Regulation of the one carbon folate cycle as a shared metabolic signature of longevity

Nanoparticles mediated folic acid enrichment

Folate is an essential component of many metabolic processes, and folate deficiency is known to cause various disorders. Folate and folic acid, a synthetic and chemically stable form of folate, enriched diet are typically used to overcome this deficiency. Folic acid and folate however, are susceptible to harsh environment and folates enrichment using nanoparticles is an intensively studied strategy in food industry. This review highlights the current methods and types of matrices utilized to develop folic acid/folate carrying nanoparticles. The folic acid/folate loaded nanoparticles prevent cargo degradation during gut absorption and under harsh food processing conditions including, high temperatures, UV light, and autoclaving. The data demonstrates that nanofortifcation of folates using proteins and biopolymers effectively enhances the bioavailability of the cargo. The encapsulation of folic acid in biopolymers by emulsion, spray drying and ionic gelation represent simplistic methods that can be easily scaled up with applications in food industry.

Late-life dietary folate restriction reduces biosynthesis without compromising healthspan in mice

Folate is a vitamin required for cell growth and is present in fortified foods in the form of folic acid to prevent congenital abnormalities. The impact of low-folate status on life-long health is poorly understood. We found that limiting folate levels with the folate antagonist methotrexate increased the lifespan of yeast and worms. We then restricted folate intake in aged mice and measured various health metrics, metabolites, and gene expression signatures. Limiting folate intake decreased anabolic biosynthetic processes in mice and enhanced metabolic plasticity. Despite reduced serum folate levels in mice with limited folic acid intake, these animals maintained their weight and adiposity late in life, and we did not observe adverse health outcomes. These results argue that the effectiveness of folate dietary interventions may vary depending on an individual's age and sex. A higher folate intake is advantageous during the early stages of life to support cell divisions needed for proper development. However, a lower folate intake later in life may result in healthier aging.

Exposure to prenatal excess or imbalanced micronutrients leads to long-term perturbations in one-carbon metabolism, trimethylamine-N-oxide and DNA methylation in Wistar rat offspring

Prenatal multivitamins, including folic acid, are commonly consumed in excess, whereas choline, an essential nutrient and an important source of labile methyl groups, is underconsumed. Here, we characterized profiles of one-carbon metabolism and related pathways and patterns of DNA methylation in offspring exposed to excess or imbalanced micronutrients prenatally. Pregnant Wistar rats were fed either recommended 1× vitamins (RV), high 10× vitamins (HV), high 10× folic acid with recommended choline (HFolRC), or high 10× folic acid with no choline (HFolNC). Offspring were weaned to a high-fat diet for 12 weeks. Circulating metabolites were analyzed with a focus on the hypothalamus, an area known to be under epigenetic regulation. HV, HFolRC, and HFolNC males had higher body weight (BW) and lower plasma choline and methionine consistent with lower hypothalamic S-adenosylmethionine (SAM):S-adenosylhomocysteine (SAH) and global DNA methylation compared with RV. HV and HFolNC females had higher BW and lower plasma 5-methyltetrahydrofolate and methionine consistent with lower hypothalamic global DNA methylation compared with RV. Plasma dimethylglycine (DMG) and methionine were higher as with hypothalamic SAM:SAH and global DNA methylation in HFolRC females without changes in BW compared with RV. Plasma trimethylamine and trimethylamine-N-oxide were higher in males but lower in females from HFolRC compared with RV. Network modeling revealed a link between the folate-dependent pathway and SAH, with most connections through DMG. Final BW was negatively correlated with choline, DMG, and global DNA methylation. In conclusion, prenatal intake of excess or imbalanced micronutrients induces distinct metabolic and epigenetic perturbations in offspring that reflect long-term nutritional programming of health.

Multi-Omics Integrative Analysis to Reveal the Impacts of Shewanella algae on the Development and Lifespan of Marine Nematode Litoditis marina

Understanding how habitat bacteria affect animal development, reproduction, and aging is essential for deciphering animal biology. Our recent study showed that Shewanella algae impaired Litoditis marina development and lifespan, compared with Escherichia coli OP50 feeding; however, the underlying mechanisms remain unclear. Here, multi-omics approaches, including the transcriptome of both L. marina and bacteria, as well as the comparative bacterial metabolome, were utilized to investigate how bacterial food affects animal fitness and physiology. We found that genes related to iron ion binding and oxidoreductase activity pathways, such as agmo-1, cdo-1, haao-1, and tdo-2, were significantly upregulated in L. marina grown on S. algae, while extracellular structural components-related genes were significantly downregulated. Next, we observed that bacterial genes belonging to amino acid metabolism and ubiquinol-8 biosynthesis were repressed, while virulence genes were significantly elevated in S. algae. Furthermore, metabolomic analysis revealed that several toxic metabolites, such as puromycin, were enriched in S. algae, while many nucleotides were significantly enriched in OP50. Moreover, we found that the "two-component system" was enriched in S. algae, whereas "purine metabolism" and "one-carbon pool by folate" were significantly enriched in E. coli OP50. Collectively, our data provide new insights to decipher how diet modulates animal fitness and biology.

