Tiller, George R. et al. (2013) International Worm Meeting "Potential Roles of Peroxidases in C. elegans Innate Immunity."

Garsin, Danielle A., Tiller, George R.

[International Worm Meeting, 2013]

ROS (reactive oxygen species) are produced at mucosal epithelial surfaces, as part of the innate immune response to combat invading pathogens. The proteins responsible for this ROS production belong to the NOX/DUOX (NADPH Oxidase and Dual Oxidase) family and include C. elegans Ce-Duox1/BLI-3. It was previously shown that in response to infection with Enterococcus faecalis, BLI-3 released ROS, and reduction of bli-3 expression caused the worms to be significantly more susceptible. Additionally, DUOXs are known to generate ROS for use by peroxidases, which then generate more potent oxidation products that aid in the host's innate immune response. An example is human lactoperoxidase (hLPO), which uses ROS from hDUOX2 to produce hypothiocyanite to facilitate clearance in the airway epithelia. Based on this information, we hypothesized that BLI-3-generated ROS may act as a substrate for peroxidases to generate antimicrobial agents in the C. elegans immune response. Using bli-3 as the query, WormBase.org was searched for homologous genes. The genes-of-interest were screened for a susceptibility-to-pathogen phenotype in C. elegans using RNAi (RNA interference) to reduce their expression. Genes necessary for full resistance against pathogen were further tested for general fitness defects using longevity assays. F49E12.1 RNAi worms incubated with E. faecalis at 25 deg C displayed an increased susceptibility phenotype (P-value = 0.0011; median survival: 189 and 165 hours, V.C. and F49E12.1, respectively). As determined by Amplex Red, when infected, F49E12.1 RNAi worms display increased H2O2 levels relative to vector control (P-value = 0.0068) which suggests F49E12.1 utilizes H2O2 for a, currently, unknown purpose. Interestingly, F49E12.1 possesses significant homology to peroxidases that are crucial for innate immunity in crustaceans as well as mammals. Therefore, the current focus is to elucidate how the putative peroxidase F49E12.1 contributes to the C. elegans innate immune response.

McCallum, Katie et al. (2013) International Worm Meeting "A redox sensor as a potential regulator of ROS signaling in C. elegans."

Garsin, Danielle, McCallum, Katie, Miranda-Vizuete, Antonio

[International Worm Meeting, 2013]

The ability of an organism to maintain redox homeostasis is critical for its survival. At the cellular level, exposure to oxidative insult can irreversibly damage DNA, proteins, and lipids, all of which can lead to cell apoptosis or necrosis. To counteract such oxidative insults, organisms have developed the ability to sense and respond to oxidative stress, termed the oxidative stress response. SKN-1 is the major transcription factor that coordinates the C. elegans oxidative stress response. Our lab has recently demonstrated that, in C. elegans, intestinal infections stimulate the production of reactive oxygen species (ROS) by Ce-Duox1/BLI-3. While this response has protective effects, it challenges the host's intracellular redox homeostasis, resulting in the simultaneous up-regulation of intracellular detoxification enzymes. This response occurs through the activation of SKN-1, in a p38 MAPK pathway dependent manner. However, it is still currently unknown how BLI-3-generated ROS is capable of activating SKN-1. This question is of broad interest because ROS can serve as an important signaling molecule not only in the immune response, but in the regulation of other vital processes such as cell growth and differentiation. We propose that activation of the SKN-1 is regulated by a redox sensor, which is sensitive to the ROS generated by BLI-3.

Bolm M et al. (2004) Science "Bacterial resistance in daf-2 mutants."

Jansen WTM, Chhatwal GS, Bolm M

[Science, 2004]

In their Brevia "Long-lived C. elegans daf-2 mutants are resistant to bacterial pathogens," D.A. Garsin et al. show that long-lived C. elegans daf-2 mutants are resistant to killing by bacterial pathogens. Partial loss-of-function mutations in daf-2, which encodes an insulin-like receptor, results in de-repression of the transcription factor daf-16, leading to life extension and increased resistance to bacterial pathogens Enterococcus faecalis, Staphylococcus aureus, and Pseudomonas aeruginosa.

