The Fork head transcription factor DAF-16 transduces insulin-like metabolic and longevity signals in C. elegans

DAF-18/PTEN protects LIN-35/Rb from CLP-1/CAPN-mediated cleavage to promote starvation resistance

Starvation resistance is a fundamental trait with profound influence on fitness and disease risk. DAF-18, the Caenorhabditis elegans ortholog of the tumor suppressor PTEN, promotes starvation resistance. PTEN is a dual phosphatase, and DAF-18 promotes starvation resistance as a lipid phosphatase by antagonizing insulin/IGF and PI3K signaling, activating the tumor suppressor DAF-16/FoxO. However, if or how DAF-18/PTEN protein-phosphatase activity promotes starvation resistance is unknown. Using genetic, genomic, bioinformatic, and biochemical approaches, we identified the C. elegans retinoblastoma/RB protein homolog, LIN-35/Rb, as a critical mediator of the effect of DAF-18/PTEN on starvation resistance. We show that DAF-18/PTEN protects LIN-35/Rb from cleavage by the μ-Calpain homolog CLP-1/CAPN, and that LIN-35/Rb together with the repressive DREAM complex promotes starvation resistance. We conclude that the tumor suppressors DAF-18/PTEN and LIN-35/Rb function in a linear pathway, with LIN-35/Rb and the rest of the DREAM complex functioning as a transcriptional effector of DAF-18/PTEN protein-phosphatase activity resulting in repression of germline gene expression. This work is significant for revealing a network of tumor suppressors that promote survival during cellular and developmental quiescence.

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.

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.

DAF-18/PTEN protects LIN-35/Rb from CLP-1/CAPN-mediated cleavage to promote starvation resistance

Starvation resistance is a fundamental trait with profound influence on fitness and disease risk. DAF-18, the C. elegans ortholog of the tumor suppressor PTEN, promotes starvation resistance. PTEN is a dual phosphatase, and DAF-18 promotes starvation resistance as a lipid phosphatase by antagonizing insulin/IGF and PI3K signaling, activating the tumor suppressor DAF-16/FoxO. However, if or how DAF-18/PTEN protein-phosphatase activity promotes starvation resistance is unknown. Using genetic, genomic, bioinformatic, and biochemical approaches, we identified the C. elegans retinoblastoma/RB protein homolog, LIN-35/Rb, as a critical mediator of the effect of DAF-18/PTEN on starvation resistance. We show that DAF-18/PTEN protects LIN-35/Rb from cleavage by the μ-Calpain homolog CLP-1/CAPN, and that LIN-35/Rb together with the repressive DREAM complex promote starvation resistance. We conclude that the tumor suppressors DAF-18/PTEN and LIN-35/Rb function in a linear pathway, with LIN-35/Rb and the rest of the DREAM complex functioning as a transcriptional effector of DAF-18/PTEN protein-phosphatase activity resulting in repression of germline gene expression. This work is significant for revealing a network of tumor suppressors that promote survival during cellular and developmental quiescence.

Low molecular weight protein tyrosine phosphatase: A driver of lipid metabolic remodeling in Caenorhabditis elegans

As a member of the class II cysteine-based protein tyrosine phosphatases, low molecular weight protein tyrosine phosphatase (LMWPTP) plays a pivotal role in animal physiology, particularly in signaling transduction, but its specific function in lipid metabolism remains poorly understood. Herein, the structure and metabolic functions of LMWPTP were investigated using the Caenorhabditis elegans (C. elegans) as a convenient model. The nematode LMWPTP was found to be highly conserved in sequence, functional domains, and tertiary structure compared to its mammalian homologs. Through RNA interference (RNAi) targeting lmwptp, we observed a modest increase in lipid accumulation in nematodes, evidenced by higher triglyceride levels, enlarged lipid droplets, and an increase in total fatty acid content, despite no changes in body size. Mechanistically, lmwptp RNAi promoted adipogenesis by modulating the insulin-like growth factor 1 signaling pathway, facilitating the nuclear translocation of DAF-16, which in turn upregulated fat-7 expression. Furthermore, increased ROS levels were associated with enhanced lipogenesis. The knockdown of lmwptp also attenuated lipolysis and lipophagy via modulation of the AMPK pathway. Despite these alterations, key physiological functions related to energy metabolism were preserved, and lifespan was extended with delayed aging markers. These findings highlight LMWPTP's significant role in lipid regulation, offering new insights and potential therapeutic targets for human lipid metabolism disorders.

The Roles of Distinct Transcriptional Factors in the Innate Immunity of C. elegans

Deleterious molecules or factors produced by pathogens can hinder the normal physiological functioning of organisms. In response to these survival challenges, organisms rely on innate immune signaling as their first line of defense, which regulates immune-responsive genes and antimicrobial peptides to protect against pathogenic infections. These genes are under the control of transcription factors, which are known to regulate the transcriptional activity of genes after binding to their regulatory sequences. Previous studies have employed Caenorhabditis elegans as a host-pathogen interaction model to demonstrate the essential role of different transcription factors in the innate immunity of worms. In this review, we summarize the advances made regarding the functioning of distinct transcription factors in the innate immune response upon pathogen infection. Finally, we discuss the open questions in the field, whose resolutions have the potential to expand our understanding of the mechanisms underlying the innate immunity of organisms.

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.

The Role of Hypoxia in Longevity

Aging is marked by a progressive decrease in physiological function and reserve capacity, which results in increased susceptibility to diseases. Understanding the mechanisms of driving aging is crucial for extending health span and promoting human longevity. Hypoxia, marked by reduced oxygen availability, has emerged as a promising area of study within aging research. This review explores recent findings on the potential of oxygen restriction to promote healthy aging and extend lifespan. While the role of hypoxia-inducible factor 1 (HIF-1) in cellular responses to hypoxia is well-established, its impact on lifespan remains complex and context-dependent. Investigations in invertebrate models suggest a role for HIF-1 in longevity, while evidence in mammalian models is limited. Hypoxia extends the lifespan independent of dietary restriction (DR), a known intervention underlying longevity. However, both hypoxia and DR converge on common downstream effectors, such as forkhead box O (FOXO) and flavin-containing monooxygenase (FMOs) to modulate the lifespan. Further work is required to elucidate the molecular mechanisms underlying hypoxia-induced longevity and optimize clinical applications. Understanding the crosstalk between HIF-1 and other longevity-associated pathways is crucial for developing interventions to enhance lifespan and healthspan. Future studies may uncover novel therapeutic strategies to promote healthy aging and longevity in human populations.

Good things come in small packages: The discovery of small RNAs in the smallest animal model

The 2024 Nobel Prize in Physiology or Medicine has been awarded to two pioneering researchers, Victor Ambros and Gary Ruvkun, marking the fourth time research using Caenorhabditis elegans (C. elegans) has received this prestigious recognition. With a rapid life cycle of just 3.5 days and four distinct larval stages, C. elegans serves as an ideal model for exploring complex genetic mechanisms, particularly heterochronic gene regulation. Ambros and Ruvkun's groundbreaking work on lin-4 and lin-14 genes in C. elegans revealed that lin-4 functions as a 22-nucleotide small RNA-now known as a microRNA (miRNA)-that binds complementarily to the 3' UTR of lin-14 mRNA, effectively inhibiting LIN-14 protein synthesis. This discovery was the first demonstration of miRNA in post-transcriptional gene regulation, a finding that has since reshaped our understanding of genetic regulation across species. Their research on small RNAs in C. elegans not only opened a new paradigm in molecular biology but also highlighted the power of this model organism in uncovering universal biological principles.

