Low abundance of the matrix arm of complex I in mitochondria predicts longevity in mice

APOE genotype and biological age impact inter-omic associations related to bioenergetics

Apolipoprotein E (APOE) modifies human aging; specifically, the ε2 and ε4 alleles are among the strongest genetic predictors of longevity and Alzheimer's disease (AD) risk, respectively. However, detailed mechanisms for their influence on aging remain unclear. In the present study, we analyzed multi-omic association patterns across APOE genotypes, sex, and biological age (BA) axes in 2,229 community dwelling individuals. Our analysis, supported by validation in an independent cohort, identified diacylglycerols as the top APOE-associated plasma metabolites. However, despite the known opposing aging effects of the allele variants, both ε2- and ε4-carriers showed higher diacylglycerols compared to ε3-homozygotes. 'Omics association patterns of ε2-carriers and increased biological age were also counter-intuitively similar, displaying significantly increased associations between insulin resistance markers and energy-generating pathway metabolites. These results demonstrate the context-dependence of the influence of APOE, with ε2 potentially strengthening insulin resistance-like pathways in the decades prior to imparting its longevity benefits. Additionally, they provide an atlas of APOE-related 'omic associations and support the involvement of bioenergetic pathways in mediating the impact of APOE on aging.

Nano-encapsulated senolytic cocktail attenuates germ cell senescence in female mice

Low-quality oocytes directly affect fertilization and embryonic development, contributing to infertility in women, while germ cell senescence leads to reduced germ cell numbers and decreased egg quality. Dasatinib and quercetin (D and Q), as senolytic drugs, have been extensively explored in different age-related diseases. However, their effects on in vitro cultured senescent oocytes and the molecular mechanisms underpinning ovarian aging remain elusive. Here, we report that a nano-encapsulated senolytic D + Q cocktail efficiently improves the quality of post-ovulatory aging oocyte in vitro and follicle quantity in ovaries in a cyclophosphamide (Cy)-induced premature ovarian failure (POF) mouse model. Cocktail supplementation to cultured oocytes potently reduces reactive oxygen species (ROS) levels, maintains spindle integrity, decreases fragmented oocyte frequencies, rescues mislocalized cortical granules (CGs) and mitochondrial membrane potential (MMP), and alleviates DNA damage and apoptosis. Importantly, the cocktail effectively ameliorates fertility deficits in the model. Transcriptome analysis shows cocktail administration to fertility-deficient mice not only up-regulates developmental gene expression but also reduces senescence-associated secretory phenotype (SASP) accumulation. Therefore, our nano-encapsulated D + Q cocktail is a promising reagent for assisted reproductive technology and improving reproductive outcomes in POF.

Dynamic changes in gene expression through aging in Drosophila melanogaster heads

Work in many systems has shown large-scale changes in gene expression during aging. However, many studies employ just 2 arbitrarily chosen timepoints to measure expression and can only observe an increase or a decrease in expression between "young" and "old" animals, failing to capture any dynamic, nonlinear changes that occur throughout the aging process. We used RNA sequencing to measure expression in male head tissue at 15 timepoints through the lifespan of an inbred Drosophila melanogaster strain. We detected >6,000 significant, age-related genes, nearly all of which have been seen in previous Drosophila aging expression studies and that include several known to harbor lifespan-altering mutations. We grouped our gene set into 28 clusters via their temporal expression change, observing a diversity of trajectories; some clusters show a linear change over time, while others show more complex, nonlinear patterns. Notably, reanalysis of our dataset comparing the earliest and latest timepoints-mimicking a 2-timepoint design-revealed fewer differentially expressed genes (around 4,500). Additionally, those genes exhibiting complex expression trajectories in our multitimepoint analysis were most impacted in this reanalysis; their identification, and the inferred change in gene expression with age, was often dependent on the timepoints chosen. Informed by our trajectory-based clusters, we executed a series of gene enrichment analyses, identifying enriched functions/pathways in all clusters, including the commonly seen increase in stress- and immune-related gene expression with age. Finally, we developed a pair of accessible Shiny apps to enable exploration of our differential expression and gene enrichment results.

Metabolic reprogramming in T cell senescence: a novel strategy for cancer immunotherapy

The complex interplay between cancer progression and immune senescence is critically influenced by metabolic reprogramming in T cells. As T cells age, especially within the tumor microenvironment, they undergo significant metabolic shifts that may hinder their proliferation and functionality. This manuscript reviews how metabolic alterations contribute to T cell senescence in cancer and discusses potential therapeutic strategies aimed at reversing these metabolic changes. We explore interventions such as mitochondrial enhancement, glycolytic inhibition, and lipid metabolism adjustments that could rejuvenate senescent T cells, potentially restoring their efficacy in tumor suppression. This review also focuses on the significance of metabolic interventions in T cells with aging and further explores the future direction of the metabolism-based cancer immunotherapy in senescent T cells.

ELN regulates cellular senescence: Emerging hypothesis for a non-canonical role

Elastic fibers are well-known extracellular matrix components that are essential for elastic properties and thus function of many tissues. Tropoelastin is encoded by the ELN gene which is the main component of the elastic fibers. Elastic fibers decrease with aging and this decrease is proposed to contribute to this process. Senescent cells, cells that stop to proliferate and that instruct their microenvironment, accumulate with aging and promote it. Until recently, whether ELN expression and function is linked to cellular senescence was unknown. Here we will comment and extend recent results supporting a function of the ELN gene in protecting cells from cellular senescence. We will also discuss hypotheses on mechanisms by which ELN could regulate cellular senescence, and especially a hypothesis that involves a non-canonical function of ELN regulating the mitochondrial respiratory chain activity, thereby controlling oxidative stress and cellular senescence. These findings provide critical insights into the molecular and cellular processes potentially underlying the phenotypes driven by ELN deletion in the context of aging.

Developmental mitochondrial complex I activity determines lifespan

Aberrant mitochondrial function has been associated with an increasingly large number of human disease states. Observations from in vivo models where mitochondrial function is altered suggest that maladaptations to mitochondrial dysfunction may underpin disease pathology. We hypothesized that the severity of this maladaptation could be shaped by the plasticity of the system when mitochondrial dysfunction manifests. To investigate this, we have used inducible fly models of mitochondrial complex I (CI) dysfunction to reduce mitochondrial function at two stages of the fly lifecycle, from early development and adult eclosion. Here, we show that in early life (developmental) mitochondrial dysfunction results in severe reductions in survival and stress resistance in adulthood, while flies where mitochondrial function is perturbed from adulthood, are long-lived and stress resistant despite having up to a 75% reduction in CI activity. After excluding developmental defects as a cause, we went on to molecularly characterize these two populations of mitochondrially compromised flies, short- and long-lived. We find that our short-lived flies have unique transcriptomic, proteomic and metabolomic responses, which overlap significantly in discrete models of CI dysfunction. Our data demonstrate that early mitochondrial dysfunction via CI depletion elicits a maladaptive response, which severely reduces survival, while CI depletion from adulthood is insufficient to reduce survival and stress resistance.