Separation of reproductive decline from lifespan extension during methionine restriction

Lifespan-extending interventions are generally thought to result in reduced fecundity. The generality of this principle and how it may extend to nutrition and metabolism is not understood. We considered dietary methionine restriction (MR), a lifespan-extending intervention linked to Mediterranean and plant-based diets. Using a chemically defined diet that we developed for Drosophila melanogaster, we surveyed the nutritional landscape in the background of MR and found that folic acid, a vitamin linked to one-carbon metabolism, notably was the lone nutrient that restored reproductive capacity while maintaining lifespan extension. In vivo isotope tracing, metabolomics and flux analysis identified the tricarboxylic cycle and redox coupling as major determinants of the MR-folic acid benefits, in part, as they related to sperm function. Together these findings suggest that dietary interventions optimized for longevity may be separable from adverse effects such as reproductive decline.

Distinct electrochemical and metabolic responses of anode respiring bacteria to sulfamethoxazole in microbial fuel cells coupled with constructed wetlands

The influence of sulfamethoxazole (SMX) on the electrochemical activity, bacterial community, and metabolic state of anode respiring microbes was investigated in constructed-wetland-coupled microbial fuel cells (CW-MFCs). Results suggested that SMX shortened the acclimatisation period and enhanced the maximal power density of the CW-MFC at 0.1 mg/L. Cyclic voltammetry (CV) results indicated that SMX may trigger an electrocatalytic process related to an extra redox-active compound. Exposure to SMX significantly altered the bacterial communities, leading to decreased abundances of Desulfurivibrio and Pseudomonas, while increasing the contents of Rhodobacter and Anaerovorax. Furthermore, metabolites related to amino acids and nucleotide metabolism were suppressed at 10 mg/L SMX, while the related metabolites increased at 0.1 mg/L SMX. The upregulated pathway of biofilm formation indicated that the bacteria tended to form biofilms under the influence of SMX. This study provides valuable insights into the complex interactions between SMX and electrochemically active bacteria.

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.

Dietary folate intake and serum klotho levels in adults aged 40-79 years: a cross-sectional study from the national health and nutrition examination survey 2007-2016

Objective

This study aims to explore the relationship between dietary folate intake and serum Klotho levels in adults from aged 40 to 79 years in the United States, seeking to elucidate the intricacies of their interaction.

Methods

Analyzing data from the National Health and Nutrition Examination Survey (NHANES) spanning 2007 to 2016. The survey research determined folate intake through a 24-h dietary recall and nutrient density modeling, and assessed Klotho levels using enzyme-linked immunosorbent assay (ELISA). The relationship between folate intake and Klotho levels was evaluated using weighted linear regression, and complemented by analysis via smoothed curve models for nuanced understanding.

Results

The study encompassed 10,278 participants, with an average age of 57.64 years, revealing a noteworthy positive correlation between dietary folate and serum Klotho levels. The regression coefficient stood at 0.11 (95% confidence interval, 0.05, 0.18) post-adjustment for various covariates. When dietary folate intake was categorized into quartiles, the second, third, and fourth quartiles exhibited statistically significant differences compared to the lowest quartile. This indicates that higher folate intake correlates with increased serum Klotho levels. These findings underscore the potential benefits of elevating folate intake to enhance serum Klotho levels. Stratified analysis indicated that this association was more pronounced among males aged 60 years or older and individuals with hypertension.

Conclusion

The findings suggest a significant correlation between increased dietary folate intake and elevated serum Klotho levels in adults aged 40-79 years. Hinting at the potential nutritional influences on the aging process and associated health conditions. This calls for further exploration into the mechanisms and broader implications of this association.

Loss of the histone chaperone UNC-85/ASF1 inhibits the epigenome-mediated longevity and modulates the activity of one-carbon metabolism

Histone H3/H4 chaperone anti-silencing function 1 (ASF1) is a conserved factor mediating nucleosomal assembly and disassembly, playing crucial roles in processes such as replication, transcription, and DNA repair. Nevertheless, its involvement in aging has remained unclear. Here, we utilized the model organism Caenorhabditis elegans to demonstrate that the loss of UNC-85, the homolog of ASF1, leads to a shortened lifespan in a multicellular organism. Furthermore, we show that UNC-85 is required for epigenome-mediated longevity, as knockdown of the histone H3 lysine K4 methyltransferase ash-2 does not extend the lifespan of unc-85 mutants. In this context, we found that the longevity-promoting ash-2 RNA interference enhances UNC-85 activity by increasing its nuclear localization. Finally, our data indicate that the loss of UNC-85 increases the activity of one-carbon metabolism, and that downregulation of the one-carbon metabolism component dao-3/MTHFD2 partially rescues the short lifespan of unc-85 mutants. Together, these findings reveal UNC-85/ASF1 as a modulator of the central metabolic pathway and a factor regulating a pro-longevity response, thus shedding light on a mechanism of how nucleosomal maintenance associates with aging.

