, 529-28 and 529-48, were chosen for further investigation. Detached mature leaves of 529-28 plants retained high levels of chlorophyll compared with wild-type leaves after dark-induced senescence treatment. Line 529-28 showed significant drought tolerance as indicated by stay-green capacity after drought stress treatment. Field experiments proved that leaf senescence syndrome was significantly delayed in 529-28 plants in comparison with wild-type and 529-48 plants. Physiological and agronomical characterizations of these plants also revealed that the induced expression of IPT had effects on photosynthesis, sugar allocation and nitrogen partitioning. Importantly, the 529-28 plants accumulated a high level of trans-zeatin-type cytokinins particularly of corresponding storage O-glucosides to maintain cytokinin homeostasis. Our study proves the feasibility of prolonging the leaf life of woody cassava and also sheds light on the control of cytokinin homeostasis in cassava leaves.     

降香通过抗氧化应激改善后负荷增加型心衰小鼠的心脏功能

目的:研究降香对后负荷增加引起的的心脏功能下降的保护作用及其机制。方法:雄性C57小鼠30只,随机分为三组,分别给予假手术(sham)、主动脉弓结扎(Transverse aortic constriction,TAC)手术和主动脉弓结扎手术降香治疗(TAC+DO)处理。通过灌胃给药4周,随后超声检测心脏功能、四腔心切片观察心肌重构,RT-PCR检测左心室αMHC、βMHC的m RNA表达、相应试剂盒心肌总抗氧化能力(TAOC)和丙二醇(MDA)含量。结果:同sham组相比,TAC组射血分数(EF),αMHC m RNA水平和TOAC均显著降低,且左室舒张末内径(LVIDd)、左室舒张期后壁厚度(LVPWd)、左室质量(LV mass)、心肌质量/胫骨长度(HW/TL)及β及β度、MDA均显著增加。同TAC组相比,DO组射血分数(EF),αMHC m RNA水平和TOAC均显著增加,且左室舒张末内径(LVIDd)、舒张末室间隔厚度(IVSd)、左室质量(LV mass)、心肌质量/胫骨长度(HW/TL)及βMHC、MDA均显著下降。在离体培养的心肌细胞,H_2O_2可显著增加细胞内ROS含量,给予降香或TEMPOL处理均可减轻H_2O_2诱导的氧化应激并增加心肌细胞存活率。结论:降香可通过降低氧化应激抑制线粒体分裂并改善后负荷增加型心衰的心脏功能。     

Lycium Barbarum (Wolfberry) Reduces Secondary Degeneration and Oxidative Stress,and Inhibits JNK Pathway in Retina after Partial Optic Nerve Transection

Our group has shown that the polysaccharides extracted from Lycium barbarum (LBP) are neuroprotective for retinal ganglion cells (RGCs) in different animal models. Protecting RGCs from secondary degeneration is a promising direction for therapy in glaucoma management. The complete optic nerve transection (CONT) model can be used to study primary degeneration of RGCs, while the partial optic nerve transection (PONT) model can be used to study secondary degeneration of RGCs because primary degeneration of RGCs and secondary degeneration can be separated in location in the same retina in this model; in other situations, these types of degeneration can be difficult to distinguish. In order to examine which kind of degeneration LBP could delay, both CONT and PONT models were used in this study. Rats were fed with LBP or vehicle daily from 7 days before surgery until sacrifice at different time-points and the surviving numbers of RGCs were evaluated. The expression of several proteins related to inflammation, oxidative stress, and the c-jun N-terminal kinase (JNK) pathways were detected with Western-blot analysis. LBP did not delay primary degeneration of RGCs after either CONT or PONT, but it did delay secondary degeneration of RGCs after PONT. We found that LBP appeared to exert these protective effects by inhibiting oxidative stress and the JNK/c-jun pathway and by transiently increasing production of insulin-like growth factor-1 (IGF-1). This study suggests that LBP can delay secondary degeneration of RGCs and this effect may be linked to inhibition of oxidative stress and the JNK/c-jun pathway in the retina.     

Conditioning Heat Stress Reduces Excitotoxic and Apoptotic Components of Oxygen-Glucose Deprivation-Induced Neuronal Death In Vitro

Abstract: We investigated the effects of sublethal heat stress in murine cortical cell cultures exposed to combined oxygen and glucose deprivation. Pretreatment with sublethal heat stress mildly attenuated the widespread neuronal death induced a day later by 30–60 min of oxygen-glucose deprivation. Heat stress also blunted the increase in extracellular glutamate concentrations induced by the oxygen-glucose deprivation, as well as the neuronal death and ⁴⁵Ca²⁺ uptake induced by exogenous addition of NMDA, although no reduction was seen in neuronal death caused by exogenous kainate or in NMDA-induced whole-cell currents. However, arguing against the idea that the neuroprotective effect of heat stress against neuronal death was exclusively due to reduction of excitotoxicity was the finding that heat stress also reduced the neuronal apoptosis induced by oxygen-glucose deprivation in the presence of glutamate antagonists. This antiapoptotic effect was specific in that heat stress did not reduce neuronal vulnerability to staurosporine-induced apoptosis. Whereas heat stress transiently suppressed protein synthesis, achieving comparable protein synthesis inhibition with cycloheximide did not reproduce the neuroprotective effects of heat stress. These studies suggest that a conditioning heat stress is able to attenuate both the excitotoxic and the apoptotic components of oxygen-glucose deprivation-induced neuronal death in vitro, by mechanisms independent of protein synthesis reduction.     

