Identification and Application of Gene Expression Signatures Associated with Lifespan Extension

Cysteine depletion triggers adipose tissue thermogenesis and weight loss

Caloric restriction and methionine restriction-driven enhanced lifespan and healthspan induces 'browning' of white adipose tissue, a metabolic response that increases heat production to defend core body temperature. However, how specific dietary amino acids control adipose thermogenesis is unknown. Here, we identified that weight loss induced by caloric restriction in humans reduces thiol-containing sulfur amino acid cysteine in white adipose tissue. Systemic cysteine depletion in mice causes lethal weight loss with increased fat utilization and browning of adipocytes that is rescued upon restoration of cysteine in diet. Mechanistically, cysteine-restriction-induced adipose browning and weight loss requires sympathetic nervous system-derived noradrenaline signalling via β3-adrenergic-receptors that is independent of FGF21 and UCP1. In obese mice, cysteine deprivation induced rapid adipose browning, increased energy expenditure leading to 30% weight loss and reversed metabolic inflammation. These findings establish that cysteine is essential for organismal metabolism as removal of cysteine in the host triggers adipose browning and rapid weight loss.

Systematic transcriptomics analysis of calorie restriction and rapamycin unveils their synergistic interaction in prolonging cellular lifespan

Aging is a multifaceted biological process marked by the decline in both mitotic and postmitotic cellular function, often central to the development of age-related diseases. In the pursuit of slowing or even reversing the aging process, a prominent strategy of significant interest is calorie restriction (CR), also known as dietary restriction, and the potential influence of a drug called rapamycin (RM). Both CR and RM have demonstrated the capacity to extend healthspan and lifespan across a diverse array of species, including yeast, worms, flies, and mice. Nevertheless, their individual and combined effects on mitotic and postmitotic cells, as well as their comparative analysis, remain areas that demand a thorough investigation. In this study, we employ RNA-sequencing methodologies to comprehensively analyze the impact of CR, RM, and their combination (CR + RM) on gene expression in yeast cells. Our analysis uncovers distinctive, overlapping, and even contrasting patterns of gene regulation, illuminating the unique and shared effects of CR and RM. Furthermore, the transcriptional synergistic interaction of CR + RM is validated in extending the lifespan of both yeast and human cells.

Regeneration leads to global tissue rejuvenation in aging sexual planarians

The possibility of reversing the adverse impacts of aging could significantly reduce age-related diseases and improve quality of life in older populations. Here we report that the sexual lineage of the planarian Schmidtea mediterranea exhibits physiological decline within 18 months of birth, including altered tissue architecture, impaired fertility and motility, and increased oxidative stress. Single-cell profiling of young and older planarian heads uncovered loss of neurons and muscle, increase of glia, and revealed minimal changes in somatic pluripotent stem cells, along with molecular signatures of aging across tissues. Remarkably, amputation followed by regeneration of lost tissues in older planarians led to reversal of these age-associated changes in tissues both proximal and distal to the injury at physiological, cellular and molecular levels. Our work suggests mechanisms of rejuvenation in both new and old tissues concurring with planarian regeneration, which may provide valuable insights for antiaging interventions.

The Mitochondria-Targeted Peptide Therapeutic Elamipretide Improves Cardiac and Skeletal Muscle Function During Aging Without Detectable Changes in Tissue Epigenetic or Transcriptomic Age

Aging-related decreases in cardiac and skeletal muscle function are strongly associated with various comorbidities. Elamipretide (ELAM), a novel mitochondria-targeted peptide, has demonstrated broad therapeutic efficacy in ameliorating disease conditions associated with mitochondrial dysfunction across both clinical and pre-clinical models. Herein, we investigated the impact of 8-week ELAM treatment on pre- and post-measures of C57BL/6J mice frailty, skeletal muscle, and cardiac muscle function, coupled with post-treatment assessments of biological age and affected molecular pathways. We found that health status, as measured by frailty index, cardiac strain, diastolic function, and skeletal muscle force, is significantly diminished with age, with skeletal muscle force changing in a sex-dependent manner. Conversely, ELAM mitigated frailty accumulation and was able to partially reverse these declines, as evidenced by treatment-induced increases in cardiac strain and muscle fatigue resistance. Despite these improvements, we did not detect statistically significant changes in gene expression or DNA methylation profiles indicative of molecular reorganization or reduced biological age in most ELAM-treated groups. However, pathway analyses revealed that ELAM treatment showed pro-longevity shifts in gene expression, such as upregulation of genes involved in fatty acid metabolism, mitochondrial translation, and oxidative phosphorylation, and downregulation of inflammation. Together, these results indicate that ELAM treatment is effective at mitigating signs of sarcopenia and cardiac dysfunction in an aging mouse model, but that these functional improvements occur independently of detectable changes in epigenetic and transcriptomic age. Thus, some age-related changes in function may be uncoupled from changes in molecular biological age.

A torpor-like state in mice slows blood epigenetic aging and prolongs healthspan

Torpor and hibernation are extreme physiological adaptations of homeotherms associated with pro-longevity effects. Yet the underlying mechanisms of how torpor affects aging, and whether hypothermic and hypometabolic states can be induced to slow aging and increase healthspan, remain unknown. Here we demonstrate that the activity of a spatially defined neuronal population in the preoptic area, which has previously been identified as a torpor-regulating brain region, is sufficient to induce a torpor-like state (TLS) in mice. Prolonged induction of TLS slows epigenetic aging across multiple tissues and improves healthspan. We isolate the effects of decreased metabolic rate, long-term caloric restriction, and decreased core body temperature (Tb) on blood epigenetic aging and find that the decelerating effect of TLSs on aging is mediated by decreased Tb. Taken together, our findings provide novel mechanistic insight into the decelerating effects of torpor and hibernation on aging and support the growing body of evidence that Tb is an important mediator of the aging processes.

Targeting farnesoid X receptor as aging intervention therapy

Environmental toxicants have been linked to aging and age-related diseases. The emerging evidence has shown that the enhancement of detoxification gene expression is a common transcriptome marker of long-lived mice, Drosophila melanogaster, and Caenorhabditis elegans. Meanwhile, the resistance to toxicants was increased in long-lived animals. Here, we show that farnesoid X receptor (FXR) agonist obeticholic acid (OCA), a marketed drug for the treatment of cholestasis, may extend the lifespan and healthspan both in C. elegans and chemical-induced early senescent mice. Furthermore, OCA increased the resistance of worms to toxicants and activated the expression of detoxification genes in both mice and C. elegans. The longevity effects of OCA were attenuated in Fxr -/- mice and Fxr homologous nhr-8 and daf-12 mutant C. elegans. In addition, metabolome analysis revealed that OCA increased the endogenous agonist levels of the pregnane X receptor (PXR), a major nuclear receptor for detoxification regulation, in the liver of mice. Together, our findings suggest that OCA has the potential to lengthen lifespan and healthspan by activating nuclear receptor-mediated detoxification functions, thus, targeting FXR may offer to promote longevity.

