Oxidative damage and mitochondrial decay in aging

Reactive oxygen species in the pathogenesis of sarcopenia

One of the most critical factors impacting healthspan in the elderly is the loss of muscle mass and function, clinically referred to as sarcopenia. Muscle atrophy and weakness lead to loss of mobility, increased risk of injury, metabolic changes and loss of independence. Thus, defining the underlying mechanisms of sarcopenia is imperative to enable the development of effective interventions to preserve muscle function and quality in the elderly and improve healthspan. Over the past few decades, understanding the roles of mitochondrial dysfunction and oxidative stress has been a major focus of studies seeking to reveal critical molecular pathways impacted during aging. In this review, we will highlight how oxidative stress might contribute to sarcopenia by discussing the impact of oxidative stress on the loss of innervation and alteration in the neuromuscular junction (NMJ), on muscle mitochondrial function and atrophy pathways, and finally on muscle contractile function.

Too old for healthy aging? Exploring age limits of longevity treatments

It is well documented that aging elicits metabolic failures, while poor metabolism contributes to accelerated aging. Metabolism in general, and energy metabolism in particular are also effective entry points for interventions that extend lifespan and improve organ function during aging. In this review, we discuss common metabolic remedies for healthy aging from the angle of their potential age-specificity. We demonstrate that some well-known metabolic treatments are mostly effective in young and middle-aged organisms, while others maintain high efficacy independently of age. The mechanistic basis of presence or lack of the age limitations is laid out and discussed.

Spermidine Enhances Mitochondrial Bioenergetics in Young and Aged Human-Induced Pluripotent Stem Cell-Derived Neurons

The accumulation of damaged mitochondria has long been considered a hallmark of the aging process. Among various factors, age-related mitochondrial alterations comprise bioenergetic impairments and disturbances in reactive oxygen species (ROS) control, thereby negatively affecting mitochondrial performance and ultimately accelerating aging. Previous studies have revealed that polyamine spermidine appears to exert health-protective and lifespan-promoting effects. Notably, recent findings have also described a spermidine-induced improvement in age-associated mitochondrial dysfunction, but the beneficial effects of spermidine on aged mitochondria have not been entirely examined yet. Here, we show that spermidine positively regulates several parameters related to mitochondrial bioenergetics and mitochondrial redox homeostasis in young and aged human-induced pluripotent stem cell-derived neurons. We report that spermidine treatment increases adenosine triphosphate production and mitochondrial membrane potential, which is accompanied by an attenuation in mitochondrial ROS levels in both age groups. Furthermore, we demonstrate a spermidine-mediated amelioration in mitochondrial respiration in both young and aged neurons. Overall, our findings suggest that nutritional spermidine supplementation might represent an attractive therapeutic approach to enhance mitochondrial function, consequently decelerating aging.

O-GlcNAc participates in the meiosis of aging oocytes by mediating mitochondrial function

In brief

O-GlcNAc plays an important role in many age-related diseases. This study shows that O-GlcNAc participates in oocyte aging and that reducing O-GlcNAc levels in aging oocytes improves oocyte quality.

Abstract

With an increase in the mean age at parturition worldwide, female reproductive aging has become a key health problem. Advanced maternal age is reflected by decreased oocyte quality; however, the molecular mechanisms of oocyte aging are uncharacterized. O-linked N-acetylglucosamine (O-GlcNAc), a dynamic posttranslational modification, plays a critical role in the development of many age-related diseases; yet, it remains unclear whether and how O-GlcNAc participates in oocyte aging. Here, we found that global O-GlcNAc was elevated in normal biological aging mice oocytes (9 months), which were characterized by meiotic maturation failure and impaired mitochondrial function. Specifically, O-GlcNAc targeted the mitochondrial fission protein dynamic-related protein 1 to mediate mitochondrial distribution in the process of aging. Using the O-GlcNAcase (OGA) pharmacological inhibitor Thiamet-G and Oga knockdown (Oga-KD) to mimic the age-related high O-GlcNAc in young oocytes from 6-8 week-old mice mimicked the phenotype of oocyte aging. Moreover, reducing O-GlcNAc levels in aging oocytes restored spindle organization to improve oocyte quality. Our results demonstrate that O-GlcNAc is a key regulator of meiotic maturation that participates in the progression of oocyte aging.

Similarities in B Cell Defects between Aging and Obesity

The aging population is increasing worldwide, and there is also an increase in the aging population living with overweight and obesity, due to changes in lifestyle and in dietary patterns that elderly individuals experience later in life. Both aging and obesity are conditions of accelerated metabolic dysfunction and dysregulated immune responses. In this review, we summarize published findings showing that obesity induces changes in humoral immunity similar to those induced by aging and that the age-associated B cell defects are mainly due to metabolic changes. We discuss the role of the obese adipose tissue in inducing dysfunctional humoral responses and autoimmune Ab secretion.

Gene therapy for fat-1 prevents obesity-induced metabolic dysfunction, cellular senescence, and osteoarthritis

Obesity is one of the primary risk factors for osteoarthritis (OA), acting through cross talk among altered biomechanics, metabolism, adipokines, and dietary free fatty acid (FA) composition. Obesity and aging have been linked to cellular senescence in various tissues, resulting in increased local and systemic inflammation and immune dysfunction. We hypothesized that obesity and joint injury lead to cellular senescence that is typically associated with increased OA severity or with aging and that the ratio of omega-6 (ω-6) to omega-3 (ω-3) FAs regulates these pathologic effects. Mice were placed on an ω-6-rich high-fat diet or a lean control diet and underwent destabilization of the medial meniscus to induce OA. Obesity and joint injury significantly increased cellular senescence in subcutaneous and visceral fat as well as joint tissues such as synovium and cartilage. Using adeno-associated virus (AAV) gene therapy for fat-1, a fatty acid desaturase that converts ω-6 to ω-3 FAs, decreasing the serum ω-6:ω-3 FA ratio had a strong senomorphic and therapeutic effect, mitigating metabolic dysfunction, cellular senescence, and joint degeneration. In vitro coculture of bone marrow-derived macrophages and chondrocytes from control and AAV8-fat1-treated mice were used to examine the roles of various FA mediators in regulating chondrocyte senescence. Our results suggest that obesity and joint injury result in a premature "aging" of the joint as measured by senescence markers, and these changes can be ameliorated by altering FA composition using fat-1 gene therapy. These findings support the potential for fat-1 gene therapy to treat obesity- and/or injury-induced OA clinically.

Intraspecific diversity of Myrmecophilus acervorum (Orthoptera: Myrmecophilidae) indicating an ongoing cryptic speciation

Myrmecophilus acervorum, previously considered a parthenogenetic species widely-distributed in Europe, has been observed to have both sexes in populations inhabiting the central part of the distribution range. Specimens from those heterosexual populations have been found being infected with Wolbachia. New mitochondrial data (COI and 16S markers) revealed the well-supported differentiation of M. acervorum populations inhabiting western Polesie (Poland) and southern Europe. In turn, analyses of EF1α marker support the hypothesis on the unfinished lineage sorting at the nuclear DNA level. Interestingly, we found that parthenogenetic populations inhabiting western Polesie are infected with Wolbachia belonging to supergroup A, while endosymbionts occurring in sexual populations of M. acervorum observed in Romania belong to supergroup B. Furthermore, new and potentially diagnostic characteristics in the external structures of the eyes of M. acervorum were identified. The surface of ommatidia in specimens occurring in southern Europe was smooth. In contrast, the ommatidia surface of individuals collected in Poland was visibly sculptured. To sum up, the significant genetic variability found in the present case, and the differentiating morphological character, are almost certainly effects of cryptic species being present within M. acervorum. This is indicative of ongoing speciation within the populations of this insect, and of simultaneous unfinished lineage sorting at the nuclear DNA level.