L-Theanine Extends the Lifespan of Caenorhabditis elegans by Reducing the End Products of Advanced Glycosylation

L-theanine, a non-protein amino acid naturally occurring in tea leaves, is recognized for its antioxidant, anti-inflammatory, and neuroprotective properties. Despite its known benefits, the mechanisms by which L-theanine influences lifespan extension remain poorly understood. This study investigated the effects of L-theanine on the lifespan of Caenorhabditis elegans and explored the underlying mechanisms. Our findings indicate that L-theanine significantly diminishes the accumulation of advanced glycation end products (AGEs), which are biomarkers closely linked to aging and age-related diseases. Through an AGE-level analysis, we observed that L-theanine, when administered during early adulthood, notably extended the lifespan of Caenorhabditis elegans under both normal and high-glucose-induced stress conditions. L-theanine enhanced the lifespan under typical conditions and provided protective effects against high-glucose-induced stress. A further analysis demonstrated that L-theanine extends the lifespan of Caenorhabditis elegans by modulating the DAF-2/DAF-16 insulin-like signaling pathway and reducing the accumulation of advanced glycation end products (AGEs). In summary, this study identified L-theanine as a potential anti-aging intervention that extends the lifespan by reducing AGE accumulation and regulating insulin-like signaling pathways. These findings provide new insights for developing anti-aging strategies and lay the groundwork for further research on the potential benefits of L-theanine in mammals. Future studies could explore the molecular mechanisms, test L-theanine in mammalian models, and assess the long-term side effects.

Aberrant neuronal hyperactivation causes an age-dependent behavioral decline in Caenorhabditis elegans

Age-dependent sensory impairment, memory loss, and cognitive decline are generally attributed to neuron loss, synaptic dysfunction, and decreased neuronal activities over time. Concurrently, increased neuronal activity is reported in humans and other organisms during aging. However, it is unclear whether neuronal hyperactivity is the cause of cognitive impairment or a compensatory mechanism of circuit dysfunction. The roundworm Caenorhabditis elegans exhibits age-dependent declines in an associative learning behavior called thermotaxis, in which its temperature preference on a thermal gradient is contingent on food availability during its cultivation. Cell ablation and calcium imaging demonstrate that the major thermosensory circuit consisting of AFD thermosensory neuron and AIY interneuron is relatively intact in aged animals. On the other hand, ablation of either AWC sensory neurons or AIA interneurons ameliorates the age-dependent thermotaxis decline. Both neurons showed spontaneous and stochastic hyperactivity in aged animals, enhanced by reciprocal communication between AWC and AIA via neurotransmitters and neuropeptides. Our findings suggest that AWC and AIA hyperactivity mediates thermotaxis decline in aged animals. Furthermore, dietary modulation could ameliorate age-dependent thermotaxis decline by suppressing neuronal hyperactivity. We propose that aberrantly enhanced, not diminished, neuronal activities can impair the behavior of aged animals.

Characterizing the Role of daf-16/C. elegans FOXO in Lifespan and Healthspan

In Caenorhabditis elegans (C. elegans), there is a single FOXO transcription factor homolog, encoded by the gene, daf-16. As a central regulator for multiple pathways, DAF-16 integrates these signals to result in changes in longevity, development, fat storage, stress resistance, innate immunity, and reproduction. One of the main advantages of using C. elegans is the ability to study FOXO in the context of the whole animal. Therefore, manipulating the levels or the activity of daf-16 results in visible, scorable phenotypic changes. DAF-16 is the downstream target of the conserved insulin/IGF-1 signaling (IIS) pathway, a PI 3-kinase signaling cascade that ultimately controls its nuclear localization. Since the IIS pathway is a major regulator of lifespan, almost all studies of lifespan modulation examine the requirement of daf-16. More recently, lifespan analysis has been accompanied by healthspan analysis, referring to the time an animal is healthy. In this chapter, I will focus on the assays to assess lifespan and healthspan of C. elegans FOXO/daf-16, in the context of a whole animal.

Predictive models of sarcopenia based on inflammation and pyroptosis-related genes

Background

Sarcopenia is a prevalent condition associated with aging. Inflammation and pyroptosis significantly contribute to sarcopenia.

Methods

Two sarcopenia-related datasets (GSE111016 and GSE167186) were obtained from the Gene Expression Omnibus (GEO), followed by batch effect removal post-merger. The "limma" R package was utilized to identify differentially expressed genes (DEGs). Subsequently, LASSO analysis was conducted on inflammation and pyroptosis-related genes (IPRGs), resulting in the identification of six hub IPRGs. A novel skeletal muscle aging model was developed and validated using an independent dataset. Additionally, Gene Ontology (GO) enrichment analysis was performed on DEGs, along with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and gene set enrichment analysis (GSEA). ssGSEA was employed to assess differences in immune cell proportions between healthy muscle groups in older versus younger adults. The expression levels of the six core IPRGs were quantified via qRT-PCR.

Results

A total of 44 elderly samples and 68 young healthy samples were analyzed for DEGs. Compared to young healthy muscle tissue, T cell infiltration levels in aged muscle tissue were significantly reduced, while mast cell and monocyte infiltration levels were relatively elevated. A new diagnostic screening model for sarcopenia based on the six IPRGs demonstrated high predictive efficiency (AUC = 0.871). qRT-PCR results indicated that the expression trends of these six IPRGs aligned with those observed in the database.

Conclusion

Six biomarkers-BTG2, FOXO3, AQP9, GPC3, CYCS, and SCN1B-were identified alongside a diagnostic model that offers a novel approach for early diagnosis of sarcopenia.

The small GTPase RAB-18 is involved in regulating development/diapause by recruiting the intestinal cholesterol transporter NCR-1 onto the apical side in Caenorhabditis elegans

RAB family proteins, which are small GTPases, are integral to the process of eukaryotic membrane trafficking. In the nematode, Caenorhabditis elegans, 31 RAB proteins have been identified through genome sequencing. Using an RNAi screen specifically targeting C. elegans rab genes, we identified multiple genes that are involved in the regulation of larval development, in particular, the rab-18 gene. Our molecular genetic studies resulted in several findings. First, RAB-18 predominantly functions in the intestine to regulate larval development by modulating steroid hormone signaling. Second, the C. elegans cholesterol transporter NCR-1 is a target of RAB-18 in the intestine. Third, the membrane trafficking of NCR-1 to the apical side in intestinal cells is particularly influenced by RAB-18. Finally, RAB-18 and NCR-1 possibly co-localize on membrane vesicles. Our study is the first to demonstrate the relationship between a RAB protein and a cholesterol transporter, in which the RAB protein probably drives the transporter to the apical membrane in the intestine to regulate cholesterol uptake. This study provides insight into the molecular mechanisms underlying human disease stemming from a transport defect of cholesterol and its derivative.