McCallum, Katie et al. (2015) International Worm Meeting "TRX-1 as a potential redox regulator of the major C. elegans oxidative stress transcription factor, SKN-1."

Miranda-Vizuete, Antonio, McCallum, Katie, Liu, Bin, Arur, Swathi, Garsin, Danielle, Swoboda, Peter, Fierro-Gonzalez, Juan Carlos

[International Worm Meeting, 2015]

The ability of an organism to maintain oxidative homeostasis is critical for its survival. At the cellular level, exposure to oxidative insult can irreversibly damage DNA, proteins, and lipids, all of which can lead to cell apoptosis or necrosis. At the organismal level, unresolved oxidative stress can lead to several life-threatening diseases, including Alzheimer's, Parkinson's disease, and atherosclerosis. Our lab uses the model organism C. elegans to study the regulation of the major oxidative stress transcription factor, SKN-1, which is a functional homolog of the major mammalian oxidative stress transcription factor, Nrf2. Recently, we identified a thioredoxin as a novel regulator of SKN-1. Thioredoxins are small redox reactive proteins that have been shown to play a prominent role in redox signaling. In light of this, we hypothesized that thioredoxins are the 'first responders' to oxidative stress and may serve as the link between stress sensing and stress signaling that has yet to be fully elucidated in many organisms. In support of this hypothesis, we have shown that the loss of trx-1 promotes intestinal nuclear localization of SKN-1, even in the absence of stress, indicating that TRX-1 regulates SKN-1 localization. Interestingly, TRX-1-dependent regulation of intestinal SKN-1 nuclear localization is specific, occurs cell non-autonomously, and is dependent on the p38 MAPK pathway. However, while TRX-1 is able to regulate SKN-1 localization, we do not see increased activation of this transcription factor. Interestingly, loss of trx-1 elicited a general, organismal down-regulation of several classes of genes, with collagens and lipid transport and localization proteins being most prevalent. However, one prominent lipase-related gene, lips-6, was highly up regulated upon loss of trx-1. Furthermore, this up regulation was dependent on skn-1.

Eric A Evans et al. (2004) West Coast Worm Meeting "The daf-2 insulin signaling pathway independently regulates ageing and immunity"

Man-Wah Tan, Eric A Evans

[West Coast Worm Meeting, 2004]

The C. elegans daf-2 insulin signaling pathway has been implicated in resistance to bacterial pathogens. Garsin et al. (2003) demonstrated that daf-2 and age-1 worms are resistant to a variety of bacterial pathogens {Science 300: 1921}. However, it has been suggested that the appearance of resistance is merely mediated by anti-ageing enhancements of daf-2 animals {Bolm et al., 2004, Science 303: 1976}. Here we report that increased daf-2 lifespan on pathogenic bacteria is associated with restricted bacterial colonization of the worm intestine. We show that germ line signaling also regulates a DAF-16 dependent resistance to bacterial pathogens. We also demonstrate that the immune function of daf-2 signaling is mediated by signaling through AKT-1 and AKT-2, but not PDK-1 and SGK-1. The converse has been reported for ageing {Hertweck et al., 2004, Dev Cell 6: 577-588}. Thus, ageing and immunity are controlled by distinct components of the daf-2 signaling pathway.

Dasgupta, Madhumanti et al. (2020) MicroPubl Biol

Singh, Varsha, Shashikanth, Meghana, Dasgupta, Madhumanti, Bojanala, Nagagireesh

[MicroPubl Biol, 2020]

Caenorhabditis elegans feeds on bacteria in decomposing vegetation. Lipids, carbohydrates and proteins derived from microbes are digested into fatty acids, simple sugars and amino acids in C. elegans alimentary canal and absorbed by intestinal cells containing microvilli. Approximately 80% of fatty acids in C. elegans is derived from E. coli (Perez and Van Gilst, 2008). Nutrient limiting conditions can cause developmental delay in larvae (Cassada and Russell, 1975; Golden and Riddle, 1982) while complete starvation leads to L1 larval arrest or dauer formation (Baugh, 2013). Interestingly it has been reported that C. elegans fed on yeast Cryptococcus curvatus show developmental lag (Sanghvi et al., 2016) and growth arrest on Gram-positive bacterium Enterococcus faecalis (Garsin et al., 2001). We have recently shown that E. faecalis infection causes lipid droplet utilization in adult C. elegans, a process termed immunometabolism (Dasgupta et al., 2020). In this study, we have investigated the developmental arrest induced by E. faecalis in C. elegans larvae to show that the arrest is induced at L1 and L2 larva stage.