Interactions of monolayer molybdenum disulfide sheets with metalloid antimony in aquatic environment: Adsorption, transformation, and joint toxicity

The tremendous application potentiality of transitional metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS2) nanosheets, will unavoidably lead to increasing release into the environment, which could influence the fate and toxicity of co-existed contaminants. The present study discovered that 59.8 % of trivalent antimony [Sb(III)] was transformed by MoS2 to pentavalent Sb [Sb(V)] in aqueous solutions under light illumination, which was due to hole oxidation on the nanosheet surfaces. A synergistic toxicity between MoS2 and Sb(III, V) to algae (Chlorella vulgaris) was observed, as demonstrated by the lower median-effect concentrations of MoS2 + Sb(III)/Sb(V) (13.1 and 20.9 mg/L, respectively) than Sb(III)/Sb(V) (38.8 and 92.5 mg/L, respectively) alone. Particularly, MoS2 at noncytotoxic doses notably increased the bioaccumulation of Sb(III, V) in algae, causing aggravated oxidative damage, photosynthetic inhibition, and structural alterations. Metabolomics indicated that oxidative stress and membrane permeabilization were primarily associated with down-regulated amino acids involved in glutathione biosynthesis and unsaturated fatty acids. MoS2 co-exposure remarkably decreased the levels of thiol antidotes (glutathione and phytochelatins) and aggravated the inhibition on energy metabolism and ATP synthesis, compromising the Sb(III, V) detoxification and efflux. Additionally, extracellular P was captured by the nanosheets, also contributing to the uptake of Sb(V). Our findings emphasized the nonignorability of TMDs even at environmental levels in affecting the ecological hazard of metalloids, providing insight into comprehensive safety assessment of TMDs.

The Role of One-Carbon Metabolism and Methyl Donors in Medically Assisted Reproduction: A Narrative Review of the Literature

One-carbon (1-C) metabolic deficiency impairs homeostasis, driving disease development, including infertility. It is of importance to summarize the current evidence regarding the clinical utility of 1-C metabolism-related biomolecules and methyl donors, namely, folate, betaine, choline, vitamin B12, homocysteine (Hcy), and zinc, as potential biomarkers, dietary supplements, and culture media supplements in the context of medically assisted reproduction (MAR). A narrative review of the literature was conducted in the PubMed/Medline database. Diet, ageing, and the endocrine milieu of individuals affect both 1-C metabolism and fertility status. In vitro fertilization (IVF) techniques, and culture conditions in particular, have a direct impact on 1-C metabolic activity in gametes and embryos. Critical analysis indicated that zinc supplementation in cryopreservation media may be a promising approach to reducing oxidative damage, while female serum homocysteine levels may be employed as a possible biomarker for predicting IVF outcomes. Nonetheless, the level of evidence is low, and future studies are needed to verify these data. One-carbon metabolism-related processes, including redox defense and epigenetic regulation, may be compromised in IVF-derived embryos. The study of 1-C metabolism may lead the way towards improving MAR efficiency and safety and ensuring the lifelong health of MAR infants.

Role of folate receptor α in the partial rejuvenation of dentate gyrus cells: Improvement of cognitive function in 21-month-old aged mice

Neuronal aging may be, in part, related to a change in DNA methylation. Thus, methyl donors, like folate and methionine, may play a role in cognitive changes associated to neuronal aging. To test the role of these metabolites, we performed stereotaxic microinjection of these molecules into the dentate gyrus (DG) of aged mice (an average age of 21 month). Folate, but not S-Adenosyl-Methionine (SAM), enhances cognition in aged mice. In the presence of folate, we observed partial rejuvenation of DG cells, characterized by the expression of juvenile genes or reorganization of extracellular matrix. Here, we have also tried to identify the mechanism independent of DNA methylation, that involve folate effects on cognition. Our analyses indicated that folate binds to folate receptor α (FRα) and, upon folate binding, FRα is transported to cell nucleus, where it is acting as transcription factor for expressing genes like SOX2 or GluN2B. In this work, we report that a FRα binding peptide also replicates the folate effect on cognition, in aged mice. Our data suggest that such effect is not sex-dependent. Thus, we propose the use of this peptide to improve cognition since it lacks of folate-mediated side effects. The use of synthetic FRα binding peptides emerge as a future strategy for the study of brain rejuvenation.

Epigenetic Genome Modifications during Pregnancy: The Impact of Essential Nutritional Supplements on DNA Methylation

Pregnancy is an extremely stressful period in a pregnant woman's life. Currently, women's awareness of the proper course of pregnancy and its possible complications is constantly growing. Therefore, a significant percentage of women increasingly reach for various dietary supplements during gestation. Some of the most popular substances included in multi-ingredient supplements are folic acid and choline. Those substances are associated with positive effects on fetal intrauterine development and fewer possible pregnancy-associated complications. Recently, more and more attention has been paid to the impacts of specific environmental factors, such as diet, stress, physical activity, etc., on epigenetic modifications, understood as changes occurring in gene expression without the direct alteration of DNA sequences. Substances such as folic acid and choline may participate in epigenetic modifications by acting via a one-carbon cycle, leading to the methyl-group donor formation. Those nutrients may indirectly impact genome phenotype by influencing the process of DNA methylation. This review article presents the current state of knowledge on the use of folic acid and choline supplementation during pregnancy, taking into account their impacts on the maternal-fetal unit and possible pregnancy outcomes, and determining possible mechanisms of action, with particular emphasis on their possible impacts on epigenetic modifications.

