The role of nutrition and oxidative stress as aging factors in Caenorhabditis elegans.

The molecular mechanism of aging, which has been a "black box" for many years, has been elucidated in recent years, and the nematode C. elegans, which is a model animal for aging research, has played a major role in its elucidation. From the analysis of C. elegans longevity-related mutant genes, many signal transduction systems, with the insulin/insulin-like growth factor signal transduction system at the core, have emerged. It has become clear that this signal transduction system is greatly affected by external nutrients and is involved in the downstream regulation of oxidative stress, which is considered to be one of the main causes of aging.

Streptococcus thermophilus extends lifespan through activation of DAF-16-mediated antioxidant pathway in Caenorhabditis elegans.

Streptococcus thermophilus bacteria, which are widely used as fermented starter for dairy production, exert various beneficial health effects. Nevertheless, even though pro-longevity effects of various probiotics have been reported, no report has described Streptococcus thermophilus effects on longevity. This study was conducted to evaluate Streptococcus thermophilus effects on lifespan extension and to elucidate the Streptococcus thermophilus-mediated longevity mechanism using Caenorhabditis elegans worms as a model animal. They were fed standard food (Escherichia coli OP50) or Streptococcus thermophilus from the young adult stage. Feeding with Streptococcus thermophilus, compared to Escherichia coli OP50, to Caenorhabditis elegans extend the lifespan, reduced lipofuscin accumulation, and maintain vigorous locomotion. Feeding with Streptococcus thermophilus did not alter the worm growth curve or the offspring number, indicating that the Streptococcus thermophilus-mediated lifespan extension is not attributable to caloric restriction. The qRT-PCR data showed that Streptococcus thermophilus increased the expression of daf-16 and some of its downstream antioxidant genes. Furthermore, the pro-longevity effects of Streptococcus thermophilus were decreased in loss-of-function mutant of daf-16. Results show that Streptococcus thermophilus extends the lifespan of Caenorhabditis elegans through DAF-16-mediated antioxidant pathway activation.

Metabolic Biomarkers in Nematode C. elegans During Aging.

Changes in energy metabolism occur not only in diseases such as cancer but also in the normal development and aging processes of various organisms. These metabolic changes result to lead to imbalances in energy metabolism related to cellular and tissue homeostasis. In the model organism C. elegans, which is used to study aging, an imbalance in age-related energy metabolism exists between mitochondrial oxidative phosphorylation and aerobic glycolysis. Cellular lactate and pyruvate are key intermediates in intracellular energy metabolic pathways and can indicate age-related imbalances in energy metabolism. Thus, the cellular lactate/pyruvate ratio can be monitored as a biomarker during aging. Moreover, recent studies have proposed a candidate novel biomarker for aging and age-related declines in the nematode C. elegans.

Clinical practice guidance for next-generation sequencing in cancer diagnosis and treatment (Edition 1.0).

In Japan, the social (medical) health-care system is on the way to being developed to advance personalized medicine through the implementation of cancer genomic medicine, known as "cancer clinical sequencing," which uses a next-generation sequencer. However, no Japanese guidance for cancer genomic testing exists. Gene panel testing can be carried out to help determine patient treatment, confirm diagnosis, and evaluate prognostic predictions of patients with mainly solid cancers for whom no standard treatment is available. This guidance describes how to utilize gene panel testing according to the type of cancer: childhood cancer, rare cancer, carcinoma of unknown primary, and other cancers. The level of evidence classification for unified use in Japan is also detailed. This guidance establishes the basic principles of the quality control of specimens, requirements of medical institutions, informed consent, handling of data during the postanalysis stage, and treatment options based on the evidence level. In Japan, gene panel testing for cancer treatment and diagnosis is recommended to comply with this guidance. This is a collaborative work of the Japanese Society of Medical Oncology, Japan Society of Clinical Oncology, and the Japanese Cancer Association.

Impaired p53/CEP-1 is associated with lifespan extension through an age-related imbalance in the energy metabolism of C. elegans.