Activation of Nuclear Receptor CAR: A Pathway to Delay Aging through Enhanced Capacity for Xenobiotic Resistance

Environmental factors are linked to aging and age-related diseases. Emerging evidence suggests that enhancing body's resistance to xenobiotics might be an anti-aging strategy. The constitutive androstane receptor (CAR) regulates drug-metabolizing enzymes and transporters, coordinating metabolism and immune responses to adapt to stress triggered by exogenous exposure. However, the impact of activating CAR on aging remains unknown. In this study, Caenorhabditis elegans (C. elegans), drug-induced premature aging mice, and senescence accelerated P8 (SAMP8) mice are used as models to explore the effects of CAR activation on lifespan and healthspan, along with the underlying mechanisms. The results showed that hCAR agonist CITCO and mCAR agonist TCPOBOP prolonged the lifespan and healthspan in model organism. The longevity effects of CITCO and TCPOBOP were attenuated in CAR homozygous nhr-8/daf-12 mutant C. elegans as well as CAR-/- mice. In C. elegans, CITCO activated both anti-stress and detoxification genes, and increased the resistance to environmental adversities. Additionally, the lifespan-extending and xenobiotic resistant effects of CITCO might be related to the regulation of age-related pathways. Furthermore, CITCO improved age-related neurodegeneration in C. elegans models. Taken together, the results suggest that the longevity effects of CAR agonists may be related to the enhancement of xenobiotic resistance of animals.

Ergothioneine improves healthspan of aged animals by enhancing cGPDH activity through CSE-dependent persulfidation

Ergothioneine (ET), a dietary thione/thiol, is receiving growing attention for its possible benefits in healthy aging and metabolic resilience. Our study investigates ET's effects on healthspan in aged animals, revealing lifespan extension and enhanced mobility in Caenorhabditis elegans, accompanied by improved stress resistance and reduced age-associated biomarkers. In aged rats, ET administration enhances exercise endurance, muscle mass, and vascularization, concomitant with higher NAD+ levels in muscle. Mechanistically, ET acts as an alternative substrate for cystathionine gamma-lyase (CSE), stimulating H2S production, which increases protein persulfidation of more than 300 protein targets. Among these, protein-persulfidation-driven activation of cytosolic glycerol-3-phosphate dehydrogenase (cGPDH) primarily contributes to the ET-induced NAD+ increase. ET's effects are abolished in models lacking CSE or cGPDH, highlighting the essential role of H2S signaling and protein persulfidation. These findings elucidate ET's multifaceted actions and provide insights into its therapeutic potential for combating age-related muscle decline and metabolic perturbations.

Lipid peroxidation products induce carbonyl stress, mitochondrial dysfunction, and cellular senescence in human and murine cells

Lipid enals are electrophilic products of lipid peroxidation that induce genotoxic and proteotoxic stress by covalent modification of DNA and proteins, respectively. As lipid enals accumulate to substantial amounts in visceral adipose during obesity and aging, we hypothesized that biogenic lipid enals may represent an endogenously generated, and therefore physiologically relevant, senescence inducers. To that end, we identified that 4-hydroxynonenal (4-HNE), 4-hydroxyhexenal (4-HHE) or 4-oxo-2-nonenal (4-ONE) initiate the cellular senescence program of IMR90 fibroblasts and murine adipose stem cells. In such cells, lipid enals induced accumulation of γH2AX foci, increased p53 signaling, enhanced expression of p21Cip1, and upregulated the expression and secretion of numerous cytokines, chemokines, and regulatory factors independently from NF-κB activation. Concomitantly, lipid enal treatment resulted in covalent modification of mitochondrial proteins, reduced mitochondrial spare respiratory capacity, altered nucleotide pools, and increased the phosphorylation of AMP kinase. Lipid-induced senescent cells upregulated BCL2L1 (Bcl-xL) and BCL2L2 (Bcl-w). and were resistant to apoptosis while pharmacologic inhibition of BAX/BAK macropores attenuated lipid-induced senescence. In situ, the 4-HNE scavenger L-carnosine ameliorated the development of the cellular senescence, while in visceral fat of obese C57BL/6J mice, L-carnosine reduced the abundance of 4-HNE-modified proteins and blunted the expression of senescence biomarkers CDKN1A (p21Cip1), PLAUR, BCL2L1, and BCL2L2. Taken together, the results suggest that lipid enals are endogenous regulators of cellular senescence and that biogenic lipid-induced senescence (BLIS) may represent a mechanistic link between oxidative stress and age-dependent pathologies.

Downregulation of the NF-κB protein p65 is a shared phenotype among most anti-aging interventions

Many aspects of inflammation increase with aging in mice and humans. Transcriptomic analysis revealed that many murine anti-aging interventions produce lower levels of pro-inflammatory proteins. Here, we explore the hypothesis that different longevity interventions diminish NF-κB levels, potentially mediating some of the anti-inflammatory benefits of lifespan-extending interventions. We found that the NF-κB protein p65 is significantly downregulated in the liver of several kinds of slow-aging mice. These included both sexes of GHRKO and Snell Dwarf mutant mice, and in females only of PAPPA KO mice. P65 is also lower in both sexes of mice treated with rapamycin, canagliflozin, meclizine, or acarbose, and in mice undergoing caloric restriction. Two drugs that extend lifespan of male mice, i.e. 17α-estradiol and astaxanthin, however, did not produce lower levels of p65. We also measured other canonical NF-κB signaling regulators, including the activators IKKα and IKKβ and the inhibitor IκB-α. We found that those regulators do not consistently change in a direction that would lead to of NF-κB inhibition. In contrast, we found that NCoR1, an HDAC3 cofactor and a transcription co-repressor that regulates p65 activity, was also downregulated in many of these mouse models. Finally, we report downregulation of three p65 target proteins that regulate the metabolic and inflammatory states of the liver (HNF4α, IL-1β, and CRP) in multiple slow-aging mouse models. Together, these data suggest that NF-κB signaling, might be inhibited in liver of multiple varieties of slow aging mice. This establishes p65 as a potential target for novel longevity interventions.

The Peroxidation of Lipids, Cellular Senescence and Aging

The inducers of cellular senescence as a determinant in organismal aging are complex and likely driven by a combination of hormonal and metabolic factors. Lipids have recently been implicated as inducers of cellular senescence in vitro and in vivo across human and animal models and more directly, the electrophilic products of lipid peroxidation have been shown in a number of systems to initiate the senescence program. This review summarizes recent research at the interface of lipid biology and senescence. The review will emphasize the types of electrophilic lipids that induce senescence and how lipid scavengers are used to alleviate senescence burden and combat age-related disease.

Oxidative phosphorylation and fatty acid oxidation in slow-aging mice

Oxidative metabolism declines with aging in humans leading to multiple metabolic ailments and subsequent inflammation. In mice, there is evidence of age-related suppression of fatty acid oxidation and oxidative phosphorylation in the liver, heart, and muscles. Many interventions that extend healthy lifespan of mice have been developed, including genetic, pharmacological, and dietary interventions. In this article, we review the literature on oxidative metabolism changes in response to those interventions. We also discuss the molecular pathways that mediate those changes, and their potential as targets for future longevity interventions.

