daf-2, an insulin receptor-like gene that regulates longevity and diapause in Caenorhabditis elegans

CDK-4 regulates nucleolar size and metabolism at the cost of late-life fitness in C. elegans

Studies on aging have centered on two molecular pathways: CDK4/6 and insulin/mTORC1. These pathways are thought to influence aging through distinct mechanisms: mTORC1 by reprogramming systemic metabolism, and CDK4 through p16-mediated senescence and inflammatory signaling (SASP). Here, we investigate the connection between aging and CDK4 in Caenorhabditis elegans, an organism lacking both p16 and SASP. Using a conditional degradation system, we demonstrate that CDK-4 inhibition in C. elegans phenocopies its aging-related functions observed in mammals. Worms with depleted CDK-4 exhibited accelerated aging phenotypes, including reduced lifespan, decreased motility, increased yolk accumulation, and earlier onset of senescence. At the physiological level, CDK4-inhibited worms show substantial metabolic shifts; including enhanced protein synthesis, elevated ATP production, and increased fat accumulation. These metabo-aging phenotypes occur independently of mTORC1, instead operating through the canonical CDK-4 effectors LIN-35 (Rb) and EFL-1 (E2F).

Chromatin and epigenetics in aging biology

This book chapter will focus on modifications to chromatin itself, how chromatin modifications are regulated, and how these modifications are deciphered by the cell to impact aging. In this chapter, we will review how chromatin modifications change with age, examine how chromatin-modifying enzymes have been shown to regulate aging and healthspan, discuss how some of these epigenetic changes are triggered and how they can regulate the lifespan of the individual and its naïve descendants, and speculate on future directions for the field.

Crocin extends lifespan by mitigating oxidative stress and regulating lipid metabolism through the DAF-16/FOXO pathway

Aging represents a significant global challenge characterized by persistent oxidative stress and dysregulated lipid metabolism. Crocin, the primary bioactive constituent of saffron (Crocus sativus L.), is widely utilized as a natural food colorant and exhibits potent anti-inflammatory and antioxidant properties. Previous studies have demonstrated crocin's antioxidative, neuroprotective and memory-enhancing effects in aged rats; however, its direct impact on aging and the underlying mechanisms remain unexplored. In this study, we demonstrated that crocin treatment extended lifespan, enhanced survival under heat and juglone-induced oxidative stress, and reduced lipofuscin accumulation in the model organism C. elegans. Mechanistically, crocin activated DAF-16, the C. elegans homolog of human FOXO, resulting in the upregulation of key antioxidant genes (gst-4, sod-3 and hsp-16.2). Notably, the lifespan-extension effect of crocin was abolished in a daf-16 mutant, and its antioxidant effects were significantly attenuated in daf-16 RNAi experiments conducted in N2, CL2166, CF1553 and TJ375 strains. Furthermore, crocin specifically reduced fat accumulation, and upregulated the expression of genes involved in lipid mobilization (lipl-3, lipl-4, atgl-1 and acs-2) and unsaturated fatty acid synthesis (fat-6 and elo-2) in aged nematodes. GC-MS analysis further demonstrated that crocin treatment elevated the levels of unsaturated fatty acids (C18:1n9, C20:4n-6, C20:4n-3 and C20:5n-3), an effect that was completely abolished under daf-16 knockdown conditions. Collectively, these findings suggest that crocin promotes longevity in C. elegans by mitigating oxidative stress and modulating lipid metabolism through the DAF-16/FOXO pathway. These results highlight the potential of crocin as a promising strategy for treating aging and age-related diseases.

Natural anti-aging innovations: Bakuchiol role in longevity and stress resilience through DAF-16 pathway activation

Drawing from the deep-rooted knowledge of traditional medicine, the Fabaceae family particularly Psoralea corylifolia has been esteemed for its natural remedies against aging. In this study Bakuchiol, a phenolic compound derived from P.corylifolia is explored for its potential to mitigate age-related deterioration through a close examination of its effects on Caenorhabditis elegans. Rather than seeing aging as mere decline, we investigate it as a dynamic process of molecular changes where Bakuchiol may play a pivotal role by influencing key genetic pathways to counter cellular damage and oxidative stress. Using a range of C. elegans strains including those with precise genetic modifications, this study probes Bakuchiol interaction with essential regulators of aging primarily the DAF-16 transcription factor, a counterpart to mammalian FOXO and the insulin/insulin-like growth factor (IIS) pathway. The findings show that Bakuchiol at an optimal concentration of 37.5 μM meaningfully extends lifespan and enhances resilience to stress independent of microbial influences. Notably, Bakuchiol promotes the nuclear translocation of DAF-16, up regulates stress-response genes and boosts the activity of superoxide dismutase (SOD-3) solidifying its role in modulating aging via conserved genetic mechanisms. This research highlights Bakuchiol potential as a powerful natural agent for aging intervention enriching the field of biogerontology and pointing toward the translational promise of plant derived compounds in developing advanced anti-aging therapies.

Insulin/insulin-like growth factor signaling pathway promotes higher fat storage in Drosophila females

In Drosophila , adult females store more fat than males. While the mechanisms that restrict body fat in males are becoming clearer, less is known about how females achieve higher fat storage. Here, we perform a detailed investigation of the mechanisms that promote higher fat storage in females. We show greater intake of dietary sugar supports higher fat storage due to female-biased remodeling of the fat body lipidome. Dietary sugar stimulates a female-specific increase in Drosophila insulin-like peptide 3 (Dilp3), which acts together with greater peripheral insulin sensitivity to augment insulin/insulin-like growth factor signaling pathway (IIS) activity in adult females. Indeed, Dilp3 overexpression prevented the female-biased decrease in body fat after removal of dietary sugar. Given that adult-specific IIS inhibition caused a female-biased decrease in body fat, our data reveal IIS as a key determinant of female fat storage.

Molecular, neural, and tissue circuits underlying physiological temperature responses in Caenorhabditis elegans

Temperature is a constant environmental factor on Earth, acting as a continuous stimulus that organisms must constantly perceive to survive. Organisms possess neural systems that receive various types of environmental information, including temperature, and mechanisms for adapting to their surroundings. This paper provides insights into the neural circuits and intertissue networks involved in physiological temperature responses, specifically the mechanisms of "cold tolerance" and "temperature acclimation," based on an analysis of the nematode Caenorhabditis elegans as an experimental system for neural and intertissue information processing.

Chrysophanol delays aging via insulin/IGF-1 signaling pathway

Aging is inevitable processes which play a significant role in the development of various diseases, including cardiovascular diseases, neurodegenerative disorders, and cancers. The extension of lifespan and the improvement of age-related diseases can potentially be achieved by targeting evolutionarily conserved pathways and mechanisms through pharmacological interventions. Chrysophanol (Chr), a naturally occurring anthraquinone compound primarily derived from rhubarb of the Polygonaceae family, exhibits a wide range of pharmacological activities, including anti-cancer, anti-inflammatory, and anti-bacterial effects. However, its role in regulating aging remains unclear. In this study, we discovered that Chr extends both lifespan and healthspan in Caenorhabditis elegans by activating the DAF-2/DAF-16 insulin signaling pathway. Furthermore, we observed that Chr promoted longevity in natural aging mice, doxorubicin-induced aging mice, and transgenic mice through the conserved Insulin/IGF-1 signaling pathway. Additionally, Chr also influenced senescence-associated secretory phenotypes (SASPs) and enhanced the expression of antioxidant genes, contributing to delayed aging. These findings highlight that Chr exerts anti-aging effects from C. elegans to mammals via the evolutionarily conserved Insulin/IGF-1 signaling pathway, positioning Chr as a promising candidate for the prevention and treatment of aging and age-related diseases.

