Measuring Oxidative Stress in Caenorhabditis elegans: Paraquat and Juglone Sensitivity Assays

Astaxanthin promotes the longevity of Caenorhabditis elegans via modulation of the intracellular redox status and PHA-4-mediated autophagy

Astaxanthin is a xanthophyll carotenoid which has been associated with a number of health-promoting effects, including anti-aging; however, the underlying mechanisms are not fully understood. In the present study, it was found that astaxanthin promoted the longevity of wild-type (N2) Caenorhabditis elegans (C. elegans). The lifespan-extending effect of astaxanthin was associated with a significant decrease of lipofuscin accumulation and the reduction of the age-related decline in spontaneous motility. Meanwhile, astaxanthin enhanced the oxidative stress resistance in C. elegans, preventing the elevation of the reactive oxygen species and alleviating juglone-induced toxicity. Further studies revealed that astaxanthin treatment induced the expression of the skn-1 gene; besides, the lifespan-extending effect of astaxanthin relied on SKN-1. Additionally, the expression of age-1, a PI3K homolog gene, and let-363, a target of the rapamycin (TOR) homolog gene, was decreased, while the expression of PHA-4, a transcription factor negatively regulated by TOR signaling, was increased by astaxanthin treatment. PHA-4 has been demonstrated to regulate the expression of genes playing critical roles in the autophagy-lysosome pathway (ALP). Consistently, several key genes related to ALP, including lgg-1, atg-5, vps-34, ncr-1 and asm-1 were upregulated in C. elegans treated with astaxanthin. Knockdown of pha-4 expression by siRNA prevented the elevation of the above ALP-related genes, while diminishing the lifespan-extension effect of astaxanthin. Overall, these results indicated that astaxanthin prolonged the lifespan of C. elegans via modulating the intracellular redox status and promoting PHA-4-mediated autophagy.

Synergistic Co-Cu Dual-Atom Nanozyme with Promoted Catalase-like Activity for Parkinson's Disease Treatment

Neurodegenerative diseases like Parkinson's disease (PD) are intimately associated with oxidative stress due to the excessive highly reactive oxygen species (ROS), leading to the damage of dopaminergic neurons. Herein, we develop a Co-Cu dual-atom nanozyme (CoCu-DAzyme) by uniformly anchoring Co and Cu active sites onto an AlO(OH) substrate that exhibits remarkable catalase-like catalytic activity, far exceeding that of the Co or Cu single-atom counterparts. The following density functional theory calculations reveal that the Co sites efficiently enable H2O2 adsorption, while Cu sites promote charge transfer, synergistically promoting the catalytic decomposition of H2O2 into H2O and O2. Encouragingly, the developed CoCu-DAzyme notably ameliorates α-synuclein aggregation and alleviates the motor dysfunction inCaenorhabditis elegansPD models by substantively scavenging in vivo ROS. This research shows a novel therapeutic strategy for oxidative-stress-related neurodegenerative disorders by developing well-engineered nanozymes.

Transcriptional responses to prolonged oxidative stress require cholinergic activation of G-protein-coupled receptor signaling

Organisms have evolved protective strategies that are geared toward limiting cellular damage and enhancing organismal survival in the face of environmental stresses, but how these protective mechanisms are coordinated remains unclear. Here, we define a requirement for neural activity in mobilizing the antioxidant defenses of the nematode Caenorhabditis elegans both during prolonged oxidative stress and prior to its onset. We show that acetylcholine-deficient mutants are particularly vulnerable to prolonged oxidative stress. We find that prolonged oxidative stress mobilizes a broad transcriptional response which is strongly dependent on both cholinergic signaling and activation of the muscarinic G-protein acetylcholine coupled receptor (mAChR) GAR-3. Gene enrichment analysis revealed a lack of upregulation of proteasomal proteolysis machinery in both cholinergic-deficient and gar-3 mAChR mutants, suggesting that muscarinic activation is critical for stress-responsive upregulation of protein degradation pathways. Further, we find that GAR-3 overexpression in cholinergic motor neurons prolongs survival during prolonged oxidative stress. Our studies demonstrate neuronal modulation of antioxidant defenses through cholinergic activation of G protein-coupled receptor signaling pathways, defining new potential links between cholinergic signaling, oxidative damage, and neurodegenerative disease.

Neuro-intestinal acetylcholine signalling regulates the mitochondrial stress response in Caenorhabditis elegans

Neurons coordinate inter-tissue protein homeostasis to systemically manage cytotoxic stress. In response to neuronal mitochondrial stress, specific neuronal signals coordinate the systemic mitochondrial unfolded protein response (UPRmt) to promote organismal survival. Yet, whether chemical neurotransmitters are sufficient to control the UPRmt in physiological conditions is not well understood. Here, we show that gamma-aminobutyric acid (GABA) inhibits, and acetylcholine (ACh) promotes the UPRmt in the Caenorhabditis elegans intestine. GABA controls the UPRmt by regulating extra-synaptic ACh release through metabotropic GABAB receptors GBB-1/2. We find that elevated ACh levels in animals that are GABA-deficient or lack ACh-degradative enzymes induce the UPRmt through ACR-11, an intestinal nicotinic α7 receptor. This neuro-intestinal circuit is critical for non-autonomously regulating organismal survival of oxidative stress. These findings establish chemical neurotransmission as a crucial regulatory layer for nervous system control of systemic protein homeostasis and stress responses.

The anti-aging effects of Chlorella polysaccharide extract in Caenorhabditis elegans

Chlorella has a variety of biological activities, and it is worth further exploring its pharmacological effects. In this study, we investigated the antioxidant and anti-ageing activities of Chlorella polysaccharide extract (CPE). Further studies revealed that CPE exhibited anti-ageing, and antioxidant activities in vivo, including an extended Caenorhabditis elegans stress resistance, decreased deposition of lipofuscin, and reduced effects of amyloid β protein on mobility, decreased levels of reactive oxygen species and increased activity of antioxidant enzymes. Moreover, it dramatically increased the expression of anti-stress and longevity genes and reduced the expression of ageing-related genes; therefore, it was hypothesised that the mechanism of the age-delaying effect of CPE was related to the insulin signalling pathway. In summary, CPE could delay ageing and provide a new avenue for the application and development of CPE.

Endogenous fluorescent reporters for heat shock proteins are not detectable after stress induction

Mitochondria and the endoplasmic reticulum (ER) utilise unique unfolded protein response (UPR) mechanisms to maintain cellular proteostasis. Heat shock proteins (HSPs) are UPR chaperones induced by specific stressors to promote protein folding. Previous research has successfully employed transgenic reporters in Caenorhabditis elegans to report HSP induction. However, transgenic reporters are overexpressed and only show promoter regulation and not post-transcriptional regulation. To examine endogenous HSP regulation, we attempted to generate and validate endogenous reporters for mitochondrial ( HSP-60 ) and ER ( HSP-4 ) chaperones. Using CRISPR/Cas9 technology, F2A-GFP-H2B coding DNA was inserted downstream of each HSP gene and stress induction assays conducted to validate these tools. Endogenous reporters were successfully generated for hsp-4 and hsp-60 . However, GFP induction could not be detected with these endogenous reporters upon stress induction, likely due to low level expression.

Ferulic acid grafted into β-cyclodextrin nanosponges ameliorates Paraquat-induced human MRC-5 fibroblast injury

Paraquat (PQ) is a commercially important and effective herbicide in the world. Nevertheless, it has higher toxicity causing acute organ damage and different complications, mainly in the lungs and kidneys. Ferulic acid (FA), 4-hydroxy-3-methoxycinnamic acid imposes multiple pharmacological impacts. No protective effect of FA on PQ poisoning-caused human embryonic lung fibroblast damage has not been reported. Despite their many beneficial effects, FA is characterized by poor water solubility, low bioavailability, and phytochemical instability. To solve the problem, β-cyclodextrin nanosponge (β-CD NSs) was utilized to increase the solubility of FA so that it was grafted into β-CD NSs to establish β-CD@FA NSs. The purpose of this work was to examine for the first time the protective effect of β-CD@FA NS on MRC-5 human lung cells damages induced by PQ poisoning. MTS assay was performed to investigate the viability of MRC-5 cells at different concentrations of FA/β-CD@FA NSs when cells were co-cultured with 0.2 μg/mL PQ. The flow cytometry study was carried out to determine apoptosis. Malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) levels were detected using appropriate biochemistry kits. Compared with the PQ group, the cell activity, CAT, and SOD levels were significantly increased in the FA and chiefly in β-CD@FA NSs intervention groups, whereas apoptosis and MDA levels were markedly decreased. The inflammatory factors tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), and interleukin 22 (IL-22) were detected. The results demonstrate that β-CD@FA NSs can inhibit PQ-induced cell damage by enhancing antioxidant stress capacity and regulation of inflammatory responses.