The mitochondrial-targeted peptide therapeutic elamipretide improves cardiac and skeletal muscle function during aging without detectable changes in tissue epigenetic or transcriptomic age

Aging-related decreases in cardiac and skeletal muscle function are strongly associated with various comorbidities. Elamipretide (ELAM), a novel mitochondrial-targeted peptide, has demonstrated broad therapeutic efficacy in ameliorating disease conditions associated with mitochondrial dysfunction across both clinical and pre-clinical models. ELAM is proposed to restore mitochondrial bioenergetic function by stabilizing inner membrane structure and increasing oxidative phosphorylation coupling and efficiency. Although ELAM treatment effectively attenuates physiological declines in multiple tissues in rodent aging models, it remains unclear whether these functional improvements correlate with favorable changes in molecular biomarkers of aging. Herein, we investigated the impact of 8-week ELAM treatment on pre- and post- measures of C57BL/6J mice frailty, skeletal muscle, and cardiac muscle function, coupled with post-treatment assessments of biological age and affected molecular pathways. We found that health status, as measured by frailty index, cardiac strain, diastolic function, and skeletal muscle force are significantly diminished with age, with skeletal muscle force changing in a sex-dependent manner. Conversely, ELAM mitigated frailty accumulation and was able to partially reverse these declines, as evidenced by treatment-induced increases in cardiac strain and muscle fatigue resistance. Despite these improvements, we did not detect statistically significant changes in gene expression or DNA methylation profiles indicative of molecular reorganization or reduced biological age in most ELAM-treated groups. However, pathway analyses revealed that ELAM treatment showed pro-longevity shifts in gene expression such as upregulation of genes involved in fatty acid metabolism, mitochondrial translation and oxidative phosphorylation, and downregulation of inflammation. Together, these results indicate that ELAM treatment is effective at mitigating signs of sarcopenia and heart failure in an aging mouse model, but that these functional improvements occur independently of detectable changes in epigenetic and transcriptomic age. Thus, some age-related changes in function may be uncoupled from changes in molecular biological age.

Isotschimgine promotes lifespan, healthspan and neuroprotection of Caenorhabditis elegans via the activation of nuclear hormone receptors

Isotschimgine (ITG) is a bornane-type monoterpenoid derivative naturally occurring in genus Ferula plants and propolis. Its effects on aging and the underlying mechanisms are not yet well understood. This study employed Caenorhabditis elegans (C. elegans) as a model organism to evaluate the potential of ITG in extending lifespan, enhancing healthspan, and promoting neuroprotection, while exploring the underlying mechanisms involved. The results showed that ITG extended the lifespan and healthspan of C. elegans, significantly enhanced stress resistance and detoxification functions. Studies on mutants and qPCR data indicated that ITG-mediated lifespan extension was modulated by the insulin/IGF-1 signaling pathway and nuclear hormone receptors. Furthermore, ITG markedly increased stress-responsive genes, including daf-16 and its downstream genes sod-3 and hsp-16.2, as well as NHR downstream detoxification-related genes cyp35a1, cyp35b3, cyp35c1, gst-4, pgp-3 and pgp-13. Additionally, ITG alleviated β-amyloid-induced paralysis and behavioral dysfunction in transgenic C. elegans strains. The neuroprotective efficacy of ITG was weakened by RNAi knockdown of nuclear hormone receptors daf-12 and nhr-8. Overall, our study identifies ITG as a potential compound for promoting longevity and neuroprotection, mediated through nuclear hormone receptors.

Depletion of loss-of-function germline mutations in centenarians reveals longevity genes

While previous studies identified common genetic variants associated with longevity in centenarians, the role of the rare loss-of-function (LOF) mutation burden remains largely unexplored. Here, we investigated the burden of rare LOF mutations in Ashkenazi Jewish individuals from the Longevity Genes Project and LonGenity study cohorts using whole-exome sequencing data. We found that centenarians had a significantly lower burden (11-22%) of LOF mutations compared to controls. Similar effects were also observed in their offspring. Gene-level burden analysis identified 35 genes with depleted LOF mutations in centenarians, with 14 of these validated in the UK Biobank. Mendelian randomization and multi-omic analyses on these genes identified RGP1, PCNX2, and ANO9 as longevity genes with consistent causal effects on multiple aging-related traits and altered expression during aging. Our findings suggest that a protective genetic background, characterized by a reduced burden of damaging variants, contributes to exceptional longevity, likely acting in concert with specific protective variants to promote healthy aging.

Crocetin Delays Brain and Body Aging by Increasing Cellular Energy Levels in Aged C57BL/6J Mice

Aging is usually accompanied by mitochondrial dysfunction, reduced energy levels, and cell death in the brain and other tissues. Mitochondria play a crucial role in maintaining cellular energy through oxidative phosphorylation (OXPHOS). However, OXPHOS is impaired as the mitochondrial oxygen supply decreases with age. We explored whether pharmacologically increased oxygen diffusion by crocetin can restore OXPHOS and help delay the aging of the brain and other vital organs. We found that aged mice treated with crocetin for four months displayed significantly improved memory behavior, neuromuscular coordination, and ATP and NAD+ levels in the brain and other vital organs, leading to an increased median life span. The transcriptomic analysis of hippocampi from crocetin-treated mice revealed that enhanced brain energy level was caused by the upregulation of genes linked to OXPHOS, and their expression was close to that in young mice. The chronic treatment of aged astrocytes also showed improved mitochondrial membrane potential and energy state of the cells. Moreover, chronic treatment with crocetin did not cause any oxidative stress. Our data suggest that restoring OXPHOS and the normal energy state of the cell can delay aging and enhance longevity. Therefore, molecules such as crocetin should be further explored to treat age-related diseases.

Characterizing phenotypic data of Peromyscus leucopus compared to C57BL/6J Mus musculus and diversity outbred (DO) Mus musculus

Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.

Age-associated clonal B cells drive B cell lymphoma in mice

Although cancer is an age-related disease, how the processes of aging contribute to cancer progression is not well understood. In this study, we uncovered how mouse B cell lymphoma develops as a consequence of a naturally aged system. We show here that this malignancy is associated with an age-associated clonal B cell (ACBC) population that likely originates from age-associated B cells. Driven by c-Myc activation, promoter hypermethylation and somatic mutations, IgM+ ACBCs clonally expand independently of germinal centers and show increased biological age. ACBCs become self-sufficient and support malignancy when transferred into young recipients. Inhibition of mTOR or c-Myc in old mice attenuates pre-malignant changes in B cells during aging. Although the etiology of mouse and human B cell lymphomas is considered distinct, epigenetic changes in transformed mouse B cells are enriched for changes observed in human B cell lymphomas. Together, our findings characterize the spontaneous progression of cancer during aging through both cell-intrinsic and microenvironmental changes and suggest interventions for its prevention.