In the nematode Caenorhabditis elegans, the mammalian tumor suppressor p53 ortholog CEP-1 mediates the stress response, activates germ line apoptosis and regulates meiotic chromosome segregation. A reduction in its expression, which frequently occurs in mammalian cancer cells, extends lifespan and induces an adaptive response in C. elegans. However, these effects do not involve an increase in oxidative stress resistance. Here, we showed that intermittent exposure to hyperoxia, which induces oxidative stress resistance and lowers the production of ROS derived from mitochondrial respiration in C. elegans, slightly improved the lifespan extension of cep-1 mutant. Interestingly, ATP levels were increased without an increase in oxygen consumption in cep-1 mutant during aging. In the wild-type, lactate levels and consequentially the lactate/pyruvate ratio decreased during aging in adults. Furthermore, the expression levels of mitochondrial respiration-related sco-1, which is a target of p53/CEP-1, as well as those of gluconeogenesis regulation and mammalian sirtuin ortholog genes, were also increased in the aged and adaptive conditioned wild-type animals. In contrast, the lactate/pyruvate ratio increased in cells of the cep-1 mutant and was amplified by intermittent hyperoxia. These results suggest that impaired p53/CEP-1 leads to an imbalance in the age-related energy metabolic alteration between mitochondrial oxidative phosphorylation and aerobic glycolysis and plays an important role in the extension of both intact and adaptive lifespans.

Model animals for the study of oxidative stress from complex II.

Mitochondria play a role of energy production and produce intracellular reactive oxygen species (ROS), especially superoxide anion (O2(-)) as a byproduct of energy metabolism at the same time. O2(-) is converted from oxygen and is overproduced by excessive electron leakage from the mitochondrial respiratory chain. It is well known that mitochondrial complexes I and III in the electron transport system are the major endogenous ROS sources. We have previously demonstrated that mutations in complex II can result in excessive ROS (specifically in SDHC: G71E in Caenorhabditis elegans, I71E in Drosophila and V69E in mouse). Moreover, this results in premature death in C. elegans and Drosophila as well as tumorigenesis in mouse embryonic fibroblast cells. In humans, it has been reported that mutations in SDHB, SDHC or SDHD, which are the subunits of mitochondrial complex II, often result in inherited head and neck paragangliomas (PGLs). Recently, we established Tet-mev-1 conditional transgenic mice using our uniquely developed Tet-On/Off system, which can induce the mutated SDHC gene to be equally and competitively expressed compared to the endogenous wild-type SDHC gene. These mice experienced mitochondrial respiratory chain dysfunction that resulted in oxidative stress. The mitochondrial oxidative stress caused excessive apoptosis in several tissues leading to low-birth-weight infants and growth retardation during neonatal developmental phase in Tet-mev-1 mice. Tet-mev-1 mice also displayed precocious age-dependent corneal physiological changes, delayed corneal epithelialization, decreased corneal endothelial cells, thickened Descemet's membrane and thinning of parenchyma with corneal pathological dysfunctions such as keratitis, Fuchs' corneal dystrophy (FCD) and probably keratoconus after the normal development and growth phase. Here, we review the relationships between mitochondrial oxidative stress and phenomena in mev-1 animal models with mitochondrial complex II SDHC mutations. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.

Nuclear envelope localization of Ran-binding protein 2 and Ran-GTPase-activating protein 1 in psoriatic epidermal keratinocytes.

The nuclear localization signal (NLS)-containing proteins LEDGF and STAT3 localize to the nucleus in both the spinous and basal layers of the epidermis in psoriatic skin, where they function as transcription factors or co-factors to activate epidermal keratinocytes (KCs). However, the mechanism underlying the localization of these proteins remains to be elucidated. We investigated the differential nucleocytoplasmic transport of NLS-containing proteins as a potential pathogenic mechanism for psoriasis vulgaris. Nucleoporins play an important role in the Ran-GTP-dependent nucleocytoplasmic transport of NLS-containing proteins. We showed, using immunohistochemical staining, that the nucleoporins Ran-binding protein 2 (RanBP2) and Ran-GTPase-activating protein 1 (RanGAP1) have greater expression on the nuclear envelope in psoriatic epidermal KCs than in KCs from healthy controls. We then studied the signalling pathways involved in the regulation of these proteins in HaCaT cells. The two major downstream pathways of epidermal growth factor receptor (EGFR) signalling activated in psoriatic KCs are the MAPK/Erk/1/2 and the phosphatidylinositol-3-kinase/Akt pathways. Therefore, we treated HaCaT cells with inhibitors to disrupt the MAP kinase kinase 1 (MEK1), PI3-kinase, or mTOR pathways. RanBP2 and RanGAP1 protein expression levels were significantly greater in the nuclear envelope of HaCaT cells that were not treated with inhibitors than in cells treated with a combination of PI3-kinase and MEK1 inhibitors or mTOR and MEK1 inhibitors. These results suggest that adequate nuclear envelope expression of RanBP2 and RanGAP1 could be a prerequisite for nucleocytoplasmic transport in KCs in psoriatic epidermis.