Alleviating Effects of Ethanol Extract from Acremonium terricola Culture on Patulin Toxicity

Exposure to patulin (PAT) poses a significant health risk to animals, emphasizing the need for natural, safe substances to mitigate toxicity. Acremonium terricola culture (ATC), a fungal fermentation-derived feed additive, is known for its antioxidant properties, yet its potential to alleviate mycotoxin-induced toxicity remains largely uninvestigated. In this study, the ethanol extracts from the ATC (EEAT) were prepared with a total phenolic content of 67.9 mg GAE/g and a total flavonoid content of 32.7 mg RE/g. Ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UPLC-ESI-MS/MS) analysis was employed to investigate the bioactive components in EEAT. In PAT-exposed Caenorhabditis elegans models, EEAT treatment significantly enhanced locomotory capacity and elevated antioxidant enzyme activities by 63.1% (SOD) and 90.1% (GSH-ST), respectively. Molecular docking analysis revealed that key active compounds in EEAT, such as coumarin, succinic acid, and trigonelline, exhibited effective binding affinities to potential targets SIR-2.1 and DAF-2. Notably, coumarin and trigonelline were most effective in alleviating PAT toxicity, as evidenced by rescued locomotor rates and oxidative impairment in C. elegans. Our findings not only elucidate the molecular basis of EEAT-mediated PAT mitigation but also establish A. terricola culture as a sustainable antioxidant.

Conserved components of the macroautophagy machinery in Caenorhabditis elegans

Macroautophagy involves the sequestration of cytoplasmic contents in a double-membrane autophagosome and its subsequent delivery to lysosomes for degradation and recycling. In Caenorhabditis elegans, autophagy participates in diverse processes such as stress resistance, cell fate specification, tissue remodeling, aging, and adaptive immunity. Genetic screens in C. elegans have identified a set of metazoan-specific autophagy genes that form the basis for our molecular understanding of steps unique to the autophagy pathway in multicellular organisms. Suppressor screens have uncovered multiple mechanisms that modulate autophagy activity under physiological conditions. C. elegans also provides a model to investigate how autophagy activity is coordinately controlled at an organismal level. In this chapter, we will discuss the molecular machinery, regulation, and physiological functions of autophagy, and also methods utilized for monitoring autophagy during C. elegans development.

Dynamic changes in gene expression through aging in Drosophila melanogaster heads

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

Activated SKN-1 alters the aging trajectories of long-lived Caenorhabditis elegans mutants

In the presence of stressful environments, the SKN-1 cytoprotective transcription factor is activated to induce the expression of gene targets that can restore homeostasis. However, chronic activation of SKN-1 results in diminished health and a reduction of lifespan. Here, we demonstrate the necessity of modulating SKN-1 activity to maintain the longevity-promoting effects associated with genetic mutations that impair daf-2/insulin receptor signaling, the eat-2 model of dietary restriction, and glp-1-dependent loss of germ cell proliferation. A hallmark of animals with constitutive SKN-1 activation is the age-dependent loss of somatic lipids, and this phenotype is linked to a general reduction in survival in animals harboring the skn-1gf allele. Surprisingly, daf-2lf; skn-1gf double mutant animals do not redistribute somatic lipids, which suggests the insulin signaling pathway functions downstream of SKN-1 in the maintenance of lipid distribution. As expected, the eat-2lf allele, which independently activates SKN-1, continues to display somatic lipid depletion in older ages with and without the skn-1gf activating mutation. In contrast, the presence of the skn-1gf allele does not lead to somatic lipid redistribution in glp-1lf animals that lack a proliferating germline. Taken together, these studies support a genetic model where SKN-1 activity is an important regulator of lipid mobilization in response to nutrient availability that fuels the developing germline by engaging the daf-2/insulin receptor pathway.

Genetically encoded biosensor for fluorescence lifetime imaging of PTEN dynamics in the intact brain

The phosphatase and tensin homolog (PTEN) is a vital protein that maintains an inhibitory brake for cellular proliferation and growth. Accordingly, PTEN loss-of-function mutations are associated with a broad spectrum of human pathologies. Despite its importance, there is currently no method to directly monitor PTEN activity with cellular specificity within intact biological systems. Here we describe the development of a FRET-based biosensor using PTEN conformation as a proxy for the PTEN activity state, for two-photon fluorescence lifetime imaging microscopy. We identify a point mutation that allows the monitoring of PTEN activity with minimal interference to endogenous PTEN signaling. We demonstrate imaging of PTEN activity in cell lines, intact Caenorhabditis elegans and in the mouse brain. Finally, we develop a red-shifted sensor variant that allows us to identify cell-type-specific PTEN activity in excitatory and inhibitory cortical cells. In summary, our approach enables dynamic imaging of PTEN activity in vivo with unprecedented spatial and temporal resolution.

FRPR-1, a G protein-coupled receptor in the FMRFamide-related peptide receptor family, modulates larval development as a receptor candidate of the FMRFamide-like peptide FLP-1 in Caenorhabditis elegans

FMRFamide-like peptides (FLPs) and their receptors, FMRFamide-related peptide receptors (FRPRs) are widely conserved in free-living and parasitic nematodes. Herein, we identified FRPR-1 as an FLP-1 receptor candidate involved in larval development and diapause in the model nematode Caenorhabditis elegans. Our molecular genetic study, supported by in silico research, revealed the following: (1) frpr-1 loss-of-function completely suppresses the promotion of larval diapause caused by flp-1 overexpression; (2) AlphaFold2 analysis revealed the binding of FLP-1 to FRPR-1; (3) FRPR-1 as well as FLP-1 modulates the production and secretion of the predominant insulin-like peptide DAF-28, which is produced in ASI neurons; and (4) the suppression of larval diapause by frpr-1 loss-of-function is completely suppressed by a daf-28 defect. Thus, FRPR-1 regulates larval development and diapause by modulating DAF-28 production and secretion. This study may provide new insights into the development of novel nematicides targeting parasitic nematodes using FRPR-1 inhibitors.