The Role of Molecular and Cellular Aging Pathways on Age-Related Hearing Loss

Aging, a complex process marked by molecular and cellular changes, inevitably influences tissue and organ homeostasis and leads to an increased onset or progression of many chronic diseases and conditions, one of which is age-related hearing loss (ARHL). ARHL, known as presbycusis, is characterized by the gradual and irreversible decline in auditory sensitivity, accompanied by the loss of auditory sensory cells and neurons, and the decline in auditory processing abilities associated with aging. The extended human lifespan achieved by modern medicine simultaneously exposes a rising prevalence of age-related conditions, with ARHL being one of the most significant. While our understanding of the molecular basis for aging has increased over the past three decades, a further understanding of the interrelationship between the key pathways controlling the aging process and the development of ARHL is needed to identify novel targets for the treatment of AHRL. The dysregulation of molecular pathways (AMPK, mTOR, insulin/IGF-1, and sirtuins) and cellular pathways (senescence, autophagy, and oxidative stress) have been shown to contribute to ARHL. However, the mechanistic basis for these pathways in the initiation and progression of ARHL needs to be clarified. Therefore, understanding how longevity pathways are associated with ARHL will directly influence the development of therapeutic strategies to treat or prevent ARHL. This review explores our current understanding of the molecular and cellular mechanisms of aging and hearing loss and their potential to provide new approaches for early diagnosis, prevention, and treatment of ARHL.

Mitochondrial homeostasis in odontoblast: Physiology, pathogenesis and targeting strategies

Caries and pulpitis remain a major global disease burden and affect the quality of life of patients. Odontoblasts are key players in the progression of caries and pulpitis, not only secreting and mineralizing to form dentin, but also acting as a wall of defense to initiate immune defenses. Mitochondrion is an information processor for numerous cellular activities, and dysregulation of mitochondrion homeostasis not only affects cellular metabolism but also triggers a wide range of diseases. Elucidating mitochondrial homeostasis in odontoblasts can help deepen scholars' understanding of odontoblast-associated diseases. Articles on mitochondrial homeostasis in odontoblasts were evaluated for information pertinent to include in this narrative review. This narrative review focused on understanding the complex interplay between mitochondrial homeostasis in odontoblasts under physiological and pathological conditions. Furthermore, mitochondria-centered therapeutic strategies (including mitochondrial base editing, targeting platforms, and mitochondrial transplantation) were emphasized by resolving key genes that regulate mitochondrial function. Mitochondria are involved in odontoblast differentiation and function, and act as mitochondrial danger-associated molecular patterns (mtDAMPs) to mediate odontoblast pathological progression. Novel mitochondria-centered therapeutic strategies are particularly attractive as emerging therapeutic approaches for the maintenance of mitochondrial homeostasis. It is expected to probe key events of odontoblast differentiation and advance the clinical resolution of dentin formation and mineralization disorders and odontoblast-related diseases.

The effects of light emitting diodes on mitochondrial function and cellular viability of M-1 cell and mouse CD1 brain cortex neurons

The invention of Light Emitting Diode (LED) revolutionized energy-efficient illumination, but concerns persist regarding the potential harm of blue light to our eyes. In this study, we scrutinized the impact of LED light characteristics on eyes using two cell types: M-1 (rich in mitochondria) and CD-1 (neuronal). Variations in color rendering index (CRI) and correlated color temperature (CCT) were investigated, alongside exposure durations ranging from 0 to 24 hours. The findings illuminated the potential benefits of high-quality LED lighting, characterized by a high CRI and low CCT, which emits a greater proportion of red light. This form of lighting was associated with enhanced cell proliferation, elevated ATP levels, and reduced oxidative stress. In contrast, LEDs with low CRI and high CCT exhibited adverse effects, diminishing cell viability and increasing oxidative stress. These results suggest that high-quality LED lighting may have neuroprotective potential as a treatment option, such as for retinal ganglion cells.

Immunometabolic Regulation of Vaccine-Induced Antibody Responses in Aging Mice

Immune cells undergo metabolic reprogramming to meet the demands associated with immune responses. The effects of aging on these pathways and on the metabolic phenotype of the immune cells participating in antibody responses to vaccines are still largely unknown. Here we used a vaccine for SARS-CoV-2 that utilizes the cellular heat shock chaperone glycoprotein 96 (gp96), engineered to co-express SARS-CoV-2 Spike (spike) protein (gp96-Ig-S). Results show that this vaccine induces comparable B cell primary responses in young and old mice at later time points, but a significantly lesser secondary response in old as compared to young mice, with the antibodies generated in the secondary response being also of lower avidity. This occurs because aging changes the B cell metabolic phenotype and induces hyper-metabolic B cells that are associated with higher intrinsic inflammation and decreased protective antibody responses. However, the gp96-Ig-S vaccine was found to be effective in significantly reducing the metabolic/inflammatory status of B cells from old mice, suggesting the possibility that targeting metabolic pathways may improve immune function in old mice that do not respond adequately to the vaccine.

Aberrant mitochondrial DNA synthesis in macrophages exacerbates inflammation and atherosclerosis

There is a large body of evidence that cellular metabolism governs inflammation, and that inflammation contributes to the progression of atherosclerosis. However, whether mitochondrial DNA synthesis affects macrophage function and atherosclerosis pathology is not fully understood. Here we show, by transcriptomic analyzes of plaque macrophages, spatial single cell transcriptomics of atherosclerotic plaques, and functional experiments, that mitochondrial DNA (mtDNA) synthesis in atherosclerotic plaque macrophages are triggered by vascular cell adhesion molecule 1 (VCAM-1) under inflammatory conditions in both humans and mice. Mechanistically, VCAM-1 activates C/EBPα, which binds to the promoters of key mitochondrial biogenesis genes - Cmpk2 and Pgc1a. Increased CMPK2 and PGC-1α expression triggers mtDNA synthesis, which activates STING-mediated inflammation. Consistently, atherosclerosis and inflammation are less severe in Apoe-/- mice lacking Vcam1 in macrophages. Downregulation of macrophage-specific VCAM-1 in vivo leads to decreased expression of LYZ1 and FCOR, involved in STING signalling. Finally, VCAM-1 expression in human carotid plaque macrophages correlates with necrotic core area, mitochondrial volume, and oxidative damage to DNA. Collectively, our study highlights the importance of macrophage VCAM-1 in inflammation and atherogenesis pathology and proposes a self-acerbating pathway involving increased mtDNA synthesis.

Constitutive, Muscle-Specific Orai1 Knockout Results in the Incomplete Assembly of Ca2+ Entry Units and a Reduction in the Age-Dependent Formation of Tubular Aggregates

Store-operated Ca2+ entry (SOCE) is a ubiquitous cellular mechanism that cells use to activate extracellular Ca2+ entry when intracellular Ca2+ stores are depleted. In skeletal muscle, SOCE occurs within Ca2+ entry units (CEUs), intracellular junctions between stacks of SR membranes containing STIM1 and transverse tubules (TTs) containing ORAI1. Gain-of-function mutations in STIM1 and ORAI1 are linked to tubular aggregate (TA) myopathy, a disease characterized by the atypical accumulation of tubes of SR origin. Moreover, SOCE and TAs are increased in the muscles of aged male mice. Here, we assessed the longitudinal effects (from 4-6 months to 10-14 months of age) of constitutive, muscle-specific Orai1 knockout (cOrai1 KO) on skeletal muscle structure, function, and the assembly of TAs and CEUs. The results from these studies indicate that cOrai1 KO mice exhibit a shorter lifespan, reduced body weight, exercise intolerance, decreased muscle-specific force and rate of force production, and an increased number of structurally damaged mitochondria. In addition, electron microscopy analyses revealed (i) the absence of TAs with increasing age and (ii) an increased number of SR stacks without adjacent TTs (i.e., incomplete CEUs) in cOrai1 KO mice. The absence of TAs is consistent with TAs being formed as a result of excessive ORAI1-dependent Ca2+ entry.