Liposome-encapsulated hemoglobin enhances chemotherapy to suppress metastasis in mice.

Liposome-encapsulated hemoglobin with high O2 -affinity (P50 O2 = 10 mm Hg, h-LEH) was reported to enhance tumor radiosensitivity. We hypothesize that targeted O2 delivery to tumor hypoxia by h-LEH may also enhance chemotherapy to suppress tumor growth and metastasis in mice. Doxorubicin (DXR; 0.5 or 2 mg/kg i.p.) or S-1 (4 or 8 mg/kg orally) alone or in combination with h-LEH (5 mL/kg i.v.) was administered for 2 weeks to C57BL/6N mice inoculated with Lewis Lung Carcinoma (LLC) in the leg. After the 2-week therapy in six treatment groups, mice were sacrificed for quantitative assessment of tumor growth and lung metastasis. The tumor was then evaluated for its expression of hypoxia-inducible factor-1α (HIF-1α) and matrix metallopoteinase-2 (MMP-2) activity. Combined use of h-LEH and chemotherapeutic agents (DXR or S-1) showed no additional enhancement on suppression of the tumor growth over the chemotherapeutic agent alone. However, the combination use of h-LEH significantly suppressed the number and total area of metastatic colonies in the lung compared with each chemotherapeutic agent alone. Although HIF-1α expression and MMP-2 activity in the original tumor was significantly suppressed in the groups of mice treated with either DXR or S-1 alone, the addition of h-LEH to either agent showed further enhancement of oxygen-mediated degradation of HIF-1α and suppression of MMP-2 activity. Although the addition of h-LEH to DXR or S-1 had little effect on original LLC tumor growth, it significantly enhanced suppression of lung metastasis in mice.

Ingestion of taxifolin-rich foods affects brain activity, mental fatigue, and the whole blood transcriptome in healthy young adults: a randomized, double-blind, placebo-controlled, crossover study.

The antioxidant properties of polyphenols, which are found in most plants, have been shown to be useful for maintaining health, including enhancing brain function and alleviating stress. We aimed to investigate the effect of a single intake of taxifolin-containing foods on cognitive task performance and whole blood gene expression in healthy young adults. This study was a randomized, placebo-controlled, double-blind, crossover trial in which healthy young adults were administered a single dose of either a placebo or food containing taxifolin. Cognitive tests (serial 3s, serial 7s, and rapid visual information processing) to examine brain activity and visual analog scale questionnaires to analyze mental fatigue were applied. The set of tests was repeated four times. The findings showed that taxifolin intake improved calculation abilities and reduced mental fatigue. An analysis of whole blood gene expression before and after the test revealed that the expression of foreign substance removal-related genes increased following the ingestion of taxifolin and that most differentially expressed genes were enriched in granulocytes. Taxifolin intake was shown to affect the brain activity of healthy young adults and demonstrated an antifatigue effect, thereby reducing subjective fatigue. A single intake of taxifolin may enhance the removal of foreign substances by strengthening the innate immune system and suppressing the occurrence of injury.

Correction: Ingestion of taxifolin-rich foods affects brain activity, mental fatigue, and the whole blood transcriptome in healthy young adults: a randomized, double-blind, placebo-controlled, crossover study.

Correction for 'Ingestion of taxifolin-rich foods affects brain activity, mental fatigue, and the whole blood transcriptome in healthy young adults: a randomized, double-blind, placebo-controlled, crossover study' by Fumika Shinozaki et al., Food Funct., 2023, https://doi.org/10.1039/d2fo03151e.

