Pro-oxidant and lifespan extension effects of caffeine and related methylxanthines in Caenorhabditis elegans.
ABSTRACT: Caffeine and related purine alkaloids are common ingredients of many stimulating drinks. Studies have shown that lower concentrations of caffeine have a protective role in aging-related disorders. However, the associated mode of action of caffeine and its related methylxanthines is still not clear. In this study, we demonstrated that caffeine and theophylline promote longevity in Caenorhabditis elegans. Lifespan studies with the wild type, DAF-16 and SKN-1 mutant strains indicated that the methylxanthines-mediated lifespan extension in C. elegans was independent of DAF-16/FOXO and SKN-1. All the tested methylxanthines could protect C. elegans against acute oxidative stress. At early stages of life, an increase of ROS (reactive oxygen species) induced the translocation of DAF-16 and SKN-1, resulting in upregulation of several antioxidant genes, for example, sod-3p::GFP, gst-4p::GFP, gcs-1p::GFP; and downregulation of hsp-16.2p::GFP. RT-PCR corroborates the upregulation of gst-4 and skn-1 genes. The expression of DAF-16 decreased although its nuclear translocation was induced.
Project description:Medicinal benefits of Allium vegetables, such as garlic, have been noted throughout recorded history, including protection against cancer and cardiovascular disease. We now demonstrate that garlic constituent diallyl trisulfide (DATS) increases longevity of Caenorhabditis elegans by affecting the skn-1 pathway. Treatment of worms with 5-10 ?M DATS increased worm mean lifespan even when treatment is started during young adulthood. To explore the mechanisms involved in the DATS-mediated increase in longevity, we treated daf-2, daf-16, and eat-2 mutants and found that DATS increased the lifespan of daf-2 and daf-16 mutants, but not the eat-2 mutants. Microarray experiments demonstrated that a number of genes regulated by oxidative stress and the skn-1 transcription factor were also changed by DATS treatment. Consistently, DATS treatment leads to the induction of the skn-1 target gene gst-4, and this induction was dependent on skn-1. We also found that the effects of DATS on worm lifespan depend on skn-1 activity in both in the intestine and ASI neurons. Together our data suggest that DATS is able to increase worm lifespan by enhancing the function of the pro-longevity transcription factor skn-1.
Project description:<h4>Background</h4>Caesalpinia mimosoides, a vegetable consumed in Thailand, has been reported to exhibit in vitro antioxidant properties. The in vivo antioxidant and anti-aging activities have not been investigated. The aim of this research was to study the antioxidant activity of C. mimosoides extracts in Caenorhabditis elegans, a widely used model organism in this context.<h4>Methods</h4>C. elegans were treated with C. mimosoides extracts in a various concentrations. To investigate the protective effects of the extract against oxidative stress, wild-type N2 were used to determine survival rate under oxidative stress and intracellular ROS. To study underlying mechanisms, the mutant strains with GFP reporter gene including TJ356, CF1553, EU1 and LD4 were used to study DAF-16, SOD-3, SKN-1 and GST-4 gene, respectively. Lifespan and aging pigment of the worms were also investigated.<h4>Results</h4>A leaf extract of C. mimosoides improved resistance to oxidative stress and reduced intracellular ROS accumulation in nematodes. The antioxidant effects were mediated through the DAF-16/FOXO pathway and SOD-3 expression, whereas the expression of SKN-1 and GST-4 were not altered. The extract also prolonged lifespan and decreased aging pigments, while the body length and brood size of the worms were not affected by the extract, indicating low toxicity and excluding dietary restriction.<h4>Conclusions</h4>The results of this study establish the antioxidant activity of C. mimosoides extract in vivo and suggest its potential as a dietary supplement and alternative medicine to defend against oxidative stress and aging, which should be investigated in intervention studies.
Project description:CAPE is an active constituent of propolis which is widely used in traditional medicine. This hydroxycinnamic acid derivate is a known activator of the redox-active Nrf2 signalling pathway in mammalian cells. We used C. elegans to investigate the effects of this compound on accumulation of reactive oxygen species and the modulation of the pivotal redox-active pathways SKN-1 and DAF-16 (homologues of Nrf2 and FoxO, respectively) in this model organism; these results were compared to the effects in Hct116 human colon carcinoma cells. CAPE exerts a strong antioxidative effect in C. elegans: The increase of reactive oxygen species induced by thermal stress was diminished by about 50%. CAPE caused a nuclear translocation of DAF-16, but not SKN-1. CAPE increased stress resistance of the nematode against thermal stress and finally a prolongation of the median and maximum lifespan by 9 and 17%, respectively. This increase in stress resistance and lifespan was dependent on DAF-16 as shown in experiments using a DAF-16 loss of function mutant strain. Life prolongation was retained under SKN-1 RNAi conditions showing that the effect is SKN-1 independent. The results of CAPE obtained in C. elegans differed from the results obtained in Hct116 colon carcinoma cells: CAPE also caused strong antioxidative effects in the mammalian cells, but no activation of the FoxO4 signalling pathway was detectable. Instead, an activation of the Nrf2 signalling pathway was shown by luciferase assay and western blots.CAPE activates the insulin-like DAF-16, but not the SKN-1 signalling pathway in C. elegans and therefore enhances the stress resistance and lifespan of this organism. Since modulation of the DAF-16 pathway was found to be a pivotal effect of CAPE in C. elegans, this has to be taken into account for the investigation of the molecular mechanisms of the traditional use of propolis.