High-dimensional Ageome Representations of Biological Aging across Functional Modules

The aging process involves numerous molecular changes that lead to functional decline and increased disease and mortality risk. While epigenetic aging clocks have shown accuracy in predicting biological age, they typically provide single estimates for the samples and lack mechanistic insights. In this study, we challenge the paradigm that aging can be sufficiently described with a single biological age estimate. We describe Ageome, a computational framework for measuring the epigenetic age of thousands of molecular pathways simultaneously in mice and humans. Ageome is based on the premise that an organism's overall biological age can be approximated by the collective ages of its functional modules, which may age at different rates and have different biological ages. We show that, unlike conventional clocks, Ageome provides a high-dimensional representation of biological aging across cellular functions, enabling comprehensive assessment of aging dynamics within an individual, in a population, and across species. Application of Ageome to longevity intervention models revealed distinct patterns of pathway-specific age deceleration. Notably, cell reprogramming, while rejuvenating cells, also accelerated aging of some functional modules. When applied to human cohorts, Ageome demonstrated heterogeneity in predictive power for mortality risk, and some modules showed better performance in predicting the onset of age-related diseases, especially cancer, compared to existing clocks. Together, the Ageome framework offers a comprehensive and interpretable approach for assessing aging, providing insights into mechanisms and targets for intervention.

Cysteine depletion triggers adipose tissue thermogenesis and weight-loss

Dietary interventions such as caloric restriction (CR)1 and methionine restriction2 that prolong lifespan induce the 'browning' of white adipose tissue (WAT), an adaptive metabolic response that increases heat production to maintain health3,4. However, how diet influences adipose browning and metabolic health is unclear. Here, we identified that weight-loss induced by CR in humans5 reduces cysteine concentration in WAT suggesting depletion of this amino-acid may be involved in metabolic benefits of CR. To investigate the role of cysteine on organismal metabolism, we created a cysteine-deficiency mouse model in which dietary cysteine was eliminated and cystathionine γ-lyase (CTH)6, the enzyme that synthesizes cysteine was conditionally deleted. Using this animal model, we found that systemic cysteine-depletion causes drastic weight-loss with increased fat utilization and browning of adipose tissue. The restoration of dietary cysteine in cysteine-deficient mice rescued weight loss together with reversal of adipose browning and increased food-intake in an on-demand fashion. Mechanistically, cysteine deficiency induced browning and weight loss is dependent on sympathetic nervous system derived noradrenaline signaling via β3-adrenergic-receptors and does not require UCP1. Therapeutically, in high-fat diet fed obese mice, one week of cysteine-deficiency caused 30% weight-loss and reversed inflammation. These findings thus establish that cysteine is essential for organismal metabolism as removal of cysteine in the host triggers adipose browning and rapid weight loss.

Maternal α-casein deficiency extends the lifespan of offspring and programmes their body composition

Early nutrition has significant effects on physiological outcomes during adult life. We have analysed the effect of maternal α-casein (CSN1S1) deficiency on the physiological fate of dams and their offspring. α-casein deficiency reduces maternal milk protein concentration by more than 50% and attenuates the growth of pups to 27% (p < 0.001) of controls at the point of weaning. This is associated with a permanent reduction in adult body weight (- 31% at 25 weeks). Offspring nursed by α-casein deficient dams showed a significantly increased lifespan (+ 20%, χ2: 10.6; p = 0.001). Liver transcriptome analysis of offspring nursed by α-casein deficient dams at weaning revealed gene expression patterns similar to those found in dwarf mice (reduced expression of somatotropic axis signalling genes, increased expression of xenobiotic metabolism genes). In adult mice, the expression of somatotropic axis genes returned to control levels. This demonstrates that, in contrast to dwarf mice, attenuation of the GH-IGF signalling axis in offspring nursed by α-casein deficient dams is transient, while the changes in body size and lifespan are permanent. Offspring nursed by α-casein deficient dams showed permanent changes in body composition. Absolute and relative adipose tissue weights (p < 0.05), the percentage of body fat (p < 0.001) as well as adipocyte size in epididymal white adipose tissue are all reduced. Serum leptin levels were 25% of those found in control mice (p < 0.001). Liver lipid content and lipid composition were significantly altered in response to postnatal nutrition. This demonstrates the nutrition in early life programmes adult lipid metabolism, body composition and lifespan.

Relationship between Hypoxia and Hypercapnia Tolerance and Life Expectancy

The review discusses the potential relationship between hypoxia resistance and longevity, the influence of carbon dioxide on the mechanisms of aging of the mammalian organism, and intermittent hypercapnic-hypoxic effects on the signaling pathways of aging mechanisms. In the article, we focused on the potential mechanisms of the gero-protective efficacy of carbon dioxide when combined with hypoxia. The review summarizes the possible influence of intermittent hypoxia and hypercapnia on aging processes in the nervous system. We considered the perspective variants of the application of hypercapnic-hypoxic influences for achieving active longevity and the prospects for the possibilities of developing hypercapnic-hypoxic training methods.

Hydrogen sulfide and its role in female reproduction

Hydrogen sulfide (H2S) is a gaseous signaling molecule produced in the body by three enzymes: cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST). H2S is crucial in various physiological processes associated with female mammalian reproduction. These include estrus cycle, oocyte maturation, oocyte aging, ovulation, embryo transport and early embryo development, the development of the placenta and fetal membranes, pregnancy, and the initiation of labor. Despite the confirmed presence of H2S-producing enzymes in all female reproductive tissues, as described in this review, the exact mechanisms of H2S action in these tissues remain in most cases unclear. Therefore, this review aims to summarize the knowledge about the presence and effects of H2S in these tissues and outline possible signaling pathways that mediate these effects. Understanding these pathways may lead to the development of new therapeutic strategies in the field of women's health and perinatal medicine.

The killifish germline regulates longevity and somatic repair in a sex-specific manner

Classical evolutionary theories propose tradeoffs among reproduction, damage repair and lifespan. However, the specific role of the germline in shaping vertebrate aging remains largely unknown. In this study, we used the turquoise killifish (Nothobranchius furzeri) to genetically arrest germline development at discrete stages and examine how different modes of infertility impact life history. We first constructed a comprehensive single-cell gonadal atlas, providing cell-type-specific markers for downstream phenotypic analysis. We show here that germline depletion-but not arresting germline differentiation-enhances damage repair in female killifish. Conversely, germline-depleted males instead showed an extension in lifespan and rejuvenated metabolic functions. Through further transcriptomic analysis, we highlight enrichment of pro-longevity pathways and genes in germline-depleted male killifish and demonstrate functional conservation of how these factors may regulate longevity in germline-depleted Caenorhabditis elegans. Our results, therefore, demonstrate that different germline manipulation paradigms can yield pronounced sexually dimorphic phenotypes, implying alternative responses to classical evolutionary tradeoffs.