KA Swan et al. (1999) International C. elegans Meeting "or191ts and or182ts are Embryonic Lethal, Temperature-Sensitive Mutations that Disrupt Spindle Rotation and Cell Cycle Timing, Respectively, in Two-Cell Stage C. elegans Embryos."

DR Hamill, BA Bowerman, KA Swan

[International C. elegans Meeting, 1999]

In order to understand the processes governing the establishment of asymmetry within the early C. elegans embryo, our lab has begun an investigation of several conditional mutants isolated in a screen for temperature sensetive, embryonic lethal mutations (see abstract by D. Hamill). Two of these mutations, or191ts and or182ts disrupt different aspects of asymmetry normally observed at the two-cell stage. The or191ts mutation results in random spindle orientation within the two-cell stage blastomeres AB and P 1 , which normally divide transversely and longitudinally, respectively. In addition to dividing along different axes, the cell cycle times of AB and P 1 are unequal in wild-type embryos, with AB dividing slightly ahead of P 1 . A second mutation we have identified increases this asymmetry. The mutation or182ts , delays the cell cycle timing of both AB and P 1 . The AB cell cycle time, however, is increased only slightly, while the time of the P 1 cell cycle is doubled. or191ts maps to the center of chromosome V while or182ts maps to the far left arm of chomosome III. Phenotypic analysis of these mutants and progress on identifying the affected genes will be presented. For information concerning the analysis of other mutants affecting similar processes see posters presented by Danielle Hamill and Sandra Encalada in our laboratory.

Martin, Jack et al. (2021) International Worm Meeting "The kynurenine pathway is a major modulator of E. faecalis infection in C. elegans"

Whittingham-Dowd, Jayde, Cetnar, Kalina, Rezwana, Ruhi, Norvaisas, Povilas, Kosztelnik, Monika, Parry, Jackie, Au, Catherine, Martin, Jack, Cabreiro, Filipe, Zarate Potes, Alejandra, Urbaniak, Mick, Gems, David, Fathallah, Nadin, Hardgrave, Alex, Benedetto, Alexandre

[International Worm Meeting, 2021]

Key words Kynurenine pathway, E. faecalis, gut infection, microbiota, lysosome-related organelles autofluorescence. Abstract The kynurenine pathway (KP), main catabolic route for the essential amino-acid tryptophan, is well-known for its immunomodulatory role in mammals. While investigating death fluorescence in C. elegans, anthranilic acid (AA)-loaded lysosome-related organelles (LROs) were previously found responsible for the blue auto-fluorescence seen in the worm gut (Coburn et al. PLOS Biol. 2013). Given the bacteriostatic potential of AA and other kynurenine pathway compounds, we hypothesised that LROs and the KP play a key role in C. elegans gut microbial control. To test this idea, we exposed C. elegans to a worm-pathogenic strain of E. faecalis (OG1RF) and observed changes in gut morphology and autofluorescence dynamics upon infection. Transcriptomics and targeted metabolomics analyses further showed that KP activity is modulated upon E. faecalis infection. Using a combination of KP mutants from the Nollen lab (Van Der Goot et al. PNAS 2012), we observed that inhibition of various KP enzymes differentially affect C. elegans resistance to E. faecalis infection. E. faecalis growth on KP mutant worm extracts confirmed that resistant mutants produce bacteriostatic compounds, which we measured by HPLC. This was verified by the delayed or reduced gut colonisation of OG1RF-GFP (gifted by D. Garsin), and the ability for some mutants to thrive on OG1RF loans. We are currently investigating a broader role for the KP in C. elegans gut microbiota control, notably using newly generated CeMBio fluorescent strains.