Sex-dependent adaptations in heart mitochondria from transgenic mice overexpressing cytochrome b5 reductase-3

Cytochrome b5 reductase 3 (CYB5R3) overexpression upregulates mitochondrial biogenesis, function, and abundance in skeletal muscle and kidneys, and mimics some of the salutary effects of calorie restriction, with the most striking effects being observed in females. We aimed to investigate the mitochondrial adaptations prompted by CYB5R3 overexpression in the heart, an organ surprisingly overlooked in studies focused on this long-lived transgenic model despite the critical role played by CYB5R3 in supporting cardiomyocytes mitochondrial respiration. Given that CYB5R3 effects have been found to be sex-dependent, we focused our research on both males and females. CYB5R3 was efficiently overexpressed in cardiac tissue from transgenic mice, without any difference between sexes. The abundance of electron transport chain complexes markers and cytochrome c was higher in males than in females. CYB5R3 overexpression downregulated the levels of complexes markers in males but not females, without decreasing oxygen consumption capacity. CYB5R3 increased the size and abundance of cardiomyocytes mitochondria, and reduced thickness and preserved the length of mitochondria-endoplasmic reticulum contact sites in heart from males but not females. Metabolic changes were also highlighted in transgenic mice, with an upregulation of fatty acid oxidation markers, particularly in males. Our results support that CYB5R3 overexpression upregulates markers consistent with enhanced mitochondrial function in the heart, producing most of these actions in males, with illustrates the complexity of the CYB5R3-overexpressing transgenic model.

Managing Doxorubicin Cardiotoxicity: Insights Into Molecular Mechanisms and Protective Strategies

Cancer ranks as the second leading cause of death in the United States and poses a significant health challenge globally. Numerous therapeutic options exist for treating cancer, with chemotherapy being one of the most prominent. Chemotherapy involves the use of antineoplastic drugs, either alone or in combination with other medications, to target and kill cancer cells. However, these drugs can also adversely affect healthy cells, leading to various side effects. Among the most commonly used chemotherapy agents are anthracyclines, which include doxorubicin, daunorubicin, and epirubicin. Doxorubicin is particularly notable for its effectiveness but is also associated with significant cardiotoxicity, a common concern for patients undergoing chemotherapy. Unfortunately, there is currently no definitive treatment to prevent or reverse this cardiotoxicity. The cardiac effects of doxorubicin can manifest in several ways, including changes in electrocardiograms, arrhythmias, myocarditis, pericarditis, myocardial infarction, cardiomyopathy, heart failure, and congestive heart failure. These complications may arise during treatment, shortly after it concludes, or even weeks later. Various mechanisms have been proposed to explain doxorubicin-induced cardiotoxicity. Key factors include the inhibition of topoisomerase IIβ, mitochondrial damage, reactive oxygen species (ROS) production due to iron metabolism, increased oxidative stress, heightened inflammatory responses, and elevated rates of apoptosis and necrosis within cardiac tissue. This review article will provide a comprehensive overview of the current state of knowledge regarding doxorubicin-induced cardiomyopathy. We will explore the underlying molecular mechanisms contributing to this condition and discuss emerging therapeutic strategies aimed at mitigating its impact on cancer survivors.

The mitochondrial integrated stress response: A novel approach to anti-aging and pro-longevity

The ISR is a cellular signaling pathway that responds to various physiological changes and types of stimulation. The mitochondrial integrated stress response (ISRmt) is a stress response specific to mitochondria which is initiated by eIF2α phosphorylation and is responsive to mitochondrial stressors. The ISRmt triggers diverse metabolic responses reliant on activating transcription factor 4 (ATF4). The preliminary phases of ISRmt can provoke an adaptive stress response that antagonizes age-related diseases and promotes longevity. In this review, we provide an overview of the molecular mechanisms of the ISRmt, with a particular focus on its potential as a therapeutic target for age-related disease and the promotion of longevity.

Dynamic Changes in Gene Expression Through Aging in Drosophila melanogaster Heads

Work in many systems has shown large-scale changes in gene expression during aging. However, many studies employ just two, arbitrarily-chosen timepoints at which to measure expression, and can only observe an increase or a decrease in expression between "young" and "old" animals, failing to capture any dynamic, non-linear changes that occur throughout the aging process. We used RNA sequencing to measure expression in male head tissue at 15 timepoints through the lifespan of an inbred Drosophila melanogaster strain. We detected >6,000 significant, age-related genes, nearly all of which have been seen in previous fly aging expression studies, and which include several known to harbor lifespan-altering mutations. We grouped our gene set into 28 clusters via their temporal expression change, observing a diversity of trajectories; some clusters show a linear change over time, while others show more complex, non-linear patterns. Notably, re-analysis of our dataset comparing the earliest and latest timepoints - mimicking a two-timepoint design - revealed fewer differentially-expressed genes (around 4,500). Additionally, those genes exhibiting complex expression trajectories in our multi-timepoint analysis were most impacted in this re-analysis; Their identification, and the inferred change in gene expression with age, was often dependent on the timepoints chosen. Informed by our trajectory-based clusters, we executed a series of gene enrichment analyses, identifying enriched functions/pathways in all clusters, including the commonly seen increase in stress- and immune-related gene expression with age. Finally, we developed a pair of accessible shiny apps to enable exploration of our differential expression and gene enrichment results.

The role of CYP-sEH derived lipid mediators in regulating mitochondrial biology and cellular senescence: implications for the aging heart

Cellular senescence is a condition characterized by stable, irreversible cell cycle arrest linked to the aging process. The accumulation of senescent cells in the cardiac muscle can contribute to various cardiovascular diseases (CVD). Telomere shortening, epigenetic modifications, DNA damage, mitochondrial dysfunction, and oxidative stress are known contributors to the onset of cellular senescence in the heart. The link between mitochondrial processes and cellular senescence contributed to the age-related decline in cardiac function. These include changes in mitochondrial functions and behaviours that arise from various factors, including impaired dynamics, dysregulated biogenesis, mitophagy, mitochondrial DNA (mtDNA), reduced respiratory capacity, and mitochondrial structural changes. Thus, regulation of mitochondrial biology has a role in cellular senescence and cardiac function in aging hearts. Targeting senescent cells may provide a novel therapeutic approach for treating and preventing CVD associated with aging. CYP epoxygenases metabolize N-3 and N-6 polyunsaturated fatty acids (PUFA) into epoxylipids that are readily hydrolyzed to diol products by soluble epoxide hydrolase (sEH). Increasing epoxylipids levels or inhibition of sEH has demonstrated protective effects in the aging heart. Evidence suggests they may play a role in cellular senescence by regulating mitochondria, thus reducing adverse effects of aging in the heart. In this review, we discuss how mitochondria induce cellular senescence and how epoxylipids affect the senescence process in the aged heart.

Laminin-α2 chain deficiency in skeletal muscle causes dysregulation of multiple cellular mechanisms

LAMA2, coding for the laminin-α2 chain, is a crucial ECM component, particularly abundant in skeletal muscle. Mutations in LAMA2 trigger the often-lethal LAMA2-congenital muscular dystrophy (LAMA2-CMD). Various phenotypes have been linked to LAMA2-CMD; nevertheless, the precise mechanisms that malfunction during disease onset in utero remain unknown. We generated Lama2-deficient C2C12 cells and found that Lama2-deficient myoblasts display proliferation, differentiation, and fusion defects, DNA damage, oxidative stress, and mitochondrial dysfunction. Moreover, fetal myoblasts isolated from the dy W mouse model of LAMA2-CMD display impaired differentiation and fusion in vitro. We also showed that disease onset during fetal development is characterized by a significant down-regulation of gene expression in muscle fibers, causing pronounced effects on cytoskeletal organization, muscle differentiation, and altered DNA repair and oxidative stress responses. Together, our findings provide unique insights into the critical importance of the laminin-α2 chain for muscle differentiation and muscle cell homeostasis.

