Project description:Oxidative stress may play a role in normal aging. SKN-1 is a transcription factor necessary for intestine development in Caenorhabditis elegans, which also regulates the response to oxidative stress post-embryonically. Using DNA microarrays, we found that oxidative stress induces the antioxidant response, the heat shock response, and detoxification genes, while the expression of genes involved in homeostasis, development, and reproduction were decreased. Both up-regulated and down-regulated genes can be wholly, partially, or not at all dependent on SKN-1 action. However, induction of the heat shock response by oxidative stress was not affected by SKN-1 removal. Keywords: stress response
Project description:The Caenorhabditis elegans oxidative stress response transcription factor, SKN-1, is essential for the maintenance of redox homeostasis and is a functional ortholog of the Nrf family of transcription factors. The numerous levels of regulation that govern these transcription factors underscore their importance. Here, we add a thioredoxin, encoded by trx-1, to the expansive list of SKN-1 regulators. We report that loss of trx-1 promotes nuclear localization of intestinal SKN-1 in a redox-independent, cell non-autonomous fashion from the ASJ neurons. Furthermore, this regulation is not general to the thioredoxin family, as two other C. elegans thioredoxins TRX-2 and TRX-3 do not play a role in this process. Moreover, TRX-1-dependent regulation requires signaling from the p38 MAPK signaling pathway. However, while TRX-1 regulates SKN-1 nuclear localization, SKN-1 transcriptional activity remains largely unaffected. Interestingly, RNA-Seq revealed that loss of trx-1 elicits a general, organism-wide down-regulation of several classes of genes; those encoding for collagens and lipid transport and localization being most prevalent. However, one prominent lipase-related gene, lips-6, is highly up regulated upon loss of trx-1 in a skn-1-dependent manner. Together, these results uncover a novel role for a thioredoxin in regulating intestinal SKN-1 nuclear localization in a cell non-autonomous manner, thereby contributing to the understanding of the processes involved in maintaining redox homeostasis throughout an organism. Four samples were analyzed: Two nematode strains were analyzed, each under non-stressed and stressed (10mM NaAs) conditions
Project description:The Caenorhabditis elegans oxidative stress response transcription factor, SKN-1, is essential for the maintenance of redox homeostasis and is a functional ortholog of the Nrf family of transcription factors. The numerous levels of regulation that govern these transcription factors underscore their importance. Here, we add a thioredoxin, encoded by trx-1, to the expansive list of SKN-1 regulators. We report that loss of trx-1 promotes nuclear localization of intestinal SKN-1 in a redox-independent, cell non-autonomous fashion from the ASJ neurons. Furthermore, this regulation is not general to the thioredoxin family, as two other C. elegans thioredoxins TRX-2 and TRX-3 do not play a role in this process. Moreover, TRX-1-dependent regulation requires signaling from the p38 MAPK signaling pathway. However, while TRX-1 regulates SKN-1 nuclear localization, SKN-1 transcriptional activity remains largely unaffected. Interestingly, RNA-Seq revealed that loss of trx-1 elicits a general, organism-wide down-regulation of several classes of genes; those encoding for collagens and lipid transport and localization being most prevalent. However, one prominent lipase-related gene, lips-6, is highly up regulated upon loss of trx-1 in a skn-1-dependent manner. Together, these results uncover a novel role for a thioredoxin in regulating intestinal SKN-1 nuclear localization in a cell non-autonomous manner, thereby contributing to the understanding of the processes involved in maintaining redox homeostasis throughout an organism.
Project description:Reactive Oxygen Species increase gradually with aging and Steadily diminish the cell's ability to maintain homeostasis. Nuclear Factor-like 2 and its C elegans ortholog, SKN-1 are transcription factors that play a pivotal role in oxidative stress response, cellular homeostasis and lifespan. But like other defence systems, Nrf2-mediated stress response is compromised in aging and neurodegenerative diseases. In this study we provide evidence that this FDA-approved drug is a bona fide activator of Nrf2/SKN-1 pathway.
Project description:Hormesis occurs when a low level stress elicits adaptive beneficial responses that protect against subsequent exposure to severe stress. Recent findings suggest that mild oxidative and thermal stress can extend lifespan by hormetic mechanisms. Here we show that the botanical pesticide plumbagin, while toxic to C. elegans nematodes at high doses, extends lifespan at low doses. Because plumbagin is a naphthoquinone that generates free radicals in vivo, we investigated whether it extends lifespan by activating an adaptive cellular stress response pathway. Mammalian NF-E2-related factor 2 (Nrf2) and its C. elegans ortholog SKN-1, mediate protective responses to oxidative stress by promoting target gene expression via antioxidant response elements (ARE). Genetic analyses showed that skn-1 mediates plumbagin’s lifespan-extending effect in C. elegans. Further screening of a series of plumbagin analogs identified three additional naphthoquinones that could induce SKN-1 targets in C. elegans. Naphthazarin showed skn-1-dependent lifespan extension, over an extended dose range compared to plumbagin, while the other naphthoquinones, oxoline and menadione, had differing effects on C. elegans survival and failed to activate ARE reporter expression in cultured mammalian cells. Our findings reveal the potential for low doses of naturally occurring naphthoquinones to extend lifespan by engaging a specific adaptive cellular stress response pathway.