A non-canonical role of somatic Cyclin D/CYD-1 in oogenesis and in maintenance of reproductive fidelity, dependent on the FOXO/DAF-16 activation state

For the optimal survival of a species, an organism coordinates its reproductive decisions with the nutrient availability of its niche. Thus, nutrient-sensing pathways like insulin-IGF-1 signaling (IIS) play an important role in modulating cell division, oogenesis, and reproductive aging. Lowering of the IIS leads to the activation of the downstream FOXO transcription factor (TF) DAF-16 in Caenorhabditis elegans which promotes oocyte quality and delays reproductive aging. However, less is known about how the IIS axis responds to changes in cell cycle proteins, particularly in the somatic tissues. Here, we show a new aspect of the regulation of the germline by this nutrient-sensing axis. First, we show that the canonical G1-S cyclin, Cyclin D/CYD-1, regulates reproductive fidelity from the uterine tissue of wild-type worms. Then, we show that knocking down cyd-1 in the uterine tissue of an IIS receptor mutant arrests oogenesis at the pachytene stage of meiosis-1 in a DAF-16-dependent manner. We observe activated DAF-16-dependent deterioration of the somatic gonadal tissues like the sheath cells, and transcriptional de-regulation of the sperm-to-oocyte switch genes which may be the underlying reason for the absence of oogenesis. Deleting DAF-16 releases the arrest and leads to restoration of the somatic gonad but poor-quality oocytes are produced. Together, our study reveals the unrecognized cell non-autonomous interaction of Cyclin D/CYD-1 and FOXO/DAF-16 in the regulation of oogenesis and reproductive fidelity.

Sodium Benzoate Induces Fat Accumulation and Reduces Lifespan via the SKN-1/Nrf2 Signaling Pathway: Evidence from the Caenorhabditis elegans Model

BACKGROUND

Sodium benzoate (SB) is widely used in food products, cosmetics, and medical solutions due to its antimicrobial properties. While it is generally considered safe and has potential neuroprotective benefits, SB has also been linked to adverse effects, including hepatic oxidative stress and inflammation. However, the potential effects of SB on obesity and lifespan remain poorly understood.

OBJECTIVES

In this study, we investigated the effects of SB on fat accumulation and lifespan using the nematode Caenorhabditis elegans (C. elegans) as a model system.

METHODS

Wild-type worms were exposed to various SB concentrations (0%, 0.0004%, 0.0008%, 0.004%, and 0.1%) and 0.016% glucose as a positive control for 72 h in liquid or on NGM agar plates.

RESULT

Fat accumulation was assessed through the Oil Red O staining, which revealed that SB induced more fat accumulation compared to vehicle control, even at low concentrations, including the dosage of 0.0004%. Lifespan analysis also demonstrated that SB significantly reduced lifespan in wild-type worms, even at low concentrations. Further investigations found that SKN-1 (an Nrf2 homolog) is necessary for SB-induced fat accumulation and lifespan reduction. Moreover, SB inhibited the nuclear localization of SKN-1 under oxidative stress conditions.

CONCLUSION

These findings suggest that SB may induce fat accumulation and reduce lifespan by inhibiting the oxidative stress-mediated SKN-1 signaling pathway.

ets-10p::gfp expression is predictive of dauer formation in daf-16; daf-7 larvae

In adverse conditions, Caenorhabditis elegans larvae can enter the alternative L2d stage. If conditions remain poor, L2d larvae can molt into stress-resistant dauer larvae. The FOXO ortholog daf-16 promotes dauer formation, but daf-16 mutants can enter dauer with incomplete penetrance in combination with a mutation in daf-7 /TGFβ. The degree to which daf-16 ; daf-7 larvae enter L2d is unknown. Here we show that many daf-16 ; daf-7 mutants express intermediate levels of the ets-10p::gfp L2d marker, suggesting incomplete entry into L2d. Furthermore, lack of ets-10p::gfp expression early in the second larval stage partially predicts which daf-16 ; daf-7 larvae will bypass dauer formation.

Neuropeptide inactivation regulates egg-laying behavior to influence reproductive health in Caenorhabditis elegans

Neural communication requires both fast-acting neurotransmitters and neuromodulators that function on slower timescales to communicate. Endogenous bioactive peptides, often called "neuropeptides," comprise the largest and most diverse class of neuromodulators that mediate crosstalk between the brain and peripheral tissues to regulate physiology and behaviors conserved across the animal kingdom. Neuropeptide signaling can be terminated through receptor binding and internalization or degradation by extracellular enzymes called neuropeptidases. Inactivation by neuropeptidases can shape the dynamics of signaling in vivo by specifying both the duration of signaling and the anatomic path neuropeptides can travel before they are degraded. For most neuropeptides, the identity of the relevant inactivating peptidase(s) is unknown. Here, we established a screening platform in C. elegans utilizing mass spectrometry-based peptidomics to discover neuropeptidases and simultaneously profile the in vivo specificity of these enzymes against each of more than 250 endogenous peptides. We identified NEP-2, a worm ortholog of the mammalian peptidase neprilysin-2, and demonstrated that it regulates specific neuropeptides, including those in the egg-laying circuit. We found that NEP-2 is required in muscle cells to regulate signals from neurons to modulate both behavior and health in the reproductive system. Taken together, our results demonstrate that peptidases, which are an important node of regulation in neuropeptide signaling, affect the dynamics of signaling to impact behavior, physiology, and aging.

Moderate embryonic delay of paternal mitochondrial elimination impairs mating and cognition and alters behaviors of adult animals

Rapid elimination of paternal mitochondria following fertilization is a conserved event in most animals, but its physiological significance remains unclear. We find that modest delay of paternal mitochondrial elimination (PME) in Caenorhabditis elegans embryos unexpectedly impairs mating and cognition of adult animals and alters their locomotion behaviors. Delayed PME causes decreased adenosine triphosphate (ATP) levels in early embryos, which lead to impaired physiological functions of adult animals through an energy-sensing pathway mediated by an adenosine monophosphate (AMP)-activated protein kinase, AAK-2, and a forkhead box class O (FOXO) transcription factor, DAF-16. Treatment of PME-delayed animals with MK-4, a subtype of vitamin K2 that can improve mitochondrial ATP production, restores ATP levels in early embryos, and rescues physiological defects of adult animals. Our results suggest that moderate PME delay during embryo development adversely affects crucial physiological functions in adults, which could be evolutionarily disadvantageous. These observations provide mechanistic explanations for the need to swiftly remove paternal mitochondria early during embryo development.

The C. elegans Myc-family of transcription factors coordinate a dynamic adaptive response to dietary restriction

Dietary restriction (DR), the process of decreasing overall food consumption over an extended period of time, has been shown to increase longevity across evolutionarily diverse species and delay the onset of age-associated diseases in humans. In Caenorhabditis elegans, the Myc-family transcription factors (TFs) MXL-2 (Mlx) and MML-1 (MondoA/ChREBP), which function as obligate heterodimers, and PHA-4 (orthologous to FOXA) are both necessary for the full physiological benefits of DR. However, the adaptive transcriptional response to DR and the role of MML-1::MXL-2 and PHA-4 remains elusive. We identified the transcriptional signature of C. elegans DR, using the eat-2 genetic model, and demonstrate broad changes in metabolic gene expression in eat-2 DR animals, which requires both mxl-2 and pha-4. While the requirement for these factors in DR gene expression overlaps, we found many of the DR genes exhibit an opposing change in relative gene expression in eat-2;mxl-2 animals compared to wild-type, which was not observed in eat-2 animals with pha-4 loss. Surprisingly, we discovered more than 2000 genes synthetically dysregulated in eat-2;mxl-2, out of which the promoters of down-regulated genes were substantially enriched for PQM-1 and ELT-1/3 GATA TF binding motifs. We further show functional deficiencies of the mxl-2 loss in DR outside of lifespan, as eat-2;mxl-2 animals exhibit substantially smaller brood sizes and lay a proportion of dead eggs, indicating that MML-1::MXL-2 has a role in maintaining the balance between resource allocation to the soma and to reproduction under conditions of chronic food scarcity. While eat-2 animals do not show a significantly different metabolic rate compared to wild-type, we also find that loss of mxl-2 in DR does not affect the rate of oxygen consumption in young animals. The gene expression signature of eat-2 mutant animals is consistent with optimization of energy utilization and resource allocation, rather than induction of canonical gene expression changes associated with acute metabolic stress, such as induction of autophagy after TORC1 inhibition. Consistently, eat-2 animals are not substantially resistant to stress, providing further support to the idea that chronic DR may benefit healthspan and lifespan through efficient use of limited resources rather than broad upregulation of stress responses, and also indicates that MML-1::MXL-2 and PHA-4 may have distinct roles in promotion of benefits in response to different pro-longevity stimuli.