Mulberrin extends lifespan in Caenorhabditis elegans through detoxification function

Mulberrin, a naturally occurring flavone found in mulberry and Romulus Mori, exhibits diverse biological functions. Here, we showed that mulberrin extended both the lifespan and healthspan in C. elegans. Moreover, mulberrin increased the worms' resistance to toxicants and activated the expression of detoxification genes. The longevity-promoting effect of mulberrin was attenuated in nuclear hormone receptor (NHR) homologous nhr-8 and daf-12 mutants, indicating that the lifespan extending effects of mulberrin in C. elegans may depend on nuclear hormone receptors NHR-8/DAF-12. Further analyses revealed the potential associations between the longevity effects of mulberrin and the insulin/insulin-like growth factor signaling (IIS) and adenosine 5'-monophosphate-activated protein kinase (AMPK) pathways. Together, our findings suggest that mulberrin may prolong lifespan and healthspan by activating detoxification functions mediated by nuclear receptors.

A disease similarity approach identifies short-lived Niemann-Pick type C disease mice with accelerated brain aging as a novel mouse model for Alzheimer's disease and aging research

Since its first description in 1906 by Dr. Alois Alzheimer, Alzheimer's disease (AD) has been the most common type of dementia. Initially thought to be caused by age-associated accumulation of plaques, in recent years, research has increasingly associated AD with lysosomal storage and metabolic disorders, and the explanation of its pathogenesis has shifted from amyloid and tau accumulation to oxidative stress and impaired lipid and glucose metabolism aggravated by hypoxic conditions. However, the underlying mechanisms linking those cellular processes and conditions to disease progression have yet to be defined. Here, we applied a disease similarity approach to identify unknown molecular targets of AD by using transcriptomic data from congenital diseases known to increase AD risk, namely Down Syndrome, Niemann Pick Disease Type C (NPC), and Mucopolysaccharidoses I. We uncovered common pathways, hub genes, and miRNAs across in vitro and in vivo models of these diseases as potential molecular targets for neuroprotection and amelioration of AD pathology, many of which have never been associated with AD. We then investigated common molecular alterations in brain samples from an NPC disease mouse model by juxtaposing them with brain samples of both human and mouse models of AD. Detailed phenotypic and molecular analyses revealed that the NPC mut mouse model can serve as a potential short-lived in vivo model for AD research and for understanding molecular factors affecting brain aging. This research represents the first comprehensive approach to congenital disease association with neurodegeneration and a new perspective on AD research while highlighting shortcomings and lack of correlation in diverse in vitro models. Considering the lack of an AD mouse model that recapitulates the physiological hallmarks of brain aging, the characterization of a short-lived NPC mouse model will further accelerate the research in these fields and offer a unique model for understanding the molecular mechanisms of AD from a perspective of accelerated brain aging.

The killifish germline regulates longevity and somatic repair in a sex-specific manner

Classical evolutionary theories propose tradeoffs between reproduction, damage repair, and lifespan. However, the specific role of the germline in shaping vertebrate aging remains largely unknown. Here, we use the turquoise killifish ( N. furzeri ) to genetically arrest germline development at discrete stages, and examine how different modes of infertility impact life-history. We first construct a comprehensive single-cell gonadal atlas, providing cell-type-specific markers for downstream phenotypic analysis. Next, we show that germline depletion - but not arresting germline differentiation - enhances damage repair in female killifish. Conversely, germline-depleted males instead showed an extension in lifespan and rejuvenated metabolic functions. Through further transcriptomic analysis, we highlight enrichment of pro-longevity pathways and genes in germline-depleted male killifish and demonstrate functional conservation of how these factors may regulate longevity in germline-depleted C. elegans . Our results therefore demonstrate that different germline manipulation paradigms can yield pronounced sexually dimorphic phenotypes, implying alternative responses to classical evolutionary tradeoffs.

Geroprotective interventions converge on gene expression programs of reduced inflammation and restored fatty acid metabolism

Understanding the mechanisms of geroprotective interventions is central to aging research. We compare four prominent interventions: senolysis, caloric restriction, in vivo partial reprogramming, and heterochronic parabiosis. Using published mice transcriptomic data, we juxtapose these interventions against normal aging. We find a gene expression program common to all four interventions, in which inflammation is reduced and several metabolic processes, especially fatty acid metabolism, are increased. Normal aging exhibits the inverse of this signature across multiple organs and tissues. A similar inverse signature arises in three chronic inflammation disease models in a non-aging context, suggesting that the shift in metabolism occurs downstream of inflammation. Chronic inflammation is also shown to accelerate transcriptomic age. We conclude that a core mechanism of geroprotective interventions acts through the reduction of inflammation with downstream effects that restore fatty acid metabolism. This supports the notion of directly targeting genes associated with these pathways to mitigate age-related deterioration.

Proteomic changes induced by longevity-promoting interventions in mice

Using mouse models and high-throughput proteomics, we conducted an in-depth analysis of the proteome changes induced in response to seven interventions known to increase mouse lifespan. This included two genetic mutations, a growth hormone receptor knockout (GHRKO mice) and a mutation in the Pit-1 locus (Snell dwarf mice), four drug treatments (rapamycin, acarbose, canagliflozin, and 17α-estradiol), and caloric restriction. Each of the interventions studied induced variable changes in the concentrations of proteins across liver, kidney, and gastrocnemius muscle tissue samples, with the strongest responses in the liver and limited concordance in protein responses across tissues. To the extent that these interventions promote longevity through common biological mechanisms, we anticipated that proteins associated with longevity could be identified by characterizing shared responses across all or multiple interventions. Many of the proteome alterations induced by each intervention were distinct, potentially implicating a variety of biological pathways as being related to lifespan extension. While we found no protein that was affected similarly by every intervention, we identified a set of proteins that responded to multiple interventions. These proteins were functionally diverse but tended to be involved in peroxisomal oxidation and metabolism of fatty acids. These results provide candidate proteins and biological mechanisms related to enhancing longevity that can inform research on therapeutic approaches to promote healthy aging.

Time is ticking faster for long genes in aging

Recent studies of aging organisms have identified a systematic phenomenon, characterized by a negative correlation between gene length and their expression in various cell types, species, and diseases. We term this phenomenon gene-length-dependent transcription decline (GLTD) and suggest that it may represent a bottleneck in the transcription machinery and thereby significantly contribute to aging as an etiological factor. We review potential links between GLTD and key aging processes such as DNA damage and explore their potential in identifying disease modification targets. Notably, in Alzheimer's disease, GLTD spotlights extremely long synaptic genes at chromosomal fragile sites (CFSs) and their vulnerability to postmitotic DNA damage. We suggest that GLTD is an integral element of biological aging.

A torpor-like state (TLS) in mice slows blood epigenetic aging and prolongs healthspan

Torpor and hibernation are extreme physiological adaptations of homeotherms associated with pro-longevity effects. Yet the underlying mechanisms of how torpor affects aging, and whether hypothermic and hypometabolic states can be induced to slow aging and increase health span, remain unknown. We demonstrate that the activity of a spatially defined neuronal population in the avMLPA, which has previously been identified as a torpor-regulating brain region, is sufficient to induce a torpor like state (TLS) in mice. Prolonged induction of TLS slows epigenetic aging across multiple tissues and improves health span. We isolate the effects of decreased metabolic rate, long-term caloric restriction, and decreased core body temperature (Tb) on blood epigenetic aging and find that the pro-longevity effect of torpor-like states is mediated by decreased Tb. Taken together, our findings provide novel mechanistic insight into the pro-longevity effects of torpor and hibernation and support the growing body of evidence that Tb is an important mediator of aging processes.