Developmental and conditional regulation of DAF-2/INSR ubiquitination in Caenorhabditis elegans

Insulin/IGF signaling (IIS) regulates developmental and metabolic plasticity. Conditional regulation of insulin-like peptide expression and secretion promotes different phenotypes in different environments. However, IIS can also be regulated by other, less understood mechanisms. For example, stability of the only known insulin/IGF receptor in Caenorhabditis elegans, DAF-2/INSR, is regulated by CHIP-dependent ubiquitination. Disruption of chn-1/CHIP reduces longevity in C. elegans by increasing DAF-2/INSR abundance and IIS activity in adults. Likewise, mutation of a ubiquitination site causes daf-2(gk390525) to display gain-of-function phenotypes in adults. However, we show that this allele displays loss-of-function phenotypes in larvae and that its effect on IIS activity transitions from negative to positive during development. In contrast, the allele acts like a gain-of-function in larvae cultured at high temperature, inhibiting temperature-dependent dauer formation. Disruption of chn-1/CHIP causes an increase in IIS activity in starved L1 larvae, unlike daf-2(gk390525). CHN-1/CHIP ubiquitinates DAF-2/INSR at multiple sites. These results suggest that the sites that are functionally relevant to negative regulation of IIS vary in larvae and adults, at different temperatures, and in nutrient-dependent fashion, revealing additional layers of IIS regulation.

Environmental NaCl affects C. elegans development and aging

Sodium is an essential nutrient, but is toxic in excess. In humans, excessive dietary sodium can cause high blood pressure, which contributes to age-related diseases including stroke and heart disease. We used C. elegans to elucidate how sodium levels influence animal aging. Most experiments on this animal are conducted in standard culture conditions: Nematode Growth Medium (NGM) agar with a lawn of E. coli. Here, we report that the supplemental NaCl in standard NGM, 50 mM, accelerates aging and decreases lifespan. For comparison, we prepared NGM with reduced NaCl or excess NaCl. Considering reduced NaCl as a baseline, wild-type worms on standard NGM displayed normal development and fertility but reduced lifespan and health span, indicating toxicity in old animals. The long-lived mutants daf-2, age-1, and nuo-6, cultured on standard NGM, also displayed reduced lifespan. Thus, NaCl in standard NGM accelerates aging in multiple genetic backgrounds. Wild-type worms on excess NaCl displayed delayed development and reduced fertility, and reduced lifespan and health span, indicating toxicity in both young and old animals. These results suggest that young animals are relatively resistant to NaCl toxicity, but that aging causes progressive sensitivity, such that old animals display toxicity to both standard and excess NaCl. We investigated pathways that respond to NaCl. Young animals cultured with excess NaCl activated gpdh-1, a specific response to NaCl stress. Old animals cultured with excess NaCl activated gpdh-1 and hsp-6, a reporter for the mitochondrial unfolded protein response. Thus, excess NaCl activates multiple stress response pathways in older animals.

Mitochondrial Proteome Reveals Metabolic Tuning by Restricted Insulin Signaling to Promote Longevity in Caenorhabditis elegans

Aging is a time-dependent process of functional decline influenced by genetic and environmental factors. Age-related mitochondrial changes remain incompletely understood. Here, we found that compared to the wild type, the mitochondria of long-lived daf-2 C. elegans maintain youthful morphology and function. Through quantitative proteomic analysis on isolated mitochondria, we identified 257 differentially expressed candidates. Analysis of these changed mitochondrial proteins reveals a significant upregulation of five key mitochondrial metabolic pathways in daf-2 mutants, including branched-chain amino acids (BCAA), reactive oxygen species (ROS), propionate, β-alanine, and fatty acids (FA), all of which are related to daf-2-mediated longevity. In addition, mitochondrial ribosome protein abundance slightly decreased in daf-2 mutants. A mild reduction in mitochondrial elongation factor G (gfm-1) by RNAi extends the lifespan of wild type while decreasing lipid metabolic process and cytoplasmic fatty acid metabolism, suggesting that proper inhibition of mitochondrial translation activity might be important for lifespan extension. Overall, our findings indicate that mitochondrial metabolic modulation contributes to the longevity of daf-2 mutants and further highlights the crucial role of mitochondria in aging.

A comprehensive approach, based on the use of Caenorhabditis elegans, mouse, and human models, elucidates the impact of Lactiplantibacillus plantarum TWK10 on exercise performance and longevity

The functionality of probiotics is highly influenced by culture and processing conditions, making batch stability validation through human or mouse trials impractical. Here, we employed a comprehensive approach using Caenorhabditis elegans, mouse and human models to elucidate the beneficial effects of Lactiplantibacillus plantarum TWK10 (TWK10). In C. elegans, TWK10 administration significantly prolonged lifespan by 26.1 ± 11.9 % (p < 0.05), enhanced locomotion (p < 0.01) and muscle mass (p < 0.001), elevated glycogen storage (p < 0.05), and reduced lipid accumulation (p < 0.001), outperforming Lacticaseibacillus rhamnosus GG and L. plantarum type strain ATCC 14917T. We also confirmed the equivalence of laboratory-prepared and mass-produced TWK10 in ergogenic efficacy using C. elegans assay. In mice, oral administration of mass-produced TWK10 significantly enhanced exercise performance and glycogen storage in muscle and liver in a dose-dependent manner. In a clinical study involving healthy male adults, significant improvements in grip strength (1.1-fold, p < 0.01) and exhaustion time (1.27-fold, p < 0.01), and significant reductions in circulating lactate and ammonia levels were observed in the TWK10 group (1 × 1010 colony-forming unit/day) compared to the control group. Both humans and mice receiving mass-produced TWK10 showed improved body composition with increased muscle mass and reduced fat mass. In conclusion, TWK10 demonstrates superior longevous and ergogenic effects in C. elegans compared to reference strains. The consistent ergogenic efficacy of mass-produced TWK10 across C. elegans, mice, and humans, highlights the utility of C. elegans as a reliable model for probiotic research and industrial application.

Insulin-Like Growth Factor Signaling in Alzheimer's Disease: Pathophysiology and Therapeutic Strategies

Alzheimer's disease (AD) is the leading cause of dementia among the elderly population, posing a significant public health challenge due to limited therapeutic options that merely delay cognitive decline. AD is associated with impaired energy metabolism and reduced neurotrophic signaling. The insulin-like growth factor (IGF) signaling pathway, crucial for central nervous system (CNS) development, metabolism, repair, cognition, and emotion regulation, includes IGF-1, IGF-2, IGF-1R, IGF-2R, insulin receptor (IR), and six insulin-like growth factor binding proteins (IGFBPs). Research has identified abnormalities in IGF signaling in individuals with AD and AD models. Dysregulated expression of IGFs, receptors, IGFBPs, and disruptions in downstream phosphoinositide 3-kinase-protein kinase B (PI3K/AKT) and mitogen-activated protein kinase (MAPK) pathways collectively increase AD susceptibility. Studies suggest modulating the IGF pathway may ameliorate AD pathology and cognitive decline. This review explores the CNS pathophysiology of IGF signaling in AD progression and assesses the potential of targeting the IGF system as a novel therapeutic strategy. Further research is essential to elucidate how aberrant IGF signaling contributes to AD development, understand underlying molecular mechanisms, and evaluate the safety and efficacy of IGF-based treatments.

Adapting Caenorhabditis elegans to evaluating functional foods and ingredients for cholesterol absorption

The nematode Caenorhabditis elegans is an excellent model organism for elucidating higher life phenomena. C. elegans and humans are common in many aspects. During our research on development and life span regulation, we identified RAB-18, a small guanosine triphosphatase (GTPase) involved in the membrane trafficking of NCR-1, a cholesterol transporter mainly expressed in the intestine. We expressed the human NPC1L1, an intestinal cholesterol transporter, in mutant C. elegans lacking NCR-1. NPC1L1-expressing animals revealed almost the same larval diapause in the presence of a diapause-inducing pheromone and lipid droplets containing cholesterol as in wild-type C. elegans. This result indicates that C. elegans NCR-1 and human NPC1L1 are exchangeable and that C. elegans RAB-18 transports human NPC1L1 to the apical membrane in the C. elegans intestine. This transgenic C. elegans could be adapted to evaluate functional foods and ingredients regarding cholesterol absorption.