Mitochondrial dysfunction and its association with age-related disorders

Aging is a complex process that features a functional decline in many organelles. Various factors influence the aging process, such as chromosomal abnormalities, epigenetic changes, telomere shortening, oxidative stress, and mitochondrial dysfunction. Mitochondrial dysfunction significantly impacts aging because mitochondria regulate cellular energy, oxidative balance, and calcium levels. Mitochondrial integrity is maintained by mitophagy, which helps maintain cellular homeostasis, prevents ROS production, and protects against mtDNA damage. However, increased calcium uptake and oxidative stress can disrupt mitochondrial membrane potential and permeability, leading to the apoptotic cascade. This disruption causes increased production of free radicals, leading to oxidative modification and accumulation of mitochondrial DNA mutations, which contribute to cellular dysfunction and aging. Mitochondrial dysfunction, resulting from structural and functional changes, is linked to age-related degenerative diseases. This review focuses on mitochondrial dysfunction, its implications in aging and age-related disorders, and potential anti-aging strategies through targeting mitochondrial dysfunction.

USP7 promotes cardiometabolic disorders and mitochondrial homeostasis dysfunction in diabetic mice via stabilizing PGC1β

Diabetic cardiomyopathy (DCM) is a major complication of diabetes and is characterized by left ventricular dysfunction. Currently, there is a lack of effective treatments for DCM. Ubiquitin-specific protease 7 (USP7) plays a key role in various diseases. However, whether USP7 is involved in DCM has not been established. In this study, we demonstrated that USP7 was upregulated in diabetic mouse hearts and NMCMs co-treated with HG+PA or H9c2 cells treated with PA. Abnormalities in diabetic heart morphology and function were reversed by USP7 silencing through conditional gene knockout or chemical inhibition. Proteomic analysis coupled with biochemical validation confirmed that PCG1β was one of the direct protein substrates of USP7 and aggravated myocardial damage through coactivation of the PPARα signaling pathway. USP7 silencing restored the expression of fatty acid metabolism-related proteins and restored mitochondrial homeostasis by inhibiting mitochondrial fission and promoting fusion events. Similar effects were also observed in vitro. Our data demonstrated that USP7 promoted cardiometabolic metabolism disorders and mitochondrial homeostasis dysfunction via stabilizing PCG1β and suggested that silencing USP7 may be a therapeutic strategy for DCM.

Decreasing Intracellular Entropy by Increasing Mitochondrial Efficiency and Reducing ROS Formation-The Effect on the Ageing Process and Age-Related Damage

A hypothesis is presented to explain how the ageing process might be influenced by optimizing mitochondrial efficiency to reduce intracellular entropy. Research-based quantifications of entropy are scarce. Non-equilibrium metabolic reactions and compartmentalization were found to contribute most to lowering entropy in the cells. Like the cells, mitochondria are thermodynamically open systems exchanging matter and energy with their surroundings-the rest of the cell. Based on the calculations from cancer cells, glycolysis was reported to produce less entropy than mitochondrial oxidative phosphorylation. However, these estimations depended on the CO2 concentration so that at slightly increased CO2, it was oxidative phosphorylation that produced less entropy. Also, the thermodynamic efficiency of mitochondrial respiratory complexes varies depending on the respiratory state and oxidant/antioxidant balance. Therefore, in spite of long-standing theoretical and practical efforts, more measurements, also in isolated mitochondria, with intact and suboptimal respiration, are needed to resolve the issue. Entropy increases in ageing while mitochondrial efficiency of energy conversion, quality control, and turnover mechanisms deteriorate. Optimally functioning mitochondria are necessary to meet energy demands for cellular defence and repair processes to attenuate ageing. The intuitive approach of simply supplying more metabolic fuels (more nutrients) often has the opposite effect, namely a decrease in energy production in the case of nutrient overload. Excessive nutrient intake and obesity accelerate ageing, while calorie restriction without malnutrition can prolong life. Balanced nutrient intake adapted to needs/activity-based high ATP requirement increases mitochondrial respiratory efficiency and leads to multiple alterations in gene expression and metabolic adaptations. Therefore, rather than overfeeding, it is necessary to fine-tune energy production by optimizing mitochondrial function and reducing oxidative stress; the evidence is discussed in this paper.

Associations between regional adipose tissue distribution and skeletal muscle bioenergetics in older men and women

OBJECTIVE

The aim of this study was to examine associations of ectopic adipose tissue (AT) with skeletal muscle (SM) mitochondrial bioenergetics in older adults.

METHODS

Cross-sectional data from 829 adults ≥70 years of age were used. Abdominal, subcutaneous, and visceral AT and thigh muscle fat infiltration (MFI) were quantified by magnetic resonance imaging. SM mitochondrial energetics were characterized in vivo (31P-magnetic resonance spectroscopy; ATPmax) and ex vivo (high-resolution respirometry maximal oxidative phosphorylation [OXPHOS]). ActivPal was used to measure physical activity ([PA]; step count). Linear regression adjusted for covariates was applied, with sequential adjustment for BMI and PA.

RESULTS

Independent of BMI, total abdominal AT (standardized [Std.] β = -0.21; R2 = 0.09) and visceral AT (Std. β = -0.16; R2 = 0.09) were associated with ATPmax (p < 0.01; n = 770) but not following adjustment for PA (p ≥ 0.05; n = 658). Visceral AT (Std. β = -0.16; R2 = 0.25) and thigh MFI (Std. β = -0.11; R2 = 0.24) were associated with carbohydrate-supported maximal OXPHOS independent of BMI and PA (p < 0.05; n = 609). Total abdominal AT (Std. β = -0.19; R2 = 0.24) and visceral AT (Std. β = -0.17; R2 = 0.24) were associated with fatty acid-supported maximal OXPHOS independent of BMI and PA (p < 0.05; n = 447).

CONCLUSIONS

Skeletal MFI and abdominal visceral, but not subcutaneous, AT are inversely associated with SM mitochondrial bioenergetics in older adults independent of BMI. Associations between ectopic AT and in vivo mitochondrial bioenergetics are attenuated by PA.

Mitochondrial dysfunction: mechanisms and advances in therapy

Mitochondria, with their intricate networks of functions and information processing, are pivotal in both health regulation and disease progression. Particularly, mitochondrial dysfunctions are identified in many common pathologies, including cardiovascular diseases, neurodegeneration, metabolic syndrome, and cancer. However, the multifaceted nature and elusive phenotypic threshold of mitochondrial dysfunction complicate our understanding of their contributions to diseases. Nonetheless, these complexities do not prevent mitochondria from being among the most important therapeutic targets. In recent years, strategies targeting mitochondrial dysfunction have continuously emerged and transitioned to clinical trials. Advanced intervention such as using healthy mitochondria to replenish or replace damaged mitochondria, has shown promise in preclinical trials of various diseases. Mitochondrial components, including mtDNA, mitochondria-located microRNA, and associated proteins can be potential therapeutic agents to augment mitochondrial function in immunometabolic diseases and tissue injuries. Here, we review current knowledge of mitochondrial pathophysiology in concrete examples of common diseases. We also summarize current strategies to treat mitochondrial dysfunction from the perspective of dietary supplements and targeted therapies, as well as the clinical translational situation of related pharmacology agents. Finally, this review discusses the innovations and potential applications of mitochondrial transplantation as an advanced and promising treatment.

GGT5: a potential immunotherapy response inhibitor in gastric cancer by modulating GSH metabolism and sustaining memory CD8+ T cell infiltration

PURPOSE

The variable responses to immunotherapy observed in gastric cancer (GC) patients can be attributed to the intricate nature of the tumor microenvironment. Glutathione (GSH) metabolism significantly influences the initiation and progression of gastric cancer. Consequently, targeting GSH metabolism holds promise for improving the effectiveness of Immune checkpoints inhibitors (ICIs).

METHODS

We investigated 16 genes related to GSH metabolism, sourced from the MSigDB database, using pan-cancer datasets from TCGA. The most representative prognosis-related gene was identified for further analysis. ScRNA-sequencing analysis was used to explore the tumor heterogeneity of GC, and the results were confirmed by  Multiplex immunohistochemistry (mIHC).

RESULTS

Through DEGs, LASSO, univariate and multivariate Cox regression analyses, and survival analysis, we identified GGT5 as the hub gene in GSH metabolism with the potential to promote GC. Combining CIBERSORT, ssGSEA, and scRNA analysis, we constructed the immune architecture of GC. The subpopulations of T cells were isolated, revealing a strong association between GGT5 and memory CD8+ T cells. Furthermore, specimens from 10 GC patients receiving immunotherapy were collected. mIHC was used to assess the expression levels of GGT5 and memory CD8+ T cell markers. Our results established a positive correlation between GGT5 expression, the enrichment of memory CD8+ T cells, and a suboptimal response to immunotherapy.