Project description:The insulin/IGF signalling pathway impacts lifespan across distant taxa, by controlling the activity of nodal transcription factors. In the nematode Caenorhabditis elegans, the transcription regulators DAF-16/FOXO and SKN-1/Nrf function to promote longevity under conditions of low insulin/IGF signalling and stress. The activity and subcellular localization of both DAF-16 and SKN-1 is further modulated by specific posttranslational modifications, such as phosphorylation and ubiquitination. Here, we show that ageing elicits a marked increase of SUMO levels in C. elegans. In turn, SUMO fine-tunes DAF-16 and SKN-1 activity in specific C. elegans somatic tissues, to enhance stress resistance. SUMOylation of DAF-16 modulates mitochondrial homeostasis by interfering with mitochondrial dynamics and mitophagy. Our findings reveal that SUMO is an important determinant of lifespan, and provide novel insight, relevant to the complexity of the signalling mechanisms that influence gene expression to govern organismal survival in metazoans.
Project description:In C. elegans, the skn-1 gene encodes a transcription factor that resembles mammalian Nrf2 and activates a detoxification response. skn-1 promotes resistance to oxidative stress (Oxr) and also increases lifespan, and it has been suggested that the former causes the latter, consistent with the theory that oxidative damage causes aging. Here, we report that effects of SKN-1 on Oxr and longevity can be dissociated. We also establish that skn-1 expression can be activated by the DAF-16/FoxO transcription factor, another central regulator of growth, metabolism, and aging. Notably, skn-1 is required for Oxr but not increased lifespan resulting from over-expression of DAF-16; concomitantly, DAF-16 over-expression rescues the short lifespan of skn-1 mutants but not their hypersensitivity to oxidative stress. These results suggest that SKN-1 promotes longevity by a mechanism other than protection against oxidative damage.
Project description:The bionematicidal effect of a synthetic volatile mixture (SVM) of four volatile organic compounds (VOCs) emitted by the endophytic fungus Daldinia cf. concentrica against the devastating plant-parasitic root-knot nematode Meloidogyne javanica has been recently demonstrated in both in vitro and greenhouse experiments. However, the mode of action governing the observed irreversible paralysis of J2 larvae upon exposure to SVM is unknown. To unravel the mechanism underlying the anthelmintic and nematicidal activities, we used the tractable model worm Caenorhabditis elegans. C. elegans was also susceptible to both the fungal VOCs and SVM. Among compounds comprising SVM, 3-methyl-1-butanol, (±)-2-methyl-1-butanol, and 4-heptanone showed significant nematicidal activity toward L1, L4 and young adult stages. Egg hatching was only negatively affected by 4-heptanone. To determine the mechanism underlying this activity, we examined the response of C. elegans mutants for glutamate-gated chloride channel and acetylcholine transporter, targets of the nematicidal drugs ivermectin and aldicarb, respectively, to 4-heptanone and SVM. These aldicarb- and ivermectin-resistant mutants retained susceptibility upon exposure to 4-heptanone and SVM. Next, we used C. elegans TJ356 strain zIs356 (daf-16::GFP+rol-6), LD1 ldIs7 [skn-1B/C::GFP + pRF4(rol-6(su1006))], LD1171 ldIs3 [gcs-1p::gfp; rol-6(su1006))], CL2166 dvIs19 (gst-4p::GFP) and CF1553 muIs84 (sod-3p::GFP+rol-6), which have mutations in genes regulating multiple stress responses. Following exposure of L4 larvae to 4-heptanone or SVM, there was clear nuclear translocation of DAF-16::GFP, and SKN-1::GFP indicating that their susceptibility involves DAF-16 and SKN1 regulation. Application of 4-heptanone, but not SVM, induced increased expression of, gcs-1::GFP and gst-4::GFP compared to controls. In contrast, application of 4-heptanone or SVM to the sod-3::GFP line elicited a significant decline in overall fluorescence intensity compared to controls, indicating SOD-3 downregulation and therefore overall reduction in cellular redox machinery. Our data indicate that the mode of action of SVM and 4-heptanone from D. cf. concentrica differs from that of currently available nematicides, potentially offering new solutions for nematode management.