The forkhead transcription factor FKH-7/FOXP acts in chemosensory neurons to regulate developmental decision-making

Autism is a complex neurodevelopmental disorder with many associated genetic factors, including the forkhead transcription factor FOXP1. Although FOXP1's neuronal role is well-studied, the specific molecular consequences of different FOXP1 pathogenic variants in physiologically-relevant contexts are unknown. Here we ascribe the first function to Caenorhabditis elegans FKH-7/FOXP, which acts in two chemosensory neuron classes to promote the larval decision to enter the alternative, developmentally-arrested dauer life stage. We demonstrate that human FOXP1 can functionally substitute for C. elegans FKH-7 in these neurons and that engineering analogous FOXP1 hypomorphic missense mutations in the endogenous fkh-7 locus also impairs developmental decision-making. In a fkh-7/FOXP1 missense variant, single-cell transcriptomics identifies downregulated expression of autism-associated kcnl-2/KCNN2 calcium-activated potassium channel in a serotonergic sensory neuron. Our findings establish a novel framework linking two evolutionarily-conserved autism-associated genes for deeper characterization of variant-specific molecular pathology at single neuron resolution in the context of a developmental decision-making paradigm.

fmo-4 promotes longevity and stress resistance via ER to mitochondria calcium regulation in C. elegans

Flavin-containing monooxygenases (FMOs) are a conserved family of xenobiotic enzymes upregulated in multiple longevity interventions, including nematode and mouse models. Previous work supports that C. elegans fmo-2 promotes longevity, stress resistance, and healthspan by rewiring endogenous metabolism. However, there are five C. elegans FMOs and five mammalian FMOs, and it is not known whether promoting longevity and health benefits is a conserved role of this gene family. Here, we report that expression of C. elegans fmo-4 promotes lifespan extension and paraquat stress resistance downstream of both dietary restriction and inhibition of mTOR. We find that overexpression of fmo-4 in just the hypodermis is sufficient for these benefits, and that this expression significantly modifies the transcriptome. By analyzing changes in gene expression, we find that genes related to calcium signaling are significantly altered downstream of fmo-4 expression. Highlighting the importance of calcium homeostasis in this pathway, fmo-4 overexpressing animals are sensitive to thapsigargin, an ER stressor that inhibits calcium flux from the cytosol to the ER lumen. This calcium/fmo-4 interaction is solidified by data showing that modulating intracellular calcium with either small molecules or genetics can change expression of fmo-4 and/or interact with fmo-4 to affect lifespan and stress resistance. Further analysis supports a pathway where fmo-4 modulates calcium homeostasis downstream of activating transcription factor-6 (atf-6), whose knockdown induces and requires fmo-4 expression. Together, our data identify fmo-4 as a longevity-promoting gene whose actions interact with known longevity pathways and calcium homeostasis.

N. sphaeroides phycocyanin subunit Ns-α and Ns-β improve C. elegans antioxidative capacity via ROS-related regulation

Oxidative stress and damage to macromolecules due to free radicals such as reactive oxygen species (ROS) are commonly considered factors that can impair health. This study investigated the potential antioxidant properties of of two subunit proteins associated with the pigment-protein complex phycocyanin derived from Nostoc sphaeroides (Gexianmi). Bacterial expression vectors were separately constructed to induce the two engineering subunit proteins, Ns-α and Ns-β. These engineering proteins were then examined for their potential to enhance antioxidative capacity in Caenorhabditis elegans. Firstly, a proper concentration of the proteins Ns-α and Ns-β in vitro exhibited 2, 2-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activity. Secondly, while there were no other observed effects on the nematodes, those treated with the proteins showed significant improvements in motility and reduced levels of lipofuscin compared to the control group. Furthermore, thirdly, the treated nematodes demonstrated increased resistance to oxidation, as evidenced by the higher survivals under oxidative conditions induced by 5 mM H2O2. Notably, the treated nematodes exhibited decline in endogenous ROS levels, and the redox-related genes, such as SOD-3 and CAT-1, were down-regulated following consumption of the engineering proteins. Taken together, these findings suggest that engineering proteins Ns-α and Ns-β improve the antioxidative capacity of C. elegans by modulating ROS-related regulation, making them potential modulators in responding to oxidative stressors.

Suppressing APOE4-induced neural pathologies by targeting the VHL-HIF axis

The ε4 variant of human apolipoprotein E (APOE4) is a key genetic risk factor for neurodegeneration in Alzheimer's disease and elevated all-cause mortality in humans. Understanding the factors and mechanisms that can mitigate the harmful effects of APOE4 has significant implications. In this study, we find that inactivating the VHL-1 (Von Hippel-Lindau) protein can suppress mortality, neural and behavioral pathologies caused by transgenic human APOE4 in Caenorhabditis elegans. The protective effects of VHL-1 deletion are recapitulated by stabilized HIF-1 (hypoxia-inducible factor), a transcription factor degraded by VHL-1. HIF-1 activates a genetic program that safeguards against mitochondrial dysfunction, oxidative stress, proteostasis imbalance, and endolysosomal rupture-critical cellular events linked to neural pathologies and mortality. Furthermore, genetic inhibition of Vhl reduces cerebral vascular injury and synaptic lesions in APOE4 mice, suggesting an evolutionarily conserved mechanism. Thus, we identify the VHL-HIF axis as a potent modulator of APOE4-induced neural pathologies and propose that targeting this pathway in nonproliferative tissues may curb cellular damage, protect against neurodegeneration, and reduce tissue injuries and mortality.

SRS microscopy identifies inhibition of vitellogenesis as a mediator of lifespan extension by caloric restriction in C. elegans

The molecular mechanisms of aging are not fully understood. Here, we used label-free Stimulated Raman scattering (SRS) microscopy to investigate changes in proteins and lipids throughout the lifespan of C. elegans. We observed a dramatic buildup of proteins within the body cavity or pseudocoelom of aged adults that was blunted by interventions that extend lifespan: caloric restriction (CR) and the reduced insulin/insulin-like growth factor signaling (IIS) pathway. Using a combination of microscopy, proteomic analysis, and validation with mutant strains, we identified vitellogenins as the key molecular components of the protein buildup in the pseudocoelom. Vitellogenins shuttle nutrients from intestine to embryos and are homologous to human apolipoprotein B, the causal driver of cardiovascular disease. We then showed that CR and knockdown of vitellogenins both extend lifespan by >60%, but their combination has no additional effect on lifespan, suggesting that CR extends the lifespan of C. elegans in part by inhibiting vitellogenesis. The extensive dataset of more than 12,000 images stitched into over 350 whole-animal SRS images of C. elegans at different ages and subjected to different longevity intervention will be a valuable resource for researchers interested in aging.