Multi-omics characterization of partial chemical reprogramming reveals evidence of cell rejuvenation

Partial reprogramming by cyclic short-term expression of Yamanaka factors holds promise for shifting cells to younger states and consequently delaying the onset of many diseases of aging. However, the delivery of transgenes and potential risk of teratoma formation present challenges for in vivo applications. Recent advances include the use of cocktails of compounds to reprogram somatic cells, but the characteristics and mechanisms of partial cellular reprogramming by chemicals remain unclear. Here, we report a multi-omics characterization of partial chemical reprogramming in fibroblasts from young and aged mice. We measured the effects of partial chemical reprogramming on the epigenome, transcriptome, proteome, phosphoproteome, and metabolome. At the transcriptome, proteome, and phosphoproteome levels, we saw widescale changes induced by this treatment, with the most notable signature being an upregulation of mitochondrial oxidative phosphorylation. Furthermore, at the metabolome level, we observed a reduction in the accumulation of aging-related metabolites. Using both transcriptomic and epigenetic clock-based analyses, we show that partial chemical reprogramming reduces the biological age of mouse fibroblasts. We demonstrate that these changes have functional impacts, as evidenced by changes in cellular respiration and mitochondrial membrane potential. Taken together, these results illuminate the potential for chemical reprogramming reagents to rejuvenate aged biological systems and warrant further investigation into adapting these approaches for in vivo age reversal.

Short-term hypercaloric carbohydrate loading increases surgical stress resilience by inducing FGF21

Dietary restriction promotes resistance to surgical stress in multiple organisms. Counterintuitively, current medical protocols recommend short-term carbohydrate-rich drinks (carbohydrate loading) prior to surgery, part of a multimodal perioperative care pathway designed to enhance surgical recovery. Despite widespread clinical use, preclinical and mechanistic studies on carbohydrate loading in surgical contexts are lacking. Here we demonstrate in ad libitum-fed mice that liquid carbohydrate loading for one week drives reductions in solid food intake, while nearly doubling total caloric intake. Similarly, in humans, simple carbohydrate intake is inversely correlated with dietary protein intake. Carbohydrate loading-induced protein dilution increases expression of hepatic fibroblast growth factor 21 (FGF21) independent of caloric intake, resulting in protection in two models of surgical stress: renal and hepatic ischemia-reperfusion injury. The protection is consistent across male, female, and aged mice. In vivo, amino acid add-back or genetic FGF21 deletion blocks carbohydrate loading-mediated protection from ischemia-reperfusion injury. Finally, carbohydrate loading induction of FGF21 is associated with the induction of the canonical integrated stress response (ATF3/4, NF-kB), and oxidative metabolism (PPARγ). Together, these data support carbohydrate loading drinks prior to surgery and reveal an essential role of protein dilution via FGF21.

Diet-Modifiable Redox Alterations in Ageing and Cancer

With ageing comes some of life's best and worst moments. Those lucky enough to live out into the seventh, eighth, and nineth decades and perhaps beyond have more opportunities to experience the wonders and joys of the world. As the world's population shifts towards more and more of these individuals, this is something to be celebrated. However, it is not without negative consequences. Advanced age also ushers in health decline and the burden of non-communicable diseases such as cancer, heart disease, stroke, and organ function decay. Thus, alleviating or at least dampening the severity of ageing as a whole, as well as these individual age-related disorders will enable the improvement in lifespan and healthspan. In the following chapter, we delve into hypothesised causes of ageing and experimental interventions that can be taken to slow their progression. We also highlight cellular and subcellular mechanisms of ageing with a focus on protein thiol oxidation and posttranslational modifications that impact cellular homeostasis and the advent and progression of ageing-related cancers. By having a better understanding of the mechanisms of ageing, we can hopefully develop effective, safe, and efficient therapeutic modalities that can be used prophylactically and/or concurrent to the onset of ageing.

Downregulation of mitochondrial metabolism is a driver for fast skeletal muscle loss during mouse aging

Skeletal muscle aging is characterized by the loss of muscle mass, strength and function, mainly attributed to the atrophy of glycolytic fibers. Underlying mechanisms driving the skeletal muscle functional impairment are yet to be elucidated. To unbiasedly uncover its molecular mechanisms, we recurred to gene expression and metabolite profiling in a glycolytic muscle, Extensor digitorum longus (EDL), from young and aged C57BL/6JRj mice. Employing multi-omics approaches we found that the main age-related changes are connected to mitochondria, exhibiting a downregulation in mitochondrial processes. Consistent is the altered mitochondrial morphology. We further compared our mouse EDL aging signature with human data from the GTEx database, reinforcing the idea that our model may recapitulate muscle loss in humans. We are able to show that age-related mitochondrial downregulation is likely to be detrimental, as gene expression signatures from commonly used lifespan extending interventions displayed the opposite direction compared to our EDL aging signature.

Senolytic therapy alleviates physiological human brain aging and COVID-19 neuropathology

Aging is a major risk factor for neurodegenerative diseases, and coronavirus disease 2019 (COVID-19) is linked to severe neurological manifestations. Senescent cells contribute to brain aging, but the impact of virus-induced senescence on neuropathologies is unknown. Here we show that senescent cells accumulate in aged human brain organoids and that senolytics reduce age-related inflammation and rejuvenate transcriptomic aging clocks. In postmortem brains of patients with severe COVID-19 we observed increased senescent cell accumulation compared with age-matched controls. Exposure of human brain organoids to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induced cellular senescence, and transcriptomic analysis revealed a unique SARS-CoV-2 inflammatory signature. Senolytic treatment of infected brain organoids blocked viral replication and prevented senescence in distinct neuronal populations. In human-ACE2-overexpressing mice, senolytics improved COVID-19 clinical outcomes, promoted dopaminergic neuron survival and alleviated viral and proinflammatory gene expression. Collectively our results demonstrate an important role for cellular senescence in driving brain aging and SARS-CoV-2-induced neuropathology, and a therapeutic benefit of senolytic treatments.

Multi-omics characterization of partial chemical reprogramming reveals evidence of cell rejuvenation

Partial reprogramming by cyclic short-term expression of Yamanaka factors holds promise for shifting cells to younger states and consequently delaying the onset of many diseases of aging. However, the delivery of transgenes and potential risk of teratoma formation present challenges for in vivo applications. Recent advances include the use of cocktails of compounds to reprogram somatic cells, but the characteristics and mechanisms of partial cellular reprogramming by chemicals remain unclear. Here, we report a multi-omics characterization of partial chemical reprogramming in fibroblasts from young and aged mice. We measured the effects of partial chemical reprogramming on the epigenome, transcriptome, proteome, phosphoproteome, and metabolome. At the transcriptome, proteome, and phosphoproteome levels, we saw widescale changes induced by this treatment, with the most notable signature being an upregulation of mitochondrial oxidative phosphorylation. Furthermore, at the metabolome level, we observed a reduction in the accumulation of aging-related metabolites. Using both transcriptomic and epigenetic clock-based analyses, we show that partial chemical reprogramming reduces the biological age of mouse fibroblasts. We demonstrate that these changes have functional impacts, as evidenced by changes in cellular respiration and mitochondrial membrane potential. Taken together, these results illuminate the potential for chemical reprogramming reagents to rejuvenate aged biological systems and warrant further investigation into adapting these approaches for in vivo age reversal.