Project description:The transcription factor SKN-1, the C . elegans ortholog of mammalian Nrf protein, is a well-known longevity factor, and its activation is observed in several long-lived models. SKN-1 also plays essential roles in xenobiotic and oxidative stress responses. Here, we report deleterious functions of SKN-1 in somatic stress resistance that may impair lifespan. Constitutive SKN-1 activation impairs animal resistance to several stresses, including heat, ER stress and mitochondrial stress, which result from the suppression of DAF-16, another master regulator of longevity. SKN-1 activation abrogates DAF-16 nuclear import and downregulates DAF-16 target genes under stress conditions, while SKN-1 inhibition promotes the expression of DAF-16 targets, even in long-lived mutants. Further, SKN-1 activation induces the expression of vitellogenin proteins, which are required for SKN-1-mediated suppression of DAF-16 and stress resistance. Together, these findings identify detrimental roles for SKN-1 activation in animal health, and more importantly, inspire the rethinking of the complex roles for SKN-1 in aging regulation.
Project description:Dairy Propionibacterium freudenreichii is a candidate non-lactic acid probiotic. However, little information is available on the effect of P. freudenreichii on lifespan extension in humans. The aim of this study was to evaluate the effects of P. freudenreichii on lifespan extension and to elucidate the mechanism of P. freudenreichii-dependent lifespan extension in Caenorhabditis elegans. The results showed that P. freudenreichii significantly (p?<?0.05) extended the lifespan of C. elegans compared with Escherichia coli OP50, a standard food for the worm. Analysis of age-related biomarkers showed that P. freudenreichii retards ageing. Moreover, P. freudenreichii increased resistance against a human pathogen, Salmonella typhimurium, through the activation of skn-1, which is involved in pathogen resistance in C. elegans. Furthermore, P. freudenreichii-fed daf-16, jnk-1, skn-1 or daf-7 loss-of-function mutants showed an extended mean lifespan compared with E. coli OP50-fed worms. However, the increase in lifespan was not observed in pmk-1, sek-1, mek-1, dbl-1, daf-12 or daf-2 mutants, which suggests potential roles for these genes in P. freudenreichii-induced longevity in C. elegans. In conclusion, P. freudenreichii extends the lifespan of C. elegans via the p38 MAPK pathway involved in stress response and the TGF-? pathways associated with anti-inflammation processes in the immune system.
Project description:Nobiletin (NOB), one of polymethoxyflavone existing in citrus fruits, has been reported to exhibit a multitude of biological properties, including anti-inflammation, anti-oxidation, anti-atherosclerosis, neuroprotection, and anti-tumor activity. However, little is known about the anti-aging effect of NOB. The objective of this study was to determine the effects of NOB on lifespan, stress resistance, and its associated gene expression. Using Caenorhabditis elegans, an in vivo nematode model, we found that NOB remarkably extended the lifespan; slowed aging-related functional declines; and increased the resistance against various stressors, including heat shock and ultraviolet radiation. Also, NOB reduced the effects of paraquat stressor on nematodes and scavenged reactive oxygen species (ROS). Furthermore, gene expression revealed that NOB upregulated the expression of sod-3, hsp-16.2, gst-4, skn-1, sek-1, and sir-2.1, which was suggested that anti-aging activity of NOB was mediated most likely by activation of the target genes of the transcription factors including dauer formation (DAF)-16, heat-shock transcription factor (HSF)-1, and skinhead (SKN)-1. In summary, NOB has potential application in extension of lifespan, and its associated healthspan and stress resistances.
Project description:The mechanism whereby lactic acid bacteria extend the lifespan of Caenorhabditis elegans has previously been elucidated. However, the role of Weissella species has yet not been studied. We show that Weissella koreensis and Weissella cibaria significantly (p < 0.05) extend the lifespan of C. elegans compared with Escherichia coli OP50 and induce the expression of several genes related to lifespan extension (daf-16, aak-2, jnk-1, sod-3 and hif-1). Oral administration of Weissella altered reactive oxygen species (ROS) production and lowered the accumulation of lipofuscin and increased locomotor activity (which translates to a delay in ageing). Moreover, Weissella-fed C. elegans had decreased body sizes, brood sizes, ATP levels and pharyngeal pumping rates compared with E. coli OP50-fed worms. Furthermore, mutations in sod-3, hif-1 or skn-1 did not alter lifespan extension compared with wild-type C. elegans. However, C. elegans failed to display lifespan extension in loss-of-function mutants of daf-16, aak-2 and jnk-1, which highlights the potential role of these genes in Weissella-induced longevity in C. elegans. Weissella species extend C. elegans lifespan by activating DAF-16 via the c-Jun N-terminal kinase (JNK) pathway, which is related to stress response, and the AMP-activated protein kinase (AMPK)-pathway that is activated by dietary restriction.