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.

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.

Understanding Longevity: SIN-3 and DAF-16 Revealed as Independent Players in Lifespan Regulation

Aging is the process of gradual physio-biochemical deterioration. Although aging is inevitable, healthy aging is the key to individual and communal well-being. Therefore, it is essential to understand the regulation of aging. SIN-3/Sin-3 is a unique regulatory protein that regulates aging without DNA-binding activity. It functions by establishing multiple protein interactions. To understand the functional mechanism of this transcriptional regulator, the Caenorhabditis elegans protein interactome was assessed for SIN-3 interactions. DAF-16/FOXO emerged as one of the leading contenders for SIN-3-mediated regulation of aging. This study looks at the concerted role of SIN-3 and DAF-16 proteins in lifespan regulation. Phenotypic profiling for the mutants of these genes shows the functional accord between these 2 proteins with similar functions in stress response and vital biological processes. However, there were no significant physical interactions when checked for protein-protein interaction between SIN-3 and DAF-16 proteins. C. elegans genomics and transcriptomics data also indicated the possibilities of concerted gene regulation. This genetic regulation is more likely related to SIN-3 dominance on DAF-16 function. Overall, SIN-3 and DAF-16 proteins have strong functional interactions that ensure healthy aging. The influence of SIN-3 on DAF-16-mediated stress response is one of their convergence points in longevity regulation.

Exposure to 6-PPD quinone disrupts glucose metabolism associated with lifespan reduction by affecting insulin and AMPK signals in Caenorhabditis elegans

Glucose metabolism plays an important role for formation of normal physiological state of organisms. However, association between altered glucose metabolism and toxicity of 6-PPD quinone (6-PPDQ) remains largely unknown. In 1-100 μg/L 6-PPDQ exposed Caenorhabditis elegans, we observed increased glucose content. After 6-PPDQ exposure (1-100 μg/L), expressions of F47B8.10 and fbp-1 governing gluconeogenesis were increased, and expressions of hxk-1, hxk-3, pfk-1.1, pyk-1, and pyk-2 governing glycolysis were decreased. Under 6-PPDQ exposure condition, glucose content could be changed by RNAi of F47B8.10, hxk-1, and hxk-3, key genes for gluconeogenesis and glycolysis. In 6-PPDQ exposed nematodes, RNAi of daf-16 and aak-2 elevated glucose content, increased expressions of F47B8.10 and/or fbp-1, and decreased expressions of hxk-1, hxk-3, and/or pfk-1.1. Additionally, lifespan and locomotion during aging were increased by RNAi of F47B8.10 and decreased by RNAi of hxk-1 and hxk-3 in 6-PPDQ exposed nematodes. Moreover, after 6-PPDQ exposure, RNAi of F47B8.10 decreased expressions of insulin peptide genes (ins-7 and daf-28) and insulin receptor gene daf-2 and increased expressions of daf-16 and aak-2. In 6-PPDQ exposed nematodes, RNAi of hxk-1 and hxk-3 further increased expressions of ins-7, daf-28, and daf-2 and decreased expressions of daf-16 and aak-2. Our results demonstrated important association between altered glucose metabolism and toxicity of 6-PPDQ in inducing lifespan reduction in organisms.

Exploring the Relationship of rs2802292 with Diabetes and NAFLD in a Southern Italian Cohort-Nutrihep Study

Background: The minor G-allele of FOXO3 rs2802292 is associated with human longevity. The aim of this study was to test the protective effect of the variant against the association with type 2 Diabetes and NAFLD. Methods: rs2802292 was genotyped in a large population of middle-aged subjects (n = 650) from a small city in Southern Italy. All participants were interviewed to collect information about lifestyle and dietary habits; clinical characteristics were recorded, and blood samples were collected from all subjects. The association between rs2802292 and NAFLD or diabetes was tested using a logistic model and mediation analysis adjusted for covariates. Results: Overall, the results indicated a statistical association between diabetes and rs2802292, especially for the TT genotype (OR = 2.14, 1.01 to 4.53 95% C.I., p = 0.05) or in any case for those who possess the G-allele (OR = 0.45, 0.25 to 0.81 95% C.I., p = 0.008). Furthermore, we found a mediation effect of rs2802292 on diabetes (as mediator) and NAFLD. There is no direct relationship between rs2802292 and NAFLD, but the effect is direct (β = 0.10, -0.003 to 0.12 95% C.I., p = 0.04) on diabetes, but only in TT genotypes. Conclusions: The data on our cohort indicate that the longevity-associated FOXO3 variant may have protective effects against diabetes and NAFLD.

Nucleolar stress induces nucleolar stress body formation via the NOSR-1/NUMR-1 axis in Caenorhabditis elegans

Environmental stimuli not only alter gene expression profiles but also induce structural changes in cells. How distinct nuclear bodies respond to cellular stress is poorly understood. Here, we identify a subnuclear organelle named the nucleolar stress body (NoSB), the formation of which is induced by the inhibition of rRNA transcription or inactivation of rRNA processing and maturation in C. elegans. NoSB does not colocalize with other previously described subnuclear organelles. We conduct forward genetic screening and identify a bZIP transcription factor, named nucleolar stress response-1 (NOSR-1), that is required for NoSB formation. The inhibition of rRNA transcription or inactivation of rRNA processing and maturation increases nosr-1 expression. By using transcriptome analysis of wild-type animals subjected to different nucleolar stress conditions and nosr-1 mutants, we identify that the SR-like protein NUMR-1 (nuclear localized metal responsive) is the target of NOSR-1. Interestingly, NUMR-1 is a component of NoSB and itself per se is required for the formation of NoSB. We conclude that the NOSR-1/NUMR-1 axis likely responds to nucleolar stress and mediates downstream stress-responsive transcription programs and subnuclear morphology alterations in C. elegans.

Forkhead box O1 transcription factor; a therapeutic target for diabetic cardiomyopathy

Cardiovascular disease including diabetic cardiomyopathy (DbCM) represents the leading cause of death in people with diabetes. DbCM is defined as ventricular dysfunction in the absence of underlying vascular diseases and/or hypertension. The known molecular mediators of DbCM are multifactorial, including but not limited to insulin resistance, altered energy metabolism, lipotoxicity, endothelial dysfunction, oxidative stress, apoptosis, and autophagy. FoxO1, a prominent member of forkhead box O transcription factors, is involved in regulating various cellular processes in different tissues. Altered FoxO1 expression and activity have been associated with cardiovascular diseases in diabetic subjects. Herein we provide an overview of the role of FoxO1 in various molecular mediators related to DbCM, such as altered energy metabolism, lipotoxicity, oxidative stress, and cell death. Furthermore, we provide valuable insights into its therapeutic potential by targeting these perturbations to alleviate cardiomyopathy in settings of type 1 and type 2 diabetes.