A mutation in a mitochondrial dehydrogenase/reductase gene causes an increased sensitivity to oxidative stress and mitochondrial defects in the nematode Caenorhabditis elegans.

rad-8 is an interesting mutant that shows increased sensitivities to UV radiation and reactive oxygen species in the nematode Caenorhabditis elegans. In this study, we have characterized rad-8 and have found that rad-8 showed several phenotypes of mitochondrial dysfunction such as a decreased activity of the respiratory chain, increased generation of superoxide anions, increased oxidative damage, increased apoptosis, and abnormal mitochondrial structure. Our genetic analysis has also indicated that rad-8 has a causative mutation in the F56H1.6 gene, which encodes a mitochondrial dehydrogenase/reductase. The functional role of RAD-8 may be evolutionarily conserved because expression of the putative human homologue RTN4IP/NIMP in rad-8 rescued the increased sensitivity to oxygen in rad-8. These results suggest that RAD-8 plays an important role in oxygen metabolism in mitochondria in higher eukaryotes.

Interrelationships between mitochondrial fusion, energy metabolism and oxidative stress during development in Caenorhabditis elegans.

Mitochondria are known to be dynamic structures with the energetically and enzymatically mediated processes of fusion and fission responsible for maintaining a constant flux. Mitochondria also play a role of reactive oxygen species production as a byproduct of energy metabolism. In the current study, interrelationships between mitochondrial fusion, energy metabolism and oxidative stress on development were explored using a fzo-1 mutant defective in the fusion process and a mev-1 mutant overproducing superoxide from mitochondrial electron transport complex II of Caenorhabditis elegans. While growth and development of both single mutants was slightly delayed relative to the wild type, the fzo-1;mev-1 double mutant experienced considerable delay. Oxygen sensitivity during larval development, superoxide production and carbonyl protein accumulation of the fzo-1 mutant were similar to wild type. fzo-1 animals had significantly lower metabolism than did N2 and mev-1. These data indicate that mitochondrial fusion can profoundly affect energy metabolism and development.

Reviewing the Effects of Skin Manipulations on Adult Newt Limb Regeneration: Implications for the Subcutaneous Origin of Axial Pattern Formation.

Newts are unique salamanders that can regenerate their limbs as postmetamorphic adults. In order to regenerate human limbs as newts do, it is necessary to determine whether the cells homologous to those contributing to the limb regeneration of adult newts also exist in humans. Previous skin manipulation studies in larval amphibians have suggested that stump skin plays a pivotal role in the axial patterning of regenerating limbs. However, in adult newts such studies are limited, though they are informative. Therefore, in this article we have conducted skin manipulation experiments such as rotating the skin 180° around the proximodistal axis of the limb and replacing half of the skin with that of another location on the limb or body. We found that, contrary to our expectations, adult newts robustly regenerated limbs with a normal axial pattern regardless of skin manipulation, and that the appearance of abnormalities was stochastic. Our results suggest that the tissue under the skin, rather than the skin itself, in the intact limb is of primary importance in ensuring the normal axial pattern formation in adult newt limb regeneration. We propose that the important tissues are located in small areas underlying the ventral anterior and ventral posterior skin.

Interaction between the ins/IGF-1 and p38 MAPK signaling pathways in molecular compensation of sod genes and modulation related to intracellular ROS levels in C. elegans.

Superoxide dismutases, which catalytically remove intracellular superoxide radicals by the disproportionation of molecular oxygen and hydrogen peroxide, are encoded by the sod-1 to -5 genes in the nematode C. elegans. Expression of the sod genes is mutually compensatory for the modulation of intracellular oxidative stress during aging. Interestingly, several-fold higher expression of the sod-1 to -4 was induced in a sod-5 deletion mutant, despite the low expression levels of sod-5 in wild-type animals. Consequently, this molecular compensation facilitated recovery of lifespan in the sod-5 mutant. In previous reports, two transcription factors DAF-16 and SKN-1 are associated with the compensatory expression of sod genes, which are downstream targets of the ins/IGF-1 and p38 MAPK signaling pathways activated under oxidative and heavy metal stresses, respectively. Here, we show that p38 MAPK signaling regulates induction of not only the direct expression of sod-1, -2 and -4 but also the indirect modulation of DAF-16 targets, such as sod-3 and -5 genes. Moreover, a SKN-1 target, the insulin peptide gene ins-5, partially mediates the expression of DAF-16 targets via p38 MAPK signaling. These findings suggest that the interaction of ins/IGF-1 and p38 MAPK signaling pathways plays an important role in the fine-tuning of molecular compensation among sod genes to protect against mitochondrial oxidative damage during aging.