Consortium Wormbase (2000) Worm Breeder's Gazette "Update on the C. elegans database WormBase"

Consortium Wormbase

[Worm Breeder's Gazette, 2000]

WormBase (www.wormbase.org) is an international consortium of biologists and computer scientists dedicated to providing the research community with accurate, current, accessible information concerning the genetics, genomics and biology of C. elegans and some related nematodes. WormBase builds upon the existing ACeDB database of the C. elegans genome by providing curation from the literature, an expanded range of content and a user friendly web interface. The team that developed and maintained ACeDB (Richard Durbin, Jean Thierry-Mieg) remains an important part of WormBase. Lincoln Stein and colleagues at Cold Spring Harbor are leading the effort to develop the user interface, including visualization tools for the genome and genetic map. Teams at Sanger Centre (led by Richard Durbin) and the Genome Sequencing Center at Washington University, St. Louis (led by John Spieth) continue to curate the genomic sequence. Jean and Danielle Thierry-Mieg at NCBI spearhead importation of large-scale data sets from other projects. Paul Sternberg and colleagues at Caltech will curate new data including cell function in development, behavior and physiology, gene expression at a cellular level; and gene interactions. Paul Sternberg assumes overall responsibility for WormBase, and is delighted to hear feedback of any sort. WormBase has recently received major funding from the National Human Genome Research Institute at the US National Institutes of Health, and also receives support from the National Library of Medicine/NCBI and the British Medical Research Council. WormBase is an expansion of existing efforts, and as such continues to need you help and feedback. Even with the increased scope and funding, all past contributors to ACeDB remain involved. The Caenorhabditis Genetics Center (Jonathan Hodgkin and Sylvia Martinelli) collaborate with WormBase to curate the genetic map and related topics. Ian Hope and colleagues continue to supply expression data to WormBase. Leon Avery will continue his superb website and serves as one advisor to WormBase. While the major means of access to WormBase is via the world wide web, downloadable versions of WormBase as well as the acedb software engine will continue to be available.

Eric A Evans et al. (2005) International Worm Meeting "The regulation of innate immunity by the DAF-2 insulin signaling pathway: CBP-1 is a potential DAF-16 cofactor"

Eric A Evans, Man-Wah Tan

[International Worm Meeting, 2005]

The insulin/IGF-1 (DAF-2) signaling pathway regulates innate immunity in C. elegans. We and others have previously shown that mutations in daf-2 pathway genes and glp mutants enhance resistance to bacterial pathogens in a manner dependent on the FoxO transcription factor DAF-16 (1).Acetylation by CBP/p300, transcriptional cofactors with histone acetyltransferase activity, has been implicated as a regulator of FoxO activity in mammalian systems (2-5). These studies have suggested a model in which binding of CBP/p300 to FoxO factors is essential for FoxO-mediated transcription (6). Corroborating this model, we will present evidence that cbp-1, the worm CPB/p300 homolog, is essential for the immunity enhancements mediated by DAF-16. RNAi of cbp-1 at L4 suppresses resistance to Pseudomonas aeruginosa in the rrf-3(pk1426);glp-4(bn2) double mutant strain to the same extent as daf-16 RNAi does.We also observe that continuous exposure of daf-2(e1370) mutant worms to the cbp-1 RNAi feeding strain results in early death at a rate similar to daf-16 RNAi. Assigning significance to this suppression with regard to the distinction between aging and immunity is not straightforward because live bacteria are used to induce RNAi. Although E. coli is often regarded as a non-pathogenic food for worms, there is evidence that bacterial proliferation is a cause of death in aging worms (7). We believe the confounding of aging and immunity within these assays is a problem that warrants further investigation.We are investigating the relationship between aging and immunity in the context of the DAF-2 pathway. We will present evidence for a model of distinct regulation of aging and immunity.(1) Garsin (2003) Science 300. (2) Brunet (2004) Science 303. (3) Motta (2004) Cell 116. (4) Daitoku (2004) PNAS 101. (5) van der Horst (2004) JBC 279. (6) van der Heide (2005) Trends Biochem Sci. 30. (7) Garigan (2002) Genetics 161.