CONCLUSIONS

Our study identifies GGT5, a hub gene in GSH metabolism, as a potential therapeutic target for inhibiting the response to immunotherapy in GC patients. These findings offer new insights into strategies for optimizing immunotherapy of GC.

Single-cell mtDNA dynamics in tumors is driven by coregulation of nuclear and mitochondrial genomes

The extent of cell-to-cell variation in tumor mitochondrial DNA (mtDNA) copy number and genotype, and the phenotypic and evolutionary consequences of such variation, are poorly characterized. Here we use amplification-free single-cell whole-genome sequencing (Direct Library Prep (DLP+)) to simultaneously assay mtDNA copy number and nuclear DNA (nuDNA) in 72,275 single cells derived from immortalized cell lines, patient-derived xenografts and primary human tumors. Cells typically contained thousands of mtDNA copies, but variation in mtDNA copy number was extensive and strongly associated with cell size. Pervasive whole-genome doubling events in nuDNA associated with stoichiometrically balanced adaptations in mtDNA copy number, implying that mtDNA-to-nuDNA ratio, rather than mtDNA copy number itself, mediated downstream phenotypes. Finally, multimodal analysis of DLP+ and single-cell RNA sequencing identified both somatic loss-of-function and germline noncoding variants in mtDNA linked to heteroplasmy-dependent changes in mtDNA copy number and mitochondrial transcription, revealing phenotypic adaptations to disrupted nuclear/mitochondrial balance.

Radiocarbon Flux Measurements Provide Insight into Why a Pyroligneous Acid Product Stimulates Plant Growth

Agriculture in the 21st century faces many formidable challenges with the growing global population. Increasing demands on the planet's natural resources already tax existing agricultural practices. Today, many farmers are using biochemical treatments to improve their yields. Commercialized organic biostimulants exist in the form of pyroligneous acid generated by burning agricultural waste products. Recently, we examined the mechanisms through which a commercial pyroligneous acid product, Coriphol™, manufactured by Corigin Solutions, Inc., stimulates plant growth. During the 2023 growing season, outdoor studies were conducted in soybean to examine the effects of different Coriphol™ treatment concentrations on plant growth. Plant height, number of leaves, and leaf size were positively impacted in a dose-dependent manner with 2 gallon/acre soil treatments being optimal. At harvest, this level of treatment boosted crop yield by 40%. To gain an understanding of why Coriphol™ improves plant fitness, follow-up laboratory-based studies were conducted using radiocarbon flux analysis. Here, radioactive 11CO2 was administered to live plants and comparisons were made between untreated soybean plants and plants treated at an equivalent Coriphol™ dose of 2 gallons/acre. Leaf metabolites were analyzed using radio-high-performance liquid chromatography for [11C]-chlorophyll (Chl) a and b components, as well as [11C]-β-carotene (β-Car) where fractional yields were used to calculate metabolic rates of synthesis. Altogether, Coriphol™ treatment boosted rates of Chl a, Chl b, and β-Car biosynthesis 3-fold, 2.6-fold, and 4.7-fold, respectively, and also increased their metabolic turnover 2.2-fold, 2.1-fold, and 3.9-fold, respectively. Also, the Chl a/b ratio increased from 3.1 to 3.4 with treatment. Altogether, these effects contributed to a 13.8% increase in leaf carbon capture.

Does diet influence aging? Evidence from animal studies

Nutrition profoundly influences the risk for many age-related diseases. Whether nutrition influences human aging biology directly is less clear. Studies in different animal species indicate that reducing food intake ("caloric restriction" [CR]) can increase lifespan and delay the onset of diseases and the biological hallmarks of aging. Obesity has been described as "accelerated aging" and therefore the lifespan and health benefits generated by CR in both aging and obesity may occur via similar mechanisms. Beyond calorie intake, studies based on nutritional geometry have shown that protein intake and the interaction between dietary protein and carbohydrates influence age-related health and lifespan. Studies where animals are calorically restricted by providing free access to diluted diets have had less impact on lifespan than those studies where animals are given a reduced aliquot of food each day and are fasting between meals. This has drawn attention to the role of fasting in health and aging, and exploration of the health effects of various fasting regimes. Although definitive human clinical trials of nutrition and aging would need to be unfeasibly long and unrealistically controlled, there is good evidence from animal experiments that some nutritional interventions based on CR, manipulating dietary macronutrients, and fasting can influence aging biology and lifespan.

Multisession anodal epidural direct current stimulation of the auditory cortex delays the progression of presbycusis in the Wistar rat

Presbycusis or age-related hearing loss (ARHL) is one of the most prevalent chronic health problems facing aging populations. Along the auditory pathway, the stations involved in transmission and processing, function as a system of interconnected feedback loops. Regulating hierarchically auditory processing, auditory cortex (AC) neuromodulation can, accordingly, activate both peripheral and central plasticity after hearing loss. However, previous ARHL-prevention interventions have mainly focused on preserving the structural and functional integrity of the inner ear, overlooking the central auditory system. In this study, using an animal model of spontaneous ARHL, we aim at assessing the effects of multisession epidural direct current stimulation of the AC through stereotaxic implantation of a 1-mm silver ball anode in Wistar rats. Consisting of 7 sessions (0.1 mA/10 min), on alternate days, in awake animals, our stimulation protocol was applied at the onset of hearing loss (threshold shift detection at 16 months). Click- and pure-tone auditory brainstem responses (ABRs) were analyzed in two animal groups, namely electrically stimulated (ES) and non-stimulated (NES) sham controls, comparing recordings at 18 months of age. At 18 months, NES animals showed significantly increased threshold shifts, decreased wave amplitudes, and increased wave latencies after click and tonal ABRs, reflecting a significant, spontaneous ARHL evolution. Conversely, in ES animals, no significant differences were detected in any of these parameters when comparing 16 and 18 months ABRs, indicating a delay in ARHL progression. Electrode placement in the auditory cortex was accurate, and the stimulation did not cause significant damage, as shown by the limited presence of superficial reactive microglial cells after IBA1 immunostaining. In conclusion, multisession DC stimulation of the AC has a protective effect on auditory function, delaying the progression of presbycusis.

The Effects of Photobiomodulation on Knee Function, Pain, and Exercise Tolerance in Older Adults: A Meta-analysis of Randomized Controlled Trials

OBJECTIVE

To assess whether photobiomodulation therapy (PBMT) enhances the benefits of exercise in older adults.

DATA SOURCES

PubMed, Scopus, Medline, and Web of Science, dated to February 2023.

STUDY SELECTION

All included studies were randomized controlled trials of PBMT combined with exercise co-intervention in persons 60 years and older.

OUTCOME MEASURES

Western Ontario and McMaster University Osteoarthritis Index (WOMAC-total, pain, stiffness and function), perceived pain intensity, timed Up and Go (TUG) Test, 6-min walk test (6MWT), muscle strength, and knee range of motion were included.

DATA EXTRACTION

Two researchers independently performed data extraction. Article data were extracted in Excel and summarized by a third researcher.

DATA SYNTHESIS

The meta-analysis included 14 of the 1864 studies searched in the database. No statistical differences were found between the treatment and control groups in terms of WOMAC-stiffness (mean difference [MD]=-0.31, 95% confidence interval [CI] -0.64 to 0.03), TUG (MD=-0.17, 95% CI -0.71 to 0.38), 6MWT (MD=32.2, 95% CI -44.62 to 109.01), or muscle strength (standardized mean difference=0.24, 95% CI -0.02 to 0.50). However, statistically significant differences were found for WOMAC-total (MD=-6.83, 95% CI -12.3 to -1.37), WOMAC-pain (MD=-2.03, 95% CI -4.06 to -0.01), WOMAC-function (MD=-5.03, 95% CI -9.11 to -0.96), visual analog scale/numeric pain rating scale (MD=-1.24, 95% CI -2.43 to -0.06), and knee range of motion (MD=1.47, 95% CI 0.07 to 2.88).