The role of mitochondrial superoxide anion (O2(-)) on physiological aging in C57BL/6J mice.

Much attention has been focused on the mitochondrial superoxide anion (O2(-)), which is also a critical free radial produced by ionizing radiation. The specific role of the mitochondrial O2(-) on physiological aging in mammals is still unclear despite wide-spread evidence that oxidative stress is involved in aging and age-related diseases. The major endogenous source of O2(-) is generated as a byproduct of energy metabolism from mitochondria. In order to better understand how O2(-)relates to metazoan aging, we have comprehensively examined age-related changes in the levels of oxidative damage, mitochondrial O2(-) production, mitochondrial antioxidant enzyme activity and apoptosis induction in key organs of an inbred mouse strain (C57BL/6J). Oxidative damage accumulated and excess apoptosis occurred in the brain, oculus and kidney with aging, but comparatively little occurred in the heart and muscle. These rates are correlated with O2(-) levels. Mitochondrial O2(-) production levels increased with aging in the brain, oculus and kidney, and did not significantly increased in the heart and muscle. In contrast to O2(-) production, mitochondrial SOD activities increased in heart and muscle, and remained unchanged in the brain, oculus and kidney with aging. These results suggest that O2(-) production has high organ specificity, and oxidative damage by O2(-) from mitochondria mediated apoptosis can lead to organ atrophy and physiological dysfunction. In addition, O2(-) from mitochondria plays a core role in physiological aging.

Monitoring Age-Related Changes in the Lactate/Pyruvate Ratio Using a Colorimetric Assay in a C. elegans Model of Increased Life Span.

In the nematode Caenorhabditis elegans (C. elegans), monitoring the lactate/pyruvate ratio in cells helps to detect imbalances in age-related energy metabolism. Here, we describe a modified small-scale extraction in C. elegans and measurement of lactate and pyruvate concentrations using colorimetric assay kits. During sample extraction, protein precipitation is the most critical step for precise determination of intracellular metabolites in C. elegans. Moreover, improved sensitivity and accuracy of colorimetric assay kits contributed to measurements of metabolites in samples derived from small-scale extraction. Using these protocols, we recently detected a metabolic alteration that occurs during aging by the monitoring the lactate/pyruvate ratio in a long-lived mutant of the mammalian tumor suppressor p53 ortholog CEP-1 in C. elegans.

Mutant alpha-galactosidase A enzymes identified in Fabry disease patients with residual enzyme activity: biochemical characterization and restoration of normal intracellular processing by 1-deoxygalactonojirimycin.

Fabry disease is a lysosomal storage disorder caused by the deficiency of alpha-Gal A (alpha-galactosidase A) activity. In order to understand the molecular mechanism underlying alpha-Gal A deficiency in Fabry disease patients with residual enzyme activity, enzymes with different missense mutations were purified from transfected COS-7 cells and the biochemical properties were characterized. The mutant enzymes detected in variant patients (A20P, E66Q, M72V, I91T, R112H, F113L, N215S, Q279E, M296I, M296V and R301Q), and those found mostly in mild classic patients (A97V, A156V, L166V and R356W) appeared to have normal K(m) and V(max) values. The degradation of all mutants (except E59K) was partially inhibited by treatment with kifunensine, a selective inhibitor of ER (endoplasmic reticulum) alpha-mannosidase I. Metabolic labelling and subcellular fractionation studies in COS-7 cells expressing the L166V and R301Q alpha-Gal A mutants indicated that the mutant protein was retained in the ER and degraded without processing. Addition of DGJ (1-deoxygalactonojirimycin) to the culture medium of COS-7 cells transfected with a large set of missense mutant alpha-Gal A cDNAs effectively increased both enzyme activity and protein yield. DGJ was capable of normalizing intracellular processing of mutant alpha-Gal A found in both classic (L166V) and variant (R301Q) Fabry disease patients. In addition, the residual enzyme activity in fibroblasts or lymphoblasts from both classic and variant hemizygous Fabry disease patients carrying a variety of missense mutations could be substantially increased by cultivation of the cells with DGJ. These results indicate that a large proportion of mutant enzymes in patients with residual enzyme activity are kinetically active. Excessive degradation in the ER could be responsible for the deficiency of enzyme activity in vivo, and the DGJ approach may be broadly applicable to Fabry disease patients with missense mutations.