Package delivered: folate receptor-mediated transporters in cancer therapy and diagnosis

Neoplasias pose a significant threat to aging society, underscoring the urgent need to overcome the limitations of traditional chemotherapy through pioneering strategies. Targeted drug delivery is an evolving frontier in cancer therapy, aiming to enhance treatment efficacy while mitigating undesirable side effects. One promising avenue utilizes cell membrane receptors like the folate receptor to guide drug transporters precisely to malignant cells. Based on the cellular folate receptor as a cancer cell hallmark, targeted nanocarriers and small molecule-drug conjugates have been developed that comprise different (bio) chemistries and/or mechanical properties with individual advantages and challenges. Such modern folic acid-conjugated stimuli-responsive drug transporters provide systemic drug delivery and controlled release, enabling reduced dosages, circumvention of drug resistance, and diminished adverse effects. Since the drug transporters' structure-based de novo design is increasingly relevant for precision cancer remediation and diagnosis, this review seeks to collect and debate the recent approaches to deliver therapeutics or diagnostics based on folic acid conjugated Trojan Horses and to facilitate the understanding of the relevant chemistry and biochemical pathways. Focusing exemplarily on brain and breast cancer, recent advances spanning 2017 to 2023 in conjugated nanocarriers and small molecule drug conjugates were considered, evaluating the chemical and biological aspects in order to improve accessibility to the field and to bridge chemical and biomedical points of view ultimately guiding future research in FR-targeted cancer therapy and diagnosis.

Late-life dietary folate restriction reduces biosynthetic processes without compromising healthspan in mice

Folate is a vitamin required for cell growth and is present in fortified foods in the form of folic acid to prevent congenital abnormalities. The impact of low folate status on life-long health is poorly understood. We found that limiting folate levels with the folate antagonist methotrexate increased the lifespan of yeast and worms. We then restricted folate intake in aged mice and measured various health metrics, metabolites, and gene expression signatures. Limiting folate intake decreased anabolic biosynthetic processes in mice and enhanced metabolic plasticity. Despite reduced serum folate levels in mice with limited folic acid intake, these animals maintained their weight and adiposity late in life, and we did not observe adverse health outcomes. These results argue that the effectiveness of folate dietary interventions may vary depending on an individual's age and sex. A higher folate intake is advantageous during the early stages of life to support cell divisions needed for proper development. However, a lower folate intake later in life may result in healthier aging.

Folate receptor overexpression induces toxicity in a diet-dependent manner in C. elegans

Folate receptor (FR) alpha (FOLR1) and beta (FOLR2) are membrane-anchored folate transporters that are expressed at low levels in normal tissues, while their expression is strongly increased in several cancers. Intriguingly, although the function of these receptors in, for example, development and cancer has been studied intensively, their role in aging is still unknown. To address this, we utilized Caenorhabditis elegans, in which FOLR-1 is the sole ortholog of folate receptors. We found that the loss of FOLR-1 does not affect reproduction, physical condition, proteostasis or lifespan, indicating that it is not required for folate transport to maintain health. Interestingly, we found that FOLR-1 is detectably expressed only in uterine-vulval cells, and that the histone-binding protein LIN-53 inhibits its expression in other tissues. Furthermore, whereas knockdown of lin-53 is known to shorten lifespan, we found that the loss of FOLR-1 partially rescues this phenotype, suggesting that elevated folr-1 expression is detrimental for health. Indeed, our data demonstrate that overexpression of folr-1 is toxic, and that this phenotype is dependent on diet. Altogether, this work could serve as a basis for further studies to elucidate the organismal effects of abnormal FR expression in diseases such as cancer.

Uncovering the Hidden Dangers and Molecular Mechanisms of Excess Folate: A Narrative Review

This review delves into the intricate relationship between excess folate (vitamin B9) intake, especially its synthetic form, namely, folic acid, and its implications on health and disease. While folate plays a pivotal role in the one-carbon cycle, which is essential for DNA synthesis, repair, and methylation, concerns arise about its excessive intake. The literature underscores potential deleterious effects, such as an increased risk of carcinogenesis; disruption in DNA methylation; and impacts on embryogenesis, pregnancy outcomes, neurodevelopment, and disease risk. Notably, these consequences stretch beyond the immediate effects, potentially influencing future generations through epigenetic reprogramming. The molecular mechanisms underlying these effects were examined, including altered one-carbon metabolism, the accumulation of unmetabolized folic acid, vitamin-B12-dependent mechanisms, altered methylation patterns, and interactions with critical receptors and signaling pathways. Furthermore, differences in the effects and mechanisms mediated by folic acid compared with natural folate are highlighted. Given the widespread folic acid supplementation, it is imperative to further research its optimal intake levels and the molecular pathways impacted by its excessive intake, ensuring the health and well-being of the global population.

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.

A novel TNFRSF1A mutation associated with TNF-receptor-associated periodic syndrome and its metabolic signature

OBJECTIVE

We describe a family with a novel mutation in the TNF Receptor Superfamily Member 1A (TNFRSF1A) gene causing TNF receptor-associated periodic syndrome (TRAPS) with renal AA amyloidosis.

METHODS

Case series of affected family members. We further investigated the plasma metabolome of these patients in comparison with healthy controls using mass spectrometry.

RESULTS

In all symptomatic family members, we detected the previously undescribed variant c.332A>G (p.Q111R) in the TNFRSF1A gene. Canakinumab proved an effective treatment option leading to remission in all treated patients. One patient with suspected renal amyloidosis showed near normalization of proteinuria under treatment. Analysis of the metabolome revealed 31 metabolic compounds to be upregulated and 35 compounds to be downregulated compared with healthy controls. The most dysregulated metabolites belonged to pathways identified as arginine biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis, and cysteine and methionine metabolism. Interestingly, the metabolic changes observed in all three TRAPS patients seemed independent of treatment with canakinumab and subsequent remission.