Icariin Improves Stress Resistance and Extends Lifespan in Caenorhabditis elegans through hsf-1 and daf-2-Driven Hormesis

Aging presents an increasingly significant challenge globally, driven by the growing proportion of individuals aged 60 and older. Currently, there is substantial research interest in pro-longevity interventions that target pivotal signaling pathways, aiming not only to extend lifespan but also to enhance healthspan. One particularly promising approach involves inducing a hormetic response through the utilization of natural compounds defined as hormetins. Various studies have introduced the flavonoid icariin as beneficial for age-related diseases such as cardiovascular and neurodegenerative conditions. To validate its potential pro-longevity properties, we employed Caenorhabditis elegans as an experimental platform. The accumulated results suggest that icariin extends the lifespan of C. elegans through modulation of the DAF-2, corresponding to the insulin/IGF-1 signaling pathway in humans. Additionally, we identified increased resistance to heat and oxidative stress, modulation of lipid metabolism, improved late-life healthspan, and an extended lifespan upon icariin treatment. Consequently, a model mechanism of action was provided for icariin that involves the modulation of various players within the stress-response network. Collectively, the obtained data reveal that icariin is a potential hormetic agent with geroprotective properties that merits future developments.

Methanol Extracts from Cirsium japonicum DC. var. australe Kitam. and Their Active Components Reduce Intracellular Oxidative Stress in Caenorhabditis elegans

Cirsium japonicum DC. var. australe Kitam. has been used as an herbal remedy and often involves using the whole plant or roots. However, the bioactivities of different parts of the plant have been far less explored. This study aimed to evaluate the antioxidative ability of methanol extracts from the flowers, leaves, stems, and roots of the Cirsium plant and their possible active components against juglone-induced oxidative stress in the nematode Caenorhabditis elegans. The results showed that the highest dry weight (12.3 g per plant) was observed in leaves, which was followed by stems (8.0 g). The methanol extract yields from the flowers, leaves, and roots were all similar (13.0-13.8%), while the yield from stems was the lowest (8.6%). The analysis of the silymarin contents in the extracts indicated that the flowers, leaves, stems, and roots contained silychristin and taxifolin; however, silydianin was only found in the leaves, stems, and roots. The flower, leaf, and stem extracts, at a concentration of 10 mg/L, significantly reduced juglone-induced oxidative stress in C. elegans, which was potentially due to the presence of silychristin and taxifolin. Overall, C. japonicum DC. var. australe Kitam. contains a significant amount of silymarin and exhibits in vivo antioxidative activity, suggesting that the prospects for the plant in terms of health supplements or as a source of silymarin are promising.

Endosomal trafficking protein TBC-2 is required for the longevity of long-lived mitochondrial mutants

Mutations that result in a mild impairment of mitochondrial function can extend longevity. Previous studies have shown that the increase in lifespan is dependent on stress responsive transcription factors, including DAF-16/FOXO, which exhibits increased nuclear localization in long-lived mitochondrial mutants. We recently found that the localization of DAF-16 within the cell is dependent on the endosomal trafficking protein TBC-2. Based on the important role of DAF-16 in both longevity and resistance to stress, we examined the effect of disrupting tbc-2 on lifespan and stress resistance in the long-lived mitochondrial mutants nuo-6 and isp-1 in Caenorhabditis elegans. Loss of tbc-2 markedly reduced the long lifespans of both mitochondrial mutants. Disruption of tbc-2 also decreased resistance to chronic oxidative stress in nuo-6 and isp-1 mutants but had little or no detrimental effect on resistance to other stressors. In contrast, tbc-2 inhibition had no effect on oxidative stress resistance or lifespan in isp-1 worms when DAF-16 is absent, suggesting that the effect of tbc-2 on mitochondrial mutant lifespan may be mediated by mislocalization of DAF-16. However, this result is complicated by the fact that deletion of daf-16 markedly decreases both phenotypes in isp-1 worms, which could result in a floor effect. In exploring the contribution of DAF-16 further, we found that disruption of tbc-2 did not affect the nuclear localization of DAF-16 in isp-1 worms or prevent the upregulation of DAF-16 target genes in the long-lived mitochondrial mutants. This suggests the possibility that the effect of tbc-2 on lifespan and stress resistance in the long-lived mitochondrial mutants is at least partially independent of its effects on DAF-16 localization. Overall, this work demonstrates the importance of endosomal trafficking for the extended longevity and enhanced stress resistance resulting from mild impairment of mitochondrial function.

Effects of Vegetal Extracts and Metabolites against Oxidative Stress and Associated Diseases: Studies in Caenorhabditis elegans

Oxidative stress is a natural physiological process where the levels of oxidants, such as reactive oxygen species (ROS) and nitrogen (RNS), exceed the strategy of antioxidant defenses, culminating in the interruption of redox signaling and control. Oxidative stress is associated with multiple pathologies, including premature aging, neurodegenerative diseases, obesity, diabetes, atherosclerosis, and arthritis. It is not yet clear whether oxidative stress is the cause or consequence of these diseases; however, it has been shown that using compounds with antioxidant properties, particularly compounds of natural origin, could prevent or slow down the progress of different pathologies. Within this context, the Caenorhabditis elegans (C. elegans) model has served to study the effect of different metabolites and natural compounds, which has helped to decipher molecular targets and the effect of these compounds on premature aging and some diseases such as neurodegenerative diseases and dyslipidemia. This article lists the studies carried out on C. elegans in which metabolites and natural extracts have been tested against oxidative stress and the pathologies associated with providing an overview of the discoveries in the redox area made with this nematode.

Endosomal trafficking protein TBC-2 modulates stress resistance and lifespan through DAF-16-dependent and independent mechanisms

The FOXO transcription factor, DAF-16, plays an integral role in insulin/IGF-1 signaling (IIS) and stress response. In conditions of stress or decreased IIS, DAF-16 moves to the nucleus where it activates genes that promote survival. To gain insight into the role of endosomal trafficking in resistance to stress, we disrupted tbc-2, which encodes a GTPase activating protein that inhibits RAB-5 and RAB-7. We found that tbc-2 mutants have decreased nuclear localization of DAF-16 in response to heat stress, anoxia, and bacterial pathogen stress, but increased nuclear localization of DAF-16 in response to chronic oxidative stress and osmotic stress. tbc-2 mutants also exhibit decreased upregulation of DAF-16 target genes in response to stress. To determine whether the rate of nuclear localization of DAF-16 affected stress resistance in these animals, we examined survival after exposure to multiple exogenous stressors. Disruption of tbc-2 decreased resistance to heat stress, anoxia, and bacterial pathogen stress in both wild-type worms and stress-resistant daf-2 insulin/IGF-1 receptor mutants. Similarly, deletion of tbc-2 decreases lifespan in both wild-type worms and daf-2 mutants. When DAF-16 is absent, the loss of tbc-2 is still able to decrease lifespan but has little or no impact on resistance to most stresses. Combined, this suggests that disruption of tbc-2 affects lifespan through both DAF-16-dependent and DAF-16-independent pathways, while the effect of tbc-2 deletion on resistance to stress is primarily DAF-16-dependent. Overall, this work demonstrates the importance of endosomal trafficking for the proper nuclear localization of DAF-16 during stress and that perturbation of normal endosomal trafficking is sufficient to decrease both stress resistance and lifespan.

Reduced Ribose-5-Phosphate Isomerase A-1 Expression in Specific Neurons and Time Points Promotes Longevity in Caenorhabditis elegans

Deregulation of redox homeostasis is often associated with an accelerated aging process. Ribose-5-phosphate isomerase A (RPIA) mediates redox homeostasis in the pentose phosphate pathway (PPP). Our previous study demonstrated that Rpi knockdown boosts the healthspan in Drosophila. However, whether the knockdown of rpia-1, the Rpi ortholog in Caenorhabditis elegans, can improve the healthspan in C. elegans remains unknown. Here, we report that spatially and temporally limited knockdown of rpia-1 prolongs lifespan and improves the healthspan in C. elegans, reflecting the evolutionarily conserved phenotypes observed in Drosophila. Ubiquitous and pan-neuronal knockdown of rpia-1 both enhance tolerance to oxidative stress, reduce polyglutamine aggregation, and improve the deteriorated body bending rate caused by polyglutamine aggregation. Additionally, rpia-1 knockdown temporally in the post-developmental stage and spatially in the neuron display enhanced lifespan. Specifically, rpia-1 knockdown in glutamatergic or cholinergic neurons is sufficient to increase lifespan. Importantly, the lifespan extension by rpia-1 knockdown requires the activation of autophagy and AMPK pathways and reduced TOR signaling. Moreover, the RNA-seq data support our experimental findings and reveal potential novel downstream targets. Together, our data disclose the specific spatial and temporal conditions and the molecular mechanisms for rpia-1 knockdown-mediated longevity in C. elegans. These findings may help the understanding and improvement of longevity in humans.