Small-Scale Colorimetric Assays of Intracellular Lactate and Pyruvate in the Nematode Caenorhabditis elegans.

Lactate and pyruvate are key intermediates of intracellular energy metabolic pathways. Monitoring the lactate/pyruvate ratio in cells helps to determine whether there is an imbalance in age-related energy metabolism between mitochondrial oxidative phosphorylation and aerobic glycolysis. Here, we show the utilization of commercial colorimetric assay kits for lactate and pyruvate in the model organism C. elegans. Recently, the sensitivity and accuracy of the colorimetric/fluorimetric assay kits have been improved greatly by the research and development conducted by reagent manufacturers. The improved reagents have enabled the use of small-scale assays with a 96-well plate in C. elegans. In general, a fluorimetric assay is superior in sensitivity to a colorimetric assay; however, the colorimetric approach is more suitable for the use in common laboratories. Another important issue in these assays for quantitative determination is protein precipitation of homogenized C. elegans samples. In our protein precipitation method, common precipitants (e.g., trichloroacetic acid, perchloric acid and metaphosphoric acid) are used for sample preparation. A protein-free assay sample is prepared by directly adding cold precipitant (final concentration of 5%) during homogenization.

A mutation in the SDHC gene of complex II increases oxidative stress, resulting in apoptosis and tumorigenesis.

Intracellular oxidative stress from mitochondria is thought to be important in carcinogenesis and tumorigenesis, but direct experimental proof is limited. In this study, a transgenic mouse cell line (SDHC E69) with a mutated SDHC gene (a subunit of complex II in the electron transport chain) was constructed to test this question. The SDHC E69 cells overproduced superoxide anion (O(2)(-)) from mitochondria, had elevated cytoplasmic carbonyl proteins and 8-OH-deoxyguanine in their DNA as well as significantly higher mutation frequencies than wild type. There were many apoptotic cells in this cell line, as predicted by the observed increase in caspase 3 activity, decrease in mitochondrial membrane potential, and structural changes in their mitochondria. In addition, some cells that escaped from apoptosis underwent transformation, as evidenced by the fact that SDHC E69 cells caused benign tumors when injected under the epithelium of nude mice. These results underscore the notion that mitochondrially generated oxidative stress can contribute to nuclear DNA damage, mutagenesis, and ultimately, tumorigenesis.

Endogenous reactive oxygen species cause astrocyte defects and neuronal dysfunctions in the hippocampus: a new model for aging brain.

The etiology of astrocyte dysfunction is not well understood even though neuronal defects have been extensively studied in a variety of neuronal degenerative diseases. Astrocyte defects could be triggered by the oxidative stress that occurs during physiological aging. Here, we provide evidence that intracellular or mitochondrial reactive oxygen species (ROS) at physiological levels can cause hippocampal (neuronal) dysfunctions. Specifically, we demonstrate that astrocyte defects occur in the hippocampal area of middle-aged Tet-mev-1 mice with the SDHCV69E mutation. These mice are characterized by chronic oxidative stress. Even though both young adult and middle-aged Tet-mev-1 mice overproduced MitoSOX Red-detectable mitochondrial ROS compared to age-matched wild-type C57BL/6J mice, only young adult Tet-mev-1 mice upregulated manganese and copper/zinc superoxide dismutase (Mn- and Cu/Zn-SODs) activities to eliminate the MitoSOX Red-detectable mitochondrial ROS. In contrast, middle-aged Tet-mev-1 mice accumulated both MitoSOX Red-detectable mitochondrial ROS and CM-H2 DCFDA-detectable intracellular ROS. These ROS levels appeared to be in the physiological range as shown by normal thiol and glutathione disulfide/glutathione concentrations in both young adult and middle-aged Tet-mev-1 mice relative to age-matched wild-type C57BL/6J mice. Furthermore, only middle-aged Tet-mev-1 mice showed JNK/SAPK activation and Ca2+ overload, particularly in astrocytes. This led to decreasing levels of glial fibrillary acidic protein and S100ß in the hippocampal area. Significantly, there were no pathological features such as apoptosis, amyloidosis, and lactic acidosis in neurons and astrocytes. Our findings suggest that the age-dependent physiologically relevant chronic oxidative stress caused astrocyte defects in mice with impaired mitochondrial electron transport chain functionality.