研究: 甲醛对果蝇寿命及其在应激条件下耐受性的影响

虽然甲醛对人及动物多种器官的毒性作用已经有了大量研究,但不同浓度甲醛影响动物寿命的研究还极其少见.本文用黑腹果蝇作为模式生物,在食物中添加不同浓度的甲醛,观察果蝇寿命及其在应激条件下耐受性的变化.实验结果显示,雌性果蝇的寿命表现出对甲醛浓度的依赖,0.037%甲醛可以极显著地延长雌性果蝇的寿命,较高浓度甲醛(≥0.185%)可以极显著地缩短雌性果蝇与雄性果蝇的寿命.0.037%甲醛还可以极显著地增强雌性和雄性果蝇对饥饿以及高温的耐受性,但减弱其对活性氧的耐受性.这些结果有助于从新的途径研究果蝇寿命及其在应激条件下耐受性的分子机制.     

Initiation of Neuronal Damage by Complex I Deficiency and Oxidative Stress in Parkinson's Disease

Oxidative stress and partial deficiencies of mitochondrial complex I appear to be key factors in the pathogenesis of Parkinson's disease. They are interconnected; complex I inhibition results in an enhanced production of reactive oxygen species (ROS), which in turn will inhibit complex I. Partial inhibition of complex I in nerve terminals is sufficient for in situ mitochondria to generate more ROS. H2O2 plays a major role in inhibiting complex I as well as a key metabolic enzyme, alpha-ketoglutarate dehydrogenase. The vicious cycle resulting from partial inhibition of complex I and/or an inherently higher ROS production in dopaminergic neurons leads over time to excessive oxidative stress and ATP deficit that eventually will result in cell death in the nigro-striatal pathway.     

The Priming of Potato Plants Induced by Brassinosteroids Reduces Oxidative Stress and Increases Salt Tolerance

This is the first study to show that brief pretreatment of potato plants with two brassinosteroids differing in structure causes in plants the ability to react to delayed salt stress by accumulation of compounds with antioxidant activity and by increased salt tolerance.     

Role ofRAS2in Recovery from Chronic Stress: Effect on Yeast Life Span

The replicative life span ofSaccharomyces cerevisiaewas previously shown to be modulated by the homologous signal transducers Ras1p and Ras2p in a reciprocal manner. We have used thermal stress as a life span modulator in order to uncover functional differences between theRASgenes that may contribute to their divergent effects on life span. Chronic exposure of cells throughout life to recurring heat shocks at sublethal temperatures decreased their replicative life span.ras2mutants, however, suffered the largest decrease compared to wild-type andras1mutant cells. The decrease was correlated with a substantial delay in resumption of budding upon recovery from these heat shocks, indicating an impaired renewal of cell cycling. Detailed analysis of gene expression showed that, during recovery,ras2mutants were selectively impaired in down-regulation of stress-responsive genes and up-regulation of growth-promoting genes. Our results suggest that one of the functions ofRAS2in maintaining life span, for whichRAS1does not substitute, is to ensure renewal of growth and cell division after bouts of stress that cells encounter during their life. This activity ofRAS2is effected by the cyclic AMP pathway. Overexpression ofRAS2,but notRAS2^ser42which is deficient in the activation of adenylate cyclase, completely reversed the effect of chronic stress on life span. Thus,RAS2is limiting for longevity in the face of chronic stress. SinceRAS2is known to down-regulate stress responses, this demonstrates that for longevity the ability to recover from stress is at least as important as the ability to mount a stress response.     

Endogenous Expression of ODN-Related Peptides in Astrocytes Contributes to Cell Protection Against Oxidative Stress: Astrocyte-Neuron Crosstalk Relevance for Neuronal Survival