Integrated analysis of miRNAome and transcriptome reveals that microgravity induces the alterations of critical functional gene modules via the regulation of miRNAs in short-term space-flown C. elegans

Microgravity, as a unique hazardous factor encountered in space, can induce a series of harmful effects on living organisms. The impact of microgravity on the pivotal functional gene modules stemming from gene enrichment analysis via the regulation of miRNAs is not fully illustrated. To explore the microgravity-induced alterations in critical functional gene modules via the regulation of miRNAs, in the present study, we proposed a novel bioinformatics algorithm for the integrated analysis of miRNAome and transcriptome from short-term space-flown C. elegans. The samples of C. elegans were exposed to two space conditions, namely spaceflight (SF) and spaceflight control (SC) onboard the International Space Station for 4 days. Additionally, the samples of ground control (GC) were included for comparative analysis. Using the present algorithm, we constructed regulatory networks of functional gene modules annotated from differentially expressed genes (DEGs) and their associated regulatory differentially expressed miRNAs (DEmiRNAs). The results showed that functional gene modules of molting cycle, defense response, fatty acid metabolism, lysosome, and longevity regulating pathway were facilitated by 25 down-regulated DEmiRNAs (e.g., cel-miR-792, cel-miR-65, cel-miR-70, cel-lsy-6, cel-miR-796, etc.) in the SC vs. GC groups, whereas these modules were inhibited by 13 up-regulated DEmiRNAs (e.g., cel-miR-74, cel-miR-229, cel-miR-70, cel-miR-249, cel-miR-85, etc.) in the SF vs. GC groups. These findings indicated that microgravity could significantly alter gene expression patterns and their associated functional gene modules in short-term space-flown C. elegans. Additionally, we identified 34 miRNAs as post-transcriptional regulators that modulated these functional gene modules under microgravity conditions. Through the experimental verification, our results demonstrated that microgravity could induce the down-regulation of five critical functional gene modules (i.e., molting cycle, defense response, fatty acid metabolism, lysosome, and longevity regulating pathways) via the regulation of miRNAs in short-term space-flown C. elegans.

SPP-5 affects larval arrest via insulin signaling pathway in Caenorhabditis elegans

Diapause is an endocrine-mediated metabolic and growth arrest state in response to unfavorable external environments. The nematode Caenorhabditis elegans can enter diapause/arrest during embryonic, larval, or adult stages when subjected to detrimental external environments. Larval stage 1 (L1) arrest happens when animals hatch without food. Previous work has shown that the insulin pathway plays a prominent role in regulating L1 arrest. However, the downstream signal molecular mechanisms and biomarkers are still missing. In this study, we showed that SaPosin-like Protein family member SPP-5 is significantly upregulated during L1 arrest, suggesting that it could act as an L1 arrest biomarker. Using RNA interference we demonstrated that spp-5  knockdown accelerated larval development, while the overexpression resulted in L1 arrest. Consistently, SPP-5 level was significantly up-regulated in the L1 arrest daf-2(e1370) mutants, and spp-5(RNAi) suppressed the daf-2(e1370) induced L1 arrest. These results suggest that SPP-5 can serve as an L1 arrest biomarker and promote the arrest probably via the insulin signaling pathway.

Novel insights into regulators and functional modulators of adipogenesis

Adipogenesis is a process that differentiates new adipocytes from precursor cells and is tightly regulated by several factors, including many transcription factors and various post-translational modifications. Recently, new roles of adipogenesis have been suggested in various diseases. However, the molecular mechanisms and functional modulation of these adipogenic genes remain poorly understood. This review summarizes the regulatory factors and modulators of adipogenesis and discusses future research directions to identify novel mechanisms regulating adipogenesis and the effects of adipogenic regulators in pathological conditions. The master adipogenic transcriptional factors PPARγ and C/EBPα were identified along with other crucial regulatory factors such as SREBP, Kroxs, STAT5, Wnt, FOXO1, SWI/SNF, KLFs, and PARPs. These transcriptional factors regulate adipogenesis through specific mechanisms, depending on the adipogenic stage. However, further studies related to the in vivo role of newly discovered adipogenic regulators and their function in various diseases are needed to develop new potent therapeutic strategies for metabolic diseases and cancer.

Poplar Bud (Populus) Extraction and Chinese Propolis Counteract Oxidative Stress in Caenorhabditis elegans via Insulin/IGF-1 Signaling Pathway

Poplar buds are characterized by a high content of phenolic compounds, which exhibit a broad spectrum of biological activities. However, the relationship between Chinese propolis and poplar buds based on their antioxidant capacities and underlying mechanisms remains unclear. This study aimed to investigate the antioxidant properties of poplar bud (Populus) extract (PBE) and Chinese propolis (CP) and to elucidate the mechanisms behind their activity. High-performance liquid chromatography (HPLC) analysis revealed that both PBE and CP contain a significant amount of phenolic acids and flavonoids. 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric-reducing antioxidant power (FRAP) assays demonstrated that PBE and CP possess excellent antioxidant activity. Furthermore, administration of PBE and CP improved the survival rate of C. elegans under oxidative stress. They also decreased the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), while enhancing the activity of antioxidant enzymes (SOD, CAT). PBE and CP intervention upregulated the expression of key genes daf-16, sod-3, hsp-16.2, and skn-1 in nematodes. This suggests that the antioxidant activity of PBE and CP is dependent on daf-16 and skn-1 signaling pathways. In conclusion, poplar bud extracts ha have the potential to become a substitute for propolis and a potential therapeutic agent for treating diseases associated with oxidative damage.

Uncovering the Molecular Pathways Implicated in the Anti-Cancer Activity of the Imidazoquinoxaline Derivative EAPB02303 Using a Caenorhabditis elegans Model

Imiqualines are analogues of the immunomodulatory drug imiquimod. EAPB02303, the lead of the second-generation imiqualines, is characterized by significant anti-tumor effects with IC50s in the nanomolar range. We used Caenorhabditis elegans transgenic and mutant strains of two key signaling pathways (PI3K-Akt and Ras-MAPK) disrupted in human cancers to investigate the mode of action of EAPB02303. The ability of this imiqualine to inhibit the insulin/IGF1 signaling (IIS) pathway via the PI3K-Akt kinase cascade was explored through assessing the lifespan of wild-type worms. Micromolar doses of EAPB02303 significantly enhanced longevity of N2 strain and led to the nuclear translocation and subsequent activation of transcription factor DAF-16, the only forkhead box transcription factor class O (Fox O) homolog in C. elegans. Moreover, EAPB02303 significantly reduced the multivulva phenotype in let-60/Ras mutant strains MT2124 and MT4698, indicative of its mode of action through the Ras pathway. In summary, we showed that EAPB02303 potently reduced the activity of IIS and Ras-MAPK signaling in C. elegans. Our results revealed the mechanism of action of EAPB02303 against human cancers associated with hyperactivated IIS pathway and oncogenic Ras mutations.

Combinatorial transcriptomic and genetic dissection of insulin/IGF-1 signaling-regulated longevity in Caenorhabditis elegans

Classical genetic analysis is invaluable for understanding the genetic interactions underlying specific phenotypes, but requires laborious and subjective experiments to characterize polygenic and quantitative traits. Contrarily, transcriptomic analysis enables the simultaneous and objective identification of multiple genes whose expression changes are associated with specific phenotypes. Here, we conducted transcriptomic analysis of genes crucial for longevity using datasets with daf-2/insulin/IGF-1 receptor mutant Caenorhabditis elegans. Our analysis unraveled multiple epistatic relationships at the transcriptomic level, in addition to verifying genetically established interactions. Our combinatorial analysis also revealed transcriptomic changes associated with longevity conferred by daf-2 mutations. In particular, we demonstrated that the extent of lifespan changes caused by various mutant alleles of the longevity transcription factor daf-16/FOXO matched their effects on transcriptomic changes in daf-2 mutants. We identified specific aging-regulating signaling pathways and subsets of structural and functional RNA elements altered by different genes in daf-2 mutants. Lastly, we elucidated the functional cooperation between several longevity regulators, based on the combination of transcriptomic and molecular genetic analysis. These data suggest that different biological processes coordinately exert their effects on longevity in biological networks. Together our work demonstrates the utility of transcriptomic dissection analysis for identifying important genetic interactions for physiological processes, including aging and longevity.