Structure and biological evaluation of Caenorhabditis elegans CISD-1/mitoNEET, a KLP-17 tail domain homologue, supports attenuation of paraquat-induced oxidative stress through a p38 MAPK-mediated antioxidant defense response

CISD-1/mitoNEET is an evolutionarily conserved outer mitochondrial membrane [2Fe-2S] protein that regulates mitochondrial function and morphology. The [2Fe-2S] clusters are redox reactive and shown to mediate oxidative stress in vitro and in vivo. However, there is limited research studying CISD-1/mitoNEET mediation of oxidative stress in response to environmental stressors. In this study, we have determined the X-ray crystal structure of Caenorhabditis elegans CISD-1/mitoNEET homologue and evaluated the mechanisms of oxidative stress resistance to the pro-oxidant paraquat in age-synchronized populations by generating C. elegans gain and loss of function CISD-1 models. The structure of the C. elegans CISD-1/mitoNEET soluble domain refined at 1.70-Å resolution uniquely shows a reversible disulfide linkage at the homo-dimeric interface and also represents the N-terminal tail domain for dimerization of the cognate kinesin motor protein KLP-17 involved in chromosome segregation dynamics and germline development of the nematode. Moreover, overexpression of CISD-1/mitoNEET in C. elegans has revealed beneficial effects on oxidative stress resistance against paraquat-induced reactive oxygen species generation, corroborated by increased activation of the p38 mitogen-activated protein kinase (MAPK) signaling cascade.

The hypoxia response pathway promotes PEP carboxykinase and gluconeogenesis in C. elegans

Actively dividing cells, including some cancers, rely on aerobic glycolysis rather than oxidative phosphorylation to generate energy, a phenomenon termed the Warburg effect. Constitutive activation of the Hypoxia Inducible Factor (HIF-1), a transcription factor known for mediating an adaptive response to oxygen deprivation (hypoxia), is a hallmark of the Warburg effect. HIF-1 is thought to promote glycolysis and suppress oxidative phosphorylation. Here, we instead show that HIF-1 can promote gluconeogenesis. Using a multiomics approach, we reveal the genomic, transcriptomic, and metabolomic landscapes regulated by constitutively active HIF-1 in C. elegans. We use RNA-seq and ChIP-seq under aerobic conditions to analyze mutants lacking EGL-9, a key negative regulator of HIF-1. We integrate these approaches to identify over two hundred genes directly and functionally upregulated by HIF-1, including the PEP carboxykinase PCK-1, a rate-limiting mediator of gluconeogenesis. This activation of PCK-1 by HIF-1 promotes survival in response to both oxidative and hypoxic stress. Our work identifies functional direct targets of HIF-1 in vivo, comprehensively describing the metabolome induced by HIF-1 activation in an organism.

A dimer-monomer switch controls CHIP-dependent substrate ubiquitylation and processing

The high substrate selectivity of the ubiquitin/proteasome system is mediated by a large group of E3 ubiquitin ligases. The ubiquitin ligase CHIP regulates the degradation of chaperone-controlled and chaperone-independent proteins. To understand how CHIP mediates substrate selection and processing, we performed a structure-function analysis of CHIP and addressed its physiological role in Caenorhabditis elegans and human cells. The conserved function of CHIP in chaperone-assisted degradation requires dimer formation to mediate proteotoxic stress resistance and to prevent protein aggregation. The CHIP monomer, however, promotes the turnover of the membrane-bound insulin receptor and longevity. The dimer-monomer transition is regulated by CHIP autoubiquitylation and chaperone binding, which provides a feedback loop that controls CHIP activity in response to cellular stress. Because CHIP also binds other E3 ligases, such as Parkin, the molecular switch mechanism described here could be a general concept for the regulation of substrate selectivity and ubiquitylation by combining different E3s.

Vitamin D3 promotes longevity in Caenorhabditis elegans

Vitamin D deficiency is associated with a variety of age-related diseases and is becoming increasingly more prevalent in the population over time. Some diseases associated with deficiency are cardiovascular disease, cancer, and neurodegeneration. This association, as well as the fact that vitamin D has been demonstrated to play an important role in a variety of extraskeletal processes, has led some to claim that vitamin D is an essential longevity vitamin. However, the role of vitamin D in healthy aging has been difficult to determine. In order to study vitamin D in the context of aging, the model organism, Caenorhabditis elegans (C. elegans), was employed. To study vitamin D's impact on aging and age-related disease, lifespan and health span were measured across three different genetic strains of C. elegans. Strains investigated were wildtype (N2), worms with a mutant vitamin D receptor ortholog (nhr-8), and worms engineered to represent Alzheimer disease (gnals2). Bioinformatic analysis of available public data was also performed in order to identify the transcriptional response produced in N2 worms treated with vitamin D₃. Treatment with vitamin D₃ significantly extended the lifespan of N2 worms and rescued nhr-8 worms, which typically have decreased lifespans compared to N2. Treatment with vitamin D₃ minimally extended the lifespan of gnals2 worms. Similar results were obtained for measures of health span, quantified as motility through time. Differentially expressed genes upon treatment with vitamin D₃ were largely associated with biological processes such as the innate immune response and metabolism of xenobiotic compounds in the worms, which may explain the observed increase in lifespan and health span.

Hyperactivation of the proteasome in Caenorhabditis elegans protects against proteotoxic stress and extends lifespan

Virtually all age-related neurodegenerative diseases (NDs) can be characterized by the accumulation of proteins inside and outside the cell that are thought to significantly contribute to disease pathogenesis. One of the cell’s primary systems for the degradation of misfolded/damaged proteins is the ubiquitin proteasome system (UPS), and its impairment is implicated in essentially all NDs. Thus, upregulating this system to combat NDs has garnered a great deal of interest in recent years. Various animal models have focused on stimulating 26S activity and increasing 20S proteasome levels, but thus far, none have targeted intrinsic activation of the 20S proteasome itself. Therefore, we constructed an animal model that endogenously expresses a hyperactive, open gate proteasome in Caenorhabditis elegans. The gate-destabilizing mutation that we introduced into the nematode germline yielded a viable nematode population with enhanced proteasomal activity, including peptide, unstructured protein, and ubiquitin-dependent degradation activities. We determined these nematodes showed a significantly increased lifespan and substantial resistance to oxidative and proteotoxic stress but a significant decrease in fecundity. Our results show that introducing a constitutively active proteasome into a multicellular organism is feasible and suggests targeting the proteasome gating mechanism as a valid approach for future age-related disease research efforts in mammals.

Citric Acid-Derived Carbon Quantum Dots Attenuate Paraquat-Induced Neuronal Compromise In Vitro and In Vivo

The potent environmental herbicide and weedicide paraquat is linked to neuromotor defects and Parkinson's disease (PD). We have evaluated the neuroprotective role of citric acid-sourced carbon quantum dots (Cit-CQDs) on paraquat-insulted human neuroblastoma-derived SH-SY5Y cell lines and on a paraquat-exposed nematode (Caenorhabditis elegans). Our data reveal that Cit-CQDs are able to scavenge free radicals in test tube assays and mitigate paraquat-elevated reactive oxygen species (ROS) levels in SH-SY5Y cells. Furthermore, Cit-CQDs protect the cell line from paraquat, which otherwise elicits cell death. Cit-CQDs-challenged nematodes demonstrate enhanced survival rates 72 h post-paraquat exposure compared to controls. Paraquat ablates dopamine (DA) neurons, which results in compromised locomotor function in nematodes. However, the neurons remained intact when the nematodes were incubated with Cit-CQDs prior to neurotoxicant exposure. The collective data suggest Cit-CQDs offer neuroprotection for cell lines and organisms from xenotoxicant-associated neuronal injury and death. The study suggests Cit-CQDs as a potentially viable green chemistry-synthesized, biobased nanomaterial for intervention in neurodegenerative disorders.