CONCLUSION

We present a novel mutation in the TNFRSF1A gene associated with amyloidosis. Canakinumab is an effective treatment for individuals with this new likely pathogenic variant. Alterations in the metabolome were most prominent in the pathways related to arginine biosynthesis, tryptophan metabolism, and metabolism of cysteine and methionine, and seemed to be unaffected by treatment with canakinumab. Further investigation is needed to determine the role of these metabolomic changes in the pathophysiology of TRAPS.

Expanded bioinformatic analysis of Oximouse dataset reveals key putative processes involved in brain aging and cognitive decline

The theory that aging is driven by the damage produced by reactive oxygen species (ROS) derived from oxidative metabolism dominated geroscience studies during the second half of the 20th century. However, increasing evidence that ROS also plays a key role in the physiological regulation of numerous processes through the reversible oxidation of cysteine residues in proteins, has challenged this notion. Currently, the scope of redox signaling has reached proteomic dimensions through mass spectrometry techniques. Here, we perform a comprehensive bioinformatics analysis of cysteine oxidation changes during mouse brain aging, using the quantitative data provided in the Oximouse dataset. Interestingly, our unbiased analysis identified hundreds of putative cysteine redox switches covering several pathways previously associated with aging. These include the ubiquitin-proteasome pathway and one-carbon metabolism (folate cycle, methionine cycle, transsulfuration and polyamine pathways). Surprisingly, cysteine oxidation changes are enriched in synaptic proteins in a highly asymmetric distribution: while postsynaptic proteins tend to increase cysteine oxidation with age, the opposite occurs for presynaptic proteins. Additionally, cysteine oxidation changes during aging are associated with proteins involved in the regulation of the mitochondrial transition pore opening and synaptic calcium homeostasis. Our analysis reinforces the concept that brain aging is associated with selective changes in the oxidation state of key proteins, rather than an overall trend toward increased oxidation. Also, we provide a prioritized list of specific cysteine residues with putative impact in aging processes for future experimental validation.

Combinatorial interventions in aging

Insight on the underlying mechanisms of aging will advance our ability to extend healthspan, treat age-related pathology and improve quality of life. Multiple genetic and pharmacological manipulations extend longevity in different species, yet monotherapy may be relatively inefficient, and we have limited data on the effect of combined interventions. Here we summarize interactions between age-related pathways and discuss strategies to simultaneously retard these in different organisms. In some cases, combined manipulations additively increase their impact on common hallmarks of aging and lifespan, suggesting they quantitatively participate within the same pathway. In other cases, interactions affect different hallmarks, suggesting their joint manipulation may independently maximize their effects on lifespan and healthy aging. While most interaction studies have been conducted with invertebrates and show varying levels of translatability, the conservation of pro-longevity pathways offers an opportunity to identify 'druggable' targets relevant to multiple human age-associated pathologies.

Cdk12 maintains the integrity of adult axons by suppressing actin remodeling

The role of cyclin-dependent kinases (CDKs) that are ubiquitously expressed in the adult nervous system remains unclear. Cdk12 is enriched in terminally differentiated neurons where its conical role in the cell cycle progression is redundant. We find that in adult neurons Cdk12 acts a negative regulator of actin formation, mitochondrial dynamics and neuronal physiology. Cdk12 maintains the size of the axon at sites proximal to the cell body through the transcription of homeostatic enzymes in the 1-carbon by folate pathway which utilize the amino acid homocysteine. Loss of Cdk12 leads to elevated homocysteine and in turn leads to uncontrolled F-actin formation and axonal swelling. Actin remodeling further induces Drp1-dependent fission of mitochondria and the breakdown of axon-soma filtration barrier allowing soma restricted cargos to enter the axon. We demonstrate that Cdk12 is also an essential gene for long-term neuronal survival and loss of this gene causes age-dependent neurodegeneration. Hyperhomocysteinemia, actin changes, and mitochondrial fragmentation are associated with several neurodegenerative conditions such as Alzheimer's disease and we provide a candidate molecular pathway to link together such pathological events.

Modulation of DNA methylation by one-carbon metabolism: a milestone for healthy aging

Healthy aging can be defined as an extended lifespan and health span. Nutrition has been regarded as an important factor in healthy aging, because nutrients, bioactive food components, and diets have demonstrated beneficial effects on aging hallmarks such as oxidative stress, mitochondrial function, apoptosis and autophagy, genomic stability, and immune function. Nutrition also plays a role in epigenetic regulation of gene expression, and DNA methylation is the most extensively investigated epigenetic phenomenon in aging. Interestingly, age-associated DNA methylation can be modulated by one-carbon metabolism or inhibition of DNA methyltransferases. One-carbon metabolism ultimately controls the balance between the universal methyl donor S-adenosylmethionine and the methyltransferase inhibitor S-adenosylhomocysteine. Water-soluble B-vitamins such as folate, vitamin B6, and vitamin B12 serve as coenzymes for multiple steps in one-carbon metabolism, whereas methionine, choline, betaine, and serine act as methyl donors. Thus, these one-carbon nutrients can modify age-associated DNA methylation and subsequently alter the age-associated physiologic and pathologic processes. We cannot elude aging per se but we may at least change age-associated DNA methylation, which could mitigate age-associated diseases and disorders.