Evolution of diapause in the African turquoise killifish by remodeling the ancient gene regulatory landscape

Suspended animation states allow organisms to survive extreme environments. The African turquoise killifish has evolved diapause as a form of suspended development to survive a complete drought. However, the mechanisms underlying the evolution of extreme survival states are unknown. To understand diapause evolution, we performed integrative multi-omics (gene expression, chromatin accessibility, and lipidomics) in the embryos of multiple killifish species. We find that diapause evolved by a recent remodeling of regulatory elements at very ancient gene duplicates (paralogs) present in all vertebrates. CRISPR-Cas9-based perturbations identify the transcription factors REST/NRSF and FOXOs as critical for the diapause gene expression program, including genes involved in lipid metabolism. Indeed, diapause shows a distinct lipid profile, with an increase in triglycerides with very-long-chain fatty acids. Our work suggests a mechanism for the evolution of complex adaptations and offers strategies to promote long-term survival by activating suspended animation programs in other species.

Jujubae Fructus extract prolongs lifespan and improves stress tolerance in Caenorhabditis elegans dependent on DAF-16/SOD-3

Jujubae Fructus, the fruit of Ziziphus jujuba Mill has been used as one of the medicine food homology species for thousands of years in China. Studies have shown that the active ingredients of Jujubae Fructus have a variety of biological effects, but its role in the aging process still lacks knowledge. Here, we investigated the effect of Jujubae Fructus extract (JE) on Caenorhabditis elegans lifespan and its potential mechanism. The lifespan of C. elegans treated with JE was signifificantly increased in a dose-dependent manner. In addition, JE treatment prolonged the reproductive period and increased normal activity during aging in C. elegans. Similarly, JE supplementation also enhanced the resistance to heat and oxidative stress in C. elegans. Furthermore, the mutant worms' lifespan assays demonstrated that JE requires daf-16 to prolong lifespan. DAF-16::GFP analysis of TJ356 showed that JE treatment translocates DAF-16::GFP to nucleus in transgenic worms. By analyzing the downstream of daf-16, we identify that JE may regulate sod3 downstream of daf-16. Mutant worms' lifespan and transgenic reporter gene expression assays revealed that increasing SOD-3 expression was critical for extending longevity in C. elegans with JE therapy. Collectively, these data indicate that JE may have an important role in C. elegans longevity that is dependent on DAF-16 and SOD-3.

C16ORF70/MYTHO promotes healthy aging in C.elegans and prevents cellular senescence in mammals

The identification of genes that confer either extension of life span or accelerate age-related decline was a step forward in understanding the mechanisms of aging and revealed that it is partially controlled by genetics and transcriptional programs. Here, we discovered that the human DNA sequence C16ORF70 encodes a protein, named MYTHO (macroautophagy and youth optimizer), which controls life span and health span. MYTHO protein is conserved from Caenorhabditis elegans to humans and its mRNA was upregulated in aged mice and elderly people. Deletion of the orthologous myt-1 gene in C. elegans dramatically shortened life span and decreased animal survival upon exposure to oxidative stress. Mechanistically, MYTHO is required for autophagy likely because it acts as a scaffold that binds WIPI2 and BCAS3 to recruit and assemble the conjugation system at the phagophore, the nascent autophagosome. We conclude that MYTHO is a transcriptionally regulated initiator of autophagy that is central in promoting stress resistance and healthy aging.

The 18S rRNA Methyltransferase DIMT-1 Regulates Lifespan in the Germline Later in Life

Ribosome heterogeneity has emerged as an important regulatory control feature for determining which proteins are synthesized, however, the influence of age on ribosome heterogeneity is not fully understood. Whether mRNA transcripts are selectively translated in young versus old cells and whether dysregulation of this process drives organismal aging is unknown. Here we examined the role of ribosomal RNA (rRNA) methylation in maintaining appropriate translation as organisms age. In a directed RNAi screen, we identified the 18S rRNA N6'-dimethyl adenosine (m6,2A) methyltransferase, dimt-1, as a regulator of C. elegans lifespan and stress resistance. Lifespan extension induced by dimt-1 deficiency required a functional germline and was dependent on the known regulator of protein translation, the Rag GTPase, raga-1, which links amino acid sensing to the mechanistic target of rapamycin complex (mTORC)1. Using an auxin-inducible degron tagged version of dimt-1, we demonstrate that DIMT-1 functions in the germline after mid-life to regulate lifespan. We further found that knock-down of dimt-1 leads to selective translation of transcripts important for stress resistance and lifespan regulation in the C. elegans germline in mid-life including the cytochrome P450 daf-9, which synthesizes a steroid that signals from the germline to the soma to regulate lifespan. We found that dimt-1 induced lifespan extension was dependent on the daf-9 signaling pathway. This finding reveals a new layer of proteome dysfunction, beyond protein synthesis and degradation, as an important regulator of aging. Our findings highlight a new role for ribosome heterogeneity, and specific rRNA modifications, in maintaining appropriate translation later in life to promote healthy aging.

Knockdown of neuronal DAF-15/Raptor promotes healthy aging in C. elegans

The highly conserved target of rapamycin (TOR) pathway plays an important role in aging across species. Previous studies have established that inhibition of the TOR complex 1 (TORC1) significantly extends lifespan in Caenorhabditiselegans. However, it has not been clear whether TORC1 perturbation affects aging in a spatiotemporal manner. Here, we apply the auxin-inducible degradation tool to knock down endogenous DAF-15, the C. elegans ortholog of regulatory associated protein of TOR (Raptor), to characterize its roles in aging. Global or tissue-specific inhibition of DAF-15 during development results in various growth defects, whereas neuron-specific knockdown of DAF-15 during adulthood significantly extends lifespan and healthspan. The neuronal DAF-15 deficiency-induced longevity requires the intestinal activities of DAF-16/FOXO and PHA-4/FOXA transcription factors, as well as the AAK-2/AMP-activated protein kinase α catalytic subunit. Transcriptome profiling reveals that the neuronal DAF-15 knockdown promotes the expression of genes involved in protection. These findings define the tissue-specific roles of TORC1 in healthy aging and highlight the importance of neuronal modulation of aging.

Nematode Uptake Preference toward Different Nanoplastics through Avoidance Behavior Regulation

Expounding bioaccumulation pathways of nanoplastics in organisms is a prerequisite for assessing their ecological risks in the context of global plastic pollution. Invertebrate uptake preference toward nanoplastics is a key initial step of nanoplastic food chain transport that controls their global biosafety, while the biological regulatory mechanism remains unclear. Here, we reveal a preferential uptake mechanism involving active avoidance of nanoplastics by Caenorhabditis elegans and demonstrate the relationship between the uptake preference and nanoplastic characteristics. Nanoplastics with 100 nm in size or positive surface charges induce stronger avoidance due to higher toxicity, causing lower accumulation in nematodes, compared to the 500 nm-sized or negatively charged nanoplastics, respectively. Further evidence showed that nematodes did not actively ingest any types of nanoplastics, while different nanoplastics induced defense responses in a toxicity-dependent manner and distinctly stimulated the avoidance behavior of nematodes (ranged from 15.8 to 68.7%). Transcriptomics and validations using mutants confirmed that the insulin/IGF signaling (IIS) pathway is essential for the selective avoidance of nanoplastics. Specifically, the activation of DAF-16 promoted the IIS pathway-mediated defense against nanoplastics and stimulated the avoidance behavior, increasing the survival chances of nematodes. Considering the genetical universality of this defense response among invertebrates, such an uptake preference toward certain nanoplastics could lead to cascaded risks in the ecosystem.