A NRF2-induced secretory phenotype activates immune surveillance to remove irreparably damaged cells

While it is well established that the KEAP1-NRF2 pathway regulates the main inducible cellular response to oxidative stress, this cytoprotective function of NRF2 could become deleterious to the host if it confers survival onto irreparably damaged cells. In this regard, we have found that in diseased states, NRF2 promotes the transcriptional activation of a specific subset of the senescence-associated secretory phenotype (SASP) gene program, which we have named the NRF2-induced secretory phenotype (NISP). In two models of hepatic disease using Pten::Keap1 and Keap1::Atg7 double knockout mice, we found that the NISP functions in the liver to recruit CCR2 expressing monocytes, which function as immune system effector cells to directly remove the damaged cells. Through activation of this immune surveillance pathway, in non-transformed cells, NRF2 functions as a tumour suppressor to mitigate the long-term survival of damaged cells which otherwise would be detrimental for host survival. This pathway represents the final stage of the oxidative stress response, as it allows cells to be safely removed if the macromolecular damage caused by the original stressor is so extensive that it is beyond the repair capacity of the cell.

Coordinated transcriptional upregulation of oxidative metabolism proteins in long-lived endocrine mutant mice

Caloric restriction (CR), which extends lifespan in rodents, leads to increased hepatic fatty acid β-oxidation and oxidative phosphorylation (OXPHOS), with parallel changes in proteins and their mRNAs. Genetic mutants that extend lifespan, including growth hormone receptor knockout (GHRKO) and Snell dwarf (SD) mice, have lower respiratory quotient, suggesting increased reliance on fatty acid oxidation, but the molecular mechanism(s) of this metabolic shift have not yet been worked out. Here we show that both GHRKO and SD mice have significantly higher mRNA and protein levels of enzymes involved in mitochondrial and peroxisomal fatty acid β-oxidation. In addition, multiple subunits of OXPHOS complexes I-IV are upregulated in GHRKO and SD livers, and Complex V subunit ATP5a is upregulated in liver of GHRKO mice. Expression of these genes is regulated by a group of nuclear receptors and transcription factors including peroxisome proliferator-activated receptors (PPARs) and estrogen-related receptors (ERRs). We found that levels of these nuclear receptors and their co-activator PGC-1α were unchanged or downregulated in liver of GHRKO and SD mice. In contrast, NCOR1, a co-repressor for the same receptors, was significantly downregulated in the two long-lived mouse models, suggesting a plausible mechanism for the changes in FAO and OXPHOS proteins. Hepatic levels of HDAC3, a co-factor for NCOR1 transcriptional repression, were also downregulated. The role of NCOR1 is well established in the contexts of cancer and metabolic disease, but may provide new mechanistic insights into metabolic control in long-lived mouse models.

Increased hyaluronan by naked mole-rat Has2 improves healthspan in mice

Abundant high-molecular-mass hyaluronic acid (HMM-HA) contributes to cancer resistance and possibly to the longevity of the longest-lived rodent-the naked mole-rat1,2. To study whether the benefits of HMM-HA could be transferred to other animal species, we generated a transgenic mouse overexpressing naked mole-rat hyaluronic acid synthase 2 gene (nmrHas2). nmrHas2 mice showed an increase in hyaluronan levels in several tissues, and a lower incidence of spontaneous and induced cancer, extended lifespan and improved healthspan. The transcriptome signature of nmrHas2 mice shifted towards that of longer-lived species. The most notable change observed in nmrHas2 mice was attenuated inflammation across multiple tissues. HMM-HA reduced inflammation through several pathways, including a direct immunoregulatory effect on immune cells, protection from oxidative stress and improved gut barrier function during ageing. These beneficial effects were conferred by HMM-HA and were not specific to the nmrHas2 gene. These findings demonstrate that the longevity mechanism that evolved in the naked mole-rat can be exported to other species, and open new paths for using HMM-HA to improve lifespan and healthspan.

Genetic perturbation of AMP biosynthesis extends lifespan and restores metabolic health in a naturally short-lived vertebrate

During aging, the loss of metabolic homeostasis drives a myriad of pathologies. A central regulator of cellular energy, the AMP-activated protein kinase (AMPK), orchestrates organismal metabolism. However, direct genetic manipulations of the AMPK complex in mice have, so far, produced detrimental phenotypes. Here, as an alternative approach, we alter energy homeostasis by manipulating the upstream nucleotide pool. Using the turquoise killifish, we mutate APRT, a key enzyme in AMP biosynthesis, and extend the lifespan of heterozygous males. Next, we apply an integrated omics approach to show that metabolic functions are rejuvenated in old mutants, which also display a fasting-like metabolic profile and resistance to high-fat diet. At the cellular level, heterozygous cells exhibit enhanced nutrient sensitivity, reduced ATP levels, and AMPK activation. Finally, lifelong intermittent fasting abolishes the longevity benefits. Our findings suggest that perturbing AMP biosynthesis may modulate vertebrate lifespan and propose APRT as a promising target for promoting metabolic health.

Multi-omic rejuvenation and life span extension on exposure to youthful circulation

Heterochronic parabiosis (HPB) is known for its functional rejuvenation effects across several mouse tissues. However, its impact on biological age and long-term health is unknown. Here we performed extended (3-month) HPB, followed by a 2-month detachment period of anastomosed pairs. Old detached mice exhibited improved physiological parameters and lived longer than control isochronic mice. HPB drastically reduced the epigenetic age of blood and liver based on several clock models using two independent platforms. Remarkably, this rejuvenation effect persisted even after 2 months of detachment. Transcriptomic and epigenomic profiles of anastomosed mice showed an intermediate phenotype between old and young, suggesting a global multi-omic rejuvenation effect. In addition, old HPB mice showed gene expression changes opposite to aging but akin to several life span-extending interventions. Altogether, we reveal that long-term HPB results in lasting epigenetic and transcriptome remodeling, culminating in the extension of life span and health span.