Project description:The role of ellagic acid (EA), a natural antioxidant, in regulating anti-aging and its underlying mechanisms remains unclear. In this study, we investigated the anti-aging effects and molecular mechanisms of EA in Caenorhabditis elegans (C. elegans). Our results demonstrate that EA extends the lifespan of C. elegans, enhances motility, reduces lipofuscin accumulation, and improves overall healthspan. Additionally, EA reduces reactive oxygen species (ROS) accumulation in C. elegans under conditions of heat and oxidative stress. The insulin/IGF-1 signaling (IIS) pathway, a key regulator of longevity and stress resistance in C. elegans, was found to mediate EA's effects. EA treatment did not extend the lifespan of mutants defective in daf-2, daf-16, hsf-1, hlh-30, and skn-1, confirming that EA’s lifespan-extending effect operates through the IIS pathway. Furthermore, EA treatment increased the expression of stress response genes downstream of the IIS pathway. Based on RNA sequencing data, we further explored the molecular mechanisms and potential regulatory roles of EA in anti-aging.
Project description:Mitis group streptococci are opportunistic pathogens residing in the oral cavity, where they produce hydrogen peroxide (H2O2), a key virulence factor contributing to their pathogenesis. We previously demonstrated that these bacteria kill the nematode Caenorhabditis elegans through H2O2 production. Metformin, a widely used biguanide drug for managing blood glucose levels, has shown promising effects on aging by extending lifespan in worms and mice, and has also demonstrated potential cancer treatment. Additionally, pretreatment with metformin enhances the survival of worms and triggers an immune response via the p38 MAPK pathway against various pathogenic bacteria. Based on these observations, we investigated metformin's potential as a therapeutic agent against mitis group streptococcal infections and its underlying mechanisms in the current study. Pretreatment of worms with metformin provided significant dose-dependent protection from streptococcal-derived H2O2. This protective effect was attributed to the activation of the oxidative stress response transcription factor SKN-1/NRF2. Further analysis revealed that the p38 MAPK pathway and the transcription mediator complex protein MDT-15 are essential for the activation of SKN-1 by metformin. Interestingly, SKN-1 activity, mediated by MDT-15, was found to be independent of the p38 MAPK pathway. Our findings establish that metformin-mediated protection against mitis group streptococcal infections relies on the coordinated action of SKN-1, the p38 MAPK pathway, and MDT-15. These insights suggest that metformin could be a valuable therapeutic agent in combating these infections. Future research should focus on further elucidating the molecular mechanisms involved and exploring the potential clinical applications of metformin in treating these bacterial infections.
Project description:Pimozide is a potent inhibitor of dopamine-like D2-like receptors (D2R) and has been approved by the FDA and widely used in clinical treatment. Although various monoamine antipsychotic drugs have shown potential as anti-aging agents, the role of pimozide in aging remains unclear. We found that pimozide can extend the lifespan of C. elegans, as well as its healthy lifespan, manifested by increased activity, reduced accumulation of lipofuscin, and enhanced stress resistance. RNA-seq results showed that pimozide significantly upregulated the expression of collagen genes and induced an increase in collagen protein synthesis. Moreover, pimozide extends the lifespan of nematodes through the skn-1 pathway, while in skn-1(EU-1), the lifespan-extending effect of pimozide is eliminated. In summary, these findings indicate that pimozide can promote the health and lifespan of C. elegans through the skn-1-collagen pathway.
Project description:Oxidative stress may play a role in normal aging. SKN-1 is a transcription factor necessary for intestine development in Caenorhabditis elegans, which also regulates the response to oxidative stress post-embryonically. Using DNA microarrays, we found that oxidative stress induces the antioxidant response, the heat shock response, and detoxification genes, while the expression of genes involved in homeostasis, development, and reproduction were decreased. Both up-regulated and down-regulated genes can be wholly, partially, or not at all dependent on SKN-1 action. However, induction of the heat shock response by oxidative stress was not affected by SKN-1 removal. Experiment Overall Design: TJ1060 was grown at 16 ï°C. Eggs were collected by hypochlorite, hatched overnight at 20 ï°C (Emmons, 1979 #52) and first-stage larvae (L1âs) were placed onto 2 % peptone plates (1.7 % agar, 20 g/l peptone, 25 mM NaCl, 50 mM KH2PO4 pH 6.0, 5 µg/ml cholesterol, 1 mM CaCl2, 1 mM MgSO4) at 25 ï°C. Sterile 3 day old young adult animals on peptone plates were treated with 99 % O2 at 40 PSI for 6 hours at 20 ï°C in a hyperbaric O2 chamber. Half of the worms were untreated and served as a control population. A small plate of strain CL2166 [dvIs19 pAF15(gst-4::GFP::NLS)] was used as an indicator strain and checked for GFP induction in both control and experimental conditions. Worms were harvested by washing off plates with S-basal and quick frozen in liquid nitrogen. Total RNA was prepared using TRIZOL reagent and standard protocols and cleaned up on Qiagen RNeasy columns. The Affymetrix labeling kit was used to prepare labeled cRNA as a target for the Affymetrix GeneChip® C.elegans Genome Array. Gene chip hybridization and scanning were done at Genome Explorations (Memphis, MN) and the University of Colorado at Boulder Gene Chip Core Facility (Boulder, CO).