Cell non-autonomous control of autophagy and metabolism by glial cells

Glia are the protectors of the nervous system, providing neurons with support and protection from cytotoxic insults. We previously discovered that four astrocyte-like glia can regulate organismal proteostasis and longevity in C. elegans. Expression of the UPRER transcription factor, XBP-1s, in these glia increases stress resistance, and longevity, and activates the UPRER in intestinal cells via neuropeptides. Autophagy, a key regulator of metabolism and aging, has been described as a cell autonomous process. Surprisingly, we find that glial XBP-1s enhances proteostasis and longevity by cell non-autonomously reprogramming organismal lipid metabolism and activating autophagy. Glial XBP-1s regulates the activation of another transcription factor, HLH-30/TFEB, in the intestine. HLH-30 activates intestinal autophagy, increases intestinal lipid catabolism, and upregulates a robust transcriptional program. Our study reveals a novel role for glia in regulating peripheral lipid metabolism, autophagy, and organellar health through peripheral activation of HLH-30 and autophagy.

Queen bee gut microbiota extends honeybee lifespan by inhibiting insulin signaling

Queen and worker bees are natural models for aging research, as their lifespans vary considerably independent of genetic variation. Investigating the reasons why queens live longer than workers is of great significance for research on the universal processes of aging in animals. The gut microbiome has received attention as a vital regulator of host health, while its precise role in honeybee aging needs further investigation. The effects and mechanisms behind the relationship between gut microbiota and worker lifespan were measured by transplanting queen bee gut bacteria (QG) and worker bee gut bacteria (WG) into microbiota-free (MF) workers. The transplantation of QG to MF bees significantly extended the workers' lifespans compared with MF and WG bees. Untargeted metabolomics identified 49 lifespan-related differential metabolites, and Kyoto Encyclopedia of Genes and Genomes analysis of these revealed three lifespan-related metabolic pathways: insulin/insulin-like growth factor signaling, immune, and ketone body metabolism pathways. Further verification showed that QG inhibited the expression of insulin-like peptides (ILPs), and the expression of ILPs was lower in natural queens than in natural workers. QG transplantation also stimulated the expression of antioxidant genes and lowered oxidative damage products in natural queen bees. However, gut microbiota transplantation failed to mimic the immune properties and ketone body metabolism profiles of natural queens and workers. Concisely, QG could increase the antioxidant capacity to extend lifespan by inhibiting insulin signaling. These findings may help determine the mechanisms behind queen longevity and provide further insights into the role of gut symbionts.

IMPORTANCE

Queen and worker bees share the same genetic background but have vastly different lifespans. The gut microbiome regulates host health, suggesting that differences in lifespan between queen and worker bees could be related to gut bacteria. Herein, we used an innovative method to transplant gut microbiota from adult queen or worker bees to microbiota-free bees. The transplantation of queen gut microbiota to microbiota-free bees extended their lifespan. Insulin/insulin-like growth factor signaling, a highly conserved metabolic pathway related to lifespan, displayed identical expression profiles in natural queen bees and microbiota-free bees transplanted with queen microbiota. This finding significantly expands our understanding of the relationships between intestinal bacteria, host health, and the biology of aging.

Polyphenol-rich fermented hempseed ethanol extracts improve obesity, oxidative stress, and neural health in high-glucose diet-induced Caenorhabditis elegans

Whole hempseed (WHS), fermented whole hempseed (FWHS), dehulled hempseed (DHS), and fermented dehulled hempseed (FDHS) ethanol extracts were tested for their toxicity and physiological benefits in relation to their phenolic profiles. The safety of all samples was confirmed by the absence of toxic effects on HepG2 cells. FWHS exhibited the highest capacity to inhibit lipase activity (70.80%) and acetylcholinesterase (AChE) (78.94%) in vitro. Similarly, in HepG2 cells, FWHS revealed the greatest ability to reduce the accumulation of reactive oxygen species (ROS). Fermented hempseed demonstrated superior antioxidant, neuroprotective and anti-fat potential, counteracting ageing in high glucose diet-induced C. elegans than unfermented. HPLC and UHPLC-Q-TOF-MS/MS2 phenolic identification revealed the presence of diverse flavonoids, phenolic acids, lignanamides, and phenylamides in hempseed extracts. Among these polyphenols, quercetin, gallic acid, and kaempferol exhibited excellent antioxidant potential, whereas N-trans-feruloyl tyramine displayed the highest anti-lipase potential. This study suggests that polyphenol-rich hempseed exhibits potent antioxidant, and anti-obesity effects, and could improve neural health.

LPD-3 as a megaprotein brake for aging and insulin-mTOR signaling in C. elegans

Insulin-mechanistic target of rapamycin (mTOR) signaling drives anabolic growth during organismal development; its late-life dysregulation contributes to aging and limits lifespans. Age-related regulatory mechanisms and functional consequences of insulin-mTOR remain incompletely understood. Here, we identify LPD-3 as a megaprotein that orchestrates the tempo of insulin-mTOR signaling during C. elegans aging. We find that an agonist insulin, INS-7, is drastically overproduced from early life and shortens lifespan in lpd-3 mutants. LPD-3 forms a bridge-like tunnel megaprotein to facilitate non-vesicular cellular lipid trafficking. Lipidomic profiling reveals increased hexaceramide species in lpd-3 mutants, accompanied by up-regulation of hexaceramide biosynthetic enzymes, including HYL-1. Reducing the abundance of HYL-1, insulin receptor/DAF-2 or mTOR/LET-363, normalizes INS-7 levels and rescues the lifespan of lpd-3 mutants. LPD-3 antagonizes SINH-1, a key mTORC2 component, and decreases expression with age. We propose that LPD-3 acts as a megaprotein brake for organismal aging and that its age-dependent decline restricts lifespan through the sphingolipid-hexaceramide and insulin-mTOR pathways.

Bacterial vitamin B6 is required for post-embryonic development in C. elegans

Nutritional intake influences animal growth, reproductive capacity, and survival of animals. Under nutrition deficiency, animal developmental arrest occurs as an adaptive strategy to survive. However, the nutritional basis and the underlying nutrient sensing mechanism essential for animal regrowth after developmental arrest remain to be explored. In Caenorhabditis elegans, larvae undergo early developmental arrest are stress resistant, and they require certain nutrients to recover postembryonic development. Here, we investigated the developmental arrest in C. elegans feeding on Lactiplantibacillus plantarum, and the rescue of the diapause state with trace supplementation of Escherichia coli. We performed a genome-wide screen using 3983 individual gene deletion E. coli mutants and identified E. coli genes that are indispensable for C. elegans larval growth on originally not nutritionally sufficient bacteria L. plantarum. Among these crucial genes, we confirmed E. coli pdxH, and the downstream metabolite pyridoxal 5-P (PLP, Vitamin B6) as important nutritional factors for C. elegans postembryonic development. Transcriptome results suggest that bacterial pdxH affects host development by coordinating host metabolic processes and PLP binding. Additionally, the developmental arrest induced by the L. plantarum diet in worm does not depend on the activation of FoxO/DAF-16. Altogether, these results highlight the role of microbial metabolite PLP as a crucial cofactor to restore postembryonic development in C. elegans.