CONCLUSIONS

In older adults who exercise regularly, PBMT can potentially provide additional pain relief, improve knee joint function, and increase knee joint range of motion.

Advanced Biological Applications of Cerium Oxide Nanozymes in Disease Related to Oxidative Damage

Due to their excellent catalytic activities, cerium oxide nanoparticles have promise as biological nanoenzymes. A redox reaction occurs between Ce3+ ions and Ce4+ ions during which they undergo conversion by acquiring or losing electrons as well as forming oxygen vacancies (or defects) in the lattice structure, which can act as antioxidant enzymes and simulate various enzyme activities. A number of cerium oxide nanoparticles have been engineered with multienzyme activities, including catalase, superoxide oxidase, peroxidase, and oxidase mimetic properties. Cerium oxide nanoparticles have nitric oxide radical clearing and radical scavenging properties and have been widely used in a number of fields of biology, including biomedicine, disease diagnosis, and treatment. This review provides a comprehensive introduction to the catalytic mechanisms and multiple enzyme activities of cerium oxide nanoparticles, along with their potential applications in the treatment of diseases of the brain, bones, nerves, and blood vessels.

Subcellular distribution of prohibitin 1 in rat liver during liver regeneration and its cellular implication

BACKGROUND

The function of prohibitin 1 (Phb1) during liver regeneration (LR) remains relatively unexplored. Our previous research identified downregulation of Phb1 in rat liver mitochondria 24 h after 70% partial hepatectomy (PHx), as determined by subcellular proteomic analysis.

AIM

To investigate the potential role of Phb1 during LR.

METHODS

We examined changes in Phb1 mRNA and protein levels, subcellular distribution, and abundance in rat liver during LR following 70% PHx. We also evaluated mitochondrial changes and apoptosis using electron microscopy and flow cytometry. RNA-interference-mediated knockdown of Phb1 (PHBi) was performed in BRL-3A cells.

RESULTS

Compared with sham-operation control groups, Phb1 mRNA and protein levels in 70% PHx test groups were downregulated at 24 h, then upregulated at 72 and 168 h. Phb1 was mainly located in mitochondria, showed a reduced abundance at 24 h, significantly increased at 72 h, and almost recovered to normal at 168 h. Phb1 was also present in nuclei, with continuous increase in abundance observed 72 and 168 h after 70% PHx. The altered ultrastructure and reduced mass of mitochondria during LR had almost completely recovered to normal at 168 h. PHBi in BRL-3A cells resulted in increased S-phase entry, a higher number of apoptotic cells, and disruption of mitochondrial membrane potential.

CONCLUSION

Phb1 may contribute to maintaining mitochondrial stability and could play a role in regulating cell proliferation and apoptosis of rat liver cells during LR.

Effects of resveratrol on in vitro circadian clock gene expression in young and older human adipose-derived progenitor cells

Observational studies in preclinical models demonstrate age-related declines in circadian functions. We hypothesized that age would be associated with declines in function of cell-autonomous circadian clocks in human tissue. Accordingly, we cultured adipose progenitor cells (APCs) from previously collected white-adipose tissue biopsies from abdominal subcutaneous depots of young (Age: 23.4 ± 2.1 yrs) vs. older female participants (Age: 70.6 ± 5.9 yrs). Using an in vitro model, we compared rhythmic gene expression profiles of core clock components, as an indicator of circadian oscillatory function. We observed consistent circadian rhythmicity of core clock components in young and older-APCs. Expression analysis showed increased levels of some components in older-APCs (CLOCK, CRY1, NR1D1) vs. young. We also investigated resveratrol (RSV), a well-known longevity-enhancing effector, for its effects on rhythmic clock gene expression profiles. We found that RSV resulted in gained rhythmicity of some components (CLOCK and CRY), loss of rhythmicity in others (PER2, CRY2), and altered some rhythmic parameters (NR1D1 and NR1D2), consistent in young and older-APCs. The observation of detectable circadian rhythmicity retained in vitro suggests that the oscillatory function of the cell-autonomous core clock in APCs is preserved at this stage of the aging process. RSV impacts core clock gene expression in APCs, implicating its potential as a therapeutic agent for longevity by targeting the core clock.

Effect of dietary antioxidants on free radical damage in dogs and cats

Alpha-tocopherol (vitamin E) is an antioxidant that is largely involved in immune defense and enhancing the ability of biological systems to respond to oxidative stress. During the process of free radical scavenging, vitamin C supports the regeneration of vitamin E. Although the functions of antioxidants and their importance have been widely studied, the intricate interplay between antioxidants has yet to be fully elucidated, especially in dogs and cats. As such, the objective of the present study was to determine the effect of a combination of dietary antioxidants on DNA damage and antioxidant status in dogs and cats. Forty adult mixed-breed dogs and 40 adult domestic shorthair cats were randomly assigned to one of four treatment groups per species. Dogs and cats remained in these groups for the 84-d duration of the study. The food differed in antioxidant supplementation with the control food meeting all of the Association of American Feed Control Officials requirements for complete and balanced nutrition, including sufficient vitamin E to exceed the published minimum. The treatment diets were targeted to include either 500, 1,000, or 1,500 IU vitamin E/kg as well as 100 ppm of vitamin C and 1.5 ppm of β-carotene in the food. The effect of vitamin E supplementation level on serum vitamin E concentration, DNA damage, and total antioxidant power was evaluated. Feeding diets enriched with antioxidants resulted in an increased (P < 0.05) circulating vitamin E concentration, increased (P < 0.05) immune cell protection, reduced (P < 0.05) DNA damage in dogs, and an improved (P < 0.05) antioxidant status. Overall, these data demonstrated that feeding a dry kibble with an antioxidant blend inclusive of vitamin E, vitamin C, and β-carotene enhanced cell protection and improved antioxidant status in dogs and cats.

Behavior and Cognition of the Senior Cat and Its Interaction with Physical Disease

In cats, age-related pathologic condition and neurologic degeneration can produce changes in activity, vocalization, appearance, appetite, litter box use, sleep-wake cycle, personality, and cognitive ability. These changes can influence the relationship between owner and pet. Although cognitive dysfunction syndrome (CDS) can cause altered behavior later in life, other medical or behavioral causes may mimic these clinical signs or complicate diagnosis. Management and treatment of CDS can be accomplished through pharmacologic intervention, diet and nutritional supplementation, and environmental enrichment aimed at slowing the progression of the disease.

Accumulation of 8-oxodG within the human mitochondrial genome positively associates with transcription

Mitochondrial DNA (mtDNA) can be subject to internal and environmental stressors that lead to oxidatively generated damage and the formation of 8-oxo-7,8-dihydro-2'-deoxyguanine (8-oxodG). The accumulation of 8-oxodG has been linked to degenerative diseases and aging, as well as cancer. Despite the well-described implications of 8-oxodG in mtDNA for mitochondrial function, there have been no reports of mapping of 8-oxodG across the mitochondrial genome. To address this, we used OxiDIP-Seq and mapped 8-oxodG levels in the mitochondrial genome of human MCF10A cells. Our findings indicated that, under steady-state conditions, 8-oxodG is non-uniformly distributed along the mitochondrial genome, and that the longer non-coding region appeared to be more protected from 8-oxodG accumulation compared with the coding region. However, when the cells have been exposed to oxidative stress, 8-oxodG preferentially accumulated in the coding region which is highly transcribed as H1 transcript. Our data suggest that 8-oxodG accumulation in the mitochondrial genome is positively associated with mitochondrial transcription.

ALKBH5-mediated CHAC1 depletion promotes malignant progression and decreases cisplatin-induced oxidative stress in gastric cancer

The m6a demethyltransferase ALKBH5 dynamically modulates gene expression and intracellular metabolic molecules by modifying RNA m6a in cancer cells. However, ALKBH5's function in gastric cancer (GC) has remained controversial. This study demonstrates that ALKBH5 is highly expressed in GC. Silencing ALKBH5 hampers proliferation, and metastatic potential, and induces cell death in GC cells. Through a comprehensive analysis of the transcriptome and m6A sequencing, alterations in certain ALKBH5 target genes, including CHAC1, were identified. ALKBH5's demethylation effect regulates CHAC1 RNA stability, leading to reduced CHAC1 expression. Moreover, CHAC1 modulates intracellular ROS levels, influencing the chemotherapy sensitivity of gastric cancer. In summary, our study unveils the pivotal role of the ALKBH5-CHAC1-ROS axis and highlights the significance of m6A methylation in gastric cancer.