Mitochondrial thioredoxin system is required for enhanced stress resistance and extended longevity in long-lived mitochondrial mutants

Mild impairment of mitochondrial function has been shown to increase lifespan in genetic model organisms including worms, flies and mice. To better understand the mechanisms involved, we analyzed RNA sequencing data and found that genes involved in the mitochondrial thioredoxin system, trx-2 and trxr-2, are specifically upregulated in long-lived mitochondrial mutants but not other non-mitochondrial, long-lived mutants. Upregulation of trx-2 and trxr-2 is mediated by activation of the mitochondrial unfolded protein response (mitoUPR). While we decided to focus on the genes of the mitochondrial thioredoxin system for this paper, we identified multiple other antioxidant genes that are upregulated by the mitoUPR in the long-lived mitochondrial mutants including sod-3, prdx-3, gpx-6, gpx-7, gpx-8 and glrx-5. In exploring the role of the mitochondrial thioredoxin system in the long-lived mitochondrial mutants, nuo-6 and isp-1, we found that disruption of either trx-2 or trxr-2 significantly decreases their long lifespan, but has no effect on wild-type lifespan, indicating that the mitochondrial thioredoxin system is specifically required for their longevity. In contrast, disruption of the cytoplasmic thioredoxin gene trx-1 decreases lifespan in nuo-6, isp-1 and wild-type worms, indicating a non-specific detrimental effect on longevity. Disruption of trx-2 or trxr-2 also decreases the enhanced resistance to stress in nuo-6 and isp-1 worms, indicating a role for the mitochondrial thioredoxin system in protecting against exogenous stressors. Overall, this work demonstrates an important role for the mitochondrial thioredoxin system in both stress resistance and lifespan resulting from mild impairment of mitochondrial function.

C. elegans as an Animal Model to Study the Intersection of DNA Repair, Aging and Neurodegeneration

Since its introduction as a genetic model organism, Caenorhabditis elegans has yielded insights into the causes of aging. In addition, it has provided a molecular understanding of mechanisms of neurodegeneration, one of the devastating effects of aging. However, C. elegans has been less popular as an animal model to investigate DNA repair and genomic instability, which is a major hallmark of aging and also a cause of many rare neurological disorders. This article provides an overview of DNA repair pathways in C. elegans and the impact of DNA repair on aging hallmarks, such as mitochondrial dysfunction, telomere maintenance, and autophagy. In addition, we discuss how the combination of biological characteristics, new technical tools, and the potential of following precise phenotypic assays through a natural life-course make C. elegans an ideal model organism to study how DNA repair impact neurodegeneration in models of common age-related neurodegenerative diseases.

Gelatin-derived carbon quantum dots mitigate herbicide-induced neurotoxic effects in vitro and in vivo

The herbicide and viologen, N, N'-dimethyl-4,4'-bipyridinium dichloride (Paraquat) is known to be toxic to neuronal cells by a multifactorial process involving an elevation in the levels of reactive oxygen species (ROS), the triggering of amyloid-protein aggregation and their accumulation, collectively leading to neuronal dyshomeostasis. We demonstrate that green-chemistry-synthesized sustainable gelatin-derived carbon quantum dots (CQDs) mitigate paraquat-induced neurotoxic outcomes and resultant compromise in organismal mortality. Gelatin-derived CQDs were found to possess antioxidant properties and ameliorated ROS elevation in paraquat-insulted neuroblastoma-derived SHSY-5Y cells, protecting them from herbicide-induced cell death. These CQDs also increased lifespan in paraquat-compromised Caenorhabditis elegans and herbicide-mediated dopamine neuron ablation. Collectively, the data underscore the ability of this sustainably synthesized, environmentally friendly biocompatible nanomaterial to protect cell lines and organisms against neurotoxic outcomes. The study findings strategically position this relatively novel nanoscopic carbon quantum framework for further testing in vertebrate trials of neurotoxic insult.

Current Understanding of Modes of Action of Multicomponent Bioactive Phytochemicals: Potential for Nutraceuticals and Antimicrobials

Plants produce a diversity of plant secondary metabolites (PSMs), which function as defense chemicals against herbivores and microorganisms but also as signal compounds. An individual plant produces and accumulates mixtures of PSMs with different structural features using different biosynthetic pathways. Almost all PSMs exert one or several biological activities that can be useful for nutrition and health. This review discusses the modes of action of PSMs alone and in combinations. In a mixture, most individual PSMs can modulate different molecular targets; they are thus multitarget drugs. In an extract with many multitarget chemicals, additive and synergistic effects occur. Experiments with the model system Caenorhabditis elegans show that polyphenols and carotenoids can function as powerful antioxidative and longevity-promoting PSMs. PSMs of food plants and spices often exhibit antioxidant, anti-inflammatory, and antimicrobial properties, which can be beneficial for health and the prevention of diseases. Some extracts from food plants and spices with bioactive PSMs have potential for nutraceuticals and antimicrobials.

Small-Molecule Mn Antioxidants in Caenorhabditis elegans and Deinococcus radiodurans Supplant MnSOD Enzymes during Aging and Irradiation

Denham Harman's oxidative damage theory identifies superoxide (O₂^•-) radicals as central agents of aging and radiation injury, with Mn²⁺-dependent superoxide dismutase (MnSOD) as the principal O₂^•--scavenger. However, in the radiation-resistant nematode Caenorhabditis elegans, the mitochondrial antioxidant enzyme MnSOD is dispensable for longevity, and in the model bacterium Deinococcus radiodurans, it is dispensable for radiation resistance. Many radiation-resistant organisms accumulate small-molecule Mn²⁺-antioxidant complexes well-known for their catalytic ability to scavenge O₂^•-, along with MnSOD, as exemplified by D. radiodurans. Here, we report experiments that relate the MnSOD and Mn-antioxidant content to aging and oxidative stress resistances and which indicate that C. elegans, like D. radiodurans, may rely on Mn-antioxidant complexes as the primary defense against reactive oxygen species (ROS). Wild-type and ΔMnSOD D. radiodurans and C. elegans were monitored for gamma radiation sensitivities over their life spans while gauging Mn²⁺-antioxidant content by electron paramagnetic resonance (EPR) spectroscopy, a powerful new approach to determining the in vivo Mn-antioxidant content of cells as they age. As with D. radiodurans, MnSOD is dispensable for radiation survivability in C. elegans, which hyperaccumulates Mn-antioxidants exceptionally protective of proteins. Unexpectedly, ΔMnSOD mutants of both the nematodes and bacteria exhibited increased gamma radiation survival compared to the wild-type. In contrast, the loss of MnSOD renders radiation-resistant bacteria sensitive to atmospheric oxygen during desiccation. Our results support the concept that the disparate responses to oxidative stress are explained by the accumulation of Mn-antioxidant complexes which protect, complement, and can even supplant MnSOD. IMPORTANCE The current theory of cellular defense against oxidative damage identifies antioxidant enzymes as primary defenders against ROS, with MnSOD being the preeminent superoxide (O₂^•-) scavenger. However, MnSOD is shown to be dispensable both for radiation resistance and longevity in model organisms, the bacterium Deinococcus radiodurans and the nematode Caenorhabditis elegans. Measured by electron paramagnetic resonance (EPR) spectroscopy, small-molecule Mn-antioxidant content was shown to decline in unison with age-related decreases in cell proliferation and radioresistance, which again are independent of MnSOD presence. Most notably, the Mn-antioxidant content of C. elegans drops precipitously in the last third of its life span, which links with reports that the steady-state level of oxidized proteins increases exponentially during the last third of the life span in animals. This leads us to propose that global responses to oxidative stress must be understood through an extended theory that includes small-molecule Mn-antioxidants as potent O₂^•--scavengers that complement, and can even supplant, MnSOD.

Sonneradon A Extends Lifespan of Caenorhabditis elegans by Modulating Mitochondrial and IIS Signaling Pathways

Aging is related to the lowered overall functioning and increased risk for various age-related diseases in humans. Sonneradon A (SDA), a new compound first extracted from the edible fruits of mangrove Sonneratia apetala, showed remarkable antiaging activity. However, the role of SDA in antiaging remains unclear. In this article, we studied the function of SDA in antiaging by using the animal model Caenorhabditis elegans. Results showed that SDA inhibited production of reactive oxygen species (ROS) by 53%, and reduced the accumulation of aging markers such as lipids and lipofuscins. Moreover, SDA also enhanced the innate immune response to Pseudomonas aeruginosa infection. Genetic analysis of a series of mutants showed that SDA extended the lifespan of the mutants of eat-2 and glp-1. Together, this effect may be related to the enhanced resistance to oxidative stress via mitochondrial and insulin/insulin-like growth factor-1 signaling (IIS) pathways. The results of this study provided new evidence for an antiaging effect of SDA in C. elegans, as well as insights into the implication of antiaging activity of SDA in higher organisms.