Temperature Acclimation and Cold Tolerance in Caenorhabditis Elegans are Regulated by Multiorgan Coordination

To ensure survival and reproduction, organisms must continually adapt to environmental fluctuations, such as temperature, humidity, oxygen level, and salinity. Particularly, temperature profoundly influences biochemical reactions crucial for survival. Here, we present the mechanisms employed by the nematode Caenorhabditis elegans to anticipate and respond to cold temperatures. Our findings reveal that temperature is detected by specific neurons linked to various physiological processes in the gut, spermatheca, and muscles. Notably, the gut, a primary fat storage organ in C. elegans, regulates fat mobilization and accumulation in a temperature-dependent manner, thereby contributing to temperature adaptation. Furthermore, normal spermatogenetic mechanisms influence cold tolerance by modulating the responsiveness of thermosensory neurons to temperature changes. Considering our results together with recent reports, we suggest that a polyU-specific endoribonuclease expressed in muscle cells plays a role in cold tolerance through a non-cell-autonomous mechanism, possibly involving transportation intertissues. Thus, understanding cold tolerance and temperature acclimation in C. elegans can provide valuable insights on systemic physiological regulation in response to temperature fluctuations. Moreover, they could help elucidate the actions of thermosensory neurons and their downstream neuronal circuits or neuropeptides on the peripheral organs.

The signaling landscape of insulin-like growth factor 1

The sheer amplitude of biological actions of insulin-like growth factor I (IGF-1) affecting all types of cells in all tissues suggests a vast signaling landscape for this ubiquitous humoral signal. While the canonical signaling pathways primarily involve the Ras/MAPK and PI3K/AKT cascades, the evolutionary conservation of insulin-like peptides (ILPs) and their pathways hints at the potential for novel functions to emerge over time. Indeed, the evolutionary trajectory of ILPs opens the possibility of either novel functions for these two pathways, novel downstream routes, or both. Evidence supporting this notion includes observations of neofunctionalization in bony fishes or crustaceans, and the involvement of ILPs pathways in invertebrate eusociality or in vertebrate bone physiology, respectively. Such evolutionary processes likely contribute to the rich diversity of ILPs signaling observed today. Moreover, the interplay between conserved signaling pathways, such as those implicated in aging (predominantly involving the PI3K-AKT route), and lesser known pathways, such as those mediated by biased G-protein coupled receptors and others even less known, may underpin the context-dependent actions characteristic of ILPs signaling. While canonical IGF-1 signaling is often assumed to account for the intracellular pathways utilized by this growth factor, a comprehensive analysis of all the pathways mediated by the IGF-1 receptor (IGF-1R) remains lacking. This review aims to explore both canonical and non-canonical routes of IGF-1R action across various cell types, offering a detailed examination of the mechanisms underlying IGF-1 signaling and highlighting the significant gaps in our current understanding.

Dynamic Changes in Gene Expression Through Aging in Drosophila melanogaster Heads

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

Dog Aging: A Comprehensive Review of Molecular, Cellular, and Physiological Processes

The aging process is a multifactorial biological phenomenon starting at birth and persisting throughout life, characterized by a decline in physiological functions and adaptability. This decline results in the diminished capacity of aging organisms to respond to environmental changes and stressors, leading to reduced efficiency in metabolic, immune, and hormonal functions. As behavioral flexibility wanes, older individuals face longer recovery times and increased vulnerability to diseases. While early research proposed nine core hallmarks of mammalian aging, recent studies have expanded this framework to twelve key characteristics: epigenetic changes, genomic instability, telomere shortening, loss of proteostasis, altered metabolism, mitochondrial dysfunction, cellular senescence, disrupted intercellular communication, stem cell depletion, immune system dysfunction, accumulation of toxic metabolites, and dysbiosis. Given the growing interest in the aging area, we propose to add a new hallmark: impaired water homeostasis. This potential hallmark could play a critical role in aging processes and might open new directions for future research in the field. This review enhances our understanding of the physiological aspects of aging in dogs, suggesting new clinical intervention strategies to prevent and control issues that may arise from the pathological degeneration of these hallmarks.

Low methyl-esterified ginseng homogalacturonan pectins promote longevity of Caenorhabditis elegans via impairing insulin/IGF-1 signalling

Panax ginseng C. A. Meyer (ginseng) is a medicinal plant widely used for promoting longevity. Recently, homogalacturonan (HG) domain-rich pectins purified from some plants have been reported to have anti-aging-related activities, leading us to explore the longevity-promoting activity of the HG pectins from ginseng. In this study, we discovered that two of low methyl-esterified ginseng HG pectins (named as WGPA-2-HG and WGPA-3-HG), whose degree of methyl-esterification (DM) was 16 % and 8 % respectively, promoted longevity in Caenorhabditis elegans. Results showed that WGPA-2-HG/WGPA-3-HG impaired insulin/insulin-like growth factor 1 (IGF-1) signalling (IIS) pathway, thereby increasing the nuclear accumulation of transcription factors SKN-1/Nrf2 and DAF-16/FOXO and enhancing the expression of relevant anti-aging genes. BLI and ITC analysis showed that the insulin-receptor binding, the first step to activate IIS pathway, was impeded by the engagement of WGPA-2-HG/WGPA-3-HG with insulin. By chemical modifications, we found that high methyl-esterification of WGPA-2-HG/WGPA-3-HG was detrimental for their longevity-promoting activity. These findings provided novel insight into the precise molecular mechanism for the longevity-promoting effect of ginseng pectins, and suggested a potential to utilize the ginseng HG pectins with appropriate DM values as natural nutrients for increasing human longevity.

The 2024 Nobel Prize in Physiology or Medicine: microRNA Takes Center Stage

The Non-coding Journal Editorial Board Members would like to congratulate Victor Ambros and Gary Ruvkun, who were jointly awarded the 2024 Nobel Prize in Physiology or Medicine for their groundbreaking discovery of microRNAs and the role of microRNAs in post-transcriptional gene regulation, uncovering a previously unknown layer of gene control in eukaryotes [...].

Catalytic activities of wild-type C. elegans DAF-2 kinase and dauer-associated mutants

DAF-2, the Caenorhabditis elegans insulin-like receptor homolog, regulates larval development, metabolism, stress response, and lifespan. The availability of numerous daf-2 mutant alleles has made it possible to elucidate the genetic mechanisms underlying these physiological processes. The DAF-2 pathway is significantly conserved with the human insulin/IGF-1 signaling pathway; it includes proteins homologous to human IRS, GRB-2, and PI3K, making it an important model to investigate human pathological conditions. We expressed and purified the kinase domain of wild-type DAF-2 to examine the catalytic activity and substrate specificity of the enzyme. Like the human insulin receptor kinase, DAF-2 kinase phosphorylates tyrosines within specific YxN or YxxM motifs, which are important for recruiting downstream effectors. DAF-2 kinase phosphorylated peptides derived from the YxxM and YxN motifs located in the C-terminal extension of the receptor tyrosine kinase, consistent with the idea that the DAF-2 receptor may possess independent signaling capacity. Unlike the human insulin or IGF-1 receptor kinases, DAF-2 kinase was poorly inhibited by the small-molecule inhibitor linsitinib. We also expressed and purified mutant kinases corresponding to daf-2 alleles that result in partial loss-of-function phenotypes in C. elegans. These mutations caused a complete loss of kinase function in vitro. Our biochemical investigations provide new insights into DAF-2 kinase function, and the approach should be useful for studying other mutations to shed light on DAF-2 signaling in C. elegans physiology.