Associations between regional adipose tissue distribution and skeletal muscle bioenergetics in older men and women

Objective

Examine the association of ectopic adipose tissue (AT) with skeletal muscle (SM) mitochondrial bioenergetics in older adults.

Methods

Cross-sectional data from 829 older adults ≥70 years was used. Total abdominal, subcutaneous, and visceral AT; and thigh muscle fat infiltration (MFI) was quantified by MRI. SM mitochondrial energetics were characterized using in vivo 31 P-MRS (ATP max ) and ex vivo high-resolution respirometry (maximal oxidative phosphorylation (OXPHOS)). ActivPal was used to measure PA (step count). Linear regression models adjusted for covariates were applied, with sequential adjustment for BMI and PA.

Results

Independent of BMI, total abdominal (standardized (Std.) β=-0.21; R 2 =0.09) and visceral AT (Std. β=-0.16; R 2 =0.09) were associated with ATP max ( p <0.01), but not after further adjustment for PA (p≥0.05). Visceral AT (Std. β=-0.16; R 2 =0.25) and thigh MFI (Std. β=-0.11; R 2 =0.24) were negatively associated with carbohydrate-supported maximal OXPHOS independent of BMI and PA ( p <0.05). Total abdominal AT (Std. β=-0.19; R 2 =0.24) and visceral AT (Std. β=-0.17; R 2 =0.24) were associated with fatty acid-supported maximal OXPHOS independent of BMI and PA (p<0.05).

Conclusions

Skeletal MFI and abdominal visceral, but not subcutaneous AT, are inversely associated with SM mitochondrial bioenergetics in older adults independent of BMI. Associations between ectopic AT and in vivo mitochondrial bioenergetics are attenuated by PA.

A Fenton Approach to Aromatic Radical Cations and Diarylmethane Synthesis

Manipulating carbon-centered radicals to add to electron-deficient systems is a well-precedented process. By coupling the Fe(II)-mediated Fenton reaction with the Fe(III)-mediated single-electron oxidation of anisolic compounds, we demonstrate how electron-rich carbon-centered radicals can react with electron-rich arenes through a radical-polar cascade pathway. This bioinspired approach produces diarylmethane derivatives from simple unfunctionalized precursors.

Resource allocation strategies for survival and reproduction by an invasive pest in response to intermittent fasting

Intermittent fasting (IF) is a type of dietary restriction that involves fasting periods in intervals, which has been used as a strategy to improve health and extend longevity. Regular fasting is common during the process of biological invasions in nature. Yet, it is not clear how invasive animals adjust their resource allocations to survival and reproduction when periodical starvation occurs. Here, we used Tetranychus ludeni, a haplodiploid spider mite and an important invasive pest of horticultural crops around the world, to investigate the effects of IF on its life history strategies. We show that IF increased the longevity in females but not in males probably because of differences in resource storage, metabolic rate, and mating cost between sexes. In response to IF, females traded off fecundity and egg size but not the number of daughters for longevity gain, suggesting that T. ludeni females can adjust their life history strategies for population survival and growth during invasion process. Eggs produced by fasted females realized the same hatch rate and resultant young had the same survival rate as those by unfasted ones. In addition, IF had transgenerational maternal effects which prolonged offspring development period. We suggest that the longer immature developmental period can increase the body size of resulting adults, compensating egg size loss for offspring fitness. Our findings provide insight into resource allocations as responses to fasting, knowledge of which can be used for evaluation of pest invasions and for management of animal survival and reproduction by dietary regulations.

The Evolution and Ecology of Oxidative and Antioxidant Status: A Comparative Approach in African Mole-Rats

The naked mole-rat of the family Bathyergidae has been the showpiece for ageing research as they contradict the traditional understanding of the oxidative stress theory of ageing. Some other bathyergids also possess increased lifespans, but there has been a remarkable lack of comparison between species within the family Bathyergidae. This study set out to investigate how plasma oxidative markers (total oxidant status (TOS), total antioxidant capacity (TAC), and the oxidative stress index (OSI)) differ between five species and three subspecies of bathyergids, differing in their maximum lifespan potential (MLSP), resting metabolic rate, aridity index (AI), and sociality. We also investigated how oxidative markers may differ between captive and wild-caught mole-rats. Our results reveal that increased TOS, TAC, and OSI are associated with increased MLSP. This pattern is more prevalent in the social-living species than the solitary-living species. We also found that oxidative variables decreased with an increasing AI and that wild-caught individuals typically have higher antioxidants. We speculate that the correlation between higher oxidative markers and MLSP is due to the hypoxia-tolerance of the mole-rats investigated. Hormesis (the biphasic response to oxidative stress promoting protection) is a likely mechanism behind the increased oxidative markers observed and promotes longevity in some members of the Bathyergidae family.

Rapid and ratiometric fluorescent detection of hypochlorite by glutathione functionalized molybdenum disulfide quantum dots

We proposed a rapid and ratiometric fluorescent detection method for hypochlorite by glutathione functionalized molybdenum disulfide quantum dots (G-MoS₂ QDs). The G-MoS₂ QDs were obtained through a hydrothermal method and the maximum fluorescence intensity was obtained at 430 nm under excitation of 360 nm. The fluorescence of G-MoS₂ QDs at 430 nm can be weakened by curcumin through the inner filter effect, meanwhile the fluorescence of curcumin at 540 nm appeared. Hypochlorite can fast oxidize curcumin and weaken the inner filter effect, thus the fluorescence of curcumin at 540 nm decreased and the fluorescence of G-MoS₂ QDs at 430 nm increased. This process takes only 30 s at room temperature. This is the rationale behind our rapid ratiometric fluorescent detection model for hypochlorite. Two linear detection ranges for hypochlorite are obtained with concentration from 1 to 20 μM and 20 to 30 μM, the limit of detection (LOD) was 11.5 nM. The standard spike recovery tests on milk and tap water samples showed satisfactory results, which extended the application of G-MoS₂ QDs in the field of ratiometric fluorescence detection assays.

Excitatory and inhibitory imbalances in the trisynaptic pathway in the hippocampus in schizophrenia: a postmortem ultrastructural study

BACKGROUND

A preponderance of evidence suggests that the hippocampus is a key region of dysfunction in schizophrenia. Neuroimaging and other studies indicate a relationship between hippocampal dysfunction and the degree of psychosis. Clinical data indicate hyperactivity in the hippocampus that precedes the onset of psychosis, and is correlated with symptom severity. In this study, we sought to identify circuitry at the electron microscopic level that could contribute to region-specific imbalances in excitation and inhibition in the hippocampus in schizophrenia. We used postmortem tissue from the anterior hippocampus from patients with schizophrenia and matched controls. Using stereological techniques, we counted and measured synapses, postsynaptic densities (PSDs), and evaluated size, number and optical density of mitochondria and parvalbumin-containing interneurons in key nodes of the trisynaptic pathway. Compared to controls, the schizophrenia group had decreased numbers of inhibitory synapses in CA3 and increased numbers of excitatory synapses in CA1; together, this indicates deficits in inhibition and an increase in excitation. The thickness of the PSD was larger in excitatory synapses in CA1, suggesting greater synaptic strength. In the schizophrenia group, there were fewer mitochondria in the dentate gyrus and a decrease in the optical density, a measure of functional integrity, in CA1. The number and optical density of parvalbumin interneurons were lower in CA3. The results suggest region-specific increases in excitatory circuitry, decreases in inhibitory neurotransmission and fewer or damaged mitochondria. These results are consistent with the hyperactivity observed in the hippocampus in schizophrenia in previous studies.