Neuromodulatory potential of Asparagus racemosus and its bioactive molecule Shatavarin IV by enhancing synaptic acetylcholine level and nAChR activity

Cholinergic dysfunction has been commonly known to be associated with plethora of neurodegenerative disorders and also serves as a biomarker. Recently, cholinergic system demonstrated that acetylcholine has major role in regulation of its function therefore the main therapeutic regimens towards disease management have been focused on increasing acetylcholine levels. The current study explores the potential of Asparagus racemosus extract (ARE) and its bioactive molecule Shatavarin IV (SIV) in improving cholinergic transmission via utilizing Caenorhabditis elegans considering as a model system. Observations and results obtained through this study have clearly showed significant modulation in cholinergic function by increasing acetylcholine (ACh) levels and the nicotinic acetylcholine receptors (nAChRs) activity. Further exploration on mechanistic facet pointed towards ARE and SIV modulatory potential through increased synaptic ACh level by blocking acetyl cholinesterase at enzyme level and by regulating increment in transcript level of cha-1, and cho-1 that are directly responsible for the synthesis of ACh. Further, the up-regulation of unc-38 and unc-50 transcripts could be the reason for enhanced nAChR activity and investigation on stress modulator activity showed excellent efficiency of ARE and SIV in diminishing ROS thereby lowering the oxidative damage.

Cannabinoid receptor agonist WIN55212-2 reduces unpredictable mild stress-induced depressive behavior of rats

Background

Depression is a neurological disorder characterized by persistent low mood. A number of studies have suggested that the use of type 1 cannabinoid receptor (CB1R) agonists can reduce depressive behavior, but its effect on the depressive behavior and nerve damage of rats exposed to chronic unpredictable mild stress (CUMS) has not been reported.

Methods

Rats were exposed to CUMS for 4 weeks to induce depressive behavior. Male Sprague-Dawley (SD) rats aged 6–8 weeks were randomly divided into six groups: control group (control), depression group (CUMS), depression + fluoxetine group (Flu), depression + WIN55212-2 group (WIN), depression + NF-κB inhibitor group (PDTC), and depression + WIN + PDTC group (WIN + PDTC). We performed four behavioral experiments test to evaluate the depressive behaviors of rats. Hematoxylin and eosin (HE) and Nissl staining were performed to observe the neuron structures of the hippocampus. Enzyme-linked immunosorbent assay (ELISA) was used to measure the concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2). Biochemical experiments were performed to evaluate the concentrations of nitric oxide (NO), malondialdehyde (MDA), reactive oxygen species (ROS), and superoxide dismutase (SOD). Fluorescence quantitative PCR was used to detect the mRNA expression of brain-derived neurotrophic factor (BDNF), tyrosine kinase receptor B (TrkB), and inducible nitric oxide synthase (iNOS) in the hippocampus, and western blot was performed to detect protein expression levels related to the NF-κB signaling pathway in the hippocampus.

Results

Compared with the normal control group, CUMS significantly induced abnormal behaviors in stressed rats. The concentrations of pro-inflammatory factors and oxidative stress injury factors in the hippocampus of the CUMS group increased significantly. The interventions of Flu, WIN, and PDTC significantly reduced neuroinflammation and oxidative stress injury. Compared with the WIN group, the WIN + PDTC intervention group had better results. In addition, WIN could significantly inhibit the activation of the NF-κB signaling pathway.

Conclusions

This study showed that cannabinoid receptor agonists can reduce the CUMS-induced depressive behaviors of rats by blocking the NF-κB signaling pathway to alleviate neuroinflammation and oxidative stress injury.

The triterpenoid ursolic acid ameliorates stress in Caenorhabditis elegans by affecting the depression-associated genes skn-1 and prdx2

INTRODUCTION

Depression is one of the leading causes of death worldwide. Lower antioxidant concentrations and increased oxidative stress levels contribute to the development of depression. Effective and tolerable medications are urgently needed. Nrf2 and PRDX2 are promising targets in the treatment of oxidative stress and, therefore, promising for the development of novel antidepressants. Ursolic acid (UA), a natural triterpenoid found in various plants is known to exert neuroprotective and antioxidant effects. Skn-1 (which corresponds to human Nrf2) and prdx2 deficient mutants of the nematode Caenorhabditis elegans are suitable models to study the effect of UA on these targets. Additionally, stress assays are used to mimic stress or depressed state.

METHODS

We examined the antioxidant activity of UA in Caenorhabditis elegans wildtype and skn-1- and prdx2-deficient strains by H2DCF-DA and juglone assays as well as osmotic and heat stress assays. Additionally, we analyzed the binding of UA to human PRDX2 and Skn-1 proteins by molecular docking and microscale thermophoresis.

RESULTS

UA exerted strong antioxidant activities. Additionally, induction of stress resistance towards osmotic and heat stress was observed. qRT-PCR revealed that UA upregulated the gene expression of skn-1 and prdx2. Molecular docking studies supported these findings.

CONCLUSION

Our findings implicate that the strong antioxidant activity of UA may exert anti-depressive effects by its interaction with the Skn-1 transcription factor, which is part of a detoxification network, and the antioxidant PRDX2 protein, which protects the organism from the detrimental effects of radical oxygen species.

Induction of stress resistance and extension of lifespan in Chaenorhabditis elegans serotonin-receptor knockout strains by withanolide A

INTRODUCTION

Approximately 300 million people worldwide suffer from depression. The COVID-19 crisis may dramatically increase these numbers. Severe side effects and resistance development limit the use of standard antidepressants. The steroidal lactone withanolide A (WA) from Withania somnifera may be a promising alternative. Caenorhabditis elegans was used as model to explore WA's anti-depressive and anti-stress potential.

METHODS

C. elegans wildtype (N2) and deficient strains (AQ866, DA1814, DA2100, DA2109 and MT9772) were used to assess oxidative, osmotic or heat stress as measured by generation of reactive oxygen species (ROS), determination of lifespan, and mRNA expression of serotonin receptor (ser-1, ser-4, ser-7) and serotonin transporter genes (mod-5). The protective effect of WA was compared to fluoxetine as clinically established antidepressant. Additionally, WA's effect on lifespan was determined. Furthermore, the binding affinities and pKi values of WA, fluoxetine and serotonin as natural ligand to Ser-1, Ser-4, Ser-7, Mod-5 and their human orthologues proteins were calculated by molecular docking.

RESULTS

Baseline oxidative stress was higher in deficient than wildtype worms. WA and fluoxetine reduced ROS levels in all strains except MT9772. WA and fluoxetine prolonged survival times in wildtype and mutants under osmotic stress. WA but not fluoxetine increased lifespan of all heat-stressed C. elegans strains except DA2100. Furthermore, WA but not fluoxetine extended lifespan in all non-stressed C. elegans strains. WA also induced mRNA expression of serotonin receptors and transporters in wildtype and mutants. WA bound with higher affinity and lower pKi values to all C. elegans and human serotonin receptors and transporters than serotonin, indicating that WA may competitively displaced serotonin from the binding pockets of these proteins.

CONCLUSION

WA reduced stress and increased lifespan by ROS scavenging and interference with the serotonin system. Hence, WA may serve as promising candidate to treat depression.

Ursolic acid enhances stress resistance, reduces ROS accumulation and prolongs life span in C. elegans serotonin-deficient mutants

INTRODUCTION

Depression and anxiety disorders contribute to the global disease burden. Ursolic acid (UA), a natural compound present in many vegetables, fruits and medicinal plants, was tested in vivo for its effect on (1) enhancing resistance to stress and (2) its effect on life span.

METHODS

The compound was tested for its antioxidant activity in C. elegans. Stress resistance was tested in the heat and osmotic stress assay. Additionally, the influence on normal life span was examined. RT-PCR was used to assess possible serotonin targets.

RESULTS

UA prolonged the life span of C. elegans. Additionally, UA significantly lowered reactive oxygen species (ROS). Molecular docking studies, PCR analysis and microscale thermophoresis (MST) supported the results that UA acts through serotonin receptors to enhance stress resistance.

DISCUSSION

Considering the urgent need for new and safe medications in the treatment of depression and anxiety disorders, our results indicate that UA may be a promising new drug candidate.