Forkhead box O proteins: steering the course of stem cell fate

Stem cells are pivotal players in the intricate dance of embryonic development, tissue maintenance, and regeneration. Their behavior is delicately balanced between maintaining their pluripotency and differentiating as needed. Disruptions in this balance can lead to a spectrum of diseases, underscoring the importance of unraveling the complex molecular mechanisms that govern stem cell fate. Forkhead box O (FOXO) proteins, a family of transcription factors, are at the heart of this intricate regulation, influencing a myriad of cellular processes such as survival, metabolism, and DNA repair. Their multifaceted role in steering the destiny of stem cells is evident, as they wield influence over self-renewal, quiescence, and lineage-specific differentiation in both embryonic and adult stem cells. This review delves into the structural and regulatory intricacies of FOXO transcription factors, shedding light on their pivotal roles in shaping the fate of stem cells. By providing insights into the specific functions of FOXO in determining stem cell fate, this review aims to pave the way for targeted interventions that could modulate stem cell behavior and potentially revolutionize the treatment and prevention of diseases.

Dietary E. coli promotes age-dependent chemotaxis decline in C. elegans

An animal's ability to sense odors declines during aging, and its olfactory drive is tuned by internal states such as satiety. However, whether internal states modulate an age-dependent decline in odor sensation is unknown. To address this issue, we utilized the nematode Caenorhabditis elegans and compared their chemotaxis abilities toward attractive odorants when aged under different dietary conditions. Feeding with the standard laboratory diet, Escherichia coli attenuated the chemotaxis ability toward diacetyl, isoamyl alcohol, and benzaldehyde when aged. On the other hand, feeding with either the lactic acid bacteria Lactobacillus reuteri or food deprivation selectively maintained the chemotaxis ability toward diacetyl. Our results suggest that ingestion of E. coli causes age-dependent chemotaxis decline. The changes in the chemotaxis behavior are attributed to the different expressions of diacetyl receptor odr-10, and the chemotaxis behavior of aged animals under food deprivation is shown to be dependent on daf-16. Our study demonstrates the molecular mechanism of how diet shapes the trajectory of age-dependent decline in chemosensory behaviors.

Mercuric sulfide nanoparticles suppress the neurobehavioral functions of Caenorhabditis elegans through a Skp1-dependent mechanism

Cinnabar is the naturally occurring mercuric sulfide (HgS) and concerns about its safety have been grown. However, the molecular mechanism of HgS-related neurotoxicity remains unclear. S-phase kinase-associated protein 1 (Skp1), identified as the target protein of HgS, plays a crucial role in the development of neurological diseases. This study aims to investigate the neurotoxic effects and molecular mechanism of HgS based on Skp1 using the Caenorhabditis elegans (C. elegans) model. We prepared the HgS nanoparticles and conducted a comparative analysis of neurobehavioral differences in both wild-type C. elegans (N2) and a transgenic strain of C. elegans (VC1241) with a knockout of the SKP1 homologous gene after exposure to HgS nanoparticles. Our results showed that HgS nanoparticles could suppress locomotion, defecation, egg-laying, and associative learning behaviors in N2 C. elegans, while no significant alterations were observed in the VC1241 C. elegans. Furthermore, we conducted a 4D label-free proteomics analysis and screened 504 key proteins significantly affected by HgS nanoparticles through Skp1. These proteins play pivotal roles in various pathways, including SNARE interactions in vesicular transport, TGF-beta signaling pathway, calcium signaling pathway, FoxO signaling pathway, etc. In summary, HgS nanoparticles at high doses suppress the neurobehavioral functions of C. elegans through a Skp1-dependent mechanism.

Antiaging Strategies and Remedies: A Landscape of Research Progress and Promise

Aging is typified by a gradual loss of physiological fitness and accumulation of cellular damage, leading to deteriorated functions and enhanced vulnerability to diseases. Antiaging research has a long history throughout civilization, with many efforts put forth to understand and prevent the effects of aging. Multiple strategies aiming to promote healthy aging and extend the lifespan have been developed including lifestyle adjustments, medical treatments, and social programs. A multitude of antiaging medicines and remedies have also been explored. Here, we use data from the CAS Content Collection to analyze the publication landscape of recent research related to antiaging strategies and treatments. We review the recent advances and delineate trends in research headway of antiaging knowledge and practice across time, geography, and development pipelines. We further assess the state-of-the-art antiaging approaches and explore their correlations with age-related diseases. The landscape of antiaging drugs has been outlined and explored. Well-recognized and novel, currently evaluated antiaging agents have also been summarized. Finally, we review clinical applications of antiaging products with their development pipelines. The objective of this review is to summarize current knowledge on preventive strategies and treatment remedies in the field of aging, to outline challenges and evaluate growth opportunities, in order to further efforts to solve the problems that remain.

The ACE inhibitor captopril inhibits ACN-1 to control dauer formation and aging

The renin-angiotensin-aldosterone system (RAAS) plays a well-characterized role regulating blood pressure in mammals. Pharmacological and genetic manipulation of the RAAS has been shown to extend lifespan in Caenorhabditis elegans, Drosophila and rodents, but its mechanism is not well defined. Here, we investigate the angiotensin-converting enzyme (ACE) inhibitor drug captopril, which extends lifespan in worms and mice. To investigate the mechanism, we performed a forward genetic screen for captopril-hypersensitive mutants. We identified a missense mutation that causes a partial loss of function of the daf-2 receptor tyrosine kinase gene, a powerful regulator of aging. The homologous mutation in the human insulin receptor causes Donohue syndrome, establishing these mutant worms as an invertebrate model of this disease. Captopril functions in C. elegans by inhibiting ACN-1, the worm homolog of ACE. Reducing the activity of acn-1 via captopril or RNA interference promoted dauer larvae formation, suggesting that acn-1 is a daf gene. Captopril-mediated lifespan extension was abrogated by daf-16(lf) and daf-12(lf) mutations. Our results indicate that captopril and acn-1 influence lifespan by modulating dauer formation pathways. We speculate that this represents a conserved mechanism of lifespan control.

The role of Caenorhabditis elegans in the discovery of natural products for healthy aging

Covering: 2012 to 2023The human population is aging. Thus, the greatest risk factor for numerous diseases, such as diabetes, cancer and neurodegenerative disorders, is increasing worldwide. Age-related diseases do not typically occur in isolation, but as a result of multi-factorial causes, which in turn require holistic approaches to identify and decipher the mode of action of potential remedies. With the advent of C. elegans as the primary model organism for aging, researchers now have a powerful in vivo tool for identifying and studying agents that effect lifespan and health span. Natural products have been focal research subjects in this respect. This review article covers key developments of the last decade (2012-2023) that have led to the discovery of natural products with healthy aging properties in C. elegans. We (i) discuss the state of knowledge on the effects of natural products on worm aging including methods, assays and involved pathways; (ii) analyze the literature on natural compounds in terms of their molecular properties and the translatability of effects on mammals; (iii) examine the literature on multi-component mixtures with special attention to the studied organisms, extraction methods and efforts regarding the characterization of their chemical composition and their bioactive components. (iv) We further propose to combine small in vivo model organisms such as C. elegans and sophisticated analytical approaches ("wormomics") to guide the way to dissect complex natural products with anti-aging properties.