Elevated intracellular pH of zygotes during mouse aging causes mitochondrial dysfunction associated with poor embryo development

The mortality of preimplantation embryos is positively correlated with maternal age. However, the underlying mechanism for the poor quality of embryos remains unclear. Here, we found that aging caused elevated intracellular pH (pHi) in zygotes, which could trigger aberrant mitochondrial membrane potential, increased reactive oxygen species (ROS) levels, and poor embryo development. Moreover, single-cell transcriptome sequencing of mouse zygotes identified 120 genes that were significantly differentially expressed (DE) between young and older zygotes. These include genes such as Slc14a1, Fxyd5, CD74, and Bst, which are related to cell division, ion transporter, and cell differentiation. Further analysis indicated that these DE genes were enriched in apoptosis, the NF-kappa B signaling pathway, and the chemokine signaling pathway, which might be the key regulatory pathway affecting the quality of zygotes and subsequent embryo development. Taken together, our study helps elucidate the poor quality and development of older preimplantation embryos.

Mitochondria in cell senescence: A Friend or Foe?

Cell senescence denotes cell growth arrest in response to continuous replication or stresses damaging DNA or mitochondria. Mounting research suggests that cell senescence attributes to aging-associated failing organ function and diseases. Conversely, it participates in embryonic tissue maturation, wound healing, tissue regeneration, and tumor suppression. The acute or chronic properties and microenvironment may explain the double faces of senescence. Senescent cells display unique characteristics. In particular, its mitochondria become elongated with altered metabolomes and dynamics. Accordingly, mitochondria reform their function to produce more reactive oxygen species at the cost of low ATP production. Meanwhile, destructed mitochondrial unfolded protein responses further break the delicate proteostasis fostering mitochondrial dysfunction. Additionally, the release of mitochondrial damage-associated molecular patterns, mitochondrial Ca²⁺ overload, and altered NAD⁺ level intertwine other cellular organelle strengthening senescence. These findings further intrigue researchers to develop anti-senescence interventions. Applying mitochondrial-targeted antioxidants reduces cell senescence and mitigates aging by restoring mitochondrial function and attenuating oxidative stress. Metformin and caloric restriction also manifest senescent rescuing effects by increasing mitochondria efficiency and alleviating oxidative damage. On the other hand, Bcl2 family protein inhibitors eradicate senescent cells by inducing apoptosis to facilitate cancer chemotherapy. This review describes the different aspects of mitochondrial changes in senescence and highlights the recent progress of some anti-senescence strategies.

CHAC2 promotes lung adenocarcinoma by regulating ROS-mediated MAPK pathway activation

An imbalance in ROS (reactive oxidative species) and the antioxidant barrier regulates the process of tumorigenesis. GSH has a key effect in preventing cells from oxidative damage by scavenging ROS. The role of CHAC2, an enzyme regulating GSH, in lung adenocarcinoma remains unknown. Here, RNA sequencing data analysis and immunohistochemistry (IHC) assays of lung adenocarcinoma and normal lung tissues were used to verify the expression of CHAC2. The effect of CHAC2 on the proliferation abilities of lung adenocarcinoma cells was examined using a series of overexpression or knockout assays. RNA sequencing and IHC results showed that the expression level of CHAC2 in lung adenocarcinoma was higher than that in normal lung tissues. CCK-8, colony formation and subcutaneous xenograft experiments in BALB/c nude mice showed that in vitro and in vivo CHAC2 promoted the growth capacity of lung adenocarcinoma cells. Subsequent immunoblot, immunohistochemistry and flow cytometry experiments showed that CHAC2 increased ROS by reducing GSH in lung adenocarcinoma and that the elevated ROS activated the MAPK pathway. Our investigation identified a new role for CHAC2 and elucidated the mechanism by which CHAC2 promotes lung adenocarcinoma progression.

GFP-based red-emissive fluorescent probes for dual imaging of β-amyloid plaques and mitochondrial viscosity

Alzheimer's disease (AD), with incurable neurodegenerative damage, has attracted growing interest in exploration of better AD biomarkers in its early diagnosis. Among various biomarkers, amyloid-β (Aβ) aggregates and mitochondrial viscosity are closely related to AD and their dual imaging might provide a potential and feasible strategy. In this work, five GFP-based red-emissive fluorescent probes were rationally designed and synthesized for selective detection of β-amyloid plaques and viscosity, among which C25e exhibited superior properties and could successfully image β-amyloid plaques and mitochondrial viscosity with different fluorescence wavelength signals "turn-on" at around 624 and 640 nm, respectively. Moreover, the staining of brain sections from a transgenic AD mouse showed that probe C25e showed higher selectivity and signal-to-noise ratio towards Aβ plaques than commercially-available Thio-S. In addition, the probe C25e was, for the first time, employed for monitoring amyloid-β induced mitochondrial viscosity changes. Therefore, this GFP-based red-emissive fluorescent probe C25e could serve as a dual-functional tool for imaging β-amyloid plaques and mitochondrial viscosity, which might provide a unique strategy for the early diagnosis of Alzheimer's disease.

6-Gingerol Improves In Vitro Porcine Embryo Development by Reducing Oxidative Stress

6-Gingerol, the main active ingredient in ginger, exhibits a variety of biological activities, such as antioxidant, anti-inflammatory, and anticancer activities, and can affect cell development. However, the effects of 6-gingerol on mammalian reproductive processes, especially early embryonic development, are unclear. This study explored whether 6-gingerol can be used to improve the quality of in vitro-cultured porcine embryos. The results showed that 5 μM 6-gingerol significantly increased the blastocyst formation rates of porcine early embryos. 6-Gingerol attenuated intracellular reactive oxygen species accumulation and autophagy, increased intracellular glutathione levels, and increased mitochondrial activity. In addition, 6-gingerol upregulated NANOG, SRY-box transcription factor 2, cytochrome c oxidase subunit II, mechanistic target of rapamycin kinase, and RPTOR independent companion of MTOR complex 2 while downregulating Caspase 3, baculoviral IAP repeat containing 5, autophagy related 12, and Beclin 1. Most importantly, 6-gingerol significantly increased the levels of p-extracellular regulated protein kinase 1/2 while reducing the levels of p-c-Jun N-terminal kinase 1/2/3 and p-p38. These results indicate that 6-gingerol can promote the development of porcine early embryos in vitro.

Fish Models for Exploring Mitochondrial Dysfunction Affecting Neurodegenerative Disorders

Neurodegenerative disorders are characterized by the progressive loss of neuronal structure or function, resulting in memory loss and movement disorders. Although the detailed pathogenic mechanism has not been elucidated, it is thought to be related to the loss of mitochondrial function in the process of aging. Animal models that mimic the pathology of a disease are essential for understanding human diseases. In recent years, small fish have become ideal vertebrate models for human disease due to their high genetic and histological homology to humans, ease of in vivo imaging, and ease of genetic manipulation. In this review, we first outline the impact of mitochondrial dysfunction on the progression of neurodegenerative diseases. Then, we highlight the advantages of small fish as model organisms, and present examples of previous studies regarding mitochondria-related neuronal disorders. Lastly, we discuss the applicability of the turquoise killifish, a unique model for aging research, as a model for neurodegenerative diseases. Small fish models are expected to advance our understanding of the mitochondrial function in vivo, the pathogenesis of neurodegenerative diseases, and be important tools for developing therapies to treat diseases.