Mitochondrial aconitase suppresses immunity by modulating oxaloacetate and the mitochondrial unfolded protein response

Accumulating evidence indicates that mitochondria play crucial roles in immunity. However, the role of the mitochondrial Krebs cycle in immunity remains largely unknown, in particular at the organism level. Here we show that mitochondrial aconitase, ACO-2, a Krebs cycle enzyme that catalyzes the conversion of citrate to isocitrate, inhibits immunity against pathogenic bacteria in C. elegans. We find that the genetic inhibition of aco-2 decreases the level of oxaloacetate. This increases the mitochondrial unfolded protein response, subsequently upregulating the transcription factor ATFS-1, which contributes to enhanced immunity against pathogenic bacteria. We show that the genetic inhibition of mammalian ACO2 increases immunity against pathogenic bacteria by modulating the mitochondrial unfolded protein response and oxaloacetate levels in cultured cells. Because mitochondrial aconitase is highly conserved across phyla, a therapeutic strategy targeting ACO2 may eventually help properly control immunity in humans.

One-carbon metabolic enzymes are regulated during cell division and make distinct contributions to the metabolome and cell cycle progression in Saccharomyces cerevisiae

Enzymes of one-carbon (1C) metabolism play pivotal roles in proliferating cells. They are involved in the metabolism of amino acids, nucleotides, and lipids and the supply of all cellular methylations. However, there is limited information about how these enzymes are regulated during cell division and how cell cycle kinetics are affected in several loss-of-function mutants of 1C metabolism. Here, we report that the levels of the S. cerevisiae enzymes Ade17p and Cho2p, involved in the de novo synthesis of purines and phosphatidylcholine (PC), respectively, are cell cycle-regulated. Cells lacking Ade17p, Cho2p, or Shm2p (an enzyme that supplies 1C units from serine) have distinct alterations in size homeostasis and cell cycle kinetics. Loss of Ade17p leads to a specific delay at START, when cells commit to a new round of cell division, while loss of Shm2p has broader effects, reducing growth rate. Furthermore, the inability to synthesize PC de novo in cho2Δ cells delays START and reduces the coherence of nuclear elongation late in the cell cycle. Loss of Cho2p also leads to profound metabolite changes. Besides the expected changes in the lipidome, cho2Δ cells have reduced levels of amino acids, resembling cells shifted to poorer media. These results reveal the different ways that 1C metabolism allocates resources to affect cell proliferation at multiple cell cycle transitions.

Metabolic reprogramming by Acly inhibition using SB-204990 alters glucoregulation and modulates molecular mechanisms associated with aging

ATP-citrate lyase is a central integrator of cellular metabolism in the interface of protein, carbohydrate, and lipid metabolism. The physiological consequences as well as the molecular mechanisms orchestrating the response to long-term pharmacologically induced Acly inhibition are unknown. We report here that the Acly inhibitor SB-204990 improves metabolic health and physical strength in wild-type mice when fed with a high-fat diet, while in mice fed with healthy diet results in metabolic imbalance and moderated insulin resistance. By applying a multiomic approach using untargeted metabolomics, transcriptomics, and proteomics, we determined that, in vivo, SB-204990 plays a role in the regulation of molecular mechanisms associated with aging, such as energy metabolism, mitochondrial function, mTOR signaling, and folate cycle, while global alterations on histone acetylation are absent. Our findings indicate a mechanism for regulating molecular pathways of aging that prevents the development of metabolic abnormalities associated with unhealthy dieting. This strategy might be explored for devising therapeutic approaches to prevent metabolic diseases.

The Role of Microbiota-Derived Vitamins in Immune Homeostasis and Enhancing Cancer Immunotherapy

Not all cancer patients who receive immunotherapy respond positively and emerging evidence suggests that the gut microbiota may be linked to treatment efficacy. Though mechanisms of microbial contributions to the immune response have been postulated, one likely function is the supply of basic co-factors to the host including selected vitamins. Bacteria, fungi, and plants can produce their own vitamins, whereas humans primarily obtain vitamins from exogenous sources, yet despite the significance of microbial-derived vitamins as crucial immune system modulators, the microbiota is an overlooked source of these nutrients in humans. Microbial-derived vitamins are often shared by gut bacteria, stabilizing bioenergetic pathways amongst microbial communities. Compositional changes in gut microbiota can affect metabolic pathways that alter immune function. Similarly, the immune system plays a pivotal role in maintaining the gut microbiota, which parenthetically affects vitamin biosynthesis. Here we elucidate the immune-interactive mechanisms underlying the effects of these microbially derived vitamins and how they can potentially enhance the activity of immunotherapies in cancer.

S-adenosylmethionine synthases specify distinct H3K4me3 populations and gene expression patterns during heat stress

Methylation is a widely occurring modification that requires the methyl donor S-adenosylmethionine (SAM) and acts in regulation of gene expression and other processes. SAM is synthesized from methionine, which is imported or generated through the 1-carbon cycle (1 CC). Alterations in 1 CC function have clear effects on lifespan and stress responses, but the wide distribution of this modification has made identification of specific mechanistic links difficult. Exploiting a dynamic stress-induced transcription model, we find that two SAM synthases in Caenorhabditis elegans, SAMS-1 and SAMS-4, contribute differently to modification of H3K4me3, gene expression and survival. We find that sams-4 enhances H3K4me3 in heat shocked animals lacking sams-1, however, sams-1 cannot compensate for sams-4, which is required to survive heat stress. This suggests that the regulatory functions of SAM depend on its enzymatic source and that provisioning of SAM may be an important regulatory step linking 1 CC function to phenotypes in aging and stress.