Non-autonomous insulin signaling delays mitotic progression in C. elegans germline stem and progenitor cells

Stem and progenitor cell mitosis is essential for tissue development and homeostasis. How these cells ensure proper chromosome segregation, and thereby maintain mitotic fidelity, in the complex physiological environment of a living animal is poorly understood. Here we use in situ live-cell imaging of C. elegans germline stem and progenitor cells (GSPCs) to ask how the signaling environment influences stem and progenitor cell mitosis in vivo. Through a candidate screen we identify a new role for the insulin/IGF receptor (IGFR), daf-2, during GSPC mitosis. Mitosis is delayed in daf-2/IGFR mutants, and these delays require canonical, DAF-2/IGFR to DAF-16/FoxO insulin signaling, here acting cell non-autonomously from the soma. Interestingly, mitotic delays in daf-2/IGFR mutants depend on the spindle assembly checkpoint but are not accompanied by a loss of mitotic fidelity. Correspondingly, we show that caloric restriction, which delays GSPC mitosis and compromises mitotic fidelity, does not act via the canonical insulin signaling pathway, and instead requires AMP-activated kinase (AMPK). Together this work demonstrates that GSPC mitosis is influenced by at least two genetically separable signaling pathways and highlights the importance of signaling networks for proper stem and progenitor cell mitosis in vivo.

Lipotoxicity of palmitic acid is associated with DGAT1 downregulation and abolished by PPARα activation in liver cells

Lipotoxicity refers to the harmful effects of excess fatty acids on metabolic health, and it can vary depending on the type of fatty acids involved. Saturated and unsaturated fatty acids exhibit distinct effects, though the precise mechanisms behind these differences remain unclear. Here, we investigated the lipotoxicity of palmitic acid (PA), a saturated fatty acid, compared with oleic acid (OA), a monounsaturated fatty acid, in the hepatic cell line HuH7. Our results demonstrated that PA, unlike OA, induces lipotoxicity, endoplasmic reticulum (ER) stress, and autophagy inhibition. Compared with OA, PA treatment leads to less lipid droplet (LD) accumulation and a significant reduction in the mRNA and protein level of diacylglycerol acyltransferase 1 (DGAT1), a key enzyme of triacylglycerol synthesis. Using modulators of ER stress and autophagy, we established that DGAT1 downregulation by PA is closely linked to these cellular pathways. Notably, the ER stress inhibitor 4-phenylbutyrate can suppress PA-induced DGAT1 downregulation. Furthermore, knockdown of DGAT1 by siRNA or with A922500, a specific DGAT1 inhibitor, resulted in cell death, even with OA. Both PA and OA increased the oxygen consumption rate; however, the increase associated with PA was only partially coupled to ATP synthesis. Importantly, treatment with GW7647 a specific PPARα agonist mitigated the lipotoxic effects of PA, restoring PA-induced ER stress, autophagy block, and DGAT1 suppression. In conclusion, our study highlights the crucial role of DGAT1 in PA-induced lipotoxicity, broadening the knowledge of the mechanisms underlying hepatic lipotoxicity and providing the basis for potential therapeutic interventions.

Lifespan Extension and Motor Function Improvement Effects of Whale Meat Extract in Caenorhabditis elegans

The average life expectancy is increasing worldwide, but the same cannot be said for a healthy life expectancy (defined as the period during which a person can live a healthy and independent life). Therefore, a major challenge is how to extend healthy life expectancy. One option is to reduce age-related muscle atrophy (sarcopenia) and cognitive decline. Since there is no specific cure for frailty, the prevention of frailty based on nutrition and exercise is a new approach to achieve healthy longevity. Studies have shown that interventions combining nutritional supplements and exercise are effective in improving muscle strength, muscle mass, and walking speed. Thus, the search for drugs and functional foods to combat frailty has attracted researchers' attention. Whale meat extract (WME) contains many imidazole dipeptides, especially the unique component balenine, which has various functional anti-fatigue and antioxidant properties, and hypermobility effects. Here, we investigated the effects of WME on the aging and health of Caenorhabditis elegans (hereafter, C. elegans). mRNA expression analysis showed that WME prolongs the lifespan of C. elegans mainly through sir-2.1, daf-2, and daf-16, and the myo-3, unc-54, unc-22, and fhod-1 genes involved in locomotor function. The results of this study showed that the expression of the antioxidant enzymes sod-2 and sod-3 was also increased. This study may provide the basis for further research on WME as a food and supplement to slow aging and improve motor function.

A mitochondrial unfolded protein response-independent role of DVE-1 in longevity regulation

The special AT-rich sequence-binding (SATB) protein DVE-1 is widely recognized for its pivotal involvement in orchestrating the retrograde mitochondrial unfolded protein response (mitoUPR) in C. elegans. In our study of downstream factors contributing to lifespan extension in sensory ciliary mutants, we find that DVE-1 is crucial for this longevity effect independent of its canonical mitoUPR function. Additionally, DVE-1 also influences lifespan under conditions of dietary restriction and germline loss, again distinct from its role in mitoUPR. Mechanistically, while mitochondrial stress typically prompts nuclear accumulation of DVE-1 to initiate the transcriptional mitoUPR program, these long-lived mutants reduce DVE-1 nuclear accumulation, likely by enhancing its cytosolic translocation. This observation suggests a cytosolic role for DVE-1 in lifespan extension. Overall, our study implies that, in contrast to the more narrowly defined role of the mitoUPR-related transcription factor ATFS-1, DVE-1 may possess broader functions than previously recognized in modulating longevity and defending against stress.

mTOR activity paces human blastocyst stage developmental progression

Many mammals can temporally uncouple conception from parturition by pacing down their development around the blastocyst stage. In mice, this dormant state is achieved by decreasing the activity of the growth-regulating mTOR signaling pathway. It is unknown whether this ability is conserved in mammals in general and in humans in particular. Here, we show that decreasing the activity of the mTOR signaling pathway induces human pluripotent stem cells (hPSCs) and blastoids to enter a dormant state with limited proliferation, developmental progression, and capacity to attach to endometrial cells. These in vitro assays show that, similar to other species, the ability to enter dormancy is active in human cells around the blastocyst stage and is reversible at both functional and molecular levels. The pacing of human blastocyst development has potential implications for reproductive therapies.

fmo-4 promotes longevity and stress resistance via ER to mitochondria calcium regulation in C. elegans

Flavin-containing monooxygenases (FMOs) are a conserved family of xenobiotic enzymes upregulated in multiple longevity interventions, including nematode and mouse models. Previous work supports that C. elegans fmo-2 promotes longevity, stress resistance, and healthspan by rewiring endogenous metabolism. However, there are five C. elegans FMOs and five mammalian FMOs, and it is not known whether promoting longevity and health benefits is a conserved role of this gene family. Here, we report that expression of C. elegans fmo-4 promotes lifespan extension and paraquat stress resistance downstream of both dietary restriction and inhibition of mTOR. We find that overexpression of fmo-4 in just the hypodermis is sufficient for these benefits, and that this expression significantly modifies the transcriptome. By analyzing changes in gene expression, we find that genes related to calcium signaling are significantly altered downstream of fmo-4 expression. Highlighting the importance of calcium homeostasis in this pathway, fmo-4 overexpressing animals are sensitive to thapsigargin, an ER stressor that inhibits calcium flux from the cytosol to the ER lumen. This calcium/fmo-4 interaction is solidified by data showing that modulating intracellular calcium with either small molecules or genetics can change expression of fmo-4 and/or interact with fmo-4 to affect lifespan and stress resistance. Further analysis supports a pathway where fmo-4 modulates calcium homeostasis downstream of activating transcription factor-6 (atf-6), whose knockdown induces and requires fmo-4 expression. Together, our data identify fmo-4 as a longevity-promoting gene whose actions interact with known longevity pathways and calcium homeostasis.