Modulation of Cellular Senescence in HEK293 and HepG2 Cells by Ultrafiltrates UPla and ULu Is Partly Mediated by Modulation of Mitochondrial Homeostasis under Oxidative Stress

Protein probes, including ultrafiltrates from the placenta (UPla) and lung (ULu) of postnatal rabbits, were investigated in premature senescent HEK293 and HepG2 cells to explore whether they could modulate cellular senescence. Tris-Tricine-PAGE, gene ontology (GO), and LC-MS/MS analysis were applied to describe the characteristics of the ultrafiltrates. HEK293 and HepG2 cells (both under 25 passages) exposed to a sub-toxic concentration of hydrogen peroxide (H2O2, 300 μM) became senescent; UPla (10 μg/mL), ULu (10 μg/mL), as well as positive controls lipoic acid (10 μg/mL) and transferrin (10 μg/mL) were added along with H2O2 to the cells. Cell morphology; cellular proliferation; senescence-associated beta-galactosidase (SA-β-X-gal) activity; expression of senescence biomarkers including p16 INK4A (p16), p21 Waf1/Cip1 (p21), HMGB1, MMP-3, TNF-α, IL-6, lamin B1, and phospho-histone H2A.X (γ-H2AX); senescence-related gene expression; reactive oxygen species (ROS) levels; and mitochondrial fission were examined. Tris-Tricine-PAGE revealed prominent detectable bands between 10 and 100 kDa. LC-MS/MS identified 150-180 proteins and peptides in the protein probes, and GO analysis demonstrated a distinct enrichment of proteins associated with "extracellular space" and "proteasome core complex". UPla and ULu modulated senescent cell morphology, improved cell proliferation, and decreased beta-galactosidase activity, intracellular and mitochondrial ROS production, and mitochondrial fission caused by H2O2. The results from this study demonstrated that UPla and Ulu, as well as lipoic acid and transferrin, could protect HEK293 and HepG2 cells from H2O2-induced oxidative damage via protecting mitochondrial homeostasis and thus have the potential to be explored in anti-aging therapies.

The Road Less Traveled: Uncovering the Convergence Toward Specific Pleiotropic Phenotypes in Aging

Aging is a complex process influenced by a wide range of environmental and molecular factors. Despite this complexity, individuals tend to age in highly similar ways, leading to the question of what drives this convergence. Recent research, including my own discoveries, suggests that the length of transcript molecules plays a crucial role in age-dependent changes to the transcriptome. Drawing inspiration from the road trip analogy of cellular transcription, I propose that a non-linear scaling law drives convergence towards specific pleiotropic phenotypes in biological aging. This scaling law is based on the notion that molecular changes observed during aging may reflect unspecific damage to cellular physiology. By validating this hypothesis, I can improve our understanding of biological aging and identify new candidate compounds for anti-aging interventions, as well as re-identify one known intervention. This work has actionable implications for improving human health and extending lifespans.

How the Disruption of Mitochondrial Redox Signalling Contributes to Ageing

In the past, mitochondrial reactive oxygen species (mtROS) were considered a byproduct of cellular metabolism. Due to the capacity of mtROS to cause oxidative damage, they were proposed as the main drivers of ageing and age-related diseases. Today, we know that mtROS are cellular messengers instrumental in maintaining cellular homeostasis. As cellular messengers, they are produced in specific places at specific times, and the intensity and duration of the ROS signal determine the downstream effects of mitochondrial redox signalling. We do not know yet all the processes for which mtROS are important, but we have learnt that they are essential in decisions that affect cellular differentiation, proliferation and survival. On top of causing damage due to their capacity to oxidize cellular components, mtROS contribute to the onset of degenerative diseases when redox signalling becomes dysregulated. Here, we review the best-characterized signalling pathways in which mtROS participate and those pathological processes in which they are involved. We focus on how mtROS signalling is altered during ageing and discuss whether the accumulation of damaged mitochondria without signalling capacity is a cause or a consequence of ageing.

Coenzyme Q10 supplementation improves the motor function of middle-aged mice by restoring the neuronal activity of the motor cortex

Physiological aging causes motor function decline and anatomical and biochemical changes in the motor cortex. We confirmed that middle-aged mice at 15-18 months old show motor function decline, which can be restored to the young adult level by supplementing with mitochondrial electron transporter coenzyme Q₁₀ (CoQ₁₀) as a water-soluble nanoformula by drinking water for 1 week. CoQ₁₀ supplementation concurrently improved brain mitochondrial respiration but not muscle strength. Notably, we identified an age-related decline in field excitatory postsynaptic potential (fEPSP) amplitude in the pathway from layers II/III to V of the primary motor area of middle-aged mice, which was restored to the young adult level by supplementing with CoQ₁₀ for 1 week but not by administering CoQ₁₀ acutely to brain slices. Interestingly, CoQ₁₀ with high-frequency stimulation induced NMDA receptor-dependent long-term potentiation (LTP) in layer V of the primary motor cortex of middle-aged mice. Importantly, the fEPSP amplitude showed a larger input‒output relationship after CoQ₁₀-dependent LTP expression. These data suggest that CoQ₁₀ restores the motor function of middle-aged mice by improving brain mitochondrial function and the basal fEPSP level of the motor cortex, potentially by enhancing synaptic plasticity efficacy. Thus, CoQ₁₀ supplementation may ameliorate the age-related decline in motor function in humans.

Using mass spectrometry imaging to visualize age-related subcellular disruption

Metabolic homeostasis balances the production and consumption of energetic molecules to maintain active, healthy cells. Cellular stress, which disrupts metabolism and leads to the loss of cellular homeostasis, is important in age-related diseases. We focus here on the role of organelle dysfunction in age-related diseases, including the roles of energy deficiencies, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, changes in metabolic flux in aging (e.g., Ca2+ and nicotinamide adenine dinucleotide), and alterations in the endoplasmic reticulum-mitochondria contact sites that regulate the trafficking of metabolites. Tools for single-cell resolution of metabolite pools and metabolic flux in animal models of aging and age-related diseases are urgently needed. High-resolution mass spectrometry imaging (MSI) provides a revolutionary approach for capturing the metabolic states of individual cells and cellular interactions without the dissociation of tissues. mass spectrometry imaging can be a powerful tool to elucidate the role of stress-induced cellular dysfunction in aging.

Discovery and properties of a monoclonal antibody targeting 8-oxoA, an oxidized adenine lesion in DNA and RNA

8-oxoA, a major oxidation product of adenosine, is a mispairing, mutagenic lesion that arises in DNA and RNA when ^•OH radicals or one-electron oxidants attack the C8 adenine atom or polymerases misincorporate 8-oxo(d)ATP. The danger of 8-oxoA is underscored by the existence of dedicated cellular repair machinery that explicitly excise it from DNA, the attenuation of translation induced by 8-oxoA-mRNA or damaged ribosomes, and its potency as a TLR7 agonist. Here we present the discovery, purification, and biochemical characterization of a new mouse IgGk1 monoclonal antibody (6E4) that specifically targets 8-oxoA. Utilizing an AchE-based competitive ELISA assay, we demonstrate the selectivity of 6E4 for 8-oxoA over a plethora of canonical and chemically modified nucleosides including 8-oxoG, A, m6A, 2-oxoA, and 5-hoU. We further show the ability of 6E4 to exclusively recognize 8-oxoA in nucleoside triphosphates (8-oxoATP) and DNA/RNA oligonucleotides containing a single 8-oxoA. 6E4 also binds 8-oxoA in duplex DNA/RNA antigens where the lesion is either paired correctly or base mismatched. Our findings define the 8-oxoAde nucleobase as the critical epitope and indicate mAb 6E4 is ideally suited for a broad range of immunological applications in nucleic acid detection and quality control.

Single-strand mismatch and damage patterns revealed by single-molecule DNA sequencing

Mutations accumulate in the genome of every cell of the body throughout life, causing cancer and other genetic diseases1-4. Almost all of these mosaic mutations begin as nucleotide mismatches or damage in only one of the two strands of the DNA prior to becoming double-strand mutations if unrepaired or misrepaired5. However, current DNA sequencing technologies cannot resolve these initial single-strand events. Here, we developed a single-molecule, long-read sequencing method that achieves single-molecule fidelity for single-base substitutions when present in either one or both strands of the DNA. It also detects single-strand cytosine deamination events, a common type of DNA damage. We profiled 110 samples from diverse tissues, including from individuals with cancer-predisposition syndromes, and define the first single-strand mismatch and damage signatures. We find correspondences between these single-strand signatures and known double-strand mutational signatures, which resolves the identity of the initiating lesions. Tumors deficient in both mismatch repair and replicative polymerase proofreading show distinct single-strand mismatch patterns compared to samples deficient in only polymerase proofreading. In the mitochondrial genome, our findings support a mutagenic mechanism occurring primarily during replication. Since the double-strand DNA mutations interrogated by prior studies are only the endpoint of the mutation process, our approach to detect the initiating single-strand events at single-molecule resolution will enable new studies of how mutations arise in a variety of contexts, especially in cancer and aging.