Project description:Hydrogen sulfide (H2S) has dramatic physiological effects on animals that are associated with improved survival in changing conditions. C. elegans grown in H2S are long-lived and thermotolerant (1). To begin to identify mechanisms by which adaptation to H2S effects fundamental physiological functions, we have defined transcriptional changes associated with the response to H2S. Using microarray analysis we observe rapid changes in the abundance of specific mRNAs. The number and magnitude of transcriptional changes increased with the duration of H2S exposure. Functional annotation suggests that genes associated with protein homeostasis are upregulated upon prolonged exposure to H2S. Previous work has shown that the hypoxia-inducible transcription factor, HIF-1, is required for survival in H2S (2). We show that hif-1 is required for all early transcriptional changes in H2S. However, our data suggest that other factors may also regulate transcriptional effects of H2S exposure, and we demonstrate that SKN-1, the C. elegans homologue of NRF2, is also required for some H2S-dependent changes in transcription. Moreover, we have found that, like hif-1, skn-1 is essential to survive exposure to H2S. Our results support a model in which HIF-1 and SKN-1 coordinate a broad transcriptional response to H2S, with the end result to affect a global reorganization of protein homeostasis networks. We propose that these transcriptional responses contribute to the effects of adaptation to H2S on lifespan and thermotolerance.
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:Hypoxia-inducible transcription factor HIF is the key regulator of hypoxia response. It is conserved from human to the model organism C. elegans. The homolog of HIF in C. elegans is HIF-1. In C. elegans, there are six alternative splicing isoforms for HIF-1. Isoform a (HIF1a) is the predominant one with important biological functions for stress response and longevity. Here, by performing chromatin immunoprecipitation DNA-sequencing (ChIP-seq), we identified the direct targets for HIF-1a at whole genome level.
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:Physiological memories of environmental stress can serve to predict future environmental changes, allowing the organism to initiate protective mechanisms and survive. Although physiological memories, or bookmarks, of environmental stress have been described in a wide range of organisms, from bacteria to plants to humans, the mechanism by which these memories persist in the absence of stress is still largely unknown. We have discovered that C. elegans transiently exposed to low doses of hydrogen sulfide (H2S) survive subsequent exposure to otherwise lethal H2S concentrations and induce H2S-responsive transcripts more robustly than naïve controls. H2S bookmarking can occur at any developmental stage and persists through cell divisions and development but is erased by fasting. We show that maintenance of the H2S bookmark requires the SET-2 histone methyltransferase and the CoREST-like demethylase complex. We propose a model in which exposure to low doses of H2S generates a long-lasting, epigenetic memory by modulating H3K4me2 modifications at specific promoters. Understanding the fundamental aspects of H2S bookmarking in this tractable system can provide mechanistic insight into how environmental exposures are translated into the epigenetic landscape in animals.