Life history in Caenorhabditis elegans: from molecular genetics to evolutionary ecology

Life history is defined by traits that reflect key components of fitness, especially those relating to reproduction and survival. Research in life history seeks to unravel the relationships among these traits and understand how life history strategies evolve to maximize fitness. As such, life history research integrates the study of the genetic and developmental mechanisms underlying trait determination with the evolutionary and ecological context of Darwinian fitness. As a leading model organism for molecular and developmental genetics, Caenorhabditis elegans is unmatched in the characterization of life history-related processes, including developmental timing and plasticity, reproductive behaviors, sex determination, stress tolerance, and aging. Building on recent studies of natural populations and ecology, the combination of C. elegans' historical research strengths with new insights into trait variation now positions it as a uniquely valuable model for life history research. In this review, we summarize the contributions of C. elegans and related species to life history and its evolution. We begin by reviewing the key characteristics of C. elegans life history, with an emphasis on its distinctive reproductive strategies and notable life cycle plasticity. Next, we explore intraspecific variation in life history traits and its underlying genetic architecture. Finally, we provide an overview of how C. elegans has guided research on major life history transitions both within the genus Caenorhabditis and across the broader phylum Nematoda. While C. elegans is relatively new to life history research, significant progress has been made by leveraging its distinctive biological traits, establishing it as a highly cross-disciplinary system for life history studies.

The combination of metformin and high glucose increased longevity of Caenorhabditis elegans a DAF-16/FOXO-independent manner: cancer/diabetic model via C. elegans

Introduction

Sedentary lifestyles and diets with high glycemic indexes are considered to be contributing factors to the development of obesity, type 2 diabetes in humans. Metformin, a biguanide medication commonly used to treat type 2 diabetes, has been observed to be associated with longevity; however, the molecular mechanisms underlying this observation are still unknown.

Methods

The effects of metformin and high glucose, which have important roles in aging-related disease such as diabetes and cancer, were studied in lin-35 worms because they are associated with cancer-associated pRb function in mammals and have a tumour suppressor property.

Results and Discussion

According to our results, the negative effect of high glucose on egg production of lin-35 worms was greater than that of N2 worms. High glucose shortened lifespan and increased body length and width in individuals of both strains. Metformin treatment alone extended the lifespan of N2 and lin-35 worms by reducing fertilization efficiency. However, when metformin was administered in the presence of high glucose, the lifespan of lin-35 worms was clearly longer compared to N2 worms. Additionally, we conclude that glucose and metformin in lin35 worms can extend life expectancy through a DAF-16/FOXO-independent mechanism. Furthermore, the results of this study will provide a new perspective on extending mammalian lifespan through the model organism C. elegans.

The Fourth Annual Symposium of the Midwest Aging Consortium

The Midwest Aging Consortium (MAC) has emerged as a critical collaborative initiative aimed at advancing our understanding of aging and developing strategies to combat the rising prevalence of age-related diseases. Founded in 2019, MAC brings together researchers from various disciplines and institutions across the Midwestern United States to foster interdisciplinary geroscience research. This report summarizes the highlights of the Fourth Annual Symposium of MAC, which was held at Iowa State University in May 2023. The symposium featured presentations on a wide array of topics, including studies on slow-aging animals, cellular senescence and senotherapeutics, the role of the immune system in aging, metabolic changes in aging, neuronal health in aging, and biomarkers for measuring the aging process. Speakers shared findings from studies involving a variety of animals, ranging from commonly used species such as mice, rats, worms, yeast, and fruit flies, to less-common ones like naked mole-rats, painted turtles, and rotifers. MAC continues to emphasize the importance of supporting emerging researchers and fostering a collaborative environment, positioning itself as a leader in aging research. This symposium not only showcased the current state of aging biology research but also highlighted the consortium's role in training the next generation of scientists dedicated to improving the healthspan and well-being of the aging population.

β-asarone protects against age-related motor decline via activation of SKN-1/Nrf2 and subsequent induction of GST-4

Decelerating motor decline is important for promoting healthy aging in the elderly population. Acorus tatarinowii Schott is a traditional Chinese medicine that contains β-asarone as a pharmacologically active constituent. We found that β-asarone can decelerate motor decline in various age groups of Caenorhabditis elegans, while concurrently prolonging their lifespan and modulating synaptic transmission. To understand the mechanisms of its efficacy in motor improvement, we investigated and discovered that mitochondrial fragmentation, a marker for aging, is delayed after β-asarone treatment. Moreover, their efficacy is blocked by dysfunctional mitochondria. Corresponding to their role in regulating mitochondrial homeostasis, we found that SKN-1/Nrf2 and GST-4 are critical in the β-asarone treatment, and they appear to be activated via the insulin/IGF-1 signaling pathway. Well-developed intestinal microvilli are required for this process. Our study demonstrates the efficacy and mechanism of β-asarone treatment in age-related motor decline, contributing to the discovery of drugs for achieving healthy aging.

Identification and Characterization of a Novel Insulin-like Receptor (LvRTK2) Involved in Regulating Growth and Glucose Metabolism of the Pacific White Shrimp Litopenaeus vannamei

The insulin receptor (IR) plays a crucial role in the growth and metabolism of animals. However, there are still many questions regarding the IR in crustaceans, particularly their role in shrimp growth and glucose metabolism. In this study, we identified a novel insulin-like receptor gene in Litopenaeus vannamei and cloned its full length of 6439 bp. This gene exhibited a highly conserved sequence and structural characteristics. Phylogenetic analysis confirmed it as an unreported RTK2-type IR, namely, LvRTK2. Expression pattern analysis showed that LvRTK2 is primarily expressed in female reproductive and digestive organs. Through a series of in vivo and in vitro experiments, including glucose treatment, exogenous insulin treatment, and starvation treatment, LvRTK2 was confirmed to be involved in the endogenous glucose metabolic pathway of shrimp under different glucose variations. Moreover, long-term and short-term interference experiments with LvRTK2 revealed that the interference significantly reduced the shrimp growth rate and serum glucose clearance rate. Further studies indicated that LvRTK2 may regulate shrimp growth by modulating the downstream PI3K/AKT signaling pathway and a series of glucose metabolism events, such as glycolysis, gluconeogenesis, glycogen synthesis, and glycogenolysis. This report on the characteristics and functions of LvRTK2 confirms the important role of RTK2-type IRs in regulating shrimp growth and glucose metabolism.