Accumulation of damaged mitochondria in aging astrocytes due to mitophagy dysfunction: Implications for susceptibility to mitochondrial stress

Aging disrupts brain function, leading to cognitive decline and neurodegenerative diseases. Senescent astrocytes, a hallmark of aging, contribute to this process through unknown mechanisms. This study investigates how senescence impacts astrocytic mitochondrial dynamics, which are critical for brain health. Our research, conducted using aged mouse brains, represents the first evidence of morphologically damaged mitochondria in astrocytes, along with functional alterations in mitochondrial respiration. In vitro experiments revealed that senescent astrocytes exhibit an increase in mitochondrial fragmentation and impaired mitophagy. Concurrently, there was an upregulation of mitochondrial biogenesis, indicating a compensatory response to mitochondrial damage. Importantly, these senescent astrocytes were more susceptible to mitochondrial stress, a vulnerability reversed by rapamycin treatment. These findings suggest a potential link between senescence, impaired mitochondrial quality control, and increased susceptibility to mitochondrial stress in astrocytes. Overall, our study highlights the importance of addressing mitochondrial dysfunction and senescence-related changes in astrocytes as a promising approach for developing therapies to counter age-related neurodegeneration and improve brain health.

Integrated approach to reducing polypharmacy in older people: exploring the role of oxidative stress and antioxidant potential therapy

Increased life expectancy, attributed to improved access to healthcare and drug development, has led to an increase in multimorbidity, a key contributor to polypharmacy. Polypharmacy is characterised by its association with a variety of adverse events in the older persons. The mechanisms involved in the development of age-related chronic diseases are largely unknown; however, altered redox homeostasis due to ageing is one of the main theories. In this context, the present review explores the development and interaction between different age-related diseases, mainly linked by oxidative stress. In addition, drug interactions in the treatment of various diseases are described, emphasising that the holistic management of older people and their pathologies should prevail over the individual treatment of each condition.

Cellular senescence in Alzheimer's disease: from physiology to pathology

Alzheimer's disease (AD) is one of the most common neurodegenerative disorders, characterized by the accumulation of Aβ and abnormal tau hyperphosphorylation. Despite substantial efforts in development of drugs targeting Aβ and tau pathologies, effective therapeutic strategies for AD remain elusive. Recent attention has been paid to the significant role of cellular senescence in AD progression. Mounting evidence suggests that interventions targeting cellular senescence hold promise in improving cognitive function and ameliorating hallmark pathologies in AD. This narrative review provides a comprehensive summary and discussion of the physiological roles, characteristics, biomarkers, and commonly employed in vivo and in vitro models of cellular senescence, with a particular focus on various cell types in the brain, including astrocytes, microglia, oligodendrocyte precursor cells, neurons, and endothelial cells. The review further delves into factors influencing cellular senescence in AD and emphasizes the significance of targeting cellular senescence as a promising approach for AD treatment, which includes the utilization of senolytics and senomorphics.

APOE Genotype and Biological Age Impact Inter-Omic Associations Related to Bioenergetics

Apolipoprotein E ( APOE ) modifies human aging; specifically, the ε2 and ε4 alleles are among the strongest genetic predictors of longevity and Alzheimer's disease (AD) risk, respectively. However, detailed mechanisms for their influence on aging remain unclear. Herein, we analyzed inter-omic, context-dependent association patterns across APOE genotypes, sex, and health axes in 2,229 community-dwelling individuals to test APOE genotypes for variation in metabolites and metabolite-associations tied to a previously-validated metric of biological aging (BA) based on blood biomarkers. Our analysis, supported by validation in an independent cohort, identified top APOE -associated plasma metabolites as diacylglycerols, which were increased in ε2-carriers and trended higher in ε4-carriers compared to ε3-homozygotes, despite the known opposing aging effects of the allele variants. 'Omics association patterns of ε2-carriers and increased biological age were also counter-intuitively similar, displaying increased associations between insulin resistance markers and energy-generating pathway metabolites. These results provide an atlas of APOE -related 'omic associations and support the involvement of bioenergetic pathways in mediating the impact of APOE on aging.

Selection for Late Reproduction Leads to Loss of Complex I Mitochondrial Capacity and Associated Increased Longevity in Seed Beetles

Mitochondria play a key role in aging. Here, we measured integrated mitochondrial functions in experimentally evolved lines of the seed beetle Acanthoscelides obtectus that were selected for early (E) or late (L) reproduction for nearly 4 decades. The 2 lines have markedly different lifespans (8 days and 13 days in the E and L lines, respectively). The contribution of the NADH pathway to maximal flux was lower in the L compared to the E beetles at young stages, associated with increased control by complex I. In contrast, the contribution of the Succinate pathway was higher in the L than in the E line, whereas the Proline pathway showed no differences between the lines. Our data suggest that selection of age at reproduction leads to a modulation of complex I activity in mitochondria and that mitochondria are a functional link between evolutionary and mechanistic theories of aging.

DAP3 promotes mitochondrial activity and tumour progression in hepatocellular carcinoma by regulating MT-ND5 expression

Cancer cells often exhibit fragmented mitochondria and dysregulated mitochondrial dynamics, but the underlying mechanism remains elusive. Here, we found that the mitochondrial protein death-associated protein 3 (DAP3) is localized to mitochondria and promotes the progression of hepatocellular carcinoma (HCC) by regulating mitochondrial function. DAP3 can promote the proliferation, migration, and invasion of HCC cells in vitro and in vivo by increasing mitochondrial respiration, inducing the epithelial-mesenchymal transition (EMT), and slowing cellular senescence. Mechanistically, DAP3 can increase mitochondrial complex I activity in HCC cells by regulating the translation and expression of MT-ND5. The phosphorylation of DAP3 at Ser185 mediated by AKT is the key event mediating the mitochondrial localization and function of DAP3 in HCC cells. In addition, the DAP3 expression in HCC samples is inversely correlated with patient survival. Our results revealed a mechanism by which DAP3 promotes mitochondrial function and HCC progression by regulating MT-ND5 translation and expression, indicating that DAP3 may be a therapeutic target for HCC.

The Roles of White Adipose Tissue and Liver NADPH in Dietary Restriction-Induced Longevity

Dietary restriction (DR) protocols frequently employ intermittent fasting. Following a period of fasting, meal consumption increases lipogenic gene expression, including that of NADPH-generating enzymes that fuel lipogenesis in white adipose tissue (WAT) through the induction of transcriptional regulators SREBP-1c and CHREBP. SREBP-1c knockout mice, unlike controls, did not show an extended lifespan on the DR diet. WAT cytoplasmic NADPH is generated by both malic enzyme 1 (ME1) and the pentose phosphate pathway (PPP), while liver cytoplasmic NADPH is primarily synthesized by folate cycle enzymes provided one-carbon units through serine catabolism. During the daily fasting period of the DR diet, fatty acids are released from WAT and are transported to peripheral tissues, where they are used for beta-oxidation and for phospholipid and lipid droplet synthesis, where monounsaturated fatty acids (MUFAs) may activate Nrf1 and inhibit ferroptosis to promote longevity. Decreased WAT NADPH from PPP gene knockout stimulated the browning of WAT and protected from a high-fat diet, while high levels of NADPH-generating enzymes in WAT and macrophages are linked to obesity. But oscillations in WAT [NADPH]/[NADP+] from feeding and fasting cycles may play an important role in maintaining metabolic plasticity to drive longevity. Studies measuring the WAT malate/pyruvate as a proxy for the cytoplasmic [NADPH]/[NADP+], as well as studies using fluorescent biosensors expressed in the WAT of animal models to monitor the changes in cytoplasmic [NADPH]/[NADP+], are needed during ad libitum and DR diets to determine the changes that are associated with longevity.