Astroglial cells are important actors in the defense of brain against oxidative stress injuries. Glial cells synthesize and release the octadecaneuropeptide ODN, a diazepam-binding inhibitor (DBI)-related peptide, which acts through its metabotropic receptor to protect neurons and astrocytes from oxidative stress-induced apoptosis. The purpose of the present study is to examine the contribution of the endogenous ODN in the protection of astrocytes and neurons from moderate oxidative stress. The administration of H₂O₂ (50 μM, 6 h) induced a moderate oxidative stress in cultured astrocytes, i.e., an increase in reactive oxygen species, malondialdehyde, and carbonyl group levels, but it had no effect on astrocyte death. Mass spectrometry and QPCR analysis revealed that 50 μM H₂O₂ increased ODN release and DBI mRNA levels. The inhibition of ODN release or pharmacological blockage of the effects of ODN revealed that in these conditions, 50 μM H₂O₂ induced the death of astrocytes. The transfection of astrocytes with DBI siRNA increased the vulnerability of cells to moderate stress. Finally, the addition of 1 nM ODN to culture media reversed cell death observed in DBI-deficient astrocytes. The treatment of neurons with media from 50 μM H₂O₂-stressed astrocytes significantly reduced the neuronal death induced by H₂O₂; this effect is greatly attenuated by the administration of an ODN metabotropic receptor antagonist. Overall, these results indicate that astrocytes produce authentic ODN, notably in a moderate oxidative stress situation, and this glio- and neuro-protective agent may form part of the brain defense mechanisms against oxidative stress injury.     

Mitochondrial Glutathione Transport Is a Key Determinant of Neuronal Susceptibility to Oxidative and Nitrosative Stress

Mitochondrial oxidative stress significantly contributes to the underlying pathology of several devastating neurodegenerative disorders. Mitochondria are highly sensitive to the damaging effects of reactive oxygen and nitrogen species; therefore, these organelles are equipped with a number of free radical scavenging systems. In particular, the mitochondrial glutathione (GSH) pool is a critical antioxidant reserve that is derived entirely from the larger cytosolic pool via facilitated transport. The mechanism of mitochondrial GSH transport has not been extensively studied in the brain. However, the dicarboxylate (DIC) and 2-oxoglutarate (OGC) carriers localized to the inner mitochondrial membrane have been established as GSH transporters in liver and kidney. Here, we investigated the role of these carriers in protecting neurons from oxidative and nitrosative stress. Immunoblot analysis of DIC and OGC in primary cultures of rat cerebellar granule neurons (CGNs) and cerebellar astrocytes showed differential expression of these carriers, with CGNs expressing only DIC and astrocytes expressing both DIC and OGC. Consistent with these findings, butylmalonate specifically reduced mitochondrial GSH in CGNs, whereas both butylmalonate and phenylsuccinate diminished mitochondrial GSH in astrocytes. Moreover, preincubation with butylmalonate but not phenylsuccinate significantly enhanced susceptibility of CGNs to oxidative and nitrosative stressors. This increased vulnerability was largely prevented by incubation with cell-permeable GSH monoethylester but not malate. Finally, knockdown of DIC with adenoviral siRNA also rendered CGNs more susceptible to oxidative stress. These findings demonstrate that maintenance of the mitochondrial GSH pool via sustained mitochondrial GSH transport is essential to protect neurons from oxidative and nitrosative stress.     

白桦脂酸通过抗氧化应激作用抑制脂多糖诱导的血管收缩功能损伤

白桦脂酸（betulinic acid,BA）有良好的抗心血管氧化应激损伤作用。然而,BA对脂多糖lipopolysaccharide,LPS）诱导血管收缩功能损伤是否具有保护作用,该保护作用是否与抗氧化应激有关,尚不清楚。本研究给予雄性SD大鼠白桦脂酸灌胃（25 mg/kg/d,3 d）预处理,于第4 d腹腔注射LPS（10 mg/kg）,4 h后麻醉处死,分离血浆及胸主动脉,测定大鼠胸主动脉环收缩性,测定炎症因子白细胞介素6（interleukin-6,IL-6）及氧化应激指标。结果显示,白桦脂酸明显抑制LPS诱导的血浆及胸主动脉IL-6水平（P<0.01）,降低LPS对苯肾上腺素、KCl及Ca²⁺血管收缩反应的抑制作用（84.8%±9.09% vs 42.80%±9.00%,P<0.01;127.48%±12.02% vs 99.78%±6.02%,P<0.01;52.07%±13.48% vs 20.83%±5.04%,P<0.01）,减少LPS诱导的胸主动脉丙二醛水平（P<0.01）及诱导型一氧化氮合酶（inducible nitric oxide synthase,iNOS）活性（P<0.01）,缓解LPS对超氧化物歧化酶（superoxide dismutase,SOD）的抑制作用（P<0.01）。上述结果提示,白桦脂酸抑制LPS诱导血管收缩功能障碍的机制可能与增加机体SOD活性,抑制氧化应激及iNOS活性有关。     

Regulation of Gene Expression Is Linked to Life Span in Adult Drosophila

Examination of gene expression and aging in adult Drosophila reveals that the expression of some genes is regulated by age-dependent mechanisms. Genetic mutations, Hyperkinetic(1) and Shaker(5), which are known to shorten life span through an acceleration of the aging process, were used to study the expression of an enhancer trap marked gene. The temporal pattern of expression for such a marked gene shows scaling with respect to life span; it is altered in direct proportion to the life expectancy of the adult animal. This demonstrates that expression of this gene is controlled through mechanisms coupled to physiologic as opposed to chronologic age. Results provide direct evidence for linkage between the regulation of gene expression and life span and establish a model system for the genetic analysis of aging.