Improved resilience and proteostasis mediate longevity upon DAF-2 degradation in old age

Little is known about the possibility of reversing age-related biological changes when they have already occurred. To explore this, we have characterized the effects of reducing insulin/IGF-1 signaling (IIS) during old age. Reduction of IIS throughout life slows age-related decline in diverse species, most strikingly in the nematode Caenorhabditis elegans. Here we show that even at advanced ages, auxin-induced degradation of DAF-2 in single tissues, including neurons and the intestine, is still able to markedly increase C. elegans lifespan. We describe how reversibility varies among senescent changes. While senescent pathologies that develop in mid-life were not reversed, there was a rejuvenation of the proteostasis network, manifesting as a restoration of the capacity to eliminate otherwise intractable protein aggregates that accumulate with age. Moreover, resistance to several stressors was restored. These results support several new conclusions. (1) Loss of resilience is not solely a consequence of pathologies that develop in earlier life. (2) Restoration of proteostasis and resilience by inhibiting IIS is a plausible cause of the increase in lifespan. And (3), most interestingly, some aspects of the age-related transition from resilience to frailty can be reversed to a certain extent. This raises the possibility that the effect of IIS and related pathways on resilience and frailty during aging in higher animals might possess some degree of reversibility.

Caenorhabditis elegans as a Model to Study Aging and Photoaging

Caenorhabditis elegans (C. elegans) has emerged as an outstanding model organism for investigating the aging process due to its shortened lifespan, well-defined genome, and accessibility of potent genetic tools. This review presents the current findings on chronological aging and photoaging in C. elegans, exploring the elaborate molecular pathways that control these processes. The progression of chronological aging is characterized by a gradual deterioration of physiological functions and is influenced by an interaction of genetic and environmental factors, including the insulin/insulin-like signaling (IIS) pathway. In contrast, photoaging is characterized by increased oxidative stress, DNA damage, and activation of stress response pathways induced by UV exposure. Although the genetic mechanisms of chronological aging in C. elegans have been characterized by extensive research, the pathways regulating photoaging are comparatively less well-studied. Here, we provide an overview of the current understanding of aging research, including the crucial genes and genetic pathways involved in the aging and photoaging processes of C. elegans. Understanding the complex interactions between these factors will provide invaluable insights into the molecular mechanisms underlying chronological aging and photoaging and may lead to novel therapeutic approaches and further studies for promoting healthy aging in humans.

Targeting Cell Senescence and Senolytics: Novel Interventions for Age-Related Endocrine Dysfunction

Multiple changes occur in hormonal regulation with aging and across various endocrine organs. These changes are associated with multiple age-related disorders and diseases. A better understanding of responsible underling biological mechanisms could help in the management of multiple endocrine disorders over and above hormone replacement therapy (HRT). Cellular senescence is involved in multiple biological aging processes and pathologies common in elderly individuals. Cellular senescence, which occurs in many older individuals but also across the lifespan in association with tissue damage, acute and chronic diseases, certain drugs, and genetic syndromes, may contribute to such endocrine disorders as osteoporosis, metabolic syndrome, and type 2 diabetes mellitus. Drugs that selectively induce senescent cell removal, "senolytics,", and drugs that attenuate the tissue-destructive secretory state of certain senescent cells, "senomorphics," appear to delay the onset of or alleviate multiple diseases, including but not limited to endocrine disorders such as diabetes, complications of obesity, age-related osteoporosis, and cancers as well as atherosclerosis, chronic kidney disease, neurodegenerative disorders, and many others. More than 30 clinical trials of senolytic and senomorphic agents have already been completed, are underway, or are planned for a variety of indications. Targeting senescent cells is a novel strategy that is distinct from conventional therapies such as HRT, and thus might address unmet medical needs and can potentially amplify effects of established endocrine drug regimens, perhaps allowing for dose decreases and reducing side effects.

Behavioral plasticity

Behavioral plasticity allows animals to modulate their behavior based on experience and environmental conditions. Caenorhabditis elegans exhibits experience-dependent changes in its behavioral responses to various modalities of sensory cues, including odorants, salts, temperature, and mechanical stimulations. Most of these forms of behavioral plasticity, such as adaptation, habituation, associative learning, and imprinting, are shared with other animals. The C. elegans nervous system is considerably tractable for experimental studies-its function can be characterized and manipulated with molecular genetic methods, its activity can be visualized and analyzed with imaging approaches, and the connectivity of its relatively small number of neurons are well described. Therefore, C. elegans provides an opportunity to study molecular, neuronal, and circuit mechanisms underlying behavioral plasticity that are either conserved in other animals or unique to this species. These findings reveal insights into how the nervous system interacts with the environmental cues to generate behavioral changes with adaptive values.

Spermidine is essential for fasting-mediated autophagy and longevity

Caloric restriction and intermittent fasting prolong the lifespan and healthspan of model organisms and improve human health. The natural polyamine spermidine has been similarly linked to autophagy enhancement, geroprotection and reduced incidence of cardiovascular and neurodegenerative diseases across species borders. Here, we asked whether the cellular and physiological consequences of caloric restriction and fasting depend on polyamine metabolism. We report that spermidine levels increased upon distinct regimens of fasting or caloric restriction in yeast, flies, mice and human volunteers. Genetic or pharmacological blockade of endogenous spermidine synthesis reduced fasting-induced autophagy in yeast, nematodes and human cells. Furthermore, perturbing the polyamine pathway in vivo abrogated the lifespan- and healthspan-extending effects, as well as the cardioprotective and anti-arthritic consequences of fasting. Mechanistically, spermidine mediated these effects via autophagy induction and hypusination of the translation regulator eIF5A. In summary, the polyamine-hypusination axis emerges as a phylogenetically conserved metabolic control hub for fasting-mediated autophagy enhancement and longevity.

A homeostatic gut-to-brain insulin antagonist restrains neuronally stimulated fat loss

In C. elegans mechanisms by which peripheral organs relay internal state information to the nervous system remain unknown, although strong evidence suggests that such signals do exist. Here we report the discovery of a peptide of the ancestral insulin superfamily called INS-7 that functions as an enteroendocrine peptide and is secreted from specialized cells of the intestine. INS-7 secretion is stimulated by food withdrawal, increases during fasting and acts as a bona fide gut-to-brain peptide that attenuates the release of a neuropeptide that drives fat loss in the periphery. Thus, INS-7 functions as a homeostatic signal from the intestine that gates the neuronal drive to stimulate fat loss during food shortage. Mechanistically, INS-7 functions as an antagonist at the canonical DAF-2 receptor and functions via FOXO and AMPK signaling in ASI neurons. Phylogenetic analysis suggests that INS-7 bears greater resemblance to members of the broad insulin/relaxin superfamily than to conventional mammalian insulin and IGF peptides. The discovery of an endogenous insulin antagonist secreted by specialized intestinal cells with enteroendocrine functions suggests unexpected and important properties of the intestine and its role in directing neuronal functions.