Towards Healthy Longevity: Comprehensive Insights from Molecular Targets and Biomarkers to Biological Clocks

Aging is a complex and time-dependent decline in physiological function that affects most organisms, leading to increased risk of age-related diseases. Investigating the molecular underpinnings of aging is crucial to identify geroprotectors, precisely quantify biological age, and propose healthy longevity approaches. This review explores pathways that are currently being investigated as intervention targets and aging biomarkers spanning molecular, cellular, and systemic dimensions. Interventions that target these hallmarks may ameliorate the aging process, with some progressing to clinical trials. Biomarkers of these hallmarks are used to estimate biological aging and risk of aging-associated disease. Utilizing aging biomarkers, biological aging clocks can be constructed that predict a state of abnormal aging, age-related diseases, and increased mortality. Biological age estimation can therefore provide the basis for a fine-grained risk stratification by predicting all-cause mortality well ahead of the onset of specific diseases, thus offering a window for intervention. Yet, despite technological advancements, challenges persist due to individual variability and the dynamic nature of these biomarkers. Addressing this requires longitudinal studies for robust biomarker identification. Overall, utilizing the hallmarks of aging to discover new drug targets and develop new biomarkers opens new frontiers in medicine. Prospects involve multi-omics integration, machine learning, and personalized approaches for targeted interventions, promising a healthier aging population.

Nucleobase adducts bind MR1 and stimulate MR1-restricted T cells

MR1T cells are a recently found class of T cells that recognize antigens presented by the major histocompatibility complex-I-related molecule MR1 in the absence of microbial infection. The nature of the self-antigens that stimulate MR1T cells remains unclear, hampering our understanding of their physiological role and therapeutic potential. By combining genetic, pharmacological, and biochemical approaches, we found that carbonyl stress and changes in nucleobase metabolism in target cells promote MR1T cell activation. Stimulatory compounds formed by carbonyl adducts of nucleobases were detected within MR1 molecules produced by tumor cells, and their abundance and antigenicity were enhanced by drugs that induce carbonyl accumulation. Our data reveal carbonyl-nucleobase adducts as MR1T cell antigens. Recognizing cells under carbonyl stress allows MR1T cells to monitor cellular metabolic changes with physiological and therapeutic implications.

Nutritional approaches targeting mitochondria for the prevention of sarcopenia

A decline in function and loss of mass, a condition known as sarcopenia, is observed in the skeletal muscles with aging. Sarcopenia has a negative effect on the quality of life of elderly. Individuals with sarcopenia are at particular risk for adverse outcomes, such as reduced mobility, fall-related injuries, and type 2 diabetes mellitus. Although the pathogenesis of sarcopenia is multifaceted, mitochondrial dysfunction is regarded as a major contributor for muscle aging. Hence, the development of preventive and therapeutic strategies to improve mitochondrial function during aging is imperative for sarcopenia treatment. However, effective and specific drugs that can be used for the treatment are not yet approved. Instead studies on the relationship between food intake and muscle aging have suggested that nutritional intake or dietary control could be an alternative approach for the amelioration of muscle aging. This narrative review approaches various nutritional components and diets as a treatment for sarcopenia by modulating mitochondrial homeostasis and improving mitochondria. Age-related changes in mitochondrial function and the molecular mechanisms that help improve mitochondrial homeostasis are discussed, and the nutritional components and diet that modulate these molecular mechanisms are addressed.

The role of telomerase reverse transcriptase in the mitochondrial protective functions of Angiotensin-(1-7) in diabetic CD34+ cells

Angiotensin (Ang)-(1-7) stimulates vasoprotective functions of diabetic (DB) CD34+ hematopoietic stem/progenitor cells partly by decreasing reactive oxygen species (ROS), increasing nitric oxide (NO) levels and decreasing TGFβ1 secretion. Telomerase reverse transcriptase (TERT) translocates to mitochondria and regulates ROS generation. Alternative splicing of TERT results in variants α-, β- and α-β-TERT, which may oppose functions of full-length (FL) TERT. This study tested if the protective functions of Ang-(1-7) or TGFβ1-silencing are mediated by mitoTERT and that diabetes decreases FL-TERT expression by inducing splicing. CD34+ cells were isolated from the peripheral blood mononuclear cells of nondiabetic (ND, n = 68) or DB (n = 74) subjects. NO and mitoROS levels were evaluated by flow cytometry. TERT splice variants and mitoDNA-lesions were characterized by qPCR. TRAP assay was used for telomerase activity. Decoy peptide was used to block mitochondrial translocation (mitoXTERT). TERT inhibitor or mitoXTERT prevented the effects of Ang-(1-7) on NO or mitoROS levels in DB-CD34+ cells. FL-TERT expression and telomerase activity were lower and mitoDNA-lesions were higher in DB cells compared to ND and were reversed by Ang-(1-7) or TGFβ1-silencing. The prevalence of TERT splice variants, with predominant β-TERT expression, was higher and the expression of FL-TERT was lower in DB cells (n = 25) compared to ND (n = 30). Ang-(1-7) or TGFβ1-silencing decreased TERT-splicing and increased FL-TERT. Blocking of β-splicing increased FL-TERT and protected mitoDNA in DB-cells. The findings suggest that diabetes induces TERT-splicing in CD34+ cells and that β-TERT splice variant largely contributes to the mitoDNA oxidative damage.

Mild Uncoupling of Mitochondria Synergistically Enhances Senolytic Specificity and Sensitivity of BH3 Mimetics

Despite immense potential as anti-aging interventions, applications of current senolytics are limited due to low sensitivity and specificity. We demonstrate the specific loss of complex I-linked coupled respiration and the inability to maintain mitochondrial membrane potential upon respiratory stimulation as a specific vulnerability of senescent cells. Further decreasing the mitochondrial membrane potential of senescent cells with a mitochondrial uncoupler synergistically enhances the in vitro senolytic efficacy of BH3 mimetic drugs, including Navitoclax, by up to two orders of magnitude, whereas non-senescent cells remain unaffected. Moreover, a short-term intervention combining the mitochondrial uncoupler BAM15 with Navitoclax at a dose two orders of magnitude lower than typically used rescues radiation-induced premature aging in an in vivo mouse model, as demonstrated by reduced frailty and improved cognitive function for at least eight months. Our study shows compromised mitochondrial functional capacity is a senescence-specific vulnerability that can be targeted by mild uncoupling in vitro and in vivo.

A Drosophila model of mitochondrial disease phenotypic heterogeneity

Mutations in genes that affect mitochondrial function cause primary mitochondrial diseases. Mitochondrial diseases are highly heterogeneous and even patients with the same mitochondrial disease can exhibit broad phenotypic heterogeneity, which is poorly understood. Mutations in subunits of mitochondrial respiratory complex I cause complex I deficiency, which can result in severe neurological symptoms and death in infancy. However, some complex I deficiency patients present with much milder symptoms. The most common nuclear gene mutated in complex I deficiency is the highly conserved core subunit NDUFS1. To model the phenotypic heterogeneity in complex I deficiency, we used RNAi lines targeting the Drosophila NDUFS1 homolog ND-75 with different efficiencies. Strong knockdown of ND-75 in Drosophila neurons resulted in severe behavioural phenotypes, reduced lifespan, altered mitochondrial morphology, reduced endoplasmic reticulum (ER)-mitochondria contacts and activation of the unfolded protein response (UPR). By contrast, weak ND-75 knockdown caused much milder behavioural phenotypes and changes in mitochondrial morphology. Moreover, weak ND-75 did not alter ER-mitochondria contacts or activate the UPR. Weak and strong ND-75 knockdown resulted in overlapping but distinct transcriptional responses in the brain, with weak knockdown specifically affecting proteosome activity and immune response genes. Metabolism was also differentially affected by weak and strong ND-75 knockdown including gamma-aminobutyric acid (GABA) levels, which may contribute to neuronal dysfunction in ND-75 knockdown flies. Several metabolic processes were only affected by strong ND-75 knockdown including the pentose phosphate pathway and the metabolite 2-hydroxyglutarate (2-HG), suggesting 2-HG as a candidate biomarker of severe neurological mitochondrial disease. Thus, our Drosophila model provides the means to dissect the mechanisms underlying phenotypic heterogeneity in mitochondrial disease.