Saul-Wilson Syndrome Missense Allele Does Not Show Obvious Golgi Defects in a C. elegans Model

Saul-Wilson Syndrome is an ultra-rare skeletal syndrome caused by a mutation in the COG4 gene resulting in a glycine-to-arginine substitution at amino acid position 516. The COG4 gene encodes one of 8 subunits of the conserved oligomeric Golgi complex. Using CRISPR-Cas9, our lab generated a C. elegans model for Saul-Wilson Syndrome by recreating the same glycine-to-arginine substitution in the worm ortholog cogc-4. Upon observation, the cogc-4(av107) worms did not display any obvious differences compared to wild-type worms. We used a variety of assays including stressing the worms using heat and Paraquat, as well as RNAi against the 7 other COG complex subunit genes in an attempt to uncover a phenotype. Our data suggest that this mutation in cogc-4(av107) worms does not lead to a detectable phenotype. Further studies should aim at more directly assessing Golgi function in this disease model.

Sulforaphane promotes C. elegans longevity and healthspan via DAF-16/DAF-2 insulin/IGF-1 signaling

The broccoli-derived isothiocyanate sulforaphane inhibits inflammation, oxidative stress and cancer, but its effect on healthspan and longevity are unclear. We used the C. elegans nematode model and fed the wildtype and 9 mutant strains ±sulforaphane. The lifespan, phenotype, pharyngeal pumping, mobility, lipofuscin accumulation, and RNA and protein expression of the nematodes were assessed by using Kaplan-Meier survival analysis, in vivo live imaging, fluorescence microscopy, and qRT-PCR. Sulforaphane increased the lifespan and promoted a health-related phenotype by increasing mobility, appetite and food intake and reducing lipofuscin accumulation. Mechanistically, sulforaphane inhibited DAF-2-mediated insulin/insulin-like growth factor signaling and its downstream targets AGE-1, AKT-1/AKT-2. This was associated with increased nuclear translocation of the FOXO transcription factor homolog DAF-16. In turn, the target genes sod-3, mtl-1 and gst-4, known to enhance stress resistance and lifespan, were upregulated. These results indicate that sulforaphane prolongs the lifespan and healthspan of C. elegans through insulin/IGF-1 signaling. Our results provide the basis for a nutritional sulforaphane-enriched strategy for the promotion of healthy aging and disease prevention.

Modeling paraquat-induced lung fibrosis in C. elegans reveals KRIT1 as a key regulator of collagen gene transcription

Paraquat poisoning causes lung fibrosis, which often results in long-term pulmonary dysfunction. Lung fibrosis has been attributed to collagens accumulation, but the underlying regulatory pathway remains unclear. Here we use the genetically tractable C. elegans as a model to study collagen gene transcription in response to paraquat. We find that paraquat robustly up-regulates collagen gene transcription, which is dependent on KRI-1, a poorly studied protein homologous to human KRIT1/CCM1. KRI-1 knockdown prevents paraquat from activating the oxidative stress response transcription factor SKN-1/Nrf2, resulting in reduced collagen transcription and increased paraquat sensitivity. Using human lung fibroblasts (MRC-5), we confirm that both KRIT1 and Nrf2 are required for collagen transcription in response to paraquat. Nrf2 hyper-activation by KEAP1 knockdown bypasses KRIT1 to up-regulate collagen transcription. Our findings on the regulation of collagen gene transcription by paraquat could suggest potential strategies to treat pulmonary fibrosis caused by paraquat poisoning.

Ursolic acid ameliorates stress and reactive oxygen species in C. elegans knockout mutants by the dopamine Dop1 and Dop3 receptors

BACKGROUND

Depression and stress-related disorders are leading causes of death worldwide. Standard treatments elevating serotonin or noradrenaline levels are not sufficiently effective and cause adverse side effects. A connection between dopamine pathways and stress-related disorders has been suggested. Compounds derived from herbal medicine could be a promising alternative. We examined the neuroprotective effects of ursolic acid (UA) by focusing on dopamine signalling.

METHODS

Trolox equivalent capacity assay was used to determine the antioxidant activities of UA in vitro. C. elegans N2 wildtype and dopamine receptor-knockout mutants (dop1-deficient RB665 and dop3-deficient LX703 strains) were used as in vivo models. H2DCFDA and acute juglone assays were applied to determine the antioxidant activity in dependency of dopamine pathways in vivo. Stress was assessed by heat and acute osmotic stress assays. The influence of UA on overall survival was analyzed by a life span assay. The dop1 and dop3 mRNA expression was determined by real time RT-PCR. We also examined the binding affinity of UA towards C. elegans Dop1 and Dop3 receptors as well as human dopamine receptors D1 and D3 by molecular docking.

RESULTS

Antioxidant activity assays showed that UA exerts strong antioxidant activity. UA increased resistance towards oxidative, osmotic and heat stress. Additionally, UA increased life span of nematodes. Moreover, dop1 and dop3 gene expression was significantly enhanced upon UA treatment. Docking analysis revealed stronger binding affinity of UA to C. elegans and human dopamine receptors than the natural ligand, dopamine. Binding to Dop1 was stronger than to Dop3.

CONCLUSION

UA reduced stress-dependent ROS generation and acted through Dop1 and to a lesser extent through Dop3 to reduce stress and prolong life span in C. elegans. These results indicate that UA could be a promising lead compound for the development of new antidepressant medications.

Neurotherapeutic effect of Hyptis spp. leaf extracts in Caenorhabditis elegans models of tauopathy and polyglutamine disease: Role of the glutathione redox cycle

Hyptis suaveolens (HS), Hyptis pectinata (HP) and Hyptis marrubioides (HM) are plants used in folk medicine for treatment of several diseases. Here, we tested the in vivo antioxidant and neuroprotective potential of methanolic extracts from these plants, containing several rosmarinic acid derivatives and isoquercetin. In C. elegans, HS, HP and HM leaf extracts enhanced the antioxidant responses through the induction of specific antioxidant enzymes and demonstrated neurotherapeutic potential in transgenic models of genetically determined human neurodegenerative diseases - Frontotemporal dementia with parkinsonism linked to chromosome 17 and Machado-Joseph disease. Chronic treatment of disease models with HS, HP and HM leaf extracts improved the animals' motor function and increased their tolerance to an oxidative insult. The restorative effect of HM extract in motor performance of both disease models required the presence of glutathione reductase (gsr-1), an enzyme that assures the glutathione redox cycle, highlighting the role of this pathway and unveiling a common candidate therapeutic target for these diseases. Our findings strengthen the relevance of plant-derived bioactive compound discovery for neurodegenerative disorders that remain without effective treatment.

G protein-coupled receptor kinase 2 modifies the ability of Caenorhabditis elegans to survive oxidative stress

Survival and adaptation to oxidative stress is important for many organisms, and these occur through the activation of many different signaling pathways. In this report, we showed that Caenorhabditis (C.) elegans G protein-coupled receptor kinases modified the ability of the organism to resist oxidative stress. In acute oxidative stress studies using juglone, loss-of-function grk-2 mutants were more resistant to oxidative stress compared with loss-of-function grk-1 mutants and the wild-type N2 animals. This effect was Ce-AKT-1 dependent, suggesting that Ce-GRK2 adjusted C. elegans oxidative stress resistance through the IGF/insulin-like signaling (IIS) pathway. Treating C. elegans with a GRK2 inhibitor, the selective serotonin reuptake inhibitor paroxetine, resulted in increased acute oxidative stress resistance compared with another selective serotonin reuptake inhibitor, fluoxetine. In chronic oxidative stress studies with paraquat, both grk-1 and grk-2 mutants had longer lifespan compared with the wild-type N2 animals in stress. In summary, this research showed the importance of both GRKs, especially GRK2, in modifying oxidative stress resistance.

Carnitine promotes recovery from oxidative stress and extends lifespan in C. elegans

Carnitine is required for transporting fatty acids into the mitochondria for β-oxidation. Carnitine has been used as an energy supplement but the roles in improving health and delaying aging remain unclear. Here we show in C. elegans that L-carnitine improves recovery from oxidative stress and extends lifespan. L-carnitine promotes recovery from oxidative stress induced by paraquat or juglone and improves mobility and survival in response to H₂O₂ and human amyloid (Aβ) toxicity. L-carnitine also alleviates the oxidative stress during aging, resulting in moderate but significant lifespan extension, which was dependent on SKN-1 and DAF-16. Long-lived worms with germline loss (glp-1) or reduced insulin receptor activity (daf-2) recover from aging-associated oxidative stress faster than wild-type controls and their long lifespans were not further increased by L-carnitine. A new gene, T08B1.1, aligned to a known carnitine transporter OCTN1 in humans, is required for L-carnitine uptake in C. elegans. T08B1.1 expression is elevated in daf-2 and glp-1 mutants and its knockdown prevents L-carnitine from improving oxidative stress recovery and prolonging lifespan. Together, our study suggests an important role of L-carnitine in oxidative stress recovery that might be important for healthy aging in humans.