Lifespan-extending interventions induce consistent patterns of fatty acid oxidation in mouse livers

Aging manifests as progressive deteriorations in homeostasis, requiring systems-level perspectives to investigate the gradual molecular dysregulation of underlying biological processes. Here, we report systemic changes in the molecular regulation of biological processes under multiple lifespan-extending interventions. Differential Rank Conservation (DIRAC) analyses of mouse liver proteomics and transcriptomics data show that mechanistically distinct lifespan-extending interventions (acarbose, 17α-estradiol, rapamycin, and calorie restriction) generally tighten the regulation of biological modules. These tightening patterns are similar across the interventions, particularly in processes such as fatty acid oxidation, immune response, and stress response. Differences in DIRAC patterns between proteins and transcripts highlight specific modules which may be tightened via augmented cap-independent translation. Moreover, the systemic shifts in fatty acid metabolism are supported through integrated analysis of liver transcriptomics data with a mouse genome-scale metabolic model. Our findings highlight the power of systems-level approaches for identifying and characterizing the biological processes involved in aging and longevity.

Emerging Chemical Biology of Protein Persulfidation

Significance: Protein persulfidation (the formation of RSSH), an evolutionarily conserved oxidative posttranslational modification in which thiol groups in cysteine residues are converted into persulfides, has emerged as one of the main mechanisms through which hydrogen sulfide (H2S) conveys its signaling. Recent Advances: New methodological advances in persulfide labeling started unraveling the chemical biology of this modification and its role in (patho)physiology. Some of the key metabolic enzymes are regulated by persulfidation. RSSH levels are important for the cellular defense against oxidative injury, and they decrease with aging, leaving proteins vulnerable to oxidative damage. Persulfidation is dysregulated in many diseases. Critical Issues: A relatively new field of signaling by protein persulfidation still has many unanswered questions: the mechanism(s) of persulfide formation and transpersulfidation and the identification of "protein persulfidases," the improvement of methods to monitor RSSH changes and identify protein targets, and understanding the mechanisms through which this modification controls important (patho)physiological functions. Future Directions: Deep mechanistic studies using more selective and sensitive RSSH labeling techniques will provide high-resolution structural, functional, quantitative, and spatiotemporal information on RSSH dynamics and help with better understanding how H2S-derived protein persulfidation affects protein structure and function in health and disease. This knowledge could pave the way for targeted drug design for a wide variety of pathologies. Antioxid. Redox Signal. 39, 19-39.

[WITHDRAWN] Activation of transsulfuration pathway to maintain cysteine is a thermogenic checkpoint for the conservation of energy

The authors have requested that this preprint be removed from Research Square.

Dietary restriction mitigates the age-associated decline in mouse B cell receptor repertoire diversity

Aging impairs the capacity to respond to novel antigens, reducing immune protection against pathogens and vaccine efficacy. Dietary restriction (DR) extends life- and health span in diverse animals. However, little is known about the capacity of DR to combat the decline in immune function. Here, we study the changes in B cell receptor (BCR) repertoire during aging in DR and control mice. By sequencing the variable region of the BCR heavy chain in the spleen, we show that DR preserves diversity and attenuates the increase in clonal expansions throughout aging. Remarkably, mice starting DR in mid-life have repertoire diversity and clonal expansion rates indistinguishable from chronic DR mice. In contrast, in the intestine, these traits are unaffected by either age or DR. Reduced within-individual B cell repertoire diversity and increased clonal expansions are correlated with higher morbidity, suggesting a potential contribution of B cell repertoire dynamics to health during aging.

Distinct longevity mechanisms across and within species and their association with aging

Lifespan varies within and across species, but the general principles of its control remain unclear. Here, we conducted multi-tissue RNA-seq analyses across 41 mammalian species, identifying longevity signatures and examining their relationship with transcriptomic biomarkers of aging and established lifespan-extending interventions. An integrative analysis uncovered shared longevity mechanisms within and across species, including downregulated Igf1 and upregulated mitochondrial translation genes, and unique features, such as distinct regulation of the innate immune response and cellular respiration. Signatures of long-lived species were positively correlated with age-related changes and enriched for evolutionarily ancient essential genes, involved in proteolysis and PI3K-Akt signaling. Conversely, lifespan-extending interventions counteracted aging patterns and affected younger, mutable genes enriched for energy metabolism. The identified biomarkers revealed longevity interventions, including KU0063794, which extended mouse lifespan and healthspan. Overall, this study uncovers universal and distinct strategies of lifespan regulation within and across species and provides tools for discovering longevity interventions.

Pregnane X receptor agonist nomilin extends lifespan and healthspan in preclinical models through detoxification functions

Citrus fruit has long been considered a healthy food, but its role and detailed mechanism in lifespan extension are not clear. Here, by using the nematode C. elegans, we identified that nomilin, a bitter-taste limoloid that is enriched in citrus, significantly extended the animals' lifespan, healthspan, and toxin resistance. Further analyses indicate that this ageing inhibiting activity depended on the insulin-like pathway DAF-2/DAF-16 and nuclear hormone receptors NHR-8/DAF-12. Moreover, the human pregnane X receptor (hPXR) was identified as the mammalian counterpart of NHR-8/DAF-12 and X-ray crystallography showed that nomilin directly binds with hPXR. The hPXR mutations that prevented nomilin binding blocked the activity of nomilin both in mammalian cells and in C. elegans. Finally, dietary nomilin supplementation improved healthspan and lifespan in D-galactose- and doxorubicin-induced senescent mice as well as in male senescence accelerated mice prone 8 (SAMP8) mice, and induced a longevity gene signature similar to that of most longevity interventions in the liver of bile-duct-ligation male mice. Taken together, we identified that nomilin may extend lifespan and healthspan in animals via the activation of PXR mediated detoxification functions.

Extracellular Matrix Dynamics as an Emerging yet Understudied Hallmark of Aging and Longevity

The biomechanical properties of extracellular matrices (ECM) and their consequences for cellular homeostasis have recently emerged as a driver of aging. Here we review the age-dependent deterioration of ECM in the context of our current understanding of the aging processes. We discuss the reciprocal interactions of longevity interventions with ECM remodeling. And the relevance of ECM dynamics captured by the matrisome and the matreotypes associated with health, disease, and longevity. Furthermore, we highlight that many established longevity compounds promote ECM homeostasis. A large body of evidence for the ECM to qualify as a hallmark of aging is emerging, and the data in invertebrates is promising. However, direct experimental proof that activating ECM homeostasis is sufficient to slow aging in mammals is lacking. We conclude that further research is required and anticipate that a conceptual framework for ECM biomechanics and homeostasis will provide new strategies to promote health during aging.

Biological age is increased by stress and restored upon recovery

Aging is classically conceptualized as an ever-increasing trajectory of damage accumulation and loss of function, leading to increases in morbidity and mortality. However, recent in vitro studies have raised the possibility of age reversal. Here, we report that biological age is fluid and exhibits rapid changes in both directions. At epigenetic, transcriptomic, and metabolomic levels, we find that the biological age of young mice is increased by heterochronic parabiosis and restored following surgical detachment. We also identify transient changes in biological age during major surgery, pregnancy, and severe COVID-19 in humans and/or mice. Together, these data show that biological age undergoes a rapid increase in response to diverse forms of stress, which is reversed following recovery from stress. Our study uncovers a new layer of aging dynamics that should be considered in future studies. The elevation of biological age by stress may be a quantifiable and actionable target for future interventions.