Cellular senescence of renal tubular epithelial cells in acute kidney injury

Cellular senescence represents an irreversible state of cell-cycle arrest during which cells secrete senescence-associated secretory phenotypes, including inflammatory factors and chemokines. Additionally, these cells exhibit an apoptotic resistance phenotype. Cellular senescence serves a pivotal role not only in embryonic development, tissue regeneration, and tumor suppression but also in the pathogenesis of age-related degenerative diseases, malignancies, metabolic diseases, and kidney diseases. The senescence of renal tubular epithelial cells (RTEC) constitutes a critical cellular event in the progression of acute kidney injury (AKI). RTEC senescence inhibits renal regeneration and repair processes and, concurrently, promotes the transition of AKI to chronic kidney disease via the senescence-associated secretory phenotype. The mechanisms underlying cellular senescence are multifaceted and include telomere shortening or damage, DNA damage, mitochondrial autophagy deficiency, cellular metabolic disorders, endoplasmic reticulum stress, and epigenetic regulation. Strategies aimed at inhibiting RTEC senescence, targeting the clearance of senescent RTEC, or promoting the apoptosis of senescent RTEC hold promise for enhancing the renal prognosis of AKI. This review primarily focuses on the characteristics and mechanisms of RTEC senescence, and the impact of intervening RTEC senescence on the prognosis of AKI, aiming to provide a foundation for understanding the pathogenesis and providing potentially effective approaches for AKI treatment.

Cholesterol biosynthetic pathway induces cellular senescence through ERRα

Cellular senescence is a cell program induced by various stresses that leads to a stable proliferation arrest and to a senescence-associated secretory phenotype. Accumulation of senescent cells during age-related diseases participates in these pathologies and regulates healthy lifespan. Recent evidences point out a global dysregulated intracellular metabolism associated to senescence phenotype. Nonetheless, the functional contribution of metabolic homeostasis in regulating senescence is barely understood. In this work, we describe how the mevalonate pathway, an anabolic pathway leading to the endogenous biosynthesis of poly-isoprenoids, such as cholesterol, acts as a positive regulator of cellular senescence in normal human cells. Mechanistically, this mevalonate pathway-induced senescence is partly mediated by the downstream cholesterol biosynthetic pathway. This pathway promotes the transcriptional activity of ERRα that could lead to dysfunctional mitochondria, ROS production, DNA damage and a p53-dependent senescence. Supporting the relevance of these observations, increase of senescence in liver due to a high-fat diet regimen is abrogated in ERRα knockout mouse. Overall, this work unravels the role of cholesterol biosynthesis or level in the induction of an ERRα-dependent mitochondrial program leading to cellular senescence and related pathological alterations.

Upregulation of mitochondrial telomerase reverse transcriptase mediates the preventive effect of physical exercise on pathological cardiac hypertrophy via improving mitochondrial function and inhibiting oxidative stress

Physical exercise is a non-pharmacological intervention that helps prevent pathological cardiac hypertrophy. However, the underlying molecular mechanisms remain unclear. Telomerase reverse transcriptase (TERT) has non-telomeric functions such as protection against mitochondrial dysfunction and oxidative stress, and its myocardial expression is upregulated by physical exercise. Here, we found that physical exercise caused myocardial upregulation of mitochondrial TERT and sustenance during transverse aortic constriction (TAC)-induced cardiac hypertrophy. Overexpression of mitochondrial-targeted TERT (mito-TERT) via adeno-associated virus serotype 9 carrying the TERT-coding sequence fused with N-terminal mitochondrial-targeting sequence improved cardiac function and attenuated cardiac hypertrophy. Mechanistically, mito-TERT ameliorated mitochondrial dysfunction and oxidative stress, which were associated with improving the activity and subunit composition of complex I. Remarkably, the telomerase activator TA-65 also exhibited an antihypertrophic effect. Collectively, our results reveal a significant role for mito-TERT in mediating the antihypertrophic effect of physical exercise and demonstrate that TERT is a potential drug target for treating cardiac hypertrophy.

Phenotypic molecular features of long-lived animal species

One of the challenges facing science/biology today is uncovering the molecular bases that support and determine animal and human longevity. Nature, in offering a diversity of animal species that differ in longevity by more than 5 orders of magnitude, is the best 'experimental laboratory' to achieve this aim. Mammals, in particular, can differ by more than 200-fold in longevity. For this reason, most of the available evidence on this topic derives from comparative physiology studies. But why can human beings, for instance, reach 120 years whereas rats only last at best 4 years? How does nature change the longevity of species? Longevity is a species-specific feature resulting from an evolutionary process. Long-lived animal species, including humans, show adaptations at all levels of biological organization, from metabolites to genome, supported by signaling and regulatory networks. The structural and functional features that define a long-lived species may suggest that longevity is a programmed biological property.

Vutiglabridin exerts anti-ageing effects in aged mice through alleviating age-related metabolic dysfunctions

BACKGROUND

Ageing alters the ECM, leading to mitochondrial dysfunction and oxidative stress, which triggers an inflammatory response that exacerbates with age. Age-related changes impact satellite cells, affecting muscle regeneration, and the balance of proteins. Furthermore, ageing causes a decline in NAD+ levels, and alterations in fat metabolism that impact our health. These various metabolic issues become intricately intertwined with ageing, leading to a variety of individual-level diseases and profoundly affecting individuals' healthspan. Therefore, we hypothesize that vutiglabridin capable of alleviating these metabolic abnormalities will be able to ameliorate many of the problems associated with ageing.

METHOD

The efficacy of vutiglabridin, which alleviates metabolic issues by enhancing mitochondrial function, was assessed in aged mice treated with vutiglabridin and compared to untreated elderly mice. On young mice, vutiglabridin-treated aged mice, and non-treated aged mice, the Senescence-associated beta-galactosidase staining and q-PCR for ageing marker genes were carried out. Bulk RNA-seq was carried out on GA muscle, eWAT, and liver from each group of mice to compare differences in gene expression in various gene pathways. Blood from each group of mice was used to compare and analyze the ageing lipid profile.

RESULTS

SA-β-gal staining of eWAT, liver, kidney, and spleen of ageing mice showed that vutiglabridin had anti-ageing effects compared to the control group, and q-PCR of ageing marker genes including Cdkn1a and Cdkn2a in each tissue showed that vutiglabridin reduced the ageing process. In aged mice treated with vutiglabridin, GA muscle showed improved homeostasis compared to controls, eWAT showed restored insulin sensitivity and prevented FALC-induced inflammation, and liver showed reduced inflammation levels due to prevented TLO formation, improved mitochondrial complex I assembly, resulting in reduced ROS formation. Furthermore, blood lipid analysis revealed that ageing-related lipid profile was relieved in ageing mice treated with vutiglabridin versus the control group.