Anti-retroviral treatment with zidovudine alters pyrimidine metabolism, reduces translation, and extends healthy longevity via ATF-4

The human population is aging, and the need for interventions to slow progression of age-related diseases (geroprotective interventions) is growing. Repurposing compounds already used clinically, usually at modified doses, allows rapid implementation of geroprotective pharmaceuticals. Here we find the anti-retroviral nucleoside reverse transcriptase inhibitor (NRTI) zidovudine robustly extends lifespan and health span in C. elegans, independent of electron transport chain impairment or ROS accumulation. Rather, zidovudine treatment modifies pyrimidine metabolism and transcripts related to proteostasis. Testing regulators of mitochondrial stress and proteostasis shows that lifespan extension is dependent on activating transcription factor 4 (ATF-4). ATF-4 regulates longevity induced by mitochondrial stress, specifically communication between mitochondrial and cytosolic translation. Translation is reduced in zidovudine-treated worms, also dependent on ATF-4. Finally, we show ATF-4-dependent lifespan extension induced by didanosine, another NRTI. Altogether, our work elucidates the geroprotective effects of NRTIs such as zidovudine in vivo, via reduction of translation and ATF-4.

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.

Folate inhibits lipid deposition via the autophagy pathway in chicken hepatocytes

Excessive fat deposition affects the efficiency and quality of broiler meat production. To understand the molecular mechanism underlying abdominal fat content of broiler lines under divergent selection, we have attempted multiple genetics and genomics methods previously. However, the molecular mechanism of hepatic fat deposition remains largely unknown. On broiler lines divergently selected for abdominal fat content, we performed integrated mRNA and lncRNA sequencing on liver tissues. Key genes and signaling pathways related to the biosynthesis, elongation and metabolism of fatty acids, metabolic pathways, and folate biosynthesis were revealed. Then, primary hepatocytes (sex determined) were isolated and cultured, and treatment concentrations of folate and palmitic acid were optimized. Expression profiling on primary hepatocytes treated by folate and/or palmitic acid revealed that folic acid inhibited lipid deposition in a sex-dependent way, through regulating transcriptional and protein levels of genes related to DNA methylation, lipid metabolism (mTOR/SREBP-1c/PI3K), and autophagy (LAMP2/ATG5) pathways. Taken together, folate could interfere with hepatic lipid deposition possibly through the involvement of the autophagy pathway in broilers.

Circulating cell-free DNA in health and disease - the relationship to health behaviours, ageing phenotypes and metabolomics

Circulating cell-free DNA (cf-DNA) has emerged as a promising biomarker of ageing, tissue damage and cellular stress. However, less is known about health behaviours, ageing phenotypes and metabolic processes that lead to elevated cf-DNA levels. We sought to analyse the relationship of circulating cf-DNA level to age, sex, smoking, physical activity, vegetable consumption, ageing phenotypes (physical functioning, the number of diseases, frailty) and an extensive panel of biomarkers including blood and urine metabolites and inflammatory markers in three human cohorts (N = 5385; 17-82 years). The relationships were assessed using correlation statistics, and linear and penalised regressions (the Lasso), also stratified by sex.cf-DNA levels were significantly higher in men than in women, and especially in middle-aged men and women who smoke, and in older more frail individuals. Correlation statistics of biomarker data showed that cf-DNA level was higher with elevated inflammation (C-reactive protein, interleukin-6), and higher levels of homocysteine, and proportion of red blood cells and lower levels of ascorbic acid. Inflammation (C-reactive protein, glycoprotein acetylation), amino acids (isoleucine, leucine, tyrosine), and ketogenesis (3-hydroxybutyrate) were included in the cf-DNA level-related biomarker profiles in at least two of the cohorts.In conclusion, circulating cf-DNA level is different by sex, and related to health behaviour, health decline and metabolic processes common in health and disease. These results can inform future studies where epidemiological and biological pathways of cf-DNA are to be analysed in details, and for studies evaluating cf-DNA as a potential clinical marker.

S-adenosyl-L-homocysteine extends lifespan through methionine restriction effects

Methionine restriction (MetR) can extend lifespan and delay the onset of aging-associated pathologies in most model organisms. Previously, we showed that supplementation with the metabolite S-adenosyl-L-homocysteine (SAH) extends lifespan and activates the energy sensor AMP-activated protein kinase (AMPK) in the budding yeast Saccharomyces cerevisiae. However, the mechanism involved and whether SAH can extend metazoan lifespan have remained unknown. Here, we show that SAH supplementation reduces Met levels and recapitulates many physiological and molecular effects of MetR. In yeast, SAH supplementation leads to inhibition of the target of rapamycin complex 1 (TORC1) and activation of autophagy. Furthermore, in Caenorhabditis elegans SAH treatment extends lifespan by activating AMPK and providing benefits of MetR. Therefore, we propose that SAH can be used as an intervention to lower intracellular Met and confer benefits of MetR.