Piquiá Shells (Caryocar villosum): A Fruit by-Product with Antioxidant and Antiaging Properties in Caenorhabditis elegans

In a context of rising demand for sustainable antiaging interventions, fruit processing by-products are a promising source of bioactive compounds for the production of antiaging dietary supplements. Piquiá (Caryocar villosum) is a native Amazonian fruit consisting of 65% nonedible shells. In the present study, the phytochemical profile of a hydroalcoholic extract of piquiá shells (CV) was characterized by LC-MS/MS analysis. Its antioxidant and antiaging activities were investigated using the nematode Caenorhabditis elegans as an in vivo model. CV is mainly composed by hydrolysable tannins and triterpenoid saponins. The extract enhanced stress resistance of wild-type and mutant worms by reducing the intracellular levels of reactive oxygen species (ROS) and by increasing their survival against a lethal dose of the prooxidant juglone. These effects involved the upregulation of sod-3 and downregulation of gst-4 and hsp-16.2, studied through the GFP fluorescent reporter intensity and at the transcriptional level by qRT-PCR analysis. CV extended the lifespan of wild-type worms in a DAF-16/FoxO- and SKN-1/Nrf-dependent manner. Taken together, our findings indicate piquiá shells as potential candidates for nutraceutical applications. Further studies are needed to validate the relevance of our findings to antiaging interventions in humans.

Hemiterpene compound, 3,3-dimethylallyl alcohol promotes longevity and neuroprotection in Caenorhabditis elegans

Terpenes and their derivatives have been used conventionally as potential dietary supplements to boost the nutritional value of endless food products. Several plant-based complex terpenoid and their derivatives have been reported for a wide range of medicinal and nutritional properties. However, their simple counterparts, whose production is relatively easy, sustainable, and economic from food-grade microbial sources, have not been studied yet for any such biological activities. The present study aimed to investigate the longevity-promoting property and neuromodulatory effects of 3,3-dimethylallyl alcohol (Prenol), one of the simplest forms of terpenoid and a constituent of fruit aroma, in the animal model Caenorhabditis elegans. Prenol supplementation (0.25 mM) augmented the lifespan of wild-type nematodes by 22.8% over the non-treated worms. Moreover, a suspended amyloid-β induced paralysis and reduced α-synuclein aggregation were observed in Prenol-treated worms. The lifespan extending properties of Prenol were correlated with ameliorated physiological parameters and increased stress (heat and oxidative) tolerance in C. elegans. In silico and gene-specific mutant studies showed that pro-longevity transcription factors DAF-16, HSF-1, and SKN-1 were involved in the improved lifespan and health-span of Prenol-treated worms. Transgenic green fluorescent protein-reporter gene expression analysis and relative mRNA quantification (using real-time PCR) demonstrated an increase in the expression of DAF-16, HSF-1, and SKN-1 transcription factors and their downstream target genes in Prenol-treated worms. Together, the findings suggest that small molecules, like Prenol, could be explored as a potential alternate to develop therapeutics against aging and age-related ailments.

Protective Effect and Mechanism of Fruit Extract of Aegle marmelos Against Amyloid-β Toxicity in a Transgenic Caenorhabditis elegans

Alzheimer’s disease (AD) is the most common form of dementia found in the elderly. AD is caused by the accumulation of toxic proteins including amyloid-β (Aβ). The purpose of this study was to investigate the effect of fruit extract of Aegle marmelos against Aβ toxicity in Caenorhabditis elegans. The fruit of A. marmelos has been used in a traditional Thai herb formula in fatigue patients recovering from illnesses such as fever and diarrhea. We used a transgenic C. elegans strain CL4176, which expresses the human Aβ42, to investigate the effects and the mechanisms of action of the extracts against Aβ toxicity. The extract of A. marmelos significantly delayed Aβ-induced paralysis. Aegle marmelos lost the ability to delay Aβ-induced paralysis in worms fed with daf-16 ribonucleic acid interference (RNAi) bacteria, but not in worms fed with hsf-1 and skin-1 RNAi bacteria. These results indicated that daf-16 transcription factor was required for A. marmelos-mediated delayed paralysis. Aegle marmelos enhanced the level of daf-16 gene. Taken together, these results indicated that A. marmelos reduced Aβ toxicity via the DAF-16-mediated cell signaling pathway. In addition, A. marmelos reduced toxic Aβ oligomers. Aegle marmelos also displayed antioxidative effect in in vivo as it enhanced resistance to paraquat-induced oxidative stress in wild type worms. All of the results suggested that A. marmelos can protect against Aβ-induced toxicity and can be a potential candidate for the prevention or treatment of AD.

Polydatin relieves paraquat-induced human MRC-5 fibroblast injury through inhibiting the activation of the NLRP3 inflammasome

Background

Paraquat (PQ) is a herbicide that is highly toxic to the lungs and kidneys. When it enters the body, it will disrupt the balance of the microenvironment in the body, induce a large number of inflammatory factors and cause cell damage. Polydatin (PD), resveratrol glycoside, has multiple pharmacological effects. However, the protective effect of PD on human embryo lung fibroblast damage caused by PQ poisoning has not been reported. The purpose of this study was to investigate the regulatory effect of PD on human embryo lung fibroblast damage caused by PQ poisoning.

Method

The optimal experimental concentration of PQ for human embryonic lung fibroblast MRC-5 was 100 µmol/L, and then the cells of 100 µmol/L PQ group were treated with different concentrations of PD for 24 h. MTT assay to detect MRC-5 cell viability and flow cytometry to detect apoptosis. The corresponding kit was used to detect the contents of glutathione peroxidase (GSH-PX), malondialdehyde (MDA) and superoxide dismutase (SOD). Enzyme-linked immunosorbent assay (ELISA) to detect the levels of related inflammatory factors tumor necrosis factor alpha (TNF-α), transforming growth factor beta (TGF-β), interleukin 1 beta (IL-1β), and interleukin 6 (IL-6). Western blot detection of NLRP3 inflammatory body activation-related protein expression.

Results

Compared with the PQ group, cell activity, GSH-Px content, and SOD content in PD intervention group were significantly increased, while apoptosis, MDA content, inflammatory factor level, and activation-related proteins of the NLRP3 inflammasome were significantly reduced and were dose-dependent.

Conclusions

PD can relieve PQ-induced human MRC-5 fibroblasts injury by reducing the inflammatory response, improving the antioxidant stress capacity, and inhibiting the activation of the NLRP3 inflammasome.

Measurements of Physiological Stress Responses in C. Elegans

Organisms are often exposed to fluctuating environments and changes in intracellular homeostasis, which can have detrimental effects on their proteome and physiology. Thus, organisms have evolved targeted and specific stress responses dedicated to repair damage and maintain homeostasis. These mechanisms include the unfolded protein response of the endoplasmic reticulum (UPR^ER), the unfolded protein response of the mitochondria (UPR^MT), the heat shock response (HSR), and the oxidative stress response (OxSR). The protocols presented here describe methods to detect and characterize the activation of these pathways and their physiological consequences in the nematode, C. elegans. First, the use of pathway-specific fluorescent transcriptional reporters is described for rapid cellular characterization, drug screening, or large-scale genetic screening (e.g., RNAi or mutant libraries). In addition, complementary, robust physiological assays are described, which can be used to directly assess sensitivity of animals to specific stressors, serving as functional validation of the transcriptional reporters. Together, these methods allow for rapid characterization of the cellular and physiological effects of internal and external proteotoxic perturbations.