CONCLUSION

Vutiglabridin slows metabolic ageing mechanisms such as decreased insulin sensitivity, increased inflammation, and altered NAD+ metabolism in adipose tissue in mice experiments, while also retaining muscle homeostasis, which is deteriorated with age. It also improves the lipid profile in the blood and restores mitochondrial function in the liver to reduce ROS generation.

Sex-specific metabolic adaptations in transgenic mice overexpressing cytochrome b5 reductase-3

Cytochrome b5 reductase 3 (CYB5R3) activates respiratory metabolism in cellular systems and exerts a prolongevity action in transgenic mice overexpressing this enzyme, mimicking some of the beneficial effects of calorie restriction. The aim of our study was to investigate the role of sex on metabolic adaptations elicited by CYB5R3 overexpression, and how key markers related with mitochondrial function are modulated in skeletal muscle, one of the major contributors to resting energy expenditure. Young CYB5R3 transgenic mice did not exhibit the striking adaptations in carbon metabolism previously detected in older animals. CYB5R3 was efficiently overexpressed and targeted to mitochondria in skeletal muscle from transgenic mice regardless sex. Overexpression significantly elevated NADH in both sexes, although differences were not statistically significant for NAD+, and increased the abundance of cytochrome c and the fission protein DRP-1 in females but not in males. Moreover, while mitochondrial biogenesis and function markers (as TFAM, NRF-1 and cleaved SIRT3) were markedly upregulated by CYB5R3 overexpression in females, a downregulation was observed in males. Ultrastructural changes were also highlighted, with an increase in the number of mitochondria per surface unit, and in the size of intermyofibrillar mitochondria in transgenic females compared with their wild-type controls. Our results support that CYB5R3 overexpression upregulates markers consistent with enhanced mitochondrial biogenesis and function, and increases mitochondrial abundance in skeletal muscle, producing most of these potentially beneficial actions in females.

Mitochondria during T cell aging

Mitochondrial dysfunction is a hallmark of aging that contributes to inflammaging. It is characterized by alterations of the mitochondrial DNA, reduced respiratory capacity, decreased mitochondrial membrane potential and increased reactive oxygen species production. These primary alterations disrupt other interconnected and important mitochondrial-related processes such as metabolism, mitochondrial dynamics and biogenesis, mitophagy, calcium homeostasis or apoptosis. In this review, we gather the current knowledge about the different mitochondrial processes which are altered during aging, with special focus on their contribution to age-associated T cell dysfunction and inflammaging.

Reverse electron transfer is activated during aging and contributes to aging and age-related disease

Mechanisms underlying the depletion of NAD+ and accumulation of reactive oxygen species (ROS) in aging and age-related disorders remain poorly defined. We show that reverse electron transfer (RET) at mitochondrial complex I, which causes increased ROS production and NAD+ to NADH conversion and thus lowered NAD+ /NADH ratio, is active during aging. Genetic or pharmacological inhibition of RET decreases ROS production and increases NAD+ /NADH ratio, extending the lifespan of normal flies. The lifespan-extending effect of RET inhibition is dependent on NAD+ -dependent Sirtuin, highlighting the importance of NAD+ /NADH rebalance, and on longevity-associated Foxo and autophagy pathways. RET and RET-induced ROS and NAD+ /NADH ratio changes are prominent in human induced pluripotent stem cell (iPSC) model and fly models of Alzheimer's disease (AD). Genetic or pharmacological inhibition of RET prevents the accumulation of faulty translation products resulting from inadequate ribosome-mediated quality control, rescues relevant disease phenotypes, and extends the lifespan of Drosophila and mouse AD models. Deregulated RET is therefore a conserved feature of aging, and inhibition of RET may open new therapeutic opportunities in the context of aging and age-related diseases including AD.

Mitochondrial ROS production, oxidative stress and aging within and between species: Evidences and recent advances on this aging effector

Mitochondria play a wide diversity of roles in cell physiology and have a key functional implication in cell bioenergetics and biology of free radicals. As the main cellular source of oxygen radicals, mitochondria have been postulated as the mediators of the cellular decline associated with the biological aging. Recent evidences have shown that mitochondrial free radical production is a highly regulated mechanism contributing to the biological determination of longevity which is species-specific. This mitochondrial free radical generation rate induces a diversity of adaptive responses and derived molecular damage to cell components, highlighting mitochondrial DNA damage, with biological consequences that influence the rate of aging of a given animal species. In this review, we explore the idea that mitochondria play a fundamental role in the determination of animal longevity. Once the basic mechanisms are discerned, molecular approaches to counter aging may be designed and developed to prevent or reverse functional decline, and to modify longevity.

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.

Skeletal muscle mitochondrial interactome remodeling is linked to functional decline in aged female mice

Genomic, transcriptomic and proteomic approaches have been used to gain insight into molecular underpinnings of aging in laboratory animals and in humans. However, protein function in biological systems is under complex regulation and includes factors besides abundance levels, such as modifications, localization, conformation and protein-protein interactions. By making use of quantitative chemical cross-linking technologies, we show that changes in the muscle mitochondrial interactome contribute to mitochondrial functional decline in aging in female mice. Specifically, we identify age-related changes in protein cross-links relating to assembly of electron transport system complexes I and IV, activity of glutamate dehydrogenase, and coenzyme-A binding in fatty acid β-oxidation and tricarboxylic acid cycle enzymes. These changes show a remarkable correlation with complex I respiration differences within the same young-old animal pairs. Each observed cross-link can serve as a protein conformational or protein-protein interaction probe in future studies, which will provide further molecular insights into commonly observed age-related phenotypic differences. Therefore, this data set could become a valuable resource for additional in-depth molecular studies that are needed to better understand complex age-related molecular changes.

Chronic Cerebral Hypoperfusion-Induced Disturbed Proteostasis of Mitochondria and MAM Is Reflected in the CSF of Rats by Proteomic Analysis

Declining cerebral blood flow leads to chronic cerebral hypoperfusion which can induce neurodegenerative disorders, such as vascular dementia. The reduced energy supply of the brain impairs mitochondrial functions that could trigger further damaging cellular processes. We carried out stepwise bilateral common carotid occlusions on rats and investigated long-term mitochondrial, mitochondria-associated membrane (MAM), and cerebrospinal fluid (CSF) proteome changes. Samples were studied by gel-based and mass spectrometry-based proteomic analyses. We found 19, 35, and 12 significantly altered proteins in the mitochondria, MAM, and CSF, respectively. Most of the changed proteins were involved in protein turnover and import in all three sample types. We confirmed decreased levels of proteins involved in protein folding and amino acid catabolism, such as P4hb and Hibadh in the mitochondria by western blot. We detected reduced levels of several components of protein synthesis and degradation in the CSF as well as in the subcellular fractions, implying that hypoperfusion-induced altered protein turnover of brain tissue can be detected in the CSF by proteomic analysis.