Meeting Report: Aging Research and Drug Discovery

Aging is the single largest risk factor for most chronic diseases, and thus possesses large socioeconomic interest to continuously aging societies. Consequently, the field of aging research is expanding alongside a growing focus from the industry and investors in aging research. This year’s 8th Annual Aging Research and Drug Discovery (ARDD) meeting was organized as a hybrid meeting from August 30th to September 3rd 2021 with more than 130 attendees participating on-site at the Ceremonial Hall at University of Copenhagen, Denmark, and 1800 engaging online. The conference comprised of presentations from 75 speakers focusing on new research in topics including mechanisms of aging and how these can be modulated as well as the use of AI and new standards of practices within aging research. This year, a longevity workshop was included to build stronger connections with the clinical community.

One-Carbon Metabolism: Pulling the Strings behind Aging and Neurodegeneration

One-carbon metabolism (OCM) is a network of biochemical reactions delivering one-carbon units to various biosynthetic pathways. The folate cycle and methionine cycle are the two key modules of this network that regulate purine and thymidine synthesis, amino acid homeostasis, and epigenetic mechanisms. Intersection with the transsulfuration pathway supports glutathione production and regulation of the cellular redox state. Dietary intake of micronutrients, such as folates and amino acids, directly contributes to OCM, thereby adapting the cellular metabolic state to environmental inputs. The contribution of OCM to cellular proliferation during development and in adult proliferative tissues is well established. Nevertheless, accumulating evidence reveals the pivotal role of OCM in cellular homeostasis of non-proliferative tissues and in coordination of signaling cascades that regulate energy homeostasis and longevity. In this review, we summarize the current knowledge on OCM and related pathways and discuss how this metabolic network may impact longevity and neurodegeneration across species.

Methotrexate Disposition, Anti-Folate Activity, and Metabolomic Profiling to Identify Molecular Markers of Disease Activity and Drug Response in the Collagen-Induced Arthritis Mouse Model

Methotrexate (MTX) is widely used in the treatment of autoimmune arthritis but is limited by its unpredictable and variable response profile. Currently, no biomarkers exist to predict or monitor early therapeutic responses to MTX. Using a collagen-induced arthritis (CIA) mouse model, this study aimed to identify biochemical pathways and biomarkers associated with MTX efficacy in autoimmune arthritis. Following arthritis disease induction, DBA/1J mice were treated with subcutaneous MTX (20 mg/kg/week) and disease activity was assessed based on disease activity scores (DAS) and paw volume (PV) measurements. Red blood cell (RBC) and plasma samples were collected at the end of the study and were assessed for folate and MTX content. Plasma samples were analyzed by semitargeted global metabolomic profiling and analyzed by univariate and multivariate analysis. Treatment with MTX was associated with significant reductions in disease activity based on both DAS (p = 0.0006) and PV (p = 0.0006). MTX therapy resulted in significant reductions in 5-methyltetrahydrofolate (5mTHF) levels in plasma (p = 0.02) and RBCs (p = 0.001). Reductions in both RBC and plasma 5mTHF were associated with lower DAS (p = 0.0007, p = 0.01, respectively) and PV (p = 0.001, p = 0.005, respectively). Increases in RBC MTX were associated with lower DAS (p = 0.003) but not PV (p = 0.23). Metabolomic analysis identified N-methylisoleucine (NMI) and quinolone as metabolites significantly altered in disease mice, which were corrected towards healthy control levels in mice treated with MTX. Reductions in plasma NMI were associated with lower DAS (p = 0.0002) and PV (p = 9.5 × 10^-6). Increases in plasma quinolone were associated with lower DAS (p = 0.02) and PV (p = 0.01). Receiver-operating characteristic curve analysis identified plasma NMI (AUC = 1.00, p = 2.4 × 10^-8), RBC 5mTHF (AUC = 0.99, p = 2.4 × 10^-5), and plasma quinolone (AUC = 0.89, p = 0.01) as top discriminating metabolites of MTX treatment. Our data support a relationship between MTX efficacy and its effect on circulating folates and identified 5mTHF, NMI, and quinolone as potential therapeutic biomarkers of disease activity and MTX response in the CIA mouse model of autoimmune arthritis.

MoS2 Nanosheets-Cyanobacteria Interaction: Reprogrammed Carbon and Nitrogen Metabolism

Fully understanding the environmental implications of engineered nanomaterials is crucial for their safe and sustainable use. Cyanobacteria, as the pioneers of the planet earth, play important roles in global carbon and nitrogen cycling. Here, we evaluated the biological effects of molybdenum disulfide (MoS₂) nanosheets on a N₂-fixation cyanobacteria (Nostoc sphaeroides) by monitoring growth and metabolome changes. MoS₂ nanosheets did not exert overt toxicity to Nostoc at the tested doses (0.1 and 1 mg/L). On the contrary, the intrinsic enzyme-like activities and semiconducting properties of MoS₂ nanosheets promoted the metabolic processes of Nostoc, including enhancing CO₂-fixation-related Calvin cycle metabolic pathway. Meanwhile, MoS₂ boosted the production of a range of biochemicals, including sugars, fatty acids, amino acids, and other valuable end products. The altered carbon metabolism subsequently drove proportional changes in nitrogen metabolism in Nostoc. These intracellular metabolic changes could potentially alter global C and N cycles. The findings of this study shed light on the nature and underlying mechanisms of bio-nanoparticle interactions, and offer the prospect of utilization bio-nanomaterials for efficient CO₂ sequestration and sustainable biochemical production.