Disruption of mitochondrial dynamics increases stress resistance through activation of multiple stress response pathways

Mitochondria are dynamic organelles that can change shape and size depending on the needs of the cell through the processes of mitochondrial fission and fusion. In this work, we investigated the role of mitochondrial dynamics in organismal stress response. By using C. elegans as a genetic model, we could visualize mitochondrial morphology in a live organism with well‐established stress assays and well‐characterized stress response pathways. We found that disrupting mitochondrial fission (DRP1/drp‐1) or fusion (OPA1/eat‐3, MFN/fzo‐1) genes caused alterations in mitochondrial morphology that impacted both mitochondrial function and physiologic rates. While both mitochondrial fission and mitochondrial fusion mutants showed increased sensitivity to osmotic stress and anoxia, surprisingly we found that the mitochondrial fusion mutants eat‐3 and fzo‐1 are more resistant to both heat stress and oxidative stress. In exploring the mechanism of increased stress resistance, we found that disruption of mitochondrial fusion genes resulted in the upregulation of multiple stress response pathways. Overall, this work demonstrates that disrupting mitochondrial dynamics can have opposite effects on resistance to different types of stress. Our results suggest that disruption of mitochondrial fusion activates multiple stress response pathways that enhance resistance to specific stresses.

Hydrogen extends Caenorhabditis elegans longevity by reducing reactive oxygen species

At present, a large number of studies have reported that hydrogen has antioxidant functions and prevents oxidative stress damage. However, it is not clear whether hydrogen can prolong longevity based on these effects. Therefore, we studied and explored the antiaging potential of exogenous hydrogen and its ability to extend longevity using Caenorhabditis elegans (C. elegans) as an animal model. Our results showed that the lifespans of the N2, sod-3 and sod-5 mutant strains were extended by approximately 22.7%, 9.5%, and 8.7%, respectively, after hydrogen treatment, but hydrogen had no effect on the lifespans of the daf-2 and daf-16 mutant strains. Meanwhile, the level of reactive oxygen species (ROS) in the hydrogen treatment group was significantly lower than that in the control group. At the transcript level, the expression of age-1 and let-363 was obviously decreased, while the expression of ins-18 was increased at the same time point (14 d). Compared with the control group, paraquat (PQ) could reduce the lifespan of the N2 and sod-5 mutant strains. Importantly, the longevity of these mutant strains recovered to normal levels when the animals were treated with exogenous hydrogen. According to these results, the lifespan of C. elegans is closely related to oxidative stress and can be significantly prolonged by reducing oxidative stress damage. Taken together, our data showed that hydrogen is a valuable antioxidant that can significantly reduce the body’s ROS levels and extend the lifespan of C. elegans. This study also laid a foundation for the subsequent application of hydrogen in antiaging studies.

Evaluation of Carotenoids Protection Against Oxidative Stress in the Animal Model Caenorhabditis elegans

The nematode Caenorhabditis elegans is a versatile and powerful model organism for animal experimental research and, despite being an invertebrate, displays remarkably similar molecular bases and conserved cellular pathways to those of humans. Oxidative stress is an etiological factor that influences numerous diseases, degenerative processes and aging. C. elegans has revealed as an opportune and feasible organism to investigate the antioxidant effects of different bioactives or complex food matrices, and a number of protocols have been developed by using different oxidative stressors. Carotenoids are recognized as quenchers and scavengers of reactive oxygen species, and many of their related health benefits attributed in the diet are tightly linked to their antioxidant properties. In this chapter, we report a simple and rapid assay to evaluate the protection capacity of pure carotenoids or complex carotenoid extracts against oxidative stress in the model system C. elegans. The protocol describes a representative feeding experiment by adding carotenoids to the nematode growth medium and after an incubation period, the C. elegans populations fed with carotenoids are exposed to an acute oxidative stress by using H₂O₂ as oxidative agent. The protection against oxidative stress is evaluated as the survival rate of the nematodes fed with the carotenoid prior to receiving oxidative treatment compared with the survival rate of control nematode population. In order to confirm the carotenoid intake by the nematodes during the feeding experiment a bioassimilation experiment is also reported.

Perfluorooctane Sulfonate (PFOS) Produces Dopaminergic Neuropathology in Caenorhabditis elegans

Perfluorooctane sulfonate (PFOS) has been widely utilized in numerous industries. Due to long environmental and biological half-lives, PFOS is a major public health concern. Although the literature suggests that PFOS may induce neurotoxicity, neurotoxic mechanisms, and neuropathology are poorly understood. Thus, the primary goal of this study was to determine if PFOS is selectively neurotoxic and potentially relevant to specific neurological diseases. Nematodes (Caenorhabditis elegans) were exposed to PFOS or related per- and polyfluoroalkyl substances (PFAS) for 72 h and tested for evidence of neuropathology through examination of cholinergic, dopaminergic, gamma-amino butyric acid (GABA)ergic, and serotoninergic neuronal morphologies. Dopaminergic and cholinergic functional analyses were assessed through 1-nonanol and Aldicarb assay. Mechanistic studies assessed total reactive oxygen species, superoxide ions, and mitochondrial content. Finally, therapeutic approaches were utilized to further examine pathogenic mechanisms. Dopaminergic neuropathology occurred at lower exposure levels (25 ppm, approximately 50 µM) than required to produce neuropathology in GABAergic, serotonergic, and cholinergic neurons (100 ppm, approximately 200 µM). Further, PFOS exposure led to dopamine-dependent functional deficits, without altering acetylcholine-dependent paralysis. Mitochondrial content was affected by PFOS at far lower exposure level than required to induce pathology (≥1 ppm, approximately 2 µM). Perfluorooctane sulfonate exposure also enhanced oxidative stress. Further, mutation in mitochondrial superoxide dismutase rendered animals more vulnerable. Neuroprotective approaches such as antioxidants, PFAS-protein dissociation, and targeted (mitochondrial) radical and electron scavenging were neuroprotective, suggesting specific mechanisms of action. In general, other tested PFAS were less neurotoxic. The primary impact is to prompt research into potential adverse outcomes related to PFAS-induced dopaminergic neurotoxicity in humans.

Tyrosine aminotransferase is involved in the oxidative stress response by metabolizing meta-tyrosine in Caenorhabditis elegans

Under oxidative stress conditions, hydroxyl radicals can oxidize the phenyl ring of phenylalanine, producing the abnormal tyrosine isomer meta-tyrosine (m-tyrosine). m-Tyrosine levels are commonly used as a biomarker of oxidative stress, and its accumulation has recently been reported to adversely affect cells, suggesting a direct role for m-tyrosine in oxidative stress effects. We found that the Caenorhabditis elegans ortholog of tyrosine aminotransferase (TATN-1)-the first enzyme involved in the metabolic degradation of tyrosine-is up-regulated in response to oxidative stress and directly activated by the oxidative stress-responsive transcription factor SKN-1. Worms deficient in tyrosine aminotransferase activity displayed increased sensitivity to multiple sources of oxidative stress. Biochemical assays revealed that m-tyrosine is a substrate for TATN-1-mediated deamination, suggesting that TATN-1 also metabolizes m-tyrosine. Consistent with a toxic effect of m-tyrosine and a protective function of TATN-1, tatn-1 mutant worms exhibited delayed development, marked reduction in fertility, and shortened lifespan when exposed to m-tyrosine. A forward genetic screen identified a mutation in the previously uncharacterized gene F01D4.5-homologous with human transcription factor 20 (TCF20) and retinoic acid-induced 1 (RAI1)-that suppresses the adverse phenotypes observed in m-tyrosine-treated tatn-1 mutant worms. RNA-Seq analysis of F01D4.5 mutant worms disclosed a significant reduction in the expression of specific isoforms of genes encoding ribosomal proteins, suggesting that alterations in protein synthesis or ribosome structure could diminish the adverse effects of m-tyrosine. Our findings uncover a critical role for tyrosine aminotransferase in the oxidative stress response via m-tyrosine metabolism.

The intestinal intermediate filament network responds to and protects against microbial insults and toxins

The enrichment of intermediate filaments in the apical cytoplasm of intestinal cells is evolutionarily conserved, forming a sheath that is anchored to apical junctions and positioned below the microvillar brush border, which suggests a protective intracellular barrier function. To test this, we used Caenorhabditis elegans, the intestinal cells of which are endowed with a particularly dense intermediate filament-rich layer that is referred to as the endotube. We found alterations in endotube structure and intermediate filament expression upon infection with nematicidal B. thuringiensis or treatment with its major pore-forming toxin crystal protein Cry5B. Endotube impairment due to defined genetic mutations of intermediate filaments and their regulators results in increased Cry5B sensitivity as evidenced by elevated larval arrest, prolonged time of larval development and reduced survival. Phenotype severity reflects the extent of endotube alterations and correlates with reduced rescue upon toxin removal. The results provide in vivo evidence for a major protective role of a properly configured intermediate filament network as an intracellular barrier in intestinal cells. This notion is further supported by increased sensitivity of endotube mutants to oxidative and osmotic stress.