A molecular signature defining exercise adaptation with ageing and in vivo partial reprogramming in skeletal muscle

Exercise promotes functional improvements in aged tissues, but the extent to which it simulates partial molecular reprogramming is unknown. Using transcriptome profiling from (1) a skeletal muscle-specific in vivo Oct3/4, Klf4, Sox2 and Myc (OKSM) reprogramming-factor expression murine model; (2) an in vivo inducible muscle-specific Myc induction murine model; (3) a translatable high-volume hypertrophic exercise training approach in aged mice; and (4) human exercise muscle biopsies, we collectively defined exercise-induced genes that are common to partial reprogramming. Late-life exercise training lowered murine DNA methylation age according to several contemporary muscle-specific clocks. A comparison of the murine soleus transcriptome after late-life exercise training to the soleus transcriptome after OKSM induction revealed an overlapping signature that included higher JunB and Sun1. Also, within this signature, downregulation of specific mitochondrial and muscle-enriched genes was conserved in skeletal muscle of long-term exercise-trained humans; among these was muscle-specific Abra/Stars. Myc is the OKSM factor most induced by exercise in muscle and was elevated following exercise training in aged mice. A pulse of MYC rewired the global soleus muscle methylome, and the transcriptome after a MYC pulse partially recapitulated OKSM induction. A common signature also emerged in the murine MYC-controlled and exercise adaptation transcriptomes, including lower muscle-specific Melusin and reactive oxygen species-associated Romo1. With Myc, OKSM and exercise training in mice, as well habitual exercise in humans, the complex I accessory subunit Ndufb11 was lower; low Ndufb11 is linked to longevity in rodents. Collectively, exercise shares similarities with genetic in vivo partial reprogramming. KEY POINTS: Advances in the last decade related to cellular epigenetic reprogramming (e.g. DNA methylome remodelling) toward a pluripotent state via the Yamanaka transcription factors Oct3/4, Klf4, Sox2 and Myc (OKSM) provide a window into potential mechanisms for combatting the deleterious effects of cellular ageing. Using global gene expression analysis, we compared the effects of in vivo OKSM-mediated partial reprogramming in skeletal muscle fibres of mice to the effects of late-life murine exercise training in muscle. Myc is the Yamanaka factor most induced by exercise in skeletal muscle, and so we compared the MYC-controlled transcriptome in muscle to Yamanaka factor-mediated and exercise adaptation mRNA landscapes in mice and humans. A single pulse of MYC is sufficient to remodel the muscle methylome. We identify partial reprogramming-associated genes that are innately altered by exercise training and conserved in humans, and propose that MYC contributes to some of these responses.

Mitochondrial Complex I, a Possible Sensible Site of cAMP Pathway in Aging

In mammals during aging, reactive oxygen species (ROS), produced by the mitochondrial respiratory chain, cause oxidative damage of macromolecules leading to respiratory chain dysfunction, which in turn increases ROS mitochondrial production. Many efforts have been made to understand the role of oxidative stress in aging and age-related diseases. The complex I of the mitochondrial respiratory chain is the major source of ROS production and its dysfunctions have been associated with several forms of neurodegeneration, other common human diseases and aging. Complex I-ROS production and complex I content have been proposed as the major determinants for longevity. The cAMP signal has a role in the regulation of complex I activity and the decrease of ROS production. In the last years, an increasing number of studies have attempted to activate cAMP signaling to treat age-related diseases associated with mitochondrial dysfunctions and ROS production. This idea comes from a long-line of studies showing a main role of cAMP signal in the memory consolidation mechanism and in the regulation of mitochondrial functions. Here, we discuss several evidences on the possible connection between complex I and cAMP pathway in the aging process.

Cellular Senescence and Ageing

Cellular senescence has become a subject of great interest within the ageing research field over the last 60 years, from the first observation in vitro by Leonard Hayflick and Paul Moorhead in 1961, to novel findings of phenotypic sub-types and senescence-like phenotype in post-mitotic cells. It has essential roles in wound healing, tumour suppression and the very first stages of human development, while causing widespread damage and dysfunction with age leading to a raft of age-related diseases. This chapter discusses these roles and their interlinking pathways, and how the observed accumulation of senescent cells with age has initiated a whole new field of ageing research, covering pathologies in the heart, liver, kidneys, muscles, brain and bone. This chapter will also examine how senescent cell accumulation presents in these different tissues, along with their roles in disease development. Finally, there is much focus on developing treatments for senescent cell accumulation in advanced age as a method of alleviating age-related disease. We will discuss here the various senolytic and senostatic treatment approaches and their successes and limitations, and the innovative new strategies being developed to address the differing effects of cellular senescence in ageing and disease.

Intragastric administration of Pien Tze Huang enhanced wound healing in diabetes by inhibiting inflammation and improving energy generation

BACKGROUND AND PURPOSE

As a complex and challenging complication for the patients with diabetes mellitus, diabetic ulcers are difficult to heal and current strategies cannot fulfill the patients' requirements. Pien Tze Huang (PZH) is a standardized medicine approved for various wounds treatments, and this study systematically investigated the effect and mechanism of intragastric administration of PZH (I-PZH) on diabetic wound healing.

METHODS AND RESULTS

The effect of I-PZH on the healing of full-thickness wounds in rats with diabetes mellitus which was induced by high fat diet followed by streptozotocin injection was evaluated, and RNA sequencing (RNA-seq) and targeted central carbon metabolism metabolomics were combined to explore the underlying mechanism. I-PZH promoted wound healing, facilitated extracellular matrix synthesis, and maintained body weight of rats, but did not affect fasting blood glucose levels. Additionally, I-PZH significantly decreased 8-OHdG, cleaved caspase 3 and MMP9 levels, and increased TGF-β1 expression. RNA-seq analysis showed that I-PZH inhibited inflammation and that the vital common targets were TLR2, IL-17A and IL-1β; specifically affected "energy derivation by oxidation of organic compounds" with UQCRC1, NDUFS3 and SDHA as vital specific targets. Further experiments confirmed that I-PZH reduced TLR2, IL-17A and IL-1β, increased UQCRC1, SDHA, NDUFS3, promoted ATP synthesis and restored activity of mitochondrial respiratory chain complexes I and III in diabetic wounds. Metabolomics by HPLC-MS/MS analysis showed that I-PZH reversed multiple energy metabolism-related metabolites such as glucuronic acid, GMP, d-gluconic acid, cis-aconitic acid, ribose 5-phosphate and pantothenate.

CONCLUSION

This study highlights the important role of inflammation and energy generation in diabetic wound healing, reveals wound repair mechanism of PZH and promotes its clinical application in diabetic wound treatment.

Methionine Metabolism Is Down-Regulated in Heart of Long-Lived Mammals

Methionine constitutes a central hub of intracellular metabolic adaptations leading to an extended longevity (maximum lifespan). The present study follows a comparative approach analyzing methionine and related metabolite and amino acid profiles using an LC-MS/MS platform in the hearts of seven mammalian species with a longevity ranging from 3.8 to 57 years. Our findings demonstrate the existence of species-specific heart phenotypes associated with high longevity characterized by: (i) low concentration of methionine and its related sulphur-containing metabolites; (ii) low amino acid pool; and (iii) low choline concentration. Our results support the existence of heart metabotypes characterized by a down-regulation in long-lived species, supporting the idea that in longevity, less is more.

Therapeutic Stimulation of Glycolytic ATP Production for Treating ROS-Mediated Cellular Senescence

Cellular senescence is conditioned through two interrelated processes, i.e., a reduction in adenosine triphosphate (ATP) and the enhancement of reactive oxygen species (ROS) production levels in mitochondria. ATP shortages primarily influence the energy-intensive synthesis of large biomolecules, such as deoxyribonucleic acid (DNA). In addition, as compared to small biomolecules, large biomolecules are more prone to ROS-mediated damaging effects. Based on the available evidence, we suggest that the stimulation of anaerobic glycolytic ROS-independent ATP production could restrain cellular senescence. Consistent with this notion, non-drug related intermittent hypoxia (IH)-based therapy could be effectively applied in sports medicine, as well as for supporting the physical activity of elderly patients and prophylactics of various age-related disorders. Moreover, drug therapy aiming to achieve the partial blockade of respiratory chain and downstream compensatory glycolysis enhancement could prove to be useful for treating cardiovascular, neurological and hormonal diseases. We maintain that non-drug/drug-related therapeutic interventions applied in combination over the entire lifespan could significantly rejuvenate and prolong a high quality of life for individuals.

Mitochondrial dysfunction in cell senescence and aging

Mitochondrial dysfunction and cell senescence are hallmarks of aging and are closely interconnected. Mitochondrial dysfunction, operationally defined as a decreased respiratory capacity per mitochondrion together with a decreased mitochondrial membrane potential, typically accompanied by increased production of oxygen free radicals, is a cause and a consequence of cellular senescence and figures prominently in multiple feedback loops that induce and maintain the senescent phenotype. Here, we summarize pathways that cause mitochondrial dysfunction in senescence and aging and discuss the major consequences of mitochondrial dysfunction and how these consequences contribute to senescence and aging. We also highlight the potential of senescence-associated mitochondrial dysfunction as an antiaging and antisenescence intervention target, proposing the combination of multiple interventions converging onto mitochondrial dysfunction as novel, potent senolytics.

Short senolytic or senostatic interventions rescue progression of radiation-induced frailty and premature ageing in mice

Cancer survivors suffer from progressive frailty, multimorbidity, and premature morbidity. We hypothesise that therapy-induced senescence and senescence progression via bystander effects are significant causes of this premature ageing phenotype. Accordingly, the study addresses the question whether a short anti-senescence intervention is able to block progression of radiation-induced frailty and disability in a pre-clinical setting. Male mice were sublethally irradiated at 5 months of age and treated (or not) with either a senolytic drug (Navitoclax or dasatinib + quercetin) for 10 days or with the senostatic metformin for 10 weeks. Follow-up was for 1 year. Treatments commencing within a month after irradiation effectively reduced frailty progression (p<0.05) and improved muscle (p<0.01) and liver (p<0.05) function as well as short-term memory (p<0.05) until advanced age with no need for repeated interventions. Senolytic interventions that started late, after radiation-induced premature frailty was manifest, still had beneficial effects on frailty (p<0.05) and short-term memory (p<0.05). Metformin was similarly effective as senolytics. At therapeutically achievable concentrations, metformin acted as a senostatic neither via inhibition of mitochondrial complex I, nor via improvement of mitophagy or mitochondrial function, but by reducing non-mitochondrial reactive oxygen species production via NADPH oxidase 4 inhibition in senescent cells. Our study suggests that the progression of adverse long-term health and quality-of-life effects of radiation exposure, as experienced by cancer survivors, might be rescued by short-term adjuvant anti-senescence interventions.

Reduced expression of mitochondrial complex I subunit Ndufs2 does not impact healthspan in mice

Aging in mammals leads to reduction in genes encoding the 45-subunit mitochondrial electron transport chain complex I. It has been hypothesized that normal aging and age-related diseases such as Parkinson’s disease are in part due to modest decrease in expression of mitochondrial complex I subunits. By contrast, diminishing expression of mitochondrial complex I genes in lower organisms increases lifespan. Furthermore, metformin, a putative complex I inhibitor, increases healthspan in mice and humans. In the present study, we investigated whether loss of one allele of Ndufs2, the catalytic subunit of mitochondrial complex I, impacts healthspan and lifespan in mice. Our results indicate that Ndufs2 hemizygous mice (Ndufs2^+/−) show no overt impairment in aging-related motor function, learning, tissue histology, organismal metabolism, or sensitivity to metformin in a C57BL6/J background. Despite a significant reduction of Ndufs2 mRNA, the mice do not demonstrate a significant decrease in complex I function. However, there are detectable transcriptomic changes in individual cell types and tissues due to loss of one allele of Ndufs2. Our data indicate that a 50% decline in mRNA of the core mitochondrial complex I subunit Ndufs2 is neither beneficial nor detrimental to healthspan.

Mitochondrial complex I as a therapeutic target for Alzheimer's disease

Alzheimer's disease (AD), the most prominent form of dementia in the elderly, has no cure. Strategies focused on the reduction of amyloid beta or hyperphosphorylated Tau protein have largely failed in clinical trials. Novel therapeutic targets and strategies are urgently needed. Emerging data suggest that in response to environmental stress, mitochondria initiate an integrated stress response (ISR) shown to be beneficial for healthy aging and neuroprotection. Here, we review data that implicate mitochondrial electron transport complexes involved in oxidative phosphorylation as a hub for small molecule-targeted therapeutics that could induce beneficial mitochondrial ISR. Specifically, partial inhibition of mitochondrial complex I has been exploited as a novel strategy for multiple human conditions, including AD, with several small molecules being tested in clinical trials. We discuss current understanding of the molecular mechanisms involved in this counterintuitive approach. Since this strategy has also been shown to enhance health and life span, the development of safe and efficacious complex I inhibitors could promote healthy aging, delaying the onset of age-related neurodegenerative diseases.

Membrane lipids and maximum lifespan in clownfish

The longevity-homeoviscous adaptation (LHA) theory of ageing states that lipid composition of cell membranes is linked to metabolic rate and lifespan, which has been widely shown in mammals and birds but not sufficiently in fish. In this study, two species of the genus Amphiprion (Amphiprion percula and Amphiprion clarkii, with estimated maximum lifespan potentials [MLSP] of 30 and 9-16 years, respectively) and the damselfish Chromis viridis (estimated MLSP of 1-2 years) were chosen to test the LHA theory of ageing in a potential model of exceptional longevity. Brain, livers and samples of skeletal muscle were collected for lipid analyses and integral part in the computation of membrane peroxidation indexes (PIn) from phospholipid (PL) fractions and PL fatty acid composition. When only the two Amphiprion species were compared, results pointed to the existence of a negative correlation between membrane PIn value and maximum lifespan, well in line with the predictions from the LHA theory of ageing. Nevertheless, contradictory data were obtained when the two Amphiprion species were compared to the shorter-lived C. viridis. These results along with those obtained in previous studies on fish denote that the magnitude (and sometimes the direction) of the differences observed in membrane lipid composition and peroxidation index with MLSP cannot explain alone the diversity in longevity found among fishes.

Regulation of reverse electron transfer at mitochondrial complex I by unconventional Notch action in cancer stem cells

Metabolic flexibility is a hallmark of many cancers where mitochondrial respiration is critically involved, but the molecular underpinning of mitochondrial control of cancer metabolic reprogramming is poorly understood. Here, we show that reverse electron transfer (RET) through respiratory chain complex I (RC-I) is particularly active in brain cancer stem cells (CSCs). Although RET generates ROS, NAD⁺/NADH ratio turns out to be key in mediating RET effect on CSC proliferation, in part through the NAD⁺-dependent Sirtuin. Mechanistically, Notch acts in an unconventional manner to regulate RET by interacting with specific RC-I proteins containing electron-transporting Fe-S clusters and NAD(H)-binding sites. Genetic and pharmacological interference of Notch-mediated RET inhibited CSC growth in Drosophila brain tumor and mouse glioblastoma multiforme (GBM) models. Our results identify Notch as a regulator of RET and RET-induced NAD⁺/NADH balance, a critical mechanism of metabolic reprogramming and a metabolic vulnerability of cancer that may be exploited for therapeutic purposes.